#### Electrical and Electronics Engineering publications abstract of: 07-2017 sorted by title, page: 7

» Evanescently Coupled Waveguide InGaAs UTC-PD Having an Over 21 GHz Bandwidth Under Zero Bias
 Abstract:The design and fabrication of an evanescently coupled waveguide InGaAs unitraveling-carrier photodiode (PD) are presented. Through doping the InGaAs absorption layer gradedly, a large built-in electric field can be obtained. As a result, a 4--wide 15--long PD has a bandwidth larger than 21 GHz at zero bias. Passive input waveguide is integrated monolithically with the PD by a simple process, which eases the integration of PD with other optical components. Autors: Siwei Sun;Song Liang;Junjie Xu;Limeng Zhang;Lu Guo;Xiao Xie;Hongliang Zhu;Wei Wang; Appeared in: IEEE Photonics Technology Letters Publication date: Jul 2017, volume: 29, issue:14, pages: 1155 - 1158 Publisher: IEEE
» Event-Based State Estimation of Hidden Markov Models Through a Gilbert–Elliott Channel
 Abstract:In this note, the problem of event-based state estimation for a finite-state hidden Markov model under a generic stochastic event-triggering condition and an unreliable communication channel is investigated. The effect of packet dropout is characterized with a Gilbert–Elliott process. Utilizing the change of probability measure approach, the packet dropout model and the event-triggered measurement information available to the estimator, analytical expressions for the conditional probability distributions of the states are obtained, based on which the optimal event-based state estimates can be further calculated, together with a closed-form expression of the average sensor-to-estimator communication rate. The effectiveness of the proposed results is illustrated by an application to a wireless automated machine health monitoring problem. Autors: Wentao Chen;Junzheng Wang;Dawei Shi;Ling Shi; Appeared in: IEEE Transactions on Automatic Control Publication date: Jul 2017, volume: 62, issue:7, pages: 3626 - 3633 Publisher: IEEE
» Event-Driven Energy Metering: Principles and Applications
 Abstract:Recent developments in smart metering applications have led to the conceptualization and construction of a new type of energy meter, operating on the basis of event-driven principles. The event-driven metering concepts are applied to represent the information on the electrical load patterns, which have an integral value. This paper explains why these concepts are different from the ones used for event-based applications in other domains, discusses the principles used in the new type of electricity meter, presents the data formats structured in such a way to provide detailed knowledge representation, and shows a number of results on real-case applications. A specific index is defined in order to represent the effectiveness of the event-driven metering scheme illustrated to represent the details of the metered pattern, comparing the results with the ones that could be reached in the most favorable case through regular timer-driven metering. The presentation of specific applications based on real-life datasets highlights the advantages of the event-driven energy metering over the traditional timer-driven metering scheme. Autors: Mikhail Simonov;Gianfranco Chicco;Gianluca Zanetto; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3217 - 3227 Publisher: IEEE
» Event-Triggered Mean-Square Consensus Control for Time-Varying Stochastic Multi-Agent System With Sensor Saturations
 Abstract:In this technical note, the consensus control problem is investigated for a class of discrete time-varying stochastic multi-agent system subject to sensor saturations. An event-based mechanism is adopted where each agent updates the control input signal only when the pre-specified triggering condition is violated. To reflect the time-varying manner and characterize the transient consensus behavior, a new index for mean-square consensus is put forward to quantify the deviation level from individual agent to the average value of all agents’ states. For a fixed network topology, the aim of the proposed problem is to design time-varying output-feedback controllers such that, at each time step, the mean-square consensus index of the closed-loop multi-agent system satisfies the pre-specified upper bound constraints subject to certain triggering mechanism. Both the existence conditions and the explicit expression of the desired controllers are established by resorting to the solutions to a set of recursive matrix inequalities. An illustrative simulation example is utilized to demonstrate the usefulness of the proposed algorithms. Autors: Lifeng Ma;Zidong Wang;Hak-Keung Lam; Appeared in: IEEE Transactions on Automatic Control Publication date: Jul 2017, volume: 62, issue:7, pages: 3524 - 3531 Publisher: IEEE
» Evolution of Activation Energy of Interface Traps in LPNP Transistors Characterized by Deep-Level Transient Spectroscopy
 Abstract:The emission of charge carriers from the interface traps as a function of irradiation dose and bias voltage is investigated in terms of Poole–Frenkel effect (PFE) used by deep-level transient spectroscopy (DLTS). The electrical properties in lateral PNP (LPNP) transistors caused by Co60 gamma-ray radiation are measured in situ during irradiation, showing that the interface traps give the main contribution to the excess base current of LPNP transistors. Based on the DLTS results, with increasing irradiation dose, the density of the charged positive interface traps at a given bias voltage increases. This causes an increase in the electric-field strength in the space-charge region and a decrease in the activation energy of interface traps and an increase in the emission rate of charge carriers from the interface traps, showing a similar feature to the classical PFE. However, the charge sign of the interface traps changes from negative to positive, which is different to the classical PFE, and thus displays a new mode of PFE. In order to confirm this conclusion, various bias conditions are employed during DLTS measurements. With decreasing the reverse bias, the electric-field strength increases, leading to an obvious decrease in activation energy of the interface traps and increase in emission rate of charge carriers. Moreover, the interface traps are shown to be uniformly located at the Si/SiO2 interface, and the uniformly distributed interface traps give the new PFE mode, which is independent of the position in depletion layer. Autors: Xingji Li;Jianqun Yang;Chaoming Liu; Appeared in: IEEE Transactions on Nuclear Science Publication date: Jul 2017, volume: 64, issue:7, pages: 1905 - 1911 Publisher: IEEE
» Evolutionary Channel Sharing Algorithm for Heterogeneous Unlicensed Networks
 Abstract:Channel sharing in TV whitespace (TVWS) is challenging because of signal propagation characteristics and diversity in network technologies employed by secondary networks coexisting in TVWS. In this paper, the TVWS sharing problem is modeled as a multiobjective optimization problem, where each objective function tackles an important coexisting requirement, such as interference and disparity in network technologies. We propose an evolutionary algorithm that shares the TVWS among coexisting networks taking care of their channel occupancy requirements. In this paper, the channel occupancy is defined as the time duration; a network desires to radiate on a channel to achieve its desired duty cycle. Simulation results show that the proposed algorithm outperforms existing TVWS sharing algorithms regarding allocation fairness and a fraction of channel occupancy requirements of the coexisting networks. Autors: M. A. Raza;Sangjun Park;Heung-No Lee; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4378 - 4389 Publisher: IEEE
» Examination of Three Different ACOPF Formulations With Generator Capability Curves
 Abstract:This paper examines three different formulations of AC optimal power flow problem and compares performance of well-established general-purpose optimization algorithms for each, over different initial conditions. Polar power–voltage, rectangular power–voltage, and rectangular current–voltage are formulated to evaluate ACOPF solution characteristic. The formulation here maintains line flows as explicit variables and employs summations of these quantities to impose conservation conditions at each node. Two representations of line thermal limits are considered, one using real power (to allow comparisons to dc power flow approximations), and a more physically based ampacity limit using current magnitude. Nonlinear generator capability curves are represented (“D-curves”), including options to allow active and reactive limits dependent on generator voltage. A uniform objective function is used throughout, that of minimizing quadratic generator operating cost curves. Numerical performance case studies are performed for these formulations over six different classes of initial conditions, evaluating computational time and also robustness of convergence. Autors: Byungkwon Park;Lisa Tang;Michael C. Ferris;Christopher Lawson DeMarco; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 2913 - 2923 Publisher: IEEE
» Existence and Continuity of Differential Entropy for a Class of Distributions
 Abstract:In this letter, we identify a class of absolutely continuous probability distributions, and show that the differential entropy is uniformly convergent over this space under the metric of total variation distance. One of the advantages of this class is that the requirements could be readily verified for a given distribution. Autors: Hamid Ghourchian;Amin Gohari;Arash Amini; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1469 - 1472 Publisher: IEEE
» Existence and Uniqueness of Load-Flow Solutions in Three-Phase Distribution Networks
 Abstract:We present sufficient conditions for the existence and uniqueness of load-flow solutions in three-phase distribution networks. The conditions can be efficiently verified for real distribution systems. Autors: Cong Wang;Andrey Bernstein;Jean-Yves Le Boudec;Mario Paolone; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3319 - 3320 Publisher: IEEE
» Experimental and Numerical Study of the Electrostatic Separation of Two Types of Copper Wires From Electric Cable Wastes
 Abstract:Electrostatic separators are not commonly used for the selective sorting of different sorts of metals contained in a granular mixture. However, the separation might be possible if their characteristics (density, conductivity, size, etc.) are different enough. The aim of this paper is to evaluate the feasibility of sorting tinned and bare copper strands (length: 2–5 mm; diameter: 0.8–1.6 mm) contained in granular electric cable wastes using a roll-type electrostatic separator with three different high-voltage electrode configurations: plate; S-shaped; and reverse S-shaped. Experimental design methodology is used to investigate the effects of three factors: 1) high voltage applied to the electrode; 2) system, inclination of the high-voltage electrode; and 3) interelectrode distance. The recovery and purity of the bare copper product are evaluated for each experiment. The best results of the electrostatic separation experiments are obtained with the reversed S-shaped electrode configuration (recovery of 55.4% of the bare copper wire in a product having a copper content of 85.1%). Numerical modeling and experimental visualization of particle trajectories facilitate the interpretation of the electrostatic separation experimental results. Autors: Gontran Richard;Abdelhady Ragab Salama;Karim Medles;Cédric Lubat;Seddik Touhami;Lucian Dascalescu; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3960 - 3969 Publisher: IEEE
» Experimental Demonstration of ASE Noise Suppression by Soliton Self-Frequency Shift
 Abstract:Amplified spontaneous emission (ASE) noise self-suppression effect on soliton self-frequency shift (SSFS) has been already reported, but its experimental verification has not been demonstrated. In this letter, we experimentally demonstrate ASE noise suppression effect on SSFS using a metric of power penalty on bit error rate (BER) for on–off keying signals before and after ASE noise suppression. We added an additional 1% of ASE noise to the signal generated from an erbium-doped fiber amplifier. In addition, we examined the degradation of power penalties on BER for different percentages of the noise in the signal in simulation to assess the effective range of ASE noise suppression on SSFS. Autors: Y. Yamasaki;T. Nagashima;M. Hiraoka;T. Konishi; Appeared in: IEEE Photonics Technology Letters Publication date: Jul 2017, volume: 29, issue:14, pages: 1167 - 1170 Publisher: IEEE
» Experimental Investigation of Electron Collection by Rectangular Cuboid Probes in a High-Speed Plasma
 Abstract:This paper describes ground-based scaled plasma experiments that simulated picosatellite and femtosatellite electron collection in the low earth orbit (LEO) ionospheric plasma, capturing special characteristics of these small spacecraft, including their possible rectangular cuboid shape, size relative to the plasma Debye length and the electron thermal gyroradius, and orientation with respect to plasma flow and magnetic field. It was observed that enhancing magnetic field strength to an appropriately scaled value to approximate LEO decreased the electron saturation current. The current collection characteristics were also impacted by the orientation of the probes relative to the magnetic field and the direction of plasma flow. In the voltage range tested, a model used in previous studies to predict electron saturation current underestimated the measured probe currents by a factor of two or more. Semi-empirical models developed here to calculate electron saturation currents that were within 10% of the measured currents. This experimental analysis enhances our understanding of current collection by rectangular cuboid probes in high-speed plasmas. Autors: Iverson C. Bell;Omar Leon;Grant C. Miars;Brian E. Gilchrist; Appeared in: IEEE Transactions on Plasma Science Publication date: Jul 2017, volume: 45, issue:7, pages: 1788 - 1802 Publisher: IEEE
» Experimental Investigation of Piezoresistive Effect in p-Type 4H–SiC
 Abstract:This letter presents for the first time the piezoresistive effect in p-type 4H–SiC. Longitudinal and transverse p-type 4H–SiC piezoresistors with a doping concentration of cm were fabricated along [] directions. Ni/Al electrodes annealed at 1000 °C showed a good ohmic contact, and then, the longitudinal and transverse gauge factors were found to be as high as 31.5 and −27.3, respectively. The large gauge factors, attributed to the change of valance energy bands upon application of mechanical strain, and the linear relationship between the resistance change versus induced strain demonstrate the potential of p-type 4H–SiC for mechanical sensing applications. Autors: Tuan-Khoa Nguyen;Hoang-Phuong Phan;Toan Dinh;Jisheng Han;Sima Dimitrijev;Philip Tanner;Abu Riduan Md Foisal;Yong Zhu;Nam-Trung Nguyen;Dzung Viet Dao; Appeared in: IEEE Electron Device Letters Publication date: Jul 2017, volume: 38, issue:7, pages: 955 - 958 Publisher: IEEE
» Experimental Investigation of Rotor Currents Distribution in the Healthy and Faulty Cage of Induction Motors at Standstill
 Abstract:This paper simply investigates experimentally multiple “rotor” bar current waveforms at standstill, on a dedicated inverted induction motor prototype as a basis to analyze the bar currents distribution in the symmetrical and unsymmetrical cage. A phasor calculus scheme based on primary magneto-motive-force space harmonics is developed to explain this asymmetry of bar currents system at standstill even for a symmetrical cage. The results of the paper should be a strong experimental foundation to investigate thoroughly the effects of rotor speed and loading and of broken bars on additional losses, torque pulsations, noise, and vibrations in high performance induction machines. Autors: Gheorghe Madescu;Marius Biriescu;Lucian Nicolae Tutelea;Martian Mot;Marcus Svoboda;Ion Boldea; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Jul 2017, volume: 64, issue:7, pages: 5305 - 5313 Publisher: IEEE
» Experimental Validation of Comprehensive Steady-State Analytical Model of Bidirectional WPT System in EVs Applications
