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Gu, Peng, Li, Shuangchen, Stow, Dylan, Barnes, Russell, Liu, Liu, Xie, Yuan, Kursun, Eren.  2016.  Leveraging 3D Technologies for Hardware Security: Opportunities and Challenges. Proceedings of the 26th Edition on Great Lakes Symposium on VLSI. :347–352.

3D die stacking and 2.5D interposer design are promising technologies to improve integration density, performance and cost. Current approaches face serious issues in dealing with emerging security challenges such as side channel attacks, hardware trojans, secure IC manufacturing and IP piracy. By utilizing intrinsic characteristics of 2.5D and 3D technologies, we propose novel opportunities in designing secure systems. We present: (i) a 3D architecture for shielding side-channel information; (ii) split fabrication using active interposers; (iii) circuit camouflage on monolithic 3D IC, and (iv) 3D IC-based security processing-in-memory (PIM). Advantages and challenges of these designs are discussed, showing that the new designs can improve existing countermeasures against security threats and further provide new security features.

Alasad, Qutaiba, Yuan, Jiann, Fan, Deliang.  2017.  Leveraging All-Spin Logic to Improve Hardware Security. Proceedings of the on Great Lakes Symposium on VLSI 2017. :491–494.

Due to the globalization of Integrated Circuit (IC) design in the semiconductor industry and the outsourcing of chip manufacturing, third Party Intellectual Properties (3PIPs) become vulnerable to IP piracy, reverse engineering, counterfeit IC, and hardware trojans. A designer has to employ a strong technique to thwart such attacks, e.g. using Strong Logic Locking method [1]. But, such technique cannot be used to protect some circuits since the inserted key-gates rely on the topology of the circuit. Also, it requires higher power, delay, and area overheads compared to other techniques. In this paper, we present the use of spintronic devices to help protect ICs with less performance overhead. We then evaluate the proposed design based on security metric and performance overhead. One of the best spintronic device candidates is the All Spin Logic due to its unique properties: small area, no spin-charge signal conversion, and its compatibility with conventional CMOS technology.

Hosseini, Fateme S., Fotouhi, Pouya, Yang, Chengmo, Gao, Guang R..  2017.  Leveraging Compiler Optimizations to Reduce Runtime Fault Recovery Overhead. Proceedings of the 54th Annual Design Automation Conference 2017. :20:1–20:6.

Smaller feature size, lower supply voltage, and faster clock rates have made modern computer systems more susceptible to faults. Although previous fault tolerance techniques usually target a relatively low fault rate and consider error recovery less critical, with the advent of higher fault rates, recovery overhead is no longer negligible. In this paper, we propose a scheme that leverages and revises a set of compiler optimizations to design, for each application hotspot, a smart recovery plan that identifies the minimal set of instructions to be re-executed in different fault scenarios. Such fault scenario and recovery plan information is efficiently delivered to the processor for runtime fault recovery. The proposed optimizations are implemented in LLVM and GEM5. The results show that the proposed scheme can significantly reduce runtime recovery overhead by 72%.

Ardi, Calvin, Heidemann, John.  2018.  Leveraging Controlled Information Sharing for Botnet Activity Detection. Proceedings of the 2018 Workshop on Traffic Measurements for Cybersecurity. :14-20.

Today's malware often relies on DNS to enable communication with command-and-control (C&C). As defenses that block C&C traffic improve, malware use sophisticated techniques to hide this traffic, including "fast flux" names and Domain-Generation Algorithms (DGAs). Detecting this kind of activity requires analysis of DNS queries in network traffic, yet these signals are sparse. As bot countermeasures grow in sophistication, detecting these signals increasingly requires the synthesis of information from multiple sites. Yet sharing security information across organizational boundaries to date has been infrequent and ad hoc because of unknown risks and uncertain benefits. In this paper, we take steps towards formalizing cross-site information sharing and quantifying the benefits of data sharing. We use a case study on DGA-based botnet detection to evaluate how sharing cybersecurity data can improve detection sensitivity and allow the discovery of malicious activity with greater precision.

