#### Electrical and Electronics Engineering publications abstract of: 07-2017 sorted by title, page: 9

» Intensive Study of Skin Effect in Eddy Current Testing With Pancake Coil
 Abstract:Skin depth is an important parameter that quantifies depth of inspection of eddy current (EC) nondestructive testing. The formula which states that the skin depth is inversely proportional to the square root of the product of frequency, permeability, and conductivity has been widely used for calculating skin depth for many decades. It has been noticed that the true skin depth is less than that obtained by the formula when the EC is excited by the ac current in a pancake coil. In-depth and convincible explanation of this discrepancy has not been published. This paper studies this problem by finite-element analysis and concludes that the difference is due to two reasons. One is that the EC associated with pancake coil diffuses with increasing depth, whereas there is no diffusion effect of EC associated with uniform plane field which is the assumption of the conventional formula. The other reason is that the ECs induced by wire segments symmetric about the coil axis cancel each other and the cancellation becomes more severe with increasing depth due to the diffusion of EC. This paper also investigates the influence of each of coil parameters on skin depth. Then, a new formula for estimating skin depth is proposed. Autors: Shaoni Jiao;Xiaohua Liu;Zhiwei Zeng; Appeared in: IEEE Transactions on Magnetics Publication date: Jul 2017, volume: 53, issue:7, pages: 1 - 8 Publisher: IEEE
» Interactive Magnetic Catheter Steering With 3-D Real-Time Feedback Using Multi-Color Magnetic Particle Imaging
 Abstract:Magnetic particle imaging (MPI) is an emerging tomographic method that enables sensitive and fast imaging. It does not require ionizing radiation and thus may be a safe alternative for tracking of devices in the catheterization laboratory. The 3-D real-time imaging capabilities of MPI have been demonstrated in vivo and recent improvements in fast online image reconstruction enable almost real-time data reconstruction and visualization. Moreover, based on the use of different magnetic particle types for catheter visualization and blood pool imaging, multi-color MPI enables reconstruction of separate images for the catheter and the vessels from simultaneously measured data. While these are important assets for interventional imaging, MPI field generators can furthermore apply strong forces on a magnetic catheter tip. It is the aim of this paper to give a first demonstration of the combination of real-time multi-color MPI with online reconstruction and interactive field control for the application of forces on a magnetic catheter model in a phantom experiment. Autors: Jürgen Rahmer;Daniel Wirtz;Claas Bontus;Jörn Borgert;Bernhard Gleich; Appeared in: IEEE Transactions on Medical Imaging Publication date: Jul 2017, volume: 36, issue:7, pages: 1449 - 1456 Publisher: IEEE
» Interactive Video Segmentation via Local Appearance Model
 Abstract:In numerous video segmentation algorithms, shape and color priors from previous frames are propagated to successive frames for processing. One prime issue of the existing algorithms is how priors are modeled and propagated effectively. This paper proposes a novel algorithm for accurate and robust foreground prediction via a local appearance model based on shape and color. In the shape estimation process, instead of performing global matching, a local search mechanism is developed to capture complex motions. In addition, global information is used to facilitate local matching for the final shape estimation. Color cues from multiple frames are used to estimate the foreground (background) pixel distribution in the current image. Furthermore, the contribution of each frame is weighted based on its reliability and discriminative strength. Based on the proposed local appearance model, a graph cut algorithm is used to generate segmentation results. The experimental results show that accurate video segmentation can be obtained by the proposed algorithm with fewer user interactions. Autors: Chong Sun;Huchuan Lu; Appeared in: IEEE Transactions on Circuits and Systems for Video Technology Publication date: Jul 2017, volume: 27, issue:7, pages: 1491 - 1501 Publisher: IEEE
» Interference Constraint Active Learning with Uncertain Feedback for Cognitive Radio Networks
 Abstract:In this paper, an intelligent probing method for interference constraint learning is proposed to allow a centralized cognitive radio network (CRN) to access the frequency band of a primary user (PU) in an underlay cognitive communication scenario. The main idea is that the CRN probes the PU and subsequently eavesdrops the reverse PU link to acquire the binary ACK/NACK packet. This feedback is implicit channel state information of the PU link, indicating whether the probing-induced interference is harmful or not. The intelligence of this sequential probing process lies in the selection of the power levels of the secondary users, which aims to minimize the number of probing attempts, a clearly active learning (AL) procedure, and expectantly the overall PU QoS degradation. The enhancement introduced in this paper is that we incorporate the probability of each feedback being correct into this intelligent probing mechanism by using a multivariate Bayesian AL method. This technique is inspired by the probabilistic bisection algorithm and the deterministic cutting plane methods (CPMs). The optimality of this multivariate Bayesian AL method is proven and its effectiveness is demonstrated through numerical simulations. Computationally cheap CPM adaptations are also presented, which outperform existing AL methods. Autors: Anestis Tsakmalis;Symeon Chatzinotas;Björn Ottersten; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4654 - 4668 Publisher: IEEE
» Interference Resilient Duty Cycling for Sensor Networks Under Co-Existing Environments
 Abstract:To save energy, wireless sensor networks often run in a low-duty-cycle mode, where the radios of sensor nodes are scheduled between ON and OFF states. For nodes to communicate with each other, low power listening (LPL) and low power probing (LPP) are two types of rendezvous mechanisms. Nodes with LPL or LPP rely on signal strength or probe packets to detect potential transmissions, and then keep the radio-ON for communications. Unfortunately, in co-existing environments, signal strength and probe packets are susceptible to interference, resulting in undesirable radio ON time when the signal strength of interference is above a threshold or a probe packet is interfered. To address the issue, we propose ZiSense, a low duty cycling mechanism resilient to interference. Instead of checking the signal strength or decoding the probe packets, ZiSense detects the ZigBee signals and wakes up nodes accordingly. On sensor nodes with limited information and resource, we carefully study and extract short-term features purely from the time-domain RSSI sequence, and design a rule-based approach to efficiently identify the existence of ZigBee. We theoretically analyze the benefit of ZiSense in different environments and implement a prototype in TinyOS with TelosB motes. We examine ZiSense performance under controlled interference and office environments. The evaluation results show that, compared with the state-of-the-art rendezvous mechanisms, ZiSense significantly reduces the energy consumption. Autors: Xiaolong Zheng;Zhichao Cao;Jiliang Wang;Yuan He;Yunhao Liu; Appeared in: IEEE Transactions on Communications Publication date: Jul 2017, volume: 65, issue:7, pages: 2971 - 2984 Publisher: IEEE
» Intermittent Communication
 Abstract:We formulate a model for intermittent communication that can capture bursty transmissions or a sporadically available channel, where in either case the receiver does not know when the transmissions will occur. Focusing on the point-to-point case, we develop a decoding structure, decoding from pattern detection, and its achievable rate for such communication scenarios. Decoding from pattern detection first detects the locations of code word symbols and then uses them to decode. We introduce the concept of partial divergence and study some of its properties in order to obtain stronger achievability results. As the system becomes more intermittent, the achievable rates decrease due to the additional uncertainty about the positions of the code word symbols at the decoder. In addition, we provide upper bounds on the capacity of binary noiseless intermittent communication with the help of a genie-aided encoder and decoder. The upper bounds imply a tradeoff between the capacity and the intermittency rate of the communication system, even if the receive window scales linearly with the code word length. Autors: Mostafa Khoshnevisan;J. Nicholas Laneman; Appeared in: IEEE Transactions on Information Theory Publication date: Jul 2017, volume: 63, issue:7, pages: 4089 - 4102 Publisher: IEEE
» Intra Line Copy for HEVC Screen Content Intra-Picture Prediction
 Abstract:This paper presents an intra line copy (ILC) technique for HEVC screen content coding. It shares the same origin with two other prominent techniques, intra string copy (ISC) and intra block copy (IBC), in applying the notion of string matching to intra-frame coding. This work combines their merits in one scheme with both good compression performance and high regularity. Specifically, it forms a prediction of a coding block by decomposing it into horizontal or vertical lines of pixels and performing line-based predictions based on previously coded data from the current frame. To address the massive amounts of search operations, our fast search algorithm first searches in the horizontal and vertical directions, then checks line vector candidates from spatial and temporal neighbors, and finally references lines having an identical hash value as the prediction line. The resulting line vectors are further predicted adaptively to minimize their coding overhead. Extensive experiments based on SCM-4.0, which includes IBC as an integral component, show that ILC can provide an additional 4%–7% BD-rate savings when the search area extends to the entire frame and 3%–4% improvements with a restricted local search. Compared with ISC, it achieves comparable performance without all its complications from sequential string parsing. Autors: Chun-Chi Chen;Wen-Hsiao Peng; Appeared in: IEEE Transactions on Circuits and Systems for Video Technology Publication date: Jul 2017, volume: 27, issue:7, pages: 1568 - 1579 Publisher: IEEE
» Introduction to the Special Issue on the 46th European Solid-State Circuits Conference (ESSCIRC)
 Abstract:Welcome to this special issue of the journal covering the 46th European Solid-State Circuits Conference, ESSCIRC 2016. The conference was held in Lausanne, Switzerland, September 13–15, 2016. From the 94 papers presented at the conference, a selection of 21 papers was made for inclusion in this special issue. As Guest Editors, we have used the inputs of the technical program committee and the session chairs, as well as the audience ratings. The selected papers are briefly introduced below. Autors: Eugenio Cantatore;Wim Dehaene;Robert Bogdan Staszewski; Appeared in: IEEE Journal of Solid-State Circuits Publication date: Jul 2017, volume: 52, issue:7, pages: 1700 - 1702 Publisher: IEEE
» Investigation of DC-Link Voltage and Temperature Variations on EV Traction System Design
 Abstract:DC-link voltage and temperature variations are critical issues when designing an electric vehicle (EV) traction system. However, systems are generally reported at fixed voltage and temperature and may not, therefore, be fully specified when considering the variation of these parameters over full vehicle operating extremes. This paper presents an assessment of power-train options based on the Nissan Leaf vehicle, which is taken as a benchmark system providing experimental validation of the study results. The Nissan Leaf traction machine is evaluated and performance assessed by considering dc-link voltage and temperature variations typical of an automotive application, showing that the system lacks performance as battery state of charge decreases. An alternative traction machine design is proposed to satisfy the target performance. The vehicle power-train is then modified with the inclusion of a dc/dc converter between the vehicle battery and dc-link to maintain the traction system dc-link voltage near constant. A supercapacitor system is also considered for improved system voltage management. The trade-offs for the redesigned systems are discussed in terms of electronic and machine packaging, and mitigation of faulted operation at high speeds. Autors: Nan Zhao;Nigel Schofield;Rong Yang;Ran Gu; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3707 - 3718 Publisher: IEEE
» Investigation of the Depth Reconstruction and Search for Local Performance Variations With a Large Coplanar-Quad-Grid CdZnTe Detector
 Abstract:CdZnTe coplanar-grid (CPG) detector is used in the COBRA experiment to search for neutrinoless double beta decay. In the next phase of the experiment, significantly larger detectors with a volume of and a coplanar-quad-grid will be used. This paper presents the results of a spatially resolved investigation of the performance of one detector of this type, focusing on its usability in a double-beta experiment. With these data, two modifications of the interaction depth formula, which is of great importance for background reduction in COBRA, are investigated for the first time with such a detector, and the results are compared with a detector with a conventional CPG. Furthermore, we report the mobility-lifetime product for electrons for each sector of the detector. Autors: Robert Temminghoff; Appeared in: IEEE Transactions on Nuclear Science Publication date: Jul 2017, volume: 64, issue:7, pages: 1934 - 1941 Publisher: IEEE
» It Can Drain Out Your Energy: An Energy-Saving Mechanism Against Packet Overhearing in High Traffic Wireless LANs
 Abstract:Energy efficiency is a critical issue of wireless devices. As the packets are broadcast to the devices in the wireless transmission media, all active neighboring devices have to spend their energy receiving the packets though the packets are not addressed to them, which is called as the packet overhearing problem. The real-world traffic trace analysis reveals that the energy cost on the packet overhearing accounts for the majority of the devices' energy inefficiency in high traffic wireless local area networks (WLANs). In this paper, we propose a novel sample-address sample-duration (SASD) scheme to solve the energy inefficiency of the packet overhearing problem. By adding a new SASD header, which contains the critical information, in front of the data packet at the physical layer, the SASD enables the devices to discern the required information in the energy-saving downclocking mode. Consequently, the non-destination devices of the packet can switch to the sleeping mode to avoid the packet overhearing problem. We demonstrate the feasibility of the SASD through hardware experiments and evaluate its energy-saving performance through ns-2 simulations. The results show that the SASD can greatly outperform the existing approaches in the high traffic WLAN scenario. Autors: Tao Xiong;Junmei Yao;Jin Zhang;Wei Lou; Appeared in: IEEE Transactions on Mobile Computing Publication date: Jul 2017, volume: 16, issue:7, pages: 1911 - 1925 Publisher: IEEE
» It was Really Lagniappe!: Highlights from ICASSP 2017 in New Orleans [Conference Highlights]
 Abstract:Presents highlights from the ICASSP 2017 Conference. Autors: Magdy Bayoumi; Appeared in: IEEE Signal Processing Magazine Publication date: Jul 2017, volume: 34, issue:4, pages: 188 - 191 Publisher: IEEE
» Iterative Hybrid Precoder and Combiner Design for mmWave Multiuser MIMO Systems
 Abstract:This letter investigates analog/digital hybrid precoder and combiner design for millimeter wave (mmWave) multiuser multiple-input multiple-output (MU-MIMO) systems. We propose a novel iterative algorithm for the joint hybrid precoder and combiner design by exploiting the duality of the uplink and downlink MU-MIMO channels. For the initialization stage, the proposed algorithm selects the analog precoder-combiner pair based on the orthogonal matching pursuit (OMP) algorithm to enhance the channel gain, while mitigating the multiple access interference, and obtains the digital combiner via minimum mean square error criterion. Then, the proposed algorithm enhances the performance gradually at each iteration via joint design of the uplink and downlink precoders/combiners. Simulation results demonstrate the significant performance advantages of the proposed precoder and combiner design compared with existing hybrid beamforming algorithms. Autors: Zihuan Wang;Ming Li;Xiaowen Tian;Qian Liu; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1581 - 1584 Publisher: IEEE
