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

» A Robust Translational Motion Compensation Method for ISAR Imaging Based on Keystone Transform and Fractional Fourier Transform Under Low SNR Environment
 Abstract:In this work, a parametric-based approach is proposed to perform joint range alignment and phase adjustment based on the intention of fully exploiting the energy of all the scatterers in the moving target and the two-dimensional coherent accumulation gain of both range and azimuth compressions. To that end, first, translational motion is modeled as a polynomial signal, and inspired by the fact that all the scatterers in the moving target experience the same translational range history, the phase difference operation and keystone transform (KT) are utilized to transform the energy of all the scatterers into one range cell. Second, by the virtue of the fractional Fourier transform (FrFT), the energy of all the scatterers is coherently accumulated into a peak point, and from which the polynomial coefficients can be obtained accurately. With the estimated polynomial coefficients, the dechirp operation and KT are applied jointly to compensate range misalignment and phase error. The analysis of the proposed method shows that it is of low computational complexity due to avoiding multidimensional search and improves the output SNR providing satisfactory low SNR performance. The experimental results are provided to demonstrate the performance of the proposed method compared with the state-of-the-art algorithms. Autors: Dong Li;Muyang Zhan;Hongqing Liu;Yong Liao;Guisheng Liao; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2140 - 2156 Publisher: IEEE
» A Seaglider-Integrated Digital Monitor for Bioacoustic Sensing
 Abstract:An acoustic Digital MONitor (DMON) has been integrated into a Seaglider autonomous underwater vehicle to serve as a general-use tool for passive acoustic sensing of marine mammal vocalizations. The system is being developed as a complement to conventional ship-based cetacean survey methods. The acoustic system includes three omnidirectional hydrophones, one located on centerline of the aft payload hatch and one on each wingtip. An onboard real-time detector has been implemented to record an audio sample if ambient noise has risen above a user-prescribed signal-to-noise ratio (SNR) threshold level. The data size and the number of detections are available in semi-real time, and the acoustic data are retrieved upon recovery of the instrument. Because the DMON system interfaces with the Seaglider firmware, the glider pilot has the capability to modify several operational parameters governing the collection of acoustic data while the glider is deployed to tailor the data recording to the desired mission objectives. This implementation is referred to as the Seaglider Customizable Sampling Configuration (SCSC) DMON and has recorded a wide variety of cetacean vocal activity offshore the Hawaiian Islands. Autors: Lora J. Van Uffelen;Ethan H Roth;Bruce M. Howe;Erin M. Oleson;Yvonne Barkley; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Oct 2017, volume: 42, issue:4, pages: 800 - 807 Publisher: IEEE
» A Self-Adaptive Capacitive Compensation Technique for Body Channel Communication
 Abstract:In wireless body area network, capacitive-coupling body channel communication (CC-BCC) has the potential to attain better energy efficiency over conventional wireless communication schemes. The CC-BCC scheme utilizes the human body as the forward signal transmission medium, reducing the path loss in wireless body-centric communications. However, the backward path is formed by the coupling capacitance between the ground electrodes (GEs) of transmitter (Tx) and receiver (Rx), which increases the path loss and results in a body posture dependent backward impedance. Conventional methods use a fixed inductor to resonate with the backward capacitor to compensate the path loss, while it's not effective in compensating the variable backward impedance induced by the body movements. In this paper, we propose a self-adaptive capacitive compensation (SACC) technique to address such a problem. A backward distance detector is introduced to estimate the distance between two GEs of Tx and Rx, and a backward capacitance model is built to calculate the backward capacitance. The calculated backward capacitance at varying body posture is compensated by a digitally controlled tunable inductor (DCTI). The proposed SACC technique is validated by a prototype CC-BCC system, and measurements are taken on human subjects. The measurement results show that 9dB–16 dB channel enhancement can be achieved at a backward path distance of 1 cm-10 cm. Autors: Jingna Mao;Huazhong Yang;Yong Lian;Bo Zhao; Appeared in: IEEE Transactions on Biomedical Circuits and Systems Publication date: Oct 2017, volume: 11, issue:5, pages: 1001 - 1012 Publisher: IEEE
» A Self-Calibrated Cryogenic Current Cell for 4.2 K Current Steering D/A Converters
 Abstract:This brief presents a cryogenic CMOS unit current cell operating from room temperature down to 4.2 K, and it is primarily designed for low temperature current steering (CS) D/A converters (DACs). A novel structure along with an analog calibration technique is proposed in designing the cell that helps it to overcome low temperature induced nonlinear and mismatch effects. Due to the flexible configuration of the cell architecture, it can be used in both LSB and MSB parts of a partially-segmented CS DAC. The current cell retains its 4-bit precision level from 300 K down to 4.2 K, and drives a load to 6.8 mV in 600 ps rise time. A 6-bit converter utilizing the cell achieves differential and integral nonlinearity of 0.17 LSB and 0.33 LSB, respectively, while its average power consumption is <3.2 mW from a 3 V power supply. It is fabricated using a commercial 0.5 single poly three metal silicon-on-sapphire CMOS process. Autors: Md Tanvir Rahman;Torsten Lehmann; Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs Publication date: Oct 2017, volume: 64, issue:10, pages: 1152 - 1156 Publisher: IEEE
» A Semianalytical Matching Approach for Power Amplifier With Extended Chebyshev Function and Real Frequency Technique
 Abstract:In this paper, an extended Chebyshev function is proposed to adapt the matching condition of the power amplifier (PA) by introducing a new factor. A set of impedance functions can be directly calculated along with the variation of a new variable, and the first element extracted from the functions is distributed in a wide range. In addition, the impedance function whose first element is the closest to the output capacitance of the transistor can be easily read out and selected as the original matching network. The fundamental impedance of the selected function will be reached a good matching state, and the impedances out of band will be on the edge of Smith chart. To achieve better performances, the real frequency technique is applied to adjust the harmonic impedances preventing it from falling into the low-efficiency region. Two PAs with a relative bandwidth of 34% and 75% are implemented to validate the proposed approach. Autors: Zhijiang Dai;Songbai He;Jun Peng;Chaoyi Huang;Weimin Shi;Jingzhou Pang; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Oct 2017, volume: 65, issue:10, pages: 3892 - 3902 Publisher: IEEE
» A Separation Principle for Underactuated Lossless Lagrangian Systems
 Abstract:We study under-actuated Lagrangian systems without dissipative forces, augmented by a chain of integrators. For such systems, we solve the open problem of global tracking control via position measurements only; strictly speaking, we establish uniform global asymptotic stability for the closed loop system. As a corollary, we obtain an original statement for flexible-joint robots, which closes a long-standing open problem of output feedback nonlinear control. Autors: Sofia Avila-Becerril;Antonio Loría;Elena Panteley; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5318 - 5323 Publisher: IEEE
» A Sequential Decomposition Framework and Method for Calibrating Dynamic Origin—Destination Demand in a Congested Network
 Abstract:This paper presents a two-stage model to calibrate the time-dependent, dynamic origin-destination (O–D) demand under congested traffic conditions. The first-stage model estimates O–D trip rates by minimizing link demand deviation with a one-norm formulation approach, so that over the calibration time period, the traffic demand on calibration links matches with the link demand from the field data. Due to its linear model structure, the first-stage model is more computationally effective and solvable on large real-life networks compared with the commonly seen least-square formulation. Then, a time-dependent user equilibrium traffic assignment model is formulated at the second stage to adjust the departure time profile iteratively, aiming to match the calibrated result with the field observed dynamic traffic condition, i.e., time-dependent speed profile. The second-stage model starts from the concept of a demand–capacity–volume relationship at a congested road segment, where demand exceeds supply, and utilizes shockwave theory to capture the differences between true demand and volume output, together with the idea of using travel time propagation between origin and bottleneck locations to infer real demand at the origin location. The two-stage model was implemented and tested in a case study in Tucson, AZ, USA, as an experimental proof of concept, which demonstrated the effectiveness of the proposed calibration framework and method under circumstances, in which the departure time profile was systematically distorted and initial demand solutions deviated from the true O–D matrices. Autors: Xianbiao Hu;Yi-Chang Chiu;Jorge A. Villalobos;Eric Nava; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Oct 2017, volume: 18, issue:10, pages: 2790 - 2797 Publisher: IEEE
» A SiC CMOS Digitally Controlled PWM Generator for High-Temperature Applications
 Abstract:This paper describes a silicon carbide pulse width modulation (PWM) signal generator in the 1.2 μm HiT-SiC CMOS process developed by Raytheon Systems Ltd. The design features a 6-b binary input, which allows for setting a system's duty cycle. The results presented in this paper utilize a field programmable gate array board in the test setup to dynamically set the duty cycle by controlling each bit. A control current is also available to give the user added flexibility for tuning the duty cycle. Experimental results show the duty cycle range of the PWM generator to be between 4.7% and 95.2% at 400°C. Sustained operation of the circuit is demonstrated over a period of 50 h at 300°C. Finally, the PWM generator is evaluated in the operation of a boost converter. Autors: Sajib Roy;Robert C. Murphree;Affan Abbasi;Ashfaqur Rahman;Shamim Ahmed;James Austin Gattis;A. Matt Francis;Jim Holmes;H. Alan Mantooth;Jia Di; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8364 - 8372 Publisher: IEEE
» A SiC Power MOSFET Loss Model Suitable for High-Frequency Applications
 Abstract:The reduced chip size and unipolar current conduction mechanism make silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) suitable for high-frequency power electronics applications. Modeling the switching process of the SiC power MOSFET with parasitic components is important for achieving higher efficiency and power density system design. Therefore, this paper proposes a new concise yet accurate switching loss model for SiC power MOSFETs. Addressing the limitations in experimental measurements, numerical simulations are conducted to validate the proposed model taking the output capacitance Coss discharge and charge into consideration. The role of the parasitic components in the second-order model is discussed in depth for switching losses. Furthermore, this paper also provides guidelines in designing the gate driver for ultrafast SiC power MOSFETs. Autors: Xuan Li;Junning Jiang;Alex Q. Huang;Suxuan Guo;Xiaochuan Deng;Bo Zhang;Xu She; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8268 - 8276 Publisher: IEEE
» A Simple Harmonic Reduction Method in Multipulse Rectifier Using Passive Devices
 Abstract:This paper proposes a novel and passive harmonic reduction method at dc link of multipulse rectifier (MPR). The proposed method uses a single-phase diode-bridge rectifier to generate circulating current, which can shape the input line current of MPR. The input side of the single-phase diode-bridge rectifier is connected with the secondary winding of interphase reactor (IPR), and its output side is connected with load, which can recycle the harmonic energy and feed to load. The operation mode of the single-phase diode-bridge rectifier is analyzed, and the turn ratio of the IPR is designed optimally. Under ideal condition, the proposed MPR operates as a 24-pulse rectifier, and its total harmonic distortion (THD) of input line current is about 7.6%. Most of all, the proposed method is easy to be used in different 12-pulse rectifier topologies, and its conduction losses are far less than that of the conventional double-tapped IPR. Simulation and experiment results show that the THD of input line current is less than 5%. Autors: Fangang Meng;Xiaona Xu;Lei Gao; Appeared in: IEEE Transactions on Industrial Informatics Publication date: Oct 2017, volume: 13, issue:5, pages: 2680 - 2692 Publisher: IEEE
» A Simplified Branch and Bound Approach for Model Predictive Control of Multilevel Cascaded H-Bridge STATCOM
 Abstract:Applying model predictive control (MPC) to cascaded H-bridge multilevel converters, while improving the dynamic performance, suffers from high computation burden due to substantial voltage vectors and switching combinations. In this paper, a simplified branch and bound approach is proposed to reduce the computation of the MPC for a cascaded H-bridge Static Synchronous Compensator (STATCOM). The underlying optimization problem of the current predictive control is a two-variable integer quadratic programming problem. With the proposed approach, the global optimal voltage vector can be selected within linear time instead of polynomial time. This is achieved by selecting the possible values of one variable as the branch, and enumerating the optimal integer results of each branch. The execution time of the proposed approach and conventional methods are compared to demonstrate the effectiveness of the proposed approach. Simulation and experimental results for a seven-level cascaded H-bridge STATCOM system are presented to verify the usability and reliability of the proposed approach. Autors: Yonglei Zhang;XiaoJie Wu;Xibo Yuan; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 7634 - 7644 Publisher: IEEE
