#### Electrical and Electronics Engineering publications abstract of: 10-2017 sorted by title, page: 2

» A Novel Stator Structure for Active Axial Force Improvement in a One-Axis Actively Positioned Single-Drive Bearingless Motor
 Abstract:This paper presents a novel stator structure in an actively positioned bearingless motor with 1-degree of freedom. The single-drive bearingless motor concept has been adapted so that the torque and active axial force are regulated independently by the q- and d-axis currents, respectively, with only one three-phase inverter. The axial z-axis position is actively regulated, but the other axes (i.e., the radial and tilting movements) are passively stabilized. A novel stator structure has been proposed to enhance the active axial force. The stator is designed with soft magnetic composites. Experiments confirmed that the active axial force is enhanced by 50%. Autors: Hiroya Sugimoto;Itsuki Shimura;Akira Chiba; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4414 - 4421 Publisher: IEEE
» A Novel Symmetric Double-Slot Structure for Antipodal Vivaldi Antenna to Lower Cross-Polarization Level
 Abstract:An antipodal Vivaldi antenna (AVA) with novel symmetric two-layer double-slot structure is proposed. When excited with equiamplitude and opposite phase, the two slots will have the sum vector of their E-field vectors parallel to the antenna’s plane, which is uniform to the E-field vector in the slot of a balanced AVA with three-layer structure. Compared with a typical AVA with the same size, the proposed antenna has better impedance characteristics because of the amelioration introduced by the coupling between the two slots, as well as the more symmetric radiation patterns and the remarkably lowered cross-polarization level at the endfire direction. For validating the analysis, an UWB balun based on the double-sided parallel stripline is designed for realizing the excitation, and a sample of the proposed antenna is fabricated. The measured results reveal that the proposed has an operating frequency range from 2.8 to 15 GHz, in which the cross-polarization level is less than −24.8 dB. Besides, the group delay of two face-to-face samples has a variation less than 0.62 ns, which exhibits the ability of the novel structure for transferring pulse signal with high fidelity. The simple two-layer structure, together with the improvement both in impedance and radiation characteristics, makes the proposed antenna much desirable for the UWB applications. Autors: Ya-Wei Wang;Zhong-Wu Yu; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5599 - 5604 Publisher: IEEE
» A Novel TD-VIE Based on MOT Scheme for Analysis of Dispersive Objects
 Abstract:A novel time-domain volume integral equation (TD-VIE) is proposed to analyze the transient electromagnetic scattering from inhomogeneous dispersive objects. In this TD-VIE method, the higher order Nyström method is applied in spatial domain. Namely, the curvilinear tetrahedron elements are utilized to discretize dielectric objects and resulting unknowns are volume electric current density. The Lagrange interpolation polynomials are used to represent spatial basis functions. In temporal domain, the marching-on-in-time (MOT) scheme is applied and the shifted Lagrange interpolation functions are used to represent temporal basis functions. Moreover, the point-matching method is applied both in spatial and temporal domain. Compared with the traditional spatial Schaubert–Wilton–Glisson basis based on TD-VIE, this novel TD-VIE method is more efficient. Several numerical examples have demonstrated that the proposed method is accurate, stable, and also more efficient than the traditional TD-VIE. Autors: Shifei Tao;Jun Cao;Zhenhong Fan;R. S. Chen; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5387 - 5395 Publisher: IEEE
» A Novel Thermomagnetic-Actuated Gripper With a Piezoelectric–Pyroelectric Sensing Readout of Gripping States and Forces
 Abstract:In this paper, we reported a thermomagnetic-actuated gripper with a piezoelectric–pyroelectric sensing readout of gripping states and forces. The gripper consists of two CuBe cantilever beams, a Gd sheet, NdFeB hard magnets, a thermoelectric generator (TEG), a piezoelectric–pyroelectric PZT sheet, and a polymer-polymethyl methacrylate base. When TEG cools the Gd sheet lower than its Curie temperature, the magnetic attraction between the Gd sheet and the NdFeB magnets is produced due to the thermomagnetic property of the Gd sheet. Subsequently, the magnetic attractive force deflects two beams until beams contact to each other. Thus, the gripper can grasp a small object. Furthermore, when the gripper is operated to grasp the object, the piezoelectric–pyroelectric PZT sheet of the gripper produces voltage response. Through analyzing the voltage response, the gripping state is detected and subsequently the gripping force is obtained. After gripping, a negative dc current is applied to TEG to heat the Gd sheet higher than Gd’s Curie temperature. Due to this, the magnetic attractive force is reduced and eventually eliminated. Consequently, the beams are separated due to their spring-back force. Thus, the gripper releases the object. The experimental results show that the gripper can be sequentially operated to grasp and release the object. Furthermore, as the current applied to the TEG is increased, the gripping force is increased. The maximum gripping force of the gripper is 0.69 N when a dc current of 0.7 A is applied. Moreover, when comparing conventional magnetic-field-actuated magnetic grippers, our gripper can be individually operated by applied currents, detect the gripping state, and sense the gripping force. Autors: Chin-Chung Chen;Tien-Kan Chung;Chu-Yi Lin; Appeared in: IEEE Transactions on Magnetics Publication date: Oct 2017, volume: 53, issue:10, pages: 1 - 16 Publisher: IEEE
» A Novel Trail Detection and Scene Understanding Framework for a Quadrotor UAV With Monocular Vision
 Abstract:Vision-based trail detection and autonomous scene understanding play a key role for unmanned aerial vehicles (UAVs) working in complex outdoor environments such as isolated disaster sites. This paper investigates the problems associated with trail detection and tracking, as well as autonomous scene understanding using a quadrotor UAV. A framework that integrates support vector machine-based trail detection with a trail tracker is proposed to accomplish trail direction estimation and tracking at a low cost of computation and in real time. To accurately perform online parameter estimation, a performance test is designed and implemented to evaluate the accuracy. Moreover, the simple linear iterative clustering superpixel segmentation algorithm is utilized in the proposed system framework to guarantee the scene segmentation accuracy. Visual detection for significant objects or people is implemented by using single shot multibox detector algorithm. A series of experiments are conducted by using a quadrotor platform DJI M100 and experimental results show the validity and practicality of the proposed approach. Autors: Yisha Liu;Qunxiang Wang;Yan Zhuang;Huosheng Hu; Appeared in: IEEE Sensors Journal Publication date: Oct 2017, volume: 17, issue:20, pages: 6778 - 6787 Publisher: IEEE
» A Novel Tri-Band Wilkinson Power Divider for Multiband Wireless Applications
 Abstract:This letter presents a novel and simple technique for the design of an arbitrary tri-band Wilkinson power divider. The proposed technique is based on the use of quarter-wave open stubs (QWOS) at the desired operation frequencies, placed at appropriate positions along the divider’s 50- output transmission lines, to create the targeted tri-band response. These stubs present a high impedance at the frequencies of interest, while introducing transmission zeroes between the operation bands. For a compact design, slow-wave structure has been adopted to miniaturize the conventional divider’s arms. To validate the above concept, a power divider—intended to operate in the 1.5-, 1.9-, and 2.35-GHz frequency bands—is designed. The results of the fabricated circuit present low insertion loss of less than 0.45 dB while offering an isolation better than 15 dB in the three bands of operation. Compared to recently published results, the proposed divider exhibits the largest fractional bandwidth at each operation frequency. Furthermore, it can be easily extended to more bands by adding QWOS depending on the required number of bands. Autors: Basem M. Abdelrahman;Hesham N. Ahmed;A. I. Nashed; Appeared in: IEEE Microwave and Wireless Components Letters Publication date: Oct 2017, volume: 27, issue:10, pages: 891 - 893 Publisher: IEEE
» A Novel Utilization of Image Registration Techniques to Process Mastcam Images in Mars Rover With Applications to Image Fusion, Pixel Clustering, and Anomaly Detection
 Abstract:The Mars Science Laboratory is a robotic rover mission to Mars launched by NASA on November 26, 2011, which successfully landed the Curiosity rover in Gale Crater on August 6, 2012. The Curiosity rover has two mast cameras (Mastcams) that acquire stereo images at a number of different wavelengths. Each camera has nine bands of which six bands are overlapped in the two cameras. These acquired stereo band images at different wavelengths can be fused into a 12-band multispectral image cube, which could be helpful to guide the rover to interesting locations. Since the two Mastcams’ fields of view are three times different from each other, in order to fuse the left- and right-camera band images to form a multispectral image cube, there is a need for a precise image alignment of the stereo images with registration errors at the subpixel level. A two-step image alignment approach with a novel utilization of existing image registration algorithms is introduced in this paper and is applied to a set of Mastcam stereo images. The effect of the two-step alignment approach using more than 100 pairs of Mastcam images, selected from over 500000 images in NASA's Planetary Data System database, clearly demonstrated that the fused images can improve pixel clustering and anomaly detection performance. In particular, registration errors in the subpixel level are observed with the applied alignment approach. Moreover, the pixel clustering and anomaly detection performance have been observed to be better when using fused images. Autors: Bulent Ayhan;Minh Dao;Chiman Kwan;Hua-Mei Chen;James F. Bell;Richard Kidd; Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Publication date: Oct 2017, volume: 10, issue:10, pages: 4553 - 4564 Publisher: IEEE
» A Novel Variable Flux Memory Machine With Series Hybrid Magnets
 Abstract:This paper proposes a novel variable flux memory (VFM) machine, in which the “constant” permanent magnet (CPM) with high coercive force and the “variable” PM (VPM) with low coercive force are alternatively located in the interior-PM rotor. Thus, the VPMs and CPMs are magnetically connected in series, with which the CPMs can assist the VPMs to withstand the unintentional demagnetization caused by armature reaction. Therefore, a high armature current can be applied to the machine. Meanwhile, the reluctance torque is retrieved. Thus, a high torque density can be obtained. Based on two-dimensional finite element analysis, first, the electromagnetic performance of the proposed VFM machine in two extreme magnetization states is evaluated in detail. Then, the demagnetization and remagnetization characteristics are investigated, in which the working points of VPMs are illustrated. Furthermore, the advantages of improved efficiency of the proposed VFM machine are demonstrated. A prototype machine is manufactured and tested to validate the predictions. Autors: Hao Hua;Z. Q. Zhu;Adam Pride;Rajesh P. Deodhar;Toshinori Sasaki; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4396 - 4405 Publisher: IEEE
» A Numerical Approach to Stability of Multiclass Queueing Networks
 Abstract:The multiclass queueing network (McQN) arises as a natural multiclass extension of the traditional (single-class) Jackson network. In a single-class network, subcriticality (i.e., subunitary nominal workload at every station) entails stability, but this is no longer sufficient when jobs/customers of different classes (i.e., with different service requirements and/or routing scheme) visit the same server; therefore, analytical conditions for stability of McQNs are lacking, in general. In this note, we design a numerical (simulation-based) method for determining the stability region of a McQN, in terms of arrival rate(s). Our method exploits certain (stochastic) monotonicity properties enjoyed by the associated Markovian queue-configuration process. Stochastic monotonicity is a quite common feature of queueing models and can be easily established in the single-class framework (Jackson networks); recently, also for a wide class of McQNs, including first-come-first-serve networks, monotonicity properties have been established. Here, we provide a minimal set of conditions, under which the method performs correctly. Eventually, we illustrate the use of our numerical method by presenting a set of numerical experiments, covering both single- and multiclass networks. Autors: Haralambie Leahu;Michel Mandjes;Ana-Maria Oprescu; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5478 - 5484 Publisher: IEEE
» A Parametric Model Approach for Structural Reconstruction of Scale-Free Networks
 Abstract:We propose a parametric network generation model which we call network reconstruction model (NRM) for structural reconstruction of scale-free real networks with power-law exponent greater than 2 in the tail of its degree distribution. The reconstruction method for a real network is concerned with finding the optimal values of the model parameters by utilizing the power-law exponents of model network and the real network. The method is validated for certain real world networks. The usefulness of NRM in order to solve structural reconstruction problem is demonstrated by comparing its performance with some existing popular network generative models. We show that NRM can generate networks which follow edge-densification and densification power-law when the model parameters satisfy an inequality. Computable expressions of the expected number of triangles and expected diameter are obtained for model networks generated by NRM. Finally, we numerically establish that NRM can generate networks with shrinking diameter and modular structure when specific model parameters are chosen. Autors: Pradumn Kumar Pandey;Bibhas Adhikari; Appeared in: IEEE Transactions on Knowledge and Data Engineering Publication date: Oct 2017, volume: 29, issue:10, pages: 2072 - 2085 Publisher: IEEE
» A Participatory Urban Traffic Monitoring System: The Power of Bus Riders
 Abstract:This paper presents a participatory sensing-based urban traffic monitoring system. Different from existing works that heavily rely on intrusive sensing or full cooperation from probe vehicles, our system exploits the power of participatory sensing and crowdsources the traffic sensing tasks to bus riders’ mobile phones. The bus riders are information source providers and, meanwhile, major consumers of the final traffic output. The system takes public buses as dummy probes to detect road traffic conditions, and collects the minimum set of cellular data together with some lightweight sensing hints from the bus riders’ mobile phones. Based on the crowdsourced data from participants, the system recovers the bus travel information and further derives the instant traffic conditions of roads covered by bus routes. The real-world experiments with a prototype implementation demonstrate the feasibility of our system, which achieves accurate and fine-grained traffic estimation with modest sensing and computation overhead at the crowd. Autors: Zhidan Liu;Shiqi Jiang;Pengfei Zhou;Mo Li; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Oct 2017, volume: 18, issue:10, pages: 2851 - 2864 Publisher: IEEE
» A Physical Surface Roughness Model and Its Applications