Moyer, T., Chadha, K., Cunningham, R., Schear, N., Smith, W., Bates, A., Butler, K., Capobianco, F., Jaeger, T., Cable, P..  2016.  Leveraging Data Provenance to Enhance Cyber Resilience. 2016 IEEE Cybersecurity Development (SecDev). :107–114.

Building secure systems used to mean ensuring a secure perimeter, but that is no longer the case. Today's systems are ill-equipped to deal with attackers that are able to pierce perimeter defenses. Data provenance is a critical technology in building resilient systems that will allow systems to recover from attackers that manage to overcome the "hard-shell" defenses. In this paper, we provide background information on data provenance, details on provenance collection, analysis, and storage techniques and challenges. Data provenance is situated to address the challenging problem of allowing a system to "fight-through" an attack, and we help to identify necessary work to ensure that future systems are resilient.

Haider, Syed Kamran, Omar, Hamza, Lebedev, Ilia, Devadas, Srinivas, van Dijk, Marten.  2017.  Leveraging Hardware Isolation for Process Level Access Control & Authentication. Proceedings of the 22Nd ACM on Symposium on Access Control Models and Technologies. :133–141.

Critical resource sharing among multiple entities in a processing system is inevitable, which in turn calls for the presence of appropriate authentication and access control mechanisms. Generally speaking, these mechanisms are implemented via trusted software "policy checkers" that enforce certain high level application-specific "rules" to enforce a policy. Whether implemented as operating system modules or embedded inside the application ad hoc, these policy checkers expose additional attack surface in addition to the application logic. In order to protect application software from an adversary, modern secure processing platforms, such as Intel's Software Guard Extensions (SGX), employ principled hardware isolation to offer secure software containers or enclaves to execute trusted sensitive code with some integrity and privacy guarantees against a privileged software adversary. We extend this model further and propose using these hardware isolation mechanisms to shield the authentication and access control logic essential to policy checker software. While relying on the fundamental features of modern secure processors, our framework introduces productive software design guidelines which enable a guarded environment to execute sensitive policy checking code - hence enforcing application control flow integrity - and afford flexibility to the application designer to construct appropriate high-level policies to customize policy checker software.

Feyisetan, Oluwaseyi, Diethe, Tom, Drake, Thomas.  2019.  Leveraging Hierarchical Representations for Preserving Privacy and Utility in Text. 2019 IEEE International Conference on Data Mining (ICDM). :210—219.

Guaranteeing a certain level of user privacy in an arbitrary piece of text is a challenging issue. However, with this challenge comes the potential of unlocking access to vast data stores for training machine learning models and supporting data driven decisions. We address this problem through the lens of dx-privacy, a generalization of Differential Privacy to non Hamming distance metrics. In this work, we explore word representations in Hyperbolic space as a means of preserving privacy in text. We provide a proof satisfying dx-privacy, then we define a probability distribution in Hyperbolic space and describe a way to sample from it in high dimensions. Privacy is provided by perturbing vector representations of words in high dimensional Hyperbolic space to obtain a semantic generalization. We conduct a series of experiments to demonstrate the tradeoff between privacy and utility. Our privacy experiments illustrate protections against an authorship attribution algorithm while our utility experiments highlight the minimal impact of our perturbations on several downstream machine learning models. Compared to the Euclidean baseline, we observe \textbackslashtextgreater 20x greater guarantees on expected privacy against comparable worst case statistics.

Jenkins, J., Cai, H..  2018.  Leveraging Historical Versions of Android Apps for Efficient and Precise Taint Analysis. 2018 IEEE/ACM 15th International Conference on Mining Software Repositories (MSR). :265-269.

Today, computing on various Android devices is pervasive. However, growing security vulnerabilities and attacks in the Android ecosystem constitute various threats through user apps. Taint analysis is a common technique for defending against these threats, yet it suffers from challenges in attaining practical simultaneous scalability and effectiveness. This paper presents a novel approach to fast and precise taint checking, called incremental taint analysis, by exploiting the evolving nature of Android apps. The analysis narrows down the search space of taint checking from an entire app, as conventionally addressed, to the parts of the program that are different from its previous versions. This technique improves the overall efficiency of checking multiple versions of the app as it evolves. We have implemented the techniques as a tool prototype, EVOTAINT, and evaluated our analysis by applying it to real-world evolving Android apps. Our preliminary results show that the incremental approach largely reduced the cost of taint analysis, by 78.6% on average, yet without sacrificing the analysis effectiveness, relative to a representative precise taint analysis as the baseline.