» A Simplified Method for Retrieving Aerosol Optical Thickness Using Visibility Data Between 1980 and 2014, A Case Study in China
 Abstract:Analysis of long-term variations of aerosol optical thickness (AOT) is essential to understand the climate change and earth radiation budget. A simplified method was developed in this study to derive the AOT using more than thirty-year surface visibility and aerosol vertical distribution from LiDAR climatology of vertical aerosol structure for space-based LiDAR simulation studies data. Moderate resolution imaging spectroradiometer (MODIS) TERRA and AQUA daily measurements were used to evaluate the performance of the inferred AOT. Results show that the correlations of monthly AOT between MODIS measurements and inferred data are higher than 0.59 and the annual AOT values have stronger correlations (r > 0.82) than monthly data. The inferred AOT can capture the general spatial distribution similar to satellite images with long-term scale. The correlation of seasonal variation between two datasets is also higher than 0.77. The root mean squared error of inferred AOT relative to MODIS AOT is about 0.22 and 0.11 for monthly and yearly data, respectively. Analysis using singular value decomposition shows that the inferred AOT is consistent with MODIS measurements during 2002–2014 spatially and temporally. The average annual AOT in over 200 stations in China between 1980 and 2014 shows generally upward trends. Results from this paper can be used for further analysis of the aerosol effects on climate change in a regional scale. Autors: Zhao Yang Zhang;Man Sing Wong; Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Publication date: Oct 2017, volume: 10, issue:10, pages: 4409 - 4416 Publisher: IEEE
» A Sizing Methodology for Rise-Time Minimization of Dickson Charge Pumps With Capacitive Loads
 Abstract:A novel sizing methodology for Dickson charge pumps with pure capacitive loads is presented. The methodology is based on dynamic analysis to minimize the rise time of the charge pump up to 25% under a given circuit area. The methodology is validated through the implementation of a six-stage charge pump-based driver in 180-nm standard low-voltage CMOS technology. The driver is used for the excitation of ultrasonic transducers with 34 V at a resonance frequency of 220 KHz. A rise time of only 512 nS is achieved. The driver consumes 10.6 mA drawn from a 5-V supply at a pumping frequency of 50 MHz and occupies an area of 0.2 mm2. Autors: Ahmed Saeed;Sameh Ibrahim;Hani Fikry Ragai; Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs Publication date: Oct 2017, volume: 64, issue:10, pages: 1202 - 1206 Publisher: IEEE
» A Solution to Press-Pack Packaging of SiC MOSFETS
 Abstract:This paper proposes a packaging method for SiC MOSFETs that provides a feasible solution of implementing press-pack packaging on SiC MOSFETs to extend the application of SiC devices into the high power range. The challenges in realizing press-pack packaging of SiC MOSFETs are addressed, and the solutions are proposed that fit the specific requirements of SiC MOSFET. To achieve pressure contact on SiC MOSFETs, miniature and flexible press pins called “fuzz buttons” are used in a low-profile interposer to realize die top side connection. Since the press-pack does not provide internal insulation between the active device and the heatsink, the heatsink is included in the power loop. To avoid large parasitic loop inductance being introduced by the heatsinks, a microchannel heatsink is developed which has a low thickness while remaining adequate heat dissipation efficiency. The structure and assembly process flow of the press-pack SiC MOSFET are provided. A half-bridge stack prototype with two press-packs and three heatsinks is developed. The thermal and electrical performances of the press-pack and the half-bridge stack are evaluated by simulations and tests to validate the feasibility of the proposed packaging approach. Autors: Nan Zhu;H. Alan Mantooth;Dehong Xu;Min Chen;Michael D. Glover; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8224 - 8234 Publisher: IEEE
» A Sparse Bayesian Learning Approach for Through-Wall Radar Imaging of Stationary Targets
 Abstract:Through-the-wall radar (TWR) imaging is an emerging technology that enables detection and localization of targets behind walls. In practical operations, TWR sensing faces several technical difficulties including strong wall clutter and missing data measurements. This paper proposes a sparse Bayesian learning (SBL) approach for wall-clutter mitigation and scene reconstruction from compressed data measurements. In the proposed approach, SBL is used to model both the intraantenna signal sparsity and interantenna signal correlation for estimating the antenna signals jointly. Here, the Bayesian framework provides a learning paradigm for sharing measurements among spatial positions, leading to accurate and stable antenna signal estimation. Furthermore, the task of wall-clutter mitigation is formulated as a probabilistic inference problem, where the wall-clutter subspace and its dimension are learned automatically using the mechanism of automatic relevant determination. Automatic discrimination between targets and clutter allows an effective target image formation, which is performed using Bayesian approximation. Experimental results with both real and simulated TWR data demonstrate the effectiveness of the SBL approach in indoor target detection and localization. Autors: Van Ha Tang;Son Lam Phung;Fok Hing Chi Tivive;Abdesselam Bouzerdoum; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2485 - 2501 Publisher: IEEE
» A Sparse Learning Framework for Joint Effect Analysis of Copy Number Variants
 Abstract:Copy number variants (CNVs), including large deletions and duplications, represent an unbalanced change of DNA segments. Abundant in human genomes, CNVs contribute to a large proportion of human genetic diversity, with impact on many human phenotypes. Although recent advances in genetic studies have shed light on the impact of individual CNVs on different traits, the analysis of joint effect of multiple interactive CNVs lags behind from many perspectives. A primary reason is that the large number of CNV combinations and interactions in the human genome make it computationally challenging to perform such joint analysis. To address this challenge, we developed a novel sparse learning framework that combines sparse learning with biological networks to identify interacting CNVs with joint effect on particular traits. We showed that our approach performs well in identifying CNVs with joint phenotypic effect using simulated data. Applied to a real human genomic dataset from the 1,000 Genomes Project, our approach identified multiple CNVs that collectively contribute to population differentiation. We found a set of multiple CNVs that have joint effect in different populations, and affect gene expression differently in distinct populations. These results provided a collection of CNVs that likely have downstream biomedical implications in individuals from diverse population backgrounds. Autors: Zhiyong Wang;Benika Hall;Jinbo Xu;Xinghua Shi; Appeared in: IEEE/ACM Transactions on Computational Biology and Bioinformatics Publication date: Oct 2017, volume: 14, issue:5, pages: 1013 - 1027 Publisher: IEEE
» A Stand-Alone Approach for High-Sensitivity GNSS Receivers in Signal-Challenged Environment
» A State of Charge Estimation Method Based on $H_\infty$ Observer for Switched Systems of Lithium-Ion Nickel–Manganese–Cobalt Batteries
 Abstract:Accurately estimating the state of charge (SOC) of the battery is the basis of battery management system. Based on a linear equivalent circuit model, this paper has introduced a switched battery model to model the complicated physical and chemical reactions properties. The SOC is determined by the battery electromotive force at a present battery state that is estimated through the H∞ switched observer for dealing with the inexact or unknown statistical properties of the modeling and measurement errors. The observer design criterion is presented to ensure the H∞ performance of the switched observer. Then, the proposed method is applied successfully to estimate the SOC by utilizing the current and terminal voltage. Finally, the experimental results have demonstrated that the proposed method can provide high accuracy and robustness for SOC estimation. Autors: Cong-zhi Liu;Qiao Zhu;Liang Li;Wei-qun Liu;Ling-Yan Wang;Neng Xiong;Xiang-yu Wang; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8128 - 8137 Publisher: IEEE
» A Study on Piezoelectric Energy-Harvesting Wireless Sensor Networks Deployed in a Weak Vibration Environment
 Abstract:Wireless sensor network (WSN) is an interestingly promising technology with many applications in intelligent environment-monitoring. Its energy consumption is, however, essentially challenged after it is deployed. In this paper, we developed a low-resonant-frequency piezoelectric energy harvesting device as an alternative to power WSN deployed in a weak vibration environment. An energy management module, equipped with a full-bridge rectifier (FBR), a fully self-powered voltage controller, and a logic-level protection circuit was designed to enable a regulated voltage to intermittently drive WSN for temperature monitoring. The power transfer efficiency of FBR reached 42%, presenting a good performance/cost ratio in the case of a relatively high open-circuit voltage of 8 V and a low rectified voltage of 3.3 V. The experimental results have demonstrated that the proposed WSN was successfully driven at an interval time of less than 1 min, and fully self-powered by the scavenged energy from the environmental vibration source of a 0.15-g acceleration and a 40-Hz vibration frequency. Autors: Yanhui Han;Yue Feng;Zejie Yu;Wenzhong Lou;Huicong Liu; Appeared in: IEEE Sensors Journal Publication date: Oct 2017, volume: 17, issue:20, pages: 6770 - 6777 Publisher: IEEE
» A Subspace Approach to Spectral Quantification for MR Spectroscopic Imaging
 Abstract:Objective: To provide a new approach to spectral quantification for magnetic resonance spectroscopic imaging (MRSI), incorporating both spatial and spectral priors. Methods: A novel signal model is proposed, which represents the spectral distributions of each molecule as a subspace and the entire spectrum as a union of subspaces. Based on this model, the spectral quantification can be solved in two steps: 1) subspace estimation based on the empirical distributions of the spectral parameters estimated using spectral priors; and 2) parameter estimation for the union-of-subspaces model incorporating spatial priors. Results: The proposed method has been evaluated using both simulated and experimental data, producing impressive results. Conclusion: The proposed union-of-subspaces representation of spatiospectral functions provides an effective computational framework for solving the MRSI spectral quantification problem with spatiospectral constraints. Significance: The proposed approach transforms how the MRSI spectral quantification problem is solved and enables efficient and effective use of spatiospectral priors to improve parameter estimation. The resulting algorithm is expected to be useful for a wide range of quantitative metabolic imaging studies using MRSI. Autors: Yudu Li;Fan Lam;Bryan Clifford;Zhi-Pei Liang; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Oct 2017, volume: 64, issue:10, pages: 2486 - 2489 Publisher: IEEE
» A Sugiyama-Like Decoding Algorithm for Convolutional Codes
 Abstract:We propose a decoding algorithm for a class of convolutional codes called skew Reed-Solomon convolutional codes. These are convolutional codes of designed Hamming distance endowed with a cyclic structure yielding a left ideal of a non-commutative ring (a quotient of a skew polynomial ring). In this setting, right and left division algorithms exist, so our algorithm follows the guidelines of the Sugiyama’s procedure for finding the error locator and error evaluator polynomials for Goppa block codes. Autors: José Gómez-Torrecillas;F. J. Lobillo;Gabriel Navarro; Appeared in: IEEE Transactions on Information Theory Publication date: Oct 2017, volume: 63, issue:10, pages: 6216 - 6226 Publisher: IEEE
» A Survey of GNSS-Based Research and Developments for the European Railway Signaling
 Abstract:Railways have already introduced satellite-based localization systems for non-safety related applications. Driven by economic reasons, the use of these systems for new services and, in particular, their introduction in signaling system is seriously investigated today and tested all around the world. Because of the weight of their history, their strong normative context, and the high requested level of safety, the introduction is relatively slow. The aim of this paper is to provide a survey of past and current programs dealing with global navigation satellite systems as a basis to introduce main issues relative to context, standards, performance requirements, and safety proofs. Links with aeronautical concepts are also presented, illustrating the transposable principles and the limits due to the land transport environment. Autors: Juliette Marais;Julie Beugin;Marion Berbineau; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Oct 2017, volume: 18, issue:10, pages: 2602 - 2618 Publisher: IEEE
» A Survey of Train Positioning Solutions
