###### Accueil » Publications dans le domaines des technologies » 10-2017
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 Publications dans les journaux scientifiques dans le domaine de l'ingénierie : 10-2017 trié par par titre, page: 2
» Adaptive Backstepping Control for a Class of Nonlinear Systems With Non-Triangular Structural Uncertainties
 Résumé:In this technical note, a robust adaptive control scheme is proposed based on backstepping techniques for a class of nonlinear systems with unknown parameters. A modeling error may also exist in every state equation or channel and it is bounded by a known function which is allowed to depend on all system states. It is shown that the proposed adaptive control scheme can ensure all signals in the closed-loop system bounded, if the strength of system modeling errors is sufficiently weak. Transient performance is also established. Thus stabilizing systems in classical strict-feedback forms with sufficiently small non-triangular structural perturbations is successfully addressed. In the case that system parameters are known, a non-adaptive robust controller is designed to globally exponentially stabilize such a class of nonlinear systems. Finally simulation studies are used to verify the effectiveness of the proposed scheme. Auteurs: Jianping Cai;Changyun Wen;Hongye Su;Zhitao Liu;Lantao Xing; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5220 - 5226 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Computer-Aided Tuning of Coupled-Resonator Diplexers With Wire $T$ -Junction
 Résumé:This paper is devoted to theoretical and practical issues concerning computer-aided tuning (CAT) of coupled-resonator diplexers with tapped wire T-junction. Special attentions are paid to the following aspects: 1) finding an appropriate circuit model to represent the tapped wire T-junction; 2) developing a legitimate transformation strategy to obtain the coupling matrix of the right form corresponding to the topology of the diplexer containing a tapped wire T-junction; and 3) proposing an adaptive CAT scheme that takes stray couplings into account in a dynamically optimized target coupling matrix. A conventional combline diplexer and a helical resonator diplexer are used as examples to demonstrate the circuit model extraction procedure and the adaptive CAT concept, showing the effectiveness and robustness of the proposed adaptive CAT method for practical applications. Auteurs: Ping Zhao;Ke-Li Wu; Apparue dans: IEEE Transactions on Microwave Theory and Techniques Date publication: 10.-2017, volume: 65, issue:10, pages: 3856 - 3865 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Control of Inertially Actuated Bouncing Robot
 Résumé:This paper presents a vertically jumping robot based on the inertial actuation concept. Recent research studies in our System Laboratory proved that a wide range of inertially actuated locomotion systems can be generated. This can be achieved by using a family tree approach, starting from a very simple system and progressively evolving it to more complex ones. We discovered that inertial actuation was an efficient method to regulate the motion of these robots. The hopper is the most basic member of this tree and efficient control of its motion using inertial actuation is essential to the design of every element in the family. In this work, we introduce an inertially actuated mass-spring system in the vertical plane. The mathematical model is developed and equations of motion for different modes were derived. Then, the nonlinear accessibility is analyzed. Subsequently, an adaptive control scheme was developed in order to generate periodic inertial actuation. We showed that this actuation drives the system toward a stable periodic orbit. Finally, an experimental prototype was built to verify the practical utility of the presented theoretical methods and concepts. Auteurs: Mohammad Kashki;Joe Zoghzoghy;Yildirim Hurmuzlu; Apparue dans: IEEE/ASME Transactions on Mechatronics Date publication: 10.-2017, volume: 22, issue:5, pages: 2196 - 2207 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Driving Bus Voltage and Energy Recycling Control Schemes for Low-Power AC–DC RGB-LED Drivers
 Résumé:A low-power ac-dc light-emitting diode (LED) driver with adaptive driving bus voltage (ADBV) and energy recycling (ER) control schemes is proposed to drive red, green, and blue LEDs in series to achieve high efficiency. The bus voltage of the power factor correction flyback converter with the ADBV control is always adjusted, so as to reduce power loss on current regulators. However, since the small bandwidth of the flyback converter and large bus capacitor limit the transient response of the flyback converter, it is difficult to maintain the voltage across current regulators at the minimum value. The ER control is proposed to accelerate the transient response of the bus voltage, making the voltage across current regulators as close to the minimum voltage as possible. Furthermore, extra energy is stored and restored on the recycling capacitor when the bus voltage is switched between different supplying levels without consuming much power due to the ER control. The experimental waveforms of the laboratory prototype are shown to confirm the validity of the proposed schemes. Auteurs: Pang-Jung Liu;Kai-Lin Peng; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7741 - 7748 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Dynamic Surface Control for a Hypersonic Aircraft Using Neural Networks
 Résumé:A hypersonic aircraft dynamic model is highly nonlinear because its flight conditions are usually determined at high altitude and Mach number. Therefore, there always exist differences between the dynamical model and real system, and uncertainties during the flight, thus, leading significant degradation of control performance. To solve the performance degradation problem, this paper proposes neural networks-based adaptive velocity and altitude tracking controllers. In order for that, the hypersonic aircraft model is transformed into an uncertain feedback system, which has both matched and unmatched uncertainties, by differentiating the velocity and altitude with respect to time. Then, the overall tracking control system is designed systematically by introducing virtual control inputs and dynamic surface control. During the design process, an inverse of an input gain matrix is directly trained and adapted to remove the matched uncertainty and controller singularity problem simultaneously. In addition, several adaptive elements with saturation functions are added to handle all the matched and unmatched uncertainties. The proposed controller guarantees the uniformly ultimate boundedness of the tracking error by utilizing deadzoned errors. Finally, numerical simulations with the uncertain hypersonic aircraft are performed to demonstrate the effectiveness of the proposed approach. Auteurs: Jongho Shin; Apparue dans: IEEE Transactions on Aerospace and Electronic Systems Date publication: 10.-2017, volume: 53, issue:5, pages: 2277 - 2289 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Eulerian Video Processing of Thermal Video: An Experimental Analysis
 Résumé:The use of spatiotemporal video processing to extract biosignals is an emerging technique. This paper aims to build upon current work through robust experimentation and analysis. A blood flow simulation model was captured by thermal and optical cameras, while hot water was pumped through the system. Additionally, five subjects were recruited to perform two experimental trials: a facial perfusion trial and an arm blood occlusion trial, for which subjects sat quietly, while video data were captured using thermal and optical cameras. Each video was subjected to region of interest selection and adaptive Eulerian video magnification (EVM); the iterative application of EVM, first with a wide temporal bandpass filter and low amplification factor and again with a narrower, targeted temporal bandpass filter and higher amplification factor. The results from the simulation experiments indicated that thermal video in conjunction with adaptive EVM processing can reveal variations in temperature indicative of pulse rate in a controlled system of known variables. This process helped to better characterize Eulerian signal enhancement versus Eulerian noise enhancement. The results from the facial perfusion experiments suggest that the adaptive EVM processing of thermal video results in signals representative of facial perfusion rate. The results from the blood occlusion experiments revealed an occlusion temperature pattern, but not a perfusion rate. This paper therefore further demonstrated the potential of thermal video in conjunction with adaptive EVM methods to extract a signal representative of facial perfusion rate, and illustrated the need for more research on thermal video and adaptive EVM. Auteurs: Stephanie Bennett;Tarek Nasser El Harake;Rafik Goubran;Frank Knoefel; Apparue dans: IEEE Transactions on Instrumentation and Measurement Date publication: 10.-2017, volume: 66, issue:10, pages: 2516 - 2524 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Filtering Under a Variable Kernel Width Maximum Correntropy Criterion
 Résumé:The maximum correntropy criterion (MCC) algorithm with constant kernel width leads to a tradeoff problem in terms of convergence rate and steady-state misalignment. Thus, this brief proposes a variable kernel width (VKW) MCC algorithm to overcome this problem. The optimal kernel width of the proposed VKW-MCC algorithm is calculated at each iteration by maximizing ${{\rm exp}(-e_{k}^{2}/2\sigma _{k}^{2})}$ with respect to the kernel width ${ \sigma _{k}}$ , wherein the kernel width is a function of the error, to make the error with greatest attenuation along the direction of the gradient ascent. Simulations in the contexts of system identification and echo cancellation have demonstrated that the proposed VKW-MCC algorithm yields a superior performance. Auteurs: Fuyi Huang;Jiashu Zhang;Sheng Zhang; Apparue dans: IEEE Transactions on Circuits and Systems II: Express Briefs Date publication: 10.-2017, volume: 64, issue:10, pages: 1247 - 1251 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Fuzzy Asymptotic Control of MIMO Systems With Unknown Input Coefficients Via a Robust Nussbaum Gain-Based Approach
 Résumé:This paper proposes an adaptive fuzzy asymptotic control method for multiple input multiple output (MIMO) nonlinear systems with unknown input coefficients, with a focus on handling unknown input nonlinearities and control directions. For all the existing Nussbaum gain-based approaches, it is difficult to investigate unknown input coefficients problem since multiple time-varying coefficients and disturbances coexist and should be simultaneously tackled in the stability analysis. To overcome the above difficulty, we propose a robust Nussbaum gain-based approach for the adaptive fuzzy asymptotic control of MIMO nonlinear systems. Benefiting from the proposed Nussbaum gain-based approach, bounded disturbances including unmodeled system dynamics and universal approximation errors are handled. Furthermore, the proposed approach helps extend the bounded fuzzy control result to the asymptotic convergence. Hence, both the control robustness and control accuracy are prompted within the frame of the developed Nussbaum gain approach. Finally, a simulation example is carried out to illustrate the effectiveness of the proposed control method. Auteurs: Ci Chen;Zhi Liu;Kan Xie;Yanjun Liu;Yun Zhang;C. L. Philip Chen; Apparue dans: IEEE Transactions on Fuzzy Systems Date publication: 10.-2017, volume: 25, issue:5, pages: 1252 - 1263 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Fuzzy Hierarchical Sliding-Mode Control for a Class of MIMO Nonlinear Time-Delay Systems With Input Saturation
 Résumé:In this paper, an adaptive fuzzy hierarchical sliding-mode control method for a class of multiinput multioutput unknown nonlinear time-delay systems with input saturation is proposed. The studied system is first transformed into an equivalent system. Subsequently, based on sliding-mode control technology and the concept of hierarchical design, a set of adaptive fuzzy hierarchical sliding-mode controllers are designed for the new defined system by using fuzzy systems to approximate uncertain functions and compensate input saturation. Choosing an appropriate Lyapunov–Krasovskii function, it is theoretically proved that all the signals in the closed-loop system together with the proposed sliding surfaces are uniformly ultimately bounded under our designed adaptive fuzzy controllers. Simulation results demonstrate the effectiveness of the proposed design techniques for the systems under consideration. Auteurs: Xudong Zhao;Haijiao Yang;Weiguo Xia;Xinyong Wang; Apparue dans: IEEE Transactions on Fuzzy Systems Date publication: 10.-2017, volume: 25, issue:5, pages: 1062 - 1077 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Group Shuffled Decoding for LDPC Codes
 Résumé:We propose new grouping methods for group shuffled (GS) decoding of both regular and irregular low-density parity check cods. These methods are applicable for the belief-propagation as well as the min-sum-based GS decoders. Integer-valued metrics for measuring the reliability of each tentative variable node (VN) decision and the associated likelihood of being corrected are developed. The metrics are used to determine the VN updating priority, so the grouping may vary in each iteration. We estimate the computation complexity needed to adaptively regroup VNs. Numerical results show that our GS algorithms improve the performance of some existing GS belief-propagation decoders. Auteurs: Tofar C.-Y. Chang;Yu T. Su; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2118 - 2121 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Hysteresis Compensation Using Reduced Memory Sequences
 Résumé:Hysteresis in sensors and actuators can often be effectively compensated for by implementing an inverse hysteresis model in series with the sensor or the actuator. However, an apparent problem enters when the hysteresis characteristics vary over time in an unpredicted manner. Here, we derive an adaptive hysteresis compensation method for the case when we only have observations that are very sparse in time and magnitude. Contrary to previous methods it is based on reduced memory sequences and a preidentified initial model, which makes it possible to use only a few adaption parameters. In particular, we investigate the Preisach model (PM). Using a Bernstein polynomial basis for the PM, it is shown that invertibility translates into linear constraints, which ensures that the overall identification problem for the initial PM is convex. The dependence on PM initial conditions may have negative effects on hysteresis compensation and model adaptation. We give general conditions for losing this dependence and also an upper bound for the maximum error it may cause. The method is experimentally applied to a sensor for measurement of torque in a shaft. At times, the shaft is unloaded and consequently the torque can then be independently observed as being zero. This kind of problem leads to a nonlinear parameterization, but with very few parameters to update, which is successfully achieved using an extended Kalman filter. The method essentially removes the effects of hysteresis, fatigue, and aging for the intended use of the sensor. Auteurs: Marcus Nils Hedegärd;Torsten Wik;Christer Wallin; Apparue dans: IEEE/ASME Transactions on Mechatronics Date publication: 10.-2017, volume: 22, issue:5, pages: 2296 - 2307 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Impedance Control of Human–Robot Cooperation Using Reinforcement Learning
 Résumé:This paper presents human-robot cooperation with adaptive behavior of the robot, which helps the human operator to perform the cooperative task and optimizes its performance. A novel adaptive impedance control is proposed for the robotic manipulator, whose end-effector's motions are constrained by human arm motion limits. In order to minimized motion tracking errors and acquire an optimal impedance mode of human arms, the linear quadratic regulation (LQR) is formulated; then, integral reinforcement learning (IRL) has been proposed to solve the given LQR with little information of the human arm model. Considering human-robot interaction force during the robot performing manipulation, a novel barrier-Lyapunov-function-based adaptive impedance control incorporating adaptive parameter learning is developed for physical limits, transient perturbations, and time-varying dynamics. Experimental results validate that the proposed controller is effective in assisting the operator to perform the human-robot cooperative task. Auteurs: Zhijun Li;Junqiang Liu;Zhicong Huang;Yan Peng;Huayan Pu;Liang Ding; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 8013 - 8022 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Inverse Control for Gripper Rotating System in Heavy-Duty Manipulators With Unknown Dead Zones
 Résumé:The gripper rotation system of a heavy-duty manipulator is generally driven by hydraulic motors, and it is difficult to guarantee the accuracy of the rotation angle using conventional control methods due to the existence of dead zones with unknown characteristics. This paper proposes an adaptive inverse dead-zone control method, in which the gradient projection technique is applied to design an adaptive updating law for estimating the inverse dead-zone parameters online. First, a dynamic model of the gripper rotation system is presented with an analysis of its dead-zone characteristics. Then, the controller is designed based on a Takagi-Sugeno fuzzy model, and the estimated values of the inverse dead-zone parameters are shown to converge to their true values. Finally, the performance of the proposed adaptive control method is experimentally demonstrated on an actual forging manipulator. Comparisons with a fixed inverse dead-zone control method demonstrate the effectiveness and applicability of the proposed control method. Auteurs: Hua Deng;Jiehua Luo;Xiaogang Duan;Guoliang Zhong; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7952 - 7961 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Joint Estimation Protocol for Arbitrary Pair of Tag Sets in a Distributed RFID System
 Résumé:Radio frequency identification (RFID) technology has been widely used in Applications, such as inventory control, object tracking, and supply chain management. In this domain, an important research problem is called RFID cardinality estimation, which focuses on estimating the number of tags in a certain area covered by one or multiple readers. This paper extends the research in both temporal and spatial dimensions to provide much richer information about the dynamics of distributed RFID systems. Specifically, we focus on estimating the cardinalities of the intersection/differences/union of two arbitrary tag sets (called joint properties for short) that exist in different spatial or temporal domains. With many practical applications, there is, however, little prior work on this problem. We will propose a joint RFID estimation protocol that supports adaptive snapshot construction. Given the snapshots of any two tag sets, although their lengths may be very different depending on the sizes of tag sets they encode, we design a way to combine their information and more importantly, derive closed-form formulas to use the combined information and estimate the joint properties of the two tag sets, with an accuracy that can be arbitrarily set. By formal analysis, we also determine the optimal system parameters that minimize the execution time of taking snapshots, under the constraints of a given accuracy requirement. We have performed extensive simulations, and the results show that our protocol can reduce the execution time by multiple folds, as compared with the best alternative approach in literature. Auteurs: Qingjun Xiao;Shigang Chen;Min Chen;Yian Zhou;Zhiping Cai;Junzhou Luo; Apparue dans: IEEE/ACM Transactions on Networking Date publication: 10.-2017, volume: 25, issue:5, pages: 2670 - 2685 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Mapper Design for Spatial Modulation with Lightweight Feedback Overhead
 Résumé:The bits-to-antenna-index (BAI) and bits-to-modulated-symbol (BMS) mappings play important roles in determining the bit error rate (BER) of spatial modulation (SM). To minimize the BER, a plenty of work has paid much attention on optimizing the noise-free receive signal constellation diagram via adaptive power allocation, phase ration, precoding, etc, but overlooked the impact of the BAI and BMS mappings. To fill in this gap, this paper investigates the adaptive mapper design for SM, and proposes a mapper solution named brute forth mapper (BFM). Through adjusting the binary labels of all the closest symbol-pairs to be of one bit difference in a brute force way, BFM achieves the optimal BER in high signal-to-noise-ratio (SNR) regime. The feasibility of BFM is proved over random fading channels, and the performance improvement brought by BFM in terms of BER enhancement and SNR gain as well as the computational complexity and feedback overhead are quantitatively analyzed. Both analysis and simulations show that the proposed adaptive mapper significantly improves the BER performance with lightweight feedback overhead. Auteurs: Shuaishuai Guo;Haixia Zhang;Peng Zhang;Dongfeng Yuan; Apparue dans: IEEE Transactions on Vehicular Technology Date publication: 10.-2017, volume: 66, issue:10, pages: 8940 - 8950 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Multi-Objective Evolutionary Algorithms for Overtime Planning in Software Projects
 Résumé:Software engineering and development is well-known to suffer from unplanned overtime, which causes stress and illness in engineers and can lead to poor quality software with higher defects. Recently, we introduced a multi-objective decision support approach to help balance project risks and duration against overtime, so that software engineers can better plan overtime. This approach was empirically evaluated on six real world software projects and compared against state-of-the-art evolutionary approaches and currently used overtime strategies. The results showed that our proposal comfortably outperformed all the benchmarks considered. This paper extends our previous work by investigating adaptive multi-objective approaches to meta-heuristic operator selection, thereby extending and (as the results show) improving algorithmic performance. We also extended our empirical study to include two new real world software projects, thereby enhancing the scientific evidence for the technical performance claims made in the paper. Our new results, over all eight projects studied, showed that our adaptive algorithm outperforms the considered state of the art multi-objective approaches in 93 percent of the experiments (with large effect size). The results also confirm that our approach significantly outperforms current overtime planning practices in 100 percent of the experiments (with large effect size). Auteurs: Federica Sarro;Filomena Ferrucci;Mark Harman;Alessandra Manna;Jian Ren; Apparue dans: IEEE Transactions on Software Engineering Date publication: 10.-2017, volume: 43, issue:10, pages: 898 - 917 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Multimedia Data Forwarding for Privacy Preservation in Vehicular Ad-Hoc Networks
 Résumé:Vehicular ad-hoc networks (VANETs) have drawn much attention of researchers. The vehicles in VANETs frequently join and leave the networks, and therefore restructure the network dynamically and automatically. Forwarded messages in vehicular ad-hoc networks are primarily multimedia data, including structured data, plain text, sound, and video, which require access control with efficient privacy preservation. Ciphertext-policy attribute-based encryption (CP-ABE) is adopted to meet the requirements. However, solutions based on traditional CP-ABE suffer from challenges of the limited computational resources on-board units equipped in the vehicles, especially for the complex policies of encryption and decryption. In this paper, we propose a CP-ABE delegation scheme, which allows road side units (RSUs) to perform most of the computation, for the purpose of improving the decryption efficiency of the vehicles. By using decision tree to jointly optimize multiple factors, such as the distance from RSU, the communication and computational cost, the CP-ABE delegation scheme is adaptively activated based on the estimation of various vehicles decryption overhead. Experimental results thoroughly demonstrate that our scheme is effective and efficient for multimedia data forwarding in vehicular ad-hoc networks with privacy preservation. Auteurs: Yingjie Xia;Wenzhi Chen;Xuejiao Liu;Luming Zhang;Xuelong Li;Yang Xiang; Apparue dans: IEEE Transactions on Intelligent Transportation Systems Date publication: 10.-2017, volume: 18, issue:10, pages: 2629 - 2641 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Nonlocal Sparse Representation for Dual-Camera Compressive Hyperspectral Imaging
 Résumé:Leveraging the compressive sensing (CS) theory, coded aperture snapshot spectral imaging (CASSI) provides an efficient solution to recover 3D hyperspectral data from a 2D measurement. The dual-camera design of CASSI, by adding an uncoded panchromatic measurement, enhances the reconstruction fidelity while maintaining the snapshot advantage. In this paper, we propose an adaptive nonlocal sparse representation (ANSR) model to boost the performance of dual-camera compressive hyperspectral imaging (DCCHI). Specifically, the CS reconstruction problem is formulated as a 3D cube based sparse representation to make full use of the nonlocal similarity in both the spatial and spectral domains. Our key observation is that, the panchromatic image, besides playing the role of direct measurement, can be further exploited to help the nonlocal similarity estimation. Therefore, we design a joint similarity metric by adaptively combining the internal similarity within the reconstructed hyperspectral image and the external similarity within the panchromatic image. In this way, the fidelity of CS reconstruction is greatly enhanced. Both simulation and hardware experimental results show significant improvement of the proposed method over the state-of-the-art. Auteurs: Lizhi Wang;Zhiwei Xiong;Guangming Shi;Feng Wu;Wenjun Zeng; Apparue dans: IEEE Transactions on Pattern Analysis and Machine Intelligence Date publication: 10.-2017, volume: 39, issue:10, pages: 2104 - 2111 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive OFDM Integrated Radar and Communications Waveform Design Based on Information Theory
 Résumé:To improve the effectiveness of limited spectral resources, an adaptive orthogonal frequency division multiplexing integrated radar and communications waveform design method is proposed. First, the conditional mutual information (MI) between the random target impulse response and the received signal, and the data information rate (DIR) of frequency selective fading channel are formulated. Then, with the constraint on the total power, the optimization problem, which simultaneously considers the conditional MI for radar and DIR for communications, is devised, and the analytic solution is derived. With low transmit power, the designed integrated waveform outperforms the fixed waveform (i.e., equal power allocation). Finally, several simulated experiments are provided to verify the effectiveness of the designed waveform. Auteurs: Yongjun Liu;Guisheng Liao;Jingwei Xu;Zhiwei Yang;Yuhong Zhang; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2174 - 2177 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Out-of-Band Interference Suppression for Coexistent Wi-Fi and Bluetooth Systems