Amin, Syed Obaid, Zheng, Qingji, Ravindran, Ravishankar, Wang, GQ.  2016.  Leveraging ICN for Secure Content Distribution in IP Networks. Proceedings of the 2016 ACM on Multimedia Conference. :765–767.

Recent studies shows that by the end of 2016 more than 60% of Internet traffic would be running on HTTPS. In presence of secure tunnels such as HTTPS, transparent caching solutions become in vain, as the application payload is encrypted by lower level security protocols. This paper addresses this issue and provides an alternate approach, for contents caching without compromising their security. There are three parts to our proposal. First, we propose two new IP layer primitives that allow routers to differentiate between IP and ICN flows. Second, we introduce DCAR (Dual-mode Content Aware Router), which is a traditional IP router enabled to understand the proposed IP primitives. Third, design of DISCS (DCAR based Information centric Secure Content Sharing) framework is proposed that leverages DCAR to allow content object caching along with security services that are comparable to HTTPS. Finally we share details on realizing such system.

Bollig, Evan F., Allan, Graham T., Lynch, Benjamin J., Huerta, Yectli A., Mix, Mathew, Munsell, Edward A., Benson, Raychel M., Swartz, Brent.  2018.  Leveraging OpenStack and Ceph for a Controlled-Access Data Cloud. Proceedings of the Practice and Experience on Advanced Research Computing. :18:1-18:7.

While traditional HPC has and continues to satisfy most workflows, a new generation of researchers has emerged looking for sophisticated, scalable, on-demand, and self-service control of compute infrastructure in a cloud-like environment. Many also seek safe harbors to operate on or store sensitive and/or controlled-access data in a high capacity environment. To cater to these modern users, the Minnesota Supercomputing Institute designed and deployed Stratus, a locally-hosted cloud environment powered by the OpenStack platform, and backed by Ceph storage. The subscription-based service complements existing HPC systems by satisfying the following unmet needs of our users: a) on-demand availability of compute resources; b) long-running jobs (i.e., 30 days); c) container-based computing with Docker; and d) adequate security controls to comply with controlled-access data requirements. This document provides an in-depth look at the design of Stratus with respect to security and compliance with the NIH's controlled-access data policy. Emphasis is placed on lessons learned while integrating OpenStack and Ceph features into a so-called "walled garden", and how those technologies influenced the security design. Many features of Stratus, including tiered secure storage with the introduction of a controlled-access data "cache", fault-tolerant live-migrations, and fully integrated two-factor authentication, depend on recent OpenStack and Ceph features.

Cox, Jr., Jacob H., Clark, Russell J., Owen, III, Henry L..  2016.  Leveraging SDN to Improve the Security of DHCP. Proceedings of the 2016 ACM International Workshop on Security in Software Defined Networks & Network Function Virtualization. :35–38.

Current State of the art technologies for detecting and neutralizing rogue DHCP servers are tediously complex and prone to error. Network operators can spend hours (even days) before realizing that a rogue server is affecting their network. Additionally, once network operators suspect that a rogue server is active on their network, even more hours can be spent finding the server's MAC address and preventing it from affecting other clients. Not only are such methods slow to eliminate rogue servers, they are also likely to affect other clients as network operators shutdown services while attempting to locate the server. In this paper, we present Network Flow Guard (NFG), a simple security application that utilizes the software defined networking (SDN) paradigm of programmable networks to detect and disable rogue servers before they are able to affect network clients. Consequently, the key contributions of NFG are its modular approach and its automated detection/prevention of rogue DHCP servers, which is accomplished with little impact to network architecture, protocols, and network operators.

