#### Electrical and Electronics Engineering publications abstract of: 09-2017 sorted by title, page: 3

» An Empirical Study on the Effect of Testing on Code Quality Using Topic Models: A Case Study on Software Development Systems
 Abstract:Previous research in defect prediction has proposed approaches to determine which files require additional testing resources. However, practitioners typically create tests at a higher level of abstraction, which may span across many files. In this paper, we study software testing, especially test resource prioritization, from a different perspective. We use topic models to generate topics that provide a high-level view of a system, allowing developers to look at the test case coverage from a different angle. We propose measures of how well tested and defect prone a topic is, allowing us to discover which topics are well tested and which are defect prone. We conduct case studies on the histories of Mylyn, Eclipse, and NetBeans. We find that 34–78% of topics are shared between source code and test files, indicating that we can use topic models to study testing; well-tested topics are usually less defect prone, defect-prone topics are usually undertested; we can predict which topics are defect prone but not well tested with an average precision and recall of 75% and 77%, respectively; our approach complements traditional prediction-based approaches by saving testing and code inspection effort; and our approach is not particularly sensitive to the parameters that we use. Autors: Tse-Hsun Chen;Stephen W. Thomas;Hadi Hemmati;Meiyappan Nagappan;Ahmed E. Hassan; Appeared in: IEEE Transactions on Reliability Publication date: Sep 2017, volume: 66, issue:3, pages: 806 - 824 Publisher: IEEE
» An FSS Structure With Geometrically Separable Meander-Line Inductors and Parallel-Plate Capacitors
 Abstract:A frequency selective surface (FSS) structure with geometrically separable meander-line inductors (MLIs) and parallel-plate capacitors (PPCs) is proposed. For this FSS structure, the filtering responses for different polarizations and resonance frequencies are realized through separate subcells. For example, to achieve a single-band bandpass performance, two subcells, acting as parallel LC resonators for transverse-electric and transverse-magnetic polarizations, respectively, are implemented by MLIs and PPCs. Because the MLIs and PPCs provide increased equivalent inductance and capacitance, respectively, this FSS provides a miniaturized unit cell size of refers to the resonance wavelength), and its −3 dB bandwidth can be designed by independently adjusting the equivalent inductance and capacitance. A design example shows the easy control of −3 dB bandwidth ranging from 13.6% to 49% with respect to the center frequency. Furthermore, because of the separable subcells, the FSS performances for different polarizations are independently controllable, and it can be readily extended to achieve dual-band bandpass performance with a band ratio ranging from 1.35 to 3.8. In addition, to model the FSS frequency performance precisely, equivalent circuits and closed forms are developed, which serve as a substitute for commercial software for efficient FSS design. Finally, some prototypes are fabricated and measured. All the measured results show that the proposed FSS designs exhibit stable performance under different polarizations and incidence angles (up to 60°), and they exhibit good consistency with those from the full-wave simulations. Autors: Peng-Chao Zhao;Zhi-Yuan Zong;Wen Wu;Bo Li;Da-Gang Fang; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Sep 2017, volume: 65, issue:9, pages: 4693 - 4705 Publisher: IEEE
» An Image Reconstruction Algorithm for Electrical Impedance Tomography Using Adaptive Group Sparsity Constraint
 Abstract:Image quality has long been deemed a key challenge for electrical impedance tomography (EIT). High-quality image is of great significance for improving the qualitative and quantitative imaging performance in biomedical or industrial applications. In this paper, a novel image reconstruction algorithm for EIT using adaptive group sparsity constraint is proposed to obtain enhanced image quality. The proposed algorithm takes both the underlying structure characteristics and sparsity prior of the conductivity distribution into account to promote a solution with group sparsity structure and reduce the degree of freedom. Specifically, an adaptive grouping method is incorporated for efficient and dynamic pixel grouping when the conductivity distribution does not have a fixed structure or the prior knowledge of the structure is unavailable. Numerical simulation and phantom experiments are performed to validate the proposed algorithm. The results are compared with those using the Landweber iteration, total variation regularization, and regularization. Both simulation and experiment results confirm the significantly improved tomographic imaging quality using the proposed algorithm, which demonstrates great potential for multiphase flow imaging and biological tissue imaging. Autors: Yunjie Yang;Jiabin Jia; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Sep 2017, volume: 66, issue:9, pages: 2295 - 2305 Publisher: IEEE
» An Improved Arc Flash Energy Calculation Method and Its Application
 Abstract:In this paper, we describe an improved algorithm for arc flash calculations. This method can be used in any software that performs arc flash calculations to determine the incident energy, arc flash boundaries, and other related parameters for arc flash risk assessment purposes. The method provides a more sophisticated and precise way of calculating short circuit contributions to the fault location. To illustrate the effectiveness of the method, a typical renewable power plant (wind energy) with common types of protection is analyzed. The arc flash risk assessment results are compared in both the conventional way and the presented method. The new approach is called the Integrated Method. This method is an accurate way of modelling the short circuit contribution of the devices, which can potentially change the total short circuit current at the fault location. This Integrated Method considers the decay of the contributing machines and the devices where currents are interrupted due to a protection device. It also accounts for the current decays over time. Autors: Afshin Majd;Robert Luo; Appeared in: IEEE Transactions on Industry Applications Publication date: Sep 2017, volume: 53, issue:5, pages: 5062 - 5067 Publisher: IEEE
» An Improved DAQ-Based Method for Ferrite Characterization
 Abstract:In this paper, we propose an improved version of the classical volt-amperometric measurement method for the characterization of magnetic hysteresis and losses in soft magnetic cores. Using an appropriate circuital solution for the automatic cancellation of the measurement offset and a synchronous data-acquisition-based scheme for both generation and acquisition of signals, we are able to implement a high performance and low error fully automatic test system. This reduces the testing time, while allowing the use of new segmentation algorithms for the study of both major and minor hysteresis loops and the extraction of all the desired properties. We tested the system on a ferrite core, reproducing results already known from the literature with a higher degree of accuracy and reliability, and propose a test to assess the limits of applicability of the method. Energetic magnetic behavior during the formation of asymmetric minor loops is shown and discussed throughout this paper. Autors: Carlo Guarnieri Calò Carducci;Mirko Marracci;Filippo Attivissimo;Romano Giannetti;Bernardo Tellini; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Sep 2017, volume: 66, issue:9, pages: 2413 - 2421 Publisher: IEEE
» An Improved Delayed Signal Cancellation PLL for Fast Grid Synchronization Under Distorted and Unbalanced Grid Condition
 Abstract:Cascasded delayed signal cancellation (DSC) phase-locked loop (PLL) technique has been attractive for grid synchronization under nonideal grid voltage due to its good harmonics filtering capability. However, it has to face the challenge of slow dynamic response. In this paper, an improved DSC-PLL that features high filtering capability, fast dynamic response and simple structure is presented. This PLL employs only one DSC block and one moving average filter (MAF) block to eliminate all even-order and odd-order harmonics while a second-order phase lead compensator and q-axis feedforward path are introduced to increase the PLL bandwidth. The effect of the phase lead compensator on PLL dynamic performance is analyzed. The feedforward path works only when grid voltage frequency or phase jumps and will not affect the steady state behaviors. Therefore, the PLL can improve the phase estimation accuracy and dynamic speed at the same time even under highly distorted and unbalanced grid voltage. Moreover, linear Lagrange interpolation method is adopted to reduce the discretized errors in the digital implementation of the PLL. The effectiveness of the proposed method is validated by both simulation and experimental results. The comparison results with the existing cascaded DSC-PLL and standard MAF-PLL are also presented. Autors: Qicheng Huang;Kaushik Rajashekara; Appeared in: IEEE Transactions on Industry Applications Publication date: Sep 2017, volume: 53, issue:5, pages: 4985 - 4997 Publisher: IEEE
» An Improved DPA Countermeasure Based on Uniform Distribution Random Power Generator for IoT Applications
 Abstract:In order to secure the communication in Internet of Things era, a low overhead power analysis countermeasure called uniform distribution random power generator is proposed for stream ciphers. To alter the power signature of protected circuit, ring oscillators, which act as unit power generators, are grouped in a systematic approach to generate additional power with uniform probability distribution. Experiments from the proposed evaluation framework demonstrate that the secret key of unprotected device can be disclosed within 103 power traces with standard differential power analysis attack, whereas the same attack mounted on the proposed scheme cannot be disclosed even after 106 measurements. Moreover, the area and the power overhead are reduced by at least 29% and 22% compared with the state-of-the-art works, respectively. Autors: Szu-Chi Chung;Chun-Yuan Yu;Sung-Shine Lee;Hsie-Chia Chang;Chen-Yi Lee; Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers Publication date: Sep 2017, volume: 64, issue:9, pages: 2522 - 2531 Publisher: IEEE
» An Improved Fuzzy Neural Network for Traffic Speed Prediction Considering Periodic Characteristic
 Abstract:This paper proposes a new method in construction fuzzy neural network to forecast travel speed for multi-step ahead based on 2-min travel speed data collected from three remote traffic microwave sensors located on a southbound segment of a fourth ring road in Beijing City. The first-order Takagi–Sugeno system is used to complete the fuzzy inference. To train the evolving fuzzy neural network (EFNN), two learning processes are proposed. First, a -means method is employed to partition input samples into different clusters and a Gaussian fuzzy membership function is designed for each cluster to measure the membership degree of samples to the cluster centers. As the number of input samples increases, the cluster centers are modified and membership functions are also updated. Second, a weighted recursive least squares estimator is used to optimize the parameters of the linear functions in the Takagi–Sugeno type fuzzy rules. Furthermore, a trigonometric regression function is introduced to capture the periodic component in the raw speed data. Specifically, the predicted performance between the proposed model and six traditional models are compared, which are artificial neural network, support vector machine, autoregressive integrated moving average model, and vector autoregressive model. The results suggest that the prediction performances of EFNN are better than those of traditional models due to their strong learning ability. As the prediction time step increases, the EFNN model can consider the periodic pattern and demonstrate advantages over other models with smaller predicted errors and slow raising rate of errors. Autors: Jinjun Tang;Fang Liu;Yajie Zou;Weibin Zhang;Yinhai Wang; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Sep 2017, volume: 18, issue:9, pages: 2340 - 2350 Publisher: IEEE
» An Improved Method of DC Bus Voltage Pulsation Suppression for Asymmetric Wind Power PMSG Systems With a Compensation Unit in Parallel
 Abstract:This paper proposes an improved method of simultaneously suppressing the second harmonic (2h) dc-bus voltage pulsation and torque ripple by a compensation unit in parallel with the dc bus in the wind power permanent magnet synchronous generator (PMSG) system with asymmetric impedance. Compared to the existing methods, the proposed method uses fewer power devices and requires a much lower compensation current. These results in a lower power rating, lower power switch and copper losses, and a smaller compensation inductor in the compensation unit. In addition, the corresponding compensation current control is much simpler to operate. Overall, it is an effective method of suppressing the 2h dc bus voltage, although a dc voltage source is required in the compensation unit. The compensation effectiveness has been experimentally verified on a prototype asymmetric PMSG with inherent asymmetry and deliberately introduced asymmetries. Autors: Yashan Hu;Zi Qiang Zhu;Milijana Odavic; Appeared in: IEEE Transactions on Energy Conversion Publication date: Sep 2017, volume: 32, issue:3, pages: 1231 - 1239 Publisher: IEEE
» An Indoor Wayfinding System Based on Geometric Features Aided Graph SLAM for the Visually Impaired
 Abstract:This paper presents a 6-degree of freedom (DOF) pose estimation (PE) method and an indoor wayfinding system based on the method for the visually impaired. The PE method involves two-graph simultaneous localization and mapping (SLAM) processes to reduce the accumulative pose error of the device. In the first step, the floor plane is extracted from the 3-D camera’s point cloud and added as a landmark node into the graph for 6-DOF SLAM to reduce roll, pitch, and errors. In the second step, the wall lines are extracted and incorporated into the graph for 3-DOF SLAM to reduce , , and yaw errors. The method reduces the 6-DOF pose error and results in more accurate pose with less computational time than the state-of-the-art planar SLAM methods. Based on the PE method, a wayfinding system is developed for navigating a visually impaired person in an indoor environment. The system uses the estimated pose and floor plan to locate the device user in a building and guides the user by announcing the points of interest and navigational commands through a speech interface. Experimental results validate the effectiveness of the PE method and demonstrate that the system may substantially ease an indoor navigation task. Autors: He Zhang;Cang Ye; Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering Publication date: Sep 2017, volume: 25, issue:9, pages: 1592 - 1604 Publisher: IEEE
» An Inductive and Capacitive Integrated Coupler and Its LCL Compensation Circuit Design for Wireless Power Transfer
 Abstract:This paper proposes a novel coupler structure for wireless power transfer, which takes advantage of both magnetic and electric fields. The coupler contains four metal structures, two each at the primary and secondary sides, which are capacitively coupled. Each structure consists of long strips of metal sheet to increase its self-inductance, which is then inductively coupled with the other three structures. The structures are vertically arranged and the outer structures are larger than the inner ones to maintain the capacitive couplings. An external LCL compensation network is proposed to resonate with the coupler. The resonance provides conduction currents flowing through each plate to establish magnetic fields and displacement currents flowing between different plates corresponding to electric fields. A 100-W output power prototype is designed and implemented to operate at 1.0 MHz, and it achieves 73.6% efficiency from dc source to dc load across an air-gap distance of 18 mm. The contribution of this paper is to propose a concept to transfer power using magnetic and electric fields simultaneously. Autors: Fei Lu;Hua Zhang;Heath Hofmann;Chunting Chris Mi; Appeared in: IEEE Transactions on Industry Applications Publication date: Sep 2017, volume: 53, issue:5, pages: 4903 - 4913 Publisher: IEEE
» An Inductive Power Transfer System Supplied by a Multiphase Parallel Inverter