 Résumé:Coexistence of Wi-Fi and Bluetooth (BT) systems is often necessary in various handheld devices. Due to nonlinearities of radio frequency front-end components, leakage signals from one transmitter to the other transmitter would produce out-of-band (OOB) interference and corrupt adjacent frequency bands outside the spectral masks defined in standards. In this letter, we propose an adaptive OOB interference suppression scheme based on a modified normalized least mean-squared algorithm for coexistent Wi-Fi and BT transceivers. Computer simulation results show that the proposed approach provides pretty good performance in transmitter leakage cancellation and effectively relieves the OOB interference issue. Auteurs: Chin-Liang Wang;Min-Chau Jan;Yuan-Shuo Chang;Erlang Wang;Ying-Hsi Lin; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2306 - 2309 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Particle Swarm Optimization with Heterogeneous Multicore Parallelism and GPU Acceleration
 Résumé:Much progress has recently been made in global optimization, with particular attention devoted to robust nature-inspired stochastic methods for difficult, high-dimensional problems. This paper presents a computational study of an adaptation of one such method, particle swarm optimization (PSO), which is analyzed for parallelization on readily-available heterogeneous parallel computational hardware: specifically, multicore technologies accelerated by graphics processing units (GPUs), as well as Intel Xeon Phi co-processors accelerated with vectorization. In this heterogeneous approach, computationally-intensive, task-parallel components are performed with multicore parallelism and data-parallel elements are executed via co-processing (GPUs or vectorization). A computationally intensive adaptive PSO technique is parallelized according to this schema. In experiments with two high-dimensional and complex functions, large speedups can be obtained. Thus, a heterogeneous approach mitigates the time complexity of PSO adaptations, suggesting that other time-intensive stochastic methods can also benefit from the techniques proposed here. Auteurs: Mark P. Wachowiak;Mitchell C. Timson;David J. DuVal; Apparue dans: IEEE Transactions on Parallel and Distributed Systems Date publication: 10.-2017, volume: 28, issue:10, pages: 2784 - 2793 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Pulse Compression Technique for X-Band Phased Array Weather Radar
 Résumé:Weather radar commonly uses a matched filter (MF) method to improve the range resolution and signal-to-noise ratio. A X-band phased array weather radar (PAWR), which is capable of 3-D precipitation observations in less than 30 s, is in operation at the Osaka University. The PAWR uses the MF method. In weather radar systems, the magnitude of the range sidelobes is an important topic because it can cause overestimation of the received power from a target, such as precipitation or ground clutter echoes. We propose a minimum mean square error (MMSE)-based pulse compression method to reduce the range sidelobes of the PAWR. We evaluated an MF, an MF with a raised-cosine window, and MMSE methods using numerical simulations and actual measurement data obtained from the PAWR. The results show that the MMSE method is clearly superior to the MF and MF with a raised-cosine filter methods when considering the reduction in the range sidelobes. Auteurs: H. Kikuchi;E. Yoshikawa;T. Ushio;F. Mizutani;M. Wada; Apparue dans: IEEE Geoscience and Remote Sensing Letters Date publication: 10.-2017, volume: 14, issue:10, pages: 1810 - 1814 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Search Range for HEVC Motion Estimation Based on Depth Information
 Résumé:High Efficiency Video Coding achieves twofold coding efficiency improvement compared with its predecessor H.264/MPEG-4 Advanced Video Coding. However, it suffers from high computational complexity due to its quad-tree structure in motion estimation (ME). This paper exposes the use of depth maps in the multiview video plus depth format for relieving the computational burden. The depth map provides an intimation of the objects’ distance from the projected screen in a 3D scene, which is explored in adaptive search range determination in this paper. The proposed algorithm exploits the high temporal correlation between the depth map and the motion in texture. By utilizing this correlation, a depth/motion relationship map is built for a mapping process. For each block, this forms a tailor-made search range with a motion-aware asymmetric shape to skip unnecessary search points in ME. The obtained search range can be further adjusted by taking the influence of 3D-to-2D projection into consideration. Simulation results reveal that, compared to the full search approach, the proposed algorithm can reduce the complexity by 93% on average, whereas the coding efficiency can be maintained. Besides, the proposed search range determination can work well with other fast search ME algorithms in the literature. Auteurs: Tsz-Kwan Lee;Yui-Lam Chan;Wan-Chi Siu; Apparue dans: IEEE Transactions on Circuits and Systems for Video Technology Date publication: 10.-2017, volume: 27, issue:10, pages: 2216 - 2230 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Sliding-Mode Position Control for Dielectric Elastomer Actuators
 Résumé:Multilayer stack transducers made from dielectric elastomers (DEs) generate considerable tensile forces and deformations when they are electrically stimulated. Hence, due to their capacitive behavior, they are energy-efficient substitutes, for example, for conventional electromagnetic drives, and enable various completely new applications. Within this contribution, we present the design of a position control for DE stack actuators electrically fed by a bidirectional flyback converter. Due to the unique property of the flyback converter providing an almost constant feeding power for charging and discharging, the sliding-mode control approach is used for the proposed position control. In a first step, a two-point controller is developed and extended afterwards to a three-point controller with hysteresis to significantly reduce the switching frequency. In order to further improve the control behavior and energy efficiency, an adaptation approach for the inner power converter control is carried out that is used to adapt the hysteresis threshold of the three-point controller. Finally, the experimental validations with a prototypic silicone DE stack actuator and bidirectional flyback converter demonstrate that the proposed adaptive three-point controller combines both high dynamics and accuracy with high efficiency due to a significantly reduced switching frequency. Auteurs: Thorben Hoffstadt;Jürgen Maas; Apparue dans: IEEE/ASME Transactions on Mechatronics Date publication: 10.-2017, volume: 22, issue:5, pages: 2241 - 2251 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Spatial Modulation for Uplink mmWave Communication Systems
 Résumé:In this letter, an adaptive spatial modulation (SM) scheme, in which the spatial signatures of the transmitted signals are adaptively selected according to the channel responses, is proposed for the uplink of a millimeter-wave communication system. We first use an iterative method to search for the spatial signatures that maximize the minimum Euclidean distance of the SM symbols. Following this, a suboptimal scheme is provided to reduce the computational complexity. Numerical results show that the proposed adaptive SM scheme can effectively reduce the system symbol-error rate. Auteurs: Sheng Luo;Xuan Tuong Tran;Kah Chan Teh;Kwok Hung Li; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2178 - 2181 Editeur: IEEE Document complet vers site de l'éditeur
» Adaptive Video Streaming With Network Coding Enabled Named Data Networking
 Résumé:The fast and huge increase of Internet traffic motivates the development of new communication methods that can deal with the growing volume of data traffic. To this aim, named data networking (NDN) has been proposed as a future Internet architecture that enables ubiquitous in-network caching and naturally supports multipath data delivery. Particular attention has been given to using dynamic adaptive streaming over HTTP to enable video streaming in NDN as in both schemes data transmission is triggered and controlled by the clients. However, state-of-the-art works do not consider the multipath capabilities of NDN and the potential improvements that multipath communication brings, such as increased throughput and reliability, which are fundamental for video streaming systems. In this paper, we present a novel architecture for dynamic adaptive streaming over network coding enabled NDN. In comparison to previous works proposing dynamic adaptive streaming over NDN, our architecture exploits network coding to efficiently use the multiple paths connecting the clients to the sources. Moreover, our architecture enables efficient multisource video streaming and improves resiliency to Data packet losses. The experimental evaluation shows that our architecture leads to reduced data traffic load on the sources, increased cache-hit rate at the in-network caches and faster adaptation of the requested video quality by the clients. The performance gains are verified through simulations in a Netflix-like scenario. Auteurs: Jonnahtan Saltarin;Eirina Bourtsoulatze;Nikolaos Thomos;Torsten Braun; Apparue dans: IEEE Transactions on Multimedia Date publication: 10.-2017, volume: 19, issue:10, pages: 2182 - 2196 Editeur: IEEE Document complet vers site de l'éditeur
» Adjustable Microwave Magnetic Spectra of Metamaterials Based on Ferromagnetic Film Laminates
 Résumé:A resonant RLC circuit with a magnetic core has been investigated experimentally and theoretically as a promising metamaterial cell design. Laminates of multilayer ferromagnetic films serve as a magnetic core. The ferromagnetic resonance frequency of the bare laminate core is above 1 GHz. An intensive magnetic absorption peak is obtainable at lower frequencies due to a resonant wire coiled around the core. Such magnetic metamaterials seem promising for applications that require high magnetic loss at frequencies of hundreds of megahertz. This paper focuses on efficient approaches to adjusting the location of magnetic loss peak in magnetic metamaterials. High-frequency permeability of the metamaterial samples has been measured in a rectangular waveguide. It is shown that by varying the geometry, structure, and composition of the measured metamaterial samples, the magnetic spectra can be radically changed. Excitation of electromagnetic resonance in the ferromagnetic core with the resonant wire is discussed within the frame of the quasi-static approximation. Auteurs: S. Y. Bobrovskii;I. T. Iakubov;A. N. Lagarkov;A. V. Osipov;K. N. Rozanov; Apparue dans: IEEE Transactions on Magnetics Date publication: 10.-2017, volume: 53, issue:10, pages: 1 - 6 Editeur: IEEE Document complet vers site de l'éditeur
» ADMM $\supseteq$ Projective Dynamics: Fast Simulation of Hyperelastic Models with Dynamic Constraints
 Résumé:We apply the alternating direction method of multipliers (ADMM) optimization algorithm to implicit time integration of elastic bodies, and show that the resulting method closely relates to the recently proposed projective dynamics algorithm. However, as ADMM is a general purpose optimization algorithm applicable to a broad range of objective functions, it permits the use of nonlinear constitutive models and hard constraints while retaining the speed, parallelizability, and robustness of projective dynamics. We further extend the algorithm to improve the handling of dynamically changing constraints such as sliding and contact, while maintaining the benefits of a constant, prefactored system matrix. We demonstrate the benefits of our algorithm on several examples that include cloth, collisions, and volumetric deformable bodies with nonlinear elasticity and skin sliding effects. Auteurs: Matthew Overby;George E. Brown;Jie Li;Rahul Narain; Apparue dans: IEEE Transactions on Visualization and Computer Graphics Date publication: 10.-2017, volume: 23, issue:10, pages: 2222 - 2234 Editeur: IEEE Document complet vers site de l'éditeur
» Advanced Fast 3-D Electromagnetic Solver for Microwave Tomography Imaging
 Résumé:This paper describes a fast-forward electromagnetic solver (FFS) for the image reconstruction algorithm of our microwave tomography system. Our apparatus is a preclinical prototype of a biomedical imaging system, designed for the purpose of early breast cancer detection. It operates in the 3–6-GHz frequency band using a circular array of probe antennas immersed in a matching liquid; it produces image reconstructions of the permittivity and conductivity profiles of the breast under examination. Our reconstruction algorithm solves the electromagnetic (EM) inverse problem and takes into account the real EM properties of the probe antenna array as well as the influence of the patient’s body and that of the upper metal screen sheet. This FFS algorithm is much faster than conventional EM simulation solvers. In comparison, in the same PC, the CST solver takes ~45 min, while the FFS takes ~1 s of effective simulation time for the same EM model of a numerical breast phantom. Auteurs: Nikolai Simonov;Bo-Ra Kim;Kwang-Jae Lee;Soon-Ik Jeon;Seong-Ho Son; Apparue dans: IEEE Transactions on Medical Imaging Date publication: 10.-2017, volume: 36, issue:10, pages: 2160 - 2170 Editeur: IEEE Document complet vers site de l'éditeur
» Advanced Synchronizing Systems for Offshore Power Systems: Improving System Reliability and Flexibility
 Résumé:Small power systems, such as those found on offshore platforms, are fragile, yet they must operate reliably for economy and the safety of both personnel and the environment. These systems often include combustion turbine generators for the main process power requirements and black start diesel generators that can supply essential and emergency buses; the diesel generators can also be used to restart the main generation systems in the event of a power-system collapse. The power distribution systems on these offshore platforms have built-in redundancy with multiple circuits to supply critical loads for fault tolerance and operating flexibility. A system to easily and safely synchronize islanded buses via many possible synchronization points can revolutionize the operational flexibility and, therefore, the safety and reliability of the power system. This article reports on advanced synchronizing systems installed on two offshore platforms. Auteurs: Michael J. Thompson;Allen Li;Roy Luo;Michael C. Tu;Iris Urdaneta; Apparue dans: IEEE Industry Applications Magazine Date publication: 10.-2017, volume: 23, issue:5, pages: 60 - 69 Editeur: IEEE Document complet vers site de l'éditeur
» Advances in Magnetics Epitaxial Multiferroic Heterostructures and Applications
 Résumé:The ever increasing demand for ultralow power electronics has propelled the exploration of novel multiferroics for realizing voltage control of magnetism in an energy efficient manner. Epitaxial multiferroic heterostructures, possessing a strong lattice-coupled mechanical interface and allowing an electric field (E-field) significantly modulating spin, charge, lattice, and orbital order parameters, have drawn much attention for creating novel magnetoelectric (ME) coupling effects. In this paper, we review the recent progress on control of ME properties in epitaxial multiferroic heterostructures, including their novel physical properties, various strong interfacial ME interactions, and potential applications. Meanwhile, the essential interfacial couplings, allowing cross-tuning of lattice and charge-coupled parameters, have been extensively reviewed. Electric tuning of magnetism in epitaxial multiferroic heterostructures provides a great platform to develop lightweight, compact, and energy-efficient spintronic or electronic devices. Auteurs: Mingmin Zhu;Tianxiang Nan;Bin Peng;Yijun Zhang;Ziyao Zhou;Xi Yang;Wei Ren;Nian X. Sun;Ming Liu; Apparue dans: IEEE Transactions on Magnetics Date publication: 10.-2017, volume: 53, issue:10, pages: 1 - 16 Editeur: IEEE Document complet vers site de l'éditeur
» Aggregating LTE and Wi-Fi: Toward Intra-Cell Fairness and High TCP Performance
 Résumé:The data explosion and resource scarcity of mobile cellular networks require new paradigms to effectively integrate heterogeneous radio resources. Of many candidate approaches, smart aggregation of LTE and Wi-Fi radios is a promising solution that bonds heterogeneous links to meet a mobile terminal’s bandwidth need. Motivated by the existence of a significant number of carrier operated Wi-Fi APs, we propose an easily deployable mechanism, called LTE-W, which efficiently utilizes LTE and Wi-Fi links only with the minimum change of eNodeBs, LTE backhaul networks, and mobile terminals. LTE-W, which is a link-level aggregation mechanism, has the following two key components: 1) mode selection and 2) bearer-split scheduling. First, in the mode selection, LTE-W internally decides who should be served by either LTE-only or LTE-Wi-Fi aggregation considering intra-cell fairness rather than just following users’ intention of aggregation. For the users’ preference to be offered the aggregation service, we choose a bearer (roughly defined in LTE as a set of flows with a similar QoS) as a basic unit of aggregation and propose a smart intra-bearer scheduling algorithm that splits a bearer’s traffic into LTE and Wi-Fi links, considering the performance of TCP flows that take two heterogeneous wireless links. We evaluate our mechanism using the NS-3 with LENA, under various configurations, including nodes with mobility and HTTP traffic, and compare it with a transport-level aggregation mechanism, multipath TCP (MPTCP), demonstrating that LTE-W significantly improves MPTCP, e.g., up to 75% in terms of Jain’s fairness index. Auteurs: Boram Jin;Segi Kim;Donggyu Yun;Hojin Lee;Wooseong Kim;Yung Yi; Apparue dans: IEEE Transactions on Wireless Communications Date publication: 10.-2017, volume: 16, issue:10, pages: 6295 - 6308 Editeur: IEEE Document complet vers site de l'éditeur
» Albedo Retrieval From Multispectral Landsat 8 Observation in Urban Environment: Algorithm Validation by in situ Measurements
 Résumé:The surface albedo in urban environment represents one of the most influencing parameters in the formation of the Urban Heat Island (UHI). Its assessment is therefore strategic to undertake actions for the UHI mitigation: the increase of urban surface reflectivity is an example of cooling strategies increasingly proposed and developed. Spaceborne observations could give a significant contribution supplying albedo maps, and different retrieval algorithms estimating broadband albedo from narrow band reflectivities provided by satellite sensors were proposed and validated in literature. In this study, the accuracy of two well-known retrieval algorithms applied to Landsat 8 OLI reflectivities was assessed in a city of Central Italy (Perugia), selecting test sites having different land cover types. Since the root mean square error of the estimated albedo was quite high (0.07–0.08), a custom retrieval algorithm was developed to evaluate the potential improvement in the narrowband reflectivity-broadband albedo conversion for the case study. This analysis was made possible thanks to an in situ measurement campaign, carried out during the summer months of 2016. The selected sites, having quite homogenous features inside the urban environment, also demonstrated that the albedo values are not significantly affected by the hour of the day, if measurements are taken near noon (variation less than 7%). Spaceborne observations showed once again a powerful tool for monitoring large areas with a quite good spatial resolution (30 m), even if an improvement of the literature albedo retrieval algorithms is required and possible in an urban context. Auteurs: Giorgio Baldinelli;Stefania Bonafoni;Antonella Rotili; Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Date publication: 10.-2017, volume: 10, issue:10, pages: 4504 - 4511 Editeur: IEEE Document complet vers site de l'éditeur
» Algebraic Differential Spatial Modulation Is Capable of Approaching the Performance of Its Coherent Counterpart
 Résumé:We show that certain signal constellations invoked for classic differential encoding result in a phenomenon we term as the unbounded differential constellation size (UDCS). Various existing differential transmission schemes that suffer from this issue are identified. Then, we propose an enhanced algebraic field extension-based differential spatial modulation (AFE-DSM) scheme and its enhanced counterpart that strikes a diversity-rate tradeoff (AFE-DSM-DR), both of which overcome the UDCS issue without compromising its full transmit diversity advantage. Furthermore, the proposed schemes are extended to incorporate amplitude and phase shift keying (APSK) in order to exploit all the available degrees of freedom. Additionally, we propose a pair of detection schemes specially designed for APSK-aided differential transmission schemes. Explicitly, we conceive the buffered minimum mean squared error (B-MMSE) detector and buffered maximum likelihood (B-ML) detector, which exploit the knowledge of previously detected symbols in order to further improve the detection performance. Our simulation results have shown that the proposed detectors are capable of bridging the performance gap between the conventional differential detector (CDD) and the coherent detector that has full channel state information. Specifically, when employing the proposed APSK-aided AFE-DSM scheme operating at a rate of 2 b per channel use, the B-MMSE and B-ML detectors are observed to give about 3- and 3.5-dB signal-to-noise ratio gain with respect to their CDD counterpart at a bit error ratio of $10^{-5}$ . Auteurs: Rakshith Rajashekar;Chao Xu;Naoki Ishikawa;Shinya Sugiura;K. V. S. Hari;Lajos Hanzo; Apparue dans: IEEE Transactions on Communications Date publication: 10.-2017, volume: 65, issue:10, pages: 4260 - 4273 Editeur: IEEE Document complet vers site de l'éditeur
» Algorithms for Accurate Spectral Analysis in the Presence of Arbitrary Noncoherency and Large Distortion
 Résumé:In spectral analysis, achieving coherent sampling, especially when signals have large distortion, has been a challenge for many years. This paper introduces three algorithms to resolve this issue. In comparison to previous algorithms, and two widely used methods in industry: windowing and four-parameter sine wave fit, these new algorithms are capable of obtaining accurate spectral results of the signal, while achieving high accuracy as well as computational efficiency. The novel contribution of this paper is that not only does it propose two new algorithms, but also it analyzes their advantages and limitations in detail, providing their trade-offs and different fields of applications. Extensive simulations and measurements are performed to validate these algorithms. Combined with their high accuracy, computational efficiency, and robustness against signal purity, these algorithms are readily available to be implemented for bench or on-chip testing. In addition, it is suitable for data converter spectral testing when noncoherent sampling is present, and spectrally pure test signal source is not available. Auteurs: Yuming Zhuang;Degang Chen; Apparue dans: IEEE Transactions on Instrumentation and Measurement Date publication: 10.-2017, volume: 66, issue:10, pages: 2556 - 2565 Editeur: IEEE Document complet vers site de l'éditeur
» Aligned Reverse Frame Structure for Interference Mitigation in Dynamic TDD Systems
 Résumé:The dynamic time division duplex (TDD) system has been proposed as a way to meet today’s asymmetrically and dynamically changing traffic demand. However, this approach causes cross-link interference, because neighboring base stations and user elements transmit in opposite directions. In this paper, we investigate and analyze the characteristics of cross-link interference in dynamic TDD systems. Based on this observation, we propose an aligned reverse frame structure to utilize and cancel the cross-link interference. Mathematical analysis and numerical results verify that the proposed scheme achieves performance enhancement in terms of capacity compared with conventional dynamic TDD systems. Auteurs: Kwonjong Lee;Yosub Park;Minsoo Na;Hanho Wang;Daesik Hong; Apparue dans: IEEE Transactions on Wireless Communications Date publication: 10.-2017, volume: 16, issue:10, pages: 6967 - 6978 Editeur: IEEE Document complet vers site de l'éditeur
» All-Fiber-Optics-Based Microwave Photonic Filter With Tunable Center Frequency and Passband Plus Notch
 Résumé:We propose and demonstrate a microwave photonic band-pass filter (MPF), which features a single light source, with continuously and independently tunable center frequency and bandwidth. The center frequency and bandwidth can be adjusted by tuning the variable optical delay line and the position of a spatial filter, respectively. Using a balanced photodetector, the baseband, which is ineradicable in some conventional designs, and the common-mode noise are canceled in our proof-of-concept experiment. Alternatively, a notch with continuously tunable frequency can also be added in the MPF. The experimental measurements of the frequency response of this MPF are demonstrated, which have a good agreement with the theoretical simulations. Auteurs: Xiao Zhang;Chengming Wang;Wenchao Liao;Wenxin Zhang;Shengnan Ai;Zhangkai Peng;Ping Xue; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» All-Optical Actively Mode-Locked Fiber Laser at 2-μm Based on Interband Modulation
 Résumé:In this paper, we have achieved a high repetition rate and tunable pulse generation near ∼2 μm through an all-optical actively mode-locked fiber laser. The performances of the fiber laser have been systematically investigated through numerical simulations. The thulium-doped fiber laser cavity is modulated by the optical injection at 1.55 μm via a nonlinear optical loop mirror in which a specially-designed group-velocity-matching highly nonlinear fiber is incorporated. According to the simulation results, up to 40-GHz pulse train with picosecond tunable pulse width and peak power can be produced. Moreover, the repetition rate can be further enlarged with the help of higher gain. The impacts of gain coefficient, cavity length, and repetition rate on the output are studied in details. The proposed mode-locked fiber laser can be potentially used for future 2- μm fiber communication. Auteurs: Xu Wu;Zhichao Wu;Tianye Huang;Bingwei Chen;Kaixuan Ren;Songnian Fu; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» All-Optical Intensity Modulator by Polarization-Dependent Graphene-Microfiber Waveguide