 Abstract:Positioning accurately and safely a train is nowadays a great challenge. That includes currently available railway sensors and new candidate sensors for data fusion. Global Navigation Satellite System and Inertial Measurement Unit sensors arise as prominent technologies to incorporate in railways. Although satellite-based train localization tests can be found in the scientific literature, there are no common criteria to evaluate the performance of the positioning achieved. In this paper, a series of criteria is defined and justified in order to be able to evaluate the most recent and relevant works related to train positioning. The results of this comparative analysis are gathered in tables, where the criteria defined are applied to the works compiled. According to the results obtained, a research gap in safety related applications is found. It is concluded that the economic viability of given solutions should be explored, so as to design an on-board train-integrated positioning system. Autors: Jon Otegui;Alfonso Bahillo;Iban Lopetegi;Luis Enrique Díez; Appeared in: IEEE Sensors Journal Publication date: Oct 2017, volume: 17, issue:20, pages: 6788 - 6797 Publisher: IEEE
» A Survey on Non-Orthogonal Multiple Access for 5G Networks: Research Challenges and Future Trends
 Abstract:Non-orthogonal multiple access (NOMA) is an essential enabling technology for the fifth-generation (5G) wireless networks to meet the heterogeneous demands on low latency, high reliability, massive connectivity, improved fairness, and high throughput. The key idea behind NOMA is to serve multiple users in the same resource block, such as a time slot, subcarrier, or spreading code. The NOMA principle is a general framework, and several recently proposed 5G multiple access schemes can be viewed as special cases. This survey provides an overview of the latest NOMA research and innovations as well as their applications. Thereby, the papers published in this special issue are put into the context of the existing literature. Future research challenges regarding NOMA in 5G and beyond are also discussed. Autors: Zhiguo Ding;Xianfu Lei;George K. Karagiannidis;Robert Schober;Jinhong Yuan;Vijay K. Bhargava; Appeared in: IEEE Journal on Selected Areas in Communications Publication date: Oct 2017, volume: 35, issue:10, pages: 2181 - 2195 Publisher: IEEE
» A Switched Reluctance Motor Drive Using Photovoltaic Transistors: Principle, Prototype, Experimental, and Numerical Results
 Abstract:A solar-powered switch reluctance motor drive using photovoltaic transistors (PVTs) is presented. The expression “PVT” is used to designate a conventional photovoltaic (PV) cell used as a light-controlled power transistor. To obtain a motor drive, a set of PVTs controls the current fed from an external dc power source to the motor phases. The control is achieved by modulating the sunlight hitting the PVTs using a shutter driven by the motor rotor. If the external dc source is a solar panel, the resulting system is able to convert light energy into mechanical energy, without the need of any brushes or other power electronics components. This system could be more affordable and reliable than conventional ones, and therefore, is well suited for off-grid applications like water pumping. This paper first discusses the operation of a PVT through the proposition and the validation of a model. Then, the operating principle of a PVT inverter is clarified. Finally, experimental and numerical results on the first PVT inverter-fed switched reluctance motor are reported. A prototype was built using a switched reluctance motor 6/4 and 12 PVTs. It was here connected to an external 12 V dc power source as a step before using a solar PV source. Results that the PVT inverter-fed switched reluctance motor was operating as expected and provided useful power. Autors: Loïc Quéval;Alain Coty;Lionel Vido;Raimund Gottkehaskamp;Bernard Multon; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4886 - 4893 Publisher: IEEE
» A Tale of Ten Cities: Characterizing Signatures of Mobile Traffic in Urban Areas
 Abstract:Urban landscapes present a variety of socio-topological environments that are associated to diverse human activities. As the latter affect the way individuals connect with each other, a bound exists between the urban tissue and the mobile communication demand. In this paper, we investigate the heterogeneous patterns emerging in the mobile communication activity recorded within metropolitan regions. To that end, we introduce an original technique to identify classes of mobile traffic signatures that are distinctive of different urban fabrics. Our proposed technique outperforms previous approaches when confronted to ground-truth information, and allows characterizing the mobile demand in greater detail than that attained in the literature to date. We apply our technique to extensive real-world data collected by major mobile operators in 10 cities. Results unveil the diversity of baseline communication activities across countries, but also provide evidence of the existence of a number of mobile traffic signatures that are common to all studied areas and specific to particular land uses. Autors: Angelo Furno;Marco Fiore;Razvan Stanica;Cezary Ziemlicki;Zbigniew Smoreda; Appeared in: IEEE Transactions on Mobile Computing Publication date: Oct 2017, volume: 16, issue:10, pages: 2682 - 2696 Publisher: IEEE
» A Technique for Efficient Query Estimation over Distributed Data Streams
 Abstract:Distributed data stream mining in a sliding window has emerged recently, due to its applications in many domains including large Telecoms and Internet Service Providers, financial tickers, ATM and credit card operations in banks and transactions in retail chains. Many of these large-scale applications prohibit monitoring data centrally at a single location due to their massive volume of the data; therefore, data acquisition, processing, and mining tasks are often distributed to a number of processing nodes, which monitor their local streams and exchange only the summary of data either periodically or on demand. While this offer many advantages, distributed stream applications possess significant challenges including problems related to an online analysis of the recent data, communication efficiency and various estimation of various complex queries. There are few existing techniques which solve problems related to distributed sliding window data stream; however, those techniques are focused on solving only simple problems and require high space, query, and communication cost, which can be a bottleneck for many of these large scale applications. In this paper, we propose an efficient query estimation technique by constructing a small sketch of the data stream. The constructed sketch uses a deterministic sliding window model and can estimate various complex queries, for both centralized and distributed applications; including point queries (i.e., range queries and heavy hitter queries), quantiles, inner product, and self-join size queries, with deterministic guarantees on the precision. The proposed approach improves upon recent existing work for these problems, in terms of the memory and query cost in a centralized setting and in terms of communication cost and merge complexity in a distributed setting. It requires memory (where is a user defined parameter), can provide estimates in time, and processes each incoming record in amortized time. Detailed experimental analysis, both in centralized and distributed settings demonstrates that in practice the proposed approach uses about six times less memory, and has about eight times less query time when compared to ECM sketches. In a distributed application, the proposed technique also significantly improves (around seven times) on the communication cost between distributed sites. Autors: Zubair Shah;Abdun Naser Mahmood;Zahir Tari;Albert Y. Zomaya; Appeared in: IEEE Transactions on Parallel and Distributed Systems Publication date: Oct 2017, volume: 28, issue:10, pages: 2770 - 2783 Publisher: IEEE
» A Thermal Ink-Jet Printer Head Prototype With Full Carbon Based Microbubble Generator
 Abstract:This paper presents the development of a novel thermal ink-jet printer head prototype using full carbon-based microbubble generators with carbon nanotubes as heating elements and graphene as electrodes. Meanwhile, each microbubble generator is equipped with a carbon nanotube sensor to real-timely probe the temperature of its surrounding micro-environment. With an array of microbubble generators and sensors fabricated on quartz glass, as well as a microfluidic structure constructed by the micromachined silicon, the printer head prototype is formed by an anodic silicon-glass bonding process with several scattered graphene film flakes as medium. Droplet ejection with volume as tiny as ~0.03 pl corresponding to a very high spatial resolution of >2000 dpi driven by two microbubble valves is demonstrated by the printing unit in the prototype. Increasing the input power cannot only speed up the bubble nucleation and growth, but also improve the utilizing efficiency of electric heating energy. The experimental detected temperature variation in the printing unit reveals its nonlinear heat convection property by comparison with the theoretical calculation by finite-element analysis. [2017-0048] Autors: Yunhong Xiang;Lvhui Jiang;Yu Zhu;Changsheng Chen;Yangyang Chen;Wenli Zhou; Appeared in: Journal of Microelectromechanical Systems Publication date: Oct 2017, volume: 26, issue:5, pages: 1040 - 1046 Publisher: IEEE
» A Tight Upper Bound on the Second-Order Coding Rate of the Parallel Gaussian Channel With Feedback
 Abstract:This paper investigates the asymptotic expansion for the maximum rate of fixed-length codes over a parallel Gaussian channel with feedback under the following setting: a peak power constraint is imposed on every transmitted codeword, and the average error probabilities of decoding the transmitted message are non-vanishing as the blocklength increases. The main contribution of this paper is a self-contained proof of an upper bound on the first- and second-order asymptotics of the parallel Gaussian channel with feedback. The proof techniques involve developing an information spectrum bound followed by using Curtiss’ theorem to show that a sum of dependent random variables associated with the information spectrum bound converges in distribution to a sum of independent random variables, thus facilitating the use of the usual central limit theorem. Combined with existing achievability results, our result implies that the presence of feedback does not improve the first- and second-order asymptotics. Autors: Silas L. Fong;Vincent Y. F. Tan; Appeared in: IEEE Transactions on Information Theory Publication date: Oct 2017, volume: 63, issue:10, pages: 6474 - 6486 Publisher: IEEE
» A TLM-Based Wideband Adjoint Variable Method for Sensitivity Analysis of Non-Dispersive Anisotropic Structures
 Abstract:We propose a wideband theory for adjoint variable sensitivity analysis of problems with non-dispersive anisotropic materials. The method is developed based on the transmission line modeling (TLM) technique. The anisotropic material property can be the full tensors of permittivity, permeability, electrical conductivity, magnetic resistivity, magnetoelectric coupling, or electromagnetic coupling. The tensors are assumed constant and may contain non-diagonal elements. Our algorithm estimates the gradient of the desired response with respect to all the designable parameters using at most one extra simulation, regardless of the number of parameters. The theory has been implemented in an algorithm for 2-D and 3-D structures. Our estimated sensitivities match well the computationally expensive central finite difference approximations. Autors: Laleh Seyyed Kalantari;Osman S. Ahmed;Mohamed H. Bakr;Natalia K. Nikolova; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5267 - 5278 Publisher: IEEE
» A Trust Label System for Communicating Trust in Cloud Services
 Abstract:Cloud computing is rapidly changing the digital service landscape. A proliferation of Cloud providers has emerged, increasing the difficulty of consumer decisions. Trust issues have been identified as a factor holding back Cloud adoption. The risks and challenges inherent in the adoption of Cloud services are well recognised in the computing literature. In conjunction with these risks, the relative novelty of the online environment as a context for the provision of business services can increase consumer perceptions of uncertainty. This uncertainty is worsened in a Cloud context due to the lack of transparency, from the consumer perspective, into the service types, operational conditions and the quality of service offered by the diverse providers. Previous approaches failed to provide an appropriate medium for communicating trust and trustworthiness in Clouds. A new strategy is required to improve consumer confidence and trust in Cloud providers. This paper presents the operationalisation of a trust label system designed to communicate trust and trustworthiness in Cloud services. We describe the technical details and implementation of the trust label components. Based on a use case scenario, an initial evaluation was carried out to test its operations and its usefulness for increasing consumer trust in Cloud services. Autors: Vincent C. Emeakaroha;Kaniz Fatema;Lisa van der Werff;Philip Healy;Theo Lynn;John P. Morrison; Appeared in: IEEE Transactions on Services Computing Publication date: Oct 2017, volume: 10, issue:5, pages: 689 - 700 Publisher: IEEE
» A Two-Level Game Theory Approach for Joint Relay Selection and Resource Allocation in Network Coding Assisted D2D Communications