» Iterative Learning and Extremum Seeking for Repetitive Time-Varying Mappings
 Abstract:In this paper, we develop an iterative learning control method integrated with extremum seeking control to track a time-varying optimizer within finite time horizon. The behavior of the extremum seeking system is analyzed via an approximating system—the modified Lie bracket system. The modified Lie bracket system is essentially an online integral-type iterative learning control law. The paper contributes to two fields, namely, iterative learning control and extremum seeking. First, an online integral type iterative learning control with a forgetting factor is proposed. Its convergence is analyzed via -dependent (iteration-dependent) contraction mapping in a Banach space equipped with so called -norm. Second, the iterative learning extremum seeking system can be interpreted as an iterative learning control with the approximation error as “disturbance”. The tracking error of its modified Lie bracket system can be shown uniformly bounded in terms of iterations by selecting a sufficiently large dither frequency. Furthermore, it is shown that the tracking error will eventually converge to a set. The center of the set corresponds to the limit solution of the “disturbance-free” system, and its radius can be controlled by the frequency. Autors: Zhixing Cao;Hans-Bernd Dürr;Christian Ebenbauer;Frank Allgöwer;Furong Gao; Appeared in: IEEE Transactions on Automatic Control Publication date: Jul 2017, volume: 62, issue:7, pages: 3339 - 3353 Publisher: IEEE
» Jamming Attack Model and Detection Method for Beacons Under Multichannel Operation in Vehicular Networks
 Abstract:Safety applications in vehicular networks involve real-time information included in periodical exchanged messages, called beacons. Denial of Service (DoS) attacks, especially jamming, may have high impact on these basic safety messages mainly because of the adequate condition of the attack at the lower layers. Due to the important role of these safety messages, securing beacons against jamming attacks is primordial. First, we investigate the impact of jamming attacks on broadcasting by introducing a new analytical model. We show that the degradation at certain levels in network performance is an indication of a jamming attack in the network; therefore, results from this analysis will allow us to determine network performance thresholds to distinguish normal operation and attacks. Second, we study the feasibility of the existing threshold-based methods to detect jamming in real-time applications. From our analysis, these methods are not suitable for safety applications. Hence, we propose a real-time Medium-Access-Control-based (MAC-based) detection method detection method to meet the requirements of safety applications in vehicular networks. Our detection method can more accurately distinguish the causes of failed transmissions, such as contention collisions, interferences, and jamming attacks. The jamming attacks are detected with low probability of false alarms. Finally, we evaluate our detection method with both analytical analysis and network simulations. Our detection method performs high detection probability in different studied scenarios while false alarms are almost avoided. Autors: Abderrahim Benslimane;Huong Nguyen-Minh; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6475 - 6488 Publisher: IEEE
» JAMMY: A Distributed and Dynamic Solution to Selective Jamming Attack in TDMA WSNs
 Abstract:Time division multiple access (TDMA) is often used in wireless sensor networks (WSNs), especially for critical applications, as it provides high energy efficiency, guaranteed bandwidth, bounded and predictable latency, and absence of collisions. However, TDMA is vulnerable to selective jamming attacks. In TDMA transmission, slots are typically pre-allocated to sensor nodes, and each slot is used by the same node for a number of consecutive superframes. Hence, an adversary could thwart a victim node’s communication by simply jamming its slot(s). Such attack turns out to be effective, energy efficient, and extremely difficult to detect. In this paper, we present JAMMY, a distributed and dynamic solution to selective jamming in TDMA-based WSNs. Unlike traditional approaches, JAMMY changes the slot utilization pattern at every superframe, thus making it unpredictable to the adversary. JAMMY is decentralized, as sensor nodes determine the next slot utilization pattern in a distributed and autonomous way. Results from performance analysis of the proposed solution show that JAMMY introduces negligible overhead yet allows multiple nodes to join the network, in a limited number of superframes. Autors: Marco Tiloca;Domenico De Guglielmo;Gianluca Dini;Giuseppe Anastasi;Sajal K. Das; Appeared in: IEEE Transactions on Dependable and Secure Computing Publication date: Jul 2017, volume: 14, issue:4, pages: 392 - 405 Publisher: IEEE
» John T. Barr IV Named MTT-S Honorary Life Member [Awards]
 Abstract:Presents the recipient of the IEEE MTT-S Honorary Life Member. Autors: Peter W Staecker; Appeared in: IEEE Microwave Magazine Publication date: Jul 2017, volume: 18, issue:5, pages: 106 - 132 Publisher: IEEE
» Joint Antenna Selection and Spatial Switching for Energy Efficient MIMO SWIPT System
 Abstract:In this paper, we investigate joint antenna selection and spatial switching for quality-of-service-constrained energy efficiency (EE) optimization in a multiple-input multiple-output simultaneous wireless information and power transfer system. A practical linear power model taking into account the entire transmit–receive chain is accordingly utilized. The corresponding fractional-combinatorial and non-convex EE problem, involving joint optimization of eigenchannel assignment, power allocation, and active receive antenna set selection, subject to satisfying minimum sum-rate and power transfer constraints, is extremely difficult to solve directly. In order to tackle this, we separate the eigenchannel assignment and power allocation procedure with the antenna selection functionality. In particular, we first tackle the EE maximization problem under fixed receive antenna set using Dinkelbach-based convex programming, iterative joint eigenchannel assignment and power allocation, and low-complexity multi-objective optimization-based approach. On the other hand, the number of active receive antennas induces a tradeoff in the achievable sum-rate and power transfer versus the transmit-independent power consumption. We provide a fundamental study of the achievable EE with antenna selection and accordingly develop dynamic optimal exhaustive search and Frobenius-norm-based schemes. Simulation results confirm the theoretical findings and demonstrate that the proposed resource allocation algorithms can efficiently approach the optimal EE. Autors: Jie Tang;Daniel K. C. So;Arman Shojaeifard;Kai-Kit Wong;Jinming Wen; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4754 - 4769 Publisher: IEEE
» Joint Cell Zooming and Channel Allocation Using C-SAP for Large Action Sets
 Abstract:Optimizing energy consumption is paramount to sustain the growth of cellular networks. One of the approaches to reduce energy consumption is traffic dependent operation of networks. The traffic demand experienced by the network fluctuates over the duration of a day. Therefore, during the periods of low traffic, we may re-configure the network to trade the excess capacity for energy reduction. For example, we may modulate the BS transmit power (Cell Zooming) so as to maintain the desired QoS. However, determining an optimal network configuration is known to be computationally hard. Along with Cell Zooming, it is essential to also consider channel re-assignment, for, when the transmit powers of BSs are changed, the channels allocated to BSs must also be suitably changed. Considering therefore channel allocations also as state variables, the search space over which the optimization should be performed blows up, further complicating the problem. In this paper, we propose a framework to address this problem. The proposed algorithm is suitable for such large search spaces, while the framework is general enough to admit several QoS requirements and sophisticated power consumption models. The underlying mathematical formulation is also applicable in other contexts, and is of independent interest as well. Autors: Karunakaran Kumar;Prasanna Chaporkar;Abhay Karandikar; Appeared in: IEEE Transactions on Mobile Computing Publication date: Jul 2017, volume: 16, issue:7, pages: 1926 - 1939 Publisher: IEEE
» Joint Energy-Spectral-Efficiency Optimization of CoMP and BS Deployment in Dense Large-Scale Cellular Networks
 Abstract:In this paper, the energy-spectral efficiency (ESE) benefiting from the joint optimization of coordinated multi-point (CoMP) transmission and base station (BS) deployment is evaluated in the context of dense large-scale cellular network. We first derive a closed-form network ESE expression for a large-scale CoMP-enhanced network, which allows us to quantify the influence of key network parameters on the achievable network ESE, including the BS density and the cooperation activation probability, characterized by a CoMP activation factor as well as the users’ behaviors, such as their geographical mobile-traffic intensity and average user rate. With the aid of this tractable ESE expression and for a given BS density, we next formulate a cellular-scenario-aware CoMP activation optimization problem while considering the users’ outage probability as constraints to maximize the network’s ESE. We then jointly optimize the CoMP activation factor and the BS density to maximize the network ESE, again under the constraint of the users’ outage probability. Our simulation results confirm the accuracy of our analysis and verify the impact of several key parameters on the network ESE. Finally, the ESE improvement of our proposed strategies is evaluated under diverse scenarios, which provides valuable insight into the joint CoMP and BS deployment optimization in dense large-scale cellular networks. Autors: Guogang Zhao;Sheng Chen;Liqiang Zhao;Lajos Hanzo; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4832 - 4847 Publisher: IEEE
» Joint Estimation of Time, Frequency Offsets, and Channel Gains With ICIs in EF Multi-relay DMIMO-OFDM System
 Abstract:The cooperative communication or distributed multiple-input multiple-output (DMIMO) system, combined with orthogonal frequency division multiplexing (OFDM), is considered as an emerging paradigm for link reliability, high data rate, and coverage extension in fifth-generation (5G) wireless communication systems. The DMIMO system employs multiple relays with single or multiple antennas that opportunistically form virtual antenna array (VAA) in between the source and destination. Moving to the DMIMO-OFDM system from the conventional network with uncoordinated nodes requires robust synchronization and tracking. The signal received at the destination is characterized by multiple timing offsets (MTOs), multiple carrier frequency offsets (MCFOs), and frequency-selective channel gains. In this paper, we address the issue of joint time frequency and channel gain estimation for the estimate-and-forward (EF) relaying protocol. EF is a cost-effective solution but provides coarse estimation at the relays introducing intercarrier interferences (ICIs). OFDM system is very sensitive to the ICIs. We propose two iterative estimators: expectation conditional maximization (ECM) and space-alternating generalized expectation maximization (SAGE) to jointly estimate MTOs, MCFOs, and channel gains in the presence of ICIs. The robustness of the estimators is analyzed through mathematical formulation and simulations. The performances of the estimators are measured in terms of mean square error (MSE) and bit error rate (BER). The MSE performance is further verified with the theoretical Cramer–Rao lower bound (CRLB) derived. Simulation results show that the proposed estimators provide a significant performance gain in the DMIMO-OFDM system with MIMO configuration at the relays compared to the single-input single-output (SISO) system. Autors: Sucharita Chakraborty;Debarati Sen; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5822 - 5838 Publisher: IEEE
» Joint Hyperspectral Superresolution and Unmixing With Interactive Feedback
 Abstract:This paper presents an interactive feedback scheme of spatial resolution enhancement and spectral unmixing in hyperspectral imaging. Traditionally spatial resolution enhancement and spectral unmixing operations have been carried out separately, often in series. In such sequential processing, spatially enhanced hyperspectral images (HSIs) may introduce distortion in spectral fidelity making spectral unmixing results unreliable, or vice versa. Since both high- and low-resolution HSIs have the same endmembers, the deviation in spectral unmixing between targets and estimated high-resolution HSIs can be used as feedback to control spatial resolution enhancement. The spatial difference before and after unmixing can also be used as feedback to enhance spectral unmixing. Therefore, spectral unmixing is utilized as a constraint to spatial resolution enhancement, while spatial resolution enhancement helps improve spectral unmixing results. The performance of spatial resolution enhancement and spectral unmixing can be improved since one behaves like a prior to the other. Experimental results on both simulated and real HSI data sets demonstrate that the proposed interactive feedback scheme simultaneously achieved spatial resolution enhancement and spectral unmixing fidelity. This paper is an extended version of the previous work. Autors: Chen Yi;Yong-Qiang Zhao;Jingxiang Yang;Jonathan Cheung-Wai Chan;Seong G. Kong; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Jul 2017, volume: 55, issue:7, pages: 3823 - 3834 Publisher: IEEE
» Joint Intermodal and Intramodal Label Transfers for Extremely Rare or Unseen Classes
 Abstract:In this paper, we present a label transfer model from texts to images for image classification tasks. The problem of image classification is often much more challenging than text classification. On one hand, labeled text data is more widely available than the labeled images for classification tasks. On the other hand, text data tends to have natural semantic interpretability, and they are often more directly related to class labels. On the contrary, the image features are not directly related to concepts inherent in class labels. One of our goals in this paper is to develop a model for revealing the functional relationships between text and image features as to directly transfer intermodal and intramodal labels to annotate the images. This is implemented by learning a transfer function as a bridge to propagate the labels between two multimodal spaces. However, the intermodal label transfers could be undermined by blindly transferring the labels of noisy texts to annotate images. To mitigate this problem, we present an intramodal label transfer process, which complements the intermodal label transfer by transferring the image labels instead when relevant text is absent from the source corpus. In addition, we generalize the inter-modal label transfer to zero-shot learning scenario where there are only text examples available to label unseen classes of images without any positive image examples. We evaluate our algorithm on an image classification task and show the effectiveness with respect to the other compared algorithms. Autors: Guo-Jun Qi;Wei Liu;Charu Aggarwal;Thomas Huang; Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence Publication date: Jul 2017, volume: 39, issue:7, pages: 1360 - 1373 Publisher: IEEE
 Abstract:The 3GPP has proposed enhanced intercell interference coordination (eICIC) by making the macrocell silent in the almost blank subframes (ABSs) to mitigate interference for low-power base stations (BSs) in the downlink direction. However, two important challenges are introduced: 1) the underutilization for macrocell in ABS and 2) the optimal downlink association may not be optimal for uplink transmission, i.e., downlink/uplink decoupling (DUDe). In this paper, we first propose a novel method based on configuring uplink transmission in the macrocell in ABSs (UM-ABS) for eICIC to improve the efficiency of the ABS. Then, the UM-ABS and DUDe are formulated as an optimization problem of investigating the joint load balancing of downlink and uplink for eICIC in heterogeneous networks (HetNets) while considering different service classes. The problem is actually a mixed binary integer programming problem, which is difficult to solve. We provide a relaxed-rounding solution to the model. Numerical results illustrate that the proposed algorithm achieves superior performance in comparison to state-of-the-art methods in terms of system throughput and the rate gain for users. Autors: Jie Zheng;Jiandong Li;Nannan Wang;Xiaoniu Yang; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6388 - 6398 Publisher: IEEE