 Abstract:A flexible, automatic, reliable, and safe charging and discharging system for electric vehicles (EVs) and hybrid EVs is crucial in vehicle-to-grid (V2G) operation. The bidirectional inductive wireless power transfer system (BIWPTS) is an ideal solution in this situation. With authentic power-flow models for the BIWPTS in hand, designers and operators can predict, optimize, and analyze the interaction performance between the EV and the grid. Thus, this paper presents a harmonics-based theoretical power-flow model for BIWPTS for charging and discharging EVs in V2G applications. The proposed model provides accurate estimation for the active and reactive power flow during V2G and grid-to-vehicle modes. Moreover, the impact of the circuit losses and harmonics, due to the high-frequency power inverters, on the power-flow performance is investigated. This effect is stated mathematically by four novel power-flow criteria formulas. New conditions for achieving maximum active and reactive power, and unity and zero power-factor system operation, are also developed. The sensitivity of the circuit performance to the variation of its parameters has been studied. For validation purposes, a computer-based model and experimental platform of BIWPTS for EV applications are developed and tested. The comparison between the theoretical, simulation, and experimental results verified the proposed models and analysis. Autors: Ahmed A. S. Mohamed;Alberto Berzoy;Osama A. Mohammed; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5584 - 5594 Publisher: IEEE
» Experimental Verification of Rotor Demagnetization in a Fractional-Slot Concentrated-Winding PM Synchronous Machine Under Drive Fault Conditions
 Abstract:This paper presents the results of experimental tests designed to verify analytical predictions of the rotor demagnetization characteristics of a 0.6 kW (cont.) 9-slot/6-pole fractional-slot concentrated winding (FSCW) interior permanent magnet (IPM) synchronous machine. The demagnetization characteristics of the rotor magnets in this commercially produced FSCW-IPM machine are measured using a test configuration that is designed to conduct multiple demagnetization tests on the same test machine under controlled temperature conditions. In this paper, finite-element (FE) predictions of the rotor demagnetization characteristics of the experimental machine during three-phase symmetrical short-circuit and single-phase asymmetrical short-circuit faults are presented. These results are compared with experimental test measurements of the postfault currents and the magnet flux density distribution following demagnetization, demonstrating very good agreement of many key features. These comparisons also confirm that 3-D effects and magnet material properties such as the magnet thermal coefficients have a significant impact on some details of the FE predictions of the machine's fault-mode response characteristics. Autors: Gilsu Choi;Yichao Zhang;T. M. Jahns; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3467 - 3475 Publisher: IEEE
» Experimentally Calibrated Thermal Stator Modeling of AC Machines for Short-Duty Transient Operation
 Abstract:This paper presents an approach to the thermal design of an ac machine where the application requires low-duty transient operation. To provide accurate temperature predictions, the design process has been informed with experimental data from tests on a stator-winding sector (motorette). These have been shown to be a time and cost-effective means of calibrating the thermal model of a full machine assembly, prior to manufacture of the final design. Such an approach is usually adopted in design analysis of machines with a concentrated winding topology. Here, the motorette testing has been extended to a machine with a distributed winding. Several alternate slot liner and impregnating materials have been evaluated to maximize the heat transfer from the winding body into the machine periphery, and a total of nine stator section samples have been manufactured and tested. The performance tradeoffs between the various combinations are discussed in detail alongside their ability to satisfy the design requirements. Based upon these experimental results, the most promising designs have been selected for transient duty analysis against the design specification. A lumped parameter thermal model has been used for this purpose and calibrated using the data from the subassembly testing. Experimental results on the full machine assembly are presented, showing good correlation with the motorette calibrated thermal model. Autors: Jonathan Godbehere;Rafal Wrobel;David Drury;Phil H. Mellor; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3457 - 3466 Publisher: IEEE
» Exploiting the Fast Spectral Roll-Off of CPM Sidelobes to Improve Bandwidth Efficiency in Satellite Communications
 Abstract:Simple and efficient carrier-overlapping and interference-reduction techniques are addressed for frequency-division multiplexing–continuous phase modulation (FDM–CPM) schemes. CPM carriers are densely multiplexed (packed) in the frequency-domain, without leaving any guard bands, thus allowing frequency content in adjacent bands to overlap, so as to enhance the bandwidth efficiency. The intentional adjacent channel interference, introduced by carrier-overlapping during transmission, is combated at the receiver front-end using simple interference-reduction filters that are designed to exploit the fast roll-off of CPM spectral sidelobes. The receiver back-end is governed by a serially concatenated CPM iterative demodulation/decoding detector. Numerically optimal carrier-packing ratios are determined with respect to information-theoretic bounds. The presented method does not require cooperation among users, and is extended to QAM and PSK schemes as well. Bit error rate analyses show that the proposed non-cooperative receiver design facilitates bandwidth and energy-efficient communication for both the nonlinear and linear satellite channels, without resorting to multiuser detectors, and becomes an attractive solution when cooperation may not be feasible among users that are geographically spread-out. Autors: Ulaş Güntürkün; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1461 - 1464 Publisher: IEEE
» Exploiting Traveling Information for Data Forwarding in Community-Characterized Vehicular Networks
 Abstract:In intelligent vehicular communication networks, a hybrid communication architecture is used which combines both centralized and ad hoc transmission schemes. In order to maximize the end-to-end delivery ratio while reducing the network overhead, one important problem is to efficiently design the data forwarding algorithm to guarantee the quality of data transmission. In this paper, by considering the traveling information and vehicular space-crossing community structure, two metrics, “space–time approachability” and “social approachability,” are defined to provide the absolute and relative geographical information of the forthcoming contacts, respectively. Then, a novel data-forwarding algorithm, called approachability-based algorithm, is proposed, which utilizes two metrics together for better routing quality. We evaluate the proposed approachability-based algorithm utilizing San Francisco Cabspotting and Shanghai Taxi Movement datasets. Simulation results show that the approachability-based data forwarding algorithm can achieve better performance than the popular data forwarding algorithms ZOOM and BUBBLE RAP in all the interested scenarios. Autors: Zhong Li;Cheng Wang;Lu Shao;Chang-Jun Jiang;Cheng-Xiang Wang; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6324 - 6335 Publisher: IEEE
» Exploring Spatial Focusing Effect for Spectrum Sharing and Network Association
 Abstract:Next-generation wireless networks are expected to support an exponentially increasing number of users and demands of data, which all rely on the essential media: spectrum. Spectrum sharing among heterogeneous networks is a fundamental issue that determines network performance. Previous works have focused on a “dynamic spectrum access” mode associated with the cognitive radio technology. These works all focused on the discovery of available spectrum resource either in the time domain or in the frequency domain, i.e., by separating different users’ transmission. To initiate a new paradigm of spectrum sharing, the unique characteristics of the technologies should be utilized in the next-generation networks. The 5G networks are featured either by wide bandwidth like mm-wave systems, or by large-scale antennas like massive MIMO. Those two trends can lead to a common phenomenon: the spatial focusing effect. Based on this focusing effect, we propose a general spatial spectrum sharing framework that enables concurrent multi-users spectrum sharing without the requirement of orthogonal resource allocation. Moreover, we design two general network association protocols either in a centralized manner or in a distributed manner. Simulation results show that both the time reversal wideband and the massive MIMO system can achieve high throughput performance with the spatial spectrum sharing scheme. Autors: Chunxiao Jiang;Beibei Wang;Yi Han;Zhung-Han Wu;K. J. Ray Liu; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4216 - 4231 Publisher: IEEE
» Exponentially Weighted Particle Filter for Simultaneous Localization and Mapping Based on Magnetic Field Measurements
 Abstract:This paper presents a simultaneous localization and mapping (SLAM) method that utilizes the measurement of ambient magnetic fields present in all indoor environments. In this paper, an improved exponentially weighted particle filter was proposed to estimate the pose distribution of the object and a Kriging interpolation method was introduced to update the map of the magnetic fields. The performance and effectiveness of the proposed algorithms were evaluated by simulations on MATLAB based on a map with magnetic fields measured manually in an indoor environment and also by tests on the mobile devices in the same area. From the tests, two interesting phenomena have been discovered; one is the shift of location estimation after sharp turning and the other is the accumulated errors. While the latter has been confirmed and investigated by a few researchers, the reason for the first one still remains unknown. The tests also confirm that the interpolated map by using the proposed method improves the localization accuracy. Autors: Xinheng Wang;Congcong Zhang;Fuyu Liu;Yuning Dong;Xiaolong Xu; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Jul 2017, volume: 66, issue:7, pages: 1658 - 1667 Publisher: IEEE
» Extended Chirp Scaling-Baseband Azimuth Scaling-Based Azimuth–Range Decouple $L_{1}$ Regularization for TOPS SAR Imaging via CAMP
 Abstract:This paper proposes a novel azimuth–range decouple-based regularization imaging approach for the focusing in terrain observation by progressive scans (TOPS) synthetic aperture radar (SAR). Since conventional regularization technique requires transferring the (2-D) echo data into a vector and reconstructing the scene via 2-D matrix operations leading to significantly more computational complexity, it is very difficult to apply in high-resolution and wide-swath SAR imaging, e.g., TOPS. The proposed method can achieve azimuth–range decouple by constructing an approximated observation operator to simulate the raw data, the inverse of matching filtering (MF) procedure, which makes large-scale sparse reconstruction, or called compressive sensing reconstruction of surveillance region with full- or downsampled raw data in TOPS SAR possible. Compared with MF algorithm, e.g., extended chirp scaling-baseband azimuth scaling, it shows huge potential in image performance improvement; while compared with conventional regularization technique, it significantly reduces the computational cost, and provides similar image features. Furthermore, this novel approach can also obtain a nonsparse estimation of considered scene retaining a similar background statistical distribution as the MF-based image, which can be used to the further application of SAR images with precondition being preserving image statistical properties, e.g., constant false alarm rate detection. Experimental results along with a performance analysis validate the proposed method. Autors: Hui Bi;Bingchen Zhang;Xiao Xiang Zhu;Chenglong Jiang;Wen Hong; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Jul 2017, volume: 55, issue:7, pages: 3748 - 3763 Publisher: IEEE
» Fabrication of an Assembled Scanning Probe With Nitrogen Vacancy Centers in Diamond Particle
 Abstract:Nitrogen vacancy (NV−) centers possess exceptional sensitivity to magnetic field even under ambient condition. The optically detectable electron spins and the atomic size make it a promising candidate for the advanced magnetic resonance imaging technique with nanoscale spatial resolution. In this work, we report on a novel method of seeking diamond particles with NV− centers quickly and precisely and fabrication of a silicon scanning probe with NV− centers in diamond as a magnetic sensor. The diamond particles with NV − centers, deposited by microwave plasma chemical vapor deposition under gaseous N2 dopant deliberately, were fixed on the fabricated scanning probe as a magnetic sensor. The silicon scanning probe was fabricated using microfabrication technologies. While the existence of NV− center in diamond particle was determined by Raman spectroscopy, the photoluminescence intensity at 2.87 GHz microwave frequency was decreased by an optically detected magnetic resonance system. It implies that the NV− spin state can be manipulated and read out using optical excitation. Autors: Minjie Zhu;Masaya Toda;Takahito Ono; Appeared in: IEEE Transactions on Nanotechnology Publication date: Jul 2017, volume: 16, issue:4, pages: 545 - 550 Publisher: IEEE
» Fabrication of Inline Micro Air Cavity With Choice-Based Dimensions
 Abstract:We propose a highly effective, and reproducible procedure for the fabrication of inline micro air cavity which plays a vital role in Fabry-Perot-based interferometric sensors. The micro air cavity is fabricated by splicing the single-mode fiber with hollow core photonic crystal fiber (HCPCF) and its dimensions can be well controlled by controlling a series of parameters, such as length of HCPCF and various splicing parameters, such as taper length, overlap of two fibers, and a number of arcs. Experimental results show that microcavities with horizontal and vertical length ranging from very low values ( and ) to very high values ( and ) has been fabricated with high reproducibility. This procedure can be employed to fabricate micro air cavities with any dimension within this range depending upon the user requirement. Furthermore, an application of the micro air cavity-based probes is studied by analyzing the response of one of the probe to axial strain. Autors: Jitendra Narayan Dash;Rajan Jha; Appeared in: IEEE Photonics Technology Letters Publication date: Jul 2017, volume: 29, issue:14, pages: 1147 - 1150 Publisher: IEEE
» Fair Transmission Rate Adjustment in Cooperative Vehicle Safety Systems Based on Multi-Agent Model Predictive Control
 Abstract:Cooperative vehicle safety systems (CVSSs) rely on vehicular networking for broadcasting state information in order to track neighbors’ positions and, therefore, to predict potential collisions. In vehicular networking, a large number of vehicles compete for access to the limited channel resource, causing channel congestion. The vehicle tracking accuracy, which is the basis for CVSSs, therefore, can be heavily affected. Moreover, the available channel resources must be shared among vehicles in a fair way in order to maintain accurate tracking accuracy for each vehicle. To realize fair access to channel resources while maintaining an accurate tracking performance under conditions of dynamic vehicle density, in this paper, we present a distributed fair transmission rate control strategy, based on multi-agent model predictive control (MPC). We first propose a dynamic information dissemination rate model to capture the state information dissemination ability under conditions of dynamic vehicle density. Then, we present a multi-agent information dissemination model, in which each vehicle is controlled by a control agent that uses MPC and coordinates with its neighboring agents in order to determine its optimal transmission rate actions. We then design an augmented-Lagrangian-based distributed decision-making scheme to find the optimal transmission rate actions and, at the same time, reach an agreement on fair and efficient channel utilization among the vehicles. Simulation results confirm that the distributed transmission rate control strategy can guarantee fair access to channel resources while achieving the optimal vehicle tracking performance under conditions of dynamic vehicle density. Autors: Fuxin Zhang;Guozhen Tan;Chao Yu;Nan Ding;Caixia Song;Mingjian Liu; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6115 - 6129 Publisher: IEEE
» Fan Performance Analysis for Rotor Cooling of Axial Flux Permanent Magnet Machines