 Abstract:The output power of a single-phase inverter is insufficient for high-power applications, such as fast wireless chargers for electrical vehicles. A higher power level can be obtained via a multiphase parallel resonant inverter, which comes with a possible cost of the unbalance current problem. Coupled inductors with a cyclic cascade connection instead of a complex controller are employed to alleviate this problem. A blocking capacitor is introduced to stop the dc component of the circulating current. Equations for suppressing ability of circulating currents under the proposed topology with various numbers of parallel phases are derived. Main power loss components are analyzed and the reason why multiphase systems with a high output current have a higher efficiency is theoretically explained. A prototype of an inverter with six-phase half-bridge parallel topology is developed and built to verify the theoretical analysis. The prototype is used to supply an inductive power transfer system, which delivers power at a distance of 20 cm. When the receiving power of the 6.87 Ω load in the rectifier is 20 kW, one obtains a 95.6% efficiency measured as the power of the dc-load divided by that of dc-input at the inverter. Autors: Qijun Deng;Jiangtao Liu;Dariusz Czarkowski;Wenshan Hu;Hong Zhou; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Sep 2017, volume: 64, issue:9, pages: 7039 - 7048 Publisher: IEEE
» An Inequality on Source-to-Sink Average BER and Its Application on Wireless Sensor Networks
 Abstract:This letter drives a novel inequality expression on source-to-sink average BER (S2S-ABER) for multi-hop communication in a network. The obtained expression is less complex and can be implemented on computationally constraint devices, such as sensor nodes. Moreover, it has been applied to wireless sensor networks to determine the SNR limitations such that S2S-ABER does not exceed a threshold value. This information is helpful in deciding the optimum route between source and sink for reliable data dissemination. Although each route can undergo multiple combinations of channel distributions, a typical case with two different scenarios has been considered in this letter for simplicity. Autors: Ashish Goswami;Ashok Kumar; Appeared in: IEEE Communications Letters Publication date: Sep 2017, volume: 21, issue:9, pages: 2077 - 2080 Publisher: IEEE
» An Information-Theoretic Study for Joint Sparsity Pattern Recovery With Different Sensing Matrices
 Abstract:In this paper, we study a support set reconstruction problem for multiple measurement vectors (MMV) with different sensing matrices, where the signals of interest are assumed to be jointly sparse and each signal is sampled by its own sensing matrix in the presence of noise. Using mathematical tools, we develop upper and lower bounds of the failure probability of the support set reconstruction in terms of the sparsity, the ambient dimension, the minimum signal-to-noise ratio, the number of measurement vectors, and the number of measurements. These bounds can be used to provide guidelines for determining the system parameters for various compressed sensing applications with noisy MMV with different sensing matrices. Based on the bounds, we develop necessary and sufficient conditions for reliable support set reconstruction. We interpret these conditions to provide theoretical explanations regarding the benefits of taking more measurement vectors. We then compare our sufficient condition with the existing results for noisy MMV with the same sensing matrix. As a result, we show that noisy MMV with different sensing matrices may require fewer measurements for reliable support set reconstruction, under a sublinear sparsity regime in a low noise-level scenario. Autors: Sangjun Park;Nam Yul Yu;Heung-No Lee; Appeared in: IEEE Transactions on Information Theory Publication date: Sep 2017, volume: 63, issue:9, pages: 5559 - 5571 Publisher: IEEE
» An Integrated Dual-Mode CMOS Power Amplifier With Linearizing Body Network
 Abstract:A dual-mode radio frequency CMOS power amplifier (PA) for Internet of Things application is presented, which is integrated with the other circuits in a 55-nm bulk CMOS process. The low-power mode is achieved by reducing the number of turn-on power transistors, which are also used for linearization. The PA has a gain control scheme that functions by controlling the transconductance () of the driver stage. A simple body network is introduced to common gate power transistors to improve the linearity of the PA. It is measured with 802.11n 64-quadrature-amplitude-modulation (MCS7) signal and shows a maximum average power of 16 dBm with a supply current of 222 mA under an error-vector-magnitude of −27 dB, which is packaged in a QFN 5 mm. Autors: Gwanghyeon Jeong;Seunghoon Kang;Taehwan Joo;Songcheol Hong; Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs Publication date: Sep 2017, volume: 64, issue:9, pages: 1037 - 1041 Publisher: IEEE
» An Integrated Examination of AMSR2 Products Over Ocean
 Abstract:Integrated processing and analysis are presented for oceanic retrievals of precipitation, sea ice concentration, columnar water vapor and cloud water, sea surface temperature, and near-surface wind from the advanced microwave scanning radiometer-2 (AMSR2) sensor. By developing a common algorithmic framework and permitting iterative interaction between historically separate science algorithms, ambiguous and contradictory retrieval results are minimized. The integration also serves to improve each algorithm individually, decreasing reliance on ancillary datasets. Case studies are presented that exemplify both ongoing challenges for these retrievals and potential research uses of such an integrated satellite product. Two cases are presented each for precipitation at high latitudes and marginal sea ice detection, with analysis supplemented by satellite data from CloudSat profiles and Himawari-8 imagery. Detection and retrieval of snowfall remains a challenge, while light rainfall detection can be aided by a variational algorithm. Sea ice concentrations below 20% cause disagreements, but the algorithms otherwise agree well on the sea ice edge. Potential mitigation strategies for ambiguous areas of light rainfall and marginal sea ice are discussed. The analysis demonstrates potential avenues for future algorithm development, but also some physical limitations of remote sensing with the AMSR2 frequencies. Autors: David Ian Duncan;Christian D. Kummerow;Walter N. Meier; Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Publication date: Sep 2017, volume: 10, issue:9, pages: 3963 - 3974 Publisher: IEEE
» An Interval Approach to Nonlinear Controller Design for Load-Following Operation of a Small Modular Pressurized Water Reactor
 Abstract:A pressurized water reactor (PWR) is most suitable for load-following operation because of its self-regulating nature. However, rapid power maneuvering at an enhanced rate is heavily constrained by the overall power coefficient of reactivity which depends on both the reactor neutronics and thermal hydraulics. In this paper, a 100 MWe PWR module with an integrated steam generator, is modeled using the nonlinear equations representing both the neutronics and thermal hydraulics. Such a PWR is typically an integrated structure with a steam generator included in the same casing and can either be connected to the grid or connected with other such modules using a multimodular approach to constitute a Nuclear Steam Supply System (NSSS) driving a common turbine and an alternator. In this paper, Nonlinear Dynamic Inversion (NDI) technique is used to design a controller capable of controlling such a reactor for load-following with frequent changes in demand, in both the modes of operation, namely, reactor-follow-turbine and turbine-follow-reactor. With the assumption that the parameters of the reactor vary within intervals as the power varies, an interval approach coupled with NDI ensures that the controller satisfies the operating constraints. The methodology is established for both the modes with credible real-time Hardware-in-Loop (HiL) simulations. Autors: Debayan Bose;Shohan Banerjee;M. Kumar;P. P. Marathe;Siddhartha Mukhopadhyay;Amitava Gupta; Appeared in: IEEE Transactions on Nuclear Science Publication date: Sep 2017, volume: 64, issue:9, pages: 2474 - 2488 Publisher: IEEE
» An Introduction to an Algorithm for Extracting Precipitable Water Vapor Over Land From AMSR2 Images
 Abstract:Accurate estimation of atmospheric precipitable water vapor (PWV) with high spatial and temporal resolutions is challenging. The main objective of this study is to develop an algorithm of retrieving PWV from advanced microwave scanning radiometer 2 (AMSR2) images over the land using local data. In this regard, the western part of Iran was selected as the study area and one-year period including 80 days of four seasons since 2015 to 2016 was utilized as training and testing days. Brightness temperatures from 18.7-, 23.8-, 36.5-, and 89-GHz channels of AMSR2 in horizontal and vertical polarizations were used for implementations. Moreover, reflectance of bands 1 and 2 of moderate resolution imaging spectroradiometer was used to investigate vegetation cover conditions. Six radiosonde stations of Tehran, Tabriz, Kermanshah, Ahvaz, Shiraz, and Isfahan in the study area were used as ground truth data. Then, seven experiments were conducted, which two first implementations were done using proposed algorithms for AMSR-E and AMSR-2 sensors over the land. In the five other experiments, the influences of cloud liquid water, land surface temperature, and ground elevation were considered in the measured brightness temperatures. In the fourth to seventh experiments, the normalized-difference vegetation index was imported as a linear, quadratic, power, and exponential parameter in the equation of PWV extraction, respectively. Based on the validation results, the best correlation was observed in the sixth experiment so that the coefficient of determination (R2), RMSE, and the ratio RMSE/STD were 0.648, 3.891 mm, and 0.6, respectively. Autors: Mohammad Hossein Merrikhpour;Majid Rahimzadegan; Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Publication date: Sep 2017, volume: 10, issue:9, pages: 3975 - 3984 Publisher: IEEE
» An Investigation of High-Temperature (to 300 °C) Safe-Operating-Area in a High-Voltage Complementary SiGe on SOI Technology
 Abstract:Safe-operating-area (SOA) in a high-voltage complementary silicon–germanium (SiGe) (= n-p-n + p-n-p) on silicon-on-insulator (SOI) technology is investigated from 24 °C to 300 °C. Three key reliability degradation regions are identified, including: 1) high-current; 2) mixed-mode; and 3) high-power. The degradation mechanisms, which are operative, including Auger damage, mixed-mode damage, and electrothermal runaway as well as their temperature dependences are identified. Mixed-mode damage exhibits a strong negative temperature coefficient for both n-p-n and p-n-p SiGe heterojunction bipolar transistors (HBTs) up to 300 °C, which leads to an increase in the SOA from a high-voltage perspective. Electrothermal boundaries are also explored by finding and across the – plane up to 300 °C. Both n-p-n and p-n-p SiGe HBTs show an increase in the SOA for the electrothermal boundary as temperature increases. High-current-induced damage, on the other hand, exhibits a positive temperature coefficient, which implies that high current drive should carefully be considered when using SiGe HBT circuits operated in a high-temperature environment. However, at very high temperatures (>200°C), the high current damage processes show annealing properties, which implies that at sufficiently high temperatures, annealing can dominate over Auger damage and potentially extend the SOA of the technolo- y. Autors: Anup P. Omprakash;Ha Dao;Uppili S. Raghunathan;Hanbin Ying;Partha S. Chakraborty;Jeffrey A. Babcock;Rajarshi Mukhopadhyay;John D. Cressler; Appeared in: IEEE Transactions on Electron Devices Publication date: Sep 2017, volume: 64, issue:9, pages: 3748 - 3755 Publisher: IEEE
» An IoT Endpoint System-on-Chip for Secure and Energy-Efficient Near-Sensor Analytics
 Abstract:Near-sensor data analytics is a promising direction for internet-of-things endpoints, as it minimizes energy spent on communication and reduces network load - but it also poses security concerns, as valuable data are stored or sent over the network at various stages of the analytics pipeline. Using encryption to protect sensitive data at the boundary of the on-chip analytics engine is a way to address data security issues. To cope with the combined workload of analytics and encryption in a tight power envelope, we propose Fulmine, a system-on-chip (SoC) based on a tightly-coupled multi-core cluster augmented with specialized blocks for compute-intensive data processing and encryption functions, supporting software programmability for regular computing tasks. The Fulmine SoC, fabricated in 65-nm technology, consumes less than 20mW on average at 0.8V achieving an efficiency of up to 70pJ/B in encryption, 50pJ/px in convolution, or up to 25MIPS/mW in software. As a strong argument for real-life flexible application of our platform, we show experimental results for three secure analytics use cases: secure autonomous aerial surveillance with a state-of-the-art deep convolutional neural network (CNN) consuming 3.16pJ per equivalent reduced instruction set computer operation, local CNN-based face detection with secured remote recognition in 5.74pJ/op, and seizure detection with encrypted data collection from electroencephalogram within 12.7pJ/op. Autors: Francesco Conti;Robert Schilling;Pasquale Davide Schiavone;Antonio Pullini;Davide Rossi;Frank Kağan Gürkaynak;Michael Muehlberghuber;Michael Gautschi;Igor Loi;Germain Haugou;Stefan Mangard;Luca Benini; Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers Publication date: Sep 2017, volume: 64, issue:9, pages: 2481 - 2494 Publisher: IEEE
» An Isolated/Bidirectional PWM Resonant Converter for V2G(H) EV On-Board Charger
 Abstract:This paper suggests another candidate for isolated/bidirectional dc/dc converter in electric vehicle on-board charger based on PWM resonant converter (RC). The PWM-RC has good switching characteristics but it is not adequate for bidirectional applications because it is always operated under “buck type” operation regardless of power flow directions. This problem can be solved by structure change method, which increases the converter gain into double. Also, additional technique to increase the converter gain during discharging operation is suggested by analysis of the gain characteristics. The feasibility of bidirectional PWM-RC is verified with a 6.6-kW prototype charger. Autors: Byung-Kwon Lee;Jong-Pil Kim;Sam-Gyun Kim;Jun-Young Lee; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Sep 2017, volume: 66, issue:9, pages: 7741 - 7750 Publisher: IEEE
» An Iterative Design Procedure for Multiband Single-Layer Reflectarrays: Design and Experimental Validation
 Abstract:A novel iterative procedure for designing multiband single-layer reflectarrays is presented. The multiband frequency behavior is achieved by simultaneously providing the desired phases at each operating frequency. A suitable reflectarray element shape formed by several concentric loops loaded with double stubs has been selected for achieving multiband operation. The problem of mutual coupling among the different self-similar resonating elements laying on the same substrate is analyzed and mitigated by employing an innovative iterative design approach. The proposed design approach is demonstrated by designing a tri-band single-layer reflectarray with widely spaced frequencies operating at 3.9 GHz (C-band), 7.5 GHz (X-band), and 12.5 GHz (Ku-band). The single-layer prototype is compact and lightweight as it has been fabricated on a thin Kapton film glued on to a Rohacell HF31 substrate. The overall thickness is approximately /5 at the highest operative frequency. Measurements of the reflectarray radiation patterns agree with the estimated performance and prove the reliability of the proposed synthesis technique. Autors: Michele Borgese;Filippo Costa;Simone Genovesi;Agostino Monorchio; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Sep 2017, volume: 65, issue:9, pages: 4595 - 4606 Publisher: IEEE
» An LC-Compensated Electric Field Repeater for Long-Distance Capacitive Power Transfer