» Joint Millimeter Wave and Microwave Resources Allocation in Cellular Networks With Dual-Mode Base Stations
 Abstract:The use of dual-mode base stations that can jointly exploit millimeter wave (mmW) and microwave () resources is a promising solution for overcoming the uncertainty of the mmW environment. In this paper, a novel dual-mode scheduling framework is proposed that jointly performs user applications (UAs) selection and scheduling over and mmW bands. The proposed scheduling framework allows multiple UAs to run simultaneously on each user equipment (UE) and utilizes a set of context information, including the channel state information per UE, the delay tolerance and required load per UA, and the uncertainty of mmW channels, to maximize the quality-of-service (QoS) per UA. The dual-mode scheduling problem is then formulated as an optimization problem with minimum unsatisfied relations problem, which is shown to be challenging to solve. Consequently, a long-term scheduling framework, consisting of two stages, is proposed. Within this framework, first, the joint UA selection and scheduling over the band is formulated as a one-to-many matching game between the resources and UAs. To solve this problem, a novel scheduling algorithm is proposed and shown to yield a two-sided stable resource allocation. Second, over the mmW band, the joint context-aware UA selection and scheduling problem is formulated as a 0-1 Knapsack problem and a novel algorithm that builds on the Q-learning algorithm is proposed to find a suitable mmW scheduling policy while adaptively learning the UEs’ line-of-sight probabilities. Furthermore, it is shown that the proposed scheduling framework can find an effective schedu- ing solution, over both and mmW, in polynomial time. Simulation results show that, compared with conventional scheduling schemes, the proposed approach significantly increases the number of satisfied UAs while improving the statistics of QoS violations and enhancing the overall users’ quality-of-experience. Autors: Omid Semiari;Walid Saad;Mehdi Bennis; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4802 - 4816 Publisher: IEEE
» Joint Power and Rate Control for Packet Coding Over Fading Channels
 Abstract:We consider random linear packet coding for fading channels with long propagation delays, such as underwater acoustic channels. We propose a scheme in which the number of coded packets to transmit is determined to achieve a prespecified outage/reliability criterion and investigate joint power and rate control with constrained resources. Using the channel state information that is obtained via feedback from the receiver, the transmitter adjusts its power and the number of coded packets so that the average energy per successfully transmitted bit of information is minimized. Two optimization constraints are imposed: 1) the transmit power should not exceed a maximum level; and 2) the number of coded packets should not exceed a maximum value dictated by the desired throughput and delay. We further extend the results to take into account the effect of inevitable channel estimation errors, and consider the case in which the transmitter has only an estimate of the channel gain. We design adaptation policies for such a case based on minimum mean square error (MMSE) channel estimation, taking into account the effect of channel estimation errors in an optimal manner to satisfy the required outage/reliability criterion. Finally, we compare the proposed technique to standard automatic repeat request (ARQ) protocols for underwater communications in terms of the throughput efficiency. Analytical results show that substantial energy savings and improvements in throughput efficiency are available from adaptive power/rate control. We also present experimental results obtained using channel gains measured during the Surface Process Acoustic Communication Experiment (SPACE-08), an at-sea underwater experiment conducted off the coast of Martha's Vineyard in fall 2008. Autors: Rameez Ahmed;Milica Stojanovic; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Jul 2017, volume: 42, issue:3, pages: 697 - 710 Publisher: IEEE
» Joint Rate Control and Scheduling for Real-Time Wireless Networks
 Abstract:This paper studies wireless networks with multiple real-time flows that have stringent requirements on both per-packet delay and long-term average delivery ratio. Each flow dynamically adjusts its traffic load based on its observation of network status. When the requirements of per-packet delay and delivery ratio are satisfied, each flow obtains some utility based on its traffic load. We aim to design joint rate control and scheduling policies that maximize the total utility in the system. We first show that the problem of maximizing total utility can be formulated as a submodular optimization problem with exponentially many constraints. We then propose two simple distributed policies that require almost no coordination between different entities in the network. The total utilities under these two policies can be made arbitrarily close to the theoretical upper-bound. Extensive simulations also show that they achieve much better performance than state-of-the-art policies. Autors: Shuai Zuo;I-Hong Hou;Tie Liu;Ananthram Swami;Prithwish Basu; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4562 - 4570 Publisher: IEEE
» Joint Source and Relay Secure Beamforming for Nonregenerative MIMO Relay Systems With Wireless Information and Power Transfer
 Abstract:Simultaneous wireless information and power transfer (SWIPT) is able to prolong the lifetime of energy-constrained wireless networks. In this paper, we study the security issue of a nonregenerative multiple-input multiple-out (MIMO) relay system with SWIPT. When the full channel state information (CSI) of the eavesdropper is available, we aim to maximize the secrecy rate under the source and relay transmit power constraints and energy-harvesting (EH) constraints at the multiple EH receivers by jointly designing the source and relay beamforming matrices, which is a nonconvex optimization and is still an open problem. In order to enhance the secrecy rate effectively, we first transform the optimization into a difference of convex programming and propose a sequential parametric convex approximation-based iterative algorithm which is able to achieve a local optimum. To reduce the complexity, we also propose a singular value decomposition (SVD)-generalized SVD-based method to simplify the optimization into a joint source and relay power allocation problem. The alternating optimization is employed to find a suboptimal solution of the joint power allocation problem. When the CSI of the eavesdropper is unknown, we propose an artificial-noise (AN) aided joint source and relay beamforming scheme, which can maximize the AN power to jam the eavesdropper under the limited source and relay transmit power and satisfy the quality of service of the receiver. Simulation results have shown the effectiveness of our proposed schemes. Autors: Quanzhong Li;Jiayin Qin; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5853 - 5865 Publisher: IEEE
» Joint Source–Channel Coding for Broadcasting Correlated Sources
 Abstract:This paper studies lossy transmission of a memoryless bivariate Gaussian source over a bandwidth-mismatched memoryless Gaussian broadcast channel with two receivers, where each receiver is interested in reconstructing only one source component. For both bandwidth expansion and compression regimes, novel hybrid digital/analog (HDA) coding schemes are proposed. With appropriate choice of parameters, our schemes are shown to specialize to separate source–channel coding studied by Gao and Tuncel, and is, therefore, superior to it in both bandwidth regimes. Our scheme for bandwidth expansion also outperforms the HDA coding scheme of Behroozi et al. On the other hand, if a proposed conjecture (supported by numerical observations) is indeed true, the same superiority follows for the bandwidth compression regime as well. Finally, when the bandwidth expansion/compression ratio approaches 1, both of our schemes become optimal as their performance approaches that of the bandwidth-matched scheme of Tian et al. Autors: Erman Köken;Ertem Tuncel; Appeared in: IEEE Transactions on Communications Publication date: Jul 2017, volume: 65, issue:7, pages: 3012 - 3022 Publisher: IEEE
» Joint Source-Relay Secure Precoding for MIMO Relay Networks With Direct Links
 Abstract:In this paper, we propose a joint source-relay precoding scheme to secure an amplify-and-forward multiple-input multiple-output wireless relay network in the existence of a multi-antenna eavesdropper. Different from existing works that only consider some specific signal design to simplify the problem, we take both the direct links from the source to the destination and to the eavesdropper into account, and investigate the general joint signal covariance matrices optimization problem to maximize the secrecy rate, which leads to a difficult non-convex optimization problem. To handle it, we propose a group alternating optimization algorithm to find a solution, which alternately optimizes the signal covariance matrix and the linear precoding matrix at the source and the relay, respectively. For optimizing the linear precoding matrix at the relay, the problem is still non-convex, and we propose a minorization–maximization (MM) method to handle it. The MM method transforms the original non-convex problem into a series of convex problems and guarantees the convergence of a local optimum. For optimizing the signal covariance matrix at the source, we reveal the convex–concave property of the problem, and find its global optimum using a barrier method combined with the Newton iteration. We also provide an initialization method to trigger the algorithm and analyze the convergence and complexity. The numerical results show the computational efficiency and the prominent performance of the proposed algorithm. Autors: Hui-Ming Wang;Ke-Wen Huang;Qian Yang;Zhu Han; Appeared in: IEEE Transactions on Communications Publication date: Jul 2017, volume: 65, issue:7, pages: 2781 - 2793 Publisher: IEEE
» Kenneth Kwai-Hsiang Mei
 Abstract:Recounts the career and contributions of Kenneth Kwai-Hsiang Mei. Autors: George Oltman;Magdalena Salazar Palma; Appeared in: IEEE Microwave Magazine Publication date: Jul 2017, volume: 18, issue:5, pages: 124 - 124 Publisher: IEEE
» Kernel-Function-Based Models for Acoustic Localization of Underwater Vehicles
 Abstract:This paper proposes a novel design for the localization system of autonomous underwater vehicles (AUVs) using acoustic signals. The solution presented exploits models based on kernel functions with two main purposes: 1) to reject outliers; and 2) to correct or improve accuracy of measurements. The localization system discussed is based on well-established techniques such as support vector data description (SVDD) and autoassociative kernel regression (AAKR) derived from machine learning theory that utilizes heuristic models for classification and regression tasks, respectively. By coupling the algorithm to the navigation system, we seek to reduce the sensitivity of the localization scheme to the reflected acoustic waves or fluctuations of underwater channel properties without modifying the solution used for data fusion or overloading the algorithm embedded in the vehicle. Data collected in the field with a light underwater vehicle (LAUV) were used to demonstrate the advantages of the proposed approach. Autors: Breno C. Pinheiro;Ubirajara F. Moreno;João T. B. de Sousa;Orlando C. Rodríguez; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Jul 2017, volume: 42, issue:3, pages: 603 - 618 Publisher: IEEE
» Keyword Search for Building Service-Based Systems
 Abstract:With the fast growth of applications of service-oriented architecture (SOA) in software engineering, there has been a rapid increase in demand for building service-based systems (SBSs) by composing existing Web services. Finding appropriate component services to compose is a key step in the SBS engineering process. Existing approaches require that system engineers have detailed knowledge of SOA techniques which is often too demanding. To address this issue, we propose Keyword Search for Service-based Systems (KS3), a novel approach that integrates and automates the system planning, service discovery and service selection operations for building SBSs based on keyword search. KS3 assists system engineers without detailed knowledge of SOA techniques in searching for component services to build SBSs by typing a few keywords that represent the tasks of the SBSs with quality constraints and optimisation goals for system quality, e.g., reliability, throughput and cost. KS3 offers a new paradigm for SBS engineering that can significantly save the time and effort during the system engineering process. We conducted large-scale experiments using two real-world Web service datasets to demonstrate the practicality, effectiveness and efficiency of KS3. Autors: Qiang He;Rui Zhou;Xuyun Zhang;Yanchun Wang;Dayong Ye;Feifei Chen;John C. Grundy;Yun Yang; Appeared in: IEEE Transactions on Software Engineering Publication date: Jul 2017, volume: 43, issue:7, pages: 658 - 674 Publisher: IEEE
» Known-Artist Live Song Identification Using Audio Hashprints
 Abstract:The goal of live song identification is to allow concertgoers to identify a live performance by recording a few seconds of the performance on their cell phone. This paper proposes a multistep approach to address this problem for popular bands. In the first step, GPS data are used to associate the audio query with a concert in order to infer who the musical artist is. This reduces the search space to a dataset containing the artist's studio recordings. In the next step, the known-artist search is solved by representing the audio as a sequence of binary codes called hashprints, which can be efficiently matched against the database using a two-stage cross-correlation approach. The hashprint representation is derived from a set of spectrotemporal filters that are learned in an unsupervised artist-specific manner. On the Gracenote live song identification benchmark, the proposed system outperforms five other baseline systems and improves the mean reciprocal rank of the previous state of the art from 0.68 to 0.79, while simultaneously reducing the average runtime per query from 10 to 0.9 s. We conduct extensive analyses of major factors affecting system performance. Autors: TJ Tsai;Thomas Prätzlich;Meinard Müller; Appeared in: IEEE Transactions on Multimedia Publication date: Jul 2017, volume: 19, issue:7, pages: 1569 - 1582 Publisher: IEEE
» L-Band RFI Detected by SMOS and Aquarius
 Abstract:Ocean salinity and soil moisture are key parameters for understanding the global water cycle, weather, and climate. These parameters are being measured with spaceborne radiometers operating in the L-band window at 1400–1427 MHz. Although man-made activity in this band is prohibited, radio frequency interference (RFI) is still a problem over significant portions of the earth. This paper reports a comparison of the RFI environment in this window as observed by two L-band radiometer systems, Aquarius and Soil Moisture and Ocean Salinity. The observed RFI environment depends on the sources and also on the characteristics of the instrument. Comparing the observations provides insight into the extent of the problem (actual sources), the influence of the instrument on the observation of RFI, and on potential ways of mitigating the effects. As this report shows, the global distribution of RFI is largely consistent between the two instruments, but the details, especially at low levels of RFI, depend on the characteristics of the instrument. Autors: Yan Soldo;David M. Le Vine;Paolo de Matthaeis;Philippe Richaume; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Jul 2017, volume: 55, issue:7, pages: 4220 - 4235 Publisher: IEEE
» Lanthanum and Lanthanum Silicide Contacts on N-Type Silicon