 Résumé:We demonstrated all-optical intensity modulator based on polarization-dependent graphene-covered microfiber (GMF) waveguide. By controlling the polarization mode of incident light, a greatly adjustable enhanced interaction between the propagating light and the graphene can be obtained via the evanescent field of the microfiber. By employing 980-nm pump light and 1550-nm signal light in continuous wave, the strong light–graphene interaction enables a maximum modulation depth of ∼20.86 dB, and by pumping 980 nm wave pulses, we obtained the temporal response characteristics of signal light with modulation rate of 5.13 kHz. This all-optical intensity modulator is compatible with optical fiber systems, and features with ease of fabrication, and steerable high modulation depth, which show potential in graphene's applications such as all-optical switching and all-optical communications. Auteurs: Ruiduo Wang;Diao Li;Hao Wu;Man Jiang;Zhipei Sun;Yonghui Tian;Jintao Bai;Zhaoyu Ren; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» An Accurate and Fast Converging Short-Term Load Forecasting Model for Industrial Applications in a Smart Grid
 Résumé:Short-term load forecasting (STLF) models are very important for electric industry in the trade of energy. These models have many applications in the day-to-day operations of electric utilities such as energy generation planning, load switching, energy purchasing, infrastructure maintenance, and contract evaluation. A large variety of STLF models have been developed that trade off between forecast accuracy and convergence rate. This paper presents an accurate and fast converging STLF model for industrial applications in a smart grid. In order to improve the forecast accuracy, modifications are devised in two popular techniques: mutual information based feature selection; and enhanced differential evolution algorithm based error minimization. On the other hand, the convergence rate of the overall forecast strategy is enhanced by devising modifications in the heuristic algorithm and in the training process of the artificial neural network. Simulation results show that accuracy of the newly proposed forecast model is 99.5% with moderate execution time, i.e., we have decreased the average execution of the existing bilevel forecast strategy by 52.38%. Auteurs: Ashfaq Ahmad;Nadeem Javaid;Mohsen Guizani;Nabil Alrajeh;Zahoor Ali Khan; Apparue dans: IEEE Transactions on Industrial Informatics Date publication: 10.-2017, volume: 13, issue:5, pages: 2587 - 2596 Editeur: IEEE Document complet vers site de l'éditeur
» An Accurate Method for MPPT to Detect the Partial Shading Occurrence in a PV System
 Résumé:This paper proposes an accurate detection scheme that effectively differentiates the partial shading from the uniform change of irradiance. By doing so, it avoids the unnecessary global peak search which results in a drop of the maximum power point tracker (MPPT) efficiency. The detection is achieved by calculating the irradiance at two designated points on the I–V curve namely, i.e., the short-circuit $(I_{{\text{sc}}})$ and MPP $(I_{{\text{mpp}}})$ currents. Since the mismatch of irradiance at these two points differs greatly for the partial shading and uniform irradiance change, the occurrence of the former is easily discriminated. To prove its effectiveness, the scheme is integrated into perturb and observe and particle swarm optimization MPPT algorithms using a buck–boost converter. Its performance under several partial shading and dynamic shading condition is simulated using MATLAB/Simulink and validated using the dSpace DS1104 platform. It only requires three samples to determine if partial shading occurs; without the scheme, an unnecessary scans of the entire P–V curve is initiated. Consequently, MPPT transient efficiency is increased by 30–35%. In addition to this, the calculated irradiance is utilized to update the open-circuit voltage of the array, thus eliminating the use of temperature and irradiance sensors. Auteurs: Jubaer Ahmed;Zainal Salam; Apparue dans: IEEE Transactions on Industrial Informatics Date publication: 10.-2017, volume: 13, issue:5, pages: 2151 - 2161 Editeur: IEEE Document complet vers site de l'éditeur
» An Accurate Representation of Incoherent Layers Within One-Dimensional Thin-Film Multilayer Structures With Equivalent Propagation Matrices
 Résumé:We propose a novel approach of including incoherent layers into an arbitrary multilayer stack and treating them using the conventional matrix methods in the wave-optics regime. The proposed “Equivalent Matrix Method” (EMM) calculates two phase-shift additions that totally cancel out the interference terms in front of, and behind the incoherent layer. The additions are merged into an equivalent incoherent layer propagation matrix that can be used in the standard coherent calculation. The mathematical model that we describe in the paper has three important advantages. First, the exact calculation of the phase-shift additions efficiently replaces various phase-averaging approaches normally used to deal with incoherency. Second, instead of an incoherent layer, we can use an equivalent coherent layer in a rigorous simulation using the phase-matching. Last, there is no energy imbalance error caused by wave coupling in lossy incoherent layers. We verify the proposed EMM against the general transfer-matrix method (GTMM) and the combined ray optics/wave optics model (CROWM) using two cases: an arbitrary multilayer structure with four incoherent glass layers, and a thin-film hydrogenated amorphous silicon solar cell. In both cases, the EMM yielded the same results as the GTMM and CROWM, thus confirming its regularity. Auteurs: J. Puhan;B. Lipovšek;Á. Bűrmen;I. Fajfar; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 12 Editeur: IEEE Document complet vers site de l'éditeur
» An Accurate Security Game for Low-Resource IoT Devices
 Résumé:The Internet of Things (IoT) technology incorporates a large number of heterogeneous devices connected to untrusted networks. Nevertheless, securing IoT devices is a fundamental issue due to the relevant information handled in IoT networks. The intrusion detection system (IDS) is the most commonly used technique to detect intruders and acts as a second wall of defense when cryptography is broken. This is achieved by combining the advantages of anomaly and signature detection techniques, which are characterized by high detection rates and low false positives, respectively. To achieve a high detection rate, the anomaly detection technique relies on a learning algorithm to model the normal behavior of a node, and when a new attack pattern (often known as signature) is detected, it will be modeled with a set of rules. This latter is used by the signature detection technique for attack confirmation. Activating the anomaly detection technique simultaneously at each low-resource IoT device and all the time could generate a high-energy consumption. Thereby, we propose a game theoretic technique to activate anomaly detection technique only when a new attack's signature is expected to occur; hence, a balance between detection and false positive rates, and energy consumption is achieved. Even by combining between these two detection techniques, we observed that the number of false positives is still non null (almost equal to 5%). Thereby, to decrease further the false positive rate, a reputation model based on game theory is proposed. Simulation results show that this lightweight anomaly detection outperforms current anomaly detection techniques, since in scaling mode (i.e., when the number of IoT devices and attackers are high) it requires low energy consumption to detect the attacks with high detection and low false positive rates, almost 93% and 2%, respectively. Auteurs: Hichem Sedjelmaci;Sidi Mohamed Senouci;Tarik Taleb; Apparue dans: IEEE Transactions on Vehicular Technology Date publication: 10.-2017, volume: 66, issue:10, pages: 9381 - 9393 Editeur: IEEE Document complet vers site de l'éditeur
» An Achievable Rate Region Based on Coset Codes for Multiple Access Channel With States
 Résumé:We prove that the ensemble of the nested coset codes built on finite fields achieves the capacity of arbitrary discrete memoryless point-to-point channels. Exploiting its algebraic structure, we develop a coding technique for communication over general discrete multiple access channel with channel state information distributed noncausally at the transmitters. We build an algebraic coding framework for this problem using the ensemble of Abelian group codes and, thereby, derive a new achievable rate region. We identify non-additive and non-symmetric examples for which the proposed achievable rate region is strictly larger than the one achievable using random unstructured codes. Auteurs: Arun Padakandla;S. Sandeep Pradhan; Apparue dans: IEEE Transactions on Information Theory Date publication: 10.-2017, volume: 63, issue:10, pages: 6393 - 6415 Editeur: IEEE Document complet vers site de l'éditeur
» An Adaptive Fixed-Point Iteration Algorithm for Finite-Element Analysis With Magnetic Hysteresis Materials
 Résumé:In this paper, an adaptive fixed-point iteration algorithm for 2-D/3-D finite-element analysis with hysteresis is proposed. The iteration starts with the $B$ -correction scheme. If the solution is not converged to a given accuracy after a certain number of iterations, the iteration will be continued by switching to the $H$ -correction scheme. Based on the combined use of the two correction schemes during the whole iteration process, the solution with the minimum error together with the scheme type is recorded and will be used as the final solution at the current time step. At the same time, the recorded scheme type will be used as the initial scheme type for the next time step. The numerical validation shows that the proposed algorithm not only has very fast convergence rate, but is also very stable. Auteurs: P. Zhou;D. Lin;C. Lu;M. Rosu;D. M. Ionel; Apparue dans: IEEE Transactions on Magnetics Date publication: 10.-2017, volume: 53, issue:10, pages: 1 - 5 Editeur: IEEE Document complet vers site de l'éditeur
» An Adaptive PAM-4 Analog Equalizer With Boosting-State Detection in the Time Domain
 Résumé:This paper introduces an improved adaptive analog equalizer that is required in high speed serial receivers using four-level pulse amplitude modulation signaling. By performing boosting-state detection in the time domain, the proposed adaptive analog equalizer can effectively overcome a serious problem that the received signal’s eye-opening tends to be compromised by the convergence accuracy of the adaptive control loop. To suppress the pattern-dependent jitters (PDJs), an inductor-less, cross-stage feedback structure is employed in the proposed analog equalizer to help broaden its effective tuning bandwidth. Multichannel simulations have confirmed that the proposed equalizer is able to achieve a 42% improvement in eye-height opening when compared with the equalizers employing popular spectrum-comparing schemes. Trellis diagram analyses under different date rates have revealed that the bandwidth of the proposed equalizer can be extended by as much as 60%, thus effectively bringing the PDJs from 44% down to 27.5%. Auteurs: Shunbin Li;Yingtao Jiang;Peng Liu; Apparue dans: IEEE Transactions on Very Large Scale Integration Systems Date publication: 10.-2017, volume: 25, issue:10, pages: 2907 - 2916 Editeur: IEEE Document complet vers site de l'éditeur
» An Adaptive Strips Method for Extraction Buildings From Light Detection and Ranging Data
 Résumé:A method is proposed for extracting building points set from light detecting and ranging (LiDAR) data. This proposed method is based on a strip strategy to filter building points and extract the edge point set rapidly and effectively in large-scale urban building groups. This approach divides the LiDAR data into small strips and classifies each strip of data with an adaptive-weight polynomial in the $x$ - or $y$ -direction. The building edge set can then be extracted by utilizing the regional clustering relationships between points. The results of a series of experiments show that our method can not only filter the LiDAR point cloud, which performs better than existing methods, but also determine the building edge set efficiently, with an average accuracy rate of up to 91.1%. Auteurs: Xionggao Zou;Yueping Feng;Huiying Li;Jinlong Zhu; Apparue dans: IEEE Geoscience and Remote Sensing Letters Date publication: 10.-2017, volume: 14, issue:10, pages: 1651 - 1655 Editeur: IEEE Document complet vers site de l'éditeur
» An Algorithm for Motif-Based Network Design
 Résumé:A determinant property of the structure of a biological network is the distribution of local connectivity patterns, i.e., network motifs. In this work, a method for creating directed, unweighted networks while promoting a certain combination of motifs is presented. This motif-based network algorithm starts with an empty graph and randomly connects the nodes by advancing or discouraging the formation of chosen motifs. The in- or out-degree distribution of the generated networks can be explicitly chosen. The algorithm is shown to perform well in producing networks with high occurrences of the targeted motifs, both ones consisting of three nodes as well as ones consisting of four nodes. Moreover, the algorithm can also be tuned to bring about global network characteristics found in many natural networks, such as small-worldness and modularity. Auteurs: Tuomo Mäki-Marttunen; Apparue dans: IEEE/ACM Transactions on Computational Biology and Bioinformatics Date publication: 10.-2017, volume: 14, issue:5, pages: 1181 - 1186 Editeur: IEEE Document complet vers site de l'éditeur
» An Analog Front-End Chip With Self-Calibrated Input Impedance for Monitoring of Biosignals via Dry Electrode-Skin Interfaces
 Résumé:This paper demonstrates an input impedance boosting method that was developed for long-term monitoring of electroencephalography signals. An instrumentation amplifier was designed with a negative capacitance generation feedback (NCGFB) technique to cancel the adverse effects of input capacitances from electrode cables and printed circuit boards. The NCGFB boosts the measured impedance from below 40 M $\Omega$ to above 500 M $\Omega$ at 50 Hz when the equivalent capacitance at the inputs is up to 150 pF. The prototype chip includes an automatic calibration system to adaptively enhance the input impedance through on-chip test signal generation, measurement, and the automatic digital control of the NCGFB. Consisting of an instrumentation amplifier, a low-pass notch filter, and a variable gain amplifier in 130-nm CMOS technology, the signal path has a combined gain range of 66–93 dB with a total power consumption of 42 $\mu$ W. The front-end bandwidth covers 0.5–48 Hz, and its integrated input-referred noise over the bandwidth is 3.75 $\mu$ Vrms. The measured third-order harmonic distortion component is at least 57 dB below the fundamental signal level. A common-mode rejection ratio of 77.6 dB and a power supply rejection ratio of 74 dB were measured at 10 Hz. When activated, the auxiliary test signal generation and calibration circuits consume a power of 542 $\mu$ W. Auteurs: Chun-Hsiang Chang;Seyed Alireza Zahrai;Kainan Wang;Li Xu;Ibrahim Farah;Marvin Onabajo; Apparue dans: IEEE Transactions on Circuits and Systems I: Regular Papers Date publication: 10.-2017, volume: 64, issue:10, pages: 2666 - 2678 Editeur: IEEE Document complet vers site de l'éditeur
» An Analytical Approach to Detect Generator Loss of Excitation Based on Internal Voltage Calculation
 Résumé:The excitation system of a synchronous generator has a major role in proper operation and control of the generator. Loss of excitation (LOE) may cause harmful effects on the both generator and power system. This paper presents a new approach to detect LOE based on calculating the synchronous generator internal voltage. This parameter is considerably sensitive to LOE and can be used as a straightforward index to discriminate LOE events from system disturbances more quickly and robustly than the conventional indices. A novel and practical technique with minimum computational burden is presented to calculate the generator internal voltage. To evaluate the proposed algorithm, LOE events in a multimachine test system are investigated. In addition, the proposed approach is experimentally evaluated on a 10 kVA synchronous generator. Performed studies demonstrate that the proposed strategy not only noticeably decreases the LOE relay operation time, but also desensitizes its maloperation to system disturbances. Auteurs: Moein Abedini;Majid Sanaye-Pasand;Mahdi Davarpanah; Apparue dans: IEEE Transactions on Power Delivery Date publication: 10.-2017, volume: 32, issue:5, pages: 2329 - 2338 Editeur: IEEE Document complet vers site de l'éditeur
» An Analytical Solution to Optimal Stator Current Design for PMSM Torque Ripple Minimization With Minimal Machine Losses
 Résumé:This paper investigates torque ripple minimization for permanent-magnet synchronous machines (PMSM), and proposes a novel analytical solution of optimal stator current design for torque ripple minimization. The proposed design is theoretically proven to be able to minimize the torque ripple with minimal machine losses. Moreover, the optimal stator current is computed from analytical expression, which is computationally efficient. Therefore, the proposed approach is applicable for torque ripple minimization under both transient state and steady state. However, existing approaches usually employ optimization algorithm to optimize the stator current, which is computationally complex and involves iterative computation, so their applicability is limited under transient state, because the optimal stator current must be adaptively updated with respect to operating conditions. Moreover, magnetic saturation is considered in the proposed approach by employing a novel linear model to model the relation between the inductance and the stator current under maximum torque per ampere (MTPA) control. In this way, the proposed analytical solution does not involve inductance, and thus, the influence of magnetic saturation can be effectively reduced. The proposed approach is validated on a laboratory PMSM drive system under both transient state and steady state. Auteurs: Guodong Feng;Chunyan Lai;Narayan C. Kar; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7655 - 7665 Editeur: IEEE Document complet vers site de l'éditeur
» An Annotation Agnostic Algorithm for Detecting Nascent RNA Transcripts in GRO-Seq
 Résumé:We present a fast and simple algorithm to detect nascent RNA transcription in global nuclear run-on sequencing (GRO-seq). GRO-seq is a relatively new protocol that captures nascent transcripts from actively engaged polymerase, providing a direct read-out on bona fide transcription. Most traditional assays, such as RNA-seq, measure steady state RNA levels which are affected by transcription, post-transcriptional processing, and RNA stability. GRO-seq data, however, presents unique analysis challenges that are only beginning to be addressed. Here, we describe a new algorithm, Fast Read Stitcher (FStitch), that takes advantage of two popular machine-learning techniques, hidden Markov models and logistic regression, to classify which regions of the genome are transcribed. Given a small user-defined training set, our algorithm is accurate, robust to varying read depth, annotation agnostic, and fast. Analysis of GRO-seq data without a priori need for annotation uncovers surprising new insights into several aspects of the transcription process. Auteurs: Joseph G. Azofeifa;Mary A. Allen;Manuel E. Lladser;Robin D. Dowell; Apparue dans: IEEE/ACM Transactions on Computational Biology and Bioinformatics Date publication: 10.-2017, volume: 14, issue:5, pages: 1070 - 1081 Editeur: IEEE Document complet vers site de l'éditeur
» An Annulus-Sector Segmented Primary Mirror
 Résumé:Ultrahigh resolution optical imaging with large aperture is increasingly desired in space-based remote sensing and imaging system, but it is usually limited by volume and mass constraints of launch vehicle due to size and weight of the imaging system. In this paper, an annulus-sector segment primary mirror is presented, which is in high obscuration with circularity symmetrical annulus-sector around. The different structure types of the annulus-sector segment aperture are discussed, while two important parameters, width–diameter ratio and the subaperture angle are also studied. An annulus-sector optical lens is processed to verify the image performance. Experimental results show that modulation transfer function of annulus-sector segment optical system can be up to 0.23(50 lp/mm), which approaches the optical resolution of full aperture optical system with smaller size and lighter weight. Auteurs: X. X. Wei;X. J. Wan;B. Yang; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 9 Editeur: IEEE Document complet vers site de l'éditeur
» An Approach for Building Efficient and Accurate Social Recommender Systems Using Individual Relationship Networks
 Résumé:Social recommender system, using social relation networks as additional input to improve the accuracy of traditional recommender systems, has become an important research topic. However, most existing methods utilize the entire user relationship network with no consideration to its huge size, sparsity, imbalance, and noise issues. This may degrade the efficiency and accuracy of social recommender systems. This study proposes a new approach to manage the complexity of adding social relation networks to recommender systems. Our method first generates an individual relationship network (IRN) for each user and item by developing a novel fitting algorithm of relationship networks to control the relationship propagation and contracting. We then fuse matrix factorization with social regularization and the neighborhood model using IRN's to generate recommendations. Our approach is quite general, and can also be applied to the item-item relationship network by switching the roles of users and items. Experiments on four datasets with different sizes, sparsity levels, and relationship types show that our approach can improve predictive accuracy and gain a better scalability compared with state-of-the-art social recommendation methods. Auteurs: Surong Yan;Kwei-Jay Lin;Xiaolin Zheng;Wenyu Zhang;Xiaoqing Feng; Apparue dans: IEEE Transactions on Knowledge and Data Engineering Date publication: 10.-2017, volume: 29, issue:10, pages: 2086 - 2099 Editeur: IEEE Document complet vers site de l'éditeur
» An E-Mode p-Channel GaN MOSHFET for a CMOS Compatible PMIC
 Résumé:The operation principle of a low power E-mode p-channel GaN MOSHFET is explained via TCAD simulations. The challenges of achieving negative threshold voltage with the scaling of gate length are addressed by adjusting the mole fraction of an AlGaN cap layer beneath the gate. An inverter consisting of the proposed p-channel GaN MOSHFET with a gate length of $0.25~\mu \text{m}$ shows promise of a CMOS compatible power management IC in the megahertz range. Auteurs: Ashwani Kumar;Maria Merlyne De Souza; Apparue dans: IEEE Electron Device Letters Date publication: 10.-2017, volume: 38, issue:10, pages: 1449 - 1452 Editeur: IEEE Document complet vers site de l'éditeur
» An Efficient Algorithm for Optimally Reshaping the TP Model Transformation
 Résumé:The tensor product (TP) model transformation is an emerging technique for the ongoing system analysis and design works of recent years, where its integration with the linear matrix inequalities (LMIs)-based methods can be powerful solution. However, one of the main issues is encountered that the performance of the LMI conditions depends heavily on the tightness of the TP models. This brief proposes an efficient TP model reshaping algorithm toward tightening TP models. A novel index is introduced to quantize the tightness of TP models such that an optimal reshaping can be realized. Besides, a random search following a recursive reshaping strategy is developed, which intensively enhances the efficiency of the reshaping process. The efficiency and effectiveness of the algorithm are demonstrated via a series of numerical simulations. Auteurs: Xiangdong Liu;Yin Yu;Zhen Li;Herbert H. C. Iu;Tyrone Fernando; Apparue dans: IEEE Transactions on Circuits and Systems II: Express Briefs Date publication: 10.-2017, volume: 64, issue:10, pages: 1187 - 1191 Editeur: IEEE Document complet vers site de l'éditeur
» An Efficient and Stable 2-D/3-D Hybrid Discontinuous Galerkin Time-Domain Analysis With Adaptive Criterion for Arbitrarily Shaped Antipads in Dispersive Parallel-Plate Pair
 Résumé:A hybrid 2-D and 3-D discontinuous Garlerkin time-domain (DGTD) method is proposed for transient analysis of multiple arbitrarily shaped antipads in a dispersive parallel-plate pair. In the proposed hybrid method, the domains where only the zeroth-order parallel-plate mode exists are modeled by the 2-D DGTD, and the remaining domains are modeled by the 3-D DGTD. Each element is independent with others, thus easily parallelizable. Because higher order modes will propagate in the parallel-plate pair, the spatial domain decomposition should be time-dependent. For domain decomposition criterion at time step $\text {t}_{\text {n}}$ , the electromagnetic field distribution at the previous time step $\text {t}_{\text {n-1}}$ is analyzed to identify the zeroth-order parallel mode domain. Compared with the classical static distance criterion, this new adaptive criterion makes the approximation error under control, thus enhancing the stability. The accuracy and flexibility of the hybrid method have been validated by comparison with commercial software. Its enhancement of efficiency and stability is also demonstrated. Auteurs: Wending Mai;Jun Hu;Ping Li;Huapeng Zhao; Apparue dans: IEEE Transactions on Microwave Theory and Techniques Date publication: 10.-2017, volume: 65, issue:10, pages: 3671 - 3681 Editeur: IEEE Document complet vers site de l'éditeur
» An Efficient Buck/Buck-Boost Reconfigurable LED Driver Employing SIN2 Reference
 Résumé:An efficient buck/buck-boost reconfigurable LED driver based on peak current control is introduced. The driver supports pulse-width modulation (PWM) and pulse-frequency modulation (PFM) operations. The use of a combination of rectified sin and sin2 functions in the reference is introduced for the purpose of improving the power factor (PF) and total harmonic distortion (THD) of buck and buck-boost converters. The optimal reference waveform shape for buck and buck/boost modes can be set externally. The design ensures that the peak of the inductor current maintains a constant level that is invariant for different ac line voltages. The LED driver has been implemented in a 130-nm CMOS process. PF and THD are improved when the proposed reference is employed, and the peak PF and lowest THD values are 0.995/0.983/0.996 and 7.8/6.2/3.5% for the buck (PWM), buck (PFM), and buck-boost (PFM) cases, respectively. The corresponding peak efficiency for the three cases is 88/92/91%, respectively. Auteurs: Kunhee Cho;Ranjit Gharpurey; Apparue dans: IEEE Journal of Solid-State Circuits Date publication: 10.-2017, volume: 52, issue:10, pages: 2758 - 2768 Editeur: IEEE Document complet vers site de l'éditeur
» An Efficient Contrast Enhancement Method for Remote Sensing Images