 Abstract:Device-to-device (D2D) communication, which enables direct transmissions between mobile devices to improve spectrum efficiency, is one of the preferable candidate technologies for the next generation cellular network. Network coding, on the other hand, is widely used to improve throughput in ad hoc networks. Thus, the performance of D2D communications in cellular networks can potentially benefit from network coding. Aiming to improve the achievable capacity of D2D communications, we propose a system with inter-session network coding enabled to assist D2D transmissions. We formulate the joint problem of relay selection and resource allocation in network coding assisted D2D communications, and obtain the overall capacity of the network under complex interference conditions as a function of the relay selection and resource allocation. To solve the formulated problem, we propose a two-level decentralized approach termed NC-D2D, which solves the relay selection and resource allocation problems alternatively to obtain stable solutions for these two problems. Specifically, a coalition formation game associates relays with D2D pairs to enable network coding aided transmissions, and a greedy algorithm based game allocates limited cellular resources to D2D pairs and relays in NC-D2D, respectively. The performances of the proposed scheme is evaluated through extensive simulations to prove its superiority. Autors: Chuhan Gao;Yong Li;Yulei Zhao;Sheng Chen; Appeared in: IEEE Transactions on Mobile Computing Publication date: Oct 2017, volume: 16, issue:10, pages: 2697 - 2711 Publisher: IEEE
» A Two-Line Time-Domain Gating Method for Characterization of Test Fixture With via Hole Discontinuity
 Abstract:The time-domain gating method (TGM) is an accurate and useful method to characterize the test fixtures used in the measurement of high-speed connectors. However, its accuracy can be degraded by the gating error when the test fixture contains the impedance discontinuity near the fixture end facing the device under test. To overcome this limitation, this letter proposes a two-line TGM (2LTGM) for characterizing the test fixtures having the discontinuities such as via holes. The proposed method does not require any modification of the test fixtures with the help of the proposed test structures and T-parameter extraction procedure. The experimental results show that the proposed 2LTGM has an 8 dB lower mean square error than the conventional TGM for the test fixtures having via hole discontinuities at the end. We expect that the 2LTGM can improve the accuracy for characterizing the test fixtures with any discontinuities not limited to the via holes. Autors: Jaeyong Cho;Byung-Sung Kim;Jonghyuck Jeong;Junseong Kim;Kibeom Kim;Karam Hwang;Hwiseob Lee;Seungil Jeung;Seungyoung Ahn; Appeared in: IEEE Microwave and Wireless Components Letters Publication date: Oct 2017, volume: 27, issue:10, pages: 936 - 938 Publisher: IEEE
» A Unification of Intuitionistic Fuzzy Calculus Theories Based on Subtraction Derivatives and Division Derivatives
 Abstract:Intuitionistic fuzzy calculus replaces real numbers in classical calculus with intuitionistic fuzzy numbers that are the basic elements of Atanassov's intuitionistic fuzzy sets. Intuitionistic fuzzy calculus consists of two parallel parts, which are respectively developed based on the subtraction derivatives and the division derivatives. This paper focuses on building the relationships between the two independent intuitionistic fuzzy calculus theories, and unifying them into a whole theory. Autors: Qian Lei;Zeshui Xu; Appeared in: IEEE Transactions on Fuzzy Systems Publication date: Oct 2017, volume: 25, issue:5, pages: 1023 - 1040 Publisher: IEEE
» A Unified Framework for Deterministic and Probabilistic $\mathscr {D}$-Stability Analysis of Uncertain Polynomial Matrices
 Abstract:In control theory, we are often interested in robust -stability analysis, which aims at verifying if all the eigenvalues of an uncertain matrix lie in a given region . Although many algorithms have been developed to provide conditions for an uncertain matrix to be robustly -stable, the problem of computing the probability of an uncertain matrix to be -stable is still unexplored. The goal of this paper is to fill this gap in two directions. First, the only constraint on the stability region that we impose is that its complement is a semialgebraic set. This comprises many important cases in robust control theory. Second, the -stability analysis problem is formulated in a probabilistic framework, by assuming that only few probabilistic information is available on the uncertain parameters, such as support and some moments. We will show how to compute the minimum probability that the matrix is -stable by using convex relaxations based on the theory of moments. Autors: Dario Piga;Alessio Benavoli; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5437 - 5444 Publisher: IEEE
» A Versatile and Accurate Compact Model of Memristor With Equivalent Resistor Topology
 Abstract:Memristor appeals to a wide research field as the fourth passive element, and its model has been a necessary topic for future circuit applications. In this letter, a novel compact model of memristor, based on the equivalent resistor topology of variable conductive filaments, is presented. Since the formation and annihilation of conductive filaments is a natural mechanism of mainstream memristor, the model is essential and so more accurate than those nonlinear dopant drift models. On the other hand, the equivalent resistor idea makes our model versatile and efficient comparing with some complex physical process methods, and fulfills the requirements of circuit design. The versatility and accuracy of our compact model have been verified by the results that it can reduce at least 30% error in a Pt/TiO2/TiO2+x/Pt type memristor and at least 20% error in a Ta/TaOx/Pt type memristor, comparing with some popular models. Moreover it is easier to be implemented in Verilog-A, which possesses more flexibility and higher applicability in circuit design. Autors: Ruohua Zhu;Sheng Chang;Hao Wang;Qijun Huang;Jin He;Fan Yi; Appeared in: IEEE Electron Device Letters Publication date: Oct 2017, volume: 38, issue:10, pages: 1367 - 1370 Publisher: IEEE
» A Versatile Noise Performance Metric for Electrical Impedance Tomography Algorithms
 Abstract:Electrical impedance tomography (EIT) is an emerging technology for real-time monitoring of patients under mechanical ventilation. EIT has the potential to offer continuous medical monitoring while being noninvasive, radiation free, and low cost. Due to their ill-posedness, image reconstruction typically uses regularization, which implies a hyperparameter controlling the tradeoff between noise rejection and resolution or other accuracies. In order to compare reconstruction algorithms, it is common to choose hyperparameter values such that the reconstructed images have equal noise performance (NP), i.e., the amount of measurement noise reflected in the images. For EIT many methods have been suggested, but none work well when the data originate from different measurement setups, such as for different electrode positions or measurement patterns. To address this issue, we propose a new NP metric based on the average signal-to-noise ratio in the image domain. The approach is validated for EIT using simulation experiments on a human thorax model and measurements on a resistor phantom. Results show that the approach is robust to the measurement configuration (i.e., number and position of electrodes, skip pattern) and the reconstruction algorithm used. We propose this novel approach as a way to select optimized measurement configurations and algorithms. Autors: Fabian Braun;Martin Proença;Josep Solà;Jean-Philippe Thiran;Andy Adler; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Oct 2017, volume: 64, issue:10, pages: 2321 - 2330 Publisher: IEEE
» A Wafer Prealignment Algorithm Based on Fourier Transform and Least Square Regression
 Abstract:Automatic wafer prealignment is an important process in wafer manufacturing, whereby its flat edge is set at a predefined angle and its center is set in a predefined position; translational and rotational movement compensate for deviation of the wafer. However, as the traditional wafer prealignment algorithm depends on marked templates at the training stage when the type of wafer is changed, the templates need to be retrained. This paper proposes a new wafer prealignment algorithm, based on Fourier transform for orientation prealignment and least square regression for position prealignment, which will automatically adapt to different types of wafers in 2-D space. Results from experiments with the proposed algorithm on a laser-scribing machine using two types of wafer show that the orientation prealignment achieved an accuracy of 0.05°, the position prealignment achieved an accuracy of 5 pixels, and the average operation time was approximately 1.5 s. As prealignment algorithm therefore meets real-time efficiency and precision requirements, it is suitable for use with semiconductor devices.Note to Practitioners—Because deviation appears when a wafer is first put on the working table, the traditional process is to set up a prealignment system when aligning a new type of wafer. However, different templates increase difficulty for machine operators, and decrease automation and reliability of the devices. This paper therefore proposes a new general prealignment algorithm based on using Fourier transform for orientation prealignment and least square regression for position prealignment. The algorithm was tested on two types of wafer with results showing that the orientation prealignment achieved an accuracy of 0.05°, the position prealignment achieved an accuracy of 5 pixels, and the average operation time was about 1.5 s, all of which meet real-time requirements. Although the alg- rithm can be adapted to different wafers without adjustment, it does not fit nonquadrilateral chips very well. Accordingly, we will develop an improved algorithm with better generality in due course. Autors: Jiayu Xu;Hong Hu;Yulin Lei;Huaiyuan Liu; Appeared in: IEEE Transactions on Automation Science and Engineering Publication date: Oct 2017, volume: 14, issue:4, pages: 1771 - 1777 Publisher: IEEE
» A Wideband Bandpass Filter With Reconfigurable Bandwidth Based on Cross-Shaped Resonator
 Abstract:A wideband bandpass filter (BPF) with reconfigurable bandwidth (BW) is proposed based on a parallel-coupled line structure and a cross-shaped resonator with open stubs. The p-i-n diodes are used as the tuning elements, which can implement three reconfigurable BW states. The prototype of the designed filter reports an absolute BW tuning range of 1.22 GHz, while the fractional BW is varied from 34.8% to 56.5% when centered at 5.7 GHz. The simulation and measured results are in good agreement. Comparing with previous works, the proposed reconfigurable BPF features wider BW tuning range with maximum number of tuning states. Autors: Teng Cheng;Kam-Weng Tam; Appeared in: IEEE Microwave and Wireless Components Letters Publication date: Oct 2017, volume: 27, issue:10, pages: 909 - 911 Publisher: IEEE
» Absolute Electroluminescence Imaging Diagnosis of GaAs Thin-Film Solar Cells
 Abstract:A spatially resolved absolute electroluminescence (EL) imaging method was utilized to analyze the photovoltaic properties and resistive loss properties of a GaAs thin-film solar cell. The I–V relation was extrapolated from the absolute EL efficiency measurements in conjunction with the external-quantum-efficiency (EQE) measurements; the EL extrapolated I–V relation has a merit over the conventional I–V relation measured with a solar simulator that it could eliminate the series resistance effect caused by external probe contact. Then, the mapping of the internal voltage of the solar cell and the sheet resistance of the window layer of the solar cell were obtained from the calibrated absolute EL imaging method. Finally, optic electroconversion losses of the solar cell including radiative loss, nonradiative loss, thermalization loss, transmission loss, and junction loss were quantified given by the EL and EQE measurements. Autors: XiaoBo Hu;Tengfei Chen;Juanjuan Xue;Guoen Weng;Shaoqiang Chen;Hidefumi Akiyama;Ziqiang Zhu; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 9 Publisher: IEEE
» AC-Inductors Design for a Modular Multilevel TSBC Converter, and Performance of a Low-Speed High-Torque Motor Drive Using the Converter
 Abstract:This paper provides a theoretical and experimental discussion on ac-inductors design for a modular multilevel triple-star bridge-cells (TSBC) converter, or shortly a TSBC converter. This converter requires multiple ac inductors for controlling nine cluster currents. This paper proposes three three-legged, six-winding, “interzigzag” inductors for the TSBC converter. Since each leg of the individual inductor has two windings, the three inductors have 18 windings in total. The wire leads are zigzagged among the three inductors. This unique structure of the “interzigzag” windings leads to the following feature: Both three-phase supply and motor currents produce no magnetic flux in each of the nine legs. This feature makes each inductor smaller in size and lighter in weight. A specially-designed downscaled motor-drive system rated at 400 V and 15 kW is constructed and tested to confirm the validity of a design of the proposed inductors, as well as to verify transient motor-drive performance during four-quadrant operation. Autors: Wataru Kawamura;Makoto Hagiwara;Hirofumi Akagi;Masahiko Tsukakoshi;Ritaka Nakamura;Sumiyasu Kodama; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4718 - 4729 Publisher: IEEE
» Accelerating Recurrent Neural Networks: A Memory-Efficient Approach