 Abstract:In this letter, we investigate contacts of a low work function rare-earth metal, La, and its silicides on n-Si. LaSix/-Si contacts show low Schottky barrier height () of around 0.25–0.4 eV and promisingly low contact resistivity () on moderately doped -Si. However, on highly doped -Si, we find of LaSix near one order higher than the TiSix control. This experiment indicates that low does not guarantee low on highly doped substrates. We further discuss reasons behind this phenomenon. Autors: Hao Yu;Lin-Lin Wang;Marc Schaekers;Jean-Luc Everaert;Yu-Long Jiang;Dan Mocuta;Naoto Horiguchi;Nadine Collaert;Kristin De Meyer; Appeared in: IEEE Electron Device Letters Publication date: Jul 2017, volume: 38, issue:7, pages: 843 - 846 Publisher: IEEE
» Large Area Self-Powered Al-ZnO/(n)Si Hetero-Junction Photodetectors With High Responsivity
 Abstract:Al-ZnO/Si heterojunction-based large area, self-powered, low reverse leakage current, and broadband photodetectors with high responsivity are fabricated using the simple and low temperature process. Different from widely applied (p)Si-based heterojunctions, these devices are (n)Si-based and offer superior performance. With optimized Al–ZnO thickness, excellent light confinement is achieved. An interfacial passivation layer that improves the hetero-interface helps achieved a reverse current density as low as A/cm at −0.5 V for a 4.84 cm2 device, with rectification ratio of at ±0.5 V. In self-powered mode, the photodetector achieved responsivities of 0.292, 0.426, and 0.486 A/W (external quantum efficiency, EQE of 78.7%, 96.1%, and 98.8%) for primary blue (460 nm), green (550 nm), and red (610 nm) light, respectively. The operation of self-powered Al–ZnO/(n)Si photodetectors is demonstrated for the first time with modulated optical signal at circuit level. Autors: Zhen Gao;Navid M. S. Jahed;Siva Sivoththaman; Appeared in: IEEE Photonics Technology Letters Publication date: Jul 2017, volume: 29, issue:14, pages: 1171 - 1174 Publisher: IEEE
» Large-Scale Nonlinear Lumped and Integrated Field Simulations of Top-Orthogonal-to-Bottom-Electrode CMUT Architectures
 Abstract:Capacitive micromachined ultrasonic transducers (CMUTs) promise many advantages over traditional piezoelectric transducers such as the potential to construct large, cost-effective 2-D arrays. To avoid wiring congestion issues associated with fully wired arrays, top-orthogonal-to-bottom electrode (TOBE) CMUT array architectures have proven to be a more practical alternative, using only wires for an array. Optimally designing a TOBE CMUT array is a significant challenge due to the range of parameters from the device level up to the operating conditions of the entire array. Since testing many design variations can be prohibitively expensive, a simulation approach accounting for both the small and large-scale array characteristics of TOBE arrays is essential. In this paper, we demonstrate large-scale TOBE CMUT array simulations using a nonlinear CMUT lumped-circuit model. We investigate the performance of the array with different CMUT design parameters and array operating conditions. These simulated results are then compared with measurements of TOBE arrays fabricated using a sacrificial release process. Autors: Chris Ceroici;Roger J. Zemp; Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control Publication date: Jul 2017, volume: 64, issue:7, pages: 1087 - 1091 Publisher: IEEE
» Large-Scale Parallel Method of Moments on CPU/MIC Heterogeneous Clusters
 Abstract:A hybrid message passing interface and open multiprocessing (OpenMP) enabled many integrated core (MIC) coprocessor-accelerated implementation of the large-scale parallel method of moments (MoM) for solving electromagnetic problems is presented. The out-of-MIC memory strategy and asynchronous data transfer scheme are employed to address the problems of accelerating MoM on CPU/MIC computing platform, and a parallel framework is designed to achieve large-scale parallel algorithm on CPU/MIC clusters. The experimental results show that a high parallel efficiency of 45% is achieved when 1024 computing nodes or 80 000 cores are utilized. Autors: Yan Chen;Sheng Zuo;Yu Zhang;Xunwang Zhao;Huanhuan Zhang; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Jul 2017, volume: 65, issue:7, pages: 3782 - 3787 Publisher: IEEE
 Abstract:We propose a novel network architecture by leveraging the cloudlet concept, the software defined networking technology, and the cellular network infrastructure to bring the computing resource to the mobile edge. In order to minimize the average response time for mobile users (MUs) in offloading their application workloads to the geographically distributed cloudlets, we propose the latency-aware workload offloading (LEAD) strategy to allocate MUs’ application workloads into suitable cloudlets. Simulation results demonstrate that LEAD incurs the lowest average response time as compared with two other existing strategies. Autors: Xiang Sun;Nirwan Ansari; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1481 - 1484 Publisher: IEEE
» Latency-Limited Broadcast Channel With Cache-Equipped Helpers
 Abstract:Decreasing communication latency is one of the main challenges for many applications in future communication systems. As a solution, we study in this work the benefits of using some cache-equipped helpers in a wireless communication scenario. More precisely, a wireless network with a transmitter, two cache-equipped helpers, and two receivers is studied from the latency point of view. While the transmitter has access to the whole data, the helpers store some data in their cache in order to support the transmitter in fulfilling the demands of the receivers. The main challenge is to develop a joint caching placement and the transmission strategy, which minimizes the latency of the communication. To this end, a general encoded caching is considered, in which each message is split into four types of sub-messages. The sub-messages of the first and second types are stored only in the cache of the first and second helper, respectively. The sub-messages of the third type are cached at both helpers, while the sub-messages of the fourth type are not cached at any helper. The size of the sub-messages is optimized in a way such that the delivery time of one bit for the worst-case demand is minimized. Moreover, a general lower bound on the delivery time is provided. Using this lower bound as a benchmark, the performance of the proposed caching policy is evaluated. It is shown that facilitating the cache-equipped helpers decreases the latency of broadcasting. Furthermore, it is shown that for the proposed caching policy, storing identical sub-messages in the cache of different helpers cannot be optimal if the cache size of the helpers is insufficiently large. Autors: Soheil Gherekhloo;Aydin Sezgin; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4192 - 4203 Publisher: IEEE
» Latent Regression Forest: Structured Estimation of 3D Hand Poses
 Abstract:In this paper we present the latent regression forest (LRF), a novel framework for real-time, 3D hand pose estimation from a single depth image. Prior discriminative methods often fall into two categories: holistic and patch-based. Holistic methods are efficient but less flexible due to their nearest neighbour nature. Patch-based methods can generalise to unseen samples by consider local appearance only. However, they are complex because each pixel need to be classified or regressed during testing. In contrast to these two baselines, our method can be considered as a structured coarse-to-fine search, starting from the centre of mass of a point cloud until locating all the skeletal joints. The searching process is guided by a learnt latent tree model which reflects the hierarchical topology of the hand. Our main contributions can be summarised as follows: (i) Learning the topology of the hand in an unsupervised, data-driven manner. (ii) A new forest-based, discriminative framework for structured search in images, as well as an error regression step to avoid error accumulation. (iii) A new multi-view hand pose dataset containing 180 K annotated images from 10 different subjects. Our experiments on two datasets show that the LRF outperforms baselines and prior arts in both accuracy and efficiency. Autors: Danhang Tang;Hyung Jin Chang;Alykhan Tejani;Tae-Kyun Kim; Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence Publication date: Jul 2017, volume: 39, issue:7, pages: 1374 - 1387 Publisher: IEEE
» Lazy Irrevocability for Best-Effort Transactional Memory Systems
 Abstract:IBM and Intel now offer commercial systems with Transactional Memory (TM), a programming paradigm whose aim is to facilitate concurrent programming while maximizing parallelism. These TM systems are implemented in hardware and provide a software fallback path to overcome the hardware implementation limitations. They are known as best-effort hardware TM (BE-HTM) systems. The software fallback path must be provided by the user to ensure forward progress, which adds programming complexity to the TM paradigm. We propose a new type of irrevocability (a transactional mode that marks transactions as non-abortable) to deal with BE-HTM limitations in a more efficient manner, and to liberate the user from having to program a fallback path. It is based on the concept of lazy subscription used in the context of software fallback paths, where the fallback lock is checked at the end of the transaction instead of at the beginning. We propose a hardware lazy irrevocability mechanism that does not involve changes in the coherence protocol. It solves the unsafe execution problem of premature commits associated with lazy subscription fallbacks, and can be triggered by the user via an ISA extension, for the sake of versatility. It is compared with its software counterpart, which we propose as an enhanced lazy single global lock with escaped spinning at the end of the transaction. We also propose the lazy irrevocability with anticipation, a mechanism that cannot be implemented in software, which significantly improves the performance of codes with multiple cache evictions of transactional data. The evaluation of the proposals is carried out with the Simics/GEMS simulator along with the STAMP benchmark suite, and we obtain speedups from 14 to 28 percent over the fallback path approaches. Autors: Ricardo Quislant;Eladio Gutierrez;Emilio L. Zapata;Oscar Plata; Appeared in: IEEE Transactions on Parallel and Distributed Systems Publication date: Jul 2017, volume: 28, issue:7, pages: 1919 - 1932 Publisher: IEEE
» LCD Cyclic Codes Over Finite Fields
 Abstract:In addition to their applications in data storage, communications systems, and consumer electronics, linear complementary dual (LCD) codes—a class of linear codes—have been employed in cryptography recently. LCD cyclic codes were referred to as reversible cyclic codes in the literature. The objective of this paper is to construct several families of reversible cyclic codes over finite fields and analyze their parameters. The LCD cyclic codes presented in this paper have very good parameters in general, and contain many optimal codes. A well rounded treatment of reversible cyclic codes is also given in this paper. Autors: Chengju Li;Cunsheng Ding;Shuxing Li; Appeared in: IEEE Transactions on Information Theory Publication date: Jul 2017, volume: 63, issue:7, pages: 4344 - 4356 Publisher: IEEE
» LDPC Codes Based on the Space of Symmetric Matrices Over Finite Fields
 Abstract:In this paper, we present a new method for explicitly constructing regular low-density parity-check (LDPC) codes based on , the space of symmetric matrices over . Using this method, we obtain two classes of binary LDPC codes, and , both of which have grith 8. Then, both the minimum distance and the stopping distance of each class are investigated. It is shown that the minimum distance and the stopping distance of are both . As for , we determine the minimum distance and the stopping distance for some special cases and obtain some lower bounds for other cases. Autors: Changli Ma;Qi Wang;Meng Zhao; Appeared in: IEEE Transactions on Information Theory Publication date: Jul 2017, volume: 63, issue:7, pages: 4332 - 4343 Publisher: IEEE
» Lead-Free Multilayer Piezoceramic Composites: Effect of Cosintering on Electromechanical Properties
 Abstract:The macroscopic electromechanical behavior of lead-free multilayer composites was characterized from room temperature to 150 °C. The polar seed component consisted of a nonergodic relaxor (Bi1/2Na1/2)TiO3-7BaTiO3, with an electric-field-induced long-range ferroelectric order, whereas the nonpolar matrix was an ergodic relaxor Bi0.5(Na0.75K0.25)0.5 TiO3-6BiAlO3 that undergoes a reversible electric-field-induced macroscopic nonpolar-to-polar transition. Microstructural evidence of the effects of cosintering are demonstrated through examination of grain size, interdiffusion, and pore structure. By manipulating the sintering interactions between the two constituents, namely, diffusion paths and residual stresses, both internal mechanical and electrical fields, as well as compositional gradients can be used to enhance the unipolar strain over that expected by a rule of mixtures approximation, thereby improving the properties needed for application of such materials to actuator systems. Autors: Azatuhi Ayrikyan;Andreas Kastner;Neamul Hayet Khansur;Shintaro Yasui;Mitsuru Itoh;Kyle G. Webber; Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control Publication date: Jul 2017, volume: 64, issue:7, pages: 1127 - 1134 Publisher: IEEE
» Leader Set Selection for Low-Latency Geo-Replicated State Machine
» Learning to Segment Human by Watching YouTube
 Abstract:An intuition on human segmentation is that when a human is moving in a video, the video-context (e.g., appearance and motion clues) may potentially infer reasonable mask information for the whole human body. Inspired by this, based on popular deep convolutional neural networks (CNN), we explore a very-weakly supervised learning framework for human segmentation task, where only an imperfect human detector is available along with massive weakly-labeled YouTube videos. In our solution, the video-context guided human mask inference and CNN based segmentation network learning iterate to mutually enhance each other until no further improvement gains. In the first step, each video is decomposed into supervoxels by the unsupervised video segmentation. The superpixels within the supervoxels are then classified as human or non-human by graph optimization with unary energies from the imperfect human detection results and the predicted confidence maps by the CNN trained in the previous iteration. In the second step, the video-context derived human masks are used as direct labels to train CNN. Extensive experiments on the challenging PASCAL VOC 2012 semantic segmentation benchmark demonstrate that the proposed framework has already achieved superior results than all previous weakly-supervised methods with object class or bounding box annotations. In addition, by augmenting with the annotated masks from PASCAL VOC 2012, our method reaches a new state-of-the-art performance on the human segmentation task. Autors: Xiaodan Liang;Yunchao Wei;Liang Lin;Yunpeng Chen;Xiaohui Shen;Jianchao Yang;Shuicheng Yan; Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence Publication date: Jul 2017, volume: 39, issue:7, pages: 1462 - 1468 Publisher: IEEE
» Leveling Up: Using E-waste to Build a Gaming Console
 Abstract:Our world is facing an alarming problem of e-waste, which has a deep impact on humanity and our environment. According to the Global E-Waste Management Market, from 2014 to 2016, the rate of producing e-waste exceeded 93.5 million tons annually. There are currently var ious techniques for handling e-waste such as recycling, reducing consumption, and reusing containers, which are helpful but have their limits, as these efforts eventually require the use of landfills, which is not optimal for the environment. Autors: Afaq Ahmad; Appeared in: IEEE Potentials Publication date: Jul 2017, volume: 36, issue:4, pages: 36 - 38 Publisher: IEEE
» Life Assessment of Electric Arc Furnace Transformers