Izurieta, Clemente, Prouty, Mary.  2019.  Leveraging SecDevOps to Tackle the Technical Debt Associated with Cybersecurity Attack Tactics. 2019 IEEE/ACM International Conference on Technical Debt (TechDebt). :33–37.
Context: Managing technical debt (TD) associated with external cybersecurity attacks on an organization can significantly improve decisions made when prioritizing which security weaknesses require attention. Whilst source code vulnerabilities can be found using static analysis techniques, malicious external attacks expose the vulnerabilities of a system at runtime and can sometimes remain hidden for long periods of time. By mapping malicious attack tactics to the consequences of weaknesses (i.e. exploitable source code vulnerabilities) we can begin to understand and prioritize the refactoring of the source code vulnerabilities that cause the greatest amount of technical debt on a system. Goal: To establish an approach that maps common external attack tactics to system weaknesses. The consequences of a weakness associated with a specific attack technique can then be used to determine the technical debt principal of said violation; which can be measured in terms of loss of business rather than source code maintenance. Method: We present a position study that uses Jaccard similarity scoring to examine how 11 malicious attack tactics can relate to Common Weakness Enumerations (CWEs). Results: We conduct a study to simulate attacks, and generate dependency graphs between external attacks and the technical consequences associated with CWEs. Conclusion: The mapping of cyber security attacks to weaknesses allows operational staff (SecDevOps) to focus on deploying appropriate countermeasures and allows developers to focus on refactoring the vulnerabilities with the greatest potential for technical debt.
von Maltitz, Marcel, Carle, Georg.  2018.  Leveraging Secure Multiparty Computation in the Internet of Things. Proceedings of the 16th Annual International Conference on Mobile Systems, Applications, and Services. :508–510.
Centralized systems in the Internet of Things—be it local middleware or cloud-based services—fail to fundamentally address privacy of the collected data. We propose an architecture featuring secure multiparty computation at its core in order to realize data processing systems which already incorporate support for privacy protection in the architecture.
Washha, Mahdi, Qaroush, Aziz, Sedes, Florence.  2016.  Leveraging Time for Spammers Detection on Twitter. Proceedings of the 8th International Conference on Management of Digital EcoSystems. :109–116.

Twitter is one of the most popular microblogging social systems, which provides a set of distinctive posting services operating in real time. The flexibility of these services has attracted unethical individuals, so-called "spammers", aiming at spreading malicious, phishing, and misleading information. Unfortunately, the existence of spam results non-ignorable problems related to search and user's privacy. In the battle of fighting spam, various detection methods have been designed, which work by automating the detection process using the "features" concept combined with machine learning methods. However, the existing features are not effective enough to adapt spammers' tactics due to the ease of manipulation in the features. Also, the graph features are not suitable for Twitter based applications, though the high performance obtainable when applying such features. In this paper, beyond the simple statistical features such as number of hashtags and number of URLs, we examine the time property through advancing the design of some features used in the literature, and proposing new time based features. The new design of features is divided between robust advanced statistical features incorporating explicitly the time attribute, and behavioral features identifying any posting behavior pattern. The experimental results show that the new form of features is able to classify correctly the majority of spammers with an accuracy higher than 93% when using Random Forest learning algorithm, applied on a collected and annotated data-set. The results obtained outperform the accuracy of the state of the art features by about 6%, proving the significance of leveraging time in detecting spam accounts.

Hoshida, Masahiro, Tamura, Masahiko, Hayashi, Yugo.  2017.  Lexical Entrainment Toward Conversational Agents: An Experimental Study on Top-down Processing and Bottom-up Processing. Proceedings of the 5th International Conference on Human Agent Interaction. :189–194.

The purpose of this paper is to examine the influence of lexical entrainment while communicating with a conversational agent. We consider two types of cognitive information processing:top-down processing, which depends on prior knowledge, and bottom-up processing, which depends on one's partners' behavior. Each works mutually complementarily in interpersonal cognition. It was hypothesized that we will separate each method of processing because of the agent's behavior. We designed a word choice task where participants and the agent described pictures and selected them alternately and held two factors constant:First, the expectation about the agent's intelligence by the experimenter's instruction as top-down processing; second, the agent's behavior, manipulating the degree of intellectual impression, as bottom-up processing. The results show that people select words differently because of the diversity of expressed behavior and thus supported our hypothesis. The findings obtained in this study could bring about new guidelines for a human-to-agent language interface.