 Abstract:The thermal management of an axial flux permanent magnet (AFPM) machine is essential because it determines the machine's continuous power output and reliability. In this paper, a secondary cooling method is proposed using rotor cooling, which allows better thermal management on the permanent magnets that are attached to the rotor. This will reduce the potential of the machine failing due to magnet demagnetization and degradation. Thermal analysis via lumped parameter networks is usually sufficient in predicting the motor's thermal behavior. However, the accuracy of the prediction can be increased, especially for the devices with complex flow regions by computational fluid dynamics. In this study, the fan blade was attached to the rotor of a yokeless and segmented armature machine for flow validation and then three different fan blade designs from other engineering applications were tested. The evaluation includes the flow characteristic, power requirement, and thermal characteristic for the AFPM's rotor cooling applications. Additionally, the rotor cooling performance index is introduced to assess each fan design performance. Autors: Ahmad Syahid Fawzal;Remus M. Cirstea;Konstantinos N. Gyftakis;Tim J. Woolmer;Mike Dickison;Mike Blundell; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3295 - 3304 Publisher: IEEE
» Farewell Message From the Outgoing Editor-in-Chief
 Abstract: Autors: Y. Fang; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5515 - 5516 Publisher: IEEE
» Fast Adaptation of Activity Sensing Policies in Mobile Devices
 Abstract:With the proliferation of sensors, such as accelerometers, in mobile devices, activity and motion tracking has become a viable technology to understand and create an engaging user experience. This paper proposes a fast adaptation and learning scheme of activity tracking policies when user statistics are unknown a priori, varying with time, and inconsistent for different users. In our stochastic optimization, user activities are required to be synchronized with a backend under a cellular data limit to avoid overcharges from cellular operators. The mobile device is charged intermittently using wireless or wired charging for receiving the required energy for transmission and sensing operations. First, we propose an activity tracking policy by formulating a stochastic optimization as a constrained Markov decision process (CMDP). Second, we prove that the optimal policy of the CMDP has a threshold structure using a Lagrangian relaxation approach and the submodularity concept. We accordingly present a fast Q-learning algorithm by considering the policy structure to improve the convergence speed over that of conventional Q-learning. Finally, simulation examples are presented to support the theoretical findings of this paper. Autors: Mohammad Abu Alsheikh;Dusit Niyato;Shaowei Lin;Hwee-Pink Tan;Dong In Kim; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5995 - 6008 Publisher: IEEE
» Fast Adaptive Evolutionary PM Traction Motor Optimization Based on Electric Vehicle Drive Cycle
 Abstract:This paper introduces an evolutionary optimization procedure for the design of permanent-magnet motors (PMMs) for electric vehicle (EV) applications, considering a specific drive cycle with multiple operating points. For the purposes of the analysis, the New European Drive Cycle (NEDC) has been employed with two alternative PMM configurations. Energy distribution over the NEDC for a small passenger's EV has been calculated and the equivalent multiple operating points have been extracted, using appropriate weights, in order to maintain an equal energy consumption basis, resulting in reduced computational cost. The proposed optimization technique is constituted of an adaptive differential evolution (DE) algorithm involving dynamic variation of the mutation factor, combined with finite-element (FE) and circuit models. The procedure is based on the precise calculation of the two axes input current components for each candidate solution and operating condition. The methodology introduced presents stable and fast convergence characteristics and has been applied to optimize the geometry of both surface-mounted and interior PMM configurations. The proposed motor is based on the thorough tradeoff among the two alternative optimized geometries and has been validated through measurements on a prototype. Autors: Athanasios G. Sarigiannidis;Minos E. Beniakar;Antonios G. Kladas; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5762 - 5774 Publisher: IEEE
» Fast and Accurate Rat Head Motion Tracking With Point Sources for Awake Brain PET
 Abstract:To avoid the confounding effects of anesthesia and immobilization stress in rat brain positron emission tomography (PET), motion tracking-based unrestrained awake rat brain imaging is being developed. In this paper, we propose a fast and accurate rat headmotion tracking method based on small PET point sources. PET point sources (3-4) attached to the rat’s head are tracked in image space using 15–32-ms time frames. Our point source tracking (PST) method was validated using a manually moved microDerenzo phantom that was simultaneously tracked with an optical tracker (OT) for comparison. The PST method was further validated in three awake [18F]FDG rat brain scans. Compared with the OT, the PST-based correction at the same frame rate (31.2 Hz) reduced the reconstructed FWHM by 0.39–0.66 mm for the different tested rod sizes of the microDerenzo phantom. The FWHM could be further reduced by another 0.07–0.13 mm when increasing the PST frame rate (66.7 Hz). Regional brain [18F]FDG uptake in the motion corrected scan was strongly correlated () with that of the anesthetized reference scan for all three cases (). The proposed PST method allowed excellent and reproducible motion correction in awake in vivo experiments. In addition, there is no need of specialized tracking equipment or additional calibrations to be performed, the point sources are practically imperceptible to the rat, and PST is ideally suitable for small bore scanners, where optical tracking might be challenging. Autors: Alan Miranda;Steven Staelens;Sigrid Stroobants;Jeroen Verhaeghe; Appeared in: IEEE Transactions on Medical Imaging Publication date: Jul 2017, volume: 36, issue:7, pages: 1573 - 1582 Publisher: IEEE
» Fast and Efficient Algorithms for Computational Electromagnetics on GPU Architecture
 Abstract:Magnetic diagnostics are essential for the operation and understanding of a magnetic confinement fusion (MCF) device, for example, by providing in real-time, the axisymmetric measurements needed for plasma equilibrium reconstructions or magnetohydrodynamic instabilities control. In this paper, we present a fast and robust implementation on GPU architecture of an accurate algorithm suitable for the computation of synthetic magnetic measurements used both in real time applications and off-line reconstruction procedures. The proposed procedure is first applied to benchmark problems, to validate the compute unified device architecture implementation, and then to cases of practical interests in MCF. Autors: Tautvydas Maceina;Paolo Bettini;Gabriele Manduchi;Mauro Passarotto; Appeared in: IEEE Transactions on Nuclear Science Publication date: Jul 2017, volume: 64, issue:7, pages: 1983 - 1987 Publisher: IEEE
» Fast and Reliable Primary Frequency Reserves From Refrigerators With Decentralized Stochastic Control
 Abstract:Due to increasing shares of renewable energy sources, more frequency reserves are required to maintain power system stability. In this paper, we present a decentralized control scheme that allows a large aggregation of refrigerators to provide Primary Frequency Control (PFC) reserves to the grid based on local frequency measurements and without communication. The control is based on stochastic switching of refrigerators depending on the frequency deviation. We develop methods to account for typical lockout constraints of compressors and increased power consumption during the startup phase. In addition, we propose a procedure to dynamically reset the thermostat temperature limits in order to provide reliable PFC reserves, as well as a corrective temperature feedback loop to build robustness to biased frequency deviations. Furthermore, we introduce an additional randomization layer in the controller to account for thermostat resolution limitations, and finally, we modify the control design to account for refrigerator door openings. Extensive simulations with actual frequency signal data and with different aggregation sizes, load characteristics, and control parameters, demonstrate that the proposed controller outperforms a relevant state-of-the-art controller. Autors: Evangelos Vrettos;Charalampos Ziras;Göran Andersson; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 2924 - 2941 Publisher: IEEE
» Fast Channel Tracking for Terahertz Beamspace Massive MIMO Systems
 Abstract:The recent concept of beamspace multiple input multiple output (MIMO) with discrete lens array can utilize beam selection to reduce the number of radio-frequency chains (RF) required in terahertz (THz) massive MIMO systems. However, to achieve the capacity-approaching performance, beam selection requires information on a beamspace channel of large size. This is difficult to obtain since the user mobility usually leads to the fast variation of THz beamspace channels, and the conventional real-time channel estimation schemes involve unaffordable pilot overhead. To solve this problem, in this paper, we propose the a priori aided (PA) channel tracking scheme. Specifically, by considering a practical user motion model, we first excavate a temporal variation law of the physical direction between the base station and each mobile user. Then, based on this law and the special sparse structure of THz beamspace channels, we propose to utilize the obtained beamspace channels in the previous time slots to predict the prior information of the beamspace channel in the following time slot without channel estimation. Finally, aided by the obtained prior information, the time-varying beamspace channels can be tracked with low pilot overhead. Simulation results verify that to achieve the same accuracy, the proposed PA channel tracking scheme requires much lower pilot overhead and signal-to-noise ratio (SNR) than the conventional schemes. Autors: Xinyu Gao;Linglong Dai;Yuan Zhang;Tian Xie;Xiaoming Dai;Zhaocheng Wang; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5689 - 5696 Publisher: IEEE
» Fast Neutron Detection Using Pixelated CdZnTe Spectrometers
 Abstract:Fast neutrons are an important signature of special nuclear materials (SNMs). They have a low natural background rate and readily penetrate high atomic number materials that easily shield gamma-ray signatures. Therefore, they provide a complementary signal to gamma rays for detecting shielded SNM. Scattering kinematics dictate that a large nucleus (such as Cd or Te) will recoil with small kinetic energy after an elastic collision with a fast neutron. Charge carrier recombination and quenching further reduce the recorded energy deposited. Thus, the energy threshold of CdZnTe detectors must be very low in order to sense the small signals from these recoils. In this paper, the threshold was reduced to less than 5 keVee to demonstrate that the 5.9-keV X-ray line from 55Fe could be separated from electronic noise. Elastic scattering neutron interactions were observed as small energy depositions (less than 20 keVee) using digitally sampled pulse waveforms from pixelated CdZnTe detectors. Characteristic gamma-ray lines from inelastic neutron scattering were also observed. Autors: Michael Streicher;David Goodman;Yuefeng Zhu;Steven Brown;Scott Kiff;Zhong He; Appeared in: IEEE Transactions on Nuclear Science Publication date: Jul 2017, volume: 64, issue:7, pages: 1920 - 1926 Publisher: IEEE
» Fast Numerical Simulation of Focused Ultrasound Treatments During Respiratory Motion With Discontinuous Motion Boundaries
 Abstract:Objective: Focused ultrasound (FUS) is rapidly gaining clinical acceptance for several target tissues in the human body. Yet, treating liver targets is not clinically applied due to a high complexity of the procedure (noninvasiveness, target motion, complex anatomy, blood cooling effects, shielding by ribs, and limited image-based monitoring). To reduce the complexity, numerical FUS simulations can be utilized for both treatment planning and execution. These use-cases demand highly accurate and computationally efficient simulations. Methods: We propose a numerical method for the simulation of abdominal FUS treatments during respiratory motion of the organs and target. Especially, a novel approach is proposed to simulate the heating during motion by solving Pennes’ bioheat equation in a computational reference space, i.e., the equation is mathematically transformed to the reference. The approach allows for motion discontinuities, e.g., the sliding of the liver along the abdominal wall. Results: Implementing the solver completely on the graphics processing unit and combining it with an atlas-based ultrasound simulation approach yields a simulation performance faster than real time (less than 50-s computing time for 100 s of treatment time) on a modern off-the-shelf laptop. The simulation method is incorporated into a treatment planning demonstration application that allows to simulate real patient cases including respiratory motion. Conclusion: The high performance of the presented simulation method opens the door to clinical applications. Significance:The methods bear the potential to enable the application of FUS for moving organs. Autors: Michael Schwenke;Joachim Georgii;Tobias Preusser; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Jul 2017, volume: 64, issue:7, pages: 1455 - 1468 Publisher: IEEE
» Fast Plane Wave 2-D Vector Flow Imaging Using Transverse Oscillation and Directional Beamforming
 Abstract:Several techniques can estimate the 2-D velocity vector in ultrasound. Directional beamforming (DB) estimates blood flow velocities with a higher precision and accuracy than transverse oscillation (TO), but at the cost of a high beamforming load when estimating the flow angle. In this paper, it is proposed to use TO to estimate an initial flow angle, which is then refined in a DB step. Velocity magnitude is estimated along the flow direction using cross correlation. It is shown that the suggested TO-DB method can improve the performance of velocity estimates compared with TO, and with a beamforming load, which is 4.6 times larger than for TO and seven times smaller than for conventional DB. Steered plane wave transmissions are employed for high frame rate imaging, and parabolic flow with a peak velocity of 0.5 m/s is simulated in straight vessels at beam-to-flow angles from 45° to 90°. The TO-DB method estimates the angle with a bias and standard deviation (SD) less than 2°, and the SD of the velocity magnitude is less than 2%. When using only TO, the SD of the angle ranges from 2° to 17° and for the velocity magnitude up to 7%. Bias of the velocity magnitude is within 2% for TO and slightly larger but within 4% for TO-DB. The same trends are observed in measurements although with a slightly larger bias. Simulations of realistic flow in a carotid bifurcation model provide visualization of complex flow, and the spread of velocity magnitude estimates is 7.1 cm/s for TO-DB, while it is 11.8 cm/s using only TO. However, velocities for TO-DB are underestimated at peak systole as indicated by a regression value of 0.97 for TO and 0.85 for TO-DB. An in vivo scanning of the carotid bifurcation is used for vector velocity estimations using TO and TO-DB. The SD of the velocity profile over - cardiac cycle is 4.2% for TO and 3.2% for TO-DB. Autors: Jonas Jensen;Carlos Armando Villagómez Hoyos;Matthias Bo Stuart;Caroline Ewertsen;Michael Bachmann Nielsen;Jørgen Arendt Jensen; Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control Publication date: Jul 2017, volume: 64, issue:7, pages: 1050 - 1062 Publisher: IEEE
» Fast Terminal Sliding-Mode Control With an Integral Filter Applied to a Van Der Pol Oscillator
 Abstract:This paper proposes a procedure for designing a fast terminal sliding-mode control involving an integral filter that guarantees a finite time of convergence to zero dynamics, robustness against polynomial bounded uncertainties, and external disturbances. It reduces the chattering effect by employing a state-dependent gain and adds an integral filter to smooth the input control signal. We suggest a simplified algorithm to design the controller. To test the performance of the algorithm, we use a Van der Pol chaotic oscillator synchronization with perturbations in the states. Finally, we compare the performance of the method by using the proposed controller with the filter turned-on and turned-off. Autors: Cesar U. Solis;Julio B. Clempner;Alexander S. Poznyak; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Jul 2017, volume: 64, issue:7, pages: 5622 - 5628 Publisher: IEEE