 Abstract:Electric arc furnace transformers are very important in the steel production industry. Currently, it is very common for companies to buy used transformers considering the huge investment that represents the acquisition of a new transformer and also the delay in the purchase transaction. Before accepting a commercial agreement and putting the transformer into operation, it is necessary to evaluate the level of wear out due to the electrical and magnetic stresses to which the transformer is subjected. Electrical, mechanical, and insulation tests, that follow procedures stipulated in guides and standards, are performed on used transformers during the purchase process in order to identify incipient faults and to determine their general condition. A methodology is proposed to carry out these tests. In addition, a new model based on fuzzy logic is implemented to assess the level of wear of the transformer, its remaining life, and its feasibility of reuse. The fuzzy input variables of this new model are the results of the tests performed on each element of the transformer. Autors: Eduardo A. Cano-Plata;Oscar J. Soto-Marin;Armando J. Ustariz-Farfan; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 4125 - 4135 Publisher: IEEE
» Lightweight Virtual Memory Support for Zero-Copy Sharing of Pointer-Rich Data Structures in Heterogeneous Embedded SoCs
 Abstract:While high-end heterogeneous systems are increasingly supporting heterogeneous uniform memory access (hUMA), their low-power counterparts still lack basic features like virtual memory support for accelerators. Instead of simply passing pointers, explicit data management involving copies is needed which hampers programmability and performance. In this work, we evaluate a mixed hardware/software solution for lightweight virtual memory support for many-core accelerators in heterogeneous embedded systems-on-chip. Based on an input/output translation lookaside buffer managed by a host kernel-level driver, and compiler extensions protecting the accelerator’s accesses to shared data, our solution is non-intrusive to the architecture of the accelerator cores, and enables zero-copy sharing of pointer-rich data structures. Autors: Pirmin Vogel;Andrea Marongiu;Luca Benini; Appeared in: IEEE Transactions on Parallel and Distributed Systems Publication date: Jul 2017, volume: 28, issue:7, pages: 1947 - 1959 Publisher: IEEE
» Linear Minimum Mean Square Filters for Markov Jump Linear Systems
 Abstract:This paper studies optimal mean square error estimation for discrete-time linear systems with observed Markov jump parameters. New linear estimators are introduced by considering a cluster information structure in the filter design. The set of filters constructed in this way can be ordered in a lattice according to the refines of clusters of the Markov chain, including the linear Markovian estimator at one end (with only one cluster) and the Kalman filter at the other end (with as many clusters as Markov states). The higher is the number of clusters, the heavier are precomputations and smaller is the estimation error for embedded sequences of partitions so that the cardinality and choice of the clusters allows for a tradeoff between performance and computational requirements. In this paper, we propose the estimator, give the formulas for precomputation of gains, present some properties, and give an illustrative numerical example. Autors: Eduardo F. Costa;Benoîte de Saporta; Appeared in: IEEE Transactions on Automatic Control Publication date: Jul 2017, volume: 62, issue:7, pages: 3567 - 3572 Publisher: IEEE
» Linear Precoder Design for SWIPT in MIMO Broadcasting Systems With Discrete Input Signals: Manifold Optimization Approach
 Abstract:In this paper, we investigate the design of linear precoders for simultaneously wireless information and power transfer (SWIPT) in a multi-input multi-output (MIMO) broadcasting system with discrete input signals. The considered system model consists of one base station (BS), one information receiver (IR), and one energy receiver (ER). The design objective is to maximize the input–output mutual information of the IR subject to the power constraint and the harvested energy requirement for the ER. We derive the structure of the optimal linear precoder by using manifold optimization, and propose an algorithm to find the optimal precoder. Simulation results show that the proposed algorithm can achieve better performance than the time sharing scheme and the Gaussian optimal precoder when Gaussian inputs are replaced by discrete input signals. Autors: An-An Lu;Xiqi Gao;Yahong Rosa Zheng;Chengshan Xiao; Appeared in: IEEE Transactions on Communications Publication date: Jul 2017, volume: 65, issue:7, pages: 2877 - 2888 Publisher: IEEE
» Linear Soft Combination for Cooperative Spectrum Sensing in Cognitive Radio Networks
 Abstract:In this letter, we study the cooperative energy-based combination for spectrum sensing in cognitive radio networks. Linear combination rule is investigated to minimize the probability of missed detection subject to an upper limit on the probability of false alarm. We propose a novel and practical linear combination rule, which only requires the mean and variance of the local test statistics. The performance of the proposed combination rule is verified in three typical fading scenarios: the slow fading, the block fading, and the fast fading. Simulations show that the proposed strategy has nearly the same performance as the optimal likelihood-ratio test approaches, and outperforms the conventional linear combination methods. Autors: Huayan Guo;Wei Jiang;Wu Luo; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1573 - 1576 Publisher: IEEE
» Link-Layer Cooperation Based on Distributed TDMA MAC for Vehicular Networks
 Abstract:Cooperative medium access control (MAC) protocols have been proposed for improving communication reliability and throughput in wireless networks. In our previous work, a cooperative MAC scheme called Cooperative ADHOC MAC (CAH-MAC) has been proposed to increase the network throughput under a static networking scenario for vehicular communications. In this paper, we study the effects of relative mobility among nodes and channel fading on the performance of CAH-MAC. In a dynamic networking environment, system performance degrades due to cooperation collisions. To tackle this challenge, we present an enhanced CAH-MAC (eCAH-MAC) scheme, which avoids cooperation collisions and efficiently utilizes cooperation opportunities without disrupting the time-slot reservation operations. Through mathematical analysis and computer simulations, we show that eCAH-MAC increases the effectiveness of node cooperation by increasing utilization of an unreserved time slot. Furthermore, we perform extensive simulations for realistic networking scenarios to investigate the probability of successful cooperative relay transmission and usage of unreserved time slots in eCAH-MAC, in comparison with existing approaches. Autors: Sailesh Bharati;Weihua Zhuang;Lakshmi V. Thanayankizil;Fan Bai; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6415 - 6427 Publisher: IEEE
» Load Disaggregation Based on Aided Linear Integer Programming
 Abstract:Load disaggregation based on aided linear integer programming (ALIP) is proposed. We start with a conventional linear integer programming (IP)-based disaggregation and enhance it in several ways. The enhancements include additional constraints, correction based on a state diagram, median filtering, and linear-programming-based refinement. With the aid of these enhancements, the performance of IP-based disaggregation is significantly improved. The proposed ALIP system relies only on the instantaneous load samples instead of waveform signatures and, hence, works well on low-frequency data. Experimental results show that the proposed ALIP system performs better than conventional IP-based load disaggregation. Autors: Md. Zulfiquar Ali Bhotto;Stephen Makonin;Ivan V. Bajić; Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs Publication date: Jul 2017, volume: 64, issue:7, pages: 792 - 796 Publisher: IEEE
» Load Following of Multiple Heterogeneous TCL Aggregators by Centralized Control
 Abstract:Aggregate thermostatically controlled loads (TCLs) are good candidates for providing load following services in power systems. This paper is concerned with the modeling, evaluation, and control problems of a population of heterogeneous TCLs. Specifically, the heterogeneous population is divided into multiple homogeneous clusters and each cluster, i.e., TCL aggregator, is modeled by an approximated three-input single-output state space model. Here, the aggregators serve as a bridge connecting the load utility and the terminal TCLs, which have their own decision makers and are responsible for aggregate estimation and command issuing. And aggregate evaluation is carried out for the aggregator so as to provide the aggregate regulation capacities and ramping rates, which is useful for setting of the reference power trajectory. Based on the established control model, we furthermore propose a hierarchical centralized control algorithm for a bus load utility to regulate all TCLs inside it so as to provide load following service, while not affecting the customers’ comfort levels. Finally, simulation results with respect to a common bus load are provided to demonstrate the effectiveness of the proposed aggregate modeling and the centralized load following strategy. Autors: Jianqiang Hu;Jinde Cao;Michael Z. Q. Chen;Jie Yu;Jianguo Yao;Shengchun Yang;Taiyou Yong; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3157 - 3167 Publisher: IEEE
» Load Signature Generator for Appliance State Sensing and Energy Disaggregation
 Abstract:Appliance state sensing is a load monitoring method that requires the ON/OFF states and global consumption measurements of appliances in order to achieve energy disaggregation. Previously proposed sensor networks employed uncalibrated, overrated, and costly wireless modules to collect appliance states. In contrast, we present a simple communication scheme, in which data are transmitted through the powerline to a main meter. For this purpose, we designed a smart sensor, the circuitry of which operates as a load signature generator. It generates fixed-amplitude and short-duration rectangular current pulses that encode information about the status of an appliance. For evaluation, we tested four sensors in a small electrical model and performed a numerical simulation using raw current waveforms contained in the reference energy disaggregation data set. The performance of the applied signal processing algorithms shows a symbol error rate of less than 1% when pulse position modulation with amplitudes of 2 A or more is used. Autors: Guillermo Sovero;Nicolás C. Kemper;Ernst Kussul; Appeared in: IEEE Sensors Journal Publication date: Jul 2017, volume: 17, issue:14, pages: 4587 - 4594 Publisher: IEEE
» Load-Balanced Opportunistic Routing for Duty-Cycled Wireless Sensor Networks
 Abstract:In duty-cycled wireless sensor networks running asynchronous MAC protocols, the time when a sender waits for its receiver to wake up and receive the packet is the major source of energy consumption. Opportunistic routing can reduce the sender wait time by allowing multiple candidate receivers, but by doing that it suffers from redundant packet forwarding due to multiple receivers waking up at the same time. Thus, the number of forwarders should be controlled in a way that overall forwarding cost is minimized considering both sender wait time and cost of redundant packet forwarding. Also, in order to prolong network lifetime, candidate forwarders should be selected so that load is balanced among nodes. We propose ORR, an opportunistic routing protocol that addresses the two issues. First, the optimal number of forwarders is calculated based on forwarding cost estimation, which is derived from duty cycle and network topology. Second, the metric used for selecting forwarders considers residual energy so that more traffic is guided through nodes with larger remaining energy. The resulting routing protocol is proven to avoid loops and shown to achieve longer network lifetime compared to other protocols regardless of duty cycle and network topology. Autors: Jungmin So;Heejung Byun; Appeared in: IEEE Transactions on Mobile Computing Publication date: Jul 2017, volume: 16, issue:7, pages: 1940 - 1955 Publisher: IEEE
» Local and Remote Estimations Using Fitted Polynomials in Distribution Systems
 Abstract:This work describes a technique to define a single parametric equation that estimates remote conditions within a distribution network, in an online setting, without dedicated telemetry. In this novel approach, a departure from conventional state estimation is explored to facilitate a fully decentralized operation. Derived based on fundamental treatment of ac power flow, the electrical behavior of a section of network is defined to a tractable constraint space using regression analysis. In this noniterative technique, a measurement set consisting of the local voltage magnitude, active and reactive power injections at a single node are the input to precomputed polynomials. Remote current flow, active power and reactive power flow, as well as remote and local voltages and sensitivities are estimated in a direct calculation from period to period. Accurate estimations are also found in the presence of transducer errors. To assess the applicability of this technique at differing voltage levels, a range of reactance to resistance ratios are considered. Autors: Conor Murphy;Andrew Keane; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3185 - 3194 Publisher: IEEE
» Local Suppression and Splitting Techniques for Privacy Preserving Publication of Trajectories
 Abstract:We study the problem of preserving user privacy in the publication of location sequences. Consider a database of trajectories, corresponding to movements of people, captured by their transactions when they use credit cards, RFID debit cards, or NFC (http://en.wikipedia.org/wiki/Near_field_communication) compliant devices. We show that, if such trajectories are published exactly (by only hiding the identities of persons that followed them), one can use partial trajectory knowledge as a quasi-identifier for the remaining locations in the sequence. We devise four intuitive techniques, based on combinations of locations suppression and trajectories splitting, and we show that they can prevent privacy breaches while keeping published data accurate for aggregate query answering and frequent subsets data mining. Autors: Manolis Terrovitis;Giorgos Poulis;Nikos Mamoulis;Spiros Skiadopoulos; Appeared in: IEEE Transactions on Knowledge and Data Engineering Publication date: Jul 2017, volume: 29, issue:7, pages: 1466 - 1479 Publisher: IEEE
» Local Transverse-Slice-Based Level-Set Method for Segmentation of 3-D High-Frequency Ultrasonic Backscatter From Dissected Human Lymph Nodes
 Abstract:Objective: To detect metastases in freshly excised human lymph nodes (LNs) using three-dimensional (3-D), high-frequency, quantitative ultrasound (QUS) methods, the LN parenchyma (LNP) must be segmented to preclude QUS analysis of data in regions outside the LNP and to compensate ultrasound attenuation effects due to overlying layers of LNP and residual perinodal fat (PNF). Methods: After restoring the saturated radio-frequency signals from PNF using an approach based on smoothing cubic splines, the three regions, i.e., LNP, PNF, and normal saline (NS), in the LN envelope data are segmented using a new, automatic, 3-D, three-phase, statistical transverse-slice-based level-set (STS-LS) method that amends Lankton's method. Due to ultrasound attenuation and focusing effects, the speckle statistics of the envelope data vary with imaged depth. Thus, to mitigate depth-related inhomogeneity effects, the STS-LS method employs gamma probability-density functions to locally model the speckle statistics within consecutive transverse slices. Results: Accurate results were obtained on simulated data. On a representative dataset of 54 LNs acquired from colorectal-cancer patients, the Dice similarity coefficient for LNP, PNF, and NS were 0.938 0.025, 0.832 0.086, and 0.968 0.008, respectively, when compared to expert manual segmentation. Conclusion: The STS-LS outperforms the established methods based on global and local statistics in our datasets and is capable of accurately handling the depth-dependent effects due to attenuation and focusing. Significance: This advance permits the automatic QUS-based cancer detection in the LNs. Furthermore, the- STS-LS method could potentially be used in a wide range of ultrasound-imaging applications suffering from depth-dependent effects. Autors: Thanh Minh Bui;Alain Coron;Jonathan Mamou;Emi Saegusa-Beecroft;Tadashi Yamaguchi;Eugene Yanagihara;Junji Machi;S. Lori Bridal;Ernest Joseph Feleppa; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Jul 2017, volume: 64, issue:7, pages: 1579 - 1591 Publisher: IEEE
» Location Based Handshake and Private Proximity Test with Location Tags