 Abstract:This paper proposes an LC-compensated electric field repeater to extend the transfer distance of a capacitive power transfer (CPT) system. The repeater contains two metal plates connected with an external capacitor and an external inductor. The plates are used to generate electric fields to transfer power. The external inductor and capacitor are used to resonate with the plates in order to increase the voltage levels. The repeater is placed between a transmitter and a receiver, which also contains metal plates compensated by an LC network. The repeater can increase the transfer distance of the CPT system without significantly influencing the system power and efficiency. In this paper, the capacitive coupler structure and dimensions are designed and simulated using Maxwell software. Considering all the capacitive coupling between plates, an equivalent circuit model is derived. The fundamental harmonics approximation method is used to analyze the working principle of the circuit. A 150 W input power CPT system is designed as an example to validate the proposed repeater structure and compensation circuit topology. The system can achieve an efficiency of 66.9% from dc source to dc load, when the transfer distance is 360 mm and the repeater is placed between the transmitter and the receiver. Autors: Hua Zhang;Fei Lu;Heath Hofmann;Weiguo Liu;Chunting Chris Mi; Appeared in: IEEE Transactions on Industry Applications Publication date: Sep 2017, volume: 53, issue:5, pages: 4914 - 4922 Publisher: IEEE
» An Optimization Scheme of Enhanced Adaptive Dynamic Energy Consumption Based on Joint Network-Channel Coding in WSNs
 Abstract:Energy efficiency in wireless sensor networks is a crucial factor that affects the performance of the networks, as long-time and unceasing energy supply is impossible. Recent studies demonstrated that the previously proposed scheme of joint adaptive network-channel coding (JANCC) and adaptive dynamic energy consumption (ADEC) obtained an excellent performance in terms of energy efficiency. Based on the joint network-channel coding, we propose an enhanced ADEC optimization scheme, which integrates the essence of both JANCC and ADEC, and overcomes the shortcomings of them. In the scheme, an identifier vector is inserted into the feedback information. The relay node is able to acquire the specific signs of the channel codes received in error based on the identifier vector and transmit the network coded packets only related to those channel codes received in error. Through this method, it can achieve adjustments for the current round of transmission. Performance analyses and simulation results show that the proposed optimization scheme is more energy efficient than any other schemes of interest under the condition of meeting the requirement of transmission reliability. Autors: Xingcheng Liu;Wei Li;Feng Han;Yi Xie; Appeared in: IEEE Sensors Journal Publication date: Sep 2017, volume: 17, issue:18, pages: 6119 - 6128 Publisher: IEEE
» An RS-GIS-Based ComprehensiveImpact Assessment of Floods—A Case Study in Madeira River, Western Brazilian Amazon
 Abstract:Geographical information systems-based methods can be handled as powerful tools in assessing and quantifying impacts and, thus, supporting strategies for disaster risk reduction (DRR). This is particularly relevant on scenarios of global climate change and intensified increased human interventions on riverine systems. The Madeira River in Porto Velho city (Brazilian Amazon) is a good example of susceptible area to both of these factors. We take advantage of the 2014 flood, the largest recorded for this region, for combining remote sensing and geographic information system with socio, health, and infrastructure data to quantify spatially the flood impacts. Using high resolution airborne images, we applied a machine learning classification algorithm for detecting urban areas. Our results show that at the flood extent related to the highest river level at least 0.65 of urban area, 87 km of urban streets, four public schools, and two public health units were affected. More than 16 800 people suffered the impacts directly, and children represented 29.7% of them. Based on registered data, it was quantified that the city registered more than 20 cases of leptospirosis and the truck flow on the region decreased up to 92%. The spatially-explicit results of this letter are potential to guide strategies aiming to support decision-making for DRR. Autors: Leonardo B. L. Santos;Tiago Carvalho;Liana O. Anderson;Conrado M. Rudorff;Victor Marchezini;Luciana R. Londe;Silvia M. Saito; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Sep 2017, volume: 14, issue:9, pages: 1614 - 1617 Publisher: IEEE
» An SMDP-Based Prioritized Channel Allocation Scheme in Cognitive Enabled Vehicular Ad Hoc Networks
 Abstract:An efficient channel allocation scheme for vehicular networks is required due to the popularization and rapid growth of the corresponding applications in recent years. We propose a channel resource allocation scheme based on a semi-Markov decision policy to provide a solution for the problem of the channel resource shortage in vehicular ad hoc networks (VANETs). In this paper, we consider the channel allocation problem under a cognitive enabled VANET environment. By a semi-Markov decision process (SMDP), the channel allocation decision is made to maximize the overall system rewards. Besides, we consider services from two categories: primary users (PUs) and secondary users. On the top of the overall rewards maximization, we give priority to PU services without blocking any PU requests via cooperation between the roadside units and the base station. Numerical results and evaluations are presented to illustrate the desired performance of the proposed channel allocation scheme. Autors: Mushu Li;Lian Zhao;Hongbin Liang; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Sep 2017, volume: 66, issue:9, pages: 7925 - 7933 Publisher: IEEE
» An Ultra-Low-Power Dual-Polarization Transceiver Front-End for 94-GHz Phased Arrays in 130-nm InP HBT
 Abstract:We present a fully integrated 94-GHz transceiver front-end in a 130-nm/1.1-THz InP HBT process. Low power is obtained through low-voltage design and high transistor gain. The IC is designed for multi-function, dual-polarization phased arrays. At 1.5-V collector bias, in dual-polarization simultaneous receiving mode, the IC has 21-dB gain, <9.3-dB noise figure, and consumes 39 mW, while in transmitting mode with time-duplexed vertical and horizontal outputs, the transceiver front-end achieves 5-dBm output power, 22-dB gain, and consumes 40 mW. At 1-V collector bias, in dual-polarization simultaneous receiving mode, the IC has 22.7-dB gain, <8.9-dB noise figure, and consumes 26 mW, while in transmitting mode, it has 22-dB gain and the saturated output power of 1.4 dBm with 29-mW power consumption. Autors: Seong-Kyun Kim;Robert Maurer;Arda Simsek;Miguel Urteaga;Mark J. W. Rodwell; Appeared in: IEEE Journal of Solid-State Circuits Publication date: Sep 2017, volume: 52, issue:9, pages: 2267 - 2276 Publisher: IEEE
» Analog to Stochastic Bit Stream Converter Utilizing Voltage-Assisted Spin Hall Effect
 Abstract:We introducea spintronic analog to stochastic bit stream (SBS) converter (ASC) based on a three terminal magnetic tunnel junction (MTJ) with a heavymetal layer. The critical current of the spin Hall effect (SHE) for switching the MTJ is efficiently modulated by applying a voltage across the MTJ via the voltage-controlled magnetic anisotropy effect. This effect results in the switching probability linearly depending on the amplitude of the analog input signal of the ASC. There are several advantages of using the voltage-assistedSHE for generating an SBS. The stochastic switching behavior of MTJ devices drastically reduces the area overhead by simplifying control circuits in the ASC. Moreover, the voltage-assisted SHE switching improves energy efficiency over traditional spin transfer torque (STT)-based MTJ switching by diminishing ohmic dissipation. Also, multiple MTJs on a single heavy metal layer increases the bandwidth by simultaneously converting analog input signals to SBSs. The performance of the spintronic ASC was evaluated by using the macrospin three terminal MTJ compactmodel integrated into a 45-nm CMOS technology. The proposed ASC can achieve 7x reduction in power consumption comparedto the previousSTT-basedwork and significant improvement in area-efficiency compared with the pure CMOS-based design. Autors: H. Lee;A. Lee;F. Ebrahimi;P. Khalili Amiri;K. L. Wang; Appeared in: IEEE Electron Device Letters Publication date: Sep 2017, volume: 38, issue:9, pages: 1343 - 1346 Publisher: IEEE
» Analysis and Design of a Thermoelectric Energy Harvesting System With Reconfigurable Array of Thermoelectric Generators for IoT Applications
 Abstract:In this paper, a novel thermoelectric energy harvesting system with a reconfigurable array of thermoelectric generators (TEGs), which requires neither an inductor nor a flying capacitor, is proposed. The proposed architecture can accomplish maximum power point tracking (MPPT) and voltage conversion simultaneously via the reconfiguration of the TEG array, and demonstrate significantly improved power conversion efficiency over the conventional switching converter and switched-capacitor architectures. Two systematical scaling approaches—powers-of-two scaling and maximum-factor scaling—are presented and analyzed to serve as the design guideline, catering for reconfigurable TEG arrays of different sizes. In order to optimize the chip area required, a custom-designed, multi-level hierarchy and systematically scalable switch array that requires a reasonable number of switches is also developed to enable the reconfiguration of the TEG array. The 16-node and 12-node versions of the proposed system have been implemented in a standard 0.35- CMOS process. Measurement results verify the analysis, and confirm that the proposed system can maintain a higher than 88.8% efficiency over a wide range of temperature gradients. Autors: Qiping Wan;Ying-Khai Teh;Yuan Gao;Philip K. T. Mok; Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers Publication date: Sep 2017, volume: 64, issue:9, pages: 2346 - 2358 Publisher: IEEE
» Analysis and Design of Closed-Loop Control of Electrolytic Capacitor-Less Six-Pulse DC Link Three-Phase Inverter
 Abstract:Three-phase inverters in uninterrupted power supply, electric vehicles, and hybrid electric vehicles use an intermediate dc-link electrolytic capacitor, which has reliability issues and is one prominent cause of inverter failure and limited life. The large volume of an electrolytic capacitor increases the size and cost of the system. Recent research on electrolytic capacitorless inverters using six-pulse modulation technique along with high-frequency power conversion has attempted to address this issue. However, closed-loop operation and control has some issues due to capacitorless dc-link. In this paper, closed-loop operation, design, and implementation of an electrolytic capacitorless inverter is presented. A proof-of-concept 1-kW hardware prototype has been built and tested in a laboratory under different loading conditions. In total, 98% rated efficiency of the inverter is obtained with total harmonic distortion within 2%. Transient results during start-up and load change are smooth, demonstrating safe operation of the inverter. Autors: Anirban Ghoshal;Xuewei Pan;Akshay K Rathore; Appeared in: IEEE Transactions on Industry Applications Publication date: Sep 2017, volume: 53, issue:5, pages: 4957 - 4964 Publisher: IEEE
» Analysis and Design of Continuous-Time Delta–Sigma Converters Incorporating Chopping
 Abstract:Chopping the operational transconductance amplifier (OTA) of the input integrator in a CT is a traditional and effective way of addressing flicker noise in such modulators. Unfortunately, chopping leads to aliasing of shaped quantization noise into the signal band and degrades performance. We analyze the mechanisms of shaped-noise aliasing in OTA- integrators that use two-stage feedforward-compensated OTAs, and show that aliasing can be largely mitigated by using an finite impulse response feedback digital-to-analog converter with its zeros placed at multiples of twice the chopping frequency. The theory is borne out by measurement results from a single-bit CT, which achieves a peak SNDR of 98.5 dB in a 24-kHz bandwidth while consuming only 280 from a 1.8-V supply. Realized in a 180-nm CMOS technology, it achieves a noise corner of about 3 Hz when chopped at . Autors: Sujith Billa;Amrith Sukumaran;Shanthi Pavan; Appeared in: IEEE Journal of Solid-State Circuits Publication date: Sep 2017, volume: 52, issue:9, pages: 2350 - 2361 Publisher: IEEE
» Analysis and Design of Improved Weighted Average Current Control Strategy for LCL-Type Grid-Connected Inverters
 Abstract:The LCL grid-connected inverter has the ability to attenuate the high-frequency current harmonics. However, the inherent resonance of the LCL filter affects the system stability significantly. To damp the resonance effect, the dual-loop current control can be used to stabilize the system. The grid current plus capacitor current feedback system is widely used for its better transient response and high robustness against the grid impedance variations. The weighted average current (WAC) feedback scheme is capable to provide a wider bandwidth at higher frequencies but show poor stability characteristics under weak grid scenarios. To overcome this shortcoming, the improved WAC damping method is proposed with an additional capacitor current feedback loop. In this paper, a systematic parameter design guideline for the optimal selection of the current loop proportional resonant controller and the additional capacitor current feedback coefficient are presented for the improved WAC feedback control strategy. The satisfactory range of the system control parameters can be obtained under different delay conditions to meet the system performance specifications. The improved WAC method enhances system robustness under weak grid scenarios, and the stability and robustness have been enhanced under control delay. Finally, the experimental results are presented to validate the effectiveness of the proposed improved WAC control strategy and the parameter design method. Autors: Yang Han;Zipeng Li;Ping Yang;Congling Wang;Lin Xu;Josep M. Guerrero; Appeared in: IEEE Transactions on Energy Conversion Publication date: Sep 2017, volume: 32, issue:3, pages: 941 - 952 Publisher: IEEE
» Analysis of a MEMS Tuned Cavity Oscillator on $X$ -Band
 Abstract:This paper reports on the analysis of a radio frequency microelectromechanical systems (RF-MEMS) tuned cavity oscillator on -band based on a GaN-HEMT monolithic microwave integrated circuit reflection amplifier. The RF-MEMS-switches are mounted on a low-loss printed circuit board (PCB) intruded in an aluminum cavity that is coupled to a microstrip line connected to the reflection amplifier. This paper investigates the influence of the number of switches as well as their positions with respect to phase noise and tuning range. Vertical and horizontal positions of the switches are varied with target on optimum trade-off between phase noise and total tuning range. For a three-row MEMS-configuration at 1-mm depth from the end cavity wall, a tuning range of 4.9% is measured. The center frequencies are ranging from 9.84 to 10.33 GHz with measured phase noise of −140 to −129 dBc/Hz at 100-kHz offset. A similar three-row MEMS setup at 2.5-mm depth provides a tuning range of 12.3% with measured phase noise of −133 to −123 dBc/Hz at 100-kHz offset. Autors: Mikael Hörberg;Thomas Emanuelsson;Herbert Zirath;Dan Kuylenstierna; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Sep 2017, volume: 65, issue:9, pages: 3257 - 3268 Publisher: IEEE
» Analysis of a Novel Metal Implant Junctionless Tunnel FET for Better DC and Analog/RF Electrostatic Parameters
 Abstract:Steep rise in the subthreshold slope, high current driving capability, and negligible ambipolarity are the major prerequisite conditions of tunnel FETs (TFETs) to make it applicable for Analog/RF circuit applications. Along with that, fabrication of physically doped TFETs is a major concern in device technology. In this context, this paper deals with junctionless TFET with a metal implanted in the oxide at the source/channel and drain/channel junctions to enhance its ON-current and reduce the ambipolar nature. The metal introduced at the source/channel junction generates abruptness and brings improvement in subthreshold slope, which increases the current driving capability of the device. Similarly, the metal implanted at the drain/channel junction widens the energy gap at the same junction to reduce the ambipolar behavior of the device. This also contributes to the enhancement of dc and analog/RF performance of the device. The selection of appropriate work function and length of the metal implanted at both the interfaces is important to maintain the improved ON-current and ambipolarity. This optimization gives idea of keeping the appropriate length, which provides direction toward practical feasibility at the experimental level. Autors: Sukeshni Tirkey;Dheeraj Sharma;Dharmendra Singh Yadav;Shivendra Yadav; Appeared in: IEEE Transactions on Electron Devices Publication date: Sep 2017, volume: 64, issue:9, pages: 3943 - 3950 Publisher: IEEE