» Fault Current Detection and Dangerous Voltages in DC Urban Rail Traction Systems
 Abstract:In this paper, the electrical safety of dc urban traction systems is analyzed, with particular focus on fault current detection and on dangerous voltages which could arise in case of fault. For the discussion, the tram network of Turin, Italy, is used as a case study. First, the structure of the dc traction power supply is described, analyzing in detail the different components; then, the safety of the system is analyzed, examining possible types of fault. In particular, ground faults inside the substation and ground faults along the line are analyzed in detail. Fault currents and dangerous voltages are calculated, thanks to a simplified steady-state circuital model of the traction system. Finally, the consequent risks for the people are examined and some conclusions and possible solutions are presented. Autors: Enrico Pons;Riccardo Tommasini;Pietro Colella; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 4109 - 4115 Publisher: IEEE
» Feasibility Assessments and Designs of a Hybrid Suspension System for Motorbike Application
 Abstract:To effectively retrieve the inherent vibration energies, feasibility of replacing those common mechanical shock absorbers of the suspension system that are mounted between the wheels and bogie of a motorbike with electromagnetic motion device will be assessed. Instead of consuming additional energies to control the vibration patterns, the main design objectives are to produce the su-spension forces to meet the maximum encountered force specifications and to convert the input mechanical vibrations to electric energies directly. Based on proper emulation designs and electrical output controls, the operational fluxes and dynamic characteristics of this hybrid suspension system at various operational conditions will be thoroughly investigated, and the satisfactory performances of the proposed system can then be systematically validated. Autors: Cheng-Tsung Liu;Wei-Ping Lin;Chi-Yin Hung;Chang-Chou Hwang; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3420 - 3427 Publisher: IEEE
» Feature Fusion for Prediction of Theaflavin and Thearubigin in Tea Using Electronic Tongue
 Abstract:Liquor characteristics of black cut, tear, and curl tea mostly depend on two biochemical components like theaflavin (TF) and thearubigin (TR). Evaluation of tea quality can be done efficiently by estimating the concentration of TF and TR without using biochemical tests as it takes much time, which requires laborious effort for sample preparation, storage, and measurement. Moreover, the required instruments for this test are very costly. In this paper, we have proposed an efficient method of TF and TR prediction in a given tea sample using electronic tongue (ET) signal. Combinations of transformed features, like discrete cosine transform, Stockwell transform (ST), and singular value decomposition, of ET signals are fused to develop regression models to predict the contents of TF, TR, and TR/TF. Three different regression models such as artificial neural network, vector-valued regularized kernel function approximation, and support vector regression are used to evaluate the performance of the proposed method. High prediction accuracy using fusion of features ensures the effectiveness of the proposed method for prediction of TF and TR using ET signals. Autors: Pradip Saha;Santanu Ghorai;Bipan Tudu;Rajib Bandyopadhyay;Nabarun Bhattacharyya; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Jul 2017, volume: 66, issue:7, pages: 1703 - 1710 Publisher: IEEE
» Femtosecond Resolution Timing in Multi-GS/s Waveform Digitizing ASICs
 Abstract:A waveform digitizer with high-resolution timing provides with the possibility of a novel approach to vertex detectors for high-luminosity particle colliders. Present efforts are centered on the development of an application specific integrated circuit (ASIC) intended to measure signal arrival times with timing resolution in the range of 100 fs or less. The design of such an ASIC requires very good understanding of the effects that impact the timing resolution. This paper presents the simulation results that clearly identify and quantify the sources of error and the underlying coupling mechanisms. In addition, a synthetic waveform generator, developed solely for this purpose, is presented and validated through the measurement results. Crucial knowledge, insights, and confidence have been gained for the development of the ASIC or any other fast, wideband RF systems that aim to achieve such performance. Autors: Peter Orel;Gary S. Varner; Appeared in: IEEE Transactions on Nuclear Science Publication date: Jul 2017, volume: 64, issue:7, pages: 1950 - 1962 Publisher: IEEE
» FETs on 2-D Materials: Deconvolution of the Channel and Contact Characteristics by Four-Terminal Resistance Measurements on WSe2 Transistors
 Abstract:FETs made on 2-D semiconductors, typically without degenerate doping at the contacts, have a significant Schottky junction (SJ) resistance, which complicates transistor analysis. This paper evaluates the effect of the contact resistance on the 2-D-material FET characteristics through four-terminal (4-T) resistance measurements on WSe2 FETs, which allow studying the channel and contacts characteristics separately. Apart from showing the nonnegligibility of contact resistance, this paper enables a finer understanding of commonly observed phenomena, such as transistor performance improvement with dielectric-encapsulation is observed to have a stronger effect on the contact than the channel; the resistance of the forward-biased SJ is observed to be not negligible, but comparable to that of the reverse-biased junction; at biases commonly referred to as “low-bias,” the WSe2 FET resistance could be dominated by the contacts; and pinchoff can be observed at relatively lower current levels, being related to the channel-contact resistance ratio rather than their magnitudes. In the devices where true channel pinchoff can be verified, a correlation emerges between current saturating behavior and asymmetry in the output characteristics with respect to the drain–source bias polarity, a feature that may serve as a guide toward interpreting standard FET output characteristics in 2-D materials. Autors: Surajit Sutar;Inge Asselberghs;Dennis H. C. Lin;Aaron Voon-Yew Thean;Iuliana Radu; Appeared in: IEEE Transactions on Electron Devices Publication date: Jul 2017, volume: 64, issue:7, pages: 2970 - 2976 Publisher: IEEE
» Fiber-Coupled 2-D n-i-pn-i-p Superlattice Photomixer Array
 Abstract:We have fiber-coupled an array of n-i-pn-i-p superlattice photomixers using a fiber array of same pitch of 145 . We experimentally investigate the effect of the finite size of the implemented silicon lens on the interference between the array elements in the far field. We compare the results from a geometry optimized for a collimated terahertz (THz) beam to theory and simulations. Further, beam steering is demonstrated by controlling the optical phase of the individual photomixers. Due to broadband antennas attached to each array element, the array is frequency tunable. It is exemplarily characterized at 165 and 310 GHz. Such arrays can overcome power limitations of individual photomixers. In contrast to bulky individually packaged free space solutions, this array can be packaged to a compact terahertz source, limited in size only by the size of the silicon lens. The investigated array features a spot diameter (full-width at half-maximum) of 12.1 mm at a distance of 19 cm at 310 GHz with a silicon lens of only 20-mm diameter. Autors: Sascha Preu;Christian Müller-Landau;Stefan Malzer;Gottfried H. Döhler;Hong Lu;Arthur C. Gossard;Daniel Segovia-Vargas;Alejandro Rivera-Lavado;L. Enrique Garcia-Muñoz; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Jul 2017, volume: 65, issue:7, pages: 3474 - 3480 Publisher: IEEE
» Figure of Merit of All-Dielectric Waveguide Structures for Absorption Overtone Spectroscopy
 Abstract:The figure of merit is proposed for all-dielectric waveguides for absorption overtone spectroscopy as the measure of probing efficiency of molecular overtones. It is defined as the power in the evanescent tail over the total power carried by the guided mode. The figure of merit was calculated for the proposed waveguide structures and then compared. We address each waveguide structure in probing overtones. We show that the figure of merit can be substantially increased due to the downscaling of the physical dimensions of the waveguide and microfiber. Such a configuration enables integration possibilities for ultrasensitive devices harnessing evanescent excitation of molecular overtones on miniature and portable chips. Autors: Aviad Katiyi;Alina Karabchevsky; Appeared in: Journal of Lightwave Technology Publication date: Jul 2017, volume: 35, issue:14, pages: 2902 - 2908 Publisher: IEEE
» Finding Propagation Constants of Leaky and Degenerate Modes Using Simultaneous Transcendental Equations of Holey Optical Fibers
 Abstract:This paper presents a simple solution to simultaneous transcendental equations of propagation constants for leaky and degenerate modes. Using a block version of the Sakurai-Sugiura method (SSM) and a criterion for distinguishing physical solutions from spurious ones, we solved a nonlinear matrix equation formulated by the multipole method in a two-dimensional cylindrical coordinate system. Numerical examples showed that we can obtain accurate propagation constants and extract field distributions of leaky and degenerate modes of holey fibers without imposing symmetry. In addition, the condition numbers of the eigenvalues are efficient criteria for distinguishing solutions computed by the block version of the SSM. Autors: Shingo Sato;Koji Hasegawa;Yasuo Tsushima; Appeared in: Journal of Lightwave Technology Publication date: Jul 2017, volume: 35, issue:14, pages: 2871 - 2879 Publisher: IEEE
» Fine-Grained Vehicle Model Recognition Using A Coarse-to-Fine Convolutional Neural Network Architecture
 Abstract:Fine-grained vehicle model recognition is a challenging problem in intelligent transportation systems due to the subtle intra-category appearance variation. In this paper, we demonstrate that this problem can be addressed by locating discriminative parts, where the most significant appearance variation appears, based on the large-scale training set. We also propose a corresponding coarse-to-fine method to achieve this, in which these discriminative regions are detected automatically based on feature maps extracted by convolutional neural network. A mapping from feature maps to the input image is established to locate the regions, and these regions are repeatedly refined until there are no more qualified ones. The global and local features are then extracted from the whole vehicle images and the detected regions, respectively. Based upon the holistic cues and the subordinate-level variation within these global and local features, an one-versus-all support vector machine classifier is applied for classification. The experimental results show that our framework outperforms most of the state-of-the-art approaches, achieving 98.29% accuracy over 281 vehicle makes and models. Autors: Jie Fang;Yu Zhou;Yao Yu;Sidan Du; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Jul 2017, volume: 18, issue:7, pages: 1782 - 1792 Publisher: IEEE
» Finite Element Method for Resonant Cavity Problem With Complex Geometrical Structure and Anisotropic Fully Conducting Media
 Abstract:In this paper, the resonant cavity problem with anisotropic fully conducting media, complex geometrical structure and perfect electric conductor walls is investigated. We solve this problem based on the finite element method (FEM) with tangential and linear normal (CT/LN) element and standard linear element. An effective numerical method is proposed by us such that it is free of nonphysical modes. After the FEM discretization, we need to solve a quadratic algebraic eigenvalue problem with a linear constraint condition. In order to overcome this difficulty in the field of numerical algebra, we change this algebraic eigenvalue problem into a generalized eigenvalue problem by introducing an auxiliary zero eigenvector. Moreover, when the permittivity and conductivity are two constants, both the eigenmodes of infinite algebraic multiplicity and all the nonphysical modes are also removed by linearization method. Several numerical experiments show that computational method in this paper can suppress all the spurious modes. Autors: Wei Jiang;Jie Liu;Xiaoping Xiong;Qing Huo Liu; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Jul 2017, volume: 65, issue:7, pages: 2240 - 2248 Publisher: IEEE
» Fixed Versus Selective Scheduling for Buffer-Aided Diamond Relay Systems Under Statistical Delay Constraints
 Abstract:In this paper, the achievable rate of buffer-aided diamond relay systems under delay constraints is studied. The effective capacity, characterizing the maximum constant arrival rate to the source while satisfying the statistical end-to-end delay constraints, is obtained for the conventional relay selection protocol, fixed decode-and-forward relaying schemes, and selective forwarding protocols. A selection forwarding policy that maximizes the delay exponent at the source is proposed, which is shown to be independent of delay constraints and select the relay with better channel conditions to forward the messages. Through numerical results, it is demonstrated that the selection forwarding strategy achieves superior performance than the conventional relay selection and fixed scheduling schemes under a variety of delay constraints. Autors: Deli Qiao; Appeared in: IEEE Transactions on Communications Publication date: Jul 2017, volume: 65, issue:7, pages: 2838 - 2851 Publisher: IEEE
» Flexible Ammonia Sensor Based on PEDOT:PSS/Silver Nanowire Composite Film for Meat Freshness Monitoring
 Abstract:Flexible ammonia (NH3) sensors were fabricated on polyethylene terephthalate substrate using poly(3, 4-ethylene-dioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)/silver nanowire (AgNW) composite film as the active layer. With the AgNWs of optimized concentration being incorporated into the PEDOT:PSS film, the sensitivity of the devices was significantly improved. Even with simple digitally dispensed parallel structure electrodes, the device achieved excellent sensing performance, and was shown to be able to detect very low NH3 concentration below 500 ppb. The mechanism for the sensing performance improvement was revealed. The sensor also showed considerable selectivity with respect to water and common organic vapors. Finally, the sensor was integrated with a self-designed portable data acquisition system to monitor the freshness of pork, demonstrating its feasibility for inspecting the meat quality in the early stage. Autors: Siying Li;Sujie Chen;Bengang Zhuo;Qiaofeng Li;Wenjiang Liu;Xiaojun Guo; Appeared in: IEEE Electron Device Letters Publication date: Jul 2017, volume: 38, issue:7, pages: 975 - 978 Publisher: IEEE
» Flexible Lactate and Glucose Sensors Using Electrolyte-Gated Carbon Nanotube Field Effect Transistor for Non-Invasive Real-Time Monitoring
 Abstract:We demonstrate flexible, low cost glucose and lactate sensors using novel enzyme immobilization scheme, primarily aimed toward wearable devices. The intrinsic chemical nature of polyimide films is harnessed to immobilize the enzyme on the polyimide substrate using a dicarboxylic acid. Sensors are fabricated using carbon nanotube as an active channel material. Minimum degradation of the transistor performance is seen after enzyme immobilization. The lowest concentration that can be resolved effectively is in pM range. The sensors demonstrate good sensing ability in the physiological range for wearable and implantable devices. The sensors were re-measured after three weeks and still retain their sensing ability with some decrease in the sensitivity. They also demonstrate good endurance against mechanical deformations. Autors: Saumya Joshi;Vijay Deep Bhatt;Hao Wu;Markus Becherer;Paolo Lugli; Appeared in: IEEE Sensors Journal Publication date: Jul 2017, volume: 17, issue:14, pages: 4315 - 4321 Publisher: IEEE
» FlexLevel NAND Flash Storage System Design to Reduce LDPC Latency