 Abstract:A location proximity test service allows mobile users to determine whether they are in close proximity to each other, and has found numerous applications in mobile social networks. Unfortunately, existing solutions usually reveal much of users’ private location information during a proximity test. They are also vulnerable to location cheating where an attacker reports false locations to gain an advantage. Moreover, the initial trust establishment among unfamiliar users in large scale mobile social networks has been a challenging task. In this paper, we propose a novel scheme that enables a user to perform (1) a location based handshake that establishes secure communications among strangers, who do not have a pre-shared secret, and (2) a privacy-preserving proximity test without revealing the user’s actual location to the server or other users not within the proximity. The proposed scheme is based on a novel concept, i.e., spatial-temporal location tags, and we put forward a location tag construction method using environmental signals that provides an unforgeable location proof. We use Bloom filters to efficiently represent users’ location tags and vicinity regions. We exploit fuzzy extractor, a lightweight cryptographic primitive, to extract shared secrets between matching location tags. We conduct extensive analysis, simulation, and real experiments to demonstrate the feasibility, security, and efficiency of our scheme. Autors: Yao Zheng;Ming Li;Wenjing Lou;Y. Thomas Hou; Appeared in: IEEE Transactions on Dependable and Secure Computing Publication date: Jul 2017, volume: 14, issue:4, pages: 406 - 419 Publisher: IEEE
» Log-Sum Distance Measures and Its Application to Human-Activity Monitoring and Recognition Using Data From Motion Sensors
 Abstract:For the detection of human activities using motion data many techniques employ feature extraction and machine learning. But detection rates and incorrect classification rates require further increase and decrease, respectively. We address both the problems. We propose a novel distance measure, called log-sum distance, for evaluating difference between two sequences of positive numbers. We use the proposed log-sum distance measure to develop algorithms for recognition of human activities from the motion data. The sequences of positive numbers are residual sum of squares errors produced from modeling motion time-series with the multiple linear regression method. To reduce incorrect classification, we define a threshold test and use it in our proposed novel algorithm. We have defined an optimization function and used it for computing optimal threshold values. Extensive evaluation of our activity detection algorithm with two different sets of data sets show increased activity recognition rates and decreased incorrect classification rates compared with other existing methods. In one data set, the proposed algorithm detects all activities with 100% accuracy and in the another data set, it detects all activities with 99% or higher accuracy. The proposed use of threshold values for classification of activities decreased incorrect classification rates. Autors: Faisal Sikder;Dilip Sarkar; Appeared in: IEEE Sensors Journal Publication date: Jul 2017, volume: 17, issue:14, pages: 4520 - 4533 Publisher: IEEE
» Logic Circuits With Hydrogenated Diamond Field-Effect Transistors
 Abstract:As a first step to develop a diamond integrated circuit, hydrogenated diamond not and nor logic circuits composed of depletion-mode (D-mode) and enhancement-mode (E-mode) metal–oxide–semiconductor field-effect transistors (MOSFETs) are fabricated. The D- and E-modes MOSFETs act as load and driver devices for the logic circuits, respectively, which provides complementary transistor actions. The extrinsic transconductance maxima for both the MOSFETs are almost the same value of 17 mS mm and insensitive to device processing. With supply voltage changing from −5 to −25 V, gain maximum for not logic circuit increases from 1.2 to 26.1. The nor logic circuit shows clear nor gate characteristics. Autors: Jiangwei Liu;Hirotaka Ohsato;Meiyong Liao;Masataka Imura;Eiichiro Watanabe;Yasuo Koide; Appeared in: IEEE Electron Device Letters Publication date: Jul 2017, volume: 38, issue:7, pages: 922 - 925 Publisher: IEEE
 Abstract:In this paper, we propose a novel greedy algorithm referred to as look-ahead hybrid matching pursuit (LAHMP) for multipolarization through-wall radar imaging (TWRI). From the viewpoint of compressive sensing, the task of multipolarization TWRI can be formulated as a problem of sparsity pattern recovery under the joint sparsity model. A newly developed greedy algorithm for joint sparsity model, hybrid matching pursuit (HMP), combines the strengths of orthogonal matching pursuit and subspace pursuit and improves the accuracy of the sparsity pattern recovery. Besides, the look-ahead strategy can select an optimal atom by evaluating its effectiveness on the overall reconstruction quality. Through integrating the virtues of HMP with the look-ahead strategy, the proposed LAHMP aims to more accurately select atoms corresponding to the true targets behind walls. Experiments based on measured radar data show that, compared to existing greedy algorithms, LAHMP provides better image quality at affordable expense of computational complexity. Autors: Xueqian Wang;Gang Li;Qun Wan;Robert J. Burkholder; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Jul 2017, volume: 55, issue:7, pages: 4072 - 4081 Publisher: IEEE
» Low Complexity Interference Alignment for mmWave MIMO Channels in Three-Cell Mobile Network
 Abstract:Millimeter wave (mmWave) communications are an important candidate technique in 5G networks for features, supporting ultra-dense small cells and mobile data offloading. However, ultra-dense nodes and increasing data traffic bring in vast interference. This paper investigates low complexity non-iterative interference alignment (IA) schemes for multiple-input multiple-output (MIMO) interference broadcast channels in mmWave communications. The authors focus on the three-cell mobile network model in which each base station supports no more than two users within its cell. There is already a closed-form IA solution for the case that one cell has two users, while the other two have one user in each, which can be denoted as {2,1,1}. This paper considers different settings and proposes corresponding IA schemes. First, two IA schemes based on multi-step for the asymmetric setting {2,2,1} are presented, five degree of freedom (DoF) could be achieved. Then, for the symmetric setting {2,2,2}, a novel IA solution with lower complexity and a joint method combining IA with non-iterative multi-user MIMO technique are proposed, and they can achieve six DoF. The simulation results indicate that our non-iterative schemes have similar sum-rate capacity performances with the iterative ones in existing work, and the complexity is effectively reduced. Autors: Chaowei Wang;Cai Qin;Yuan Yao;Yong Li;Weidong Wang; Appeared in: IEEE Journal on Selected Areas in Communications Publication date: Jul 2017, volume: 35, issue:7, pages: 1513 - 1523 Publisher: IEEE
» Low Complexity ZF and MMSE Detectors for the Uplink MU-MIMO Systems With a Time-Varying Number of Active Users
 Abstract:The classical multiuser detection algorithms such as zero forcing (ZF) and minimum mean square error (MMSE) receivers are designed with the assumption that the number of active users is constant and known. When the number of the active users changes, the receiver may exhibit a serious performance loss if it does not react quickly to such variations. In this paper, we address the problem of reducing the complexity of the reevaluation of the popular ZF and MMSE detectors for multiuser multiple-input multiple-output (MU-MIMO) systems with a time-varying number of users in the channel. For each technique, we propose a detection approach with low complexity and without performance loss. The proposed algorithms avoid the direct computation of matrix inverses required by the ZF and MMSE detectors. Moreover, the performance losses, due to the use of the ZF and MMSE detectors intended for the scenario with a fixed number of active users, are evaluated with Monte Carlo simulation results. Autors: Mohamed Lassaad Ammari;Paul Fortier; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6586 - 6590 Publisher: IEEE
» Low Read Latency Rewriting Codes for Multi-Level 3-D NAND Flash
 Abstract:Rewriting codes can improve the lifetime capacity of NAND flash. All existing -ary rewriting codes for NAND flash assume that the exact cell levels are known to decoders, and thus the number of reads needed is , while the current NAND technology enables low latency page reads by dividing a physical page into logical pages, so that the average number of reads per page is . We consider 2-write rewriting codes that enable low latency page reads for multi-level NAND flash memories. We design a low read latency rewriting code that enables 17% capacity improvement and maintains 1.5 reads per page for four-level multiple-level cells. We also design codes for eight-level triple level cells that enable 11% and 24% capacity improvement with 2 and 2.5 reads per page, respectively. The same Gray codes in current NAND technology that map binary data to physical cell levels are applied to avoid redesigning hardware and circuits inside the chip. Autors: Minghai Qin;Robert Mateescu;Chao Sun;Zvonimir Bandic; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1477 - 1480 Publisher: IEEE
» Low-Complexity MIMO Precoding for Finite-Alphabet Signals
 Abstract:This paper investigates the design of precoders for single-user multiple-input multiple-output (MIMO) channels, and, in particular, for finite-alphabet signals. Based on an asymptotic expression for the mutual information of channels exhibiting line-of-sight components and rather general antenna correlations, precoding structures that decompose the general channel into a set of parallel subchannel pairs are proposed. Then, a low-complexity iterative algorithm is devised to maximize the sum mutual information of all pairs. The proposed algorithm significantly reduces the computational load of existing approaches with only minimal loss in performance. The complexity savings increase with the number of transmit antennas and with the cardinality of the signal alphabet, making it possible to support values thereof that were unmanageable with existing solutions. Most importantly, the proposed solution does not require instantaneous channel state information (CSI) at the transmitter, but only statistical CSI. Autors: Yongpeng Wu;Derrick Wing Kwan Ng;Chao-Kai Wen;Robert Schober;Angel Lozano; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4571 - 4584 Publisher: IEEE
» Low-Complexity QoS-Aware Coordinated Scheduling for Heterogeneous Networks
 Abstract:In this paper, we consider a heterogenous network in which low-power indoor femtocells are deployed in the coverage area of the existing macrobase station (MBS). This paper proposes a novel coordinated random beamforming and user-scheduling strategy to improve the throughput of users served by the femtocell access point (FAP) while satisfying the quality-of-service (QoS) requirements of users served by both MBS and FAP. The strategy, termed as QoS-aware coordinated scheduling (QACS), requires limited coordination between the MBS and FAP, i.e., only the indexes of the qualified beams are shared. Exact statistical analysis for the ergodic achievable rate of both FAP and MBS with the proposed strategy are presented. Scheduling fairness is also addressed for the proposed QACS. Autors: Jun Zhu;Hong-Chuan Yang; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6596 - 6601 Publisher: IEEE
» Low-Cost X/Ku/Ka-Band Dual-Polarized Array With Shared Aperture
 Abstract:This paper presents a novel tri-band (X/Ku/Ka-band) planar antenna array with dual polarizations and shared aperture. Compared with traditional dual-polarized arrays, the proposed array has advantages of low cost, low profile, and high integration. Three types of antennas resonating at different frequencies, including the perforated patch, stacked patch, and slim crosspatch, are innovatively interleaved in the same aperture. The crosspatch fed by proximity coupling is presented as Ku-band element for its advantages of compact size, high isolation, and pure polarization. The techniques such as series feed and reverse feed are utilized to implement the six feed networks in a compact size with reduced cross polarizations. Measured results agree well with the simulations, showing three operation bands at X-, Ku-, and Ka-bands with the bandwidths of 3.6%, 6.7%, and 5.3%, respectively. The antenna also exhibits excellent radiation performance with the cross-polarization discrimination over 25 dB at the three bands. To the best of the author’s knowledge, this is the first shared-aperture X/Ku/Ka-band dual-polarized antenna array reported, which is useful for potential synthetic aperture radar applications. Autors: Chun-Xu Mao;Steven Gao;Qi Luo;Tobias Rommel;Qing-Xin Chu; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Jul 2017, volume: 65, issue:7, pages: 3520 - 3527 Publisher: IEEE
» Low-Drift Optoelectronic Oscillator Based on a Phase Modulator in a Sagnac Loop
 Abstract:A low-drift optoelectronic oscillator (OEO) is developed and experimentally shown. In the proposed OEO, a fiber Sagnac interferometer, including an optical phase modulator (PM) and a nonreciprocal bias unit, functions as an intrinsically drift-free intensity modulator. The phase noise of the proposed OEO is modeled in phase space, which is verified by experiments. Phase noise and frequency stability of the photonically generated microwave signals are measured. The single-sideband phase noise of the generated microwave signal is −106.6 dBc/Hz at 10-kHz offset from the 10.833-GHz carrier, with 120-fs rms timing jitter integrated from 1 kHz to 10 MHz. Frequency drift measurements show ±0.85-ppm maximum fractional frequency deviation over 35 h, mainly caused by drift of the fiber delay line. Autors: S. Esmail Hosseini;Ali Banai;Franz X. Kärtner; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Jul 2017, volume: 65, issue:7, pages: 2617 - 2624 Publisher: IEEE
» Low-Frequency Impedance Monitoring and Corresponding Failure Criteria for Aluminum Electrolytic Capacitors
 Abstract:Condition monitoring of aluminum electrolytic capacitors (AECs) is essential for predictive maintenance of power electronic converters. The AEC is considered at the end of its life when its capacitance or equivalent series resistance (ESR) reaches corresponding critical values. In the literature, it is found that either of these parameters may reach its critical limit depending on the operating conditions and applications. However, most of the existing health monitoring techniques of the AEC in dc–dc converters are based on the estimation of ESR. To address the aforementioned issue, this paper proposes to estimate the low-frequency impedance of the AEC, which is dominated by its capacitance value, thereby allowing health monitoring based on the capacitance value. The technique is based on injection of a low-frequency current ripple into the AEC using duty ratio control of the dc–dc converter. The parameters of new and aged capacitors are experimentally obtained at various temperatures and are used to establish the failure criteria. Furthermore, the proposed method is applicable for both the continuous conduction mode and the discontinuous conduction mode (DCM) of operation. For DCM operation, a sampling instant to recover a low-frequency waveform is suggested based on mathematical analysis. Detailed simulation studies are performed and results are included in this paper. Experimentation is carried out on a dc–dc boost converter integrating solar photovoltaic with the dc system. Experimental results are found to be in agreement with simulation results. Autors: Md. Waseem Ahmad;Nikunj Agarwal;P. Nandha Kumar;Sandeep Anand; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Jul 2017, volume: 64, issue:7, pages: 5657 - 5666 Publisher: IEEE
» Low-Power Wideband Analog Channelization Filter Bank Using Passive Polyphase-FFT Techniques