 Abstract:This paper covers the essential aspects of modeling surface roughness for microwave applications based on underlying physics. After a short summary of the relevant field theoretical fundamentals, surface roughness metrology and commonly used roughness parameters are described. Existing models and their limitations are discussed before the recently proposed Gradient Model is introduced. To this purpose, the modeling approach, the derivation from Maxwell’s equations, model predictions, and their experimental verification are shown. Reasonable choices for effective material parameters reflecting the electromagnetic effects of surface roughness as well as a corresponding surface impedance concept are derived. Both concepts allow for easy application of the Gradient Model with 3-D field solvers or analytical models. The obtained simulation results illustrate roughness impact on loss and phase delay in typical transmission lines. Comparison to measurement results up to 100 GHz shows that the Gradient Model accurately predicts these quantities for rough conductor surfaces. As it is not limited to transmission lines only, it significantly improves the design process for arbitrary microwave applications with 3-D field solvers for this frequency range. Autors: Gerald Gold;Klaus Helmreich; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Oct 2017, volume: 65, issue:10, pages: 3720 - 3732 Publisher: IEEE
» A Post-Swirl Maneuvering Propulsor Application to Undersea Vehicles
 Abstract:A method to generate vehicle maneuvering forces from a propulsor alone has been applied to a generic undersea vehicle. Open and ducted post-swirl propulsors were configured with an upstream rotor and downstream stator row. During normal operation, the downstream stator blades are all situated at the same pitch angle and generate a roll moment to counter the torque produced by the rotor. By varying the pitch angles of the stator blade about the circumference, it is possible to generate a mean stator side force that can be used to maneuver the vehicle. In addition, the side force can be increased with increasing thrust producing side forces at very low vehicle velocities enabling low-speed maneuvering capability. The viscous, 3-D Reynolds-averaged Navier–Stokes (RANS) commercial code Fluent was used to predict the vehicle and propulsor component forces as well as the velocity field. Open and ducted geometric configurations were studied and force coefficients computed and compared with currently used control surface forces. Computations predicted that the maneuvering propulsor generated side forces equivalent to those produced by conventional control surfaces with side force coefficients on the order of 0.25 for the open propulsor at the self-propulsion point. This translates to 50% larger forces than can be generated by conventional control surfaces on 21 unmanned undersea vehicles. The ducted configuration produces maximum side force coefficients on the order of 0.15, which is still sufficient for vehicle control. Both configurations produced side forces for the Bollard pull condition indicating low-speed maneuvering capability. Autors: Stephen A. Huyer; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Oct 2017, volume: 42, issue:4, pages: 770 - 781 Publisher: IEEE
» A Power Control and Anticolision Mechanism for RFID Systems
 Abstract:RFID (Radio Frequency IDentification) applications require identification of large number of tags, which results in increased collisions and degradation in the performance of traditional DFSA (Dynamic Frame slot ALOHA) algorithms. This paper proposes a power control mechanism to estimate the amount of tags in RFID networks. The mechanism is based on the division of the interrogation zone in sub-areas called clusters. This division is used to interrogate in a single slot all tags of a cluster, perform measurements of RSSI and, with it, estimate the amount of tags per cluster. The mechanism is simulated and evaluated using our own simulator developed in C/C ++ programming language. We compared the results of number of slots, identification time and energy consumption with that obtained from the use of the optimal DFSA algorithm and Q algorithm of the EPCglobal standard. From the simulation results, one can see that the proposed mechanism provides performance 99% close to the ideal DFSA in dense networks, where there are large amount of tags. Autors: Walfredo Costa Lucena Filho;Lucas Carvalho Cordeiro;Waldir Sabino da Silva Junior;Celso Barbosa Carvalho; Appeared in: IEEE Latin America Transactions Publication date: Oct 2017, volume: 15, issue:10, pages: 1933 - 1940 Publisher: IEEE
» A Power-Packed Issue
 Abstract:Welcome to the power and energy theme issue of IEEE Potentials. The following four articles will address highimpact topics in the world of power systems, written by energy experts from both industry and academia. I hope you enjoy reading them and gain a greater insight into this exciting field. Autors: Edvina Uzunovic;Juan Carlos Montero Quiros; Appeared in: IEEE Potentials Publication date: Oct 2017, volume: 36, issue:5, pages: 6 - 7 Publisher: IEEE
» A Preventive Approach for Solving Battery Imbalance Issue by Using a Bidirectional Multiple-Input Ćuk Converter Working in DCVM
 Abstract:State of charge (SoC) imbalance among batteries in a battery energy storage system (BESS) degrades the system performance and may lead to safety issue. A bidirectional multiple-input Ćuk converter for the BESS is proposed to prevent batteries from SoC imbalance issue. Compared to the traditional BESS, the battery balancing and voltage/current regulation subsystems are combined into one. As a result, the overall system complexity is significantly reduced. Moreover, the current flow of each battery is self-adjusted according to its terminal voltage. Therefore, the system does not require sophisticated control algorithm for battery balancing. Moreover, the proposed system has no energy dumping and energy transferring between batteries, which avoids unnecessary energy lose. Due to the nature of multiple-input converter structure, the proposed system can handle certain component failure. The proposed approach of designing the BESS has been investigated through simulation and validated experimentally. Autors: Jian Qi;Dylan Dah-Chuan Lu; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 7780 - 7789 Publisher: IEEE
» A Prototype Therapy System for Transcutaneous Application of Boiling Histotripsy
 Abstract:Boiling histotripsy (BH) is a method of focused ultrasound surgery that noninvasively applies millisecond-length pulses with high-amplitude shock fronts to generate liquefied lesions in tissue. Such a technique requires unique outputs compared to a focused ultrasound thermal therapy apparatus, particularly to achieve high in situ pressure levels through intervening tissue. This paper describes the design and characterization of a system capable of producing the necessary pressure to transcutaneously administer BH therapy through clinically relevant overlying tissue paths using pulses with duration up to 10 ms. A high-voltage electronic pulser was constructed to drive a 1-MHz focused ultrasound transducer to produce shock waves with amplitude capable of generating boiling within the pulse duration in tissue. The system output was characterized by numerical modeling with the 3-D Westervelt equation using boundary conditions established by acoustic holography measurements of the source field. Such simulations were found to be in agreement with directly measured focal waveforms. An existing derating method for nonlinear therapeutic fields was used to estimate in situ pressure levels at different tissue depths. The system was tested in ex vivo bovine liver samples to create BH lesions at depths up to 7 cm. Lesions were also created through excised porcine body wall (skin, adipose, and muscle) with 3–5 cm thickness. These results indicate that the system is capable of producing the necessary output for transcutaneous ablation with BH. Autors: Adam D. Maxwell;Petr V. Yuldashev;Wayne Kreider;Tatiana D. Khokhlova;George R. Schade;Timothy L. Hall;Oleg A. Sapozhnikov;Michael R. Bailey;Vera A. Khokhlova; Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control Publication date: Oct 2017, volume: 64, issue:10, pages: 1542 - 1557 Publisher: IEEE
» A pyrrhic victory for nuclear power [News]
 Abstract:By late this year or early in 2018, two nuclear reactors could start operating in China-an event that might be a lifesaver for the units' crippled builder and designer, Westinghouse Electric Co., and for the technology they represent. Both Westinghouse and its prized AP1000 reactor design have suffered a series of humbling setbacks this year. The AP1000 is arguably the world's most advanced commercial reactor. It is designed to passively cool itself during an accidental shutdown, theoretically avoiding accidents like those at Ukraine's Chernobyl power plant and Japan's Fukushima Daiichi. And for over a decade, it has been the presumed successor to China's mainstay reactors, which employ a 1970s-era French design. Autors: Peter Fairley; Appeared in: IEEE Spectrum Publication date: Oct 2017, volume: 54, issue:10, pages: 11 - 12 Publisher: IEEE
» A Q-Band Low-Profile Dual Circularly Polarized Array Antenna Incorporating Linearly Polarized Substrate Integrated Waveguide-Fed Patch Subarrays
 Abstract:An integrated low-profile dual circularly polarized (dual CP) array antenna operating in the Q-band is proposed in this paper, which is realized by sequentially rotating subarrays comprised linearly polarized (LP) substrate integrated waveguide (SIW)-fed patches. The design methodology and working mechanism of the LP SIW-fed patches is presented first, which is implemented with a two-layer printed circuit board structure where the SIW feeding network is located in the bottom substrate and the patches are on the top substrate. Four subarrays are then arranged according to the requirements of a sequential rotation array for producing CP directive beams. A two-layer SIW feeding network for providing the required amplitude and phase distributions for the four subarrays is designed, which includes two input ports for exciting CP radiation with opposite handedness, respectively. Prototypes of the LP subarray and the integrated dual CP array antenna were fabricated and measured. Good agreement between the simulation and measured results validates the designs. The proposed low-cost and lightweight dual CP antenna owns the advantages of wide useful bandwidth (8.9%), high isolation of more than 19 dB, low profile of less than , and good orthogonal polarization discrimination higher than 25 dB. Autors: Jun Xu;Wei Hong;Zhi Hao Jiang;Jixin Chen;Hui Zhang; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5200 - 5210 Publisher: IEEE
» A Q-Slot Monopole for UWB Body-Centric Wireless Communications
 Abstract:This paper presents a novel and simple ultrawideband printed rectangular monopole antenna for body-centric wireless communications. The design is based on etching a Q-slot on a rectangular radiator and is optimized to produce the largest bandwidth in free space and close to the human body. We analyze the design of the proposed antenna and assess its performance in terms of bandwidth, gain, efficiency, and radiation patterns. We also characterize the antenna in the time-domain by calculating its fidelity factor. Our results show that the Q-slot antenna maintains its bandwidth when placed in close contact with the human body, or in contact with breast-mimicking tissue phantoms. The very good agreement between the calculated and measured antenna performances in free space and on body suggests that the antenna is immune to variations in the human tissue and is also robust to fabrication tolerances. Autors: Bright Yeboah-Akowuah;Panagiotis Kosmas;Yifan Chen; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5069 - 5075 Publisher: IEEE
» A Quasi-Resonant Switched-Capacitor Multilevel Inverter With Self-Voltage Balancing for Single-Phase High-Frequency AC Microgrids
 Abstract:In this paper, a quasi-resonant switched-capacitor (QRSC) multilevel inverter (MLI) is proposed with self-voltage balancing for single-phase high-frequency ac (HFAC) microgrids. It is composed of a QRSC circuit (QRSCC) in the frontend and an H-bridge circuit in the backend. The input voltage is divided averagely by the series-connected capacitors in QRSCC, and any voltage level can be obtained by increasing the capacitor number. The different operational mechanism and the resulting different application make up for the deficiency of the existing switched-capacitor topologies. The capacitors are connected in parallel partially or wholly when discharging to the load, thus the self-voltage balancing is realized without any high-frequency balancing algorithm. In other words, the proposed QRSC MLI is especially adapted for HFAC fields, where fundamental frequency modulation is preferred when considering the switching frequency and the resulting loss. The quasi-resonance technique is utilized to suppress the current spikes that emerge from the instantaneous parallel connection of the series-connected capacitors and the input source, decreasing the capacitance, increasing their lifetimes, and reducing the electromagnetic interference, simultaneously. The circuit analysis, power loss analysis, and comparisons with typical switched-capacitor topologies are presented. To evaluate the superior performances, a nine-level prototype is designed and implemented in both simulation and experiment, whose results confirm the feasibility of the proposed QRSC MLI. Autors: Jun Zeng;Jialei Wu;Junfeng Liu;Huafang Guo; Appeared in: IEEE Transactions on Industrial Informatics Publication date: Oct 2017, volume: 13, issue:5, pages: 2669 - 2679 Publisher: IEEE
» A Randomized Approach to Probabilistic Footprint Estimation of a Space Debris Uncontrolled Reentry
 Abstract:This paper studies the problem of characterizing the region of the airspace that will be occupied by a space debris during an uncontrolled reentry (footprint), with the final goal of supporting the air traffic controllers in their task of guiding aircraft safely from their origin to their destination. Given the various sources of uncertainty affecting the debris dynamics, the reentry process is characterized probabilistically and the problem of determining the footprint is formulated in terms of a chance-constrained optimization program, which is solved via a simulation-based method. When observations of the debris initial position and radar measurements of the aircraft prior to the reentry event are available, nonlinear filtering techniques can be adopted and the posterior probability distribution of the debris position as well as of the wind field affecting the reentry process can be integrated in the chance-constraint formulation so as to obtain an enhanced estimate of the footprint. Simulation results show the efficacy of the approach. Autors: Alessandro Falsone;Maria Prandini; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Oct 2017, volume: 18, issue:10, pages: 2657 - 2666 Publisher: IEEE
» A Resonant ZVZCS DC–DC Converter With Two Uneven Transformers for an MVDC Collection System of Offshore Wind Farms
 Abstract:A resonant zero-voltage and zero-current-switching (ZVZCS) dc-dc converter is proposed in this paper for a medium-voltage dc collection system of offshore wind farms. The resonant converter is composed of two full-bridge cells sharing a bridge leg, two transformers with uneven power ratings and different functions, whose secondary windings are connected in series and a voltage-doubler rectifier. The converter operates in discontinuous current mode and can achieve zero-current switching for four main power switches and rectifier diodes over the whole load range. The two auxiliary switches with small forward current can be turned on with ZVZCS, and turned off with zero-voltage switching. Hence, the switching loss can be reduced and efficiency is improved. The operation principle of the converter is analyzed and design rules of main parameters are presented. The influences of the turn ratios of auxiliary transformer and resonant capacitance on the peak and switching-off currents are discussed in detail. Furthermore, a model is built in PLECS and simulation results are given. A 150-1500 V/2 kW prototype is established and tested to verify the operation principle and design rules. Autors: Liangcai Shu;Wu Chen;Guangfu Ning;Wu Cao;Jun Mei;Jianfeng Zhao;Chun Liu;Guoqing He; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 7886 - 7895 Publisher: IEEE
» A Resource-Limited Hardware Accelerator for Convolutional Neural Networks in Embedded Vision Applications