 Abstract:Recurrent neural networks (RNNs) have achieved the state-of-the-art performance on various sequence learning tasks due to their powerful sequence modeling capability. However, RNNs usually require a large number of parameters and high computational complexity. Hence, it is quite challenging to implement complex RNNs on embedded devices with stringent memory and latency requirement. In this paper, we first present a novel hybrid compression method for a widely used RNN variant, long–short term memory (LSTM), to tackle these implementation challenges. By properly using circulant matrices, forward nonlinear function approximation, and efficient quantization schemes with a retrain-based training strategy, the proposed compression method can reduce more than 95% of memory usage with negligible accuracy loss when verified under language modeling and speech recognition tasks. An efficient scalable parallel hardware architecture is then proposed for the compressed LSTM. With an innovative chessboard division method for matrix–vector multiplications, the parallelism of the proposed hardware architecture can be freely chosen under certain latency requirement. Specifically, for the circulant matrix–vector multiplications employed in the compressed LSTM, the circulant matrices are judiciously reorganized to fit in with the chessboard division and minimize the number of memory accesses required for the matrix multiplications. The proposed architecture is modeled using register transfer language (RTL) and synthesized under the TSMC 90-nm CMOS technology. With 518.5-kB on-chip memory, we are able to process a compressed LSTM in 1.71 , corresponding to 2.46 TOPS on the uncompressed one, at a cost of 30.77-mm2 chi- area. The implementation results demonstrate that the proposed design can achieve significantly high flexibility and area efficiency, which satisfies many real-time applications on embedded devices. It is worth mentioning that the memory-efficient approach of accelerating LSTM developed in this paper is also applicable to other RNN variants. Autors: Zhisheng Wang;Jun Lin;Zhongfeng Wang; Appeared in: IEEE Transactions on Very Large Scale Integration Systems Publication date: Oct 2017, volume: 25, issue:10, pages: 2763 - 2775 Publisher: IEEE
» Acceleration of the WRF Monin–Obukhov–Janjic Surface Layer Parameterization Scheme on an MIC-Based Platform for Weather Forecast
 Abstract:A state-of-the-art numerical weather prediction (NWP) model, comprising weather research and forecast (WRF) model and analysis techniques, has been extensively exercised for weather prophecy all over the world. The WRF model, the soul role in NWP, constitutes dynamic solvers and elaborate physical components for conducting fluid behavior, all of which are sketched for both atmospheric research analyses and operational weather foretell. One salient physical ingredient in WRF is the surface layer simulation, which provides surface heat and moisture fluxes through calculation of surface friction velocities and exchange coefficients. The Monin–Obukhov–Janjic (MOJ) scheme is one popular surface layer option in WRF. This is one of the schemes in WRF we choose to expedite toward an end-to-end accelerated weather model. One advantageous aspect in WRF is the independence among grid points that facilitates programming implementations in parallel computation. We here present a parallel construction on the MOJ module with application of vectorization elements and efficient parallelization essentials furnished by Intel many integrated core (MIC) architecture. To achieve high computing performance, apart from the fundamental usage of Intel MIC architecture, this paper offers some new approaches related to code structure and art of optimization skills. At the end, in comparison with the original code separately executing on one CPU core and on one CPU socket (eight cores) with Intel Xeon E5-2670, the optimized MIC-based MOJ module running on Xeon Phi coprocessor 7120P ameliorates the computing performance by 9.6× and 1.5×, respectively. Autors: Melin Huang;Bormin Huang;Hung-Lung Allen Huang; Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Publication date: Oct 2017, volume: 10, issue:10, pages: 4399 - 4408 Publisher: IEEE
» Accuracy of Range-Based Cooperative Positioning: A Lower Bound Analysis
 Abstract:Accurate location information is essential for mobile systems such as wireless sensor networks. A location-aware sensor network generally includes two types of nodes: Sensors whose locations to be determined and anchors whose locations are known a priori. For range-based cooperative positioning, sensors’ locations are deduced from anchor-to-sensor and sensor-to-sensor range measurements. Positioning accuracy depends on the network parameters such as network connectivity and size. This paper provides a generalized theory that quantitatively characterizes such a relation between network parameters and positioning accuracy. We use the average degree as a connectivity metric and use geometric dilution of precision (DOP) to quantify positioning accuracy. Under the assumption that nodes are randomly deployed, we prove a novel lower bound on expectation of average geometric DOP (LB-E-AGDOP) and derives a closed-form formula that relates LB-E-AGDOP to only three parameters: Average anchor degree, average sensor degree, and number of sensor nodes. The formula shows that positioning accuracy is approximately inversely proportional to the average degree, and a higher ratio of average anchor degree to average sensor degree yields better positioning accuracy. Furthermore, the paper shows a strong connection between LB-E-AGDOP and the best achievable accuracy. Finally, we demonstrate the theory via numerical simulations with three different random graph models. Autors: Liang Heng;Grace Xingxin Gao; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2304 - 2316 Publisher: IEEE
» Accuracy-Aware Power Management for Many-Core Systems Running Error-Resilient Applications
 Abstract:Power capping techniques based on dynamic voltage and frequency scaling (DVFS) and power gating (PG) are oriented toward power actuation, compromising on performance and energy. Inherent error resilience of emerging application domains, such as Internet-of-Things (IoT) and machine learning, provides opportunities for energy and performance gains. Leveraging accuracy-performance tradeoffs in such applications, we propose approximation (APPX) as another knob for close-looped power management, to complement power knobs with performance and energy gains. We design a power management framework, APPEND+, that can switch between accurate and approximate modes of execution subject to system throughput requirements. APPEND+ considers the sensitivity of the application to error to make disciplined alteration between levels of APPX such that performance is maximized while error is minimized. We implement a power management scheme that uses APPX, DVFS, and PG knobs hierarchically. We evaluated our proposed approach over machine learning and signal processing applications along with two case studies on IoT—early warning score system and fall detection. APPEND+ yields higher throughput, improved latency up to five times, better performance per energy, and dark silicon mitigation compared with the state-of-the-art power management techniques over a set of applications ranging from high to no error resilience. Autors: Anil Kanduri;Mohammad-Hashem Haghbayan;Amir M. Rahmani;Pasi Liljeberg;Axel Jantsch;Hannu Tenhunen;Nikil Dutt; Appeared in: IEEE Transactions on Very Large Scale Integration Systems Publication date: Oct 2017, volume: 25, issue:10, pages: 2749 - 2762 Publisher: IEEE
» Accuracy-Enhanced Algorithms for the Slot Leakage Inductance Computation of Double-Layer Windings
 Abstract:The paper presents original developments concerning the analytical computation of the slot leakage inductive parameters referring to unsaturated rotating electrical machines. In particular, the double-layer winding layout and arbitrary-shaped semi-closed slots are considered. The conventional analytical formulations of the self- and mutual-inductances of the two layers are initially presented, together with the algorithm developed for their computations. Then, the error causes laying on the simplifying assumptions are discussed and two corrections are applied to the conventional equations to enhance their accuracy with respect to finite element method estimations. Numerical examples of the magnetic energy stored in several slot geometrical domains are included in order to show the potentialities of the proposed analytical approach. Autors: Andrea Cavagnino; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4422 - 4430 Publisher: IEEE
» Accurate and Efficient Approximation of Clothoids Using Bézier Curves for Path Planning
 Abstract:An accurate and efficient clothoid approximation approach is presented in this paper using Bézier curves based on the minimization of curvature profile difference. Compared with existing methods, the proposed approach is able to guarantee higher order geometric continuity with smaller approximation error in terms of position, orientation, and curvature. The approximation scheme takes place in three stages. First, a subset of clothoids with specific winding angle constraints referred to as elementary clothoids is approximated using quintic Bézier curves. Then, a basic clothoid defined in the first quadrant is formulated, which is composed of a series of transformed elementary clothoids. An adaptive sampling stra-tegy is applied to ensure that the resulting Bézier segments are computed within a specified accuracy and all the required information can be obtained offline and stored in a lookup table. Finally, a general clothoid with arbitrary parameters can be conveniently approximated based on the lookup table through appropriate geometric transformations. A comparison with the recent circular interpolation and rational Bézier curve based approximation shows that the proposed approach is able to achieve equivalent or greater computational efficiency in most scenarios. Autors: Yong Chen;Yiyu Cai;Jianmin Zheng;Daniel Thalmann; Appeared in: IEEE Transactions on Robotics Publication date: Oct 2017, volume: 33, issue:5, pages: 1242 - 1247 Publisher: IEEE
» Accurate Closed-Form Expressions for the Bit Rate-Wireless Transmission Distance Relationship in IR-UWBoF Systems
 Abstract:Efficient utilization of the extremely limited available power of impulse radio ultrawideband (IR-UWB) waveforms can significantly extend their wireless reach in the wireless transmission chain of IR-UWB over fiber (IR-UWBoF) systems. In this letter, the two most common types of photonically generated IR-UWB waveforms are considered and accurate closed-form analytical expressions for the bit rate—distance relationship in the wireless transmission chain of IR-UWBoF systems are developed. These analytical expressions are verified by simulations and optimized such that the wireless transmission distance of IR-UWB waveforms is maximized under the Federal Communications Commission spectral constraints. Autors: Mohamed Shehata;Hassan Mostafa;Yehea Ismail; Appeared in: IEEE Communications Letters Publication date: Oct 2017, volume: 21, issue:10, pages: 2138 - 2141 Publisher: IEEE
» Accurate Insect Orientation Extraction Based on Polarization Scattering Matrix Estimation
 Abstract:A novel insect orientation extraction method is proposed based on the target polarization scattering matrix (PSM) estimation, which is applicable for traditional vertical-looking insect radar with noncoherent reception as well as the coherent radar. The insect echo signal at different polarization directions on the radar polarization plane is usually acquired by means of rotating linearly polarized antenna. In this letter, the insect echo signal is first used to accurately estimate insect PSM by an iterative algorithm based on the second-order polynomial approximation. Meanwhile, the Cramer–Rao lower bound is also analyzed to test the estimation performance. Next, based on the assumption that the target orientation is consistent with the dominant eigenvector, the insect orientation is extracted from the estimated PSM. Finally, both theoretical simulations and real experimental data are used to validate the effectiveness and feasibility of our proposed method, which can achieve good orientation estimation accuracy at low signal-to-noise ratio. Autors: C. Hu;W. Li;R. Wang;C. Liu;T. Zhang;W. Li; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Oct 2017, volume: 14, issue:10, pages: 1755 - 1759 Publisher: IEEE
» Accurate Reduced Dimensional Polynomial Chaos for Efficient Uncertainty Quantification of Microwave/RF Networks
 Abstract:This paper presents a polynomial chaos (PC) formulation based on the concept of dimension reduction for the efficient uncertainty analysis of microwave and RF networks. This formulation exploits a high-dimensional model representation for quantifying the relative effect of each random dimension on the network responses surface. This information acts as problem-dependent sensitivity indices guiding the intelligent identification and subsequent pruning of the statistically unimportant random dimensions from the original parametric space. Performing a PC expansion in the resultant low-dimensional random subspace leads to the recovery of a sparser set of coefficients than that obtained from the full-dimensional random space with negligible loss in accuracy. Novel methodologies to reuse the preliminary PC bases and SPICE simulations required to estimate the sensitivity indices are presented, thereby making the proposed approach more efficient and accurate than standard sparse PC approaches. The validity of the proposed approach is demonstrated using three distributed network examples. Autors: Aditi Krishna Prasad;Sourajeet Roy; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Oct 2017, volume: 65, issue:10, pages: 3697 - 3708 Publisher: IEEE
» Accurate Solution of Electromagnetic Scattering by Super-Thin Conducting Objects Based on Magnetic Field Integral Equation
 Abstract:Electromagnetic scattering by super-thin conducting objects is formulated by integral equation approach. It could be difficult to obtain accurate solutions for such a problem because the current density changes dramatically near the edges of such objects and many low-quality meshes exist on the side faces of objects when discretized. Traditionally, the electric field integral equation is used to describe the problem and the three-dimensional (3-D) objects are approximated as a two-dimensional (2-D) open structure with a summation of the current density at two opposite sides. In this communication, the magnetic field integral equation (MFIE) is employed to govern the problem and the super-thin objects are strictly treated as 3-D objects. The MFIE is a second-kind integral equation resulting in a better conditioning and can also release the low-frequency breakdown problem, but it has not been applied to very thin structures. In the method of moments solution, a robust near-singularity treatment for its kernel is developed based on the Green’s lemma. The derived formulations are friendly and very suitable for low-quality triangular meshes. Numerical examples are presented to demonstrate the scheme and good results have been obtained. Autors: Mei Song Tong;Xiao Jia Huang; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5633 - 5638 Publisher: IEEE