» Analysis of a Novel Stator Construction Employing Steel Wire in Place of Laminations
 Abstract:This paper examines a novel method of constructing large diameter generators using many layers of steel wire in place of laminations. The stator coreback is formed by winding thin steel wire around the outside of the armature coils and then encapsulating the structure in epoxy. This technique simplifies the manufacturing process by removing the requirement to build a large support structure to carry the laminations. The electromagnetic behavior of a wire coreback is very different from traditional laminations, however, and produces abrupt changes in flux density across its thickness. The material is difficult to model using conventional FEA techniques due to the large number of elements required to mesh the small diameter wire. This paper examines two alternative modeling approaches. Method 1 uses two-dimensional (2-D) FEA to model the steel wire as a lamination oriented in the “wrong” direction. Method 2 uses a quasi-analytic approach based on detailed 3-D FE analysis of a small section of the generator to capture the flux density profile in the airgap. The two models are benchmarked against a prototype generator tested in the laboratory, and it is shown that the quasi-analytical technique gives the most accurate prediction of performance. Autors: Nick Stannard;Richard Martin;Glynn J. Atkinson; Appeared in: IEEE Transactions on Energy Conversion Publication date: Sep 2017, volume: 32, issue:3, pages: 993 - 1001 Publisher: IEEE
» Analysis of Atomistic Dopant Variation and Fermi Level Depinning in Nanoscale Contacts
 Abstract:Using quantum transport simulations of metal–semiconductor junctions, we assess the viability of barrier thinning with dopants and barrier lowering with interfacial layers as solutions for contact resistivity in nanoscale transistors. Our atomistic simulations show that the discreteness of dopants leads to increasing variability in contact resistance as dimensions scale below 10 nm. We find that the use of interlayers can counteract low doping caused by atomistic variation, but the interlayer must have band edge Fermi level pinning to provide a net reduction in contact resistivity. For materials with low doping limits, such as n-type germanium, we find that interlayer contacts still have difficulty meeting resistivity targets. Autors: Gautam Shine;Krishna C. Saraswat; Appeared in: IEEE Transactions on Electron Devices Publication date: Sep 2017, volume: 64, issue:9, pages: 3768 - 3774 Publisher: IEEE
» Analysis of Correlated MRC With Transmit Antenna Selection Under $\eta$–$\mu$ Fading
 Abstract:A wireless link considering correlated maximal ratio combining and transmit antenna selection under the general – fading is analyzed. Exact and asymptotic expressions for the cumulative distributing function (CDF) and probability density function (PDF) are derived. These new results are used to evaluate the outage capacity and the asymptotic average bit error rate for different binary modulations. The obtained theoretical results are validated through Monte Carlo simulations. Autors: Concepción Téllez-Labao;Juan P. Peña-Martín;Juan M. Romero-Jerez; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Sep 2017, volume: 66, issue:9, pages: 8580 - 8584 Publisher: IEEE
» Analysis of Fundamental-Mode Beam Transport in Highly Multimode Fibers
 Abstract:In view of the growing demand for fiber beam delivery in manufacturing systems with close to diffraction-limited beam quality, we present an analysis of the propagation of a nearly diffraction-limited laser beam through 5 to 10 m long multimode step-index fibers with a numerical aperture of 0.111 and core diameters of up to 80 μm. The influence of the launching conditions are investigated theoretically and experimentally by varying the beam size of the input beam. At a core diameter as high as 80 μm, corresponding to a mode field area of 2800 μm2, and an optimum launching condition, the transmitted M2 was measured to be around 1.3. It is shown that bending of the fibers down to radii as small as 2 cm barely influences the beam quality factor of the transmitted beam for all the tested fibers as the M2 was always found to be smaller than 1.5. The threshold of stimulated Raman scattering was measured to be around 60 kW for a fiber loosely placed on the table (rbend ≥ 25 cm) with a total length of 10 m and a core diameter of 80 μm. Autors: Christian Röhrer;Götz Kleem;Marwan Abdou Ahmed;Thomas Graf; Appeared in: Journal of Lightwave Technology Publication date: Sep 2017, volume: 35, issue:17, pages: 3637 - 3642 Publisher: IEEE
 Abstract:A methodology is presented to analyze the impact of the termination load on the oscillation frequency and output power of autonomous circuits. Variations of this load can also lead to an extinction of the oscillation signal, due to their effect on the impedance seen by the active device(s). The new methodology enables an efficient analysis and mitigation of the pulling effects, in the case of undesired output mismatch, as well as an efficient oscillator synthesis in large-signal conditions, for specified values of oscillation frequency and output power. The method is based on the calculation of constant-amplitude and constant-frequency contours, traced in the Smith chart. Oscillation extinctions and some forms of hysteresis can be predicted through the inspection of these contours. However, the stability properties will generally depend on the frequency characteristic of the termination impedance. In an oscillator synthesis, the selected impedance, providing the specified values of oscillation frequency and output power, must be implemented in order to guarantee a stable solution. The dependence of the phase-noise spectral density on the particular implementation is predicted, combining an analysis based on the variance of the phase deviation with the conversion-matrix approach. Autors: Almudena Suárez;Mabel Pontón;Sergio Sancho;Franco Ramírez; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Sep 2017, volume: 65, issue:9, pages: 3135 - 3146 Publisher: IEEE
» Analysis of PM Transverse-Flux Outer Rotor Machines With Different Configuration
 Abstract:This paper presents the electromagnetic analysis of two permanent magnet transverse-flux outer rotor machines with and without magnetic shunts. The research started with designing and analyzing a permanent magnet transverse-flux machine with an inner rotor, previously patented by J. Giearas in 2010. However, the results obtained from the prototype test differed significantly from the estimated results. Applying three-dimensional (3-D) finite element method (FEM), the main problem of the machine was detected. The problem was in high flux leakage that weakened magnetic flux density in the stator poles. Such observation led to designing two machines with outer rotor, with and without magnetic shunts. The role of the magnetic shunts is to minimize flux leakage in the stator in order to improve the performance of the machine. Electromechanical parameters of both outer rotor machines, with and without magnetic shunts, are compared in the paper. Three-D FEM results are supported by laboratory analysis of the machines’ prototypes. Experimental measurements proved that the machine with magnetic shunts demonstrated better performance as compared with the machine without magnetic shunts. Presence of the magnetic shunts in the machine resulted in reducing of flux leakage and cogging torque. Autors: Oleksandr Dobzhanskyi;Rupert Gouws;Ebrahim Amiri; Appeared in: IEEE Transactions on Industry Applications Publication date: Sep 2017, volume: 53, issue:5, pages: 4260 - 4268 Publisher: IEEE
» Analysis of Saturated Belief Propagation Decoding of Low-Density Parity-Check Codes
 Abstract:We consider the effect of log-likelihood ratio saturation on the belief-propagation decoding of low-density parity-check codes. Saturation is commonly done in practice and is known to have a significant effect on the error-floor performance. Our focus is on threshold analysis and the stability of density evolution. We analyze the decoder for standard low-density parity-check code ensembles and show that belief-propagation decoding generally degrades gracefully with saturation. Stability of density evolution is, on the other hand, rather strongly affected by saturation, and the asymptotic qualitative effect of saturation is similar to reduction by one of variable-node degree. We also describe conditions under which the block-error threshold for saturated belief-propagation decoding equals the bit-error threshold. Autors: Shrinivas Kudekar;Tom Richardson;Aravind R. Iyengar; Appeared in: IEEE Transactions on Information Theory Publication date: Sep 2017, volume: 63, issue:9, pages: 5734 - 5751 Publisher: IEEE
» Analysis of Temperature Effects on Performance of Interior Permanent Magnet Machines for High Variable Temperature Applications
 Abstract:The purpose of this paper is to analyze and investigate the influence of temperature variation on the characteristics and performance of interior permanent magnet (IPM) machines. The impact of temperature variation on the materials of IPM machines is discussed to show the sources of performance variation. The flux linkages, torque output capability, and inductance variation as functions of the temperature are analyzed and discussed. This paper also shows the influence of temperature variation on key IPM machines performance including constant torque curves, voltage limit ellipses, maximum torque per ampere trajectories, and torque–speed curves. Experimental results of a traction IPM machine verified the analysis and theory. The results and trends shown in this paper set a foundation for developing control algorithm, which takes the temperature effects into consideration, especially in the applications where operating temperature varies significantly. Autors: Silong Li;Bulent Sarlioglu;Sinisa Jurkovic;Nitin R. Patel;Peter Savagian; Appeared in: IEEE Transactions on Industry Applications Publication date: Sep 2017, volume: 53, issue:5, pages: 4923 - 4933 Publisher: IEEE
» Analysis of the Impact of Microgrid Penetration on Power System Dynamics
 Abstract:The paper proposes a stochastic model to analyse the dynamic coupling of the transmission system, the electricity market, and microgrids. The focus is on the impact of microgrids on the transient response of the system and, in particular, on frequency variations. Extensive Monte Carlo simulations are performed on the IEEE 39-bus system, and show that the dynamic response of the transmission system is affected in a nontrivial way by both the number and the size of the microgrids. Autors: Pietro Ferraro;Emanuele Crisostomi;Marco Raugi;Federico Milano; Appeared in: IEEE Transactions on Power Systems Publication date: Sep 2017, volume: 32, issue:5, pages: 4101 - 4109 Publisher: IEEE
» Analysis of the Magnetostatic Energy of Chains of Single-Domain Nanomagnets for Logic Gates
 Abstract:Nanomagnet logic (NML) circuits are magnetic field-coupled interacting structures built up from nanoscaled magnets to perform logic operations. The bistable character of nanomagnets’ magnetization is associated with “0” and “1” logic states, which may be used to perform Boolean operations. In this paper, we first investigate the limits of single-domain magnetic structure in modeling the magnetostatic energy of particles of several polyhedron shapes. The model, which is based on the evaluation of multidimensional integrals through the Monte Carlo method, includes the demagnetizing energy of individual magnetic specimens and the dipolar coupling between two or more nanomagnets. The accuracy and the limits of the model are evaluated through comparison with a well-established numerical micromagnetic solver. The magnetostatic behavior for several configurations of horizontal chain of interacting nanomagnets (NML wire) is investigated. Rectangular nanomagnets present weak dipolar antiferromagnetic (AF) coupling that may result in error during information propagation across the chain. We examine a novel wire structure formed by a sequence of different slanted nanomagnets that yield strong dipolar coupling. For this system, error during information propagation is very unlikely, since the magnetic energy of the particles has single global minima corresponding to stable AF alignment. The proposed model can be readily applied as a tool for the study of advanced NML circuits and systems. Autors: Luiz G. C. Melo;Thiago R. B. S. Soares;Omar P. Vilela Neto; Appeared in: IEEE Transactions on Magnetics Publication date: Sep 2017, volume: 53, issue:9, pages: 1 - 10 Publisher: IEEE
» Analysis of the Performance Enhancement of MIMO Systems Employing Circular Polarization
 Abstract:The advantages of adopting circular polarization in multiple-input-multiple-output (MIMO) systems are illustrated for both line-of-sight (LOS) and multipath propagation. More in detail, an analysis of the MIMO performance attainable by employing orthogonal circularly polarized (CP) radiators with respect to orthogonal linearly polarized (LP) ones, has been addressed. At first, an accurate analysis is presented aimed at the evaluation of the channel matrix by comprehensively including also the effects of the antenna in LOS condition. In particular, the channel matrix has been calculated as a function of the antenna parameters and orientation, demonstrating that CP radiators are capable of obtaining better average values of the matrix eigenvalues with respect to LP ones. The analysis is therefore completed by evaluating the characteristics of a CP MIMO system operating in indoor environment representing this latter a more challenging condition where multipath propagation occurs. In this latter case, some meaningful numerical experiments have been performed by using a reliable ray-tracing solver, followed by a measurements campaign conducted in a real environment for validation purposes. Measurements, which are in good agreement with simulations, confirm the benefits of adopting circular polarization in MIMO systems with respect to LP. Autors: Francesco Alessio Dicandia;Simone Genovesi;Agostino Monorchio; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Sep 2017, volume: 65, issue:9, pages: 4824 - 4835 Publisher: IEEE
» Analysis of Time-Series Spectral Index Data to Enhance Crop Identification Over a Mediterranean Rural Landscape
 Abstract:Spectral index time series can provide valuable phenological information into the classification process for the precise crop mapping, in order to reduce misclassification rates associated with low interclass and high intraclass spectral variability. Stochastic hidden Markov models (HMMs) are efficient yet computationally demanding classification approach which can simulate crop dynamics, exploiting the spectral information of their phenological states and the relations between these states. This letter aims to present a methodology which achieves accurate classification results while maintaining a low computational cost. A classification framework based on HMMs was developed, and different spectral indices were generated from the time series of Landsat ETM+ and RapidEye imagery, for modeling crop vegetation dynamics over a Mediterranean rural area, with high spatiotemporal crop heterogeneity. To further improve the HMMs indices classification, separability analysis and two different decision fusion strategies were tested. The assessment of the classification accuracy, along with an evaluation of the computational cost, indicated that the green-red vegetation index produced the most favorable results among the individual spectral indices. Although the decision fusion based on an integration of a reliability factor increased the overall accuracy by 3.1%, this came at the cost of computational time, compared to the separability analysis model which required less processing time. Autors: Sofia Siachalou;Giorgos Mallinis;Maria Tsakiri-Strati; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Sep 2017, volume: 14, issue:9, pages: 1508 - 1512 Publisher: IEEE
» Analysis of Wideband Circularly Polarized Ferrite-Loaded Antenna Based on Unidirectional Resonant Modes