 Abstract:In this brief, we introduce an architecture for accelerating convolution stages in convolutional neural networks (CNNs) implemented in embedded vision systems. The purpose of the architecture is to exploit the inherent parallelism in CNNs to reduce the required bandwidth, resource usage, and power consumption of highly computationally complex convolution operations as required by real-time embedded applications. We also implement the proposed architecture using fixed-point arithmetic on a ZC706 evaluation board that features a Xilinx Zynq-7000 system on-chip, where the embedded ARM processor with high clocking speed is used as the main controller to increase the flexibility and speed. The proposed architecture runs under a frequency of 150 MHz, which leads to 19.2 Giga multiply accumulation operations per second while consuming less than 10 W in power. This is done using only 391 DSP48 modules, which shows significant utilization improvement compared to the state-of-the-art architectures. Autors: Shayan Moini;Bijan Alizadeh;Mohammad Emad;Reza Ebrahimpour; Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs Publication date: Oct 2017, volume: 64, issue:10, pages: 1217 - 1221 Publisher: IEEE
» A Review of On-Chip Micro Supercapacitors for Integrated Self-Powering Systems
 Abstract:Miniaturized self-powering systems that integrate both energy harvesters and energy storage units as the power sources are essential to realize maintenance-free wireless sensor networks, implantable medical devices, and active radio frequency identification systems. On-chip micro supercapacitors (MSCs) are promising candidates for energy storage in such systems by providing high power densities, fast charge/discharge rates, and long cycle life. Researchers have been improving the performances, especially energy and power densities, of MSCs in recent years. This paper reviews the fundamental working mechanisms and design considerations of on-chip MSCs with special emphasis on the advantages of 3-D configurations. Typical fabrication methods are summarized, and their effects on the device performance and system integration are analyzed. In particular, the power generation of micro energy harvesters and the power consumption of typical wireless micro systems are surveyed, providing the basic and targeting performance requirements of future MSCs that can be integrated with them. [2017-0069] Autors: Caiwei Shen;Sixing Xu;Yingxi Xie;Mohan Sanghadasa;Xiaohong Wang;Liwei Lin; Appeared in: Journal of Microelectromechanical Systems Publication date: Oct 2017, volume: 26, issue:5, pages: 949 - 965 Publisher: IEEE
» A Robust Active Damping Control Strategy for an $LCL$ -Based Grid-Connected DG Unit
 Abstract:The connection of a distributed generation (DG) unit to a weak power system is challenging due to stability issues resulted from dynamic interactions between the DG unit and the grid. An LCL-based DG unit is a particularly challenging case due to the presence of a high resonant peak in its frequency response. This paper proposes a robust control strategy to overcome the stability issues of an LCL-based DG unit connected to a weak grid. The main advantage of the proposed control strategy is that it guarantees stability and satisfactory transient performance against the variations of grid impedance. Moreover, it is able to decouple the d and q channels of the control system, which enables independent regulation of the real and reactive output power of the DG unit. Real-time simulations and experimental tests illustrate the effectiveness of the proposed controller in terms of improved transient performance, robust stability, and satisfactory controller set-point tracking. Autors: Mahdieh S. Sadabadi;Aboutaleb Haddadi;Houshang Karimi;Alireza Karimi; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8055 - 8065 Publisher: IEEE
» A Robust Detection Method of Control Points for Calibration and Measurement With Defocused Images
 Abstract:This paper presents a detection method of control points for the camera calibration and measurement applications, which is robust to defocus. Our method is based on a ground truth, which we call ridge invariance. That is, the positions of broad-brush lines’ ridge lines are invariant to defocus blur. First, the ridge invariance is deduced in theory. Then, the methods for ridge point’s detection including defocus degree estimation and salience enhancement are deduced. In calibration and measurement experiments, new marks are designed and control points are determined at intersects of the ridge curves. Experiments show that our method can obtain precise calibration and measurement results with images in a large defocus amount range. In the effective defocus amount range, the accuracy of the proposed method almost keeps unchanged to the best values. The proposed method has approximated the same performance as conventional methods at good focus values. Autors: Wendong Ding;Xilong Liu;De Xu;Dapeng Zhang;Zhengtao Zhang; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Oct 2017, volume: 66, issue:10, pages: 2725 - 2735 Publisher: IEEE
» A Robust Event-Triggered Approach for Fast Sampled-Data Extremization and Learning
 Abstract:This paper presents a general framework for the analysis and design of a class of model-free, robust, and efficient sampled-data-based algorithms for extremization and learning in continuous-time nonlinear systems that generate response maps with an optimal operational set. In particular, we consider plants described by differential inclusions, interconnected in a sampled-data setting with a robust learning algorithm characterized by a constrained difference inclusion. In contrast to standard sampled-data-based approaches, where the learning dynamics are updated after a fixed sufficiently long sampling time has passed, we design a robust dynamic event-based mechanism that triggers the control action as soon as the rate of change of the output of the plant is sufficiently small. By using this event-based update rule, a significant improvement in the convergence time of the closed-loop system can be achieved. Using the framework of set-valued hybrid dynamical systems, we establish for the closed-loop system the existence of a uniformly asymptotically stable compact set, which, by an appropriate tuning of the control parameters, can be made arbitrarily close to the optimal operational set. Our results generalize existing results for periodic sampled-data extremum seeking, and can be used to solve model-free multivariable smooth/nonsmooth constrained optimization problems, as well as learning problems in game theoretical scenarios. Autors: Jorge I. Poveda;Andrew R. Teel; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 4949 - 4964 Publisher: IEEE
» A Robust Flywheel Energy Storage System Discharge Strategy for Wide Speed Range Operation
 Abstract:Wide speed range operation in discharge mode is essential for ensuring discharge depth and energy storage capacity of a flywheel energy storage system (FESS). However, for a permanent magnet synchronous motor/generator-based FESS, the wide-range speed variation in a short discharge period causes consecutive decreases in ac voltage frequency and amplitude. As a result, operation point shift leads to performance deterioration of the conventional local linearization based dc-link voltage control strategies. This study aims to realize a consistent robust discharge performance within the entire available operation range for FESS. We propose a robust discharge strategy that incorporates the speed variation to the dc-link voltage controller. A speed-dependent extended state observer is designed to realize global linearization and enhance the robustness. A speed adaptive feedback control law is designed to ensure consistent dynamic performance within the entire available operation range. Finally, the discharge strategy is validated at different speeds on a high-speed FESS test bench. Autors: Xiang Zhang;Jiaqiang Yang; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 7862 - 7873 Publisher: IEEE
» A Robust Translational Motion Compensation Method for ISAR Imaging Based on Keystone Transform and Fractional Fourier Transform Under Low SNR Environment
 Abstract:In this work, a parametric-based approach is proposed to perform joint range alignment and phase adjustment based on the intention of fully exploiting the energy of all the scatterers in the moving target and the two-dimensional coherent accumulation gain of both range and azimuth compressions. To that end, first, translational motion is modeled as a polynomial signal, and inspired by the fact that all the scatterers in the moving target experience the same translational range history, the phase difference operation and keystone transform (KT) are utilized to transform the energy of all the scatterers into one range cell. Second, by the virtue of the fractional Fourier transform (FrFT), the energy of all the scatterers is coherently accumulated into a peak point, and from which the polynomial coefficients can be obtained accurately. With the estimated polynomial coefficients, the dechirp operation and KT are applied jointly to compensate range misalignment and phase error. The analysis of the proposed method shows that it is of low computational complexity due to avoiding multidimensional search and improves the output SNR providing satisfactory low SNR performance. The experimental results are provided to demonstrate the performance of the proposed method compared with the state-of-the-art algorithms. Autors: Dong Li;Muyang Zhan;Hongqing Liu;Yong Liao;Guisheng Liao; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2140 - 2156 Publisher: IEEE
» A Scalable Framework for Wireless Distributed Computing
 Abstract:We consider a wireless distributed computing system, in which multiple mobile users, connected wirelessly through an access point, collaborate to perform a computation task. In particular, users communicate with each other via the access point to exchange their locally computed intermediate computation results, which is known as data shuffling. We propose a scalable framework for this system, in which the required communication bandwidth for data shuffling does not increase with the number of users in the network. The key idea is to utilize a particular repetitive pattern of placing the data set (thus a particular repetitive pattern of intermediate computations), in order to provide the coding opportunities at both the users and the access point, which reduce the required uplink communication bandwidth from users to the access point and the downlink communication bandwidth from access point to users by factors that grow linearly with the number of users. We also demonstrate that the proposed data set placement and coded shuffling schemes are optimal (i.e., achieve the minimum required shuffling load) for both a centralized setting and a decentralized setting, by developing tight information-theoretic lower bounds. Autors: Songze Li;Qian Yu;Mohammad Ali Maddah-Ali;A. Salman Avestimehr; Appeared in: IEEE/ACM Transactions on Networking Publication date: Oct 2017, volume: 25, issue:5, pages: 2643 - 2654 Publisher: IEEE
» A Seaglider-Integrated Digital Monitor for Bioacoustic Sensing
 Abstract:An acoustic Digital MONitor (DMON) has been integrated into a Seaglider autonomous underwater vehicle to serve as a general-use tool for passive acoustic sensing of marine mammal vocalizations. The system is being developed as a complement to conventional ship-based cetacean survey methods. The acoustic system includes three omnidirectional hydrophones, one located on centerline of the aft payload hatch and one on each wingtip. An onboard real-time detector has been implemented to record an audio sample if ambient noise has risen above a user-prescribed signal-to-noise ratio (SNR) threshold level. The data size and the number of detections are available in semi-real time, and the acoustic data are retrieved upon recovery of the instrument. Because the DMON system interfaces with the Seaglider firmware, the glider pilot has the capability to modify several operational parameters governing the collection of acoustic data while the glider is deployed to tailor the data recording to the desired mission objectives. This implementation is referred to as the Seaglider Customizable Sampling Configuration (SCSC) DMON and has recorded a wide variety of cetacean vocal activity offshore the Hawaiian Islands. Autors: Lora J. Van Uffelen;Ethan H Roth;Bruce M. Howe;Erin M. Oleson;Yvonne Barkley; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Oct 2017, volume: 42, issue:4, pages: 800 - 807 Publisher: IEEE
» A Self-Adaptive Capacitive Compensation Technique for Body Channel Communication
 Abstract:In wireless body area network, capacitive-coupling body channel communication (CC-BCC) has the potential to attain better energy efficiency over conventional wireless communication schemes. The CC-BCC scheme utilizes the human body as the forward signal transmission medium, reducing the path loss in wireless body-centric communications. However, the backward path is formed by the coupling capacitance between the ground electrodes (GEs) of transmitter (Tx) and receiver (Rx), which increases the path loss and results in a body posture dependent backward impedance. Conventional methods use a fixed inductor to resonate with the backward capacitor to compensate the path loss, while it's not effective in compensating the variable backward impedance induced by the body movements. In this paper, we propose a self-adaptive capacitive compensation (SACC) technique to address such a problem. A backward distance detector is introduced to estimate the distance between two GEs of Tx and Rx, and a backward capacitance model is built to calculate the backward capacitance. The calculated backward capacitance at varying body posture is compensated by a digitally controlled tunable inductor (DCTI). The proposed SACC technique is validated by a prototype CC-BCC system, and measurements are taken on human subjects. The measurement results show that 9dB–16 dB channel enhancement can be achieved at a backward path distance of 1 cm-10 cm. Autors: Jingna Mao;Huazhong Yang;Yong Lian;Bo Zhao; Appeared in: IEEE Transactions on Biomedical Circuits and Systems Publication date: Oct 2017, volume: 11, issue:5, pages: 1001 - 1012 Publisher: IEEE
» A Self-Calibrated Cryogenic Current Cell for 4.2 K Current Steering D/A Converters
 Abstract:This brief presents a cryogenic CMOS unit current cell operating from room temperature down to 4.2 K, and it is primarily designed for low temperature current steering (CS) D/A converters (DACs). A novel structure along with an analog calibration technique is proposed in designing the cell that helps it to overcome low temperature induced nonlinear and mismatch effects. Due to the flexible configuration of the cell architecture, it can be used in both LSB and MSB parts of a partially-segmented CS DAC. The current cell retains its 4-bit precision level from 300 K down to 4.2 K, and drives a load to 6.8 mV in 600 ps rise time. A 6-bit converter utilizing the cell achieves differential and integral nonlinearity of 0.17 LSB and 0.33 LSB, respectively, while its average power consumption is <3.2 mW from a 3 V power supply. It is fabricated using a commercial 0.5 single poly three metal silicon-on-sapphire CMOS process. Autors: Md Tanvir Rahman;Torsten Lehmann; Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs Publication date: Oct 2017, volume: 64, issue:10, pages: 1152 - 1156 Publisher: IEEE
» A Semianalytical Matching Approach for Power Amplifier With Extended Chebyshev Function and Real Frequency Technique
 Abstract:In this paper, an extended Chebyshev function is proposed to adapt the matching condition of the power amplifier (PA) by introducing a new factor. A set of impedance functions can be directly calculated along with the variation of a new variable, and the first element extracted from the functions is distributed in a wide range. In addition, the impedance function whose first element is the closest to the output capacitance of the transistor can be easily read out and selected as the original matching network. The fundamental impedance of the selected function will be reached a good matching state, and the impedances out of band will be on the edge of Smith chart. To achieve better performances, the real frequency technique is applied to adjust the harmonic impedances preventing it from falling into the low-efficiency region. Two PAs with a relative bandwidth of 34% and 75% are implemented to validate the proposed approach. Autors: Zhijiang Dai;Songbai He;Jun Peng;Chaoyi Huang;Weimin Shi;Jingzhou Pang; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Oct 2017, volume: 65, issue:10, pages: 3892 - 3902 Publisher: IEEE