 Résumé:Remote sensing images often suffer low contrast. Although many contrast enhancement methods have been proposed in recent literature, the efficiency and robustness of remote sensing image contrast enhancement is still a challenge. In this letter, a novel self-adaptive histogram compacting transform-based contrast enhancement method for remote sensing images is presented to meet with the requirements of automation, robustness, and efficiency in applications. First, the histogram of an input image is optimized into compact and continuous status with the constraints of the merging cost, the moderate global brightness, and the entropy contribution of gray levels. Then, a local remapping algorithm is proposed to catch more details during the course of gray extending with the linear stretch. Finally, a dual-gamma transform is proposed to enhance the contrast in both bright and black areas. Experimental and comparison results demonstrate that the proposed method yields better results than the state-of-the-art methods and maintains robustness in different cases. It provides an effective approach for remote sensing image automatic contrast enhancement. Auteurs: Jiahang Liu;Chenghu Zhou;Peng Chen;Chaomeng Kang; Apparue dans: IEEE Geoscience and Remote Sensing Letters Date publication: 10.-2017, volume: 14, issue:10, pages: 1715 - 1719 Editeur: IEEE Document complet vers site de l'éditeur
» An Efficient Hierarchical Banking Structure for Algorithmic Multiported Memory on FPGA
 Résumé:Algorithmic multiported memory supports concurrent accesses by cooperating block RAMs (BRAMs) with algorithmic operations, and demonstrates the better performance per resource usage on FPGA when compared with register-based designs. However, the current approaches still use significant amount of FPGA resources and pose great design challenges when increasing the access ports. This paper proposes HB-NTX with a resource efficient hierarchical banking structure for nontable-based multi-ported memory design on FPGA. The regular design style enables a systematic flow to scale both read and write ports. When compared with the previous approaches, HB-NTX can reduce 62.03% BRAMs when composing a 2R4W memory with 32K depth. This paper further extends the HB-NTX to alleviate the complexity of the table-based memory designs. When compared with the previous table-based TBLVT approach, the proposed design for a 2R4W memory with 8K depth attains the cost reduction of 39.9%, 14.3%, and 15.6%, for registers, lookup tables, and BRAMs, respectively. Auteurs: Bo-Cheng Charles Lai;Kun-Hua Huang; Apparue dans: IEEE Transactions on Very Large Scale Integration Systems Date publication: 10.-2017, volume: 25, issue:10, pages: 2776 - 2788 Editeur: IEEE Document complet vers site de l'éditeur
» An Efficient Load Balancing of Gateways Using Improved Shuffled Frog Leaping Algorithm and Novel Fitness Function for WSNs
 Résumé:Energy consumption is one of the important factors in wireless sensor networks (WSNs) design. As energy is a limited resource, energy consumption problem in WSNs has become a fast growing problem, and there is a need of efficient and robust algorithms for load balancing in WSNs. This energy is needed for sensor nodes operations. In order to maximize the network lifetime, energy consumption should be optimized. In cluster-based WSNs, cluster heads or gateways perform activities, such as data collection from its member nodes, data aggregation, and data exchange with the base station. Hence, load balancing of gateways in WSNs is one of the crucial and challenging tasks to maximize network lifetime. In order to address this problem, in this paper, shuffled frog leaping algorithm (SFLA) is improved by suitably modifying the frog’s population generation and off-spring generation phases in SFLA and by introducing a transfer phase. A novel fitness function is also designed to evaluate the quality of the solutions produced by the improved SFLA. We performed extensive simulations of the proposed load balancing algorithm in terms of various performance parameters. The experimental results are encouraging and demonstrated the efficiency of the proposed algorithm. Auteurs: Damodar Reddy Edla;Amruta Lipare;Ramalingaswamy Cheruku;Venkatanareshbabu Kuppili; Apparue dans: IEEE Sensors Journal Date publication: 10.-2017, volume: 17, issue:20, pages: 6724 - 6733 Editeur: IEEE Document complet vers site de l'éditeur
» An Efficient Online Algorithm for Dynamic SDN Controller Assignment in Data Center Networks
 Résumé:Software defined networking is increasingly prevalent in data center networks for it enables centralized network configuration and management. However, since switches are statically assigned to controllers and controllers are statically provisioned, traffic dynamics may cause long response time and incur high maintenance cost. To address these issues, we formulate the dynamic controller assignment problem (DCAP) as an online optimization to minimize the total cost caused by response time and maintenance on the cluster of controllers. By applying the randomized fixed horizon control framework, we decompose DCAP into a series of stable matching problems with transfers, guaranteeing a small loss in competitive ratio. Since the matching problem is NP-hard, we propose a hierarchical two-phase algorithm that integrates key concepts from both matching theory and coalitional games to solve it efficiently. Theoretical analysis proves that our algorithm converges to a near-optimal Nash stable solution within tens of iterations. Extensive simulations show that our online approach reduces total cost by about 46%, and achieves better load balancing among controllers compared with static assignment. Auteurs: Tao Wang;Fangming Liu;Hong Xu; Apparue dans: IEEE/ACM Transactions on Networking Date publication: 10.-2017, volume: 25, issue:5, pages: 2788 - 2801 Editeur: IEEE Document complet vers site de l'éditeur
» An Efficient Polyphase Filter-Based Resampling Method for Unifying the PRFs in SAR Data
 Résumé:Variable higher pulse repetition frequencies (PRFs) are increasingly being used to meet the stricter requirements and complexities of current airborne and spaceborne synthetic aperture radar (SAR) systems associated with higher resolution and wider area products. POLYPHASE, the proposed resampling scheme, downsamples and unifies variable PRFs within a single look complex SAR acquisition and across a repeat pass sequence of acquisitions down to an effective lower PRF. A sparsity condition of the received SAR data ensures that the uniformly resampled data approximate the spectral properties of a decimated densely sampled version of the received SAR data. While experiments conducted with both synthetically generated and real airborne SAR data show that POLYPHASE retains comparable performance with the state-of-the-art best linear unbiased interpolation scheme in image quality, a polyphase filter-based implementation of POLYPHASE offers significant computational savings for arbitrary (not necessarily periodic) input PRF variations, thus allowing fully on-board, in-place, and real-time implementation. Auteurs: Yoangel Torres;Kamal Premaratne;Falk Amelung;Shimon Wdowinski; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5741 - 5754 Editeur: IEEE Document complet vers site de l'éditeur
» An Efficient Privacy-Preserving Outsourced Computation over Public Data
 Résumé:In this paper, we propose a new efficient privacy-preserving outsourced computation framework over public data, called EPOC. EPOC allows a user to outsource the computation of a function over multi-dimensional public data to the cloud while protecting the privacy of the function and its output. Specifically, we introduce three types of EPOC in order to tradeoff different levels of privacy protection and performance. We present a new cryptosystem called Switchable Homomorphic Encryption with Partially Decryption (SHED) as the core cryptographic primitive for EPOC. We introduce two coding techniques, called message pre-coding technique and message extending and coding technique respectively, for messages encrypted under a composite order group. Furthermore, we propose a Secure Exponent Calculation Protocol with Public Base (SEPB), which serves as the core sub-protocol in EPOC. Detailed security analysis shows that the proposed EPOC achieves the goal of outsourcing computation of a private function over public data without privacy leakage to unauthorized parties. In addition, performance evaluations via extensive simulations demonstrate that EPOC is efficient in both computation and communications. Auteurs: Ximeng Liu;Baodong Qin;Robert H. Deng;Yingjiu Li; Apparue dans: IEEE Transactions on Services Computing Date publication: 10.-2017, volume: 10, issue:5, pages: 756 - 770 Editeur: IEEE Document complet vers site de l'éditeur
» An Efficient Procedure for Bilayer-Expurgated LDPC Codes Design in Cooperative Relay Channels
 Résumé:This letter proposes a fast optimization procedure to design bilayer-expurgated low density parity check codes in the relay channel. The code optimization problem aims to maximize the code rate while guaranteeing the convergence of the density evolution relations in upper and lower layer codes. The original problem is linear programming. Nevertheless, it suffers from high computational complexity, as it is semi-infinite programming (SIP) in a 2-D continuous interval. To efficiently solve it, we first approximate the density evolutions by polynomials. Then, leveraging optimization problems over the solution of sum of square multivariate polynomials the problem is transformed to semi-definite programming (SDP), where the global solution can be found efficiently using available SDP solvers. Our simulation shows that our approach results in significantly lower computational complexity with respect to the well-known method of quantization for solving the SIP problem, while both achieve the same performance. Auteurs: Sajad Mehrizi;Sara Khosravi;Mahmoud Ahmadian; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2114 - 2117 Editeur: IEEE Document complet vers site de l'éditeur
» An Eigen-Binding Site Based Method for the Analysis of Anti-EGFR Drug Resistance in Lung Cancer Treatment
 Résumé:We explore the drug resistance mechanism in non-small cell lung cancer treatment by characterizing the drug-binding site of a protein mutant based on local surface and energy features. These features are transformed to an eigen-binding site space and used for drug resistance level prediction and analysis. Auteurs: Lichun Ma;Debby D. Wang;Bin Zou;Hong Yan; Apparue dans: IEEE/ACM Transactions on Computational Biology and Bioinformatics Date publication: 10.-2017, volume: 14, issue:5, pages: 1187 - 1194 Editeur: IEEE Document complet vers site de l'éditeur
» An End-Member-Based Two-Source Approach for Estimating Land Surface Evapotranspiration From Remote Sensing Data
 Résumé:Evapotranspiration (ET) is one of the key variables in the water and energy exchange between land surface and atmosphere. This paper develops an end-member-based two-source approach for estimating land surface ET (i.e., the ESVEP model) from remote sensing data, considering the differing responses of soil water content at the upper surface layer to soil evaporation and at the deeper root zone layer to vegetation transpiration. The ESVEP model first diverges the soil-vegetation system net radiation into soil and vegetation components by considering the transmission of direct and diffuse shortwave radiation separately from the transmission of longwave radiation through the canopy, then calculates the four dry/wet soil/vegetation end-members with the diverged soil and vegetation net radiations, and last separates soil evaporation from vegetation transpiration based on the two-phase ET dynamics and the four end-member temperatures. The model can overall produce reasonably good surface energy fluxes and is no more sensitive to meteorology, vegetation, and remote sensing inputs than other two-source energy balance models and surface temperature versus vegetation index ( $T_{R}$ –VI) trapezoid models. A reasonable agreement could be found with a small bias of ±8 W/ $\text{m}^{2}$ and a root-mean-square error within 60 W/ $\text{m}^{2}$ (comparable to accuracies published in other studies) when both model-estimated sensible heat flux and latent heat flux from MODIS remote sensing data are validated with ground-based large aperture scintillometer measurements. Auteurs: Ronglin Tang;Zhao-Liang Li; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5818 - 5832 Editeur: IEEE Document complet vers site de l'éditeur
» An Enhanced Access Reservation Protocol With a Partial Preamble Transmission Mechanism in NB-IoT Systems
 Résumé:We propose an enhanced access reservation protocol (ARP) with a partial preamble transmission mechanism for the narrow band Internet of Things (NB-IoT) systems. The proposed ARP can enhance the ARP performance by mitigating the occurrence of preamble collisions, while being compatible with the conventional NB-IoT ARP. We provide an analytical model that captures the performance of the proposed ARP in terms of false alarm, misdetection, and collision probabilities. Moreover, we investigate a tradeoff between the misdetection and the collision probabilities, and optimize the proposed ARP according to the system loads. The results show that the proposed ARP outperforms the conventional NB-IoT ARP, in particular, at heavier system loads. Auteurs: Taehoon Kim;Dong Min Kim;Nuno Pratas;Petar Popovski;Dan Keun Sung; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2270 - 2273 Editeur: IEEE Document complet vers site de l'éditeur
» An Equivalent Circuit Model for Nested Split-Ring Resonators
 Résumé:In this paper, an equivalent circuit model for nested split-ring resonators (NSRRs) is proposed. NSRRs are an emerging class of split ring resonators, preferred in a range of areas from sensing in biomedical or civil engineering applications to antenna design, due to their more compact size and enhanced sensitivity/resolution characteristics over the conventional SRRs. In the proposed model, the NSRR structure is treated as a combination of basic elements, i.e., strips and gaps, and the electromagnetic characteristics of the whole geometry are expressed in terms of capacitances and inductances of each of these elements. The outputs of the model are compared with those obtained via full-wave simulations using the package programs as well as measurements. The variation of NSRR resonance frequency ( $f_{\text {res}}$ ) with all important design parameters is also compared with full-wave simulations. In all comparisons, the results demonstrate agreement, showing that the proposed model can correctly explain the electromagnetics of the NSRR structure and that it provides an intuitive way for a better and easier analysis and a preliminary design of normally complex structures. Auteurs: Burak Ozbey;Ayhan Altintas;Hilmi Volkan Demir;Vakur B. Ertürk; Apparue dans: IEEE Transactions on Microwave Theory and Techniques Date publication: 10.-2017, volume: 65, issue:10, pages: 3733 - 3743 Editeur: IEEE Document complet vers site de l'éditeur
» An Experimental Investigation into the Impact of Vehicular Traffic on Interpersonal Wearable-to-Wearable Communications Channels
 Résumé:In this paper, we have investigated the effects of vehicular traffic on interpersonal wearable-to-wearable (W2W) communications channels in an urban environment at 2.45 GHz. In particular, we have studied the perturbations in the received signal caused by different types of vehicles as they passed through a channel between two persons who maintained various relative orientations while positioned at the opposite sides of a road. As the channel underwent different fading mechanisms depending on whether the vehicle was approaching, transitioning (i.e., intersecting the direct signal path), or receding from the persons, the overall disturbance was appropriately segmented depending on the journey stage. The results have shown that relative body orientation was a significant factor when considering the impact that a vehicle can have on a W2W link. When both persons faced the oncoming traffic, the link was particularly susceptible to significant fading events with variations in the received signal power from the unperturbed state as great as 44.1 dB observed to occur. For all of the journey stages, irrespective of the relative orientation of the persons, the logarithmically transformed long-term fading process was found to be multimodal and well described by a Gaussian mixture model. During the transitioning phase, shadowing caused by the passing automobile obstructing the line-of-sight signal path was found to be the main contributor to the signal fading. However, probably the most remarkable result of the channel characterization work conducted in this paper was the severity of the short-term fading often observed. Such was the intensity of the measured envelope fluctuation in many of the scenarios, we have been able to utilize the recently proposed $\kappa -\mu$ extreme distribution with great success and in the process, provide a further important empirical validation of this new fading model.- Moreover, we have used the resistor-average distance, which is derived from the Kullback–Leibler distance to show the improved fit that the $\kappa -\mu$ extreme distribution offers compared with the $\kappa -\mu$ distribution when used to model the W2W channel in this fading environment. Auteurs: Michael G. Doone;Simon L. Cotton;Claude Oestges; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5418 - 5430 Editeur: IEEE Document complet vers site de l'éditeur
» An Exploratory Study of Word-Scale Graphics in Data-Rich Text Documents
 Résumé:We contribute an investigation of the design and function of word-scale graphics and visualizations embedded in text documents. Word-scale graphics include both data-driven representations such as word-scale visualizations and sparklines, and non-data-driven visual marks. Their design, function, and use has so far received little research attention. We present the results of an open ended exploratory study with nine graphic designers. The study resulted in a rich collection of different types of graphics, data provenance, and relationships between text, graphics, and data. Based on this corpus, we present a systematic overview of word-scale graphic designs, and examine how designers used them. We also discuss the designers’ goals in creating their graphics, and characterize how they used word-scale graphics to visualize data, add emphasis, and create alternative narratives. Building on these examples, we discuss implications for the design of authoring tools for word-scale graphics and visualizations, and explore how new authoring environments could make it easier for designers to integrate them into documents. Auteurs: Pascal Goffin;Jeremy Boy;Wesley Willett;Petra Isenberg; Apparue dans: IEEE Transactions on Visualization and Computer Graphics Date publication: 10.-2017, volume: 23, issue:10, pages: 2275 - 2287 Editeur: IEEE Document complet vers site de l'éditeur
» An FSS Structure Based on Parallel LC Resonators for Multiband Applications
 Résumé:An frequency selective surface (FSS) structure based on parallel LC resonators is proposed to achieve multiband bandpass filtering responses. The parallel LC resonator, implemented by a via-connected metallic line and a parallel-plate capacitor (PPC), serves as the basic element for intentionally constructing FSS unit cell, which exhibits a single-band bandpass filtering response. As a result, the proposed FSS structure can provide a multiband performance by introducing multiple VCMLs and PPCs with different resonance frequencies. Because of the compact resonator resulting from a PPC, the proposed FSSs feature miniaturized unit cell size inherently, for example, the single-band FSS element is as compact as 4.8% of the operating wavelength. Moreover, this kind of FSS structure is also beneficial for independent control of the frequency performance under different polarizations, efficient optimal design of desired resonance frequencies, and easy realization of multiband response with wideband ratio range (e.g., 1.13 to 3.32 for the dual-band FSS). Equivalent circuits of these FSSs are established for explaining the resonating mechanisms and precisely modeling the frequency performances. Finally, prototypes of the dual- and tri-band FSSs are fabricated and measured. The measured results exhibit stable filtering performance under different polarizations and incidence angles (up to 60°). Auteurs: Peng-Chao Zhao;Zhi-Yuan Zong;Wen Wu;Bo Li;Da-Gang Fang; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5257 - 5266 Editeur: IEEE Document complet vers site de l'éditeur
» An hp-adaptive discretization algorithm for signed distance field generation
 Résumé:In this paper we present an $hp$-adaptive algorithm to generate discrete higher-order polynomial Signed Distance Fields (SDFs) on axis-aligned hexahedral grids from manifold polygonal input meshes. Using an orthonormal polynomial basis, we efficiently fit the polynomials to the underlying signed distance function on each cell. The proposed error-driven construction algorithm is globally adaptive and iteratively refines the SDFs using either spatial subdivision ($h$-refinement) following an octree scheme or by cell-wise adaption of the polynomial approximation's degree ($p$-refinement). We further introduce a novel decision criterion based on an error-estimator in order to decide whether to apply $p$- or $h$-refinement. We demonstrate that our method is able to construct more accurate SDFs at significantly lower memory consumption compared to previous approaches. While the cell-wise polynomial approximation will result in highly accurate SDFs, it can not be guaranteed that the piecewise approximation is continuous over cell interfaces. Therefore, we propose an optimization-based post-processing step in order to weakly enforce continuity. Finally, we apply our generated SDFs as colli- ion detector to the physically-based simulation of geometrically highly complex solid objects in order to demonstrate the practical relevance and applicability of our method. Auteurs: Dan Koschier;Crispin Deul;Magnus Brand;Jan Bender; Apparue dans: IEEE Transactions on Visualization and Computer Graphics Date publication: 10.-2017, volume: 23, issue:10, pages: 2208 - 2221 Editeur: IEEE Document complet vers site de l'éditeur
» An Identity-Based Data Aggregation Protocol for the Smart Grid
 Résumé:The smart grid significantly improves the reliability, efficiency, security, and sustainability of electricity services. It plays an important role in modern energy infrastructure. A drawback of this new technique, however, is that the fine-grained metering data may leak private customer information. Thus, various public-key based data aggregation protocols for privacy protection have been proposed. However, the National Institute of Standards and Technology has recommended not using public-key based cryptography in the smart grid, since maintaining the public-key infrastructure is a heavy cost. In this paper, we propose an identity-based data aggregation protocol for the smart grid, which cannot only prevent unauthorized reading and fine-grained analyzing but can also protect against unintentional errors and maliciously altered messages. The basic building block of our protocol is an identity-based encryption and signature scheme in which an identity-based encryption scheme is combined with an identity-based signature scheme. They share the same private/public parameters, which greatly reduces the complexity of the protocol in the smart grid. Security analysis demonstrates the effectiveness of our protocol in the context of six typical attacks against the smart grid. A prototype implementation based on the Intel Edison platform shows that our protocol is efficient enough for physically constrained smart grid operators, such as smart meters. Auteurs: Zhiwei Wang; Apparue dans: IEEE Transactions on Industrial Informatics Date publication: 10.-2017, volume: 13, issue:5, pages: 2428 - 2435 Editeur: IEEE Document complet vers site de l'éditeur
» An Implementation of Hybrid Control Strategy for Distributed Generation System Interface Using Xilinx System Generator
 Résumé:This paper presents an analytical study and hardware-in-loop (HIL) cosimulation design of a grid-connected inverter system with a combinational robust observer-based modified repetitive current controller. In this study, main attention is paid to improve power quality and tracking performance of a distributed generation (DG) interfacing system under various perturbations. The inherent delay in convergence of conventional repetitive controller (RC) is reduced by introducing a low pass filter in delay line and this configuration is named as modified RC (MRC). By adding an observer with MRC, system states can be reconstructed, which improve the system dynamic response. Robust stability and convergence criterion are derived in terms of linear matrix inequality using combined Lyapunov function and singular value decomposition technique, which determine the suitable parameters of feedback control and state observer gains. By utilizing these gains, the switching signals are generated to operate the DG interfacing inverter effectively. The performance of proposed controller is compared with traditional proportional integral, proportional resonant, and MRC under both normal and fault conditions. Finally, HIL cosimulation is performed by realizing the power circuit in MATLAB/Simulink as a simulation model and a control structure using Xilinx system generator platform as burnt in hardware Virtex-6 field programmable gate array (FPGA) ML605 evaluation kit. Auteurs: Smitha Joyce Pinto;Gayadhar Panda;Rangababu Peesapati; Apparue dans: IEEE Transactions on Industrial Informatics Date publication: 10.-2017, volume: 13, issue:5, pages: 2735 - 2745 Editeur: IEEE Document complet vers site de l'éditeur
» An Improved 6-D Pose Detection Method Based on Opposing-Magnet Pair System and Constraint Multiple Magnets Tracking Algorithm
 Résumé:Magnetic tracking method is mainly based on sensing of the magnetic field generated by the magnetic source. Usually a small permanent magnet is used as the magnetic source, and magnetic dipole model is used to estimate the magnetic field. The disadvantage of this approach is that only 5-D pose information can be estimated, but the spin rotation with respect to the direction of magnetic moment cannot be detected. In our previous work, we proposed a novel 6-D (3-D position and 3-D orientation) pose detection method, which was based on an opposing-magnet pair system. The disadvantage is that different rotational parameters may lead to the same pose result due to the symmetric structure of object magnets. In order to solve this problem, we propose an improved 6-D pose detection method in this paper, which is based on a novel constraint multiple magnets tracking algorithm. Two magnets of different sizes with opposite magnetic directions have been combined together to serve as the tracking target. By applying the constraint multi-magnet tracking algorithm, 5-D pose of each magnet can be obtained. Therefore, we can estimate the missing spin rotational information according to the relative movement between these two magnets. Experimental results verified the feasibility of the proposed method. The average position error is 2.3 mm and the orientation error is 4.36°, when the volume ratio between these two magnets is 1:1.5. Auteurs: Shuang Song;Xiaoxiao Qiu;Wei Liu;Max Q.-H. Meng; Apparue dans: IEEE Sensors Journal Date publication: 10.-2017, volume: 17, issue:20, pages: 6752 - 6759 Editeur: IEEE Document complet vers site de l'éditeur