 Abstract:Aggressive technology scaling and adoption of multilevel-cell technique lead to progressive increase of bit error rate (BER) of NAND flash memory. Consequently, conventional error correction code is not adequate to guarantee system reliability. As an alternative, low density parity check (LDPC) code is introduced to provide more powerful error correction capability. However, to achieve better performance, LDPC code demands extra memory sensing operations and more data transfer cycles, directly leading to longer read latency. To achieve both system reliability and read efficiency, we propose the FlexLevel NAND flash storage system design in this paper. FlexLevel consists of two levels of optimization: 1) LevelAdjust and 2) AccessEval. At device level, the LevelAdjust technique is proposed to reduce BER by broadening noise margin via threshold voltage level reduction. With LevelAdjust, BER is greatly reduced and no extra sensing levels are required to protect data integrity. Hence, read performance is improved. However, while LevelAdjust can improve system reliability and read performance, it causes density loss. To balance read performance improvement and density loss, we propose the AccessEval technique at system level. AccessEval identifies data with high LDPC overhead and only applies LevelAdjust technique to these data. The experimental results show that compared with the best existing works, the proposed design can achieve up to 11% read speedup with negligible density loss. Autors: Jie Guo;Wujie Wen;Jingtong Hu;Danghui Wang;Hai Li;Yiran Chen; Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems Publication date: Jul 2017, volume: 36, issue:7, pages: 1167 - 1180 Publisher: IEEE
» FlexRay and Ethernet AVB Synchronization for High QoS Automotive Gateway
 Abstract:Modern in-vehicle networks are comprised of heterogeneous systems that use various communication protocols with different source clocks. Moreover, gateway systems are designed with additional features that ensure converted/forwarded data meet real-time constraints. In this paper, we propose a synchronization mechanism for FlexRay and Ethernet audio video bridging (AVB) network that guarantees a high quality-of-service. We also designed the corresponding embedded system based-gateway system. Moreover, we built an in-vehicle network environment that consists of FlexRay and Ethernet AVB networks using an embedded system, which is integrated and synchronized by the gateway. We evaluate the synchronization performance of the proposed method using the developed gateway by conducting experiments as well as a theoretical analysis. The results of the experiment show that the synchronization mechanism provides timing guarantees for the FlexRay network that are similar to those of the Ethernet AVB network. Autors: Young Seo Lee;Jin Ho Kim;Jae Wook Jeon; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5737 - 5751 Publisher: IEEE
» Flyback-Based Three-Port Topologies for Electrolytic Capacitor-Less LED Drivers
 Abstract:Electrolytic capacitors are the components that mainly impact the lifetime of ac/dc light-emitting diode (LED) drivers. Therefore, eliminating electrolytic capacitors from LED drivers is of vital importance. First, the basic derivation concept of a family of flyback-based three-port converters for electrolytic capacitor-less LED drivers is addressed in this paper, by manipulating the power flow among input port, output port, and storage capacitors. Together with the derivation of existing topologies, new topologies are also proposed. After evaluation, an integrated dual flyback converter (IDFC) is chosen, which requires less switching components and simpler control strategy. Following that, the operation principle and switching modes of the IDFC are elaborated, as well as the parameter design and implementation of control strategy. Finally, experiments on a laboratory prototype are carried out to verify the feasibility of the proposed topology. Autors: Fei Wang;Lin Li;Yuanxu Zhong;Xinyi Shu; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Jul 2017, volume: 64, issue:7, pages: 5818 - 5827 Publisher: IEEE
» Flywheel Energy Storage Model, Control and Location for Improving Stability: The Chilean Case
 Abstract:A flywheel energy storage (FES) plant model based on permanent magnet machines is proposed for electro-mechanical analysis. The model considers parallel arrays of FES units and describes the dynamics of flywheel motion, dc-link capacitor, and controllers. Both unit and plant-level controllers are considered. A 50-MW FES plant model is tested in the Northern Chile Interconnected System (NCIS) when connected to the Argentinian Interconnected System (AIS). The FES plant provides transient support for primary frequency regulation and its impact on stability is studied using small-signal analysis and time domain simulations. To identify the best location to install the FES plant, eigenvalue sensitivity for the interarea mode is analyzed. The results are validated for different operation scenarios of wind and solar power. By installing the FES plant in the NCIS best location, the damping ratio of the interarea mode is increased from 0.53% to 13.1%. Moreover, the power transfer from the NCIS to the AIS can be augmented from 90 to 180 MW while still keeping the damping ratio above 9%. These findings are promising and may lead to useful planning criteria for energy storage deployment. Autors: Horacio Silva-Saravia;Héctor Pulgar-Painemal;Juan Manuel Mauricio; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3111 - 3119 Publisher: IEEE
» Focus-Plus-Context Techniques for Picoprojection-Based Interaction
 Abstract:In this paper, we report on novel zooming interface methods that deploy a small handheld projector. Using mobile projections to visualize object/environment-related information on real objects introduces new aspects for zooming interfaces. Different approaches are investigated that focus on maintaining a level of context while exploring detailed information. Doing so, we propose methods that provide alternative contextual cues within a single projector and deploy the potential of zoom lenses to support a multilevel zooming approach. Furthermore, we look into the correlation between pixel density, distance to the target, and projection size. Alongside these techniques, we report on multiple user studies, in which we quantified the projection limitations and validated various interactive visualization approaches. Thereby, we focused on solving issues related to pixel density, brightness, and contrast that affect the design of more effective legible zooming interfaces for handheld projectors. Autors: Jens Maiero;Ernst Kruijff;André Hinkenjann;Gheorghita Ghinea; Appeared in: IEEE Transactions on Multimedia Publication date: Jul 2017, volume: 19, issue:7, pages: 1521 - 1530 Publisher: IEEE
» Formation of Winter Supertyphoons Haiyan (2013) and Hagupit (2014) Through Interactions With Cold Fronts as Observed by Multifunctional Transport Satellite
 Abstract:This paper incorporates remote sensing imagery and image processing techniques to analyze typhoons’ evolution into supertyphoons through interactions with cold fronts in the Western Pacific Ocean. The purpose is to enhance understanding and predictability of the tracks and profiles of supertyphoons. Evolutions of typhoons Haiyan (2013) and Hagupit (2014) into supertyphoons were studied. The 3-D profiles of weather systems were reconstructed using multifunctional transport satellite IR cloud images. When interactions between typhoon and cold front happened, enhancements of typhoons were observed causing typhoons Haiyan and Hagupit to strengthen power and evolve into supertyphoons. The origins of typhoons Haiyan and Hagupit are closely located at 152°50E/05°12N and 151°30E/04°19N, respectively. Both typhoons went through The Philippine Sea in the zone of 112°52E–146°11E. The lowest values of central pressures of typhoons Haiyan and Hagupit occurred along their paths at the positions 128°41E/10°16N and 131°06E/11°00N, respectively. Their distances from cold front and average speed of their movement were dominating parameters for the formation of winter supertyphoons. The supertyphoon Haiyan showed higher intensity than the supertyphoon Hagupit. Each of the two typhoons roughly consisted of two paths with the first path moving westerly and the second path northerly. The two typhoons evolved into supertyphoons at the turning points of the two paths. The first paths were about 2330 and 2050 km for typhoons Haiyan and Hagupit, respectively. Autors: Yung-Sheng Lee;Yuei-An Liou;Ji-Chyun Liu;Ching-Tsan Chiang;Kuan-Dih Yeh; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Jul 2017, volume: 55, issue:7, pages: 3800 - 3809 Publisher: IEEE
» FoToNoC: A Folded Torus-Like Network-on-Chip Based Many-Core Systems-on-Chip in the Dark Silicon Era
 Abstract:Dark silicon refers to the phenomenon that a fraction of a many-core chip has to become “dark” or “dim” in order to guarantee the system to be kept in a safe temperature range and allowable power budget. Techniques have been developed to selectively activate non-adjacent cores on many-core chip to avoid temperature hotspot, while resulting unexpected increase of communication overhead due to the longer average distance between active cores, and in turn affecting application performance and energy efficiency, when Network-on-Chip (NoC) is used as a scalable communication subsystem. To address the brand-new challenges brought by dark silicon, in this paper, we present FoToNoC, a Folded Torus-like NoC, coupled with a hierarchical management strategy for heterogeneous many-core systems. On top of it, objectives of maximizing application performance, energy efficiency and chip reliability are isolated and well achieved by hardware-software co-design in several different phases, including application mapping and scheduling, cluster management and DVFS control. Evaluations on PARSEC benchmark applications demonstrate the significance of the entire strategy. Compared with state-of-the-art approaches, the proposed FoToNoC organization can achieve on average 35.4 and 35.2 percent on communication efficiency and application performance improvement, respectively, when maintaining the safe chip temperature. The hierarchical cluster-based management strategy can further reduce an average 34.6 percent of the total energy consumption with a notable reduction on the chip peak temperature. The significant achievements on system energy efficiency and the reduction on chip temperature of H.264 decoder and DSP-stone benchmarks additionally verify the effectiveness of the proposed methods. Autors: Lei Yang;Weichen Liu;Weiwen Jiang;Mengquan Li;Peng Chen;Edwin Hsing-Mean Sha; Appeared in: IEEE Transactions on Parallel and Distributed Systems Publication date: Jul 2017, volume: 28, issue:7, pages: 1905 - 1918 Publisher: IEEE
» Fractal Analysis of Positive Streamer Patterns in Transformer Oil-Based TiO2 Nanofluid
 Abstract:In this paper, prebreakdown streamers in transformer oil and transformer oil-based TiO2 nanofluid were observed by the schlieren method under positive lightning impulse voltage. Streamers in the nanofluid have numerous branches with much shorter length, whereas in the pure oil, they exhibit only certain filaments with longer length. The discrepancy in positive streamer pattern of both oils is further investigated under a range of applied voltages. The complexity of streamer patterns was quantitatively described using the fractal analysis method. Results indicate that the fractal dimension of streamer patterns shows different changing tendencies in both oils, and it keeps higher value in the nanofluid than that in pure oil during the whole propagation process, well corresponding with streamer propagating structures. Moreover, a new parameter, the ratio of fractal dimension to propagation length (D/L), is introduced to classify the complex streamer patterns for the first time. Three propagation zones in both nanofluid and pure oil are clearly categorized by the value of D/L, providing a quantitative way to distinguish the streamer patterns. Autors: Yuzhen Lv;Yang Ge;Qian Du;Qian Sun;Bingliang Shan;Meng Huang;Chengrong Li;Bo Qi;Jinsha Yuan; Appeared in: IEEE Transactions on Plasma Science Publication date: Jul 2017, volume: 45, issue:7, pages: 1704 - 1709 Publisher: IEEE
» Frequency Striations Induced by Moving Nonlinear Internal Waves and Applications
 Abstract:Modal interferences are evident in the spectrogram of broadband signals propagated over distances and received on a single receiver. Plotted against range and frequency, the spectrogram displays striated bands of constant acoustic intensity levels as explained by the waveguide-invariant theory, the slope of which can be used to estimate the source range by the waveguide-invariant parameter “beta.” Given a vertical array of receivers, one finds, however, no frequency striation in the depth-integrated acoustic energy, as the total energy corrected for geometrical spreading remains “conserved” except for mode attenuations. When nonlinear solitary internal waves (SIWs) are present in the propagation path, one finds a different phenomenon: the depth-integrated energy will display striations with respect to time and frequency. In this case, the striation slope is related to the source-to-SIW range, and not the source–receiver range. The striation is caused predominantly by mode coupling (as opposed to mode interference), which changes the mode amplitudes as the SIWs move. Theory and simulations are developed in this paper. As an application, one can use the SIW-induced striations to monitor the positions (and wavefronts) of nonlinear internal waves on a continuous time basis. This method is evaluated using the SWARM95 experimental environment to address the real-world issues. Autors: T. C. Yang;Chen-Fen Huang;S. H. Huang;Jin-Yuan Liu; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Jul 2017, volume: 42, issue:3, pages: 663 - 671 Publisher: IEEE
» Frequency-Domain Turbo Equalization With Iterative Channel Estimation for MIMO Underwater Acoustic Communications
 Abstract:This paper proposes a new iterative receiver for single-carrier multiple-input–multiple-output (SC-MIMO) underwater acoustic (UWA) communications, which utilizes frequency-domain turbo equalization (FDTE) and iterative channel estimation. Soft-decision symbols are not only fed back to the equalizer to cancel the intersymbol interference (ISI) and cochannel interference (CCI), but also used as training signals in the channel estimator to update the estimated channel state information (CSI) after each turbo iteration. This iterative channel estimation scheme helps to combat the problem commonly suffered by block-processing receivers in fast time-varying channels. Compared with time-domain turbo equalization, FDTE achieves comparable performance with significantly reduced computational complexity. Using soft-decision symbols to reestimate the time-varying channels, iterative channel estimation further improves the accuracy of the estimated CSI. The proposed iterative receiver has been verified through undersea experimental data collected in the Surface Processes and Acoustic Communications Experiment 2008 (SPACE08). Autors: Zhenrui Chen;Jintao Wang;Yahong Rosa Zheng; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Jul 2017, volume: 42, issue:3, pages: 711 - 721 Publisher: IEEE
» Frequency-Modulation Control of a DC/DC Current-Source Parallel-Resonant Converter
 Abstract:This paper proposes a frequency-modulation control scheme for a dc/dc current-source parallel-resonant converter with two possible configurations. The basic configuration comprises an external voltage loop, an internal current loop, and a frequency modulator: the voltage loop is responsible for regulating the output voltage, the current loop makes the system controllable and limits the input current, and the modulator provides robustness against variations in resonant component values. The enhanced configuration introduces the output inductor current as a feed-forward term and clearly improves the transient response to fast load changes. The theoretical design of these control schemes is performed systematically by first deriving their small-signal models and second using Bode diagram analysis. The actual performance of the proposed control schemes is experimentally validated by testing on a laboratory prototype. Autors: Mohammad Moradi Ghahderijani;Miguel Castilla;Arash Momeneh;Jaume Tomas Miret;Luis Garcia de Vicuña; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Jul 2017, volume: 64, issue:7, pages: 5392 - 5402 Publisher: IEEE
» Full-Duplex Backscatter Interference Networks Based on Time-Hopping Spread Spectrum