» A Separation Principle for Underactuated Lossless Lagrangian Systems
 Abstract:We study under-actuated Lagrangian systems without dissipative forces, augmented by a chain of integrators. For such systems, we solve the open problem of global tracking control via position measurements only; strictly speaking, we establish uniform global asymptotic stability for the closed loop system. As a corollary, we obtain an original statement for flexible-joint robots, which closes a long-standing open problem of output feedback nonlinear control. Autors: Sofia Avila-Becerril;Antonio Loría;Elena Panteley; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5318 - 5323 Publisher: IEEE
» A Sequential Decomposition Framework and Method for Calibrating Dynamic Origin—Destination Demand in a Congested Network
 Abstract:This paper presents a two-stage model to calibrate the time-dependent, dynamic origin-destination (O–D) demand under congested traffic conditions. The first-stage model estimates O–D trip rates by minimizing link demand deviation with a one-norm formulation approach, so that over the calibration time period, the traffic demand on calibration links matches with the link demand from the field data. Due to its linear model structure, the first-stage model is more computationally effective and solvable on large real-life networks compared with the commonly seen least-square formulation. Then, a time-dependent user equilibrium traffic assignment model is formulated at the second stage to adjust the departure time profile iteratively, aiming to match the calibrated result with the field observed dynamic traffic condition, i.e., time-dependent speed profile. The second-stage model starts from the concept of a demand–capacity–volume relationship at a congested road segment, where demand exceeds supply, and utilizes shockwave theory to capture the differences between true demand and volume output, together with the idea of using travel time propagation between origin and bottleneck locations to infer real demand at the origin location. The two-stage model was implemented and tested in a case study in Tucson, AZ, USA, as an experimental proof of concept, which demonstrated the effectiveness of the proposed calibration framework and method under circumstances, in which the departure time profile was systematically distorted and initial demand solutions deviated from the true O–D matrices. Autors: Xianbiao Hu;Yi-Chang Chiu;Jorge A. Villalobos;Eric Nava; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Oct 2017, volume: 18, issue:10, pages: 2790 - 2797 Publisher: IEEE
» A Set Space Model for Feature Calculus
 Abstract:Processing natural language at the sentence level suffers from a sparse-feature problem caused by the limited number of words in a sentence. In this article, a Set Space Model (SSM) is proposed to utilize sentence information, the main idea being that, depending on structural characteristics or functional principles of linguistics, features in a sentence can be grouped into different sets. Feature calculus can then operate on the grouped features and capture structural information using external knowledge. The authors implement this method in a traditional information extraction task, with results showing significant and constant improvement in general information extraction. Autors: Yanping Chen;Qinghua Zheng;Ping Chen; Appeared in: IEEE Intelligent Systems Publication date: Oct 2017, volume: 32, issue:5, pages: 36 - 42 Publisher: IEEE
» A Shifting Framework for Set Queries
 Abstract:Set queries are fundamental operations in computer networks. This paper addresses the fundamental problem of designing a probabilistic data structure that can quickly process set queries using a small amount of memory. We propose a shifting bloom filter (ShBF) framework for representing and querying sets. We demonstrate the effectiveness of ShBF using three types of popular set queries: membership, association, and multiplicity queries. The key novelty of ShBF is on encoding the auxiliary information of a set element in a location offset. In contrast, prior BF-based set data structures allocate additional memory to store auxiliary information. We further extend our shifting framework from BF-based data structures to sketch-based data structures, which are widely used to store multiplicities of items. We conducted experiments using real-world network traces, and results show that ShBF significantly advances the state-of-the-art on all three types of set queries. Autors: Tong Yang;Alex X. Liu;Muhammad Shahzad;Dongsheng Yang;Qiaobin Fu;Gaogang Xie;Xiaoming Li; Appeared in: IEEE/ACM Transactions on Networking Publication date: Oct 2017, volume: 25, issue:5, pages: 3116 - 3131 Publisher: IEEE
» A SiC CMOS Digitally Controlled PWM Generator for High-Temperature Applications
 Abstract:This paper describes a silicon carbide pulse width modulation (PWM) signal generator in the 1.2 μm HiT-SiC CMOS process developed by Raytheon Systems Ltd. The design features a 6-b binary input, which allows for setting a system's duty cycle. The results presented in this paper utilize a field programmable gate array board in the test setup to dynamically set the duty cycle by controlling each bit. A control current is also available to give the user added flexibility for tuning the duty cycle. Experimental results show the duty cycle range of the PWM generator to be between 4.7% and 95.2% at 400°C. Sustained operation of the circuit is demonstrated over a period of 50 h at 300°C. Finally, the PWM generator is evaluated in the operation of a boost converter. Autors: Sajib Roy;Robert C. Murphree;Affan Abbasi;Ashfaqur Rahman;Shamim Ahmed;James Austin Gattis;A. Matt Francis;Jim Holmes;H. Alan Mantooth;Jia Di; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8364 - 8372 Publisher: IEEE
» A SiC Power MOSFET Loss Model Suitable for High-Frequency Applications
 Abstract:The reduced chip size and unipolar current conduction mechanism make silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) suitable for high-frequency power electronics applications. Modeling the switching process of the SiC power MOSFET with parasitic components is important for achieving higher efficiency and power density system design. Therefore, this paper proposes a new concise yet accurate switching loss model for SiC power MOSFETs. Addressing the limitations in experimental measurements, numerical simulations are conducted to validate the proposed model taking the output capacitance Coss discharge and charge into consideration. The role of the parasitic components in the second-order model is discussed in depth for switching losses. Furthermore, this paper also provides guidelines in designing the gate driver for ultrafast SiC power MOSFETs. Autors: Xuan Li;Junning Jiang;Alex Q. Huang;Suxuan Guo;Xiaochuan Deng;Bo Zhang;Xu She; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8268 - 8276 Publisher: IEEE
» A Simple Harmonic Reduction Method in Multipulse Rectifier Using Passive Devices
 Abstract:This paper proposes a novel and passive harmonic reduction method at dc link of multipulse rectifier (MPR). The proposed method uses a single-phase diode-bridge rectifier to generate circulating current, which can shape the input line current of MPR. The input side of the single-phase diode-bridge rectifier is connected with the secondary winding of interphase reactor (IPR), and its output side is connected with load, which can recycle the harmonic energy and feed to load. The operation mode of the single-phase diode-bridge rectifier is analyzed, and the turn ratio of the IPR is designed optimally. Under ideal condition, the proposed MPR operates as a 24-pulse rectifier, and its total harmonic distortion (THD) of input line current is about 7.6%. Most of all, the proposed method is easy to be used in different 12-pulse rectifier topologies, and its conduction losses are far less than that of the conventional double-tapped IPR. Simulation and experiment results show that the THD of input line current is less than 5%. Autors: Fangang Meng;Xiaona Xu;Lei Gao; Appeared in: IEEE Transactions on Industrial Informatics Publication date: Oct 2017, volume: 13, issue:5, pages: 2680 - 2692 Publisher: IEEE
» A Simplified Branch and Bound Approach for Model Predictive Control of Multilevel Cascaded H-Bridge STATCOM
 Abstract:Applying model predictive control (MPC) to cascaded H-bridge multilevel converters, while improving the dynamic performance, suffers from high computation burden due to substantial voltage vectors and switching combinations. In this paper, a simplified branch and bound approach is proposed to reduce the computation of the MPC for a cascaded H-bridge Static Synchronous Compensator (STATCOM). The underlying optimization problem of the current predictive control is a two-variable integer quadratic programming problem. With the proposed approach, the global optimal voltage vector can be selected within linear time instead of polynomial time. This is achieved by selecting the possible values of one variable as the branch, and enumerating the optimal integer results of each branch. The execution time of the proposed approach and conventional methods are compared to demonstrate the effectiveness of the proposed approach. Simulation and experimental results for a seven-level cascaded H-bridge STATCOM system are presented to verify the usability and reliability of the proposed approach. Autors: Yonglei Zhang;XiaoJie Wu;Xibo Yuan; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 7634 - 7644 Publisher: IEEE
» A Simplified Method for Retrieving Aerosol Optical Thickness Using Visibility Data Between 1980 and 2014, A Case Study in China
 Abstract:Analysis of long-term variations of aerosol optical thickness (AOT) is essential to understand the climate change and earth radiation budget. A simplified method was developed in this study to derive the AOT using more than thirty-year surface visibility and aerosol vertical distribution from LiDAR climatology of vertical aerosol structure for space-based LiDAR simulation studies data. Moderate resolution imaging spectroradiometer (MODIS) TERRA and AQUA daily measurements were used to evaluate the performance of the inferred AOT. Results show that the correlations of monthly AOT between MODIS measurements and inferred data are higher than 0.59 and the annual AOT values have stronger correlations (r > 0.82) than monthly data. The inferred AOT can capture the general spatial distribution similar to satellite images with long-term scale. The correlation of seasonal variation between two datasets is also higher than 0.77. The root mean squared error of inferred AOT relative to MODIS AOT is about 0.22 and 0.11 for monthly and yearly data, respectively. Analysis using singular value decomposition shows that the inferred AOT is consistent with MODIS measurements during 2002–2014 spatially and temporally. The average annual AOT in over 200 stations in China between 1980 and 2014 shows generally upward trends. Results from this paper can be used for further analysis of the aerosol effects on climate change in a regional scale. Autors: Zhao Yang Zhang;Man Sing Wong; Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Publication date: Oct 2017, volume: 10, issue:10, pages: 4409 - 4416 Publisher: IEEE
» A Sizing Methodology for Rise-Time Minimization of Dickson Charge Pumps With Capacitive Loads
 Abstract:A novel sizing methodology for Dickson charge pumps with pure capacitive loads is presented. The methodology is based on dynamic analysis to minimize the rise time of the charge pump up to 25% under a given circuit area. The methodology is validated through the implementation of a six-stage charge pump-based driver in 180-nm standard low-voltage CMOS technology. The driver is used for the excitation of ultrasonic transducers with 34 V at a resonance frequency of 220 KHz. A rise time of only 512 nS is achieved. The driver consumes 10.6 mA drawn from a 5-V supply at a pumping frequency of 50 MHz and occupies an area of 0.2 mm2. Autors: Ahmed Saeed;Sameh Ibrahim;Hani Fikry Ragai; Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs Publication date: Oct 2017, volume: 64, issue:10, pages: 1202 - 1206 Publisher: IEEE
» A Soft Robotic Tongue—Mechatronic Design and Surface Reconstruction
 Abstract:A novel soft robot mimicking the human tongue's motion is proposed for the purpose of measuring the tongue movement and interaction with its surrounding in vitro. In order to gain verisimilitude and flexibility, the robotic tongue is simplified from a biological tongue and is made of soft materials, including silicone rubber forming the extensible layer and polydimethylsiloxane composing the less extensible layer. The robotic tongue can deform when pressurized in a series of embedded chambers due to the difference in strain of the two layers. General deformation results are obtained through finite-element method simulations and initial parameters of the structural design are improved. The robotic tongue is fabricated with 3-D printed molds by curing the silicone rubber at room temperature. The pneumatic actuation system is mainly composed of solenoid directional valves and pressure sensors. Five types of basic deformation are achieved including roll-up, roll-down, elongation, groove, and twist. Furthermore, a surface reconstruction method based on multisurface merging is proposed to describe the deformed surface of the robotic tongue quantitatively, which will be used in the surface-based motion control in the future. Motion tracking is carried out to verify the reconstruction results. The results of verification indicate that the proposed method is qualified to reconstruct the surface of the robotic tongue. Autors: Xuanming Lu;Weiliang Xu;Xiaoning Li; Appeared in: IEEE/ASME Transactions on Mechatronics Publication date: Oct 2017, volume: 22, issue:5, pages: 2102 - 2110 Publisher: IEEE
» A Solution to Press-Pack Packaging of SiC MOSFETS
 Abstract:This paper proposes a packaging method for SiC MOSFETs that provides a feasible solution of implementing press-pack packaging on SiC MOSFETs to extend the application of SiC devices into the high power range. The challenges in realizing press-pack packaging of SiC MOSFETs are addressed, and the solutions are proposed that fit the specific requirements of SiC MOSFET. To achieve pressure contact on SiC MOSFETs, miniature and flexible press pins called “fuzz buttons” are used in a low-profile interposer to realize die top side connection. Since the press-pack does not provide internal insulation between the active device and the heatsink, the heatsink is included in the power loop. To avoid large parasitic loop inductance being introduced by the heatsinks, a microchannel heatsink is developed which has a low thickness while remaining adequate heat dissipation efficiency. The structure and assembly process flow of the press-pack SiC MOSFET are provided. A half-bridge stack prototype with two press-packs and three heatsinks is developed. The thermal and electrical performances of the press-pack and the half-bridge stack are evaluated by simulations and tests to validate the feasibility of the proposed packaging approach. Autors: Nan Zhu;H. Alan Mantooth;Dehong Xu;Min Chen;Michael D. Glover; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8224 - 8234 Publisher: IEEE
» A Sparse Bayesian Learning Approach for Through-Wall Radar Imaging of Stationary Targets
 Abstract:Through-the-wall radar (TWR) imaging is an emerging technology that enables detection and localization of targets behind walls. In practical operations, TWR sensing faces several technical difficulties including strong wall clutter and missing data measurements. This paper proposes a sparse Bayesian learning (SBL) approach for wall-clutter mitigation and scene reconstruction from compressed data measurements. In the proposed approach, SBL is used to model both the intraantenna signal sparsity and interantenna signal correlation for estimating the antenna signals jointly. Here, the Bayesian framework provides a learning paradigm for sharing measurements among spatial positions, leading to accurate and stable antenna signal estimation. Furthermore, the task of wall-clutter mitigation is formulated as a probabilistic inference problem, where the wall-clutter subspace and its dimension are learned automatically using the mechanism of automatic relevant determination. Automatic discrimination between targets and clutter allows an effective target image formation, which is performed using Bayesian approximation. Experimental results with both real and simulated TWR data demonstrate the effectiveness of the SBL approach in indoor target detection and localization. Autors: Van Ha Tang;Son Lam Phung;Fok Hing Chi Tivive;Abdesselam Bouzerdoum; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2485 - 2501 Publisher: IEEE