» An Improved Arc Flash Energy Calculation Method and Its Application
 Résumé:In this paper, we describe an improved algorithm for arc flash calculations. This method can be used in any software that performs arc flash calculations to determine the incident energy, arc flash boundaries, and other related parameters for arc flash risk assessment purposes. The method provides a more sophisticated and precise way of calculating short circuit contributions to the fault location. To illustrate the effectiveness of the method, a typical renewable power plant (wind energy) with common types of protection is analyzed. The arc flash risk assessment results are compared in both the conventional way and the presented method. The new approach is called the Integrated Method. This method is an accurate way of modelling the short circuit contribution of the devices, which can potentially change the total short circuit current at the fault location. This Integrated Method considers the decay of the contributing machines and the devices where currents are interrupted due to a protection device. It also accounts for the current decays over time. Auteurs: Afshin Majd;Robert Luo; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 5062 - 5067 Editeur: IEEE Document complet vers site de l'éditeur
» An Improved Delayed Signal Cancellation PLL for Fast Grid Synchronization Under Distorted and Unbalanced Grid Condition
 Résumé:Cascasded delayed signal cancellation (DSC) phase-locked loop (PLL) technique has been attractive for grid synchronization under nonideal grid voltage due to its good harmonics filtering capability. However, it has to face the challenge of slow dynamic response. In this paper, an improved DSC-PLL that features high filtering capability, fast dynamic response and simple structure is presented. This PLL employs only one DSC block and one moving average filter (MAF) block to eliminate all even-order and odd-order harmonics while a second-order phase lead compensator and q-axis feedforward path are introduced to increase the PLL bandwidth. The effect of the phase lead compensator on PLL dynamic performance is analyzed. The feedforward path works only when grid voltage frequency or phase jumps and will not affect the steady state behaviors. Therefore, the PLL can improve the phase estimation accuracy and dynamic speed at the same time even under highly distorted and unbalanced grid voltage. Moreover, linear Lagrange interpolation method is adopted to reduce the discretized errors in the digital implementation of the PLL. The effectiveness of the proposed method is validated by both simulation and experimental results. The comparison results with the existing cascaded DSC-PLL and standard MAF-PLL are also presented. Auteurs: Qicheng Huang;Kaushik Rajashekara; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4985 - 4997 Editeur: IEEE Document complet vers site de l'éditeur
» An Improved Zero-Current-Switching Single-Phase Transformerless PV H6 Inverter With Switching Loss-Free
 Résumé:In this paper, a switching loss-free (SLF) concept for the first six-switches H-bridge inverter (H6-I) topology is proposed. SLF means that its switches are able to operate with soft turn-on and turn-off transitions. In order to implement the SLF goal, a new resonance-trajectory is proposed. Compared with the zero-current-transition H6-I (ZCT-H6-I) topology published in previous literature, the proposed resonance-trajectory can precisely compensate for losses of resonant tanks every switching period. With this intention, an implementing circuit is structured based on the H6-I topology, and its detailed operation principle and performance characteristics are analyzed. As a result, all active switches of the new circuit are switched under zero-current turn-on and zero-current turn-off conditions. Also, the reverse recovery problem of freewheeling diodes is alleviated owing to the zero-current turn-off property of diodes. The SLF target is realized in theory. Finally, experimental results from a 1 kW prototype at 50 kHz switching frequency are provided to verify the effectiveness of the proposed SLF concept in practice. Specifically, the conversion efficiency of the new circuit is over 95% in a wide load range, and there is roughly a 1.5% efficiency improvement compared with the hard-switching H6-I topology. Auteurs: Hua F. Xiao;Li Zhang;Yanqing Li; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7896 - 7905 Editeur: IEEE Document complet vers site de l'éditeur
» An Incremental Learning of Concept Drifts Using Evolving Type-2 Recurrent Fuzzy Neural Networks
 Résumé:The age of online data stream and dynamic environments results in the increasing demand of advanced machine learning techniques to deal with concept drifts in large data streams. Evolving fuzzy systems (EFS) are one of recent initiatives from the fuzzy system community to resolve the issue. Existing EFSs are not robust against data uncertainty, temporal system dynamics, and the absence of system order, because a vast majority of EFSs are designed in the type-1 feedforward network architecture. This paper aims to solve the issue of data uncertainty, temporal behavior, and the absence of system order by developing a novel evolving recurrent fuzzy neural network, called evolving type-2 recurrent fuzzy neural network (eT2RFNN). eT2RFNN is constructed in a new recurrent network architecture, featuring double recurrent layers. The new recurrent network architecture evolves a generalized interval type-2 fuzzy rule, where the rule premise is built upon the interval type-2 multivariate Gaussian function, whereas the rule consequent is crafted by the nonlinear wavelet function. The eT2RFNN adopts a holistic concept of evolving systems, where the fuzzy rule can be automatically generated, pruned, merged, and recalled in the single-pass learning mode. eT2RFNN is capable of coping with the problem of high dimensionality because it is equipped with online feature selection technology. The efficacy of eT2RFNN was experimentally validated using artificial and real-world data streams and compared with prominent learning algorithms. eT2RFNN produced more reliable predictive accuracy, while retaining lower complexity than its counterparts. Auteurs: Mahardhika Pratama;Jie Lu;Edwin Lughofer;Guangquan Zhang;Meng Joo Er; Apparue dans: IEEE Transactions on Fuzzy Systems Date publication: 10.-2017, volume: 25, issue:5, pages: 1175 - 1192 Editeur: IEEE Document complet vers site de l'éditeur
» An Inductive and Capacitive Integrated Coupler and Its LCL Compensation Circuit Design for Wireless Power Transfer
 Résumé:This paper proposes a novel coupler structure for wireless power transfer, which takes advantage of both magnetic and electric fields. The coupler contains four metal structures, two each at the primary and secondary sides, which are capacitively coupled. Each structure consists of long strips of metal sheet to increase its self-inductance, which is then inductively coupled with the other three structures. The structures are vertically arranged and the outer structures are larger than the inner ones to maintain the capacitive couplings. An external LCL compensation network is proposed to resonate with the coupler. The resonance provides conduction currents flowing through each plate to establish magnetic fields and displacement currents flowing between different plates corresponding to electric fields. A 100-W output power prototype is designed and implemented to operate at 1.0 MHz, and it achieves 73.6% efficiency from dc source to dc load across an air-gap distance of 18 mm. The contribution of this paper is to propose a concept to transfer power using magnetic and electric fields simultaneously. Auteurs: Fei Lu;Hua Zhang;Heath Hofmann;Chunting Chris Mi; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4903 - 4913 Editeur: IEEE Document complet vers site de l'éditeur
» An Inductorless Bias-Flip Rectifier for Piezoelectric Energy Harvesting
 Résumé:Piezoelectric vibration energy harvesters have drawn much interest for powering self-sustained electronic devices. Furthermore, the continuous push toward miniaturization and higher levels of integration continues to form key drivers for autonomous sensor systems being developed as parts of the emerging Internet of Things (IoT) paradigm. The synchronized switch harvesting (SSH) on inductor and synchronous electrical charge extraction are two of the most efficient interface circuits for piezoelectric energy harvesters; however, inductors are indispensable components in these interfaces. The required inductor values can be up to 10 mH to achieve high efficiencies, which significantly increase overall system volume, counter to the requirement for miniaturized self-power systems for IoT. An inductorless bias-flip rectifier is proposed in this paper to perform residual charge inversion using capacitors instead of inductors. The voltage flip efficiency goes up to 80% while eight switched capacitors are employed. The proposed SSH on capacitors circuit is designed and fabricated in a 0.35- $\mu \text{m}$ CMOS process. The performance is experimentally measured and it shows a 9.7 $\times$ performance improvement compared with a full-bridge rectifier for the case of a 2.5-V open-circuit zero-peak voltage amplitude generated by the piezoelectric harvester. This performance improvement is higher than most of the reported state-of-the-art inductor-based interface circuits, while the proposed circuit has a significantly smaller overall volume enabling system miniaturization. Auteurs: Sijun Du;Ashwin A. Seshia; Apparue dans: IEEE Journal of Solid-State Circuits Date publication: 10.-2017, volume: 52, issue:10, pages: 2746 - 2757 Editeur: IEEE Document complet vers site de l'éditeur
» An Inertial-Aided Homography-Based Visual Servo Control Approach for (Almost) Fully Actuated Autonomous Underwater Vehicles
 Résumé:A nonlinear inertial-aided image-based visual servo control approach for the stabilization of (almost) fully actuated autonomous underwater vehicles (AUVs) is proposed. It makes use of the homography matrix between two images of a planar scene as feedback information while the system dynamics are exploited in a cascade manner in a control design: An outer-loop control defines a reference setpoint based on the homography matrix and an inner-loop control ensures the stabilization of the setpoint by assigning the thrust and torque controls. Unlike conventional solutions that only consider the system kinematics, the proposed control scheme is novel in considering the full system dynamics (incorporating all degrees of freedom, nonlinearities, and couplings, as well as interactions with the surrounding fluid) and in not requiring information of the relative depth and normal vector of the observed scene. Augmented with integral corrections, the proposed controller is robust with respect to model uncertainties and disturbances. The almost global asymptotic stability of the closed-loop system is demonstrated, which is the largest domain of attraction one can achieve by means of continuous feedback control. Simulation results illustrating these properties on a realistic AUV model subjected to a sea current are presented and finally experimental results on a real AUV are reported. Auteurs: Szymon Krupínski;Guillaume Allibert;Minh-Duc Hua;Tarek Hamel; Apparue dans: IEEE Transactions on Robotics Date publication: 10.-2017, volume: 33, issue:5, pages: 1041 - 1060 Editeur: IEEE Document complet vers site de l'éditeur
» An Information Theory-Based Scheme for Efficient Classification of Remote Sensing Data
 Résumé:Information theory has recently become an interesting topic in earth observation data management and analysis, since it can provide important information on hidden interactions and correlations among the considered data records. Although several methods have been proposed and implemented to efficiently extract a proper set of features and deliver accurate image investigation, classification, and segmentation, these architectures show drawbacks when the data sets are characterized by complex interactions among the samples. In this paper, a new approach based on information theory for automatic pattern recognition is introduced for accurate classification of remotely sensed data. Experimental results carried out on real data sets show the validity of the proposed approach. Auteurs: Andrea Marinoni;Gianni Cristian Iannelli;Paolo Gamba; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5864 - 5876 Editeur: IEEE Document complet vers site de l'éditeur
» An Input–Output Framework for Submanifold Stabilization
 Résumé:We study submanifold stabilization problems from an input–output perspective, where plant and controller are relations on their sets of input–output signals. In contrast to the classical input–output approaches, we consider signals whose integral $p$-fold distance to a submanifold is finite. For feedback interconnections of relations on such signals, we develop a framework to show that the distance of the output of the plant to the desired submanifold remains bounded. Within this framework, we present a small-gain theorem, a feedback theorem for conic relations, and a feedback theorem for passive relations. We connect our findings to multiplier theory and present applications to synchronization and pattern generation. Auteurs: Jan Maximilian Montenbruck;Murat Arcak;Frank Allgöwer; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5170 - 5184 Editeur: IEEE Document complet vers site de l'éditeur
» An Interactive Fuzzy Physical Programming for Solving Multiobjective Skip Entry Problem
 Résumé:The multicriteria trajectory planning for space manoeuvre vehicle (SMV) is recognized as a challenging problem. Because of the nonlinearity and uncertainty in the dynamic model and even the objectives, it is hard for decision makers to balance all of the preference indices without violating strict path and box constraints. In this paper, to provide the designer an effective method and solve the trajectory hopping problem, an interactive fuzzy physical programming algorithm is introduced. A new multiobjective SMV optimal control problem is formulated and parameterized using an adaptive technique. By using the density function, the oscillations of the trajectory can be captured effectively. In addition, an interactive decision-making strategy is applied to modify the current designer's preferences during optimization process. Two realistic decision-making scenarios are conducted by using the proposed algorithm; Simulation results indicated that without driving objective functions out of the tolerable region, the proposed approach can have better performance in terms of the satisfactory degree compared with other approaches like traditional weighted-sum method, goal programming and fuzzy goal programming. Also, the results can satisfy the current preferences given by the decision makers. Therefore, the method is potentially feasible for solving multicriteria SMV trajectory planning problems. Auteurs: Runqi Chai;Al Savvaris;Antonios Tsourdos;Yuanqing Xia; Apparue dans: IEEE Transactions on Aerospace and Electronic Systems Date publication: 10.-2017, volume: 53, issue:5, pages: 2385 - 2398 Editeur: IEEE Document complet vers site de l'éditeur
» An Introduction to Goodness of Fit for PMU Parameter Estimation
 Résumé:It is posited that the process of measuring the various parameters that characterize a signal is equivalent to a fitting problem in mathematics. The equation being fit is a model based on the “physics” of the signal. The Fourier transform or rms calculations in a phasor measurement unit (PMU) furnish the values of the coefficients. Regardless of exactly how the measurement is made, a metric we define and call the goodness of fit allows the measuring system to comment on the match between the signal it is observing and the model. The metric is based on the residuals, the differences between the signal itself and the value calculated from the result of measurement. Results from real-word PMUs and real-world signals illustrate that the equation of the PMU is well solved during steady conditions. We examine the effect of a fault in the transmission system on the goodness-of-fit metric for a PMU. We also apply the metric to results from a microPMU in the distribution system. Auteurs: Artis Riepnieks;Harold Kirkham; Apparue dans: IEEE Transactions on Power Delivery Date publication: 10.-2017, volume: 32, issue:5, pages: 2238 - 2245 Editeur: IEEE Document complet vers site de l'éditeur
» An Investigation of Discharge Characteristics of an Electrothermal Pulsed Plasma Thruster
 Résumé:The capillary-based pulsed plasma thruster (PPT) has high-energy transfer efficiency, which provides potential to improve traditional PPT performance. In this paper, the discharge characteristics of a capillary-based PPT have been investigated. First, the typical process of voltage and current waveform is recognized. It is featured with a fast voltage drop (~25 ns) and a consequent damped sine wave oscillation discharge. Then based on the circuit analysis, the equivalent plasma resistance has been calculated. The current waveform is well fit with a linearly increasing resistance model. The influence of charging voltage has also been studied. The deposited energy increases while the transfer efficiency decreases with the increasing applied voltage. The cavity dimension has effects on the equivalent circuit parameters. The results show that longer cavity and smaller diameter lead to more deposited energy and higher transfer efficiency. The influence of voltage and capillary dimension on the mass shot characteristic has been discussed. Finally, the estimated impulse bit has been calculated and the impulse bit characteristics have been discussed. These results can contribute to the further optimization of PPT. Auteurs: Yanan Wang;Weidong Ding;Le Cheng;Jiaqi Yan;Zhichuang Li;Jiachen Wang;Yongsheng Wang; Apparue dans: IEEE Transactions on Plasma Science Date publication: 10.-2017, volume: 45, issue:10, pages: 2715 - 2724 Editeur: IEEE Document complet vers site de l'éditeur
» An LC-Compensated Electric Field Repeater for Long-Distance Capacitive Power Transfer
 Résumé:This paper proposes an LC-compensated electric field repeater to extend the transfer distance of a capacitive power transfer (CPT) system. The repeater contains two metal plates connected with an external capacitor and an external inductor. The plates are used to generate electric fields to transfer power. The external inductor and capacitor are used to resonate with the plates in order to increase the voltage levels. The repeater is placed between a transmitter and a receiver, which also contains metal plates compensated by an LC network. The repeater can increase the transfer distance of the CPT system without significantly influencing the system power and efficiency. In this paper, the capacitive coupler structure and dimensions are designed and simulated using Maxwell software. Considering all the capacitive coupling between plates, an equivalent circuit model is derived. The fundamental harmonics approximation method is used to analyze the working principle of the circuit. A 150 W input power CPT system is designed as an example to validate the proposed repeater structure and compensation circuit topology. The system can achieve an efficiency of 66.9% from dc source to dc load, when the transfer distance is 360 mm and the repeater is placed between the transmitter and the receiver. Auteurs: Hua Zhang;Fei Lu;Heath Hofmann;Weiguo Liu;Chunting Chris Mi; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4914 - 4922 Editeur: IEEE Document complet vers site de l'éditeur
» An Online Monitoring System for Oil Immersed Power Transformer Based on SnO2 GC Detector With a New Quantification Approach
 Résumé:In this paper, an online monitoring system based on a SnO2 gas chromatographic detector for power transformer condition assessment is developed. For a quantitative analysis of feature gases dissolved in transformer oil, a mathematical model derived from the chemistry and semiconductor theory is proposed. On the basis of this, gas chromatography measurement module along with electronic controlling and data sampling system is designed and integrated. A series of repeatability test and quantitative analysis has been performed; the repeatability performance is excellent for given concentrations; the measurement accuracy based on the proposed mathematical model for the feature gases shows good suitability. Furthermore, the transformer diagnosis is performed for identifying fault types. The experimental and practical application results demonstrate the effectiveness of this system. Auteurs: Jingmin Fan;Feng Wang;Qiuqin Sun;Feng Bin;Huisheng Ye;Yuhan Liu; Apparue dans: IEEE Sensors Journal Date publication: 10.-2017, volume: 17, issue:20, pages: 6662 - 6671 Editeur: IEEE Document complet vers site de l'éditeur
» An Online Scalable Approach to Unified Multirobot Cooperative Localization and Object Tracking
 Résumé:In this paper, we present a unified approach for multi-robot cooperative simultaneous localization and object tracking based on particle filters. Our approach is scalable with respect to the number of robots in the team. We introduce a method that reduces, from an exponential to a linear growth, the space and computation time requirements with respect to the number of robots in order to maintain a given level of accuracy in the full-state estimation. Our method requires no increase in the number of particles with respect to the number of robots. However, in our method, each particle represents a full-state hypothesis, leading to the linear dependency on the number of robots of both space and time complexity. The derivation of the algorithm implementing our approach from a standard particle filter algorithm and its complexity analysis are presented. Through an extensive set of simulation experiments on a large number of randomized datasets, we demonstrate the correctness and efficacy of our approach. Through real robot experiments on a standardized open dataset of a team of four soccer-playing robots tracking a ball, we evaluate our method's estimation accuracy with respect to the ground truth values. Through comparisons with other methods based on 1) nonlinear least squares minimization and 2) joint extended Kalman filter, we further highlight our method's advantages. Finally, we also present a robustness test for our approach by evaluating it under scenarios of communication and vision failure in teammate robots. Auteurs: Aamir Ahmad;Guilherme Lawless;Pedro Lima; Apparue dans: IEEE Transactions on Robotics Date publication: 10.-2017, volume: 33, issue:5, pages: 1184 - 1199 Editeur: IEEE Document complet vers site de l'éditeur
» An Overlay Architecture for Throughput Optimal Multipath Routing
 Résumé:Legacy networks are often designed to operate with simple single-path routing, like the shortest path, which is known to be throughput suboptimal. On the other hand, previously proposed throughput optimal policies (i.e., backpressure) require every device in the network to make dynamic routing decisions. In this paper, we study an overlay architecture for dynamic routing, such that only a subset of devices (overlay nodes) need to make the dynamic routing decisions. We determine the essential collection of nodes that must bifurcate traffic for achieving the maximum multi-commodity network throughput. We apply our optimal node placement algorithm to several graphs and the results show that a small fraction of overlay nodes is sufficient for achieving maximum throughput. Finally, we propose a threshold-based policy (BP-T) and a heuristic policy (OBP), which dynamically control traffic bifurcations at overlay nodes. Policy BP-T is proved to maximize throughput for the case when underlay paths do no overlap. In all studied simulation scenarios, OBP not only achieves full throughput but also reduces delay in comparison to the throughput optimal backpressure routing. Auteurs: Nathaniel M. Jones;Georgios S. Paschos;Brooke Shrader;Eytan Modiano; Apparue dans: IEEE/ACM Transactions on Networking Date publication: 10.-2017, volume: 25, issue:5, pages: 2615 - 2628 Editeur: IEEE Document complet vers site de l'éditeur
» An Ultralow Power Time-Domain Temperature Sensor With Time-Domain Delta–Sigma TDC
 Résumé:Without using bipolar transistors, serially connected inverter cells generate clock delay according to temperature. The delay is compared with a reference clock to estimate the temperature. The proposed time-to-digital converter (TDC) structure is using a time-domain delta–sigma $(\Delta\Sigma)$ modulator. This type of TDC with $\Delta\Sigma$ modulator can achieve higher resolution by increasing the oversampling ratio, with the advantages of low area and low power consumption. To increase the accuracy by producing true temperature-independent time delay, an external reference clock is utilized, instead of temperature-independent inverter cells, for robust operations. The measured temperature sensors demonstrated a minimum power consumption of 480 nW and a resolution under 0.1 °C. The $3\sigma$ error of the sensor is ±0.99 °C over −20 °C–80 °C temperature range from ten-sample measurement results. The chip area is 0.089 mm2 using a Dongbu 0.18-$\mu\mbox{m}$ CMOS process. The conversion rate is 1.25 samples/s. Auteurs: Wonjong Song;Junan Lee;Nayeon Cho;Jinwook Burm; Apparue dans: IEEE Transactions on Circuits and Systems II: Express Briefs Date publication: 10.-2017, volume: 64, issue:10, pages: 1117 - 1121 Editeur: IEEE Document complet vers site de l'éditeur
» An Ultrawideband Conformal Capsule Antenna With Stable Impedance Matching
 Résumé:An ultrawideband conformal capsule slot antenna, which has a simple configuration and a stable impedance matching characteristic, is described in this paper. In the past, wideband outer-wall antennas have been proposed for capsule-type applications. However, this paper shows that the outer wall is not a good choice for placing capsule antennas, since such a choice exhibits a high specific absorption ratio, low gain, and low efficiency. Instead, the antenna proposed in this paper is conformal to the inner wall of a capsule shell, and it provides a wide impedance bandwidth ranging from 1.64 to 5.95 GHz (113.6%). Furthermore, the impedance matching remains stable even with a change in the operating environment. Since in a typical application scenario a capsule will move through the digestive system, and thus experience varying environments, a wide bandwidth and stable performance are both very desirable attributes of the antenna, whose design is discussed in this paper. Moreover, the proposed antenna continues to maintain a stable impedance match even when a battery is added inside the capsule, or when there is a change in the battery size and/or its position. Given these advantages, we argue that slot antennas are well suited for incorporation into capsule antennas for the present application. Auteurs: Zengdi Bao;Yong-Xin Guo;Raj Mittra; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5086 - 5094 Editeur: IEEE Document complet vers site de l'éditeur
» Analog Bloom Filter and Contention-Free Multi-Bit Simultaneous Query for Centralized Wireless Networks