» Achievable DoF Regions of MIMO Networks With Imperfect CSIT
 Abstract:We focus on a two-receiver multiple-input-multiple-output (MIMO), broadcast channel (BC), and interference channel (IC) with an arbitrary number of antennas at each node. We assume an imperfect knowledge of local channel state information at the transmitters, whose error decays with the signal-to-noise-ratio. With such configuration, we characterize the achievable degrees-of-freedom (DoF) regions in both BC and IC, by proposing a rate-splitting (RS) approach, which divides each receiver’s message into a common part and a private part. Compared with the RS scheme designed for the symmetric MIMO case, the novelties of the proposed block lie in: 1) delivering additional non-ZF-precoded private symbols to the receiver with the greater number of antennas and 2) a space-time implementation. These features provide more flexibilities in balancing the common-message-decodabilities at the two receivers, and fully exploit asymmetric antenna arrays. Besides, in IC, we modify the power allocation designed for the asymmetric BC based on the signal space, where the two transmitted signals interfere with each other. We also derive an outer-bound for the DoF regions and show that the proposed achievable DoF regions are optimal under some antenna configurations and channel state information at the transmitter side qualities. Autors: Chenxi Hao;Borzoo Rassouli;Bruno Clerckx; Appeared in: IEEE Transactions on Information Theory Publication date: Oct 2017, volume: 63, issue:10, pages: 6587 - 6606 Publisher: IEEE
» Acoustical Streaming in Microfluidic CMUT Integrated Chip Controls the Biochemical Interaction Rate
 Abstract:Acoustical fluid mixing and streaming in microfluidic chips enhance the detection and fluid routeing capabilities in the lab-on-chip devices. Capacitive micromachined ultrasound transducers (CMUT) are easy to integrate into a closely packed environment, and they can be simultaneously used as integrated sensors and micropumps/mixers. In this paper, particular focus is given to examininge the impact of the acoustical fluid mixing to the kinetics of biochemical interaction. CMUT interdigital transducers for 10-MHz operation in water were designed and fabricated using the surface micromachining technique. Devices use Scholte type waves for biochemical detection and acoustical streaming. They also have the ability to control the directionality of acoustical streaming by +/−90° phase shift. The impact of acoustical streaming to the liquid diffusion kinetics in the microchannel and to the kinetics of adsorption of the bovine serum albumin (BSA) to the gold surface was investigated experimentally. For microfluidic experiments, CMUTs were assembled with 100 deep microchannels. It was determined that acoustical streaming can improve the diffusion rate through the microchannel. Also, it was shown that BSA adsorption rate can be controlled by changing the phase shift during excitation of the Sholte type waves. [2016–0224] Autors: Donatas Pelenis;Dovydas Barauskas;Evaldas Sapeliauskas;Gailius Vanagas;Marius Mikolajunas;Darius Virzonis; Appeared in: Journal of Microelectromechanical Systems Publication date: Oct 2017, volume: 26, issue:5, pages: 1012 - 1017 Publisher: IEEE
» Active Disturbance Rejection Adaptive Control of Hydraulic Servo Systems
 Abstract:This paper presents an active disturbance rejection adaptive control scheme via full state feedback for motion control of hydraulic servo systems subjected to both parametric uncertainties and uncertain nonlinearities. The proposed controller is derived by effectively integrating adaptive control with extended state observer via backstepping method. The adaptive law is synthesized to handle parametric uncertainties and the remaining uncertainties are estimated by the extended state observer and then compensated in a feedforward way. The unique features of the proposed controller are that not only the matched uncertainties but also unmatched uncertainties are estimated by constructing two extended state observers, and the parameter adaptation law is driven by both tracking errors and state estimation errors. Since the majority of parametric uncertainties can be reduced by the parameter adaptation, the task of the extended state observer is much alleviated. Consequently, high-gain feedback is avoided and improved tracking performance can be expected. The proposed controller theoretically achieves an asymptotic tracking performance in the presence of parametric uncertainties and constant disturbances. In addition, prescribed transient tracking performance and final tracking accuracy can also be guaranteed when existing time-variant uncertain nonlinearities. Comparative experimental results are obtained to verify the high tracking performance nature of the proposed control strategy. Autors: Jianyong Yao;Wenxiang Deng; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8023 - 8032 Publisher: IEEE
» Active Disturbance Rejection Control of Linear Induction Motor
 Abstract:This paper proposes the theoretical framework and the experimental application of the active disturbance rejection control to linear induction motors. Such a nonlinear control (ADRC) technique can be viewed as a particular kind of input–output linearization control, where the nonlinear transformation of the state is not computed by means of the model, but it is estimated online. Such an approach permits to cope with unmodeling dynamics, as well as uncertainty in the knowledge of the model parameters and exogenous disturbances. The effectiveness of the proposed ADRC control law has been verified both by numerical simulations and experimentally on a suitably developed test setup. Moreover, the results have been compared with those achievable with the model-based feedback linearization control. Autors: Francesco Alonge;Maurizio Cirrincione;Filippo D’Ippolito;Marcello Pucci;Antonino Sferlazza; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4460 - 4471 Publisher: IEEE
» Adaptive Auxiliary Particle Filter for Track-Before-Detect With Multiple Targets
 Abstract:A novel particle filter for multiple target tracking with track-before-detect measurement models is proposed. Particle filters efficiently perform target tracking under nonlinear or non-Gaussian models. However, their application to multiple target tracking suffers from the curse of dimensionality. We introduce an efficient particle filter for multiple target tracking which deals with the curse of dimensionality better than previously developed methods. The proposed algorithm is tested and compared to other multiple target tracking particle filters. Autors: Luis Úbeda-Medina;Ángel F. García-Fernández;Jesús Grajal; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2317 - 2330 Publisher: IEEE
» Adaptive Backstepping Control for a Class of Nonlinear Systems With Non-Triangular Structural Uncertainties
 Abstract:In this technical note, a robust adaptive control scheme is proposed based on backstepping techniques for a class of nonlinear systems with unknown parameters. A modeling error may also exist in every state equation or channel and it is bounded by a known function which is allowed to depend on all system states. It is shown that the proposed adaptive control scheme can ensure all signals in the closed-loop system bounded, if the strength of system modeling errors is sufficiently weak. Transient performance is also established. Thus stabilizing systems in classical strict-feedback forms with sufficiently small non-triangular structural perturbations is successfully addressed. In the case that system parameters are known, a non-adaptive robust controller is designed to globally exponentially stabilize such a class of nonlinear systems. Finally simulation studies are used to verify the effectiveness of the proposed scheme. Autors: Jianping Cai;Changyun Wen;Hongye Su;Zhitao Liu;Lantao Xing; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5220 - 5226 Publisher: IEEE
» Adaptive Computer-Aided Tuning of Coupled-Resonator Diplexers With Wire $T$ -Junction
 Abstract:This paper is devoted to theoretical and practical issues concerning computer-aided tuning (CAT) of coupled-resonator diplexers with tapped wire T-junction. Special attentions are paid to the following aspects: 1) finding an appropriate circuit model to represent the tapped wire T-junction; 2) developing a legitimate transformation strategy to obtain the coupling matrix of the right form corresponding to the topology of the diplexer containing a tapped wire T-junction; and 3) proposing an adaptive CAT scheme that takes stray couplings into account in a dynamically optimized target coupling matrix. A conventional combline diplexer and a helical resonator diplexer are used as examples to demonstrate the circuit model extraction procedure and the adaptive CAT concept, showing the effectiveness and robustness of the proposed adaptive CAT method for practical applications. Autors: Ping Zhao;Ke-Li Wu; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Oct 2017, volume: 65, issue:10, pages: 3856 - 3865 Publisher: IEEE
» Adaptive Driving Bus Voltage and Energy Recycling Control Schemes for Low-Power AC–DC RGB-LED Drivers
 Abstract:A low-power ac-dc light-emitting diode (LED) driver with adaptive driving bus voltage (ADBV) and energy recycling (ER) control schemes is proposed to drive red, green, and blue LEDs in series to achieve high efficiency. The bus voltage of the power factor correction flyback converter with the ADBV control is always adjusted, so as to reduce power loss on current regulators. However, since the small bandwidth of the flyback converter and large bus capacitor limit the transient response of the flyback converter, it is difficult to maintain the voltage across current regulators at the minimum value. The ER control is proposed to accelerate the transient response of the bus voltage, making the voltage across current regulators as close to the minimum voltage as possible. Furthermore, extra energy is stored and restored on the recycling capacitor when the bus voltage is switched between different supplying levels without consuming much power due to the ER control. The experimental waveforms of the laboratory prototype are shown to confirm the validity of the proposed schemes. Autors: Pang-Jung Liu;Kai-Lin Peng; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 7741 - 7748 Publisher: IEEE
» Adaptive Dynamic Surface Control for a Hypersonic Aircraft Using Neural Networks
 Abstract:A hypersonic aircraft dynamic model is highly nonlinear because its flight conditions are usually determined at high altitude and Mach number. Therefore, there always exist differences between the dynamical model and real system, and uncertainties during the flight, thus, leading significant degradation of control performance. To solve the performance degradation problem, this paper proposes neural networks-based adaptive velocity and altitude tracking controllers. In order for that, the hypersonic aircraft model is transformed into an uncertain feedback system, which has both matched and unmatched uncertainties, by differentiating the velocity and altitude with respect to time. Then, the overall tracking control system is designed systematically by introducing virtual control inputs and dynamic surface control. During the design process, an inverse of an input gain matrix is directly trained and adapted to remove the matched uncertainty and controller singularity problem simultaneously. In addition, several adaptive elements with saturation functions are added to handle all the matched and unmatched uncertainties. The proposed controller guarantees the uniformly ultimate boundedness of the tracking error by utilizing deadzoned errors. Finally, numerical simulations with the uncertain hypersonic aircraft are performed to demonstrate the effectiveness of the proposed approach. Autors: Jongho Shin; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2277 - 2289 Publisher: IEEE
» Adaptive Eulerian Video Processing of Thermal Video: An Experimental Analysis
 Abstract:The use of spatiotemporal video processing to extract biosignals is an emerging technique. This paper aims to build upon current work through robust experimentation and analysis. A blood flow simulation model was captured by thermal and optical cameras, while hot water was pumped through the system. Additionally, five subjects were recruited to perform two experimental trials: a facial perfusion trial and an arm blood occlusion trial, for which subjects sat quietly, while video data were captured using thermal and optical cameras. Each video was subjected to region of interest selection and adaptive Eulerian video magnification (EVM); the iterative application of EVM, first with a wide temporal bandpass filter and low amplification factor and again with a narrower, targeted temporal bandpass filter and higher amplification factor. The results from the simulation experiments indicated that thermal video in conjunction with adaptive EVM processing can reveal variations in temperature indicative of pulse rate in a controlled system of known variables. This process helped to better characterize Eulerian signal enhancement versus Eulerian noise enhancement. The results from the facial perfusion experiments suggest that the adaptive EVM processing of thermal video results in signals representative of facial perfusion rate. The results from the blood occlusion experiments revealed an occlusion temperature pattern, but not a perfusion rate. This paper therefore further demonstrated the potential of thermal video in conjunction with adaptive EVM methods to extract a signal representative of facial perfusion rate, and illustrated the need for more research on thermal video and adaptive EVM. Autors: Stephanie Bennett;Tarek Nasser El Harake;Rafik Goubran;Frank Knoefel; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Oct 2017, volume: 66, issue:10, pages: 2516 - 2524 Publisher: IEEE