» A Sparse Learning Framework for Joint Effect Analysis of Copy Number Variants
 Abstract:Copy number variants (CNVs), including large deletions and duplications, represent an unbalanced change of DNA segments. Abundant in human genomes, CNVs contribute to a large proportion of human genetic diversity, with impact on many human phenotypes. Although recent advances in genetic studies have shed light on the impact of individual CNVs on different traits, the analysis of joint effect of multiple interactive CNVs lags behind from many perspectives. A primary reason is that the large number of CNV combinations and interactions in the human genome make it computationally challenging to perform such joint analysis. To address this challenge, we developed a novel sparse learning framework that combines sparse learning with biological networks to identify interacting CNVs with joint effect on particular traits. We showed that our approach performs well in identifying CNVs with joint phenotypic effect using simulated data. Applied to a real human genomic dataset from the 1,000 Genomes Project, our approach identified multiple CNVs that collectively contribute to population differentiation. We found a set of multiple CNVs that have joint effect in different populations, and affect gene expression differently in distinct populations. These results provided a collection of CNVs that likely have downstream biomedical implications in individuals from diverse population backgrounds. Autors: Zhiyong Wang;Benika Hall;Jinbo Xu;Xinghua Shi; Appeared in: IEEE/ACM Transactions on Computational Biology and Bioinformatics Publication date: Oct 2017, volume: 14, issue:5, pages: 1013 - 1027 Publisher: IEEE
» A Stand-Alone Approach for High-Sensitivity GNSS Receivers in Signal-Challenged Environment
» A State of Charge Estimation Method Based on $H_\infty$ Observer for Switched Systems of Lithium-Ion Nickel–Manganese–Cobalt Batteries
 Abstract:Accurately estimating the state of charge (SOC) of the battery is the basis of battery management system. Based on a linear equivalent circuit model, this paper has introduced a switched battery model to model the complicated physical and chemical reactions properties. The SOC is determined by the battery electromotive force at a present battery state that is estimated through the H∞ switched observer for dealing with the inexact or unknown statistical properties of the modeling and measurement errors. The observer design criterion is presented to ensure the H∞ performance of the switched observer. Then, the proposed method is applied successfully to estimate the SOC by utilizing the current and terminal voltage. Finally, the experimental results have demonstrated that the proposed method can provide high accuracy and robustness for SOC estimation. Autors: Cong-zhi Liu;Qiao Zhu;Liang Li;Wei-qun Liu;Ling-Yan Wang;Neng Xiong;Xiang-yu Wang; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8128 - 8137 Publisher: IEEE
» A Statistical Exploration of Protocol Adoption
 Abstract:The development and adoption of new protocols (or of extensions to existing protocols) is arguably central to the Internet’s evolution. However, and in spite of over 40 years of experience with this process, we have limited understanding of what factors may contribute to a protocol’s success. A sound technical design and a well-grounded purpose are obviously important, but we have many examples of failures that met those two criteria. What other factors affect a protocol’s likelihood of success, and under what circumstances? We investigate this question through a statistical approach, based on analyzing a set of about 250 Internet standard documents, Internet engineering task force request for comments (RFCs). We characterize these RFCs using a number of key features, which we then seek to associate with positive or negative odds when it comes to success. Our high-level results are intuitive, e.g., protocols that call for Internet-wide adoption face greater challenges. Focusing on more targeted subsets of protocols reveals more subtle and possibly more interesting differences between areas of the Internet landscape. We also apply our prediction framework to IPv6, and use different “what-if” scenarios to explore what might have affected its deployment. Autors: Mehdi Nikkhah;Aman Mangal;Constantine Dovrolis;Roch Guérin; Appeared in: IEEE/ACM Transactions on Networking Publication date: Oct 2017, volume: 25, issue:5, pages: 2858 - 2871 Publisher: IEEE
» A Study on Piezoelectric Energy-Harvesting Wireless Sensor Networks Deployed in a Weak Vibration Environment
 Abstract:Wireless sensor network (WSN) is an interestingly promising technology with many applications in intelligent environment-monitoring. Its energy consumption is, however, essentially challenged after it is deployed. In this paper, we developed a low-resonant-frequency piezoelectric energy harvesting device as an alternative to power WSN deployed in a weak vibration environment. An energy management module, equipped with a full-bridge rectifier (FBR), a fully self-powered voltage controller, and a logic-level protection circuit was designed to enable a regulated voltage to intermittently drive WSN for temperature monitoring. The power transfer efficiency of FBR reached 42%, presenting a good performance/cost ratio in the case of a relatively high open-circuit voltage of 8 V and a low rectified voltage of 3.3 V. The experimental results have demonstrated that the proposed WSN was successfully driven at an interval time of less than 1 min, and fully self-powered by the scavenged energy from the environmental vibration source of a 0.15-g acceleration and a 40-Hz vibration frequency. Autors: Yanhui Han;Yue Feng;Zejie Yu;Wenzhong Lou;Huicong Liu; Appeared in: IEEE Sensors Journal Publication date: Oct 2017, volume: 17, issue:20, pages: 6770 - 6777 Publisher: IEEE
» A Subspace Approach to Spectral Quantification for MR Spectroscopic Imaging
 Abstract:Objective: To provide a new approach to spectral quantification for magnetic resonance spectroscopic imaging (MRSI), incorporating both spatial and spectral priors. Methods: A novel signal model is proposed, which represents the spectral distributions of each molecule as a subspace and the entire spectrum as a union of subspaces. Based on this model, the spectral quantification can be solved in two steps: 1) subspace estimation based on the empirical distributions of the spectral parameters estimated using spectral priors; and 2) parameter estimation for the union-of-subspaces model incorporating spatial priors. Results: The proposed method has been evaluated using both simulated and experimental data, producing impressive results. Conclusion: The proposed union-of-subspaces representation of spatiospectral functions provides an effective computational framework for solving the MRSI spectral quantification problem with spatiospectral constraints. Significance: The proposed approach transforms how the MRSI spectral quantification problem is solved and enables efficient and effective use of spatiospectral priors to improve parameter estimation. The resulting algorithm is expected to be useful for a wide range of quantitative metabolic imaging studies using MRSI. Autors: Yudu Li;Fan Lam;Bryan Clifford;Zhi-Pei Liang; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Oct 2017, volume: 64, issue:10, pages: 2486 - 2489 Publisher: IEEE
» A Sugiyama-Like Decoding Algorithm for Convolutional Codes
 Abstract:We propose a decoding algorithm for a class of convolutional codes called skew Reed-Solomon convolutional codes. These are convolutional codes of designed Hamming distance endowed with a cyclic structure yielding a left ideal of a non-commutative ring (a quotient of a skew polynomial ring). In this setting, right and left division algorithms exist, so our algorithm follows the guidelines of the Sugiyama’s procedure for finding the error locator and error evaluator polynomials for Goppa block codes. Autors: José Gómez-Torrecillas;F. J. Lobillo;Gabriel Navarro; Appeared in: IEEE Transactions on Information Theory Publication date: Oct 2017, volume: 63, issue:10, pages: 6216 - 6226 Publisher: IEEE
» A Survey of GNSS-Based Research and Developments for the European Railway Signaling
 Abstract:Railways have already introduced satellite-based localization systems for non-safety related applications. Driven by economic reasons, the use of these systems for new services and, in particular, their introduction in signaling system is seriously investigated today and tested all around the world. Because of the weight of their history, their strong normative context, and the high requested level of safety, the introduction is relatively slow. The aim of this paper is to provide a survey of past and current programs dealing with global navigation satellite systems as a basis to introduce main issues relative to context, standards, performance requirements, and safety proofs. Links with aeronautical concepts are also presented, illustrating the transposable principles and the limits due to the land transport environment. Autors: Juliette Marais;Julie Beugin;Marion Berbineau; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Oct 2017, volume: 18, issue:10, pages: 2602 - 2618 Publisher: IEEE
» A Survey of Train Positioning Solutions
 Abstract:Positioning accurately and safely a train is nowadays a great challenge. That includes currently available railway sensors and new candidate sensors for data fusion. Global Navigation Satellite System and Inertial Measurement Unit sensors arise as prominent technologies to incorporate in railways. Although satellite-based train localization tests can be found in the scientific literature, there are no common criteria to evaluate the performance of the positioning achieved. In this paper, a series of criteria is defined and justified in order to be able to evaluate the most recent and relevant works related to train positioning. The results of this comparative analysis are gathered in tables, where the criteria defined are applied to the works compiled. According to the results obtained, a research gap in safety related applications is found. It is concluded that the economic viability of given solutions should be explored, so as to design an on-board train-integrated positioning system. Autors: Jon Otegui;Alfonso Bahillo;Iban Lopetegi;Luis Enrique Díez; Appeared in: IEEE Sensors Journal Publication date: Oct 2017, volume: 17, issue:20, pages: 6788 - 6797 Publisher: IEEE
» A Survey on Behavior Recognition Using WiFi Channel State Information
 Abstract:In this article, we present a survey of recent advances in passive human behavior recognition in indoor areas using the channel state information (CSI) of commercial WiFi systems. The movement of the human body parts cause changes in the wireless signal reflections, which result in variations in the CSI. By analyzing the data streams of CSIs for different activities and comparing them against stored models, human behavior can be recognized. This is done by extracting features from CSI data streams and using machine learning techniques to build models and classifiers. The techniques from the literature that are presented herein have great performance; however, instead of the machine learning techniques employed in these works, we propose to use deep learning techniques such as long-short term memory (LSTM) recurrent neural networking (RNN) and show the improved performance. We also discuss different challenges such as environment change, frame rate selection, and the multi-user scenario; and finally suggest possible directions for future work. Autors: Siamak Yousefi;Hirokazu Narui;Sankalp Dayal;Stefano Ermon;Shahrokh Valaee; Appeared in: IEEE Communications Magazine Publication date: Oct 2017, volume: 55, issue:10, pages: 98 - 104 Publisher: IEEE
» A Survey on Non-Orthogonal Multiple Access for 5G Networks: Research Challenges and Future Trends
 Abstract:Non-orthogonal multiple access (NOMA) is an essential enabling technology for the fifth-generation (5G) wireless networks to meet the heterogeneous demands on low latency, high reliability, massive connectivity, improved fairness, and high throughput. The key idea behind NOMA is to serve multiple users in the same resource block, such as a time slot, subcarrier, or spreading code. The NOMA principle is a general framework, and several recently proposed 5G multiple access schemes can be viewed as special cases. This survey provides an overview of the latest NOMA research and innovations as well as their applications. Thereby, the papers published in this special issue are put into the context of the existing literature. Future research challenges regarding NOMA in 5G and beyond are also discussed. Autors: Zhiguo Ding;Xianfu Lei;George K. Karagiannidis;Robert Schober;Jinhong Yuan;Vijay K. Bhargava; Appeared in: IEEE Journal on Selected Areas in Communications Publication date: Oct 2017, volume: 35, issue:10, pages: 2181 - 2195 Publisher: IEEE
» A Switched Reluctance Motor Drive Using Photovoltaic Transistors: Principle, Prototype, Experimental, and Numerical Results
 Abstract:A solar-powered switch reluctance motor drive using photovoltaic transistors (PVTs) is presented. The expression “PVT” is used to designate a conventional photovoltaic (PV) cell used as a light-controlled power transistor. To obtain a motor drive, a set of PVTs controls the current fed from an external dc power source to the motor phases. The control is achieved by modulating the sunlight hitting the PVTs using a shutter driven by the motor rotor. If the external dc source is a solar panel, the resulting system is able to convert light energy into mechanical energy, without the need of any brushes or other power electronics components. This system could be more affordable and reliable than conventional ones, and therefore, is well suited for off-grid applications like water pumping. This paper first discusses the operation of a PVT through the proposition and the validation of a model. Then, the operating principle of a PVT inverter is clarified. Finally, experimental and numerical results on the first PVT inverter-fed switched reluctance motor are reported. A prototype was built using a switched reluctance motor 6/4 and 12 PVTs. It was here connected to an external 12 V dc power source as a step before using a solar PV source. Results that the PVT inverter-fed switched reluctance motor was operating as expected and provided useful power. Autors: Loïc Quéval;Alain Coty;Lionel Vido;Raimund Gottkehaskamp;Bernard Multon; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4886 - 4893 Publisher: IEEE
» A System for Simultaneous Finger Joints Goniometric Measurements Based on Inertial Sensors
 Abstract:In this work, a system to record continuously and simultaneously the flexion and extension of finger joints and to compute a range of motion of the hand joints is presented. The system is based on micro-inertial sensors and a graphical interface in LabVIEW with a mathematical algorithm for signal conditioning. Ten sensors were attached to fingers with adjustable velcro belts, eight on proximal and distal phalanges from index to little fingers, one on the proximal phalanx of the thumb and another on the hand dorsum. The evaluation protocol consisted of 3 sessions of 10 repetitions each, on both hands of 6 healthy volunteers where the angular trajectory was recorded during grasping a 7.8 cm diameter sphere. A statistical analysis was performed in order to determine the variation among the measurements. The purpose of this study was to demonstrate the suitability of this system for simultaneous measurements of range of motion during flexion and extension, considering that it can be used interchangeably in the two hands, regardless the size. The results showed that the developed system is suitable for registering objectively the range of motion of the hand. Autors: Sandra Arias;Pablo Rogeli;Laura Garay;Blanca Tovar;Josefina Gutierrez;Eladio Cardiel; Appeared in: IEEE Latin America Transactions Publication date: Oct 2017, volume: 15, issue:10, pages: 1821 - 1826 Publisher: IEEE
» A Tale of Ten Cities: Characterizing Signatures of Mobile Traffic in Urban Areas