Zhang, F., Chan, P. P. K., Tang, T. Q..  2015.  L-GEM based robust learning against poisoning attack. 2015 International Conference on Wavelet Analysis and Pattern Recognition (ICWAPR). :175–178.

Poisoning attack in which an adversary misleads the learning process by manipulating its training set significantly affect the performance of classifiers in security applications. This paper proposed a robust learning method which reduces the influences of attack samples on learning. The sensitivity, defined as the fluctuation of the output with small perturbation of the input, in Localized Generalization Error Model (L-GEM) is measured for each training sample. The classifier's output on attack samples may be sensitive and inaccurate since these samples are different from other untainted samples. An import score is assigned to each sample according to its localized generalization error bound. The classifier is trained using a new training set obtained by resampling the samples according to their importance scores. RBFNN is applied as the classifier in experimental evaluation. The proposed model outperforms than the traditional one under the well-known label flip poisoning attacks including nearest-first and farthest-first flips attack.

Gaber, C., Vilchez, J. S., Gür, G., Chopin, M., Perrot, N., Grimault, J.-L., Wary, J.-P..  2020.  Liability-Aware Security Management for 5G. 2020 IEEE 3rd 5G World Forum (5GWF). :133—138.

Multi-party and multi-layer nature of 5G networks implies the inherent distribution of management and orchestration decisions across multiple entities. Therefore, responsibility for management decisions concerning end-to-end services become blurred if no efficient liability and accountability mechanism is used. In this paper, we present the design, building blocks and challenges of a Liability-Aware Security Management (LASM) system for 5G. We describe how existing security concepts such as manifests and Security-by-Contract, root cause analysis, remote attestation, proof of transit, and trust and reputation models can be composed and enhanced to take risk and responsibilities into account for security and liability management.

Aublin, Pierre-Louis, Kelbert, Florian, O'Keeffe, Dan, Muthukumaran, Divya, Priebe, Christian, Lind, Joshua, Krahn, Robert, Fetzer, Christof, Eyers, David, Pietzuch, Peter.  2018.  LibSEAL: Revealing Service Integrity Violations Using Trusted Execution. Proceedings of the Thirteenth EuroSys Conference. :24:1–24:15.
Users of online services such as messaging, code hosting and collaborative document editing expect the services to uphold the integrity of their data. Despite providers' best efforts, data corruption still occurs, but at present service integrity violations are excluded from SLAs. For providers to include such violations as part of SLAs, the competing requirements of clients and providers must be satisfied. Clients need the ability to independently identify and prove service integrity violations to claim compensation. At the same time, providers must be able to refute spurious claims. We describe LibSEAL, a SEcure Audit Library for Internet services that creates a non-repudiable audit log of service operations and checks invariants to discover violations of service integrity. LibSEAL is a drop-in replacement for TLS libraries used by services, and thus observes and logs all service requests and responses. It runs inside a trusted execution environment, such as Intel SGX, to protect the integrity of the audit log. Logs are stored using an embedded relational database, permitting service invariant violations to be discovered using simple SQL queries. We evaluate LibSEAL with three popular online services (Git, ownCloud and Dropbox) and demonstrate that it is effective in discovering integrity violations, while reducing throughput by at most 14%.
Soni, G., Sudhakar, R..  2020.  A L-IDS against Dropping Attack to Secure and Improve RPL Performance in WSN Aided IoT. 2020 7th International Conference on Signal Processing and Integrated Networks (SPIN). :377—383.

In the Internet of Things (IoT), it is feasible to interconnect networks of different devices and all these different devices, such as smartphones, sensor devices, and vehicles, are controlled according to a particular user. These different devices are delivered and accept the information on the network. This thing is to motivate us to do work on IoT and the devices used are sensor nodes. The validation of data delivery completely depends on the checks of count data forwarding in each node. In this research, we propose the Link Hop Value-based Intrusion Detection System (L-IDS) against the blackhole attack in the IoT with the assist of WSN. The sensor nodes are connected to other nodes through the wireless link and exchange data routing, as well as data packets. The LHV value is identified as the attacker's presence by integrating the data delivery in each hop. The LHV is always equivalent to the Actual Value (AV). The RPL routing protocol is used IPv6 to address the concept of routing. The Routing procedure is interrupted by an attacker by creating routing loops. The performance of the proposed L-IDS is compared to the RPL routing security scheme based on existing trust. The proposed L-IDS procedure is validating the presence of the attacker at every source to destination data delivery. and also disables the presence of the attacker in the network. Network performance provides better results in the existence of a security scheme and also fully represents the inoperative presence of black hole attackers in the network. Performance metrics show better results in the presence of expected IDS and improve network reliability.