 Abstract:Future Internet-of-Things (IoT) is expected to wirelessly connect billions of low-complexity devices. For wireless information transfer (IT) in IoT, high density of IoT devices and their ad hoc communication result in strong interference, which acts as a bottleneck on wireless IT. Furthermore, battery replacement for the massive number of IoT devices is difficult if not infeasible, making wireless energy transfer (ET) desirable. This motivates: 1) the design of full-duplex wireless IT to reduce latency and enable efficient spectrum utilization and 2) the implementation of passive IoT devices using backscatter antennas that enable wireless ET from one device (reader) to another (tag). However, the resultant increase in the density of simultaneous links exacerbates the interference issue. This issue is addressed in this paper by proposing the design of full-duplex backscatter communication (BackCom) networks, where a novel multiple-access scheme based on time-hopping spread-spectrum is designed to enable both one-way wireless ET and two-way wireless IT in coexisting backscatter reader-tag links. Comprehensive performance analysis of BackCom networks is presented in this paper, including forward/backward bit-error rates and wireless ET efficiency and outage probabilities, which accounts for energy harvesting at tags, non-coherent and coherent detection at tags and readers, respectively, and the effects of asynchronous transmissions. Autors: Wanchun Liu;Kaibin Huang;Xiangyun Zhou;Salman Durrani; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4361 - 4377 Publisher: IEEE
» Full-Vector Finite-Element Beam Propagation Method for Helicoidal Waveguides and Its Application to Twisted Photonic Crystal Fibers
 Abstract:A full-vector beam propagation method based on a finite-element scheme for a helicoidal system is developed. The permittivity and permeability tensors of a straight waveguide are replaced with equivalent ones for a helicoidal system, obtained by transformation optics. A cylindrical, perfectly matched layer is implemented for the absorbing boundary condition. To treat wide-angle beam propagation, a second-order differentiation term with respect to the propagation direction is directly discretized without using a conventional Padé approximation. The transmission spectra of twisted photonic crystal fibers are thoroughly investigated, and it is found that the diameters of the air holes greatly affect the spectra. The calculated results are in good agreement with the recently reported measured results, showing the validity and usefulness of the method developed here. Autors: Takeshi Fujisawa;Takanori Sato;Kunimasa Saitoh; Appeared in: Journal of Lightwave Technology Publication date: Jul 2017, volume: 35, issue:14, pages: 2894 - 2901 Publisher: IEEE
» Fully Planar 4H-SiC Avalanche Photodiode With Low Breakdown Voltage
 Abstract:We report on the structure and performance of 4H-SiC p+-n APDs fabricated in a fully planar technology. A dark current density lower than 10 nA/cm2 at 30-V reverse bias and a breakdown voltage of 88 V were observed. A gain as high as 105 was measured at 94-V reverse bias, confirming the avalanche multiplication working condition. The maximum responsivity value was measured at 270 nm, increasing from 0.06 A/W (QE = 29%) at 0-V bias to 0.10 A/W (QE of about 45%) at 30-V reverse bias. Autors: A. Sciuto;M. Mazzillo;P. Lenzi;S. Di Franco;D. Mello;P. P. Barbarino;G. Longo;S. Cascino;A. Santangelo;S. Albergo;A. Tricomi;O. Starodubtsev;O. Adriani;G. D’Arrigo; Appeared in: IEEE Sensors Journal Publication date: Jul 2017, volume: 17, issue:14, pages: 4460 - 4465 Publisher: IEEE
» Fusion of Landsat 8 OLI and Sentinel-2 MSI Data
 Abstract:Sentinel-2 is a wide-swath and fine spatial resolution satellite imaging mission designed for data continuity and enhancement of the Landsat and other missions. The Sentinel-2 data are freely available at the global scale, and have similar wavelengths and the same geographic coordinate system as the Landsat data, which provides an excellent opportunity to fuse these two types of satellite sensor data together. In this paper, a new approach is presented for the fusion of Landsat 8 Operational Land Imager and Sentinel-2 Multispectral Imager data to coordinate their spatial resolutions for continuous global monitoring. The 30 m spatial resolution Landsat 8 bands are downscaled to 10 m using available 10 m Sentinel-2 bands. To account for the land-cover/land-use (LCLU) changes that may have occurred between the Landsat 8 and Sentinel-2 images, the Landsat 8 panchromatic (PAN) band was also incorporated in the fusion process. The experimental results showed that the proposed approach is effective for fusing Landsat 8 with Sentinel-2 data, and the use of the PAN band can decrease the errors introduced by LCLU changes. By fusion of Landsat 8 and Sentinel-2 data, more frequent observations can be produced for continuous monitoring (this is particularly valuable for areas that can be covered easily by clouds, thereby, contaminating some Landsat or Sentinel-2 observations), and the observations are at a consistent fine spatial resolution of 10 m. The products have great potential for timely monitoring of rapid changes. Autors: Qunming Wang;George Alan Blackburn;Alex O. Onojeghuo;Jadunandan Dash;Lingquan Zhou;Yihang Zhang;Peter M. Atkinson; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Jul 2017, volume: 55, issue:7, pages: 3885 - 3899 Publisher: IEEE
» Fusion of Perception and V2P Communication Systems for the Safety of Vulnerable Road Users
 Abstract:With cooperative intelligent transportation systems, vulnerable road users (VRU) safety can be enhanced by multiple means. On the one hand, perception systems are based on embedded sensors to protect VRUs. However, such systems may fail due to the sensors’ visibility conditions and imprecision. On the other hand, vehicle-to-pedestrian (V2P) communication can contribute to the VRU safety by allowing vehicles and pedestrians to exchange information. This solution is, however, largely affected by the reliability of the exchanged information, which most generally is the GPS data. Since perception and communication have complementary features, we can expect that a fusion between these two approaches can be a solution to the VRU safety. In this paper, we propose a cooperative system that combines the outputs of communication and perception. After introducing theoretical models of both individual approaches, we develop a probabilistic association between perception and V2P communication information by means of multi-hypothesis tracking. Experimental studies are conducted to demonstrate the applicability of this approach in real-world environments. Our results show that the cooperative VRU protection system can benefit of the redundancy coming from the perception and communication technologies both in line-of-sight (LOS) and non-LOS conditions. We establish that the performances of this system are influenced by the classification performances of the perception system and by the accuracy of the GPS positioning transmitted by the communication system. Autors: Pierre Merdrignac;Oyunchimeg Shagdar;Fawzi Nashashibi; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Jul 2017, volume: 18, issue:7, pages: 1740 - 1751 Publisher: IEEE
» Gain-Assisted Surface Plasmon Resonance Refractive Index Sensor
 Abstract:Surface plasmon resonance (SPR) has been a topic of intense research in refractive index sensors due to the benefits of high resolution, high sensitive, real-time, and label-free technology. But losses restrict the operational parameters of SPR-based devices. In this paper, a new design of SPR sensor structures using gain medium are proposed. These novel prisms-based structures are based on Otto and Kretschmann configurations. Regard to gain coefficient of an active layer, two different regimes have been introduced in which loss compensating and amplifying surface plasmons polaritons are occurred. The effect of geometrical parameters on SNR enhancement factor is investigated theoretically and finally, the optimum layers’ thicknesses for the fixed values of gain coefficient and wavelength will be examined. Signal-to-noise ratio in the proposed structures could be enhanced by a factor of two orders of magnitudes. Autors: Ayda Aray;Hossein Saghafifar;Hamidreza Fallah;Mahmood Soltanolkotabi; Appeared in: IEEE Sensors Journal Publication date: Jul 2017, volume: 17, issue:14, pages: 4466 - 4471 Publisher: IEEE
» Game Theoretic Analysis of Green Spectrum and Infrastructure Leasing on TV Bands
 Abstract:In this paper, we propose a green spectrum and infrastructure leasing framework for sharing unused TV spectrum, in which the ownership of the network infrastructure and spectrum are decoupled, and each can be leased as a service on demand. An incumbent TV spectrum owner (TSO) can lease a share of the infrastructure from a network infrastructure owner (NIO) with a pay-per-use model, to provide new services to its end users. On the other hand, a TSO can rent a portion of its unused spectrum to the NIO for revenue such that the NIO can obtain access to the spectrum to serve its customers. This proposed framework achieves green communications through both resource sharing and energy saving. Our paper aims to analyze the interplay between TSO and NIO, and create a win–win situation to provide sufficient incentives for them to cooperate on this green communications. A multistage Stackelberg game is formulated, where TSO and NIO sequentially determine the total bandwidth supply for sharing, the infrastructure leasing price, the amount of infrastructure to lease, the spectrum leasing price, and the amount of spectrum to lease to maximize their utilities. The best strategies that will be taken by the TSO and NIO under various deployment scenarios are analyzed. Evaluation results show that the proposed green spectrum and infrastructure leasing framework is a promising scheme under which both TSO and NIO can benefit, and their utilities can be maximized in terms of user data throughput and revenue/payment, which provides sufficient incentives for them to cooperate. Autors: Xiaoshuang Xing;Biao Chen;Hang Liu;Xiuzhen Cheng;Wei Zhou;Dechang Chen; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6511 - 6522 Publisher: IEEE
» Games on Large Networks: Information and Complexity
 Abstract:In this work, we study Static and Dynamic Games on Large Networks of interacting agents, assuming that the players have some statistical description of the interaction graph, as well as some local information. Inspired by Statistical Physics, we consider statistical ensembles of games and define a Probabilistic Approximate equilibrium notion for such ensembles. A Necessary Information Complexity notion is introduced to quantify the minimum amount of information needed for the existence of a Probabilistic Approximate equilibrium. We then focus on some special classes of games for which it is possible to derive upper and/or lower bounds for the complexity. At first, static and dynamic games on random graphs are studied and their complexity is determined as a function of the graph connectivity. In the low complexity case, we compute Probabilistic Approximate equilibrium strategies. We then consider static games on lattices and derive upper and lower bounds for the complexity, using contraction mapping ideas. A LQ game on a large ring is also studied numerically. Using a reduction technique, approximate equilibrium strategies are computed and it turns out that the complexity is relatively low. Autors: Ioannis Kordonis;George P. Papavassilopoulos; Appeared in: IEEE Transactions on Automatic Control Publication date: Jul 2017, volume: 62, issue:7, pages: 3178 - 3192 Publisher: IEEE
» Gamesman Problems [Gamesman Problems]
 Abstract: Autors: Athanasios Kakarountas; Appeared in: IEEE Potentials Publication date: Jul 2017, volume: 36, issue:4, pages: 48 - 48 Publisher: IEEE
» Gamesman Soutions [Gamesman Solutions]
 Abstract: Autors: Athanasios Kakarountas; Appeared in: IEEE Potentials Publication date: Jul 2017, volume: 36, issue:4, pages: 6 - 6 Publisher: IEEE
» GaN Nanowire n-MOSFET With 5 nm Channel Length for Applications in Digital Electronics
 Abstract:We study the performance of GaN nanowire n-MOSFETs (GaN-NW-nFETs) with a channel length, Lg = 5 nm based on fully ballistic quantum transport simulations. Our simulation results show high I and excellent on-off characteristics with Q /SS -decade/-mV calculated for I nA/ and V V. These results represent: 1) ~ 15% higher than Si-NW-nFET and 2) ~ 17% better Q than Si-NW-nFET, all with Lg = 5 nm, thus suggesting the GaN n-channel, an intriguing option for application in logic at sub-10-nm channel length. The superior performance of the GaN channel compared with Si and other semiconductors at this scaled dimension can be attributed to its relatively higher effective mass of electron and lower permittivity. Autors: Nadim Chowdhury;Giuseppe Iannaccone;Gianluca Fiori;Dimitri A. Antoniadis;Tomás Palacios; Appeared in: IEEE Electron Device Letters Publication date: Jul 2017, volume: 38, issue:7, pages: 859 - 862 Publisher: IEEE
» Gas Bubble Effects and Elimination in Ultrasonic Measurement of Particle Concentrations in Solid–Liquid Mixing Processes
 Abstract:In this paper, the online measurement of particle concentrations in suspensions containing gas bubbles is studied using the ultrasonic spectra and the synergy interval partial least squares regression (Si-PLS) model in the solid-liquid mixing processes. At first, a comparison is made among the ultrasonic signals obtained from suspensions and pure water with and without gas bubbles and the gas bubble effects of high agitation speeds on ultrasonic measurement are evaluated. A moving average and standard deviation method is developed to deal with the real-time ultrasonic signals, aiming to decrease the fluctuations and noises of signals and improve the stability of signals. Then, based on the optimal spectral subintervals selected with the Si-PLS model, the prediction model for the particle concentrations is built, which considers the gas bubble effects as an interferent. The optimal model, of which the root-mean-square error of the prediction subset is 0.38 wt%, is successfully applied to measure the concentration of TiO2 suspensions in the range of 0-15.79 wt% when the agitation speed is less than 1200 r/min. The online measurement results suggest that the proposed method has the potential to be a useful tool for eliminating gas bubble effects and measuring particle concentrations in the solid-liquid mixing processes. Autors: Xiaobin Zhan;Yili Yang;Jian Liang;Tielin Shi;Xiwen Li; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Jul 2017, volume: 66, issue:7, pages: 1711 - 1718 Publisher: IEEE
» Gaussian Mixture Based Probabilistic Load Flow For LV-Network Planning
 Abstract:Due the many uncertainties present in the evolution of loads and distributed generation, the use of probabilistic load flow in low voltage (LV) networks is essential for the evaluation of the robustness of these networks from a planning perspective. The main challenge with the assessment of LV-networks is the sheer number of networks which need to be analyzed. Moreover, most loads in the LV-network have a volatile nature and are hard to approximate using conventional probability distributions. This can be overcome by the use of a Gaussian mixture distribution in load modeling. Taking advantage of its radial nature and high R/X ratios, the LV-network can be analyzed more efficiently from a computation viewpoint. By the application of simplifications defined in this paper, the backward–forward load flow can be solved analytically. This allows for the direct computation of the load flow equations with a Gaussian mixture distribution as load. When using this new approach, the required calculation time for small networks can be decreased to 3% of the time it takes to generate a similar accuracy with a Monte Carlo approach. The practical application of this load flow calculation method is illustrated with a case study on PV penetration. Autors: Michiel Nijhuis;Madeleine Gibescu;Sjef Cobben; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 2878 - 2886 Publisher: IEEE
» General Framework for Network Throughput Maximization in Sink-Based Energy Harvesting Wireless Sensor Networks
 Abstract:Due to the advancement in energy harvesting wireless sensor networks (EH-WSNs), the data collection from one-hop stationary sensor nodes using a path-constrained mobile sink has become one of the challenging issues. Toward the throughput improvement, we propose a general framework for network throughput maximization (NTM) problem by optimizing practically feasible parameters. For each proposed scenario, a mixed integer linear programming (MILP) optimization model is introduced for the problem formulation. Due to the NP-Hardness of the MILP models, we design two efficient algorithms namely as ODSAA and ODAA for two practically implementable scenarios. Having a preknowledge about the deployed location of nodes, the proposed algorithms run centrally by sink and find the sub-optimal solutions within a reasonable computation time. Furthermore, under the uniform distribution of energy harvesting, we find out two threshold points on, respectively, energy harvesting mean and battery capacity of nodes after which the network throughput reaches a stable point. Finally, simulations are conducted on a different set of node deployments, which the results confirm that the proposed algorithms significantly improve the data throughput collected by sink and also the theoretical thresholds provide a confidence interval of 90 percent. Autors: Abbas Mehrabi;Kiseon Kim; Appeared in: IEEE Transactions on Mobile Computing Publication date: Jul 2017, volume: 16, issue:7, pages: 1881 - 1896 Publisher: IEEE