 Résumé:In this paper, novel simultaneous query techniques are proposed for wireless networks, which allow the access point (AP) of the network to gather key control information from active nodes in the network at low overhead. The query techniques are based on OFDM, and include the analog bloom filter (ABF), with which active nodes send signals simultaneously on randomly selected subcarriers to inform the AP about their identities, as well as the collision-free multi-bit (CFM) query, with which nodes send signals simultaneously on non-overlapping subcarriers to inform the AP about their queue lengths. Both the ABF and CFM queries require just one OFDM symbol as the response, and therefore incur very low overhead. Based on ABF and CFM, a simple medium access control (MAC) protocol, called Muqmac, is also proposed, with which the AP can obtain the queue states of the nodes and schedule data transmissions in a centralized manner. ABF and CFM are first evaluated with the 802.11n channel model and are shown to achieve desirable performance. Both ABF and CFM, as well as Muqmac, are also implemented on the Microsoft Sora software-defined radio. The experimental results show that after removing some obvious overhead specific to the testbed, the MAC layer throughput of Muqmac is over 75% of the physical layer data rate even under very challenging traffic conditions. Auteurs: Zhenghao Zhang; Apparue dans: IEEE/ACM Transactions on Networking Date publication: 10.-2017, volume: 25, issue:5, pages: 2916 - 2929 Editeur: IEEE Document complet vers site de l'éditeur
» Analog Coded SoftCast: A Network Slice Design for Multimedia Broadcast/Multicast
 Résumé:This paper presents a network slice design for ultra high definition (UHD) video broadcast/multicast to achieve higher network efficiency and improved quality of experience (QoE). The proposed network slice design consists of a rateless source compression scheme and an analog-coded SoftCast scheme. The rateless Spinal code is adopted to compress the video source at content server and the compressed source is transmitted from content server across wireless core network to the base station. An a priori information-assisted Spinal decoder is designed to utilize the sparsity of bit planes for compression. In the analog-coded SoftCast scheme, we design a new chaotic function-based analog code with negligible power penalty for the generalized Gaussian-distributed source in SoftCast because the existing chaotic functions designed for uniformly distributed sources suffer from serious power penalty in SoftCast. We also design a maximum a posteriori probability decoding algorithm for the proposed analog code in order to exploit the statistics of video source as a priori information to improve the performance. The experimental results show that the proposed rateless code-based compression scheme achieves efficient compression and approaches the bound of binary erasure channel. In particular, the 1/2 analog-coded SoftCast has almost 2 dB gain over conventional SoftCast with two repetitions, and the 1/3 analog-coded SoftCast has almost 3 dB gain over conventional SoftCast with three repetitions. The system simulations for the broadcast system show higher network capacity and improved QoE in the proposed UHD slice, because the reconstructed video quality of each user is commensurate with its channel condition. Auteurs: Bin Tan;Jun Wu;Ying Li;Hao Cui;Wei Yu;Chang Wen Chen; Apparue dans: IEEE Transactions on Multimedia Date publication: 10.-2017, volume: 19, issue:10, pages: 2293 - 2306 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis and Design of Bang-Bang PD-Based Phase Noise Filter
 Résumé:In this paper, we present a bang-bang phase detector (BBPD) and a delay-line frequency discriminator-based phase noise filter (PNF). With a larger phase detection gain, the BBPD-based PNF enhances the sensitivity by suppressing the charge pump noise. A time-amplifier and a five times voting machine are introduced together with the sense-amplifier-flip-flop to minimize the BBPD noise to make its effects negligible in the PNF sensitivity. At 1-MHz offset, the PNF demonstrates 15-dB phase noise suppression with −120.2-dBc/Hz sensitivity. Its phase noise suppression offset frequency is from 100 kHz to 8 MHz with 10–10.1-GHz input frequency range. The circuit is fabricated in a 65-nm CMOS technology, and dissipates 98-mW power. Auteurs: Tongning Hu;Shilei Hao;Qun Jane Gu; Apparue dans: IEEE Transactions on Circuits and Systems I: Regular Papers Date publication: 10.-2017, volume: 64, issue:10, pages: 2703 - 2713 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis and Design of Closed-Loop Control of Electrolytic Capacitor-Less Six-Pulse DC Link Three-Phase Inverter
 Résumé:Three-phase inverters in uninterrupted power supply, electric vehicles, and hybrid electric vehicles use an intermediate dc-link electrolytic capacitor, which has reliability issues and is one prominent cause of inverter failure and limited life. The large volume of an electrolytic capacitor increases the size and cost of the system. Recent research on electrolytic capacitorless inverters using six-pulse modulation technique along with high-frequency power conversion has attempted to address this issue. However, closed-loop operation and control has some issues due to capacitorless dc-link. In this paper, closed-loop operation, design, and implementation of an electrolytic capacitorless inverter is presented. A proof-of-concept 1-kW hardware prototype has been built and tested in a laboratory under different loading conditions. In total, 98% rated efficiency of the inverter is obtained with total harmonic distortion within 2%. Transient results during start-up and load change are smooth, demonstrating safe operation of the inverter. Auteurs: Anirban Ghoshal;Xuewei Pan;Akshay K Rathore; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4957 - 4964 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis and Design of the Ladder Resonant Switched-Capacitor Converters for Regulated Output Voltage Applications
 Résumé:The traditional Ladder switched-capacitor converters have the issues of hard-switching operation and poor line regulation capability. By adding a resonant inductor and substituting a bulky capacitor bank with a small resonant capacitor, its resonant configuration can be obtained and the aforementioned issues could be solved. In addition, by operating the Ladder resonant switched-capacitor converters (RSCs) above the resonance, the optimized operation region is found and some transformational changes can be obtained: the transistors can be operated with zero voltage switching turn-on and diodes are zero current switching turned on/off; the line regulation range is increased significantly for regulated output voltage applications; the instability issue of transition between discontinuous current mode and continuous current mode can be avoided with closed loop; and the voltage/current stress of the resonant tank is reduced. Extensive analysis above and below the resonance is presented to reveal the converter operation modes, voltage-gain curves, output characteristics, and voltage/current stress of the resonant tank. A 3X Ladder RSC prototype for an electronic fuel injection application with maximum output voltage 150 V, maximum power 140 W and peak efficiency 97.6% was designed to be operating in the optimized operation region. The analysis is verified by experimental results. Auteurs: Shouxiang Li;Kang Xiangli;Yifei Zheng;Keyue Ma Smedley; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7769 - 7779 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis of a Direct Antenna Modulation Transmitter for Wideband OOK With a Narrowband Antenna
 Résumé:The characteristics of a narrowband antenna transmitting a broadband on–off-keyed signal using direct antenna modulation (DAM) are studied. The DAM technique has previously been proposed to generate a broadband signal using a rapidly time-varying antenna, but the signals produced using this technique and its limitations are not well understood. In this paper, we quantitatively compare the performance of a DAM transmitter to a conventional time-invariant transmit antenna. We show that the fall time of an RF pulse produced with the DAM configuration is measurably shorter than with the conventional system; however, the pulse rise time using both systems is identical. The performance of each system is then analyzed in terms of the bit error rate over a simple point-to-point link using analytical models, numerical simulation, and measurement. DAM reduces the intersymbol interference (ISI) by reducing the discharging time; however, the overall performance remains similar to the conventional system because of their similar charging times. While the DAM configuration does radiate a qualitatively broader spectrum as observed in previous studies, this does not translate into quantitative improvement in the characteristics of a transmitted data signal. Auteurs: Shruti Srivastava;Jacob J. Adams; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 4971 - 4979 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis of Distribution Using Graphical Goodness of Fit for Airborne SAR Sea-Clutter Data
 Résumé:For radar target detection, the clutter distribution model needs to be identified first. The goodness of fit (GoF) between the original data and the assumed distribution can be used to choose the proper distribution model. Generally, the GoF is obtained using data histogram and theoretical distribution curve, and then the distribution model is judged via GoF. However, when the sample number is small, the histogram is rough and fluctuating, affecting the analysis of GoF. For the small sample, the graphical characteristic is obtained with the sample data to choose the most fitting distribution to the data in this paper. The graphical characteristic is acquired by a simpler process, that is, the original data are directly set as the test statistics, avoiding computing and sorting of other statistics. In this paper, the real airborne circular synthetic aperture radar data under different scan angles are analyzed using the GoF corresponding to histogram and graphical GoF, respectively. The results show that when the sea-clutter data histogram is close to two distributions, a more fitting distribution model may not be obtained by traditional GoF, but can be acquired by graphical representation. In addition, the sea data with different sight angles have different match properties. It is seen that the sea data are closer to the Rayleigh distribution in side-looking mode than that in big squint-angle mode, while the Weibull distribution and K distribution show equal fitting performance to sea clutter under variant radar sight angles. Auteurs: Zhihui Xin;Guisheng Liao;Zhiwei Yang;Yuhong Zhang;Hongxing Dang; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5719 - 5728 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis of Leakage Loss in Silicon Photonics with Finite Gain Compensation
 Résumé:Silicon waveguides fabricated on silicon-on-insulator wafers are leaky in nature. This fact puts a lower bound on the insulator thickness in silicon photonic structures as integrated with compact electronic devices. We examine this constraint from the angle of finite gain compensation for leakage loss using III-V semiconductor gain media bonded to passive silicon waveguides. With a reasonable magnitude of available gain, we find that an insulator layer thinner than 320 nm could support the fundamental quasi-transverse-electric mode of silicon waveguides with a core thickness around 170 nm. This may enable the integration of photonic devices with compact electronic counterparts for radio-frequency and analog applications. Furthermore. size reductions to the level of partially depleted electronic devices might be possible if the leakage loss need not be fully compensated, or the gain limit could be raised Auteurs: Po-Jui Chiang;Tien-Tsorng Shih; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 10 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis of Multi-Server Queue With Spatial Generation and Location-Dependent Service Rate of Customers as a Cell Operation Model
 Résumé:A novel multi-server queue with heterogeneous customers is formulated and analyzed as the model of operation of a cell of a mobile communication network. We assume that the cell is divided into zones depending on signal quality. The type of a customer corresponds to a zone in which this customer is currently situated and the rate of the customer’s service depends on his/her type. During service, the customer may transit to another zone or terminate service (e.g., owing to poor service quality or departure from the cell). The stationary distribution of the system states and the key performance measures of the system are computed. Numerical results are presented. Auteurs: Sergei Dudin;Chesoong Kim; Apparue dans: IEEE Transactions on Communications Date publication: 10.-2017, volume: 65, issue:10, pages: 4325 - 4333 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis of Path-Length Effects in Multiloop Cross-Eye Jamming
 Résumé:The effect of path-length differences on multiloop retrodirective cross-eye jammers is evaluated. It is shown that such jammers may act as beacons, and the conditions under which this occurs are investigated for two-loop jammers. The sensitivity of the two-loop cross-eye gain to path-length differences is also studied and is found to be small for small path-length differences, but to increase rapidly. The effect of the two-loop cross-eye jammer parameters on path-length effects is also considered. Auteurs: Warren Paul du Plessis; Apparue dans: IEEE Transactions on Aerospace and Electronic Systems Date publication: 10.-2017, volume: 53, issue:5, pages: 2266 - 2276 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis of Performance Optimization for a Microwave Photonic Filter Based on Stimulated Brillouin Scattering
 Résumé:A single passband microwave photonic filter (MPF) based on stimulated Brillouin scattering (SBS) is analyzed and experimentally demonstrated. The proposed MPF can be tuned over a dramatically large frequency range, which overcomes the disadvantage in previously reported schemes based on SBS that the frequency tuning range is limited within two folds of the Brillouin frequency shift. The single passband MPF is obtained by enhancing the amplitude of the microwave passband generated by SBS gain while suppressing the amplitude of the microwave passband generated by SBS loss through optimizing the key parameters of the SBS process, including the pump power, the length of high nonlinear fiber, and the polarization states of the pump and signal waves. A theoretical model is established to describe the operation principle of the SBS-based MPF and illustrate the mechanism for the single passband, and an experiment is carried out to verify the theoretical analysis. In the experiment, the central frequency of the single passband MPF can be tuned from 0 to 40 GHz, which is only limited by the bandwidth of the adopted electro-optic modulator and photodetector. The main to secondary sidelobe ratio can reach 55 dB and the full width at half-maximum bandwidth is 16 MHz. The achieved MPF is specifically suitable for applications in ultrahigh selective filtering. Auteurs: Haitao Tang;Yuan Yu;Chi Zhang;Ziwei Wang;Lu Xu;Xinliang Zhang; Apparue dans: Journal of Lightwave Technology Date publication: 10.-2017, volume: 35, issue:20, pages: 4375 - 4383 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis of PM Transverse-Flux Outer Rotor Machines With Different Configuration
 Résumé:This paper presents the electromagnetic analysis of two permanent magnet transverse-flux outer rotor machines with and without magnetic shunts. The research started with designing and analyzing a permanent magnet transverse-flux machine with an inner rotor, previously patented by J. Giearas in 2010. However, the results obtained from the prototype test differed significantly from the estimated results. Applying three-dimensional (3-D) finite element method (FEM), the main problem of the machine was detected. The problem was in high flux leakage that weakened magnetic flux density in the stator poles. Such observation led to designing two machines with outer rotor, with and without magnetic shunts. The role of the magnetic shunts is to minimize flux leakage in the stator in order to improve the performance of the machine. Electromechanical parameters of both outer rotor machines, with and without magnetic shunts, are compared in the paper. Three-D FEM results are supported by laboratory analysis of the machines’ prototypes. Experimental measurements proved that the machine with magnetic shunts demonstrated better performance as compared with the machine without magnetic shunts. Presence of the magnetic shunts in the machine resulted in reducing of flux leakage and cogging torque. Auteurs: Oleksandr Dobzhanskyi;Rupert Gouws;Ebrahim Amiri; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4260 - 4268 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis of Temperature Effects on Performance of Interior Permanent Magnet Machines for High Variable Temperature Applications
 Résumé:The purpose of this paper is to analyze and investigate the influence of temperature variation on the characteristics and performance of interior permanent magnet (IPM) machines. The impact of temperature variation on the materials of IPM machines is discussed to show the sources of performance variation. The flux linkages, torque output capability, and inductance variation as functions of the temperature are analyzed and discussed. This paper also shows the influence of temperature variation on key IPM machines performance including constant torque curves, voltage limit ellipses, maximum torque per ampere trajectories, and torque–speed curves. Experimental results of a traction IPM machine verified the analysis and theory. The results and trends shown in this paper set a foundation for developing control algorithm, which takes the temperature effects into consideration, especially in the applications where operating temperature varies significantly. Auteurs: Silong Li;Bulent Sarlioglu;Sinisa Jurkovic;Nitin R. Patel;Peter Savagian; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4923 - 4933 Editeur: IEEE Document complet vers site de l'éditeur
» Analysis on the Rapid Recovery of Irradiated VDMOSFETs by the Positive High Electric Field Stress
 Résumé:High electric field stress (HEFS) and annealing effects on irradiated (by 60Co $gamma$ -ray) vertical double-diffused MOSFETs (VDMOSFETs) are investigated. The behaviors of the oxide-trapped charges and interface traps during the stress are measured by using a simplified midgap technique. Rapid recovery of the threshold voltage ( $V_{mathrm {th}}$ ) for the irradiated VDMOSFET is observed under a positive high electric field stress (PHEFS). The results show that the densities of oxide-trapped charges and interface traps decreased more rapidly for the PHEFS than that for postirradiation annealing. Repeated irradiation results of PHEFS-recovered VDMOSFETs indicate the possibility of reusing the irradiated VDMOSFETs. Auteurs: Ling Peng;Dongqing Hu;Yunpeng Jia;Yu Wu;Pengzhen An;Guo Jia; Apparue dans: IEEE Transactions on Nuclear Science Date publication: 10.-2017, volume: 64, issue:10, pages: 2633 - 2638 Editeur: IEEE Document complet vers site de l'éditeur
» Analytical Formulas for Artificial Dielectrics With Nonaligned Layers
 Résumé:In this paper, we present analytical models to describe artificial dielectric layers (ADLs), when a lateral shift between layers is present. The alternate lateral displacement between layers is an important parameter to engineer the desired effective electromagnetic properties of the equivalent homogeneous material realized with the ADLs. More specifically, the equivalent dielectric constants that can be realized by alternatively shifting the layers are higher compared with the aligned case. Closed-form expressions are derived for the equivalent layer reactance that includes the higher order interaction between shifted layers. The given analytical formulas can be used to derive an equivalent circuit model that describes the scattering parameters of a plane wave impinging on a slab composed by an arbitrary finite number of metal layers. To aid the design of artificial dielectric slabs, the effective permittivity and permeability tensors are also retrieved from the scattering parameters. Auteurs: Daniele Cavallo;Cantika Felita; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5303 - 5311 Editeur: IEEE Document complet vers site de l'éditeur
» Analytical Insights Into Parameter Estimation for Wiener Deconvolution
 Résumé:All real-time signals observed from various measurement systems require signal-processing techniques like the deconvolution, to compensate for the effect of transfer function of the systems. Wiener deconvolution is a widely used signal-processing technique for signal restoration. Often, if the power spectral density of signal and noise is unknown, the accuracy of the restored signal depends on an unknown filter parameter. In the literature, time-consuming, iterative, computational methods were reported to estimate the parameter. However, many of these methods give a range of optimum values instead of an unique value and often lead to either over-smoothing or under-smoothing. In this paper, novel analytical expressions are presented through which the unknown parameter can be estimated explicitly. The analytical results of this study are compared with the numerical methods, and they are found to be accurate and robust against numerical evaluation. Further, the results are demonstrated for signals obtained experimentally from the pulsed electroacoustic system and a network, in authors’ laboratory. Auteurs: Ashish Gupta;Chandupatla Chakradhar Reddy; Apparue dans: IEEE Transactions on Instrumentation and Measurement Date publication: 10.-2017, volume: 66, issue:10, pages: 2566 - 2575 Editeur: IEEE Document complet vers site de l'éditeur
» Analytical Modeling of Mutually Coupled Switched Reluctance Machines Under Saturation Based on Design Geometry
 Résumé:An analytical calculation of the winding flux linkages and torque is proposed for fully pitched mutual coupled switched reluctance motors to develop a machine model without using numerical methods. The proposed technique is not empirical and does not require any finite-element analysis (FEA). The design parameters and the material properties of the machine are the only inputs to the model, which can predict the winding flux linkages and torque at any phase currents and rotor positions. The model is applicable for the rotor positions where the stator and rotor poles overlap. Initial assumptions and then the step-by-step procedure for flux linkage, co-energy, and torque calculations are provided. The flux linkages and torque predicted through the proposed modeling technique are compared with the FEA results. Finally, experimental results of flux linkage and torque are provided to verify the accuracy of the proposed modeling technique. Auteurs: Wasi Uddin;Yilmaz Sozer; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4431 - 4440 Editeur: IEEE Document complet vers site de l'éditeur
» Analyzing Graphene-Based Absorber by Using the WCS-FDTD Method
 Résumé:A weakly conditionally stable finite-difference time-domain (WCS-FDTD) method is used to simulate a graphene-based absorber. By using the auxiliary differential equation and Padé fitting method, both the interband and intraband conductivities of the graphene are incorporated into the WCS-FDTD method. The time step increment in the proposed method is not determined by the fine meshes in the graphene layer, so the computational efficiency of this method is greatly improved from that of the conventional FDTD method. By using the proposed WCS-FDTD method, a graphene-based absorber is simulated and analyzed. The numerical result shows that the graphene can achieve tunable absorption through controlling its chemical potential, and the interband conductivity of the graphene has important effects on the performance of the absorber. Auteurs: Juan Chen;Jianxing Li;Qing Huo Liu; Apparue dans: IEEE Transactions on Microwave Theory and Techniques Date publication: 10.-2017, volume: 65, issue:10, pages: 3689 - 3696 Editeur: IEEE Document complet vers site de l'éditeur
» Analyzing the Stability of Switched Systems Using Common Zeroing-Output Systems
 Résumé:This paper introduces the notion of common zeroing-output systems (CZOS) to analyze the stability of switched systems. The concept of CZOS allows one to verify weak zero-state detectability. It characterizes a common behavior of any individual subsystem when the output signal for each subsystem is “approaching” zero. Heuristically speaking, it removes the effect of switching behavior, and thus enables one to analyze stability properties in systems with complex switching signals. With the help of CZOS, the Krasovskii–LaSalle theorem can be extended to switched nonlinear time-varying systems with both arbitrary switching and more general restricted switching cases. For switched nonlinear time-invariant systems, the needed detectability condition is further simplified, leading to several new stability results. Particularly, when a switched linear time-invariant system is considered, it is possible to generate a recursive method, which combines a Krasovskii–LaSalle result and a nested Matrosov result, to find a CZOS if it exists. The power of the proposed CZOS is demonstrated by consensus problems in literature to obtain a stronger convergence result with weaker conditions. Auteurs: Ti-Chung Lee;Ying Tan;Iven Mareels; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5138 - 5153 Editeur: IEEE Document complet vers site de l'éditeur
» Angle Domain Hybrid Precoding and Channel Tracking for Millimeter Wave Massive MIMO Systems
 Résumé:The millimeter-wave (mm-wave) massive multiple-input multiple-output (MIMO) system has gained much attention for its considerable improvement in system throughput. However, the cost of complex hardware, e.g., radio frequency (RF) chains, hinders it from practical deployment. In this paper, we propose an angle domain hybrid precoding and channel tracking method by exploring the spatial features of the mm-wave massive MIMO channel. The number of the effective spatial beams, or equivalently the RF chains, is enormously decreased via the operation of spatial rotation. The users are then scheduled by the angle division multiple access scheme, which groups users according to their direction of arrivals (DOAs). Meanwhile, a channel tracking method is designed for the subsequent data transmission through a small number of pilot symbols. Specifically, the channel information is divided into the DOA information and the gain information, where the DOA information is tracked by a modified unscented Kalman filter and the gain information is estimated from beam training. Numerical results are provided to corroborate our studies. Auteurs: Jianwei Zhao;Feifei Gao;Weimin Jia;Shun Zhang;Shi Jin;Hai Lin; Apparue dans: IEEE Transactions on Wireless Communications Date publication: 10.-2017, volume: 16, issue:10, pages: 6868 - 6880 Editeur: IEEE Document complet vers site de l'éditeur
» Angle-of-Arrival Estimation of Broadband Microwave Signals Based on Microwave Photonic Filtering