» Adaptive Filtering Under a Variable Kernel Width Maximum Correntropy Criterion
 Abstract:The maximum correntropy criterion (MCC) algorithm with constant kernel width leads to a tradeoff problem in terms of convergence rate and steady-state misalignment. Thus, this brief proposes a variable kernel width (VKW) MCC algorithm to overcome this problem. The optimal kernel width of the proposed VKW-MCC algorithm is calculated at each iteration by maximizing with respect to the kernel width , wherein the kernel width is a function of the error, to make the error with greatest attenuation along the direction of the gradient ascent. Simulations in the contexts of system identification and echo cancellation have demonstrated that the proposed VKW-MCC algorithm yields a superior performance. Autors: Fuyi Huang;Jiashu Zhang;Sheng Zhang; Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs Publication date: Oct 2017, volume: 64, issue:10, pages: 1247 - 1251 Publisher: IEEE
» Adaptive Fuzzy Asymptotic Control of MIMO Systems With Unknown Input Coefficients Via a Robust Nussbaum Gain-Based Approach
 Abstract:This paper proposes an adaptive fuzzy asymptotic control method for multiple input multiple output (MIMO) nonlinear systems with unknown input coefficients, with a focus on handling unknown input nonlinearities and control directions. For all the existing Nussbaum gain-based approaches, it is difficult to investigate unknown input coefficients problem since multiple time-varying coefficients and disturbances coexist and should be simultaneously tackled in the stability analysis. To overcome the above difficulty, we propose a robust Nussbaum gain-based approach for the adaptive fuzzy asymptotic control of MIMO nonlinear systems. Benefiting from the proposed Nussbaum gain-based approach, bounded disturbances including unmodeled system dynamics and universal approximation errors are handled. Furthermore, the proposed approach helps extend the bounded fuzzy control result to the asymptotic convergence. Hence, both the control robustness and control accuracy are prompted within the frame of the developed Nussbaum gain approach. Finally, a simulation example is carried out to illustrate the effectiveness of the proposed control method. Autors: Ci Chen;Zhi Liu;Kan Xie;Yanjun Liu;Yun Zhang;C. L. Philip Chen; Appeared in: IEEE Transactions on Fuzzy Systems Publication date: Oct 2017, volume: 25, issue:5, pages: 1252 - 1263 Publisher: IEEE
» Adaptive Fuzzy Hierarchical Sliding-Mode Control for a Class of MIMO Nonlinear Time-Delay Systems With Input Saturation
 Abstract:In this paper, an adaptive fuzzy hierarchical sliding-mode control method for a class of multiinput multioutput unknown nonlinear time-delay systems with input saturation is proposed. The studied system is first transformed into an equivalent system. Subsequently, based on sliding-mode control technology and the concept of hierarchical design, a set of adaptive fuzzy hierarchical sliding-mode controllers are designed for the new defined system by using fuzzy systems to approximate uncertain functions and compensate input saturation. Choosing an appropriate Lyapunov–Krasovskii function, it is theoretically proved that all the signals in the closed-loop system together with the proposed sliding surfaces are uniformly ultimately bounded under our designed adaptive fuzzy controllers. Simulation results demonstrate the effectiveness of the proposed design techniques for the systems under consideration. Autors: Xudong Zhao;Haijiao Yang;Weiguo Xia;Xinyong Wang; Appeared in: IEEE Transactions on Fuzzy Systems Publication date: Oct 2017, volume: 25, issue:5, pages: 1062 - 1077 Publisher: IEEE
» Adaptive Group Shuffled Decoding for LDPC Codes
 Abstract:We propose new grouping methods for group shuffled (GS) decoding of both regular and irregular low-density parity check cods. These methods are applicable for the belief-propagation as well as the min-sum-based GS decoders. Integer-valued metrics for measuring the reliability of each tentative variable node (VN) decision and the associated likelihood of being corrected are developed. The metrics are used to determine the VN updating priority, so the grouping may vary in each iteration. We estimate the computation complexity needed to adaptively regroup VNs. Numerical results show that our GS algorithms improve the performance of some existing GS belief-propagation decoders. Autors: Tofar C.-Y. Chang;Yu T. Su; Appeared in: IEEE Communications Letters Publication date: Oct 2017, volume: 21, issue:10, pages: 2118 - 2121 Publisher: IEEE
» Adaptive Impedance Control of Human–Robot Cooperation Using Reinforcement Learning
 Abstract:This paper presents human-robot cooperation with adaptive behavior of the robot, which helps the human operator to perform the cooperative task and optimizes its performance. A novel adaptive impedance control is proposed for the robotic manipulator, whose end-effector's motions are constrained by human arm motion limits. In order to minimized motion tracking errors and acquire an optimal impedance mode of human arms, the linear quadratic regulation (LQR) is formulated; then, integral reinforcement learning (IRL) has been proposed to solve the given LQR with little information of the human arm model. Considering human-robot interaction force during the robot performing manipulation, a novel barrier-Lyapunov-function-based adaptive impedance control incorporating adaptive parameter learning is developed for physical limits, transient perturbations, and time-varying dynamics. Experimental results validate that the proposed controller is effective in assisting the operator to perform the human-robot cooperative task. Autors: Zhijun Li;Junqiang Liu;Zhicong Huang;Yan Peng;Huayan Pu;Liang Ding; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8013 - 8022 Publisher: IEEE
» Adaptive Inverse Control for Gripper Rotating System in Heavy-Duty Manipulators With Unknown Dead Zones
 Abstract:The gripper rotation system of a heavy-duty manipulator is generally driven by hydraulic motors, and it is difficult to guarantee the accuracy of the rotation angle using conventional control methods due to the existence of dead zones with unknown characteristics. This paper proposes an adaptive inverse dead-zone control method, in which the gradient projection technique is applied to design an adaptive updating law for estimating the inverse dead-zone parameters online. First, a dynamic model of the gripper rotation system is presented with an analysis of its dead-zone characteristics. Then, the controller is designed based on a Takagi-Sugeno fuzzy model, and the estimated values of the inverse dead-zone parameters are shown to converge to their true values. Finally, the performance of the proposed adaptive control method is experimentally demonstrated on an actual forging manipulator. Comparisons with a fixed inverse dead-zone control method demonstrate the effectiveness and applicability of the proposed control method. Autors: Hua Deng;Jiehua Luo;Xiaogang Duan;Guoliang Zhong; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 7952 - 7961 Publisher: IEEE
» Adaptive Multimedia Data Forwarding for Privacy Preservation in Vehicular Ad-Hoc Networks
 Abstract:Vehicular ad-hoc networks (VANETs) have drawn much attention of researchers. The vehicles in VANETs frequently join and leave the networks, and therefore restructure the network dynamically and automatically. Forwarded messages in vehicular ad-hoc networks are primarily multimedia data, including structured data, plain text, sound, and video, which require access control with efficient privacy preservation. Ciphertext-policy attribute-based encryption (CP-ABE) is adopted to meet the requirements. However, solutions based on traditional CP-ABE suffer from challenges of the limited computational resources on-board units equipped in the vehicles, especially for the complex policies of encryption and decryption. In this paper, we propose a CP-ABE delegation scheme, which allows road side units (RSUs) to perform most of the computation, for the purpose of improving the decryption efficiency of the vehicles. By using decision tree to jointly optimize multiple factors, such as the distance from RSU, the communication and computational cost, the CP-ABE delegation scheme is adaptively activated based on the estimation of various vehicles decryption overhead. Experimental results thoroughly demonstrate that our scheme is effective and efficient for multimedia data forwarding in vehicular ad-hoc networks with privacy preservation. Autors: Yingjie Xia;Wenzhi Chen;Xuejiao Liu;Luming Zhang;Xuelong Li;Yang Xiang; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Oct 2017, volume: 18, issue:10, pages: 2629 - 2641 Publisher: IEEE
» Adaptive Nonlocal Sparse Representation for Dual-Camera Compressive Hyperspectral Imaging
 Abstract:Leveraging the compressive sensing (CS) theory, coded aperture snapshot spectral imaging (CASSI) provides an efficient solution to recover 3D hyperspectral data from a 2D measurement. The dual-camera design of CASSI, by adding an uncoded panchromatic measurement, enhances the reconstruction fidelity while maintaining the snapshot advantage. In this paper, we propose an adaptive nonlocal sparse representation (ANSR) model to boost the performance of dual-camera compressive hyperspectral imaging (DCCHI). Specifically, the CS reconstruction problem is formulated as a 3D cube based sparse representation to make full use of the nonlocal similarity in both the spatial and spectral domains. Our key observation is that, the panchromatic image, besides playing the role of direct measurement, can be further exploited to help the nonlocal similarity estimation. Therefore, we design a joint similarity metric by adaptively combining the internal similarity within the reconstructed hyperspectral image and the external similarity within the panchromatic image. In this way, the fidelity of CS reconstruction is greatly enhanced. Both simulation and hardware experimental results show significant improvement of the proposed method over the state-of-the-art. Autors: Lizhi Wang;Zhiwei Xiong;Guangming Shi;Feng Wu;Wenjun Zeng; Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence Publication date: Oct 2017, volume: 39, issue:10, pages: 2104 - 2111 Publisher: IEEE
» Adaptive OFDM Integrated Radar and Communications Waveform Design Based on Information Theory
 Abstract:To improve the effectiveness of limited spectral resources, an adaptive orthogonal frequency division multiplexing integrated radar and communications waveform design method is proposed. First, the conditional mutual information (MI) between the random target impulse response and the received signal, and the data information rate (DIR) of frequency selective fading channel are formulated. Then, with the constraint on the total power, the optimization problem, which simultaneously considers the conditional MI for radar and DIR for communications, is devised, and the analytic solution is derived. With low transmit power, the designed integrated waveform outperforms the fixed waveform (i.e., equal power allocation). Finally, several simulated experiments are provided to verify the effectiveness of the designed waveform. Autors: Yongjun Liu;Guisheng Liao;Jingwei Xu;Zhiwei Yang;Yuhong Zhang; Appeared in: IEEE Communications Letters Publication date: Oct 2017, volume: 21, issue:10, pages: 2174 - 2177 Publisher: IEEE
» Adaptive Out-of-Band Interference Suppression for Coexistent Wi-Fi and Bluetooth Systems
 Abstract:Coexistence of Wi-Fi and Bluetooth (BT) systems is often necessary in various handheld devices. Due to nonlinearities of radio frequency front-end components, leakage signals from one transmitter to the other transmitter would produce out-of-band (OOB) interference and corrupt adjacent frequency bands outside the spectral masks defined in standards. In this letter, we propose an adaptive OOB interference suppression scheme based on a modified normalized least mean-squared algorithm for coexistent Wi-Fi and BT transceivers. Computer simulation results show that the proposed approach provides pretty good performance in transmitter leakage cancellation and effectively relieves the OOB interference issue. Autors: Chin-Liang Wang;Min-Chau Jan;Yuan-Shuo Chang;Erlang Wang;Ying-Hsi Lin; Appeared in: IEEE Communications Letters Publication date: Oct 2017, volume: 21, issue:10, pages: 2306 - 2309 Publisher: IEEE
» Adaptive Particle Swarm Optimization with Heterogeneous Multicore Parallelism and GPU Acceleration
 Abstract:Much progress has recently been made in global optimization, with particular attention devoted to robust nature-inspired stochastic methods for difficult, high-dimensional problems. This paper presents a computational study of an adaptation of one such method, particle swarm optimization (PSO), which is analyzed for parallelization on readily-available heterogeneous parallel computational hardware: specifically, multicore technologies accelerated by graphics processing units (GPUs), as well as Intel Xeon Phi co-processors accelerated with vectorization. In this heterogeneous approach, computationally-intensive, task-parallel components are performed with multicore parallelism and data-parallel elements are executed via co-processing (GPUs or vectorization). A computationally intensive adaptive PSO technique is parallelized according to this schema. In experiments with two high-dimensional and complex functions, large speedups can be obtained. Thus, a heterogeneous approach mitigates the time complexity of PSO adaptations, suggesting that other time-intensive stochastic methods can also benefit from the techniques proposed here. Autors: Mark P. Wachowiak;Mitchell C. Timson;David J. DuVal; Appeared in: IEEE Transactions on Parallel and Distributed Systems Publication date: Oct 2017, volume: 28, issue:10, pages: 2784 - 2793 Publisher: IEEE