Pandey, S.K., Mehtre, B.M..  2014.  A Lifecycle Based Approach for Malware Analysis. Communication Systems and Network Technologies (CSNT), 2014 Fourth International Conference on. :767-771.

Most of the detection approaches like Signature based, Anomaly based and Specification based are not able to analyze and detect all types of malware. Signature-based approach for malware detection has one major drawback that it cannot detect zero-day attacks. The fundamental limitation of anomaly based approach is its high false alarm rate. And specification-based detection often has difficulty to specify completely and accurately the entire set of valid behaviors a malware should exhibit. Modern malware developers try to avoid detection by using several techniques such as polymorphic, metamorphic and also some of the hiding techniques. In order to overcome these issues, we propose a new approach for malware analysis and detection that consist of the following twelve stages Inbound Scan, Inbound Attack, Spontaneous Attack, Client-Side Exploit, Egg Download, Device Infection, Local Reconnaissance, Network Surveillance, & Communications, Peer Coordination, Attack Preparation, and Malicious Outbound Propagation. These all stages will integrate together as interrelated process in our proposed approach. This approach had solved the limitations of all the three approaches by monitoring the behavioral activity of malware at each any every stage of life cycle and then finally it will give a report of the maliciousness of the files or software's.

Park, Chan Mi, Lee, Jung Yeon, Baek, Hyoung Woo, Lee, Hae-Sung, Lee, JeeHang, Kim, Jinwoo.  2019.  Lifespan Design of Conversational Agent with Growth and Regression Metaphor for the Natural Supervision on Robot Intelligence. 2019 14th ACM/IEEE International Conference on Human-Robot Interaction (HRI). :646–647.
Human's direct supervision on robot's erroneous behavior is crucial to enhance a robot intelligence for a `flawless' human-robot interaction. Motivating humans to engage more actively for this purpose is however difficult. To alleviate such strain, this research proposes a novel approach, a growth and regression metaphoric interaction design inspired from human's communicative, intellectual, social competence aspect of developmental stages. We implemented the interaction design principle unto a conversational agent combined with a set of synthetic sensors. Within this context, we aim to show that the agent successfully encourages the online labeling activity in response to the faulty behavior of robots as a supervision process. The field study is going to be conducted to evaluate the efficacy of our proposal by measuring the annotation performance of real-time activity events in the wild. We expect to provide a more effective and practical means to supervise robot by real-time data labeling process for long-term usage in the human-robot interaction.
Uyan, O. Gokhan, Gungor, V. Cagri.  2019.  Lifetime Analysis of Underwater Wireless Networks Concerning Privacy with Energy Harvesting and Compressive Sensing. 2019 27th Signal Processing and Communications Applications Conference (SIU). :1–4.
Underwater sensor networks (UWSN) are a division of classical wireless sensor networks (WSN), which are designed to accomplish both military and civil operations, such as invasion detection and underwater life monitoring. Underwater sensor nodes operate using the energy provided by integrated limited batteries, and it is a serious challenge to replace the battery under the water especially in harsh conditions with a high number of sensor nodes. Here, energy efficiency confronts as a very important issue. Besides energy efficiency, data privacy is another essential topic since UWSN typically generate delicate sensing data. UWSN can be vulnerable to silent positioning and listening, which is injecting similar adversary nodes into close locations to the network to sniff transmitted data. In this paper, we discuss the usage of compressive sensing (CS) and energy harvesting (EH) to improve the lifetime of the network whilst we suggest a novel encryption decision method to maintain privacy of UWSN. We also deploy a Mixed Integer Programming (MIP) model to optimize the encryption decision cases which leads to an improved network lifetime.
Nie, Chuanyao, Wu, Hui, Zheng, Wenguang.  2017.  Lifetime-Aware Data Collection Using a Mobile Sink in WSNs with Unreachable Regions. Proceedings of the 20th ACM International Conference on Modelling, Analysis and Simulation of Wireless and Mobile Systems. :143–152.