 Abstract:Urban landscapes present a variety of socio-topological environments that are associated to diverse human activities. As the latter affect the way individuals connect with each other, a bound exists between the urban tissue and the mobile communication demand. In this paper, we investigate the heterogeneous patterns emerging in the mobile communication activity recorded within metropolitan regions. To that end, we introduce an original technique to identify classes of mobile traffic signatures that are distinctive of different urban fabrics. Our proposed technique outperforms previous approaches when confronted to ground-truth information, and allows characterizing the mobile demand in greater detail than that attained in the literature to date. We apply our technique to extensive real-world data collected by major mobile operators in 10 cities. Results unveil the diversity of baseline communication activities across countries, but also provide evidence of the existence of a number of mobile traffic signatures that are common to all studied areas and specific to particular land uses. Autors: Angelo Furno;Marco Fiore;Razvan Stanica;Cezary Ziemlicki;Zbigniew Smoreda; Appeared in: IEEE Transactions on Mobile Computing Publication date: Oct 2017, volume: 16, issue:10, pages: 2682 - 2696 Publisher: IEEE
» A Technique for Efficient Query Estimation over Distributed Data Streams
 Abstract:Distributed data stream mining in a sliding window has emerged recently, due to its applications in many domains including large Telecoms and Internet Service Providers, financial tickers, ATM and credit card operations in banks and transactions in retail chains. Many of these large-scale applications prohibit monitoring data centrally at a single location due to their massive volume of the data; therefore, data acquisition, processing, and mining tasks are often distributed to a number of processing nodes, which monitor their local streams and exchange only the summary of data either periodically or on demand. While this offer many advantages, distributed stream applications possess significant challenges including problems related to an online analysis of the recent data, communication efficiency and various estimation of various complex queries. There are few existing techniques which solve problems related to distributed sliding window data stream; however, those techniques are focused on solving only simple problems and require high space, query, and communication cost, which can be a bottleneck for many of these large scale applications. In this paper, we propose an efficient query estimation technique by constructing a small sketch of the data stream. The constructed sketch uses a deterministic sliding window model and can estimate various complex queries, for both centralized and distributed applications; including point queries (i.e., range queries and heavy hitter queries), quantiles, inner product, and self-join size queries, with deterministic guarantees on the precision. The proposed approach improves upon recent existing work for these problems, in terms of the memory and query cost in a centralized setting and in terms of communication cost and merge complexity in a distributed setting. It requires memory (where is a user defined parameter), can provide estimates in time, and processes each incoming record in amortized time. Detailed experimental analysis, both in centralized and distributed settings demonstrates that in practice the proposed approach uses about six times less memory, and has about eight times less query time when compared to ECM sketches. In a distributed application, the proposed technique also significantly improves (around seven times) on the communication cost between distributed sites. Autors: Zubair Shah;Abdun Naser Mahmood;Zahir Tari;Albert Y. Zomaya; Appeared in: IEEE Transactions on Parallel and Distributed Systems Publication date: Oct 2017, volume: 28, issue:10, pages: 2770 - 2783 Publisher: IEEE
» A Thermal Ink-Jet Printer Head Prototype With Full Carbon Based Microbubble Generator
 Abstract:This paper presents the development of a novel thermal ink-jet printer head prototype using full carbon-based microbubble generators with carbon nanotubes as heating elements and graphene as electrodes. Meanwhile, each microbubble generator is equipped with a carbon nanotube sensor to real-timely probe the temperature of its surrounding micro-environment. With an array of microbubble generators and sensors fabricated on quartz glass, as well as a microfluidic structure constructed by the micromachined silicon, the printer head prototype is formed by an anodic silicon-glass bonding process with several scattered graphene film flakes as medium. Droplet ejection with volume as tiny as ~0.03 pl corresponding to a very high spatial resolution of >2000 dpi driven by two microbubble valves is demonstrated by the printing unit in the prototype. Increasing the input power cannot only speed up the bubble nucleation and growth, but also improve the utilizing efficiency of electric heating energy. The experimental detected temperature variation in the printing unit reveals its nonlinear heat convection property by comparison with the theoretical calculation by finite-element analysis. [2017-0048] Autors: Yunhong Xiang;Lvhui Jiang;Yu Zhu;Changsheng Chen;Yangyang Chen;Wenli Zhou; Appeared in: Journal of Microelectromechanical Systems Publication date: Oct 2017, volume: 26, issue:5, pages: 1040 - 1046 Publisher: IEEE
» A Three-State Received Signal Strength Model for Device-Free Localization
 Abstract:The indoor radio propagation channel is typically modeled as a two-state time-variant process, where one of the states represents the channel when the environment is static, whereas the other state characterizes the medium when it is altered by people. In this paper, the aforementioned process is augmented with an additional state. It is shown that the changes in received signal strength are dictated by: 1) electronic noise, when a person is not present in the monitored area; 2) reflection, when a person is moving in the close vicinity of line-of-sight; and 3) shadowing, when a person is obstructing the line-of-sight component of the transmitter–receiver pair. Statistical and spatial models for the three states are derived, and the models are empirically validated. Based on the models, a link line monitoring system is designed, which aims to, first, estimate the temporal state of the channel using a hidden Markov model, and, second, track a person using a particle filter. The results suggest that the presented system outperforms other state-of-the-art systems in terms of localization accuracy while increasing size of the link's sensing region. Autors: Ossi Kaltiokallio;Hüseyin Yiğitler;Riku Jäntti; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Oct 2017, volume: 66, issue:10, pages: 9226 - 9240 Publisher: IEEE
» A Tight Upper Bound on the Second-Order Coding Rate of the Parallel Gaussian Channel With Feedback
 Abstract:This paper investigates the asymptotic expansion for the maximum rate of fixed-length codes over a parallel Gaussian channel with feedback under the following setting: a peak power constraint is imposed on every transmitted codeword, and the average error probabilities of decoding the transmitted message are non-vanishing as the blocklength increases. The main contribution of this paper is a self-contained proof of an upper bound on the first- and second-order asymptotics of the parallel Gaussian channel with feedback. The proof techniques involve developing an information spectrum bound followed by using Curtiss’ theorem to show that a sum of dependent random variables associated with the information spectrum bound converges in distribution to a sum of independent random variables, thus facilitating the use of the usual central limit theorem. Combined with existing achievability results, our result implies that the presence of feedback does not improve the first- and second-order asymptotics. Autors: Silas L. Fong;Vincent Y. F. Tan; Appeared in: IEEE Transactions on Information Theory Publication date: Oct 2017, volume: 63, issue:10, pages: 6474 - 6486 Publisher: IEEE
» A TLM-Based Wideband Adjoint Variable Method for Sensitivity Analysis of Non-Dispersive Anisotropic Structures
 Abstract:We propose a wideband theory for adjoint variable sensitivity analysis of problems with non-dispersive anisotropic materials. The method is developed based on the transmission line modeling (TLM) technique. The anisotropic material property can be the full tensors of permittivity, permeability, electrical conductivity, magnetic resistivity, magnetoelectric coupling, or electromagnetic coupling. The tensors are assumed constant and may contain non-diagonal elements. Our algorithm estimates the gradient of the desired response with respect to all the designable parameters using at most one extra simulation, regardless of the number of parameters. The theory has been implemented in an algorithm for 2-D and 3-D structures. Our estimated sensitivities match well the computationally expensive central finite difference approximations. Autors: Laleh Seyyed Kalantari;Osman S. Ahmed;Mohamed H. Bakr;Natalia K. Nikolova; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5267 - 5278 Publisher: IEEE
» A tool to prioritize code smells in distributed development
 Abstract:A code smell is a symptom in the source code that helps to identify a design problem. Several tools for detecting and ranking code smells according to their criticality to the system have been developed. However, existing works assume a centralized development approach, which does not consider systems being developed in a distributed fashion. The main problem in a distributed group of developers is that a tool cannot always ensure a global vision of (smells of) the system, and thus inconsistencies among the rankings provided by each developer are likely to happen. These inconsistencies often cause unnecessary refactorings and might not focus the whole team on the critical smells system-wide. Along this line, this work proposes a multi-agent tool, called D-JSpIRIT, which helps individual developers to reach a consensus on their smell rankings by means of distributed optimization techniques. Autors: Hernan Vazquez;Claudia Marcos;Santiago Vidal;Jorge Andres Diaz Pace; Appeared in: IEEE Latin America Transactions Publication date: Oct 2017, volume: 15, issue:10, pages: 1941 - 1947 Publisher: IEEE
» A Trust Label System for Communicating Trust in Cloud Services
 Abstract:Cloud computing is rapidly changing the digital service landscape. A proliferation of Cloud providers has emerged, increasing the difficulty of consumer decisions. Trust issues have been identified as a factor holding back Cloud adoption. The risks and challenges inherent in the adoption of Cloud services are well recognised in the computing literature. In conjunction with these risks, the relative novelty of the online environment as a context for the provision of business services can increase consumer perceptions of uncertainty. This uncertainty is worsened in a Cloud context due to the lack of transparency, from the consumer perspective, into the service types, operational conditions and the quality of service offered by the diverse providers. Previous approaches failed to provide an appropriate medium for communicating trust and trustworthiness in Clouds. A new strategy is required to improve consumer confidence and trust in Cloud providers. This paper presents the operationalisation of a trust label system designed to communicate trust and trustworthiness in Cloud services. We describe the technical details and implementation of the trust label components. Based on a use case scenario, an initial evaluation was carried out to test its operations and its usefulness for increasing consumer trust in Cloud services. Autors: Vincent C. Emeakaroha;Kaniz Fatema;Lisa van der Werff;Philip Healy;Theo Lynn;John P. Morrison; Appeared in: IEEE Transactions on Services Computing Publication date: Oct 2017, volume: 10, issue:5, pages: 689 - 700 Publisher: IEEE
» A Two-Level Game Theory Approach for Joint Relay Selection and Resource Allocation in Network Coding Assisted D2D Communications
 Abstract:Device-to-device (D2D) communication, which enables direct transmissions between mobile devices to improve spectrum efficiency, is one of the preferable candidate technologies for the next generation cellular network. Network coding, on the other hand, is widely used to improve throughput in ad hoc networks. Thus, the performance of D2D communications in cellular networks can potentially benefit from network coding. Aiming to improve the achievable capacity of D2D communications, we propose a system with inter-session network coding enabled to assist D2D transmissions. We formulate the joint problem of relay selection and resource allocation in network coding assisted D2D communications, and obtain the overall capacity of the network under complex interference conditions as a function of the relay selection and resource allocation. To solve the formulated problem, we propose a two-level decentralized approach termed NC-D2D, which solves the relay selection and resource allocation problems alternatively to obtain stable solutions for these two problems. Specifically, a coalition formation game associates relays with D2D pairs to enable network coding aided transmissions, and a greedy algorithm based game allocates limited cellular resources to D2D pairs and relays in NC-D2D, respectively. The performances of the proposed scheme is evaluated through extensive simulations to prove its superiority. Autors: Chuhan Gao;Yong Li;Yulei Zhao;Sheng Chen; Appeared in: IEEE Transactions on Mobile Computing Publication date: Oct 2017, volume: 16, issue:10, pages: 2697 - 2711 Publisher: IEEE
» A Two-Line Time-Domain Gating Method for Characterization of Test Fixture With via Hole Discontinuity
 Abstract:The time-domain gating method (TGM) is an accurate and useful method to characterize the test fixtures used in the measurement of high-speed connectors. However, its accuracy can be degraded by the gating error when the test fixture contains the impedance discontinuity near the fixture end facing the device under test. To overcome this limitation, this letter proposes a two-line TGM (2LTGM) for characterizing the test fixtures having the discontinuities such as via holes. The proposed method does not require any modification of the test fixtures with the help of the proposed test structures and T-parameter extraction procedure. The experimental results show that the proposed 2LTGM has an 8 dB lower mean square error than the conventional TGM for the test fixtures having via hole discontinuities at the end. We expect that the 2LTGM can improve the accuracy for characterizing the test fixtures with any discontinuities not limited to the via holes. Autors: Jaeyong Cho;Byung-Sung Kim;Jonghyuck Jeong;Junseong Kim;Kibeom Kim;Karam Hwang;Hwiseob Lee;Seungil Jeung;Seungyoung Ahn; Appeared in: IEEE Microwave and Wireless Components Letters Publication date: Oct 2017, volume: 27, issue:10, pages: 936 - 938 Publisher: IEEE
» A Two-Phase 3-D Reconstruction Approach for Light Microscopy Axial-View Imaging
 Abstract:Three-dimensional representations in light microscopy are important for accurate shape assessment of model systems in biosciences. The computational multiview 3-D reconstruction seems feasible in obtaining the 3-D representations in particular for high-throughput. The specimen for imaging can have properties, i.e., transparency and translucency, that impede the detection of well-defined boundaries. Consequently, 3-D reconstruction and measurements, i.e., volume and surface area will be inaccurate. The motivation in this paper is therefore to develop a two-phase 3-D reconstruction approach for light microscopy axis-view imaging that can deal with these properties. In phase I of this approach, we develop an improved 3-D volumetric representation defined as the confidence map. This is derived from texture-augmented axial-view images of the specimen. In phase II, the 3-D reconstruction is accomplished by searching the optimal surface for the specimen over the confidence map. Subsequently, from the obtained 3-D reconstruction, 3-D measurements can be extracted. We present a high-throughput axial-view imaging architecture in light microscopy based on the vertebrate automated screening technology device. Using this imaging architecture, we present three typical datasets using different imaging modalities, which includes zebrafish larvae in bright-field and zebrafish liver in fluorescence. In the experiments, we have applied our approach on these datasets. We find that our approach yields precise 3-D shape representation and natural visualization. In comparison with a groundtruth setup, we have obtained accurate 3-D measurements both for the organism and the organ, which holds a promising shape assessment for model systems in biosciences. Autors: Yuanhao Guo;Yunpeng Zhang;Fons J. Verbeek; Appeared in: IEEE Journal of Selected Topics in Signal Processing Publication date: Oct 2017, volume: 11, issue:7, pages: 1034 - 1046 Publisher: IEEE