 Abstract:Polyphase-FFT (P-FFT) techniques allow for low power implementations of high performance multi-channel filter banks by utilizing computation sharing like a standard fast Fourier transform (FFT). Additionally, it enables a longer “effective window length” than is possible in a standard FFT. This characteristic breaks the trade-off between the main-lobe width and the side-lobe amplitudes in normal finite impulse response filters. Thus, P-FFT techniques have been employed for the channelization of wideband input signals in high speed digital communication receivers. In this paper, we present a prototype analog P-FFT based filter bank in discrete time that is used to channelize wideband input signals so as to reduce the speed and dynamic range requirement of the ADCs. The four-channel I/Q prototype is implemented using TSMC’s 65 nm GP technology. Based on passive switches, the design operates at high speed, consumes low power, and offers high linearity performance. The measured transfer function shows >38 dB side-lobe suppression at 1 GS/s operation. The average measured IIP3 is +25 dBm differential power and the total integrated output noise is 208 . The total power consumption for the P-FFT filter bank (eight-channels total) is 34.6 mW (34.6 pJ/conv). Autors: Hundo Shin;Ramesh Harjani; Appeared in: IEEE Journal of Solid-State Circuits Publication date: Jul 2017, volume: 52, issue:7, pages: 1753 - 1767 Publisher: IEEE
» Low-Rank Tensor Decomposition-Aided Channel Estimation for Millimeter Wave MIMO-OFDM Systems
 Abstract:We consider the problem of downlink channel estimation for millimeter wave (mmWave) MIMO-OFDM systems, where both the base station (BS) and the mobile station (MS) employ large antenna arrays for directional precoding/beamforming. Hybrid analog and digital beamforming structures are employed in order to offer a compromise between hardware complexity and system performance. Different from most existing studies that are concerned with narrowband channels, we consider estimation of wideband mmWave channels with frequency selectivity, which is more appropriate for mmWave MIMO-OFDM systems. By exploiting the sparse scattering nature of mmWave channels, we propose a CANDECOMP/PARAFAC (CP) decomposition-based method for channel parameter estimation (including angles of arrival/departure, time delays, and fading coefficients). In our proposed method, the received signal at the MS is expressed as a third-order tensor. We show that the tensor has the form of a low-rank CP, and the channel parameters can be estimated from the associated factor matrices. Our analysis reveals that the uniqueness of the CP decomposition can be guaranteed even when the size of the tensor is small. Hence the proposed method has the potential to achieve substantial training overhead reduction. We also develop Cramér-Rao bound (CRB) results for channel parameters and compare our proposed method with a compressed sensing-based method. Simulation results show that the proposed method attains mean square errors that are very close to their associated CRBs and present a clear advantage over the compressed sensing-based method. Autors: Zhou Zhou;Jun Fang;Linxiao Yang;Hongbin Li;Zhi Chen;Rick S. Blum; Appeared in: IEEE Journal on Selected Areas in Communications Publication date: Jul 2017, volume: 35, issue:7, pages: 1524 - 1538 Publisher: IEEE
» Low-Voltage Unipolar Inverter Based on Top-Gate Electric-Double-Layer Thin-Film Transistors Gated by Silica Proton Conductor
 Abstract:In this letter, low-voltage unipolar inverter based on solid-state silica electric-double-layer (EDL) top-gate thin-film transistors was fabricated. A silicon oxide film deposited by the plasma-enhanced chemical vapor deposition method at room temperature was used as inorganic electrolyte insulator. Due to the formation of the EDL, the inverter can work at low voltages that are less than 1 V. The voltage transfer curves and the dynamic switching behaviors at different switching frequencies were investigated. The inverters can be integrated with low-voltage applications, such as biosensors, portable electronics, and synaptic devices, which work at low operation voltages and relatively low speeds. Autors: Jiabin Wang;Yuxing Li;Yi Yang;Tian-Ling Ren; Appeared in: IEEE Electron Device Letters Publication date: Jul 2017, volume: 38, issue:7, pages: 875 - 878 Publisher: IEEE
» Lower Bounds on the Oracle Complexity of Nonsmooth Convex Optimization via Information Theory
 Abstract:We present an information-theoretic approach to lower bound the oracle complexity of nonsmooth black box convex optimization, unifying previous lower bounding techniques by identifying a combinatorial problem, namely string guessing, as a single source of hardness. As a measure of complexity, we use distributional oracle complexity, which subsumes randomized oracle complexity as well as worst case oracle complexity. We obtain strong lower bounds on distributional oracle complexity for the box , as well as for the -ball for (for both low-scale and large-scale regimes), matching worst case upper bounds, and hence we close the gap between distributional complexity, and in particular, randomized complexity and worst case complexity. Furthermore, the bounds remain essentially the same for high-probability and bounded-error oracle complexity, and even for combination of the two, i.e., bounded-error high-probability oracle complexity. This considerably extends the applicability of known bounds. Autors: Gábor Braun;Cristóbal Guzmán;Sebastian Pokutta; Appeared in: IEEE Transactions on Information Theory Publication date: Jul 2017, volume: 63, issue:7, pages: 4709 - 4724 Publisher: IEEE
» LP Relaxation of the Potts Labeling Problem Is as Hard as Any Linear Program
 Abstract:In our recent work, we showed that solving the LP relaxation of the pairwise min-sum labeling problem (also known as MAP inference in graphical models or discrete energy minimization) is not much easier than solving any linear program. Precisely, the general linear program reduces in linear time (assuming the Turing model of computation) to the LP relaxation of the min-sum labeling problem. The reduction is possible, though in quadratic time, even to the min-sum labeling problem with planar structure. Here we prove similar results for the pairwise min-sum labeling problem with attractive Potts interactions (also known as the uniform metric labeling problem). Autors: Daniel Průša;Tomáš Werner; Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence Publication date: Jul 2017, volume: 39, issue:7, pages: 1469 - 1475 Publisher: IEEE
» LTS-Based Robust Hybrid SE Integrating Correlation
 Abstract:The paper introduces a robust approach for hybrid power system static state estimation (SE) utilizing phasor measurement units (PMUs). The proposed PMU-based SE exploits the time and space correlation in the PMU measurements in order to provide rejection of bad measurements and improve the SE cyber security and accuracy. The SE robustness is introduced in two steps. The first step is to robustly fit multichannel or vector autoregressive models to adjacent PMUs. The second step replaces the classical weighted least squares algorithm with a robust regression estimator. The robustness is introduced by exploiting the least trimmed squares estimator. The effectiveness of the proposed robust PMU-based SE is assessed based on Monte Carlo simulations and compared with other existing robust SE methods. A theoretical analysis is provided to explain the improvement by higher PMU sampling rates and longer periods of SE. Autors: Yacine Chakhchoukh;Vijay Vittal;Gerald T. Heydt;Hideaki Ishii; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3127 - 3135 Publisher: IEEE
» Lyapunov Functions for Persistently-Excited Cascaded Time-Varying Systems: Application to Consensus
 Abstract:We present some results on stability of linear time-varying systems with particular structures. Such systems appear in diverse problems, which include the analysis of adaptive systems, persistently-excited observers and consensus of systems interconnected through time-varying links. The originality of our statements rely in the fact that we provide smooth strict Lyapunov functions hence, our proofs are constructive and direct. Moreover, we establish uniform global exponential stability with explicit stability and decay estimates. For illustration, we address a brief but representative case-study of consensus of Lagrangian systems interconnected through unreliable links. Autors: Mohamed Maghenem;Antonio Loría; Appeared in: IEEE Transactions on Automatic Control Publication date: Jul 2017, volume: 62, issue:7, pages: 3416 - 3422 Publisher: IEEE
» MA-SSR: A Memetic Algorithm for Skyline Scenic Routes Planning Leveraging Heterogeneous User-Generated Digital Footprints
 Abstract:Most existing trip planning work ignores the issue of planning detailed travel routes between points of interest, leaving the task to online map services or commercial Global Poisioning System (GPS) navigators. However, such a service or navigator cannot meet the diverse requirements of users. Particularity, in this paper, we aim at planning travel routes that not only minimize the distance but provide high-quality sceneries along the way as well. To this end, we propose a novel two-phase framework to plan travel routes efficiently in a large road network considering multiple criteria, i.e., both the quality of the scenic view and the travel distance. In the first phase, we enrich the edges and assign a proper scenic view score for each of them by extracting relevant information from heterogeneous digital footprints of geotagged images and check-ins. In the second phase, on the top of the enriched road network, given users’ trip queries, we employ the concept of skyline operator and propose a memetic algorithm (MA) to discover a set of equally optimal routes with diverse travel distances for users to pick from. Finally, to validate the efficiency and effectiveness of the proposed framework, we conduct extensive experiments on three real-world datasets from the Bay Area in the city of San Francisco, CA, USA, which contain a road network with 3771 nodes and 5940 edges crawled from OpenStreetMap, more than 31 000 geotagged images generated by 1571 Flickr users in one year; and 110 214 check-ins left by 15 680 Foursquare users in six months. Results demonstrate that the MA yields high-quality solutions that are reasonably close to the optima but within desirable computation time and considerably better than the baseline solutions obtained by genetic algorithms. Autors: Chao Chen;Xia Chen;Leye Wang;Xiaojuan Ma;Zhu Wang;Kai Liu;Bin Guo;Zhen Zhou; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5723 - 5736 Publisher: IEEE
» Machine Learning Based Power Grid Outage Prediction in Response to Extreme Events
 Abstract:A machine learning based prediction method is proposed in this paper to determine the potential outage of power grid components in response to an imminent hurricane. The decision boundary, which partitions the components’ states into two sets of damaged and operational, is obtained via logistic regression by using a second-order function and proper parameter fitting. Two metrics are examined to validate the performance of the obtained decision boundary in efficiently predicting component outages. Autors: Rozhin Eskandarpour;Amin Khodaei; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3315 - 3316 Publisher: IEEE
» Magneto-Modulating Polarization Converter Based on a Dual-Core Photonic Crystal Fiber
 Abstract:A magneto-modulating polarization converter (PC) based on a new type dual-core photonic crystal fiber (DCPCF) is proposed and analyzed. In DCPCF, the two cores are surrounded by a central circular air hole and two lateral elliptical air holes in the horizontal axis. The central air hole is filled with magnetic fluids (MF). Without external magnetic field, DCPCF acts as a simple polarization splitter. When magnetic field applied, due to the refractive index of MF varying with the magnetic field magnitude, the intensities of the two polarization modes would interchange alternately. At a certain magnetic field, the two polarization modes would rotate 90° at the output ports. In this case, a magneto-modulating PC is realized. The performance of the PC is analyzed by the finite element method. The simulation results show that the length of the PC is 1007 μm. The polarization mode conversion can be realized at a magnetic field magnitude of 40.5 mT with a room temperature 21°C. A high extinction ratio greater than 70 dB is obtained for mode-conversion around 1550 nm wavelength. In addition, the PC works well in the temperature range from 0°C to 60°C by regulating the magnetic field magnitude. The optical fiber-based PC eliminates the silicon-on-insulator circuit chip, which can be integrated with optical system easily and conveniently. Autors: Jianshuai Wang;Li Pei;Sijun Weng;Liangying Wu;Lin Huang;Tigang Ning;Jing Li; Appeared in: Journal of Lightwave Technology Publication date: Jul 2017, volume: 35, issue:14, pages: 2772 - 2777 Publisher: IEEE
» Managing Wind Power Uncertainty Through Strategic Reserve Purchasing
 Abstract:With the rapidly increasing penetration of wind power, wind producers are becoming increasingly responsible for the deviation of the wind power output from the forecast. Such uncertainty results in revenue losses to the wind power producers (WPPs) due to penalties in ex-post imbalance settlements. This paper explores the opportunities available for WPPs if they can purchase or schedule some reserves to offset part of their deviation rather than being fully penalized in the real-time market. The revenue for WPPs under such mechanism is modeled. The optimal strategy for managing the uncertainty of wind power by purchasing reserves to maximize the WPP's revenue is analytically derived with rigorous optimality conditions. The amount of energy and reserves that should be bid in the market is explicitly quantified by the probabilistic forecast and the prices of the energy and reserves. A case study using the price data from ERCOT and wind power data from NREL is performed to verify the effectiveness of the derived optimal bidding strategy and the benefits of reserve purchasing. Additionally, the proposed bidding strategy can also reduce the risk of variations on WPP's revenue. Autors: Ershun Du;Ning Zhang;Chongqing Kang;Benjamin Kroposki;Han Huang;Miao Miao;Qing Xia; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 2547 - 2559 Publisher: IEEE
» Matched Multiuser Gaussian Source Channel Communications via Uncoded Schemes
 Abstract:We investigate whether uncoded schemes are optimal for Gaussian sources on multiuser Gaussian channels. Particularly, we consider two problems: the first is to send correlated Gaussian sources on a Gaussian broadcast channel where each receiver is interested in reconstructing only one source component (or one specific linear function of the sources) under the mean squared error distortion measure; the second is to send correlated Gaussian sources on a Gaussian multiple-access channel, where each transmitter observes a noisy combination of the sources, and the receiver wishes to reconstruct the individual source components (or individual linear functions) under the mean squared error distortion measure. It is shown that when the channel parameters satisfy certain general conditions, the induced distortion tuples are on the boundary of the achievable distortion region, and thus optimal. Instead of following the conventional approach of attempting to characterize the achievable distortion region, we ask the question whether and how a match can be effectively determined. This decision problem formulation helps to circumvent the difficult optimization problem often embedded in region characterization problems, and it also leads us to focus on the critical conditions in the outer bounds that make the inequalities become equalities, which effectively decouple the overall problem into several simpler sub-problems. Optimality results previously unknown in the literature are obtained using this novel approach. Explicit and novel outer bounds are derived for the two problems as the byproducts of our investigation. Autors: Chao Tian;Jun Chen;Suhas N. Diggavi;Shlomo Shamai Shitz; Appeared in: IEEE Transactions on Information Theory Publication date: Jul 2017, volume: 63, issue:7, pages: 4155 - 4171 Publisher: IEEE
» Maximizing Common Idle Time on Multicore Processors With Shared Memory