 Résumé:We propose and experimentally demonstrate a photonic approach to estimate the angle-of-arrival (AOA) of broadband microwave signals. Using an integrated polarization-division multiplexing Mach–Zehnder modulator and a differential group-delay module, a microwave photonic notch filter is constructed. The relative time delay in reception of the signal at two separate antenna elements can be obtained by measuring the transmission notches over the signal spectra. The AOA is calculated from the relative time delay and the antenna spacing. The experiment results show that the measurement error is less than ±0.35 ps when the relative time delay changes from −14 to 16 ps. Auteurs: Zhaoyang Tu;Aijun Wen;Zhongguo Xiu;Wu Zhang;Mei Chen; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» Anisotropic Discrete Dual-Tree Wavelet Transform for Improved Classification of Trabecular Bone
 Résumé:This paper deals with a new anisotropic discrete dual-tree wavelet transform (ADDTWT) to characterize the anisotropy of bone texture. More specifically, we propose to extend the conventional discrete dual-tree wavelet transform (DDTWT) by using the anisotropic basis functions associated with the hyperbolic wavelet transform instead of isotropic spectrum supports. A texture classification framework is adopted to assess the performance of the proposed transform. The generalized Gaussian distribution is used to model the distribution of the sub-band coefficients. The estimated vector of parameters for each image is then used as input for the support vector machine classifier. Experiments were conducted on synthesized anisotropic fractional Brownian motion fields and on a real database composed of osteoporotic patients and control cases. Results show that the ADDTWT outperforms most of the competing anisotropic transforms with an area under curve rate of 93%. Auteurs: Hind Oulhaj;Mohammed Rziza;Aouatif Amine;Hechmi Toumi;Eric Lespessailles;Mohammed El Hassouni;Rachid Jennane; Apparue dans: IEEE Transactions on Medical Imaging Date publication: 10.-2017, volume: 36, issue:10, pages: 2077 - 2086 Editeur: IEEE Document complet vers site de l'éditeur
» Antenna Deembedding for mmWave Propagation Modeling and Field Measurement Validation at 73 GHz
 Résumé:In field measurements at millimeter-wave (mmWave) frequencies, the spatial propagation characteristics are usually obtained by using steerable high-gain horn antennas to compensate the large path loss. However, it is a challenging issue to deembed antenna patterns from the observed channel responses. This paper has two contributions. First, according to the steering-antenna sounding process, a spatial channel response model is designed, where the multipath propagation profile, antenna pattern, and channel response are spatially sampled and combined in a discrete convolutional form. Then, a low-complexity antenna deembedding algorithm, including two steps of deconvolutions, is proposed. Second, a field measurement campaign on the frequency-space mmWave channels in an office is presented to validate the method. The channels were sounded at 72.5 to 73.5 GHz using three horn antennas with different beam widths and gains. The omnidirectional angular channel responses (ACRs) were measured by rotating the receiver antenna. The observed and reconstructed ACRs are consistent, and the estimated antenna-free angular propagation profiles by using different horn antennas are also highly correlated, which validate the proposed antenna deembedding approach. Furthermore, the omnidirectional transfer functions in the mmWave band obtained using different horn antennas are compared, and the channel coherence bandwidth is analyzed based on the autocorrelation of the transfer functions. Auteurs: Ruonan Zhang;Yuliang Zhou;Xiaofeng Lu;Chang Cao;Qi Guo; Apparue dans: IEEE Transactions on Microwave Theory and Techniques Date publication: 10.-2017, volume: 65, issue:10, pages: 3648 - 3659 Editeur: IEEE Document complet vers site de l'éditeur
» Anti-Islanding Protection Relay for Medium Voltage Feeder With Multiple Distributed Generators
 Résumé:Large distributed generators (DGs) are usually connected to medium voltage (MV, typically up to 50 kV) feeders directly. Their anti-islanding protections mainly rely on transfer trips from upstream substations through communication media, which are expensive and time-consuming because of infrastructure. This paper presents a local anti-islanding protection relay (LPR) as an alternative for the traditional transfer trip in MV feeder applications. The basic idea of the proposed LPR is to short phase to neutral or phase to phase voltages by thyristors at the point of common coupling (PCC) of each DG when either of them is crossing zero; then both variations of the thyristor current and voltage harmonic distortion at the PCC are observed and measured, and they are able to indicate the operating mode of the DG unit in either grid-connected or islanding. Further, this approach is analyzed and discussed based on a single DG scenario and a complicated scenario with two DGs and one shunt capacitor bank. Finally, a lot of experiment results with different scenarios are obtained based on a scale-down testing platform, which has been built in our lab by using per-unit method from an actual MV feeder system. Auteurs: Hua F. Xiao;Zhijian Fang;Dewei Xu;Bala Venkatesh;Birendra Singh; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7874 - 7885 Editeur: IEEE Document complet vers site de l'éditeur
» Aperture Distributions for Maximum Endfire Directivity From a Continuous Line Source With a Uniform Phase Progression
 Résumé:An optimized aperture distribution is investigated to achieve the maximum endfire directivity for a continuous line source with a uniform phase progression. The optimization method has the advantages of simplicity and efficiency, in which the aperture distribution is expanded into a set of cosine functions and the optimization reduces to solving a constrained linear-least-squares problem. Based on the copious computed results from the optimization, an approximate closed-form expression is derived for the maximum directivity. The expression can serve as a bound for the endfire directivity for a line source with a uniform phase progression. It is found that the optimum directivity increases almost linearly with an increase of the normalized phase constant, but with a decrease in the radiated power. Nevertheless, the enhancement in the directivity is much higher than that in previously studied superdirectivity, under the same constraint in the ratio of reactive to radiated power. The current distribution does not oscillate widely as is does for superdirectivity, and is therefore more practical than for superdirectivity. Auteurs: Juhua Liu;David R. Jackson; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5123 - 5136 Editeur: IEEE Document complet vers site de l'éditeur
» Applicability of LED-Based Excitation Source for Defect Depth Resolved Frequency Modulated Thermal Wave Imaging
 Résumé:This paper proposes an energy efficient instrumentation set-up for pulse-compression thermal-wave imaging with a low-power LED excitation source. The set-up consists of three different subsystems that are synchronised in time. The individual systems consist of a LED modulation circuitry, reference signal measurement circuitry, and an IR camera trigger signal generation circuitry for frame capture. A separate reference acquisition circuitry is useful in quantifying defect depth resolution. This paper also proposes a nonuniform frame capture technique to reduce the memory allocation space of the recorded video. The technique is based on varying the sampling rate with a change in instantaneous frequency and is specifically useful for frequency modulated excitation signal. The proposed technique is implemented on a carbon fiber reinforced polymer test-piece. The variation of pulse compression parameters with different defect dimension is studied, and the results are verified with an electro-thermal simulator. Further, an objective comparison of pulse compression experiment for different experiment duration is presented. Auteurs: Deboshree Roy;Suneet Tuli; Apparue dans: IEEE Transactions on Instrumentation and Measurement Date publication: 10.-2017, volume: 66, issue:10, pages: 2658 - 2665 Editeur: IEEE Document complet vers site de l'éditeur
» Application of the Curvelet Transform for Clutter and Noise Removal in GPR Data
 Résumé:This paper presents a new method based on the curvelet transform to improve the readability of ground penetrating radar (GPR) data during localization works of buried pipes. The localization is achieved by the detection of hyperbolas in the GPR cross section, also called B-scan. However, GPR antenna collects abundant information from the ground, which can partially hide useful information, especially echoes from the pipes (i.e., hyperbolas). In order to highlight these echoes, it is important to reduce noise and to remove undesirable items such as the clutter and column artifacts. For this purpose, we propose to use the curvelet transform in a three processing step method: clutter, noise, and column artifact removal. Thanks to prior information on the distribution of the coefficients and on the orientation of the clutter and artifacts, we are able to reduce them in the B-scan. These steps can be used independently giving more flexibility to the operator. Moreover, the processing is fast to compute and requires only one easily tunable parameter. This is appropriate for a computation in real-time by nonexpert operators. Our method has been applied to real data acquired on a test area and under real conditions. We show the proposed method presents satisfying qualitative and quantitative results compared to other methods. Auteurs: Guillaume Terrasse;Jean-Marie Nicolas;Emmanuel Trouvé;Émeline Drouet; Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Date publication: 10.-2017, volume: 10, issue:10, pages: 4280 - 4294 Editeur: IEEE Document complet vers site de l'éditeur
» Applying Transmission Line Theory to Study the Transmitting Turn-OFF Current in a Long Grounded Wire
 Résumé:A long grounded wire in the transient electromagnetic (TEM) surveys is usually considered by using the lumped parameter circuit model, which fails to explicate the early turn-OFF current with crucial importance for TEM surveys. In this paper, the transmission line model is introduced for the first time to explicate the early turn-OFF current in the long grounded wire considering the high frequency at early turn-OFF stage. The transmission line model suitable for the long grounded wire is constructed, then the calculation formulas of the distributed parameters and load impedance are analyzed, and the transfer function utilized to simulate the current at any position of the transmission line is also derived. The simulation is performed in the frequency domain with subsequent transformation into the time domain, and the simulation results are in good agreement with the experimental data. The early turn-OFF currents depending on the earth resistivity vary with the position in the long grounded wire. Therefore, the early time TEM response differs from that predicted by the classical theory of the TEM surveys. This proposed model can guide the realization of the minimum current turn-OFF duration, which will help to reduce the detection blind spot and this paper provides new ideas and prospects for early response data and current waveform data for interpretation in the geophysics detection. Auteurs: Zongyang Shi;Lihua Liu;Pan Xiao;Zhi Geng;Guangyou Fang; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5112 - 5122 Editeur: IEEE Document complet vers site de l'éditeur
» Approximate Mean Delay Analysis for a Signalized Intersection With Indisciplined Traffic
 Résumé:Mixed vehicular traffic comprising small cars and two-wheeled vehicles (called motorcycles in this paper) arrive at a lane of a signalized road intersection. The traffic does not follow lane-discipline, in that the arriving vehicles do not necessarily queue up one behind the other. The motorcycles are small enough to stand side-by-side with cars or other motorcycles, so as to fill up the width of the lane. With such queue joining behavior, the waiting vehicles form batches, comprising motorcycles, and at most one car. During the green signal period the vehicles in the head-of-the-line batch exit the intersection together. In this paper, assuming a Poisson point process model for vehicle arrivals, we have provided an approximate analysis of such a queueing system. Our approach is to use an assembly queue model for the batching process. The batches generated by the assembly queue enter an interrupted M/SemiMarkov/1 (or M/SM/1) queue. By analyzing the assembly queue we characterize the batch input process for the interrupted M/SM/1 queue. We then develop an extension of the Webster mean delay formula for obtaining the approximate mean delay in the interrupted M/SM/1 queue. Numerical results from the analysis are compared with simulation results. The analysis is shown to be accurate in predicting the increase in the system capacity due to the batching behavior. Auteurs: Samrat Mukhopadhyay;Pramod M. J.;Anurag Kumar; Apparue dans: IEEE Transactions on Intelligent Transportation Systems Date publication: 10.-2017, volume: 18, issue:10, pages: 2750 - 2762 Editeur: IEEE Document complet vers site de l'éditeur
» Approximation Algorithms for Charging Reward Maximization in Rechargeable Sensor Networks via a Mobile Charger
 Résumé:Wireless energy transfer has emerged as a promising technology for wireless sensor networks to power sensors with controllable yet perpetual energy. In this paper, we study sensor energy replenishment by employing a mobile charger (charging vehicle) to charge sensors wirelessly in a rechargeable sensor network, so that the sum of charging rewards collected from all charged sensors by the mobile charger per tour is maximized, subject to the energy capacity of the mobile charger, where the amount of reward received from a charged sensor is proportional to the amount of energy charged to the sensor. The energy of the mobile charger will be spent on both its mechanical movement and sensor charging. We first show that this problem is NP-hard. We then propose approximation algorithms with constant approximation ratios under two different settings: one is that a sensor will be charged to its full energy capacity if it is charged; another is that a sensor can be charged multiple times per tour but the total amount of energy charged is no more than its energy demand prior to the tour. We finally evaluate the performance of the proposed algorithms through experimental simulations. The simulation results demonstrate that the proposed algorithms are very promising, and the solutions obtained are fractional of the optimum. To the best of our knowledge, the proposed algorithms are the very first approximation algorithms with guaranteed approximation ratios for the mobile charger scheduling in a rechargeable sensor network under the energy capacity constraint on the mobile charger. Auteurs: Weifa Liang;Zichuan Xu;Wenzheng Xu;Jiugen Shi;Guoqiang Mao;Sajal K. Das; Apparue dans: IEEE/ACM Transactions on Networking Date publication: 10.-2017, volume: 25, issue:5, pages: 3161 - 3174 Editeur: IEEE Document complet vers site de l'éditeur
» Arc Flash Visible Light Intensity as Viewed From Human Eyes
 Résumé:Human eye can be damaged by the intense light from an arc flash event. Though it is certain that high intensity visible light will be emitted during an arc flash event, there is limited research that provides quantitative light intensity estimation during different arcing incidents as viewed from human eyes. To provide better understanding of the light intensity during arc flash events, this paper proposes an arc flash light intensity estimation model based on approximately 1500 measurement data from arc flash tests using ambient light sensors, which are capable of measuring the light intensity of the arc flash as perceived by the human eyes. The proposed light intensity estimation model can be used to evaluate the potential impact of an arc flash on the human eyes. In addition, the autodarkening welding lens is used in the arc flash testing to explore its effectiveness in attenuating the light intensity and mitigating the exposure to the light hazard during an arc flash event. Auteurs: Shiuan-Hau Rau;Zhenyuan Zhang;Wei-Jen Lee;David A. Dini; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 5068 - 5077 Editeur: IEEE Document complet vers site de l'éditeur
» Architecture Design of a Memory Subsystem for Massive MIMO Baseband Processing
 Résumé:This brief presents an on-chip memory subsystem for massive multiple-input-multiple-output (MIMO) baseband processing at the base station. In massive MIMO systems, the required memory bandwidth and capacity are orders of magnitude higher than those used in conventional wireless systems, due to the large number of serving antennas. These are further combined with design targets on low access latency and flexibility in data organization and access modes. This brief applies and improves the concept of parallel memories to achieve the challenging design target with low hardware overhead. As a case study, a memory subsystem for 128-antenna and 16-user massive MIMO systems is evaluated using ST 28-nm technology. According to postlayout simulation results, the proposed memory subsystem provides 512-Gb/s throughput and offers 1-Mb capacity with a cost of 0.30 mm2. Auteurs: Yangxurui Liu;Liang Liu;Viktor Öwall; Apparue dans: IEEE Transactions on Very Large Scale Integration Systems Date publication: 10.-2017, volume: 25, issue:10, pages: 2976 - 2980 Editeur: IEEE Document complet vers site de l'éditeur
» ARCNET Never Received Enough Credit [History]
 Résumé:In the March 2017 issue of IEEE Industrial Electronics Magazine, the authors of "The Future of Industrial Communication" provided a comprehensive chart of industrial communication milestones ranging from the 1960s to the present [1]. But there was one glaring omission-the Attached Resource Computer Network (ARCNET). As a former chair of the ARCNET Trade Association (ATA), I feel obligated to defend ARCNET as the first local area network (LAN), which is still in use today [2]. It is a technology that impacted both the office and industrial automation industries. It is elegant, fast, robust-and it works! The technology was deemed by the press as "the Rodney Dangerfield of network computing," and its proponents were called fanatical [3]. Although ARCNET has failed to receive the recognition it deserves, it is a successful technology that has been used in applications never imagined by its creators. Auteurs: George Thomas; Apparue dans: IEEE Industry Applications Magazine Date publication: 10.-2017, volume: 23, issue:5, pages: 7 - 13 Editeur: IEEE Document complet vers site de l'éditeur
» Area/Energy-Efficient Gammatone Filters Based on Stochastic Computation
 Résumé:This paper introduces area/energy-efficient gammatone filters based on stochastic computation. The gammatone filter well expresses the performance of human auditory peripheral mechanism and has a potential of improving advanced speech communications systems, especially hearing assisting devices and noise robust speech-recognition systems. Using stochastic computation, a power-and-area hungry multiplier used in a digital filter is replaced by a simple logic gate, leading to area-efficient hardware. However, a straightforward implementation of the stochastic gammatone filter suffers from significantly low accuracy in computation, which results in a low dynamic range (a ratio of the maximum to minimum magnitude) due to a small value of a filter gain. To improve the computation accuracy, gain-balancing techniques are presented that represent the original gain as the product of multiple larger gains introduced at the second-order sections. In addition, dynamic scaling techniques are proposed that scales up small values only on stochastic domain in order to reduce the number of stochastic bits required while maintaining the computation accuracy. For performance comparisons, the proposed stochastic gammatone filters are designed and evaluated on taiwan semiconductor manufacturing company (TSMC) 65-nm CMOS technology. As a result, the proposed filter achieves an area reduction of 90.7% and an energy reduction of 91.8% in comparison with a fixed-point gammatone filter at the same sampling frequency and a comparable dynamic range. Auteurs: Naoya Onizawa;Shunsuke Koshita;Shuichi Sakamoto;Masahide Abe;Masayuki Kawamata;Takahiro Hanyu; Apparue dans: IEEE Transactions on Very Large Scale Integration Systems Date publication: 10.-2017, volume: 25, issue:10, pages: 2724 - 2735 Editeur: IEEE Document complet vers site de l'éditeur
» Arrays of Position-Sensitive Virtual Frisch-Grid CdZnTe Detectors: Results From a $4times 4$ Array Prototype
 Résumé:Position-sensitive virtual Frisch-grid (VFG) CdZnTe (CZT) detectors offer a unique capability for correcting the response nonuniformities caused by crystal defects. This allowed us to achieve high energy resolution, while using typical-grade commercial CZT crystals with relaxed requirements to their quality, thus reducing the overall cost of detectors. Another advantage of the VFG detectors is that they can be integrated into arrays and used in small compact hand-held instruments or large-area gamma cameras that will enhance detection capability for many practical applications, including nonproliferation, medical imaging, and gamma-ray astronomy. Here, we present the results from testing small array prototypes coupled with front-end application-specified integrated circuit. Each detector in the array is furnished with 5-mm-wide charge-sensing pads placed near the anode. The pads signals are converted into XY coordinates, which combined with the cathode signals (for Z coordinates) provide 3-D position information of all interaction points. The basic array consists of a number of detectors grouped into $2times 2$ subarrays, each having a common cathode made by connecting together the cathodes of the individual detectors. These features can significantly improve the performance of detectors while using typical-grade low-cost CZT crystals to reduce the overall cost of the proposed instrument. Auteurs: L. A. Ocampo Giraldo;A. E. Bolotnikov;G. S. Camarda;S. Cheng;G. De Geronimo;A. McGilloway;J. Fried;D. Hodges;A. Hossain;K. Ünlü;M. Petryk;V. Vidal;E. Vernon;G. Yang;R. B. James; Apparue dans: IEEE Transactions on Nuclear Science Date publication: 10.-2017, volume: 64, issue:10, pages: 2698 - 2705 Editeur: IEEE Document complet vers site de l'éditeur
» Artificial Noise Injection for Securing Single-Antenna Systems
 Résumé:We propose a novel artificial noise (AN) injection scheme for wireless systems over quasi-static fading channels, in which a single-antenna transmitter sends confidential messages to a half-duplex receiver in the presence of an eavesdropper. Different from classical AN injection schemes, which rely on a multiantenna transmitter or external helpers, our proposed scheme is applicable to the scenario, where the legitimate transceivers are very simple. We analyze the performance of the proposed scheme and optimize the design of the transmission. Our results highlight that perfect secrecy is always achievable by properly designing the AN injection scheme. Auteurs: Biao He;Yechao She;Vincent K. N. Lau; Apparue dans: IEEE Transactions on Vehicular Technology Date publication: 10.-2017, volume: 66, issue:10, pages: 9577 - 9581 Editeur: IEEE Document complet vers site de l'éditeur
» Assessment of the Influence of Losses on the Performance of the Electromagnetic Time Reversal Fault Location Method
 Résumé:Electromagnetic time reversal (EMTR) has been shown to be an efficient method for locating faults in ac and dc power grids. In the available literature, the back-propagation medium has been considered to have identical losses as the directtime medium. However, the telegrapher's equations describing the traveling wave propagation are time-reversal invariant if and only if inverted losses are considered in the back-propagation phase. This paper presents an analysis of the impact of losses on the performance of the EMTR-based fault location method for power networks. In this respect, three back-propagation models are proposed, analyzed, and compared. It is shown that a lossy back-propagation model, for which the wave equations are not rigorously time-reversal invariant, results in accurate fault locations. Finally, an EMTR fault location system based on the lossy back-propagation model and a fast electromagnetic transient simulation platform is developed and its performances validated. Auteurs: Reza Razzaghi;Gaspard Lugrin;Farhad Rachidi;Mario Paolone; Apparue dans: IEEE Transactions on Power Delivery Date publication: 10.-2017, volume: 32, issue:5, pages: 2303 - 2312 Editeur: IEEE Document complet vers site de l'éditeur
» Asynchronous Multirate Multisensor Data Fusion Over Unreliable Measurements With Correlated Noise
 Résumé:In this paper, the problem of optimal state estimation is studied for fusion of asynchronous multirate multiscale sensors with unreliable measurements and correlated noise. The noise of different sensors is cross-correlated and coupled with the system noise of the previous step and the same time step. The system is described at the highest sampling rate with different sensors observing a single target independently with multiple sampling rates. An optimal state estimation algorithm based on iterative estimation of the white noise estimator is presented, which makes full use of the observation information effectively, overcomes the packet loss, data fault, unreliable factors, and improves the precision and the robustness of the system state estimation. A numerical example is used to illustrate the effectiveness of the presented algorithm. Auteurs: Lu Jiang;Liping Yan;Yuanqing Xia;Qiao Guo;Mengyin Fu;Kunfeng Lu; Apparue dans: IEEE Transactions on Aerospace and Electronic Systems Date publication: 10.-2017, volume: 53, issue:5, pages: 2427 - 2437 Editeur: IEEE Document complet vers site de l'éditeur
» Asynchronous Physical-Layer Network Coding: Symbol Misalignment Estimation and Its Effect on Decoding
 Résumé:In asynchronous physical-layer network coding (APNC) systems, the symbols from multiple transmitters to a common receiver may be misaligned. Knowledge of the amount of symbol misalignment, hence its estimation, is important to PNC decoding. This paper addresses the problems of symbol-misalignment estimation and optimal PNC decoding given the misalignment estimate, assuming the APNC system uses the root-raised-cosine pulse to carry signals (RRC-APNC). Our contributions are as follows. First, we put forth an optimal symbol-misalignment estimator that makes use of double baud-rate samples. Second, we devise optimal RRC-APNC decoders in the presence of non-exact symbol-misalignment estimates. In particular, we show how to whiten the colored noise in the double baud-rate samples to simplify the design of optimal decoders. Third, we investigate the decoding performance of various estimation-and-decoding schemes for RRC-APNC. Extensive simulations show that: 1) our double baud-rate estimator yields substantially more accurate symbol-misalignment estimates than the baud-rate estimator does; the mean square error gains are up to 8 dB and 2) an overall estimation-and-decoding scheme in which both estimation and decoding are based on double baud-rate samples yields much better performance than other schemes. Compared with a scheme in which both estimation and decoding are based on baud-rate samples, the double baud-rate sampling scheme yields 4.5 dB gains on symbol error rate performance in an additive white Gaussian noise channel, and 2 dB gains on packet error rate performance in a Rayleigh fading channel. Auteurs: Yulin Shao;Soung Chang Liew;Lu Lu; Apparue dans: IEEE Transactions on Wireless Communications Date publication: 10.-2017, volume: 16, issue:10, pages: 6881 - 6894 Editeur: IEEE Document complet vers site de l'éditeur