» Generalized Δ-Circuit Concept for Integration of Distributed Generators in Online Short-Circuit Calculations
 Abstract:In this paper, a novel concept of Generalized Δ-circuit is proposed, that enables integration of distributed generators (DGs) based on contemporary technologies into the short-circuit calculations of large-scale distribution systems. Modern DG models, such as doubly fed induction generators (DFIGs) and three-phase inverter based DGs (IBDGs) differ from the classical synchronous and induction generator models. It is shown that their models cannot be integrated in traditional short-circuit calculation procedures because they include a large number of possible fault current control strategies. Therefore, the concept of Generalized Δ-circuit is proposed and allows for any control strategy implemented in modern DGs to be integrated in the short-circuit calculation procedure. An improved backward/forward sweep procedure is developed for calculation of the Generalized Δ-circuit state. The faulted system state is calculated by the superposition of the known prefault state and calculated Generalized Δ-circuit state. Results show that unlike previously developed online short-circuit calculations, the proposed method can handle DFIGs and IBDGs with arbitrary selected fault current control strategies. Autors: Luka Strezoski;Marija Prica;Kenneth A. Loparo; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3237 - 3245 Publisher: IEEE
» Generalized Derivatives for Hybrid Systems
 Abstract:Established sensitivity results for hybrid discrete/continuous dynamic systems are generalized by relaxing smoothness assumptions on the functions governing the systems' continuous evolution and discrete event handling. The new results only require L-smoothness of these functions in the sense of Nesterov, instead of continuous differentiability. Parametric lexicographic derivatives for such a hybrid system provide useful local first-order sensitivity information, and are described as the unique solutions of auxiliary hybrid systems. This sensitivity analysis framework permits generalized derivative evaluation even for certain hybrid systems in which small changes in parameters can change the sequence of discrete modes visited. To handle parametric sensitivities of event times that are not known explicitly, conditions are provided under which a local inverse function or implicit function is L-smooth, with lexicographic derivatives that are described as the unique solutions of certain equation systems. These equation systems are readily solved when the functions involved are piecewise differentiable. Autors: Kamil A. Khan;Paul I. Barton; Appeared in: IEEE Transactions on Automatic Control Publication date: Jul 2017, volume: 62, issue:7, pages: 3193 - 3208 Publisher: IEEE
» Generalized RF Time-Domain Imaging Technique for Moving Objects on Conveyor Belts in Real Time
 Abstract:In this paper, an attractive time-domain RF imaging technique is proposed for online monitoring of moving objects over conveyor belts. The proposed technique combines the strength of the time-domain approach and the Riccati equation-based ultrawideband reconstruction method in order to image the stratified lossy dielectric medium. The applicability of the proposed method is first tested under stationary condition by reconstructing the permittivity and conductivity image of the target area comprising of various standard samples placed in free space. For moving objects under real-world scenario, two antenna arrays comprised of ultra-wideband Vivaldi elements are designed and tested. These arrays are then employed to produce the 2-D microwave image of various wooden-based samples and human mannequins carrying metal object concealed behind the cloth. The obtained real-time microwave image of the test medium shows that the proposed RF imaging technique is best suited for online monitoring of stationary as well as moving targets, where the structural as well as the electrical properties of the test medium can be obtained through a nondestructive process without using any iterative scheme. Autors: Zubair Akhter;Abhishek Kumar Jha;Mohammad Jaleel Akhtar; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Jul 2017, volume: 65, issue:7, pages: 2536 - 2546 Publisher: IEEE
» Generating Vectored Thrust With the Rotational Paddling Gait of an ePaddle-EGM Mechanism: Modeling and Experimental Verifications
 Abstract:An eccentric paddle mechanism based on the epicyclic gear mechanism (ePaddle-EGM), proposed to enhance the mobility of amphibious robots for multiterrains tasks, can execute several terrestrial and aquatic gaits. In this paper, we rectify the experimental setup as well as the thrust modeling to do further research on rotational paddling gait. The effects of the rotational period and the location of paddle shaft to the thrust are analyzed. Besides the amplitude features, experimental results also illustrate the vector character of thrust generated by the rotational paddling gait. Autors: Yayi Shen;Huayan Pu;Yi Sun;Shugen Ma;Shaorong Xie;Jun Luo;Wenchuan Jia; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Jul 2017, volume: 42, issue:3, pages: 522 - 531 Publisher: IEEE
» Generation Expansion Planning With Large Amounts of Wind Power via Decision-Dependent Stochastic Programming
 Abstract:Power generation expansion planning needs to deal with future uncertainties carefully, given that the invested generation assets will be in operation for a long time. Many stochastic programming models have been proposed to tackle this challenge. However, most previous works assume predetermined future uncertainties (i.e., fixed random outcomes with given probabilities). In several recent studies of generation assets’ planning (e.g., thermal versus renewable), new findings show that the investment decisions could affect the future uncertainties as well. To this end, this paper proposes a multistage decision-dependent stochastic optimization model for long-term large-scale generation expansion planning, where large amounts of wind power are involved. In the decision-dependent model, the future uncertainties are not only affecting but also affected by the current decisions. In particular, the probability distribution function is determined by not only input parameters but also decision variables. To deal with the nonlinear constraints in our model, a quasi-exact solution approach is then introduced to reformulate the multistage stochastic investment model to a mixed-integer linear programming model. The wind penetration, investment decisions, and the optimality of the decision-dependent model are evaluated in a series of multistage case studies. The results show that the proposed decision-dependent model provides effective optimization solutions for long-term generation expansion planning. Autors: Yiduo Zhan;Qipeng P. Zheng;Jianhui Wang;Pierre Pinson; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3015 - 3026 Publisher: IEEE
» Geoacoustic Inversion of Airgun Data Under Influence of Internal Waves
 Abstract:In this paper, broadband airgun data from the 1995 Shallow Water Acoustics in Random Media (SWARM'95) experiment are analyzed to study the influence of internal waves on sound propagation and modal behavior, and the subsequent effects on geoacoustic inversion. Modal behavior and fluctuation due to sound intensity focusing and defocusing, when the leading front of internal waves is parallel to and approaches or passes through the acoustic propagation track, are presented. A modal filtering technique, the time-warping transform, is applied to the airgun data to resolve dispersed modes. The extracted modes are used to estimate seabed model parameters by geoacoustic inversion. Two scenarios, defocusing and focusing periods containing 14 events, are selected for study. Seven data sets for each type (defocusing or focusing) are analyzed to extract dispersion curves and carry out geoacoustic inversion. The inversion results for each type of the events are similar with a small standard deviation from the mean. However, the mean values and standard deviations for the defocusing and focusing types are quite different. The impacts of internal waves on inversion results are presented and discussed. Autors: Hefeng Dong;Mohsen Badiey;N. Ross Chapman; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Jul 2017, volume: 42, issue:3, pages: 632 - 638 Publisher: IEEE
» Geometric Deep Learning: Going beyond Euclidean data
 Abstract:Many scientific fields study data with an underlying structure that is non-Euclidean. Some examples include social networks in computational social sciences, sensor networks in communications, functional networks in brain imaging, regulatory networks in genetics, and meshed surfaces in computer graphics. In many applications, such geometric data are large and complex (in the case of social networks, on the scale of billions) and are natural targets for machine-learning techniques. In particular, we would like to use deep neural networks, which have recently proven to be powerful tools for a broad range of problems from computer vision, natural-language processing, and audio analysis. However, these tools have been most successful on data with an underlying Euclidean or grid-like structure and in cases where the invariances of these structures are built into networks used to model them. Autors: Michael M. Bronstein;Joan Bruna;Yann LeCun;Arthur Szlam;Pierre Vandergheynst; Appeared in: IEEE Signal Processing Magazine Publication date: Jul 2017, volume: 34, issue:4, pages: 18 - 42 Publisher: IEEE
» Getting a Leg Up
 Abstract:From the time that he was a child, Brian Jones dreamed of becoming a jet pilot and an astronaut. Jones grew up in a family of servicemen, with both his father and grandfather spending time in the U.S. Navy. The pull of the U.S. Naval Academy and the potential for adventure and exploration led Jones to enter the academy in Annapolis, Maryland, to study aerospace engineering following his graduation from high school. His childhood dreams were clearly in sight. Autors: Craig Causer; Appeared in: IEEE Potentials Publication date: Jul 2017, volume: 36, issue:4, pages: 39 - 43 Publisher: IEEE
» GPU-Based Fast Decoupled Power Flow With Preconditioned Iterative Solver and Inexact Newton Method
 Abstract:Power flow is the most fundamental computation in power system analysis. Traditionally, the linear solution in power flow is solved by a direct method like LU decomposition on a CPU platform. However, the serial nature of the LU-based direct method is the main obstacle for parallelization and scalability. In contrast, iterative solvers, as alternatives to direct solvers, are generally more scalable with better parallelism. This study presents a fast decouple power flow (FDPF) algorithm with a graphic processing unit (GPU)-based preconditioned conjugate gradient iterative solver. In addition, the Inexact Newton method is integrated to further improve the GPU-based parallel computing performance for solving FDPF. The results show that the GPU-based FDPF maintains the same precision and convergence as the original CPU-based FDPF, while providing considerable performance improvement for several large-scale systems. The proposed GPU-based FDPF with the Inexact Newton method gives a speedup of 2.86 times for a system with over 10 000 buses if compared with traditional FDPF, both implemented based on MATLAB. This demonstrates the promising potential of the proposed FDPF computation using a preconditioned iterative solver under GPU architecture. Autors: Xue Li;Fangxing Li;Haoyu Yuan;Hantao Cui;Qinran Hu; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 2695 - 2703 Publisher: IEEE
» GPU-Based Parallel Implementation of Fisher Detector for Infrasonic Spectrum Sensing Systems
 Abstract:Fisher statistics-based signal detection is a widely-used powerful multi-sensor infrasound spectrum sensing method. However, this method requires the repeated computation of test statistics for each element of a grid of slowness vectors, which imposes a high computational complexity and leads directly to a raised processing time. Since conventional systems often have very stringent speed requirements for real-time surveillance applications, this disadvantage leads a limited application of Fisher detectors (FDs) for several infrasonic sensing purposes. In this paper, we propose a strategy for implementation of FD with reduced time-consumption. This strategy is based on the fact that the detection process for slowness-grid elements can be performed in a parallel manner using powerful graphics processing units, in contrast with conventional FDs. The results of simulations show that our strategy promises very significant time-savings compared with conventional FDs, which enables it as a good candidate for real-time applications. Autors: Hamed Sadeghi;Mojtaba Shahrab; Appeared in: IEEE Sensors Journal Publication date: Jul 2017, volume: 17, issue:14, pages: 4570 - 4582 Publisher: IEEE
» Graph Guessing Games and Non-Shannon Information Inequalities
 Abstract:Guessing games for directed graphs were introduced by Riis for studying multiple unicast network coding problems. In a guessing game, the players toss generalised dice and can see some of the other outcomes depending on the structure of an underlying digraph. They later guess simultaneously the outcome of their own die. Their objective is to find a strategy, which maximizes the probability that they all guess correctly. The performance of the optimal strategy for a graph is measured by the guessing number of the digraph. Christofides and Markström studied guessing numbers of undirected graphs and defined a strategy which they conjectured to be optimal. One of the main results of this paper is a disproof of this conjecture. The main tool so far for computing guessing numbers of graphs is information theoretic inequalities. The other main result of this paper is that Shannon’s information inequalities, which work particularly well for a wide range of graph classes, are not sufficient for computing the guessing number. Finally, we pose a few more interesting questions some of which we can answer and some which we leave as open problems. Autors: Rahil Baber;Demetres Christofides;Anh N. Dang;Emil R. Vaughan;Søren Riis; Appeared in: IEEE Transactions on Information Theory Publication date: Jul 2017, volume: 63, issue:7, pages: 4257 - 4267 Publisher: IEEE
» Green Networking in Cellular HetNets: A Unified Radio Resource Management Framework With Base Station ON/OFF Switching
 Abstract:In this paper, the problem of energy efficiency in cellular heterogeneous networks (HetNets) is investigated using radio resource and power management combined with the base station (BS) ON/OFF switching. The objective is to minimize the total power consumption of the network while satisfying the quality of service requirements of each connected user. We consider the case of coexisting macrocell BS, small cell BSs, and private femtocell access points (FAPs). Three different network scenarios are investigated, depending on the status of the FAPs, i.e., HetNets without FAPs, HetNets with closed FAPs, and HetNets with semiclosed FAPs. A unified framework is proposed to simultaneously allocate spectrum resources to users in an energy efficient manner and switch OFF redundant small cell BSs. The high complexity dual decomposition technique is employed to achieve optimal solutions for the problem. A low complexity iterative algorithm is also proposed and its performances are compared to those of the optimal technique. The particularly interesting case of semiclosed FAPs, in which the FAPs accept to serve external users, achieves the highest energy efficiency due to increased degrees of freedom. In this paper, a cooperation scheme between FAPs and mobile operator is also investigated. The incentives for FAPs, e.g., renewable energy sharing and roaming prices, enabling cooperation are discussed to be considered as a useful guideline for interoperator agreements. Autors: Hakim Ghazzai;Muhammad Junaid Farooq;Ahmad Alsharoa;Elias Yaacoub;Abdullah Kadri;Mohamed-Slim Alouini; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5879 - 5893 Publisher: IEEE
» Grid Structural Characteristics as Validation Criteria for Synthetic Networks