 Abstract:Nowadays, memory energy reduction attracts significant attention as main memory consumes large amount of energy among all the energy consuming components. This paper focuses on reducing the energy consumption of the shared main memory in multicore processors by putting the memory into sleep state when all cores are idle. Based on this idea, we present systematic analysis of different models and propose a series of scheduling schemes to maximize the common idle time of all cores. The target problem is classified into two cases based on whether task migration is allowed or not among cores. Considering task migration, an optimal scheduling scheme is proposed, assuming the number of cores is unbounded. When the number of cores is bounded, an integer linear programming formulation and two efficient heuristic algorithms are proposed. When task migration is not allowed, we first prove the NP-hardness of the problem, and then propose the optimal solutions when task partitions are given in advance. The energy overhead caused by transitions between active and sleep modes of the memory is analyzed. The experimental results show that the heuristic algorithms work efficiently and can save 7.25% and 11.71% system energy, respectively, with 1-GB memory, compared with an energy-efficient multicore scheduling scheme. Larger energy reduction can be further achieved with larger size of memory. Autors: Chenchen Fu;Yingchao Zhao;Minming Li;Chun Jason Xue; Appeared in: IEEE Transactions on Very Large Scale Integration Systems Publication date: Jul 2017, volume: 25, issue:7, pages: 2095 - 2108 Publisher: IEEE
» Maximum Efficiency Current Waveforms for a PMSM Including Iron Losses and Armature Reaction
 Abstract:Permanent magnet synchronous machines (PMSMs) are popular due to their high efficiency and favorable dynamic properties. In practice, these machines often have a back-electromotive force (EMF) waveform, which deviates from a theoretically ideal sinusoid or trapezoid. In the past, current waveform shaping techniques were developed for these machines to calculate nonconventional current waveforms to reduce the torque ripple. However, in the light of global warming, energy efficiency has become more important than torque ripple in many applications. Therefore, current waveform shaping techniques can be used to focus on maximum efficiency. In this paper, a technique is presented that maximizes the efficiency of both the PMSM and the drive simultaneously. A time domain approach is used instead of the classical frequency domain approach, which allows us to include many machine aspects that had to be neglected previously, i.e., armature reaction, reluctance, zero-sequence components, and iron losses. Autors: Jeroen D. M. De Kooning;Jan Van de Vyver;Bart Meersman;Lieven Vandevelde; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3336 - 3344 Publisher: IEEE
» Maximum Lifetime Combined Barrier-Coverage of Weak Static Sensors and Strong Mobile Sensors
 Abstract:Recently, the concept of barrier-coverage of wireless sensor network has been introduced for various civilian and military defense applications. This paper studies the problem of how to organize hybrid sensor network, which consists of a number of energy-scarce ground sensors with homogenous initial battery level and energy-plentiful mobile sensors, to maximum the lifetime of barrier-coverage. Two key observations are (a) as the lifetime of each mobile sensor is much longer than that of the static ground sensors, each mobile sensor is capable of contributing multiple sensor barrier formations, and (b) no mobile sensor node can join two hybrid barriers which will be successively used to continuously protect the area of interest due to the moving delay. Based on these, we introduce a new maximum lifetime barrier-coverage problem in hybrid sensor network. We first propose a simple heuristic algorithm by combining existing ideas along with our own. Then, we design another efficient algorithm for the problem and prove that the lifetime of hybrid barrier constructed by this algorithm is at least three times greater than the existing one on average. Our simulation result shows that the second algorithm outperforms the first algorithm at least 33 percent and up to 100 percent. Autors: Donghyun Kim;Wei Wang;Junggab Son;Weili Wu;Wonjun Lee;Alade O. Tokuta; Appeared in: IEEE Transactions on Mobile Computing Publication date: Jul 2017, volume: 16, issue:7, pages: 1956 - 1966 Publisher: IEEE
» Maximum Torque Per Ampere Control in Stator Flux Linkage Synchronous Frame for DTC-Based PMSM Drives Without Using q-Axis Inductance
 Abstract:When direct torque control (DTC) is applied to permanent-magnet synchronous motor (PMSM) drives, the relationship between the torque and stator flux linkage is important for high-efficiency drives because DTC requires them as references. In the stator flux linkage synchronous frame (M–T frame), the torque is described by a simple equation using the T-axis current. However, the M-axis current is neglected in the equation. This paper derives the relationship between the M-axis current and the stator flux linkage, and proposes a maximum torque per ampere (MTPA) control strategy for direct torque controlled PMSM drives using the above relationship. The proposed method does not require the q-axis inductance, which often varies due to the magnetic saturation. The simulation and experimental results verify that the MTPA condition can be obtained with the proposed method. Autors: Atsushi Shinohara;Yukinori Inoue;Shigeo Morimoto;Masayuki Sanada; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3663 - 3671 Publisher: IEEE
» Maximum Wind Energy Extraction for Variable Speed Wind Turbines With Slow Dynamic Behavior
 Abstract:Currently, the maximization of wind energy extraction for variable speed wind turbines (VSWT) is usually transformed into the maximum power point tracking (MPPT), i.e., the rotor speed is continuously regulated to follow the optimal rotor speed as a function of wind speed. However, it has been recognized that the increasing rotor inertia and the high fluctuation of wind speed result in the turbines’ being unable to instantly track the optimal rotor speed and tracking losses. This indicates that maximizing wind energy extraction based on MPPT is not suitable for large-inertia VSWTs under turbulence. Moreover, it is revealed and demonstrated in this letter that a conservative speed reference matching up with the slow dynamic behavior of VSWTs can effectively improve wind energy production, which provides a new approach for maximizing wind energy extraction of VSWTs under turbulence. Autors: Zaiyu Chen;Minghui Yin;Yun Zou;Ke Meng;ZhaoYang Dong; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3321 - 3322 Publisher: IEEE
» Measure for the Difference Between LBP Features Extracted From Original and Resized Cloud Images With Varying Resolutions
 Abstract:Currently, ground-based cloud images taken by using a whole-sky imager are especially popular in the field of meteorology because of their high resolution and accurate cloud information. Cloud images are natural texture images, and thus texture features based on local binary patterns (LBPs) are widely used to analyze texture images. However, the high-computation cost of extracting LBP features from high-resolution cloud texture images may make this technique unacceptable in practical image processing. A commonly adopted method is to resize the original image to an appropriate version with a decreased resolution. But this process will inevitably result in information loss. Accordingly, a measure based on the Kullback–Leibler (KL) divergence of the difference between LBP histogram features extracted from the original and resized images with varying resolutions is reported in this letter. Furthermore, a confidence interval technique is introduced to validate the significance of such difference. Experiments based on real ground-based cloud images show the measurement results of KL divergence in LBP features extracted from original and resized images. The experimental results indicate that images should be resized with caution when performing image processing. Autors: Yu Wang;Cunzhao Shi;Chunheng Wang;Baihua Xiao; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Jul 2017, volume: 14, issue:7, pages: 1106 - 1110 Publisher: IEEE
» Measurement and Analysis of Frequency-Domain Volterra Kernels of Nonlinear Dynamic $3 \times 3$ MIMO Systems
 Abstract:Multiple-input multiple-output (MIMO) frequency-domain Volterra kernels of nonlinear order 3 are experimentally determined in bandwidth-limited frequency regions. How the effect of higher nonlinear orders can be reduced and how this affects the estimated errors are discussed. The magnitude and the phase of the kernels are Kramers-Kronig consistent. The self-kernels and cross-kernels have different symmetries, and the kernels are therefore determined and analyzed in different regions in the 3-D frequency space. By analyzing the properties along certain paths in the 3-D frequency space, the block structures for the respective kernels are determined. These block structures contain the significant blocks of the general block structures for the third-order kernels. The device under test is an MIMO transmitter for radio frequency signals. Autors: Mahmoud Alizadeh;Shoaib Amin;Daniel Rönnow; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Jul 2017, volume: 66, issue:7, pages: 1893 - 1905 Publisher: IEEE
» Measurement Challenges for 5G and Beyond: An Update from the National Institute of Standards and Technology
 Abstract:The NIST CTL has launched several new programs to support advances in 5G mmW and multiple-antenna technology. The high levels of electronic device integration anticipated for 5G wireless technology yield a radically new connectorless measurement paradigm in which “on-wafer to OTA” measurements will be the norm. This increased reliance on OTA testing represents a large focus of NIST's work. Also, measurements, calibrations, and channel characterization in the mmW frequency bands must be corrected for the increasingly nonideal hardware found at mmW frequencies. Measurement science can play a significant role in addressing these technical challenges through new calibrations, models, and uncertainty analyses. Autors: Kate A. Remley;Joshua A. Gordon;David Novotny;Alexandra E. Curtin;Christopher L. Holloway;Matthew T. Simons;Robert D. Horansky;Michael S. Allman;Damir Senic;Maria Becker;Jeffrey A. Jargon;Paul D. Hale;Dylan F. Williams;Ari Feldman;Jerome Cheron;Richa Appeared in: IEEE Microwave Magazine Publication date: Jul 2017, volume: 18, issue:5, pages: 41 - 56 Publisher: IEEE
» Measurement of Magnetic Field and Temperature Based on Fiber-Optic Composite Interferometer
 Abstract:A novel, highly sensitive dual-parameter sensor based on a composite interference structure has been designed and implemented in this paper. The sensor was composed of a Fabry-Pérot interferometer, where the microcavity was filled by magnetic fluid (MF) and a Mach-Zehnder interferometer, where the photonic crystal fiber was filled with ethanol. The refractive index of the MF and ethanol would be changed with the increase of magnetic field and temperature. Hence, simultaneous measurement of temperature and refractive index can be achieved by monitoring the reflected spectrum and transmitted spectrum. The sensitivities of MF and ethanol can reach up to 0.033 nm/Gs and 0.236 nm/°C, respectively. Autors: Xue-Gang Li;Yong Zhao;Lu Cai;Xue Zhou; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Jul 2017, volume: 66, issue:7, pages: 1906 - 1911 Publisher: IEEE
» Memcomputing (Memristor + Computing) in Intrinsic SiOx-Based Resistive Switching Memory: Arithmetic Operations for Logic Applications
 Abstract:In this paper, implication (IMP) operations are demonstrated in a circuit with two SiOx-based memristors and a CMOS transistor. Specifically, a circuit with two one-diode and one-resistor (1D1R) memory elements and a transistor are designed to perform the IMP operations. A circuit consisting of a crossbar 1D1R memristor array together with selection transistors is proposed and used to realize the functionality of a one-bit, full adder in 43 steps. Compared with CMOS logic circuits, the advantages and disadvantages of memristor-enabled logic circuits are discussed. This result suggests that the memristor-enabled logic circuit is most suitable for low-power and high-density applications, as well as a simple and robust approach to realize programmable memcomputing chips compatible with large-scale CMOS manufacturing technology. Autors: Yao-Feng Chang;Fei Zhou;Burt W. Fowler;Ying-Chen Chen;Cheng-Chih Hsieh;Lauren Guckert;Earl E. Swartzlander;Jack C. Lee; Appeared in: IEEE Transactions on Electron Devices Publication date: Jul 2017, volume: 64, issue:7, pages: 2977 - 2983 Publisher: IEEE
» Memory-Optimized Re-Gridding Architecture for Non-Uniform Fast Fourier Transform
 Abstract:This paper proposes a power-efficient and memory-optimized FPGA-based solution for the memory and compute-intense re-gridding process used in implementing Non-uniform Fast Fourier Transform (NuFFT) algorithm. Re-gridding refers to mapping non-equispaced sampled data onto a uniform grid using an interpolation kernel function. Re-gridding is the most time-consuming step in the entire NuFFT computation. The proposed solution is based on better utilization of FPGA resources and minimizing the number of accesses to the external memory. We demonstrate high performance over a wide range of configurations and data-sizes. This paper targets a generic solution to arbitrary sampling trajectories and gives trajectory specific solutions for some well-known trajectories in NuFFT applications, such as magnetic resonance imaging and synthetic aperture radar. Compared with existing solutions, throughput is improved by over 9.6 when compared with the existing FPGA-based techniques, whereas computational power efficiency (in terms of MFLOPS/Watt) is improved by over 15 times. Compared with GPU-based technique, 9.59 times higher MFLOPS per watts are achieved. The proposed architecture is implemented using hardware description language as well as high-level synthesis (HLS)-based OpenCL framework and the comparison is reported. Hence, this paper also serves as a reference for the comparison of HLS-based solutions against optimized HDLs. Accuracy of the re-gridding process is also reported in terms of signal-to-noise ratio. Autors: Umer I. Cheema;Gregory Nash;Rashid Ansari;Ashfaq Khokhar; Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers Publication date: Jul 2017, volume: 64, issue:7, pages: 1853 - 1864 Publisher: IEEE
» Memristive Model for Synaptic Circuits
 Abstract:As a promising alternative for next-generation memory, memristors provide several useful features such as high density, nonvolatility, low power, and good scalability as compared with conventional CMOS-based memories. In this brief, a voltage-controlled threshold memristive model is proposed, which is based on experimental data of memristive devices. Moreover, the model is more suitable for the design of memristor-based synaptic circuits as compared with other memristive models. The effects of memristance variations are considered in the proposed model to evaluate the behavior of memristive synapses within memristor-based neural networks. Autors: Yang Zhang;Xiaoping Wang;Yi Li;Eby G. Friedman; Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs Publication date: Jul 2017, volume: 64, issue:7, pages: 767 - 771 Publisher: IEEE
» Message From the Incoming Editor-in-Chief
 Abstract: Autors: N. Kato; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5517 - 5517 Publisher: IEEE
» Metameric Indoor Localization Schemes Using Visible Lights
 Abstract:In indoor environments, visible light communications paradigm is emerging as a viable promising solution complementary to well-known radio frequency technology. At the same time, the information about user's location is useful for accessing the medium via space-division multiplexing, handling over or providing access to location-based contents. In this paper, we present two localization mechanisms based on the wavelength domain by assuming that each anchor point uses a spectrally dedicated signature for the user to readily identify it. The first approach, i.e., wavelength-based localization, assumes a simultaneous transmission of three different pulse streams emitted by the red-green-blue (RGB) light emitting diodes (LEDs). The second method, i.e., colorbased localization, considers the subsequent transmission of RGB pulses. Localization is then computed through traditional received signal strength and time difference of arrival approaches. Moreover, we resort to the properties of metamerism so that the red, green, and blue components used by LEDs provide the white light sensation to the human eye. The performances of the two proposed schemes are close to theoretical bounds. Even in the worst cases, the estimation error variance is in the order of 10-4 m2. Finally, the signaling request for estimating user position is less than others in the literature and is independent from the number of anchor points. Autors: Stefano Pergoloni;Zeinab Mohamadi;Anna Maria Vegni;Zabih Ghassemlooy;Mauro Biagi; Appeared in: Journal of Lightwave Technology Publication date: Jul 2017, volume: 35, issue:14, pages: 2933 - 2942 Publisher: IEEE

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