Using mobile sinks to collect sensed data in WSNs (Wireless Sensor Network) is an effective technique for significantly improving the network lifetime. We investigate the problem of collecting sensed data using a mobile sink in a WSN with unreachable regions such that the network lifetime is maximized and the total tour length is minimized, and propose a polynomial-time heuristic, an ILP-based (Integer Linear Programming) heuristic and an MINLP-based (Mixed-Integer Non-Linear Programming) algorithm for constructing a shortest path routing forest for the sensor nodes in unreachable regions, two energy-efficient heuristics for partitioning the sensor nodes in reachable regions into disjoint clusters, and an efficient approach to convert the tour construction problem into a TSP (Travelling Salesman Problem). We have performed extensive simulations on 100 instances with 100, 150, 200, 250 and 300 sensor nodes in an urban area and a forest area. The simulation results show that the average lifetime of all the network instances achieved by the polynomial-time heuristic is 74% of that achieved by the ILP-based heuristic and 65% of that obtained by the MINLP-based algorithm, and our tour construction heuristic significantly outperforms the state-of-the-art tour construction heuristic EMPS.

Wang, Ju, Jiang, Hongbo, Xiong, Jie, Jamieson, Kyle, Chen, Xiaojiang, Fang, Dingyi, Xie, Binbin.  2016.  LiFS: Low Human-effort, Device-free Localization with Fine-grained Subcarrier Information. Proceedings of the 22Nd Annual International Conference on Mobile Computing and Networking. :243–256.

Device-free localization of people and objects indoors not equipped with radios is playing a critical role in many emerging applications. This paper presents an accurate model-based device-free localization system LiFS, implemented on cheap commercial off-the-shelf (COTS) Wi-Fi devices. Unlike previous COTS device-based work, LiFS is able to localize a target accurately without offline training. The basic idea is simple: channel state information (CSI) is sensitive to a target's location and by modelling the CSI measurements of multiple wireless links as a set of power fading based equations, the target location can be determined. However, due to rich multipath propagation indoors, the received signal strength (RSS) or even the fine-grained CSI can not be easily modelled. We observe that even in a rich multipath environment, not all subcarriers are affected equally by multipath reflections. Our pre-processing scheme tries to identify the subcarriers not affected by multipath. Thus, CSIs on the "clean" subcarriers can be utilized for accurate localization. We design, implement and evaluate LiFS with extensive experiments in three different environments. Without knowing the majority transceivers' locations, LiFS achieves a median accuracy of 0.5 m and 1.1 m in line-of-sight (LoS) and non-line-of-sight (NLoS) scenarios respectively, outperforming the state-of-the-art systems. Besides single target localization, LiFS is able to differentiate two sparsely-located targets and localize each of them at a high accuracy.

Maurice Heemels, Geir Dullerud, University of Illinois at Urbana-Champaign, Andrew Teel.  2015.  A Lifting Approach to L2-gain Analysis of Periodic Event-triggered and Switching Sampled-data Control Systems. IEEE International Conference on Decision and Control (CDC 2015).

In this work we are interested in the stability and L2-gain of hybrid systems with linear flow dynamics, periodic time-triggered jumps and nonlinear possibly set-valued jump maps. This class of hybrid systems includes various interesting applications such as periodic event-triggered control. In this paper we also show that sampled-data systems with arbitrarily switching controllers can be captured in this framework by requiring the jump map to be set-valued. We provide novel conditions for the internal stability and L2-gain analysis of these systems adopting a lifting-based approach. In particular, we establish that the internal stability and contractivity in terms of an L2-gain smaller than 1 are equivalent to the internal stability and contractivity of a particular discretetime set-valued nonlinear system. Despite earlier works in this direction, these novel characterisations are the first necessary and sufficient conditions for the stability and the contractivity of this class of hybrid systems. The results are illustrated through multiple new examples.