» A Unification of Intuitionistic Fuzzy Calculus Theories Based on Subtraction Derivatives and Division Derivatives
 Abstract:Intuitionistic fuzzy calculus replaces real numbers in classical calculus with intuitionistic fuzzy numbers that are the basic elements of Atanassov's intuitionistic fuzzy sets. Intuitionistic fuzzy calculus consists of two parallel parts, which are respectively developed based on the subtraction derivatives and the division derivatives. This paper focuses on building the relationships between the two independent intuitionistic fuzzy calculus theories, and unifying them into a whole theory. Autors: Qian Lei;Zeshui Xu; Appeared in: IEEE Transactions on Fuzzy Systems Publication date: Oct 2017, volume: 25, issue:5, pages: 1023 - 1040 Publisher: IEEE
» A Unified Framework for Deterministic and Probabilistic $\mathscr {D}$-Stability Analysis of Uncertain Polynomial Matrices
 Abstract:In control theory, we are often interested in robust -stability analysis, which aims at verifying if all the eigenvalues of an uncertain matrix lie in a given region . Although many algorithms have been developed to provide conditions for an uncertain matrix to be robustly -stable, the problem of computing the probability of an uncertain matrix to be -stable is still unexplored. The goal of this paper is to fill this gap in two directions. First, the only constraint on the stability region that we impose is that its complement is a semialgebraic set. This comprises many important cases in robust control theory. Second, the -stability analysis problem is formulated in a probabilistic framework, by assuming that only few probabilistic information is available on the uncertain parameters, such as support and some moments. We will show how to compute the minimum probability that the matrix is -stable by using convex relaxations based on the theory of moments. Autors: Dario Piga;Alessio Benavoli; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5437 - 5444 Publisher: IEEE
» A Unified Robust Motion Controller Design for Series Elastic Actuators
 Abstract:Series elastic actuators (SEAs) have several mechanical superiorities over conventional stiff and non-back-drivable actuators, e.g., lower reflected inertia at output, greater shock tolerance, low-cost force measurement, energy storage, safety, and so on. However, their applications generally suffer from performance limitations, particularly in position control, due to insufficient controller designs. This paper proposes a unified active disturbance rejection motion controller for the robust position and force control problems of SEAs by using differential flatness and disturbance observer. It can suppress not only matched but also mismatched disturbances. Robust state and control input references are systematically generated in terms of a fictitious design variable, namely differentially flat output, estimations of disturbances and their successive time derivatives. The proposed robust motion controller improves the performance of SEAs when they suffer from internal and external disturbances, such as friction, inertia variation and external load, in real implementations. Experimental results are given to validate the proposal. Autors: Emre Sariyildiz;Gong Chen;Haoyong Yu; Appeared in: IEEE/ASME Transactions on Mechatronics Publication date: Oct 2017, volume: 22, issue:5, pages: 2229 - 2240 Publisher: IEEE
» A Unified Solution to Cognitive Radio Programming, Test and Evaluation for Tactical Communications
» A Versatile and Accurate Compact Model of Memristor With Equivalent Resistor Topology
 Abstract:Memristor appeals to a wide research field as the fourth passive element, and its model has been a necessary topic for future circuit applications. In this letter, a novel compact model of memristor, based on the equivalent resistor topology of variable conductive filaments, is presented. Since the formation and annihilation of conductive filaments is a natural mechanism of mainstream memristor, the model is essential and so more accurate than those nonlinear dopant drift models. On the other hand, the equivalent resistor idea makes our model versatile and efficient comparing with some complex physical process methods, and fulfills the requirements of circuit design. The versatility and accuracy of our compact model have been verified by the results that it can reduce at least 30% error in a Pt/TiO2/TiO2+x/Pt type memristor and at least 20% error in a Ta/TaOx/Pt type memristor, comparing with some popular models. Moreover it is easier to be implemented in Verilog-A, which possesses more flexibility and higher applicability in circuit design. Autors: Ruohua Zhu;Sheng Chang;Hao Wang;Qijun Huang;Jin He;Fan Yi; Appeared in: IEEE Electron Device Letters Publication date: Oct 2017, volume: 38, issue:10, pages: 1367 - 1370 Publisher: IEEE
» A Versatile Noise Performance Metric for Electrical Impedance Tomography Algorithms
 Abstract:Electrical impedance tomography (EIT) is an emerging technology for real-time monitoring of patients under mechanical ventilation. EIT has the potential to offer continuous medical monitoring while being noninvasive, radiation free, and low cost. Due to their ill-posedness, image reconstruction typically uses regularization, which implies a hyperparameter controlling the tradeoff between noise rejection and resolution or other accuracies. In order to compare reconstruction algorithms, it is common to choose hyperparameter values such that the reconstructed images have equal noise performance (NP), i.e., the amount of measurement noise reflected in the images. For EIT many methods have been suggested, but none work well when the data originate from different measurement setups, such as for different electrode positions or measurement patterns. To address this issue, we propose a new NP metric based on the average signal-to-noise ratio in the image domain. The approach is validated for EIT using simulation experiments on a human thorax model and measurements on a resistor phantom. Results show that the approach is robust to the measurement configuration (i.e., number and position of electrodes, skip pattern) and the reconstruction algorithm used. We propose this novel approach as a way to select optimized measurement configurations and algorithms. Autors: Fabian Braun;Martin Proença;Josep Solà;Jean-Philippe Thiran;Andy Adler; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Oct 2017, volume: 64, issue:10, pages: 2321 - 2330 Publisher: IEEE
» A Wafer Prealignment Algorithm Based on Fourier Transform and Least Square Regression
 Abstract:Automatic wafer prealignment is an important process in wafer manufacturing, whereby its flat edge is set at a predefined angle and its center is set in a predefined position; translational and rotational movement compensate for deviation of the wafer. However, as the traditional wafer prealignment algorithm depends on marked templates at the training stage when the type of wafer is changed, the templates need to be retrained. This paper proposes a new wafer prealignment algorithm, based on Fourier transform for orientation prealignment and least square regression for position prealignment, which will automatically adapt to different types of wafers in 2-D space. Results from experiments with the proposed algorithm on a laser-scribing machine using two types of wafer show that the orientation prealignment achieved an accuracy of 0.05°, the position prealignment achieved an accuracy of 5 pixels, and the average operation time was approximately 1.5 s. As prealignment algorithm therefore meets real-time efficiency and precision requirements, it is suitable for use with semiconductor devices.Note to Practitioners—Because deviation appears when a wafer is first put on the working table, the traditional process is to set up a prealignment system when aligning a new type of wafer. However, different templates increase difficulty for machine operators, and decrease automation and reliability of the devices. This paper therefore proposes a new general prealignment algorithm based on using Fourier transform for orientation prealignment and least square regression for position prealignment. The algorithm was tested on two types of wafer with results showing that the orientation prealignment achieved an accuracy of 0.05°, the position prealignment achieved an accuracy of 5 pixels, and the average operation time was about 1.5 s, all of which meet real-time requirements. Although the alg- rithm can be adapted to different wafers without adjustment, it does not fit nonquadrilateral chips very well. Accordingly, we will develop an improved algorithm with better generality in due course. Autors: Jiayu Xu;Hong Hu;Yulin Lei;Huaiyuan Liu; Appeared in: IEEE Transactions on Automation Science and Engineering Publication date: Oct 2017, volume: 14, issue:4, pages: 1771 - 1777 Publisher: IEEE
» A Wideband Bandpass Filter With Reconfigurable Bandwidth Based on Cross-Shaped Resonator
 Abstract:A wideband bandpass filter (BPF) with reconfigurable bandwidth (BW) is proposed based on a parallel-coupled line structure and a cross-shaped resonator with open stubs. The p-i-n diodes are used as the tuning elements, which can implement three reconfigurable BW states. The prototype of the designed filter reports an absolute BW tuning range of 1.22 GHz, while the fractional BW is varied from 34.8% to 56.5% when centered at 5.7 GHz. The simulation and measured results are in good agreement. Comparing with previous works, the proposed reconfigurable BPF features wider BW tuning range with maximum number of tuning states. Autors: Teng Cheng;Kam-Weng Tam; Appeared in: IEEE Microwave and Wireless Components Letters Publication date: Oct 2017, volume: 27, issue:10, pages: 909 - 911 Publisher: IEEE
» Absolute Electroluminescence Imaging Diagnosis of GaAs Thin-Film Solar Cells
 Abstract:A spatially resolved absolute electroluminescence (EL) imaging method was utilized to analyze the photovoltaic properties and resistive loss properties of a GaAs thin-film solar cell. The I–V relation was extrapolated from the absolute EL efficiency measurements in conjunction with the external-quantum-efficiency (EQE) measurements; the EL extrapolated I–V relation has a merit over the conventional I–V relation measured with a solar simulator that it could eliminate the series resistance effect caused by external probe contact. Then, the mapping of the internal voltage of the solar cell and the sheet resistance of the window layer of the solar cell were obtained from the calibrated absolute EL imaging method. Finally, optic electroconversion losses of the solar cell including radiative loss, nonradiative loss, thermalization loss, transmission loss, and junction loss were quantified given by the EL and EQE measurements. Autors: XiaoBo Hu;Tengfei Chen;Juanjuan Xue;Guoen Weng;Shaoqiang Chen;Hidefumi Akiyama;Ziqiang Zhu; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 9 Publisher: IEEE
» AC-Inductors Design for a Modular Multilevel TSBC Converter, and Performance of a Low-Speed High-Torque Motor Drive Using the Converter
 Abstract:This paper provides a theoretical and experimental discussion on ac-inductors design for a modular multilevel triple-star bridge-cells (TSBC) converter, or shortly a TSBC converter. This converter requires multiple ac inductors for controlling nine cluster currents. This paper proposes three three-legged, six-winding, “interzigzag” inductors for the TSBC converter. Since each leg of the individual inductor has two windings, the three inductors have 18 windings in total. The wire leads are zigzagged among the three inductors. This unique structure of the “interzigzag” windings leads to the following feature: Both three-phase supply and motor currents produce no magnetic flux in each of the nine legs. This feature makes each inductor smaller in size and lighter in weight. A specially-designed downscaled motor-drive system rated at 400 V and 15 kW is constructed and tested to confirm the validity of a design of the proposed inductors, as well as to verify transient motor-drive performance during four-quadrant operation. Autors: Wataru Kawamura;Makoto Hagiwara;Hirofumi Akagi;Masahiko Tsukakoshi;Ritaka Nakamura;Sumiyasu Kodama; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4718 - 4729 Publisher: IEEE
» Accelerated Shearlet-Domain Light Field Reconstruction
 Abstract:We consider the problem of reconstructing densely sampled light field (DSLF) from sparse camera views. In our previous work, the DSLF has been reconstructed by processing epipolar-plane images (EPI) employing sparse regularization in shearlet transform domain. With the aim to avoid redundant processing and reduce the overall reconstruction time, in this paper, we propose algorithm modifications in three directions. First, we modify the basic algorithm by offering a faster and more stable iterative procedure. Second, we elaborate on the proper use of color redundancy by studying the effect of reconstruction of an average intensity channel and its use as a guiding mode for colorizing the three color channels. Third, we explore similarities between EPIs by their grouping and joint processing or by effective decorrelation to get an initial estimate for the basic iterative procedure. We are specifically interested in GPU-based computations allowing an efficient implementation of the shearlet transform. We quantify our three main approaches to accelerated processing over a wide collection of horizontal as well as full-parallax datasets. Autors: Suren Vagharshakyan;Robert Bregovic;Atanas Gotchev; Appeared in: IEEE Journal of Selected Topics in Signal Processing Publication date: Oct 2017, volume: 11, issue:7, pages: 1082 - 1091 Publisher: IEEE
» Accelerating Recurrent Neural Networks: A Memory-Efficient Approach
 Abstract:Recurrent neural networks (RNNs) have achieved the state-of-the-art performance on various sequence learning tasks due to their powerful sequence modeling capability. However, RNNs usually require a large number of parameters and high computational complexity. Hence, it is quite challenging to implement complex RNNs on embedded devices with stringent memory and latency requirement. In this paper, we first present a novel hybrid compression method for a widely used RNN variant, long–short term memory (LSTM), to tackle these implementation challenges. By properly using circulant matrices, forward nonlinear function approximation, and efficient quantization schemes with a retrain-based training strategy, the proposed compression method can reduce more than 95% of memory usage with negligible accuracy loss when verified under language modeling and speech recognition tasks. An efficient scalable parallel hardware architecture is then proposed for the compressed LSTM. With an innovative chessboard division method for matrix–vector multiplications, the parallelism of the proposed hardware architecture can be freely chosen under certain latency requirement. Specifically, for the circulant matrix–vector multiplications employed in the compressed LSTM, the circulant matrices are judiciously reorganized to fit in with the chessboard division and minimize the number of memory accesses required for the matrix multiplications. The proposed architecture is modeled using register transfer language (RTL) and synthesized under the TSMC 90-nm CMOS technology. With 518.5-kB on-chip memory, we are able to process a compressed LSTM in 1.71 , corresponding to 2.46 TOPS on the uncompressed one, at a cost of 30.77-mm2 chi- area. The implementation results demonstrate that the proposed design can achieve significantly high flexibility and area efficiency, which satisfies many real-time applications on embedded devices. It is worth mentioning that the memory-efficient approach of accelerating LSTM developed in this paper is also applicable to other RNN variants. Autors: Zhisheng Wang;Jun Lin;Zhongfeng Wang; Appeared in: IEEE Transactions on Very Large Scale Integration Systems Publication date: Oct 2017, volume: 25, issue:10, pages: 2763 - 2775 Publisher: IEEE