 Abstract:We propose a wideband circularly polarized antenna that consists of a metallic patch and some parasitically coupled elements mounted on a grounded dielectric-ferrite substrate. The metallic patch is fed by a proximity-coupled feed line placed between the ferrite and the dielectric layers. The parasitically coupled elements are included to improve the impedance bandwidth of antenna and are excited through the metallic patch. The antenna utilizes the resonant modes of the structure, which rotate only in the clockwise or counter-clockwise direction. A semi-analytical solution based on the magnetic wall approximation shows that the resonance frequencies of the clock- and counter-clockwise resonant modes differ significantly when operating in the frequency range where the effective permeability of the ferrite layer is negative. Moreover, there is a good agreement between the model presented and full-wave numerical simulations. For the proposed antenna, the results show that the radiation bandwidth is more than 15.5% and the 3 dB axial ratio bandwidth is more than 50%. The proposed antenna is easy to design and fabricate, does not require a complicated feeding network, and has a wideband and wide-angle circular polarization. Autors: M. Mashhadi;B. Rejaei;N. Komjani;J. Ghalibafan; Appeared in: IEEE Transactions on Magnetics Publication date: Sep 2017, volume: 53, issue:9, pages: 1 - 8 Publisher: IEEE
» Analysis on Ensemble of Regenerating Codes and Replication
 Abstract:This letter studies the performance of ensemble of Regenerating codes and Replication (RR). It theoretically analyzes the storage-bandwidth tradeoff curve of RR, and attains two extremal cases, corresponding to minimum storage cost RR (MSRR) and minimum repair bandwidth RR (MBRR), respectively. Compared with the case of independently applying regenerating codes, the evaluation results indicate, with extra storage cost, MSRR has better average repair bandwidth and average disk I/O, and MBRR has less average disk I/O cost and almost the same level of average repair bandwidth, i.e., when satisfying the data available probability , MSRR achieves at least 5.6% and 50%, and MBRR achieves at least 23.7% and 1.3% less disk I/O and repair bandwidth consumption in evaluation data sets, respectively. Autors: Zimu Yuan;Huiying Liu; Appeared in: IEEE Communications Letters Publication date: Sep 2017, volume: 21, issue:9, pages: 1901 - 1904 Publisher: IEEE
» Analytical Calculation and Optimization of Magnetic Field in Spoke-Type Permanent-Magnet Machines Accounting for Eccentric Pole-Arc Shape
 Abstract:This paper presents an analytical method for calculating and optimizing magnetic field in spoke-type permanent-magnet machines accounting for eccentric pole-arc shape. Normalized flux density is derived from conformal transformation taking into account eccentric pole-arc shape, and final field solution is predicted according to the flux continuity theorem. The optimal results show the harmonic content of flux density can be reduced a lot by optimizing eccentric distance of eccentric pole arc while fundamental content will reduce a little. The proposed analytical solution on prototype machines is implemented. The finite element (FE) and experimental results confirm that the developed analytical method has high accuracy for predicting and optimizing magnetic field. Autors: Yu Zhou;Huaishu Li;Ningning Ren;Zhiqiang Xue;Yingsan Wei; Appeared in: IEEE Transactions on Magnetics Publication date: Sep 2017, volume: 53, issue:9, pages: 1 - 7 Publisher: IEEE
» Analytical Drain Current Model for Amorphous InGaZnO Thin-Film Transistors at Different Temperatures Considering Both Deep and Tail Trap States
 Abstract:Surface-potential-based drain current model is presented for amorphous InGaZnO thin-film transistors considering both exponential deep and tail trap states densities in the energy gap. The trap states densities are determined by the numerical calculation on the basis of the assumption that the trapped carrier concentration is much higher than the free carrier concentration. The analytical drain current model is developed consistent with the numerical calculation, and verified by the experimental data at different temperatures. Autors: Hongyu He;Yuan Liu;Binghui Yan;Xinnan Lin;Xueren Zheng;Shengdong Zhang; Appeared in: IEEE Transactions on Electron Devices Publication date: Sep 2017, volume: 64, issue:9, pages: 3654 - 3660 Publisher: IEEE
» Analytical Drain Current Model of 1-D Ballistic Schottky-Barrier Transistors
 Abstract:A new analytical model based on the Wentzel–Kramers–Brillouin approximation for MOSFET-like 1-D ballistic transistors with Schottky-Barrier contacts has been developed for the drain current. By using a proper approximation of both the Fermi–Dirac distribution function and transmission probability, an analytical solution for the Landauer integral was obtained, which overcomes the limitations of existing models and extends their applicability toward high bias voltages needed for analog applications. The simulations of transfer and output characteristics are found to be in agreement with the experimental data for sub-10-nm carbon-nanotube FETs. Autors: Igor Bejenari;Michael Schröter;Martin Claus; Appeared in: IEEE Transactions on Electron Devices Publication date: Sep 2017, volume: 64, issue:9, pages: 3904 - 3911 Publisher: IEEE
» Analytical Formulas for the Coverage of Tunable Matching Networks for Reconfigurable Applications
 Abstract:Tunable matching networks (MNs) are essential components for agile radio frequency systems. To optimally design such networks, the total area they cover on the Smith chart needs to be determined. In this paper, the coverage areas of typical MNs have been determined analytically for the first time. It has been found that the coverage area is encompassed by up to five arcs. Analytical expressions for the centers and radii for these arcs have been derived. The theoretical analysis is provided for four typical MNs and verified by circuit simulation and measured data. Moreover, a dynamically load-modulated power amplifier has been designed using the presented theoretical techniques, which demonstrates a measured improvement in the power added efficiency of up to 5% in the frequency range of (0.8–0.9) GHz. Autors: Eyad Arabi;Kevin A. Morris;Mark A. Beach; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Sep 2017, volume: 65, issue:9, pages: 3211 - 3220 Publisher: IEEE
» Analytical Formulas for Underwater and Aerial Object Localization by Gravitational Field and Gravitational Gradient Tensor
 Abstract:Object localization techniques have significant applications in civil fields and safety problems. A novel analytical formula is developed for accurate underwater and aerial object real-time localization by combining gravitational field and horizontal gravitational gradient anomalies. The proposed method enhances the accuracy of object localization and its excess mass estimation; it also effectively avoids the possible numerical instability and the singularity in the previous works. Finally, a synthetic underwater object navigation model was adopted to verify its performance. The results show that our newly developed method is more practical than existing methods. Autors: Jingtian Tang;Shuanggui Hu;Zhengyong Ren;Chaojian Chen;Xiao Xiao;Cong Zhou; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Sep 2017, volume: 14, issue:9, pages: 1557 - 1560 Publisher: IEEE
» Analytical Model for 2DEG Density in Graded MgZnO/ZnO Heterostructures With Cap Layer
 Abstract:In this paper, we develop a generic analytical model for 2-D electron gas (2DEG) density ( and threshold voltage ( of a fully strained graded ZnO-based heterostructure with a cap layer. The model is based on the continuity of electric field at the interfaces of different layers, dominant piezoelectric and spontaneous polarization components in different layers, Mg composition, and layer thickness. The generic model can be reduced to a simplified bilayer structure for calculating and . Results show that the graded heterostructure can result in higher values of 2DEG density and (absolute values) compared to the bilayer structure. A careful optimization of the structure is required to achieve a trade-off between and . An analytical expression of polarization charge density at buffer–barrier interface to better fit the experimental data available in the literature is also proposed. The model will be suitable for the design optimization of 2DEG density and for ZnO-based heterostructures. Autors: Rohit Singh;Md Arif Khan;Shaibal Mukherjee;Abhinav Kranti; Appeared in: IEEE Transactions on Electron Devices Publication date: Sep 2017, volume: 64, issue:9, pages: 3661 - 3667 Publisher: IEEE
» Analytical Model for Combined Study of Magnet Demagnetization and Eccentricity Defects in Axial Flux Permanent Magnet Synchronous Machines
 Abstract:A time-harmonic analytical model is presented for a combined study of demagnetization and rotor eccentricity in single-stator double-rotor axial flux permanent magnet synchronous machines (AFPMSM). Demagnetization defects are modeled by scaling the magnetization “square wave” by magnetization factors for each individual magnet on both rotors. Static, dynamic, and mixed rotor eccentricities are modeled using a permeance function. The original contribution of the model is that asymmetrical defects in the two air gaps of the machine can be described with acceptable accuracy and limited additional calculation time. The model is validated with a finite element method and experiments in both healthy and defected operations. Because the model has a short computation time, it is useful for real-time condition monitoring of any AFPMSM with double air gap and either concentrated or distributed windings. Autors: Jan De Bisschop;Peter Sergeant;Ahmed Hemeida;Hendrik Vansompel;Luc Dupré; Appeared in: IEEE Transactions on Magnetics Publication date: Sep 2017, volume: 53, issue:9, pages: 1 - 12 Publisher: IEEE
» Analytical Model for SDN Signaling Traffic and Flow Table Occupancy and Its Application for Various Types of Traffic
 Abstract:Software defined networking (SDN) has emerged as a promising networking paradigm overcoming various drawbacks of current communication networks.The control and data plane of switching devices is decoupled and control functions are centralized at the network controller. In SDN, each new flow introduces additional signaling traffic between the switch and the controller. Based on this traffic, rules are created in the flow table of the switch, which specify the forwarding behavior. To avoid table overflows, unused entries are removed after a predefined time-out period. Given a specific traffic mix, the choice of this time-out period affects the tradeoff between signaling rate and table occupancy. As a result, network operators have to adjust this parameter to enable a smooth and efficient network operation. Due to the complexity of this problem caused by the various traffic flows in a network, a suitable abstraction is necessary in order to derive valid parameter values in time. The contribution of this paper is threefold. First, we formulate a simple analytical model that allows optimizing the network performance with respect to the table occupancy and the signaling rate. Second, we validate the model by means of simulation. Third, we illustrate the impact of the time-out period on the signaling traffic and the flow table occupancy for different data-plane traffic mixes and characteristics. This includes scenarios with single application instances, as well as multiple application instances of different application types in an SDN-enabled network. Autors: Christopher Metter;Michael Seufert;Florian Wamser;Thomas Zinner;Phuoc Tran-Gia; Appeared in: IEEE Transactions on Network and Service Management Publication date: Sep 2017, volume: 14, issue:3, pages: 603 - 615 Publisher: IEEE
» Analytical Modeling of Mutually Coupled Switched Reluctance Machines Under Saturation Based on Design Geometry
 Abstract:An analytical calculation of the winding flux linkages and torque is proposed for fully pitched mutual coupled switched reluctance motors to develop a machine model without using numerical methods. The proposed technique is not empirical and does not require any finite-element analysis (FEA). The design parameters and the material properties of the machine are the only inputs to the model, which can predict the winding flux linkages and torque at any phase currents and rotor positions. The model is applicable for the rotor positions where the stator and rotor poles overlap. Initial assumptions and then the step-by-step procedure for flux linkage, co-energy, and torque calculations are provided. The flux linkages and torque predicted through the proposed modeling technique are compared with the FEA results. Finally, experimental results of flux linkage and torque are provided to verify the accuracy of the proposed modeling technique. Autors: Wasi Uddin;Yilmaz Sozer; Appeared in: IEEE Transactions on Industry Applications Publication date: Sep 2017, volume: 53, issue:5, pages: 4431 - 4440 Publisher: IEEE
» Analytical Unit Cell Assembly for Efficient Chip/Package Power Distribution Network Modeling
 Abstract:Equivalent-circuit models for efficiently simulating 2-D power distribution networks (PDNs) in packages and chips are usually based on a star-type network, where all the branch networks have one port at the star center. This letter presents a simple analytical method for constructing the start network without relying on circuit simulators. The method is based only on the admittance matrix manipulation of each branch network. The star network assembly method is general since it has no limitation on the number of star branches. The method is applied to a specific PDN example and it is validated by means of a commercial circuit simulator as well as full-wave and measured data. Autors: F. de Paulis;S. Piersanti;A. Orlandi; Appeared in: IEEE Microwave and Wireless Components Letters Publication date: Sep 2017, volume: 27, issue:9, pages: 815 - 817 Publisher: IEEE
» Analyzing and Enhancing Dynamic Threshold Policy of Data Center Switches
 Abstract:Today’s data center switches usually employ on-chip shared memory; buffer management policy in them is essential to ensure fair sharing of memory among all ports. Among various polices, Dynamic Threshold  (DT) policy is widely used by switch vendors. Meanwhile, in data centers, distributed applications such as MapReduce often introduce micro-burst traffic into network and the packet dropping caused by micro-burst usually leads to serious performance degradation. When micro-burst traffic arrives at switches, DT is unable to fully utilize the buffer to absorb it. Therefore, in this paper, we theoretically deduce the sufficient conditions for packet dropping caused by micro-burst traffic, and quantitatively estimate the free buffer size when packets are dropped. The results show that the free buffer size can be very large when the number of overloaded ports is small. What’s worse, to ensure fair sharing of memory among output ports, packets from micro-burst traffic may be dropped even when the traffic size is much smaller than the buffer size. In light of these results, we propose the Enhanced Dynamic Threshold (EDT) policy, which can alleviate packet dropping caused by micro-burst traffic through fully utilizing the switch buffer and temporarily relaxing the fairness constraint. The simulation results show that EDT can absorb more micro-burst traffic than DT. Autors: Danfeng Shan;Wanchun Jiang;Fengyuan Ren; Appeared in: IEEE Transactions on Parallel and Distributed Systems Publication date: Sep 2017, volume: 28, issue:9, pages: 2454 - 2470 Publisher: IEEE
» Analyzing the Performance of Spectrum Sensing in Cognitive Radio Systems With Dynamic PU Activity
 Abstract:In this letter, we study the performance of the energy detector for opportunistic spectrum access (OSA) by a secondary user (SU) in dynamic scenarios, where a primary user (PU) switches from active to inactive at random time instances. Specifically, we model the PU activity using a two-state Markov chain and derive analytical expressions for the probabilities of detection and false alarm that explicitly consider the changes in the PU signal that may occur during the sensing interval by the SU. The expressions obtained are corroborated with numerical results obtained from simulations. Autors: Sara MacDonald;Dimitrie C. Popescu;Otilia Popescu; Appeared in: IEEE Communications Letters Publication date: Sep 2017, volume: 21, issue:9, pages: 2037 - 2040 Publisher: IEEE
» Angle Domain Signal Processing-Aided Channel Estimation for Indoor 60-GHz TDD/FDD Massive MIMO Systems
 Abstract:This paper proposes a practical channel estimation for 60-GHz indoor systems with the massive uniform rectangular array at base station. Through antenna array theory, the parameters of each channel path can be decomposed into the angular information and the channel gain information. We first prove that the true direction of arrivals of each uplink path can be extracted via an efficient array signal processing method. Then, the channel gain information could be obtained linearly with small amount of training resources, which significantly reduces the training overhead and the feedback cost. More importantly, the proposed scheme unifies the uplink/downlink channel estimations for both the time duplex division and frequency duplex division systems, making itself particularly suitable for protocol design. Compared with the existing channel estimation algorithms, the newly proposed one does not require any knowledge of channel statistics and can be efficiently deployed by the 2-D fast Fourier transform. Meanwhile, the number of user terminals simultaneously served can be increased from a sophisticatedly designed angle division multiple access scheme. Simulation results are provided to corroborate the proposed studies. Autors: Dian Fan;Feifei Gao;Gongpu Wang;Zhangdui Zhong;Arumugam Nallanathan; Appeared in: IEEE Journal on Selected Areas in Communications Publication date: Sep 2017, volume: 35, issue:9, pages: 1948 - 1961 Publisher: IEEE