» Audible Noise Characteristics of Filter Capacitors Used in HVDC Converter Stations
 Résumé:This paper presents a detailed investigation of audible noise characterization of filter capacitors by investigating the noise radiation characteristics and analyzing the effect of voltage frequency, phase angle, and magnitude on a single capacitor unit. First, the noise radiation for capacitor surfaces was characterized theoretically using finite rectangular plate model and experimentally measured in a semianechoic room. Second, voltage frequency impact on the noise distribution was investigated through simulation. The simulation results show that noise directivity increases with increasing frequency. The excitation frequency impact on the radiation ratio and the noise level was characterized through a sweep-frequency experiment. Our investigations show that the noise frequency response below 500 Hz is quite low, while from 500 to 2000 Hz, it is significant and increases slowly. Third, the impact of the voltage phase angle on the noise level was investigated. The results show a noise-level difference of 3.9 dB for different phase angles. Finally, we present the voltage magnitude impact on the noise level. Our theoretical analysis and experimental study show a linear relationship between the sound power level and the logarithm of the voltage magnitude with a slope of 40. Auteurs: Lingyu Zhu;Jinyu Li;Yuhang Shi;Habibur Rehman;Shengchang Ji; Apparue dans: IEEE Transactions on Power Delivery Date publication: 10.-2017, volume: 32, issue:5, pages: 2263 - 2271 Editeur: IEEE Document complet vers site de l'éditeur
» Augmented Reality Marker Hiding with Texture Deformation
 Résumé:Augmented reality (AR) marker hiding is a technique to visually remove AR markers in a real-time video stream. A conventional approach transforms a background image with a homography matrix calculated on the basis of a camera pose and overlays the transformed image on an AR marker region in a real-time frame, assuming that the AR marker is on a planar surface. However, this approach may cause discontinuities in textures around the boundary between the marker and its surrounding area when the planar surface assumption is not satisfied. This paper proposes a method for AR marker hiding without discontinuities around texture boundaries even under nonplanar background geometry without measuring it. For doing this, our method estimates the dense motion in the marker’s background by analyzing the motion of sparse feature points around it, together with a smooth motion assumption, and deforms the background image according to it. Our experiments demonstrate the effectiveness of the proposed method in various environments with different background geometries and textures. Auteurs: Norihiko Kawai;Tomokazu Sato;Yuta Nakashima;Naokazu Yokoya; Apparue dans: IEEE Transactions on Visualization and Computer Graphics Date publication: 10.-2017, volume: 23, issue:10, pages: 2288 - 2300 Editeur: IEEE Document complet vers site de l'éditeur
» Automated Classification of Breast Cancer Stroma Maturity From Histological Images
 Résumé:Objective: The tumor microenvironment plays a crucial role in regulating tumor progression by a number of different mechanisms, in particular, the remodeling of collagen fibers in tumor-associated stroma, which has been reported to be related to patient survival. The underlying motivation of this work is that remodeling of collagen fibers gives rise to observable patterns in hematoxylin and eosin (H&E) stained slides from clinical cases of invasive breast carcinoma that the pathologist can label as mature or immature stroma. The aim of this paper is to categorise and automatically classify stromal regions according to their maturity and show that this classification agrees with that of skilled observers, hence providing a repeatable and quantitative measure for prognostic studies. Methods: We use multiscale basic image features and local binary patterns, in combination with a random decision trees classifier for classification of breast cancer stroma regions-of-interest (ROI). Results: We present results from a cohort of 55 patients with analysis of 169 ROI. Our multiscale approach achieved a classification accuracy of 84%. Conclusion: This work demonstrates the ability of texture-based image analysis to differentiate breast cancer stroma maturity in clinically acquired H&E-stained slides at least as well as skilled observers. Auteurs: Sara Reis;Patrycja Gazinska;John H. Hipwell;Thomy Mertzanidou;Kalnisha Naidoo;Norman Williams;Sarah Pinder;David J. Hawkes; Apparue dans: IEEE Transactions on Biomedical Engineering Date publication: 10.-2017, volume: 64, issue:10, pages: 2344 - 2352 Editeur: IEEE Document complet vers site de l'éditeur
» Automated Detection of Ice and Open Water From Dual-Polarization RADARSAT-2 Images for Data Assimilation
 Résumé:In this paper, we present a new technique for automated detection of ice and open water from RADARSAT-2 ScanSAR dual-polarization HH-HV images. Probability of the presence of ice within 2.05 km $\times2.05$ km areas is modeled using a form of logistic regression as a function of the difference between the wind speeds estimated from synthetic aperture radar (SAR) data and those obtained from numerical weather prediction short-term forecasts, the spatial correlation between HH and HV backscatter signals, and the spatial standard deviation of the wind speed estimated from SAR. The resulting ice probability model was built based on thousands of SAR images and corresponding Canadian Ice Service (CIS) Image Analysis products covering all seasons and all Canadian and adjacent Arctic regions being monitored by CIS. Extensive verification of the proposed technique was conducted for an entire year (2013) against independent Image Analysis products and Interactive Multisensor Snow and Ice Mapping System ice extent products. Using a probability threshold of 0.95, 72.2% of the retrievals were classified as either ice or open water with an accuracy of 99.2% in the most clean verification scenario against Image Analysis pure ice and water data. The ability to obtain such a large number of retrievals with a very high accuracy makes it feasible to assimilate the resulting retrievals in an ice prediction system. Consequently, the developed ice/water retrieval technique will be implemented as a part of the data assimilation component of the operational Environment and Climate Change Canada Regional Ice-Ocean Prediction System. Auteurs: Alexander S. Komarov;Mark Buehner; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5755 - 5769 Editeur: IEEE Document complet vers site de l'éditeur
» Automated Extraction and Clustering of Requirements Glossary Terms
 Résumé:A glossary is an important part of any software requirements document. By making explicit the technical terms in a domain and providing definitions for them, a glossary helps mitigate imprecision and ambiguity. A key step in building a glossary is to decide upon the terms to include in the glossary and to find any related terms. Doing so manually is laborious, particularly for large requirements documents. In this article, we develop an automated approach for extracting candidate glossary terms and their related terms from natural language requirements documents. Our approach differs from existing work on term extraction mainly in that it clusters the extracted terms by relevance, instead of providing a flat list of terms. We provide an automated, mathematically-based procedure for selecting the number of clusters. This procedure makes the underlying clustering algorithm transparent to users, thus alleviating the need for any user-specified parameters. To evaluate our approach, we report on three industrial case studies, as part of which we also examine the perceptions of the involved subject matter experts about the usefulness of our approach. Our evaluation notably suggests that: (1) Over requirements documents, our approach is more accurate than major generic term extraction tools. Specifically, in our case studies, our approach leads to gains of 20 percent or more in terms of recall when compared to existing tools, while at the same time either improving precision or leaving it virtually unchanged. And, (2) the experts involved in our case studies find the clusters generated by our approach useful as an aid for glossary construction. Auteurs: Chetan Arora;Mehrdad Sabetzadeh;Lionel Briand;Frank Zimmer; Apparue dans: IEEE Transactions on Software Engineering Date publication: 10.-2017, volume: 43, issue:10, pages: 918 - 945 Editeur: IEEE Document complet vers site de l'éditeur
» Automated Transportation of Biological Cells for Multiple Processing Steps in Cell Surgery
 Résumé:Most studies on automated cell transportation are single-task oriented. Results from these investigations hardly meet the increasing demand for emerging cell surgery operations that usually require a series of manipulation tasks with multiple processing steps. In this paper, automated cell transportation to accomplish a multistep process in cell surgery was investigated. A novel control system that can manipulate grouped cells to move into different task regions sequentially and continuously without interruption was developed based on a robot-aided optical tweezers manipulation system. A potential field-based controller was designed to achieve multistep processing control, where the new concepts of contractive coalition and switching region were incorporated into tweezers–cell coalition. The success of this controller lies in simultaneously controlling the positions of the optical tweezers, trapping multiple cells effectively, and avoiding collisions in a unified manner. Simulations and experiments of transferring a group of cells to a number of task regions were performed to demonstrate the effectiveness of the proposed approach. Note to Practitioners—This paper was motivated by the challenging problem of automated transportation of grouped cells to several predefined task regions in emerging cell surgery with multiple processing steps. Existing automated cell transportation studies are mainly single-task oriented, thereby making them inapplicable to cell surgery operations, because a series of sequential processing steps are usually involved in these operations. This paper provides a novel control strategy based on a robot-aided optical tweezers manipulation system to efficiently transport cells into different task regions sequentially without interruption. Unlike the previous cell transportation studies where the goal positions of single cells must be specified early, here only the desired task regions are i- entified in the controller implementation, making the proposed strategy a better fit for actual cell surgery practice. Auteurs: Hao Yang;Xiangpeng Li;Yunhui Liu;Dong Sun; Apparue dans: IEEE Transactions on Automation Science and Engineering Date publication: 10.-2017, volume: 14, issue:4, pages: 1712 - 1721 Editeur: IEEE Document complet vers site de l'éditeur
» Automatic and Fast PCM Generation for Occluded Object Detection in High-Resolution Remote Sensing Images
 Résumé:Partial configuration model (PCM) is an occluded object detection method in high-resolution remote sensing images (HR-RSIs) based on the deformable part-based model (DPM). However, it needs extra category predefinition, considerable part-level annotation, and repeated multimodel training. In this letter, an automatic and fast PCM generation method is proposed based on a novel part sharing mechanism. We propose to share parts from one trained DPM model (tDPM) among different models of partial configurations (PCs) to address the above problems. PCs are first designed according to part anchors of tDPM. The model is then generated through corresponding parts selection, root coverage cropping, and elements reweighing. This method avoids the need for manual category predefinition and part-level annotation, while largely reducing the computation of PCM training. Experimental results on three HR-RSI data sets show that the proposed method obtains a training speedup of $6.7\times$ and $2\times$ for each PC of airplane and ship categories, while achieving a comparable accuracy compared with PCM. Auteurs: Shaohua Qiu;Gongjian Wen;Zhipeng Deng;Yaxiang Fan;Bingwei Hui; Apparue dans: IEEE Geoscience and Remote Sensing Letters Date publication: 10.-2017, volume: 14, issue:10, pages: 1730 - 1734 Editeur: IEEE Document complet vers site de l'éditeur
» Automatic Identification of Weave Patterns of Checked and Colored Fabrics Using Optical Coherence Tomography
 Résumé:Identifying the weave pattern of fabrics can be done manually or automatically. Carrying out the weave recognition automatically will reduce the procedure time and error rates since automatic systems can perform successive measurements at high speeds and with great repeatability and quality. Woven fabric repeat identification systems that are automatic, usually work by employing complex algorithms and techniques. It is known that these automatic techniques struggle when trying to identify highly complex patterns, composing of a combination of different structures, figures, and colors. For example, image processing algorithms are known to make errors when dealing with checked and colored fabrics. In this paper, we apply the spectral domain optical coherence tomography imaging technique for identifying checked and colored woven fabric repeat automatically. This is achieved by employing an in-house written JAVA code that extracts the weave pattern from the tomography images. We show that automatic identification of weave pattern of checked and colored fabrics can be performed nondestructively by employing optical coherence tomography. Auteurs: Metin Sabuncu;Hakan Ozdemir;Mete U. Akdogan; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» Automatic MTPA Tracking in IPMSM Drives: Loop Dynamics, Design, and Auto-Tuning
 Résumé:Maximum Torque Per Ampere (MTPA) based on motor parameters is a common approach to achieve high efficiency and torque density in Interior Permanent Magnet Synchronous Machine Drives (IPMSMs). However, uncertainty (e.g., due to identification errors, magnetic saturation, or temperature variation) results in undesired deviation from the optimal operating trajectory. To solve this problem, MTPA tracking methods have been proposed, which exploit signal injection to search the minimum current point for a certain load torque in a closed-loop fashion. Closed-form design of the MTPA tracking loop dynamics has never been addressed in past literature and represents the main topic of this paper. A recent and efficient tracking method has been considered for the analysis and case study, i.e., [14]. Nonlinear small-signal gain of the loop can be calculated in closed form, leading to two valuable results. Dynamics can be programmed by optimal design of the tracking regulator, and online adaptation can be applied, making the designed MTPA tracking dynamics invariant with the operating point. A straightforward and effective solution is proposed for the regulator design, which allows us to obtain the desired bandwidth and first-order tracking response in the whole range of operation, being also suitable for auto-tuning and online adaptation. The method has been studied analytically and in simulation, also considering the influence of noise and parametric uncertainties. Finally the technique has been implemented on the hardware of a commercial industrial drive, proving the effectiveness of the proposal. The concepts described in this paper, design approach and adaptation strategy, analyzed here for the first time, are general and can be applied to any control scheme implementing closed-loop MTPA tracking. Auteurs: Nicola Bedetti;Sandro Calligaro;Christian Olsen;Roberto Petrella; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4547 - 4558 Editeur: IEEE Document complet vers site de l'éditeur
» Automatic Nuclear Segmentation Using Multiscale Radial Line Scanning With Dynamic Programming
 Résumé:In the diagnosis of various cancers by analyzing histological images, automatic nuclear segmentation is an important step. However, nuclear segmentation is a difficult problem because of overlapping nuclei, inhomogeneous staining, and presence of noisy pixels and other tissue components. In this paper, we present an automatic technique for nuclear segmentation in skin histological images. The proposed technique first applies a bank of generalized Laplacian of Gaussian kernels to detect nuclear seeds. Based on the detected nuclear seeds, a multiscale radial line scanning method combined with dynamic programming is applied to extract a set of candidate nuclear boundaries. The gradient, intensity, and shape information are then integrated to determine the optimal boundary for each nucleus in the image. Nuclear overlap limitation is finally imposed based on a Dice coefficient measure such that the obtained nuclear contours do not severely intersect with each other. Experiments have been thoroughly performed on two datasets with H&E and Ki-67 stained images, which show that the proposed technique is superior to conventional schemes of nuclear segmentation. Auteurs: Hongming Xu;Cheng Lu;Richard Berendt;Naresh Jha;Mrinal Mandal; Apparue dans: IEEE Transactions on Biomedical Engineering Date publication: 10.-2017, volume: 64, issue:10, pages: 2475 - 2485 Editeur: IEEE Document complet vers site de l'éditeur
» Automatic Rich Map Semantics Identification Through Smartphone-Based Crowd-Sensing
 Résumé:Digital maps have become a part of our daily lives with a growing number of commercial and free map services. However, these services still have a huge potential for enhancement with rich semantic information to support a large class of mapping applications. In this paper, we present Map++, a system that leverages commodity off-the-shelf smartphones in a crowd-sensing approach to automatically enrich digital maps with different road semantics like tunnels, bumps, bridges, footbridges, crosswalks, road capacity, among others. Our analysis shows that the smartphones sensors, whether with a user riding a vehicle or walking, get affected by the different road features which can be mined to extend the features of both free and commercial mapping services. Map++ leverages these detected features and employs a probabilistic framework that can handle the heterogeneity and uncertainty in the crowd-sensed data to update the digital maps. We present the design and implementation of Map++ and evaluate it in four cities. Our evaluation shows that we can detect different map features accurately with 4 percent false positive and 8 percent false negative rates for in-vehicle traces, and 3 percent false positive and 4 percent false negative rates for pedestrian traces. Moreover, we show that Map++ has a small energy footprint on the cell-phones, highlighting its promise as a ubiquitous digital maps enriching service. Auteurs: Heba Aly;Anas Basalamah;Moustafa Youssef; Apparue dans: IEEE Transactions on Mobile Computing Date publication: 10.-2017, volume: 16, issue:10, pages: 2712 - 2725 Editeur: IEEE Document complet vers site de l'éditeur
» Automatically Enforcing Security SLAs in the Cloud
 Résumé:Dealing with the provisioning of cloud services granted by Security SLAs is a very challenging research topic. At the state of the art, the main related issues involve: (i) representing security features so that they are understandable by both customers and providers and measurable (by means of verifiable security-related Service Level Objectives (SLOs)), (ii) automating the provisioning of security mechanisms able to grant desired security features (by means of a security-driven resource allocation process), and (iii) continuously monitoring the services in order to verify the fulfillment of specified Security SLOs (by means of cloud security monitoring solutions). We propose to face the Security SLA life cycle management with a framework able to enrich cloud applications with security features. In this paper we (i) present a novel Security SLA model and (ii) illustrate a security-driven planning process that can be adopted to determine the (optimum) deployment of security-related software components. Such process takes into account both specific implementation constraints of the security components to be deployed and customers security requirements, and enables the automatic provisioning and configuration of all needed resources. In order to demonstrate the applicability of the approach, we present and discuss a practical application of the model on a real case study. Auteurs: Valentina Casola;Alessandra De Benedictis;Mădălina Eraşcu;Jolanda Modic;Massimiliano Rak; Apparue dans: IEEE Transactions on Services Computing Date publication: 10.-2017, volume: 10, issue:5, pages: 741 - 755 Editeur: IEEE Document complet vers site de l'éditeur
» Backstepping Design of Robust State Feedback Regulators for Linear $2 \times 2$ Hyperbolic Systems
 Résumé:This technical note deals with the robust output regulation problem for boundary controlled linear $2 \times 2$ hyperbolic systems. Thereby, the output to be controlled can be located at one of the boundaries or is a pointwise in-domain output. By utilizing the internal model principle, a state feedback regulator is determined for a finite-dimensional signal model describing the exogenous signals. This amounts to stabilizing a hyperbolic PDE-ODE cascade coupled at an intermediate point. For this, a systematic backstepping method is developed to determine the stabilizing state feedback controller. The solvability of the considered output regulation problem can easily be verified on the basis of the nominal plant transfer behaviour. For non-destabilizing model uncertainties the robustness of the achieved output regulation is verified. An uncertain hyperbolic system with an in-domain output illustrates the results of the technical note. Auteurs: Joachim Deutscher; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5240 - 5247 Editeur: IEEE Document complet vers site de l'éditeur
» Backstepping Fuzzy Adaptive Control for a Class of Quantized Nonlinear Systems
 Résumé:This paper proposes a new adaptive controller for a class of uncertain nonlinear systems with a quantized signal. Fuzzy logic systems are utilized to approximate nonlinear terms without imposing prior matching conditions required. A hysteretic type of quantizer is incorporated to reduce chattering. A new adaptive backstepping controller is designed to guarantee that the underlying uncertain nonlinear system is semiglobally uniformly ultimately bounded. Two numerical examples are presented to demonstrate the effectiveness and potential of the proposed techniques. Auteurs: Wenhui Liu;Cheng-Chew Lim;Peng Shi;Shengyuan Xu; Apparue dans: IEEE Transactions on Fuzzy Systems Date publication: 10.-2017, volume: 25, issue:5, pages: 1090 - 1101 Editeur: IEEE Document complet vers site de l'éditeur
» Bacterial Relay for Energy-Efficient Molecular Communications
 Résumé:In multi-cellular organisms, molecular signaling spans multiple distance scales and is essential to tissue structure and functionality. Molecular communications is increasingly researched and developed as a key subsystem in the Internet-of-Nano-Things paradigm. While short range microscopic diffusion communications is well understood, longer range channels can be inefficient and unreliable. Static and mobile relays have been proposed in both conventional wireless systems and molecular communication contexts. In this paper, our main contribution is to analyze the information delivery energy efficiency of bacteria mobile relays. We discover that these mobile relays offer superior energy efficiency compared with pure diffusion information transfer over long diffusion distances. This paper has widespread implications ranging from understanding biological processes to designing new efficient synthetic biology communication systems. Auteurs: Song Qiu;Werner Haselmayr;Bin Li;Chenglin Zhao;Weisi Guo; Apparue dans: IEEE Transactions on NanoBioscience Date publication: 10.-2017, volume: 16, issue:7, pages: 555 - 562 Editeur: IEEE Document complet vers site de l'éditeur
» Balanced Tri-Band Bandpass Filter Design Using Octo-Section Stepped-Impedance Ring Resonator With Open Stubs
 Résumé:A balanced tri-band bandpass filter (BPF) is proposed based on octo-section stepped-impedance ring resonator (SIRR). The relation and design graphs between the differential-mode (DM) and common-mode (CM) characteristics with different physical parameters are analyzed. It reveals that the proposed SIRR has more degrees of freedom in controlling DM and CM characteristics for tri-band design with excellent out-of-band performances and high CM suppression. Moreover, the SIRR is loaded by open stubs with different lengths to further improve the CM suppression. Finally, a balanced tri-band BPF prototype is fabricated and measured. Good agreement between simulated and experimental results verifies this design method. Auteurs: Haiwen Liu;Yi Song;Baoping Ren;Pin Wen;Xuehui Guan;Hexiu Xu; Apparue dans: IEEE Microwave and Wireless Components Letters Date publication: 10.-2017, volume: 27, issue:10, pages: 912 - 914 Editeur: IEEE Document complet vers site de l'éditeur
» Balancing of Peak Currents Between Paralleled SiC MOSFETs by Drive-Source Resistors and Coupled Power-Source Inductors
 Résumé:The peak currents between two paralleled SiC MOSFETs could differ significantly due to the mismatch in threshold voltages Vth. The method described herein employs passive compensation (drive-source resistors and coupled power-source inductors) to balance the peak currents using one gate driver, no sensors, and no feedback- without increasing total switching loss when equivalent gate-drive resistance (Rg + 0.5Rk) is kept constant. This solution works for both polarities of Vth mismatch and forces balancing from the first current peak. The extra voltage stress from this solution is mitigated by negative coupling. The passive components (resistance, self-inductance, and mutual inductance) are determined by an equation involving the magnitude of Vth mismatch, current rise time, and unbalance percentage. The influence of other parasitic inductances on current sharing is analyzed. The robustness of this passive balancing method is experimentally verified by a prototype with a significant amount of parasitic inductances. Test results show that the difference of peak currents can be reduced from 15% to 3% without changing the switching loss and voltage stress. Auteurs: Yincan Mao;Zichen Miao;Chi-Ming Wang;Khai D. T. Ngo; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 8334 - 8343 Editeur: IEEE Document complet vers site de l'éditeur

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