» Acceleration of the WRF Monin–Obukhov–Janjic Surface Layer Parameterization Scheme on an MIC-Based Platform for Weather Forecast
 Abstract:A state-of-the-art numerical weather prediction (NWP) model, comprising weather research and forecast (WRF) model and analysis techniques, has been extensively exercised for weather prophecy all over the world. The WRF model, the soul role in NWP, constitutes dynamic solvers and elaborate physical components for conducting fluid behavior, all of which are sketched for both atmospheric research analyses and operational weather foretell. One salient physical ingredient in WRF is the surface layer simulation, which provides surface heat and moisture fluxes through calculation of surface friction velocities and exchange coefficients. The Monin–Obukhov–Janjic (MOJ) scheme is one popular surface layer option in WRF. This is one of the schemes in WRF we choose to expedite toward an end-to-end accelerated weather model. One advantageous aspect in WRF is the independence among grid points that facilitates programming implementations in parallel computation. We here present a parallel construction on the MOJ module with application of vectorization elements and efficient parallelization essentials furnished by Intel many integrated core (MIC) architecture. To achieve high computing performance, apart from the fundamental usage of Intel MIC architecture, this paper offers some new approaches related to code structure and art of optimization skills. At the end, in comparison with the original code separately executing on one CPU core and on one CPU socket (eight cores) with Intel Xeon E5-2670, the optimized MIC-based MOJ module running on Xeon Phi coprocessor 7120P ameliorates the computing performance by 9.6× and 1.5×, respectively. Autors: Melin Huang;Bormin Huang;Hung-Lung Allen Huang; Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Publication date: Oct 2017, volume: 10, issue:10, pages: 4399 - 4408 Publisher: IEEE
» Accuracy of Range-Based Cooperative Positioning: A Lower Bound Analysis
 Abstract:Accurate location information is essential for mobile systems such as wireless sensor networks. A location-aware sensor network generally includes two types of nodes: Sensors whose locations to be determined and anchors whose locations are known a priori. For range-based cooperative positioning, sensors’ locations are deduced from anchor-to-sensor and sensor-to-sensor range measurements. Positioning accuracy depends on the network parameters such as network connectivity and size. This paper provides a generalized theory that quantitatively characterizes such a relation between network parameters and positioning accuracy. We use the average degree as a connectivity metric and use geometric dilution of precision (DOP) to quantify positioning accuracy. Under the assumption that nodes are randomly deployed, we prove a novel lower bound on expectation of average geometric DOP (LB-E-AGDOP) and derives a closed-form formula that relates LB-E-AGDOP to only three parameters: Average anchor degree, average sensor degree, and number of sensor nodes. The formula shows that positioning accuracy is approximately inversely proportional to the average degree, and a higher ratio of average anchor degree to average sensor degree yields better positioning accuracy. Furthermore, the paper shows a strong connection between LB-E-AGDOP and the best achievable accuracy. Finally, we demonstrate the theory via numerical simulations with three different random graph models. Autors: Liang Heng;Grace Xingxin Gao; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2304 - 2316 Publisher: IEEE
» Accuracy-Aware Power Management for Many-Core Systems Running Error-Resilient Applications
 Abstract:Power capping techniques based on dynamic voltage and frequency scaling (DVFS) and power gating (PG) are oriented toward power actuation, compromising on performance and energy. Inherent error resilience of emerging application domains, such as Internet-of-Things (IoT) and machine learning, provides opportunities for energy and performance gains. Leveraging accuracy-performance tradeoffs in such applications, we propose approximation (APPX) as another knob for close-looped power management, to complement power knobs with performance and energy gains. We design a power management framework, APPEND+, that can switch between accurate and approximate modes of execution subject to system throughput requirements. APPEND+ considers the sensitivity of the application to error to make disciplined alteration between levels of APPX such that performance is maximized while error is minimized. We implement a power management scheme that uses APPX, DVFS, and PG knobs hierarchically. We evaluated our proposed approach over machine learning and signal processing applications along with two case studies on IoT—early warning score system and fall detection. APPEND+ yields higher throughput, improved latency up to five times, better performance per energy, and dark silicon mitigation compared with the state-of-the-art power management techniques over a set of applications ranging from high to no error resilience. Autors: Anil Kanduri;Mohammad-Hashem Haghbayan;Amir M. Rahmani;Pasi Liljeberg;Axel Jantsch;Hannu Tenhunen;Nikil Dutt; Appeared in: IEEE Transactions on Very Large Scale Integration Systems Publication date: Oct 2017, volume: 25, issue:10, pages: 2749 - 2762 Publisher: IEEE
» Accuracy-Enhanced Algorithms for the Slot Leakage Inductance Computation of Double-Layer Windings
 Abstract:The paper presents original developments concerning the analytical computation of the slot leakage inductive parameters referring to unsaturated rotating electrical machines. In particular, the double-layer winding layout and arbitrary-shaped semi-closed slots are considered. The conventional analytical formulations of the self- and mutual-inductances of the two layers are initially presented, together with the algorithm developed for their computations. Then, the error causes laying on the simplifying assumptions are discussed and two corrections are applied to the conventional equations to enhance their accuracy with respect to finite element method estimations. Numerical examples of the magnetic energy stored in several slot geometrical domains are included in order to show the potentialities of the proposed analytical approach. Autors: Andrea Cavagnino; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4422 - 4430 Publisher: IEEE
» Accurate and Efficient Approximation of Clothoids Using Bézier Curves for Path Planning
 Abstract:An accurate and efficient clothoid approximation approach is presented in this paper using Bézier curves based on the minimization of curvature profile difference. Compared with existing methods, the proposed approach is able to guarantee higher order geometric continuity with smaller approximation error in terms of position, orientation, and curvature. The approximation scheme takes place in three stages. First, a subset of clothoids with specific winding angle constraints referred to as elementary clothoids is approximated using quintic Bézier curves. Then, a basic clothoid defined in the first quadrant is formulated, which is composed of a series of transformed elementary clothoids. An adaptive sampling stra-tegy is applied to ensure that the resulting Bézier segments are computed within a specified accuracy and all the required information can be obtained offline and stored in a lookup table. Finally, a general clothoid with arbitrary parameters can be conveniently approximated based on the lookup table through appropriate geometric transformations. A comparison with the recent circular interpolation and rational Bézier curve based approximation shows that the proposed approach is able to achieve equivalent or greater computational efficiency in most scenarios. Autors: Yong Chen;Yiyu Cai;Jianmin Zheng;Daniel Thalmann; Appeared in: IEEE Transactions on Robotics Publication date: Oct 2017, volume: 33, issue:5, pages: 1242 - 1247 Publisher: IEEE
» Accurate Closed-Form Expressions for the Bit Rate-Wireless Transmission Distance Relationship in IR-UWBoF Systems
 Abstract:Efficient utilization of the extremely limited available power of impulse radio ultrawideband (IR-UWB) waveforms can significantly extend their wireless reach in the wireless transmission chain of IR-UWB over fiber (IR-UWBoF) systems. In this letter, the two most common types of photonically generated IR-UWB waveforms are considered and accurate closed-form analytical expressions for the bit rate—distance relationship in the wireless transmission chain of IR-UWBoF systems are developed. These analytical expressions are verified by simulations and optimized such that the wireless transmission distance of IR-UWB waveforms is maximized under the Federal Communications Commission spectral constraints. Autors: Mohamed Shehata;Hassan Mostafa;Yehea Ismail; Appeared in: IEEE Communications Letters Publication date: Oct 2017, volume: 21, issue:10, pages: 2138 - 2141 Publisher: IEEE
» Accurate Insect Orientation Extraction Based on Polarization Scattering Matrix Estimation
 Abstract:A novel insect orientation extraction method is proposed based on the target polarization scattering matrix (PSM) estimation, which is applicable for traditional vertical-looking insect radar with noncoherent reception as well as the coherent radar. The insect echo signal at different polarization directions on the radar polarization plane is usually acquired by means of rotating linearly polarized antenna. In this letter, the insect echo signal is first used to accurately estimate insect PSM by an iterative algorithm based on the second-order polynomial approximation. Meanwhile, the Cramer–Rao lower bound is also analyzed to test the estimation performance. Next, based on the assumption that the target orientation is consistent with the dominant eigenvector, the insect orientation is extracted from the estimated PSM. Finally, both theoretical simulations and real experimental data are used to validate the effectiveness and feasibility of our proposed method, which can achieve good orientation estimation accuracy at low signal-to-noise ratio. Autors: C. Hu;W. Li;R. Wang;C. Liu;T. Zhang;W. Li; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Oct 2017, volume: 14, issue:10, pages: 1755 - 1759 Publisher: IEEE
» Accurate Reduced Dimensional Polynomial Chaos for Efficient Uncertainty Quantification of Microwave/RF Networks
 Abstract:This paper presents a polynomial chaos (PC) formulation based on the concept of dimension reduction for the efficient uncertainty analysis of microwave and RF networks. This formulation exploits a high-dimensional model representation for quantifying the relative effect of each random dimension on the network responses surface. This information acts as problem-dependent sensitivity indices guiding the intelligent identification and subsequent pruning of the statistically unimportant random dimensions from the original parametric space. Performing a PC expansion in the resultant low-dimensional random subspace leads to the recovery of a sparser set of coefficients than that obtained from the full-dimensional random space with negligible loss in accuracy. Novel methodologies to reuse the preliminary PC bases and SPICE simulations required to estimate the sensitivity indices are presented, thereby making the proposed approach more efficient and accurate than standard sparse PC approaches. The validity of the proposed approach is demonstrated using three distributed network examples. Autors: Aditi Krishna Prasad;Sourajeet Roy; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Oct 2017, volume: 65, issue:10, pages: 3697 - 3708 Publisher: IEEE
» Accurate Solution of Electromagnetic Scattering by Super-Thin Conducting Objects Based on Magnetic Field Integral Equation
 Abstract:Electromagnetic scattering by super-thin conducting objects is formulated by integral equation approach. It could be difficult to obtain accurate solutions for such a problem because the current density changes dramatically near the edges of such objects and many low-quality meshes exist on the side faces of objects when discretized. Traditionally, the electric field integral equation is used to describe the problem and the three-dimensional (3-D) objects are approximated as a two-dimensional (2-D) open structure with a summation of the current density at two opposite sides. In this communication, the magnetic field integral equation (MFIE) is employed to govern the problem and the super-thin objects are strictly treated as 3-D objects. The MFIE is a second-kind integral equation resulting in a better conditioning and can also release the low-frequency breakdown problem, but it has not been applied to very thin structures. In the method of moments solution, a robust near-singularity treatment for its kernel is developed based on the Green’s lemma. The derived formulations are friendly and very suitable for low-quality triangular meshes. Numerical examples are presented to demonstrate the scheme and good results have been obtained. Autors: Mei Song Tong;Xiao Jia Huang; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5633 - 5638 Publisher: IEEE
» Achievable DoF Regions of MIMO Networks With Imperfect CSIT
 Abstract:We focus on a two-receiver multiple-input-multiple-output (MIMO), broadcast channel (BC), and interference channel (IC) with an arbitrary number of antennas at each node. We assume an imperfect knowledge of local channel state information at the transmitters, whose error decays with the signal-to-noise-ratio. With such configuration, we characterize the achievable degrees-of-freedom (DoF) regions in both BC and IC, by proposing a rate-splitting (RS) approach, which divides each receiver’s message into a common part and a private part. Compared with the RS scheme designed for the symmetric MIMO case, the novelties of the proposed block lie in: 1) delivering additional non-ZF-precoded private symbols to the receiver with the greater number of antennas and 2) a space-time implementation. These features provide more flexibilities in balancing the common-message-decodabilities at the two receivers, and fully exploit asymmetric antenna arrays. Besides, in IC, we modify the power allocation designed for the asymmetric BC based on the signal space, where the two transmitted signals interfere with each other. We also derive an outer-bound for the DoF regions and show that the proposed achievable DoF regions are optimal under some antenna configurations and channel state information at the transmitter side qualities. Autors: Chenxi Hao;Borzoo Rassouli;Bruno Clerckx; Appeared in: IEEE Transactions on Information Theory Publication date: Oct 2017, volume: 63, issue:10, pages: 6587 - 6606 Publisher: IEEE
» Achievable Rates in Uplink Massive MIMO Systems With Pilot Hopping
 Abstract:Massive MIMO promises large spectral and power efficiency gains. However, pilot contamination limits these aspired gains. In this paper, we propose a structured, i.e., non-random, pilot hopping and a weighted moving average channel estimation for time-varying massive MIMO systems. The proposed algorithm diversifies the contaminating (interfering) sources, such that all the users enjoy the hopping advantages. We analyze the performance of multi-cell network, where the base stations perform matched filtering or zero-forcing for data detection. Using polynomial expansion approximations, we obtain achievable rates that are tight even at finite (not very large) number of antennas. It is shown that the spectral efficiency gain achieved by pilot hopping is not a monotonic function of the pilot reuse factor in some cases and, therefore, brings to attention that careful cell planning is required when applying pilot hopping. Moreover, the proposed algorithm involves a weighted moving average that uses the previously obtained channel estimates (of the preceding blocks) if they are correlated with the current one. Due to the massive MIMO properties, the algorithm is robust to channel time-variations and can be used with any previously proposed channel estimation method. Autors: Ahmed S. Alwakeel;Ahmed Mohammed Hesham Mehana; Appeared in: IEEE Transactions on Communications Publication date: Oct 2017, volume: 65, issue:10, pages: 4232 - 4246 Publisher: IEEE

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