» Ankle Joint Intrinsic Dynamics is More Complex than a Mass-Spring-Damper Model
 Abstract:This paper describes a new small signal parametric model of ankle joint intrinsic mechanics in normal subjects. We found that intrinsic ankle mechanics is a third-order system and the second-order mass-spring-damper model, referred to as IBK, used by many researchers in the literature cannot adequately represent ankle dynamics at all frequencies in a number of important tasks. This was demonstrated using experimental data from five healthy subjects with no voluntary muscle contraction and at seven ankle positions covering the range of motion. We showed that the difference between the new third-order model and the conventional IBK model increased from dorsi to plantarflexed position. The new model was obtained using a multi-step identification procedure applied to experimental input/output data of the ankle joint. The procedure first identifies a non-parametric model of intrinsic joint stiffness where ankle position is the input and torque is the output. Then, in several steps, the model is converted into a continuous-time transfer function of ankle compliance, which is the inverse of stiffness. Finally, we showed that the third-order model is indeed structurally consistent with agonist–antagonist musculoskeletal structure of human ankle, which is not the case for the IBK model. Autors: Ehsan Sobhani Tehrani;Kian Jalaleddini;Robert E. Kearney; Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering Publication date: Sep 2017, volume: 25, issue:9, pages: 1568 - 1580 Publisher: IEEE
» Application of Dual-Polarimetry SAR Images in Multitemporal InSAR Processing
 Abstract:Multitemporal polarimetric synthetic aperture radar (SAR) data can be used to estimate the dominant scattering mechanism of targets in a stack of SAR data and to improve the performance of SAR interferometric methods for deformation studies. In this letter, we developed a polarimetric form of amplitude difference dispersion (ADD) criterion for time-series analysis of pixels in which interferometric noise shows negligible decorrelation in time and space in small baseline algorithm. The polarimetric form of ADD is then optimized in order to find the optimum scattering mechanism of the pixels, which in turn is used to produce new interferograms with better quality than single-pol SAR interferograms. The selected candidates are then combined with temporal coherency criterion for final phase stability analysis in full-resolution interferograms. Our experimental results derived from a data set of 17 dual polarizations X-band SAR images (HH/VV) acquired by TerraSAR-X shows that using optimum scattering mechanism in the small baseline method improves the number of pixel candidates for deformation analysis by about 2.5 times in comparison with the results obtained from single-channel SAR data. The number of final pixels increases by about 1.5 times in comparison with HH and VV in small baseline analysis. Comparison between persistent scatterer (PS) and small baseline methods shows that with regards to the number of pixels with optimum scattering mechanism, the small baseline algorithm detects 10% more pixels than PS in agricultural regions. In urban regions, however, the PS method identifies nearly 8% more coherent pixels than small baseline approach. Autors: Mostafa Esmaeili;Mahdi Motagh;Andy Hooper; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Sep 2017, volume: 14, issue:9, pages: 1489 - 1493 Publisher: IEEE
» Application of GCOM-W AMSR2 and S-NPP ATMS Hydrological Products to a Flooding Event in the United States
 Abstract:Satellite remotely sensed products provide critical information to weather forecasters at the National Oceanic and Atmospheric Administration (NOAA) and greatly supplement spare or nonexistent surface observations. Low earth orbiting passive microwave sensors provide unique information related to atmospheric moisture and precipitation, as well as surface properties such as oceanic wind speed. This paper will focus on two microwave sensors that are part of NOAA's Joint Polar Satellite System—the Advanced Microwave Scanning Radiometer 2 (AMSR2) and the Advanced Technology Microwave Sounder (ATMS)—which are flown on Japan's Global Change Observation Mission—Water (GCOM-W1) and the Suomi National Polar orbiting Partnership (S-NPP) satellites. The orbits of GCOM-W1 and S-NPP are such that AMSR2 and ATMS observe the same region of the earth nearly the same time of the day. This allows for comparison of similar products from the two sensors, which is of great interest to users such as NOAA's National Weather Service. In this paper, we focus on product comparisons for a historic flooding event in the U.S. associated with Hurricane Joaquin. The microwave products are presented and shown with other widely used in-situ observations. The performance of AMSR2 and ATMS products are compared. The higher spatial resolution of the AMSR2 sensor provides more detailed information on water vapor and rain rate compared to ATMS. On the other hand, the wider swath width of the ATMS provides a more continuous field of water vapor and precipitation, as well as water vapor retrievals over land. Autors: Ralph Ferraro;Patrick Meyers;Paul Chang;Zorana Jelenak;Christopher Grassotti;Shuyan Liu; Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Publication date: Sep 2017, volume: 10, issue:9, pages: 3884 - 3891 Publisher: IEEE
» Application of Microgrids in Supporting Distribution Grid Flexibility
 Abstract:Distributed renewable energy resources have attracted significant attention in recent years due to the falling cost of the renewable energy technology, extensive federal and state incentives, and the application in improving load-point reliability. This growing proliferation, however, is changing the traditional consumption load curves by adding considerable levels of variability and further challenging the electricity supply–demand balance. In this paper, the application of microgrids in effectively capturing the distribution network net load variability, caused primarily by the prosumers, is investigated. Microgrids provide a viable and localized solution to this challenge, while removing the need for costly investments by the electric utility on reinforcing the existing electricity infrastructure. A flexibility-oriented microgrid optimal scheduling model is proposed and developed to coordinate the microgrid net load with the aggregated consumers/prosumers net load in the distribution network with a focus on ramping issues. The proposed coordination is performed to capture both inter- and intra-hour net load variabilities. Numerical simulations on a test distribution feeder with one microgrid and several consumers and prosumers exhibit the effectiveness of the proposed model. Autors: Alireza Majzoobi;Amin Khodaei; Appeared in: IEEE Transactions on Power Systems Publication date: Sep 2017, volume: 32, issue:5, pages: 3660 - 3669 Publisher: IEEE
» Application of Shifted Frequency Internal Equivalence to Multifrequency Scattering Problems
 Abstract:In this paper, a simple solution is presented for multifrequency electromagnetic scattering from inhomogeneous bodies. Shifted frequency internal equivalence is used to replace the electromagnetic problem at operating frequency by equivalent volume and current sources at internal frequency , and hence repeated calculation of system matrix as in the solution of volume integral equation at multiple frequencies is avoided. The volume field equation and surface tangent field equations obtained from the internal and external problems, the substitutes of the original scattering problem internally and externally, are solved by method of moments with pulse function expansion and point matching. Numerical results demonstrate that the proposed method is accurate and efficient within a wideband, fractional bandwidth being typically 100%. Autors: Sevda Özdemir;Alper Ünal;Adnan Köksal; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Sep 2017, volume: 65, issue:9, pages: 4790 - 4796 Publisher: IEEE
» Application-Layer FEC Scheme Configuration Optimization via Hybrid Simulated Annealing
 Abstract:An optimization technique based on an adapted combination of simulated annealing (SA) and tabu search (TS) is presented. This method aims at finding near-optimal unequal error protection (UEP) application-layer FEC code configurations. This approach is intended to smartly protect audio and video transmission over IP networks when hard time restrictions apply. The considered code is a UEP version of the widely-used Pro-MPEG COP3 codes enabling the use of several matrices of dissimilar size and thus of unequal recovery capability. Finding the optimal configuration frequently requires the evaluation of a large solution space. So, to fulfill the imposed constraints, SA is adapted to the specifics of the scenario. In particular, the annealing schedule is conditioned by the real-time restrictions. Furthermore, solution neighborhood structures are determined by a proposed definition of distance between protection configurations, which, jointly with TS, conditions the selection of candidate solutions. Experimental results show a significantly improved performance of the optimization process, which invariably fulfills imposed timing constraints, at the expense of a very low distortion increase, when compared to using exhaustive search. These results allow the use of UEP Pro-MPEG COP3 codes for protecting video and audio transmission, which distinctly outperforms the standard code in a wide range of scenarios. Autors: César Díaz;Julián Cabrera;Fernando Jaureguizar;Narciso García; Appeared in: IEEE Transactions on Broadcasting Publication date: Sep 2017, volume: 63, issue:3, pages: 479 - 493 Publisher: IEEE
» Applying Pattern Recognition to High-Resolution Images to Determine Cellular Signaling Status
 Abstract:Two frequently used tools to acquire high- resolution images of cells are scanning electron microscopy (SEM) and atomic force microscopy (AFM). The former provides a nanometer resolution view of cellular features rapidly and with high throughput, while the latter enables visualizing hydrated and living cells. In current practice, these images are viewed by eye to determine cellular status, e.g., activated versus resting. Automatic and quantitative data analysis is lacking. This paper develops an algorithm of pattern recognition that works very effectively for AFM and SEM images. Using rat basophilic leukemia cells, our approach creates a support vector machine to automatically classify resting and activated cells. Ten-fold cross-validation with cells that are known to be activated or resting gives a good estimate of the generalized classification results. The pattern recognition of AFM images achieves 100% accuracy, while SEM reaches 95.4% for our images as well as images published in prior literature. This outcome suggests that our methodology could become an important and frequently used tool for researchers utilizing AFM and SEM for structural characterization as well as determining cellular signaling status and function. Autors: Michael F. Lohrer;Darrin M. Hanna;Yang Liu;Kang-Hsin Wang;Fu-Tong Liu;Ted A. Laurence;Gang-Yu Liu; Appeared in: IEEE Transactions on NanoBioscience Publication date: Sep 2017, volume: 16, issue:6, pages: 438 - 446 Publisher: IEEE
» Approaching Capacity at High Rates With Iterative Hard-Decision Decoding
 Abstract:A variety of low-density parity-check (LDPC) ensembles have now been observed to approach capacity with message-passing decoding. However, all of them use soft (i.e., non-binary) messages and a posteriori probability decoding of their component codes. In this paper, we show that one can approach capacity at high rates using iterative hard-decision decoding (HDD) of generalized product codes. Specifically, a class of spatially coupled generalized LDPC codes with Bose–Chaudhuri–Hocquengham component codes is considered, and it is observed that, in the high-rate regime, they can approach capacity under the proposed iterative HDD. These codes can be seen as generalized product codes and are closely related to braided block codes. An iterative HDD algorithm is proposed that enables one to analyze the performance of these codes via density evolution. Autors: Yung-Yih Jian;Henry D. Pfister;Krishna R. Narayanan; Appeared in: IEEE Transactions on Information Theory Publication date: Sep 2017, volume: 63, issue:9, pages: 5752 - 5773 Publisher: IEEE
» Arc Flash Visible Light Intensity as Viewed From Human Eyes
 Abstract:Human eye can be damaged by the intense light from an arc flash event. Though it is certain that high intensity visible light will be emitted during an arc flash event, there is limited research that provides quantitative light intensity estimation during different arcing incidents as viewed from human eyes. To provide better understanding of the light intensity during arc flash events, this paper proposes an arc flash light intensity estimation model based on approximately 1500 measurement data from arc flash tests using ambient light sensors, which are capable of measuring the light intensity of the arc flash as perceived by the human eyes. The proposed light intensity estimation model can be used to evaluate the potential impact of an arc flash on the human eyes. In addition, the autodarkening welding lens is used in the arc flash testing to explore its effectiveness in attenuating the light intensity and mitigating the exposure to the light hazard during an arc flash event. Autors: Shiuan-Hau Rau;Zhenyuan Zhang;Wei-Jen Lee;David A. Dini; Appeared in: IEEE Transactions on Industry Applications Publication date: Sep 2017, volume: 53, issue:5, pages: 5068 - 5077 Publisher: IEEE
» Architecture of an Ultrasound System for Continuous Real-Time High Frame Rate Imaging
 Abstract:High frame rate (HFR) imaging methods based on the transmission of defocused or plane waves rather than focused beams are increasingly popular. However, the production of HFR images poses severe requirements both in the transmission and the reception sections of ultrasound scanners. In particular, major technical difficulties arise if the images must be continuously produced in real-time, i.e., without any acquisition interruption nor loss of data. This paper presents the implementation of the real-time HFR-compounded imaging application in the ULA-OP 256 research platform. The beamformer sustains an average output sample rate of 470 MSPS. This allows continuously producing coherently compounded images, each of 64 lines by 1280 depths (here corresponding to 15.7 mm width and 45 mm depth, respectively), at frame rates up to 5.3 kHz. Imaging tests addressed to evaluate the achievable speed and quality performance were conducted on phantom. Results obtained by real-time compounding frames obtained with different numbers of steering angles between +7.5° and −7.5° are presented. Autors: Enrico Boni;Luca Bassi;Alessandro Dallai;Valentino Meacci;Alessandro Ramalli;Monica Scaringella;Francesco Guidi;Stefano Ricci;Piero Tortoli; Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control Publication date: Sep 2017, volume: 64, issue:9, pages: 1276 - 1284 Publisher: IEEE
» ARCNET Never Received Enough Credit [History]
 Abstract:In the March 2017 issue of IEEE Industrial Electronics Magazine, the authors of "The Future of Industrial Communication" provided a comprehensive chart of industrial communication milestones ranging from the 1960s to the present [1]. But there was one glaring omission-the Attached Resource Computer Network (ARCNET). As a former chair of the ARCNET Trade Association (ATA), I feel obligated to defend ARCNET as the first local area network (LAN), which is still in use today [2]. It is a technology that impacted both the office and industrial automation industries. It is elegant, fast, robust-and it works! The technology was deemed by the press as "the Rodney Dangerfield of network computing," and its proponents were called fanatical [3]. Although ARCNET has failed to receive the recognition it deserves, it is a successful technology that has been used in applications never imagined by its creators. Autors: George Thomas; Appeared in: IEEE Industry Applications Magazine Publication date: Sep 2017, volume: 23, issue:5, pages: 7 - 13 Publisher: IEEE