 Abstract:This paper presents a methodology and set of validation criteria for the systematic creation of synthetic power system test cases. The synthesized grids do not correspond to any real grid and are, thus, free from confidentiality requirements. The cases are built to match statistical characteristics found in actual power grids. First, substations are geographically placed on a selected territory, synthesized from public information about the underlying population and generation plants. A clustering technique is employed, which ensures the synthetic substations meet realistic proportions of load and generation, among other constraints. Next, a network of transmission lines is added. This paper describes several structural statistics to be used in characterizing real power system networks, including connectivity, Delaunay triangulation overlap, dc power flow analysis, and line intersection rate. The paper presents a methodology to generate synthetic line topologies with realistic parameters that satisfy these criteria. Then, the test cases can be augmented with additional complexities to build large, realistic cases. The methodology is illustrated in building a 2000 bus public test case that meets the criteria specified. Autors: Adam B. Birchfield;Ti Xu;Kathleen M. Gegner;Komal S. Shetye;Thomas J. Overbye; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3258 - 3265 Publisher: IEEE
» Griddle: Video Gaming for Power System Education
 Abstract:The motivation and training of a proficient and diverse pool of power engineers, system operators, and policymakers is an important challenge for the electric industry. Power system experts are increasingly in demand globally to facilitate transitions to more environmentally friendly energy systems. More generally, citizens with a basic understanding of load balancing and renewable energy sources are more effective partners in increasingly complex power economies and political decisions. To address the need for an accessible general introduction to power systems, we are developing Griddle, an educational video game that introduces secondary school students to the basics of power system design, scheduling, and operation. We describe the design of Griddle's gameplay and underlying simulation, improvements made in response to user feedback, alignment with emerging teaching standards, and a high school classroom evaluation (n = 178) of Griddle's significant transformative impact, with the goal of validating the game-based learning approach and sharing “lessons learned” with designers of related tools. We find that Griddle is effective at engaging students and presents evidence that it helps students integrate key concepts, and we identify areas where further development and study are needed. Autors: Michael A. Cohen;Greg O. Niemeyer;Duncan S. Callaway; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3069 - 3077 Publisher: IEEE
» Guest Editorial Special Section on Design, Modeling, and Control of Hybrid and Multi-source Vehicles
 Abstract: Autors: Loïc Boulon;Claudio Rossi;Anna Stefanopoulou;Rochdi Trigui; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5518 - 5519 Publisher: IEEE
» Hardware-In-the-Loop Simulation of Traction Power Supply for Power Flows Analysis of Multitrain Subway Lines
 Abstract:Multitrain systems are difficult to study due to the size of the system and its specificities. To tackle these difficulties, this paper develops a reduced-scale power Hardware-In-the-Loop (HIL) simulation dedicated to subway line emulations. Energetic macroscopic representation (EMR) is used to organize the HIL simulation. A first mono-train HIL simulation is developed and validated by experimental results. The HIL simulation is then extended to a two-train study to analyze the different power flows between subsystems. Autors: Clément Mayet;Philippe Delarue;Alain Bouscayrol;Eric Chattot; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5564 - 5571 Publisher: IEEE
» Harnessing Bursty Interference in Multicarrier Systems With Output Feedback
 Abstract:We study parallel two-user interference channels when the interference is bursty and feedback is available from the respective receivers. Presence of interference in each subcarrier is modeled as a memoryless Bernoulli random state. The states across subcarriers are drawn from an arbitrary joint distribution with the same marginal probability for each subcarrier and instantiated independent and identically distributed (i.i.d.) over time. For the linear deterministic setup with symmetric interference in each subcarrier, we give a complete characterization of the capacity region. For the analogous setup with Gaussian noise, we give outer bounds and a tight generalized degrees of freedom characterization. We propose a novel helping mechanism, which enables subcarriers in very strong interference regime to help in recovering interfered signals for subcarriers in strong and weak interference regimes. Depending on the interference and burstiness regime, the inner bounds either employ the proposed helping mechanism to code across subcarriers or treat the subcarriers separately. The outer bounds demonstrate a connection to a subset entropy inequality by Madiman and Tetali. Autors: Shaunak Mishra;I-Hsiang Wang;Suhas N. Diggavi; Appeared in: IEEE Transactions on Information Theory Publication date: Jul 2017, volume: 63, issue:7, pages: 4430 - 4452 Publisher: IEEE
» Harsanyi Power Solutions in Coalitional Control Systems
 Abstract:In coalitional control the connections among the different parts of a control network evolve dynamically to achieve a trade-off between communication burden and control performance, and the coalition choices are made by selecting the network topology with minimal payoff. This work analyzes how Harsanyi power solutions for games in coalitional control schemes, which generalize the Shapley value in this context, can be used to quantify the value of the communication links under different control topologies. To this end, a game among these links is considered, and the payoff that each link receives is determined by the Harsanyi power solutions, which take into account the communication costs and the predicted infinite-horizon costs for these topologies. The concept of link power measure as a centrality index to configure the communication costs is also introduced. As a result, a more computationally efficient design method with respect to previous works has been proposed. Autors: Francisco Javier Muros;Encarnación Algaba;José María Maestre;Eduardo F. Camacho; Appeared in: IEEE Transactions on Automatic Control Publication date: Jul 2017, volume: 62, issue:7, pages: 3369 - 3381 Publisher: IEEE
» Head Dependence of Pump-Storage-Unit Model Applied to Generation Scheduling
 Abstract:This paper presents a head-dependent model for pump storage units (PSUs) in a power system for short-term generation scheduling over one week. A hydraulic system with upper and lower reservoirs, each having their own in and out river flows, is considered. Hydraulic conditions, as well as head effects, are explicitly modeled for both generation and pumping modes of the PSUs. The problem is solved by the branch-and-cut method to obtain a near-optimal solution. Test results of an hourly generation schedule, including comparisons of pump efficiencies, hydraulic conditions, and operating costs of the PSUs for a real power system, are presented. Autors: Cheng-Hung Chen;Nanming Chen;Peter B. Luh; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 2869 - 2877 Publisher: IEEE
» Heartbeat Signal Detection From Analysis of Airflow in Rat Airway Under Different Depths of Anaesthesia Conditions
 Abstract:We inserted a tubular flow sensor incorporating micro-electro-mechanical systems technologies directly into the rat airway and analyzed the airflow waveforms obtained under different depths of anaesthesia conditions by using discrete Fourier transformation (DFT) to evaluate the heartbeat frequency. The electrocardiogram (ECG) signal was used as the reference heartbeat frequency. The calibration curve of the flow sensor used to measure the oscillating airflow in the rat airway was determined on the basis of King’s law. The airflow waveform at the rat airway caused by only the heartbeat was measured by applying deep anaesthesia; the waveform frequency coincided with the simultaneously measured ECG signal frequency. DFT analysis of the airflow signals measured under deep and shallow anaesthesia conditions verified the fundamental heartbeat frequency values. The airflow components related to heartbeat motion were successfully extracted by using the heartbeat frequency spectrum. The respiration and heartbeat signals were thus successfully detected. Autors: Hidetaka Kawaoka;Takayuki Yamada;Miyoko Matsushima;Tsutomu Kawabe;Yoshihiro Hasegawa;Mitsuhiro Shikida; Appeared in: IEEE Sensors Journal Publication date: Jul 2017, volume: 17, issue:14, pages: 4369 - 4377 Publisher: IEEE
» HELOS: Heterogeneous Load Scheduling for Electric Vehicle-Integrated Microgrids
 Abstract:With increasing concerns about worldwide environmental conditions and rapid development of renewable energy technologies, microgrids have been regarded as a promising solution to reduce the burden of infrastructure-based power systems. However, due to the intrinsically intermittent features of existing renewable energy, along with random residential behavior patterns, unpredictable plugged-in or unplugged actions of electric vehicles (EVs) and the time-varying price of electricity, it is challenging for microgrid operators to efficiently perform load scheduling and energy management. In this paper, we propose an online algorithm to conduct cost-aware scheduling of EV loads and energy supplies for microgrids. We formulate this problem into a stochastic optimization problem with the objective of minimizing the time-average cost of a microgrid, including the purchase cost of electricity from the main grid, the cost of charging and discharging batteries, renewable harvesting costs, and life-cycle greenhouse-gas emission costs. To solve this problem, the key idea is to exploit the dynamics of the price of electricity to conduct battery charging and discharging operations, renewable energy harvesting, and schedule EV loads properly. Our method is based on the Lyapunov optimization technique, which has low computational complexity and only requires limited prediction of price information. The theoretical analysis of our algorithm confirms that the proposed strategy can achieve optimality with explicit bound. By conducting extensive real-data driven simulations, we demonstrate that our proposed algorithm can achieve much lower cost and be more eco-friendly than other alternative solutions. Autors: Gaoxiang Li;Di Wu;Jiefeng Hu;Yong Li;M. Shamim Hossain;Ahmed Ghoneim; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5785 - 5796 Publisher: IEEE
» HEp-2 Specimen Image Segmentation and Classification Using Very Deep Fully Convolutional Network
 Abstract:Reliable identification of Human Epithelial-2 (HEp-2) cell patterns can facilitate the diagnosis of systemic autoimmune diseases. However, traditional approach requires experienced experts to manually recognize the cell patterns, which suffers from the inter-observer variability. In this paper, an automatic pattern recognition system using fully convolutional network (FCN) was proposed to simultaneously address the segmentation and classification problem of HEp-2 specimen images. The proposed system transforms the residual network (ResNet) to fully convolutional ResNet (FCRN) enabling the network to perform semantic segmentation task. A sand-clock shape residual module is proposed to effectively and economically improve the performance of FCRN. The publicly available I3A-2014 data set was used to train the FCRN model to classify HEp-2 specimen images into seven catalogs: homogeneous, speckled, nucleolar, centromere, golgi, nuclear membrane, and mitotic spindle. The proposed system achieves a mean class accuracy of 94.94% for leave-one-out tests, which outperforms the winner of ICPR 2014, i.e., 89.93%. At the same time, our model also achieves a segmentation accuracy of 89.03%, which is 19.05% higher than that of the benchmark approach, i.e., 69.98%. Autors: Yuexiang Li;Linlin Shen;Shiqi Yu; Appeared in: IEEE Transactions on Medical Imaging Publication date: Jul 2017, volume: 36, issue:7, pages: 1561 - 1572 Publisher: IEEE
» Hierarchical Guidance Filtering-Based Ensemble Classification for Hyperspectral Images
 Abstract:Joint spectral and spatial information should be fully exploited in order to achieve accurate classification results for hyperspectral images. In this paper, we propose an ensemble framework, which combines spectral and spatial information in different scales. The motivation of the proposed method derives from the basic idea: by integrating many individual learners, ensemble learning can achieve better generalization ability than a single learner. In the proposed work, the individual learners are obtained by joint spectral-spatial features generated from different scales. Specially, we develop two techniques to construct the ensemble model, namely, hierarchical guidance filtering (HGF) and matrix of spectral angle distance (mSAD). HGF and mSAD are combined via a weighted ensemble strategy. HGF is a hierarchical edge-preserving filtering operation, which could produce diverse sample sets. Meanwhile, in each hierarchy, a different spatial contextual information is extracted. With the increase of hierarchy, the pixels spectra tend smooth, while the spatial features are enhanced. Based on the outputs of HGF, a series of classifiers can be obtained. Subsequently, we define a low-rank matrix, mSAD, to measure the diversity among training samples in each hierarchy. Finally, an ensemble strategy is proposed using the obtained individual classifiers and mSAD. We term the proposed method as HiFi-We. Experiments are conducted on two popular data sets, Indian Pines and Pavia University, as well as a challenging hyperspectral data set used in 2014 Data Fusion Contest (GRSS_DFC_2014). An effectiveness analysis about the ensemble strategy is also displayed. Autors: Bin Pan;Zhenwei Shi;Xia Xu; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Jul 2017, volume: 55, issue:7, pages: 4177 - 4189 Publisher: IEEE
» High Aspect Ratio Silicon Structures Produced via Metal-Assisted Chemical Etching and Assembly Technology for Cantilever Fabrication
 Abstract:This paper presents a metal-assisted chemical etching (MACE) method for high aspect silicon structures. Ultrahigh aspect trenches and pillars of 400 and 80, respectively, have been achieved using MACE. A survey of the MACE method investigated the etching time, pattern sizes, and concentration of etching solution. In addition, a comparison of the etching methods related to the etching depth, surface roughness, and aspect ratio structure, etc., between the deep reactive ion etching and MACE methods has been reported. A simple method for cantilever fabrication has been proposed and demonstrated. Cantilever-based pillars fabricated by MACE were successfully produced via an assembly technology. The pillars were assembled onto a glass substrate and fixed with a conductive glue. The fabricated cantilever showed a resonance frequency of 235 kHz and a quality factor of 800. Autors: Nguyen Van Toan;Masaya Toda;Takahito Ono; Appeared in: IEEE Transactions on Nanotechnology Publication date: Jul 2017, volume: 16, issue:4, pages: 567 - 573 Publisher: IEEE
» High Breakdown Voltage (−201) $\beta$ -Ga2O3 Schottky Rectifiers
 Abstract:-Ga2O3 Schottky barrier diodes were fabricated in a vertical geometry structure consisting of Ni/Au rectifying contacts without edge termination on Si-doped epitaxial layers (, cm on Sn-doped bulk Ga2O3 substrates with full-area Ti/Au back Ohmic contacts. The reverse breakdown voltage, , was a function of rectifying contact area, ranging from 1600 V at cm2 (20- diameter) to ~250 V at cm (0.53-mm diameter). The current density near breakdown was not strongly dependent on contact circumference but did scale with contact area, indicating that the bulk current contribution was dominant. The lowest ON-state resistance, , was 1.6 cm2 for the largest diode and 25 cm2 for the 1600-V rectifier, leading to a Baliga figure-of-merit ( for the latter of approximately 102.4 MWcm. The ON-OFF ratio was measured at a forward voltage of 1.3 V and ranged from to for reverse biases from −5 to −40 V and showed only a small dependence on temperature in the range from 25 °C to 100 °C. Autors: Jiancheng Yang;Shihyun Ahn;F. Ren;S. J. Pearton;Soohwan Jang;A. Kuramata; Appeared in: IEEE Electron Device Letters Publication date: Jul 2017, volume: 38, issue:7, pages: 906 - 909 Publisher: IEEE

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