» Area Determination of Diabetic Foot Ulcer Images Using a Cascaded Two-Stage SVM-Based Classification
 Abstract:The standard chronic wound assessment method based on visual examination is potentially inaccurate and also represents a significant clinical workload. Hence, computer-based systems providing quantitative wound assessment may be valuable for accurately monitoring wound healing status, with the wound area the best suited for automated analysis. Here, we present a novel approach, using support vector machines (SVM) to determine the wound boundaries on foot ulcer images captured with an image capture box, which provides controlled lighting and range. After superpixel segmentation, a cascaded two-stage classifier operates as follows: in the first stage, a set of k binary SVM classifiers are trained and applied to different subsets of the entire training images dataset, and incorrectly classified instances are collected. In the second stage, another binary SVM classifier is trained on the incorrectly classified set. We extracted various color and texture descriptors from superpixels that are used as input for each stage in the classifier training. Specifically, color and bag-of-word representations of local dense scale invariant feature transformation features are descriptors for ruling out irrelevant regions, and color and wavelet-based features are descriptors for distinguishing healthy tissue from wound regions. Finally, the detected wound boundary is refined by applying the conditional random field method. We have implemented the wound classification on a Nexus 5 smartphone platform, except for training which was done offline. Results are compared with other classifiers and show that our approach provides high global performance rates (average sensitivity = 73.3%, specificity = 94.6%) and is sufficiently efficient for a smartphone-based image analysis. Autors: Lei Wang;Peder C. Pedersen;Emmanuel Agu;Diane M. Strong;Bengisu Tulu; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Sep 2017, volume: 64, issue:9, pages: 2098 - 2109 Publisher: IEEE
» Areal Geometric Effects of a ZnO Charge-Trap Layer on Memory Transistor Operations for Embedded-Memory Circuit Applications
 Abstract:The areal geometric effects of a ZnO charge-trap layer (CTL) on the device characteristics of a charge-trap memory thin-film transistor were investigated for embedded-memory circuit applications. While the device with a larger overlapped region between the CTL and active channel exhibited a larger memory window and faster program speed, in order to guarantee long-term memory retention even under higher drain bias conditions, the CTL size should be minimized to reduce the overlapped area. The resulting device behavior is a compromise between the modulations of the number of trap sites within the ZnO CTL and the electric field concentration caused by the configuration of the edge area in the overlapped region. Autors: Da-Jeong Yun;Jun-Yong Bak;Chun-Won Byun;Sung-Min Yoon; Appeared in: IEEE Electron Device Letters Publication date: Sep 2017, volume: 38, issue:9, pages: 1263 - 1265 Publisher: IEEE
» Array Architectures for 3-D NAND Flash Memories
 Abstract:NAND Flash memories have changed and keep changing our lives. In the past two decades, NAND-based systems, in the form of Flash cards and USB keys, have replaced films and floppy disks. But disruption did not stop there. Today, NAND is really ubiquitous, as it plays the role of storage element inside smartphones and tablets; even further, it is now expanding its reach because solid-state drives (SSDs), i.e., drives built with several NAND devices, are replacing hard disk drives (HDDs) in more and more applications. To fuel this continuous evolution, NAND has to remain very aggressive in terms of cost per bit. When approaching 10-nm technologies, planar NAND is running out of steam: industry and academia have worked hard on finding a solution to this problem for more than a decade. Three-dimensional integration turned out to be the most promising alternative, and it is now eventually reaching the market. This paper is about 3-D NAND Flash memories and the related integration challenges. Charge trap and floating gate 3-D technologies will be discussed with the aid of several bird’s-eye views. Advanced layout techniques will thoroughly be analyzed. Finally, future scaling trends will be presented. Autors: Rino Micheloni;Seiichi Aritome;Luca Crippa; Appeared in: Proceedings of the IEEE Publication date: Sep 2017, volume: 105, issue:9, pages: 1634 - 1649 Publisher: IEEE
» Array Termination Impacts in Advanced SRAM
 Abstract:An essential goal of the static random access memory (SRAM) array termination design is to both terminate as well as maintain a homogeneous environment for the active edge cells in the array. Local layout effects (LLEs) in the array termination design can exert influence on the active array SRAM devices in close proximity to the termination region, which can lead to undesirable inhomogenuities in the array. The impact of LLEs, originating from the array termination design, on SRAM read performance and fail count, are examined using a 14-nm FinFET technology. Large-scale SRAM read performance statistics are analyzed to identify elevated read currents and low-voltage fail counts associated with the array termination. The root cause and modulating factors are explored, and potential solution paths are discussed. Autors: Randy W. Mann;Sandeep Puri;Sheng Xie;Daniel Marienfeld;Joseph Versaggi;Bianzhu Fu;Michael Gribelyuk;Ratheesh R. Thankalekshmi;Xiaoqiang Zhang;Hui Zang;Chad E. Weintraub; Appeared in: IEEE Transactions on Very Large Scale Integration Systems Publication date: Sep 2017, volume: 25, issue:9, pages: 2449 - 2457 Publisher: IEEE
» Arsenic Phosphorus Monolayer: A Promising Candidate for H2S Sensor and NO Degradation With High Sensitivity and Selectivity
 Abstract:The sensing behaviors of arsenic phosphorus (AsP) for nitric oxide (NO) and hydrogen sulfide (H2S) are investigated by means of the density functional theory and the nonequilibrium Green’s function method. The calculated adsorption energy and charge transfer of H2S molecule on silicon-doped AsP (Si-AsP) are 0.352 eV and 0.106 , respectively, indicating the presence of physisorption process. The H2S adsorption on aluminum-doped AsP is a chemisorption process with covalent bond formed. Furthermore, the calculated current–voltage (–) relation clearly shows that the substrate with and without H2S adsorption exhibits distinct responses. This property indicates that Si-AsP is expected to be the high-performance H2S sensor. The chemisorption is also observed in Si-/Al-doped AsP with NO molecule adsorption, suggesting the high potential in the application of NO degradation. Autors: Yingying Zhang;Chunjian Tan;Qun Yang;Huaiyu Ye;Xian-Ping Chen; Appeared in: IEEE Electron Device Letters Publication date: Sep 2017, volume: 38, issue:9, pages: 1321 - 1324 Publisher: IEEE
» Artefacts in Marine Digital Terrain Models: A Multiscale Analysis of Their Impact on the Derivation of Terrain Attributes
 Abstract:Data acquisition artefacts are commonly found in multibeam bathymetric data, but their effects on mapping methodologies using geographic information system techniques have not been widely explored. Artefacts have been extensively studied in terrestrial settings, but their study in a marine context has currently been limited to engineering and surveying technology development in order to reduce their amplitude during data collection and postprocessing. Knowledge on how they propagate to further analyses like environmental characterization or terrain analysis is scant. The goal of this paper is to describe the contribution of different types of artefacts to marine terrain attributes at multiple scales. Using multibeam bathymetric data from German Bank, off Nova Scotia (Canada), digital bathymetric models (DBMs) were computed at five different spatial resolutions. Ten different amplitudes of heave, pitch, roll, and time artefacts were artificially introduced to generate altered DBMs. Then, six terrain attributes were derived from each of the reference and altered DBMs. Relationships between the amplitude of artefacts and the statistical and spatial distributions of: 1) altered bathymetry and terrain attributes surfaces and 2) errors caused by the artefacts were modeled. Spatial similarity between altered and reference surfaces was also assessed. Results indicate that most artefacts impact spatial similarity and that pitch and roll significantly impact the statistical distribution of DBMs and terrain attributes while time and heave artefacts have a more subtle impact. Results also confirm the relationship between spatial data quality and spatial scale, as finer-scale data were impacted by artefacts to a greater degree than broader-scale data. Autors: Vincent Lecours;Rodolphe Devillers;Vanessa L. Lucieer;Craig J. Brown; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Sep 2017, volume: 55, issue:9, pages: 5391 - 5406 Publisher: IEEE
» Assessing the Benefits of Drug Delivery by Nanocarriers: A Partico/Pharmacokinetic Framework
 Abstract:Objective: An in vivo kinetic framework is introduced to analyze and predict the quantitative advantage of using nanocarriers to deliver drugs, especially anticancer agents, compared to administering the same drugs in their free form. Methods: This framework recognizes three levels of kinetics. First is the particokinetics associated with deposition of nanocarriers into tissues associated with drug effect and toxicity, their residence inside those tissues, and elimination of the nanocarriers from the body. Second is the release pattern in time of free drug from the nanocarriers. Third is the pharmacokinetics of free drug, as it relates to deposition and elimination processes in the target and toxicity associated tissues, and total body clearance. A figure of merit, the drug targeting index (DTI), is used to quantitate the benefit of nanocarrier-based drug delivery by considering the effects of preferential deposition of nanoparticles into target tissues and relative avoidance of tissues associated with drug toxicity, compared to drug that is administered in its free form. Results: General methods are derived for calculating DTI when appropriate particokinetic, pharmacokinetic, and drug release rate information is available, and it is shown that relatively simple algebraic forms result when some common assumptions are made. Conclusion: This approach may find use in developing and selecting nanocarrier formulations, either for populations or for individuals. Autors: Ronald A. Siegel;Ameya R. Kirtane;Jayanth Panyam; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Sep 2017, volume: 64, issue:9, pages: 2176 - 2185 Publisher: IEEE
» Assessing the Feasibility of the Use of Video Motion Magnification for Measuring Microdisplacements
 Abstract:There are different techniques for measuring microdisplacements. The purpose of this paper was to ascertain whether a method of video motion magnification (VMM) can be used for measuring such displacements. For this, standard video devices (a digital single-lens reflex camera and a webcam) were used to record subtle movements of an object, and the results of the VMM technique were contrasted with an air-coupled ultrasonic sensing method that could achieve submicrometer accuracy. The results of the VMM technique highly correlate with those achieved using the ultrasonic sensor, showing that the former can accurately measure displacements in the range from about 5 to 40 from a distance of about 1 m. The temporal characteristics of the moving object were well preserved. The VMM technique is an alternative to other modalities for measuring microdisplacements and has the advantage of being noncontact, long-range, and relatively low-cost. Autors: Mateusz P. Popek;Monika E. Danielewska;D. Robert Iskander; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Sep 2017, volume: 66, issue:9, pages: 2329 - 2336 Publisher: IEEE
» Assessment of Macro Fiber Composite Sensors for Measurement of Acoustic Partial Discharge Signals in Power Transformers
 Abstract:This paper presents a performance assessment of macro fiber composite (MFC) sensors for measuring acoustic emission (AE) signals from partial discharges (PD) in power transformers filled with mineral oil. MFC sensors are low-profile and flexible, allowing them to be attached to uneven surfaces, such as a transformer wall. Two types of MFC sensors were assessed: P1 (d33 effect) and P2 (d31 effect), which are optimized for different deformations in the structure, such as elongation and contraction, respectively. In addition, a conventional AE sensor, R15I-AST model from Physical Acoustics South America, was also used as a reference for comparative analysis. Four metrics were applied to the signals: root mean square, energy criterion, Akaike criterion, power spectral density, and correlation. The experimental results indicate a high similarity between the MFC sensors and the conventional AE sensor, which expands the research field in acoustic PD measurement in power transformers by using low-cost and flexible sensors. Autors: Bruno Albuquerque de Castro;Danilo de Melo Brunini;Fabricio Guimarães Baptista;André Luiz Andreoli;José Alfredo Covolan Ulson; Appeared in: IEEE Sensors Journal Publication date: Sep 2017, volume: 17, issue:18, pages: 6090 - 6099 Publisher: IEEE
» Assessment of the Effectiveness of Energy Storage Resources in the Frequency Regulation of a Single-Area Power System
 Abstract:An energy storage resource (ESR) has outstanding ramping capability, but its limited energy disables the provision of regulation service around the clock. As a comparison, a conventional generator (CG) is not restricted by the released energy, but the ramp rate is limited. In this paper, a method is proposed to evaluate the effectiveness of ESRs providing frequency regulation service in a single-area system. We measure the performance of frequency regulation by the standard deviation of system frequency excursions, and define the regulation requirement of an isolated power system as the minimum regulation capacity which satisfies the desired regulation performance. By analyzing the regulation requirements under different combinations of regulation resources, we can quantitatively compare the effectiveness of CGs and ESRs. Case studies show that ESRs can reduce regulation requirements, indicating that they are more effective than CGs in frequency regulation. However, they become less effective and even outperformed by CGs when they constitute a larger portion of the system regulation capacity. Autors: Fang Zhang;Zechun Hu;Xu Xie;Jing Zhang;Yonghua Song; Appeared in: IEEE Transactions on Power Systems Publication date: Sep 2017, volume: 32, issue:5, pages: 3373 - 3380 Publisher: IEEE
» Asymmetric Binary Coding for Image Search
 Abstract:Learning to hash has attracted broad research interests in recent computer vision and machine learning studies, due to its ability to accomplish efficient approximate nearest neighbor search. However, the closely related task, maximum inner product search (MIPS), has rarely been studied in this literature. To facilitate the MIPS study, in this paper, we introduce a general binary coding framework based on asymmetric hash functions, named asymmetric inner-product binary coding (AIBC). In particular, AIBC learns two different hash functions, which can reveal the inner products between original data vectors by the generated binary vectors. Although conceptually simple, the associated optimization is very challenging due to the highly nonsmooth nature of the objective that involves sign functions. We tackle the nonsmooth optimization in an alternating manner, by which each single coding function is optimized in an efficient discrete manner. We also simplify the objective by discarding the quadratic regularization term which significantly boosts the learning efficiency. Both problems are optimized in an effective discrete way without continuous relaxations, which produces high-quality hash codes. In addition, we extend the AIBC approach to the supervised hashing scenario, where the inner products of learned binary codes are forced to fit the supervised similarities. Extensive experiments on several benchmark image retrieval databases validate the superiority of the AIBC approaches over many recently proposed hashing algorithms. Autors: Fumin Shen;Yang Yang;Li Liu;Wei Liu;Dacheng Tao;Heng Tao Shen; Appeared in: IEEE Transactions on Multimedia Publication date: Sep 2017, volume: 19, issue:9, pages: 2022 - 2032 Publisher: IEEE
» Asymmetric Multilevel Diversity Coding Systems With Perfect Secrecy
 Abstract:Secure rate region of the asymmetric multilevel diversity coding systems (AMDCS) with perfect secrecy is investigated in this paper. The eavesdropper may have access to any one but not more than one subset of the channels but can get nothing about the sources, as long as the size of the subset is not above the security level. As the first nontrivial instance, the secure AMDCS (S-AMDCS) with three encoders and security level one is solved. It is shown that linear codes are optimal for this instance. In contrast with the secure symmetric multilevel diversity coding systems, superposition (source separation) is shown to be not optimal for S-AMDCS in general. Autors: Congduan Li;Xuan Guang; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Sep 2017, volume: 66, issue:9, pages: 8558 - 8562 Publisher: IEEE
» Asymmetric Optical Bus Coupler for Interruption-Free Short-Range Connections on Board and Module Level
 Abstract:In this paper, we present a bidirectional interruption-free multimode waveguide coupler for optical bus systems on board and module level. The principle is based on directional core–core coupling and allows for adjustable coupling powers by tuning the overlap area. By adding a bending to one of the coupling partners, it is possible to obtain specific asymmetric coupling rates depending on the coupling direction (module to bus or vice versa). The proposed approach is extensively analyzed by optical simulation (beam propagation method) and measurements including experiments on the attenuation, the coupling rate, and the bit rate performance. Autors: Lukas Lorenz;Krzysztof Nieweglowski;Zaid Al-Husseini;Niels Neumann;Dirk Plettemeier;Klaus-Jürgen Wolter;Thomas Reitberger;Jörg Franke;Karlheinz Bock; Appeared in: Journal of Lightwave Technology Publication date: Sep 2017, volume: 35, issue:18, pages: 4033 - 4039 Publisher: IEEE
» Asymmetrically Clipped Absolute Value Optical OFDM for Intensity-Modulated Direct-Detection Systems
 Abstract:Orthogonal frequency division multiplexing (OFDM) is attracting increasing attention in optical communication systems, thanks to its inherent benefits such as high spectral efficiency and resistance to frequency-selective channels. In this paper, a novel energy and spectrally efficient scheme called asymmetrically clipped absolute value optical OFDM (AAO-OFDM) is proposed for intensity-modulated direct-detection systems. In AAO-OFDM, absolute value optical OFDM (AVO-OFDM) signals on the even subcarriers and asymmetrically clipped optical OFDM (ACO-OFDM) signals on the odd subcarriers are combined for simultaneous transmission, which employs all the subcarriers requiring no dc biases. For AVO-OFDM scheme, the frequency symbols are first modulated on the even subcarriers, which are then fed into an inverse fast Fourier transform block. Afterward, the absolute values of the bipolar time-domain signals are taken to guarantee non-negativity, while their signs are mapped to the complex-valued symbols and modulated on the odd subcarriers. Since there remain unused odd subcarriers, other useful symbols can be modulated on them, which leads to the conventional ACO-OFDM scheme. At the receiver, the ACO-OFDM symbols on the odd subcarriers are demodulated first, which are reconstructed and removed from the received signals. Afterward, the remaining signals are utilized to detect the AVO-OFDM symbols with the aid of the demodulated sign symbols on the odd subcarriers. Theoretical analysis and simulation results show that AAO-OFDM has lower peak-to-average power ratio than other optical OFDM schemes, which makes it less sensitive to the nonlinearity of the optical devices. Furthermore, it achieves better bit error rate performance compared to its counterparts for the same spectral efficiency. Autors: Ruowen Bai;Qi Wang;Zhaocheng Wang; Appeared in: Journal of Lightwave Technology Publication date: Sep 2017, volume: 35, issue:17, pages: 3680 - 3691 Publisher: IEEE
» Asymptotic Outage Analysis of HARQ-IR Over Time-Correlated Nakagami- $m$ Fading Channels
 Abstract:In this paper, outage performance of hybrid automatic repeat request with incremental redundancy (HARQ-IR) is analyzed. Unlike prior analyses, time-correlated Nakagami- fading channel is considered. The outage analysis thus involves the probability distribution analysis of a product of multiple correlated shifted Gamma random variables and is more challenging than prior analyses. Based on the findings of the conditional independence of the received signal-to-noise ratios, the outage probability is exactly derived by using conditional Mellin transform. Specifically, the outage probability of HARQ-IR under time-correlated Nakagami- fading channels can be written as a weighted sum of outage probabilities of HARQ-IR over independent Nakagami fading channels, where the weightings are determined by a negative multinomial distribution. This result enables not only an efficient truncation approximation of the outage probability with uniform convergence but also asymptotic outage analysis to further extract clear insights, which have never been discovered for HARQ-IR even under fast fading channels. The asymptotic outage probability is then derived in a simple form, which clearly quantifies the impacts of transmit powers, channel time correlation, and information transmission rate. It is proved that the asymptotic outage probability is an inverse power function of the product of transmission powers in all HARQ rounds, an increasing function of the channel time correlation coefficients, and a monotonically increasing and convex function of information transmission rate. The simple expression of the asymptotic result enables optimal power allocation and optimal rate selection of HARQ-IR with low complexity. Finally, numerical results are provided to verify our analytical results and justify the application of the asymptotic re- ult for optimal system design. Autors: Zheng Shi;Shaodan Ma;Guanghua Yang;Kam-Weng Tam;Minghua Xia; Appeared in: IEEE Transactions on Wireless Communications Publication date: Sep 2017, volume: 16, issue:9, pages: 6119 - 6134 Publisher: IEEE
» Asymptotically Equivalent Sequences of Matrices and Capacity of a Discrete-Time Gaussian MIMO Channel With Memory
 Abstract:Using some recent results on asymptotically equivalent sequences of matrices, we present in this paper, a new derivation of the capacity formula given by Brandenburg and Wyner for a discrete-time Gaussian multiple-input-multiple-output channel with memory. In this paper, we tackle not only the case considered by them, where the number of channel inputs and the number of channel outputs are the same, but also when both numbers are different. Autors: Jesús Gutiérrez-Gutiérrez;Pedro M. Crespo;Marta Zárraga-Rodríguez;Bjørn Olav Hogstad; Appeared in: IEEE Transactions on Information Theory Publication date: Sep 2017, volume: 63, issue:9, pages: 6000 - 6003 Publisher: IEEE
» Asymptotically Tight Performance Bounds of Diversity Receptions Over $\alpha$-$\mu$ Fading Channels With Arbitrary Correlation
 Abstract:Exact performance analyses over correlated - fading channels result in intractable multifold integrals or infinite series. In this paper, upper and lower bounds are derived for outage probabilities and error rates of maximum-ratio combining (MRC), selection combining (SC), and equal-gain combining (EGC) over the - fading channels with arbitrary correlation. The derived bounds are in closed form and asymptotically tight. Our applied correlation structure uniquely determines the joint probability density function of the - random variables, thus it is a generalization of the other correlation models based on branches’ hyperpower or power correlation. Based on these closed-form bounds, one can easily estimate the performance of MRC, SC, and EGC in large signal-to-noise ratio region, where performing Monte Carlo simulation is time consuming. These new bounds also reveal a fact that SC can in fact outperform EGC under some certain channel conditions. More importantly, these bounds reveal which factors determine the asymptotic performance of diversity reception systems, and provide criteria for system design. Autors: Bingcheng Zhu;Jun Yan;Yongjin Wang;Lenan Wu;Julian Cheng; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Sep 2017, volume: 66, issue:9, pages: 7619 - 7632 Publisher: IEEE
» Asynchronous Multiagent Primal-Dual Optimization
 Abstract:We present a framework for asynchronously solving convex optimization problems over networks of agents which are augmented by the presence of a centralized cloud computer. This framework uses a Tikhonov-regularized primal-dual approach in which the agents update the system's primal variables and the cloud updates its dual variables. To minimize coordination requirements placed upon the system, the times of communications and computations among the agents are allowed to be arbitrary, provided they satisfy mild conditions. Communications from the agents to the cloud are likewise carried out without any coordination in their timing. However, we require that the cloud keeps the dual variable's value synchronized across the agents, and a counterexample is provided that demonstrates that this level of synchrony is indeed necessary for convergence. Convergence rate estimates are provided in both the primal and dual spaces, and simulation results are presented that demonstrate the operation and convergence of the proposed algorithm. Autors: Matthew T. Hale;Angelia Nedić;Magnus Egerstedt; Appeared in: IEEE Transactions on Automatic Control Publication date: Sep 2017, volume: 62, issue:9, pages: 4421 - 4435 Publisher: IEEE
» Asynchronous Networked MPC With ISM for Uncertain Nonlinear Systems
 Abstract:A model-based event-triggered control scheme for nonlinear constrained continuous-time uncertain systems in networked configuration is presented in this paper. It is based on the combined use of model-predictive control (MPC) and integral sliding-mode (ISM) control, and it is oriented to reduce the packet transmission over the network both in the direct path and in the feedback path, in order to avoid network congestion. The key elements of the proposed control scheme are the ISM local control law, the MPC remote controller, a smart sensor, and a smart actuator, both containing a copy of the nominal model of the plant. The role of the ISM control law is to compensate matched uncertainties, without amplifying the unmatched ones. The MPC controller with tightened constraints generates the control component oriented to comply with state and control requirements and is asynchronous since the underlying constrained optimization problem is solved only when a triggering event occurs. In the paper, the robustness properties of the controlled system are theoretically analyzed, proving the regional input-to-state practical stability of the overall control scheme. Autors: Gian Paolo Incremona;Antonella Ferrara;Lalo Magni; Appeared in: IEEE Transactions on Automatic Control Publication date: Sep 2017, volume: 62, issue:9, pages: 4305 - 4317 Publisher: IEEE
» Atom by Atom Simulations of Nanomaterial Manipulation: The Plasma Etching Case
 Abstract:In this paper, we discuss a multiscale method for process simulations with atomic resolution applied to plasma etching. We demonstrate that the accurate prediction of microstructural modifications, as a function of the equipment parameters, can be achieved by coupling two simulation approaches that model phenomena at different length scales. Focusing on the etching processing of nanopatterned silicon samples in HBr/O-type plasma, we highlight the main ingredients of the numerical method: 1) the comprehensive model of plasma reactions to determine the particle distribution of the active plasma components, and 2) a coupled Kinetic Monte-Carlo method simulating all the events concurring to the surface erosion at the atomic level. The technique predicts the variation of the process results when the macroscopic parameters related to equipment settings (e.g., power, potential, and injected gas composition) are modified. A comparison between the microscopic analysis of real structures and the etched profiles predicted by the feature scale simulations validates the coupled numerical approach. Autors: Alessio Campo;Salvatore Francesco Lombardo;Ioannis Deretzis;Giuseppe Garozzo;Giuseppe Gioacchino Neil Angilella;Antonino La Magna; Appeared in: IEEE Transactions on Nanotechnology Publication date: Sep 2017, volume: 16, issue:5, pages: 790 - 797 Publisher: IEEE
» Atomic Force Microscopy in Characterizing Cell Mechanics for Biomedical Applications: A Review
 Abstract:Cell mechanics is a novel label-free biomarker for indicating cell states and pathological changes. The advent of atomic force microscopy (AFM) provides a powerful tool for quantifying the mechanical properties of single living cells in aqueous conditions. The wide use of AFM in characterizing cell mechanics in the past two decades has yielded remarkable novel insights in understanding the development and progression of certain diseases, such as cancer, showing the huge potential of cell mechanics for practical applications in the field of biomedicine. In this paper, we reviewed the utilization of AFM to characterize cell mechanics. First, the principle and method of AFM single-cell mechanical analysis was presented, along with the mechanical responses of cells to representative external stimuli measured by AFM. Next, the unique changes of cell mechanics in two types of physiological processes (stem cell differentiation, cancer metastasis) revealed by AFM were summarized. After that, the molecular mechanisms guiding cell mechanics were analyzed. Finally the challenges and future directions were discussed. Autors: Mi Li;Dan Dang;Lianqing Liu;Ning Xi;Yuechao Wang; Appeared in: IEEE Transactions on NanoBioscience Publication date: Sep 2017, volume: 16, issue:6, pages: 523 - 540 Publisher: IEEE
» Attenuation of Stray Magnetic Field in Inductive Power Transfer by Controlling Phases of Windings’ Currents
 Abstract:Significant stray magnetic field exists around the inductive-power-transfer (IPT) coils owning to the large gap between transmitter and receiver. In this paper, the field is attenuated by controlling the phases of windings’ currents. The relationship between magnetic field and windings’ currents is analyzed according to the diagrams of phasors. The dual-side-controlled converter is used for circuit realization, in which the inverter and rectifier with MOSFETs bridges are implemented on both the transmitter side and receiver side. The pulsewidths of the voltages for the inverter and rectifier control the currents magnitudes, whereas the phases of the voltages control the currents phases. The effectiveness of field attenuation with this method was verified in both simulation and experiment, for the IPT system with series-series compensation. The stray magnetic field was reduced by up to 30% when the phase difference is 50° between transmitter current and receiver current, compared to the conventional case with passive rectifier when the phase difference is 90°. The increase of winding losses is also analyzed. Autors: Ming Lu;Khai D. T. Ngo; Appeared in: IEEE Transactions on Magnetics Publication date: Sep 2017, volume: 53, issue:9, pages: 1 - 8 Publisher: IEEE
» Audio Identification by Sampling Sub-fingerprints and Counting Matches
 Abstract:It is challenging to retrieve audio clips from large audio datasets not only due to the high dimensionality of audio but also due to the large number of audios. Fingerprinting methods primarily focus on the use of semantic-level techniques to speed up retrieval and neglect low-level support. This paper shows that the performance of audio retrieval can be exploited by properly organizing and manipulating audio fingerprint data. The proposed sampling and counting method markedly improves the retrieval speed while maintaining a high recall rate and high precision for short audio clips. The proposed inverted index structure for fingerprints quickly shrinks the scope of the candidate set while requiring considerably less memory. The experiments show that the proposed method is faster and yields more consistent performance in terms of recall rate and precision than do the state-of-the-art methods. The proposed method is scalable for big audio data and is robust to background noise, resampling, MP3 conversion, white noise addition, bandpass filtering, chorus, echo, flanger, gsm compression, and tremolo. The average precision and recall rates are 99.995% and 99.78%, respectively, for dataset 1 and average 98.97% and 95.15%, respectively, for dataset 2. Specifically, the precision and recall rates for query audio clips of 3 s in length in the targeted dataset 1 are 99.94% and 99.64%, respectively. Autors: Shanshan Yao;Baoning Niu;Jianquan Liu; Appeared in: IEEE Transactions on Multimedia Publication date: Sep 2017, volume: 19, issue:9, pages: 1984 - 1995 Publisher: IEEE