 Abstract:Weather radar commonly uses a matched filter (MF) method to improve the range resolution and signal-to-noise ratio. A X-band phased array weather radar (PAWR), which is capable of 3-D precipitation observations in less than 30 s, is in operation at the Osaka University. The PAWR uses the MF method. In weather radar systems, the magnitude of the range sidelobes is an important topic because it can cause overestimation of the received power from a target, such as precipitation or ground clutter echoes. We propose a minimum mean square error (MMSE)-based pulse compression method to reduce the range sidelobes of the PAWR. We evaluated an MF, an MF with a raised-cosine window, and MMSE methods using numerical simulations and actual measurement data obtained from the PAWR. The results show that the MMSE method is clearly superior to the MF and MF with a raised-cosine filter methods when considering the reduction in the range sidelobes. Autors: H. Kikuchi;E. Yoshikawa;T. Ushio;F. Mizutani;M. Wada; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Oct 2017, volume: 14, issue:10, pages: 1810 - 1814 Publisher: IEEE
» Adaptive Search Range for HEVC Motion Estimation Based on Depth Information
 Abstract:High Efficiency Video Coding achieves twofold coding efficiency improvement compared with its predecessor H.264/MPEG-4 Advanced Video Coding. However, it suffers from high computational complexity due to its quad-tree structure in motion estimation (ME). This paper exposes the use of depth maps in the multiview video plus depth format for relieving the computational burden. The depth map provides an intimation of the objects’ distance from the projected screen in a 3D scene, which is explored in adaptive search range determination in this paper. The proposed algorithm exploits the high temporal correlation between the depth map and the motion in texture. By utilizing this correlation, a depth/motion relationship map is built for a mapping process. For each block, this forms a tailor-made search range with a motion-aware asymmetric shape to skip unnecessary search points in ME. The obtained search range can be further adjusted by taking the influence of 3D-to-2D projection into consideration. Simulation results reveal that, compared to the full search approach, the proposed algorithm can reduce the complexity by 93% on average, whereas the coding efficiency can be maintained. Besides, the proposed search range determination can work well with other fast search ME algorithms in the literature. Autors: Tsz-Kwan Lee;Yui-Lam Chan;Wan-Chi Siu; Appeared in: IEEE Transactions on Circuits and Systems for Video Technology Publication date: Oct 2017, volume: 27, issue:10, pages: 2216 - 2230 Publisher: IEEE
 Abstract:In this letter, an adaptive spatial modulation (SM) scheme, in which the spatial signatures of the transmitted signals are adaptively selected according to the channel responses, is proposed for the uplink of a millimeter-wave communication system. We first use an iterative method to search for the spatial signatures that maximize the minimum Euclidean distance of the SM symbols. Following this, a suboptimal scheme is provided to reduce the computational complexity. Numerical results show that the proposed adaptive SM scheme can effectively reduce the system symbol-error rate. Autors: Sheng Luo;Xuan Tuong Tran;Kah Chan Teh;Kwok Hung Li; Appeared in: IEEE Communications Letters Publication date: Oct 2017, volume: 21, issue:10, pages: 2178 - 2181 Publisher: IEEE
» Adaptive Video Streaming With Network Coding Enabled Named Data Networking
 Abstract:The fast and huge increase of Internet traffic motivates the development of new communication methods that can deal with the growing volume of data traffic. To this aim, named data networking (NDN) has been proposed as a future Internet architecture that enables ubiquitous in-network caching and naturally supports multipath data delivery. Particular attention has been given to using dynamic adaptive streaming over HTTP to enable video streaming in NDN as in both schemes data transmission is triggered and controlled by the clients. However, state-of-the-art works do not consider the multipath capabilities of NDN and the potential improvements that multipath communication brings, such as increased throughput and reliability, which are fundamental for video streaming systems. In this paper, we present a novel architecture for dynamic adaptive streaming over network coding enabled NDN. In comparison to previous works proposing dynamic adaptive streaming over NDN, our architecture exploits network coding to efficiently use the multiple paths connecting the clients to the sources. Moreover, our architecture enables efficient multisource video streaming and improves resiliency to Data packet losses. The experimental evaluation shows that our architecture leads to reduced data traffic load on the sources, increased cache-hit rate at the in-network caches and faster adaptation of the requested video quality by the clients. The performance gains are verified through simulations in a Netflix-like scenario. Autors: Jonnahtan Saltarin;Eirina Bourtsoulatze;Nikolaos Thomos;Torsten Braun; Appeared in: IEEE Transactions on Multimedia Publication date: Oct 2017, volume: 19, issue:10, pages: 2182 - 2196 Publisher: IEEE
» Adjustable Microwave Magnetic Spectra of Metamaterials Based on Ferromagnetic Film Laminates
 Abstract:A resonant RLC circuit with a magnetic core has been investigated experimentally and theoretically as a promising metamaterial cell design. Laminates of multilayer ferromagnetic films serve as a magnetic core. The ferromagnetic resonance frequency of the bare laminate core is above 1 GHz. An intensive magnetic absorption peak is obtainable at lower frequencies due to a resonant wire coiled around the core. Such magnetic metamaterials seem promising for applications that require high magnetic loss at frequencies of hundreds of megahertz. This paper focuses on efficient approaches to adjusting the location of magnetic loss peak in magnetic metamaterials. High-frequency permeability of the metamaterial samples has been measured in a rectangular waveguide. It is shown that by varying the geometry, structure, and composition of the measured metamaterial samples, the magnetic spectra can be radically changed. Excitation of electromagnetic resonance in the ferromagnetic core with the resonant wire is discussed within the frame of the quasi-static approximation. Autors: S. Y. Bobrovskii;I. T. Iakubov;A. N. Lagarkov;A. V. Osipov;K. N. Rozanov; Appeared in: IEEE Transactions on Magnetics Publication date: Oct 2017, volume: 53, issue:10, pages: 1 - 6 Publisher: IEEE
» ADMM Projective Dynamics: Fast Simulation of Hyperelastic Models with Dynamic Constraints
 Abstract:We apply the alternating direction method of multipliers (ADMM) optimization algorithm to implicit time integration of elastic bodies, and show that the resulting method closely relates to the recently proposed projective dynamics algorithm. However, as ADMM is a general purpose optimization algorithm applicable to a broad range of objective functions, it permits the use of nonlinear constitutive models and hard constraints while retaining the speed, parallelizability, and robustness of projective dynamics. We further extend the algorithm to improve the handling of dynamically changing constraints such as sliding and contact, while maintaining the benefits of a constant, prefactored system matrix. We demonstrate the benefits of our algorithm on several examples that include cloth, collisions, and volumetric deformable bodies with nonlinear elasticity and skin sliding effects. Autors: Matthew Overby;George E. Brown;Jie Li;Rahul Narain; Appeared in: IEEE Transactions on Visualization and Computer Graphics Publication date: Oct 2017, volume: 23, issue:10, pages: 2222 - 2234 Publisher: IEEE
» Advanced Fast 3-D Electromagnetic Solver for Microwave Tomography Imaging
 Abstract:This paper describes a fast-forward electromagnetic solver (FFS) for the image reconstruction algorithm of our microwave tomography system. Our apparatus is a preclinical prototype of a biomedical imaging system, designed for the purpose of early breast cancer detection. It operates in the 3–6-GHz frequency band using a circular array of probe antennas immersed in a matching liquid; it produces image reconstructions of the permittivity and conductivity profiles of the breast under examination. Our reconstruction algorithm solves the electromagnetic (EM) inverse problem and takes into account the real EM properties of the probe antenna array as well as the influence of the patient’s body and that of the upper metal screen sheet. This FFS algorithm is much faster than conventional EM simulation solvers. In comparison, in the same PC, the CST solver takes ~45 min, while the FFS takes ~1 s of effective simulation time for the same EM model of a numerical breast phantom. Autors: Nikolai Simonov;Bo-Ra Kim;Kwang-Jae Lee;Soon-Ik Jeon;Seong-Ho Son; Appeared in: IEEE Transactions on Medical Imaging Publication date: Oct 2017, volume: 36, issue:10, pages: 2160 - 2170 Publisher: IEEE
» Advanced Synchronizing Systems for Offshore Power Systems: Improving System Reliability and Flexibility
 Abstract:Small power systems, such as those found on offshore platforms, are fragile, yet they must operate reliably for economy and the safety of both personnel and the environment. These systems often include combustion turbine generators for the main process power requirements and black start diesel generators that can supply essential and emergency buses; the diesel generators can also be used to restart the main generation systems in the event of a power-system collapse. The power distribution systems on these offshore platforms have built-in redundancy with multiple circuits to supply critical loads for fault tolerance and operating flexibility. A system to easily and safely synchronize islanded buses via many possible synchronization points can revolutionize the operational flexibility and, therefore, the safety and reliability of the power system. This article reports on advanced synchronizing systems installed on two offshore platforms. Autors: Michael J. Thompson;Allen Li;Roy Luo;Michael C. Tu;Iris Urdaneta; Appeared in: IEEE Industry Applications Magazine Publication date: Oct 2017, volume: 23, issue:5, pages: 60 - 69 Publisher: IEEE
» Advances in Magnetics Epitaxial Multiferroic Heterostructures and Applications
 Abstract:The ever increasing demand for ultralow power electronics has propelled the exploration of novel multiferroics for realizing voltage control of magnetism in an energy efficient manner. Epitaxial multiferroic heterostructures, possessing a strong lattice-coupled mechanical interface and allowing an electric field (E-field) significantly modulating spin, charge, lattice, and orbital order parameters, have drawn much attention for creating novel magnetoelectric (ME) coupling effects. In this paper, we review the recent progress on control of ME properties in epitaxial multiferroic heterostructures, including their novel physical properties, various strong interfacial ME interactions, and potential applications. Meanwhile, the essential interfacial couplings, allowing cross-tuning of lattice and charge-coupled parameters, have been extensively reviewed. Electric tuning of magnetism in epitaxial multiferroic heterostructures provides a great platform to develop lightweight, compact, and energy-efficient spintronic or electronic devices. Autors: Mingmin Zhu;Tianxiang Nan;Bin Peng;Yijun Zhang;Ziyao Zhou;Xi Yang;Wei Ren;Nian X. Sun;Ming Liu; Appeared in: IEEE Transactions on Magnetics Publication date: Oct 2017, volume: 53, issue:10, pages: 1 - 16 Publisher: IEEE
» Aggregating LTE and Wi-Fi: Toward Intra-Cell Fairness and High TCP Performance
 Abstract:The data explosion and resource scarcity of mobile cellular networks require new paradigms to effectively integrate heterogeneous radio resources. Of many candidate approaches, smart aggregation of LTE and Wi-Fi radios is a promising solution that bonds heterogeneous links to meet a mobile terminal’s bandwidth need. Motivated by the existence of a significant number of carrier operated Wi-Fi APs, we propose an easily deployable mechanism, called LTE-W, which efficiently utilizes LTE and Wi-Fi links only with the minimum change of eNodeBs, LTE backhaul networks, and mobile terminals. LTE-W, which is a link-level aggregation mechanism, has the following two key components: 1) mode selection and 2) bearer-split scheduling. First, in the mode selection, LTE-W internally decides who should be served by either LTE-only or LTE-Wi-Fi aggregation considering intra-cell fairness rather than just following users’ intention of aggregation. For the users’ preference to be offered the aggregation service, we choose a bearer (roughly defined in LTE as a set of flows with a similar QoS) as a basic unit of aggregation and propose a smart intra-bearer scheduling algorithm that splits a bearer’s traffic into LTE and Wi-Fi links, considering the performance of TCP flows that take two heterogeneous wireless links. We evaluate our mechanism using the NS-3 with LENA, under various configurations, including nodes with mobility and HTTP traffic, and compare it with a transport-level aggregation mechanism, multipath TCP (MPTCP), demonstrating that LTE-W significantly improves MPTCP, e.g., up to 75% in terms of Jain’s fairness index. Autors: Boram Jin;Segi Kim;Donggyu Yun;Hojin Lee;Wooseong Kim;Yung Yi; Appeared in: IEEE Transactions on Wireless Communications Publication date: Oct 2017, volume: 16, issue:10, pages: 6295 - 6308 Publisher: IEEE
» Albedo Retrieval From Multispectral Landsat 8 Observation in Urban Environment: Algorithm Validation by in situ Measurements
 Abstract:The surface albedo in urban environment represents one of the most influencing parameters in the formation of the Urban Heat Island (UHI). Its assessment is therefore strategic to undertake actions for the UHI mitigation: the increase of urban surface reflectivity is an example of cooling strategies increasingly proposed and developed. Spaceborne observations could give a significant contribution supplying albedo maps, and different retrieval algorithms estimating broadband albedo from narrow band reflectivities provided by satellite sensors were proposed and validated in literature. In this study, the accuracy of two well-known retrieval algorithms applied to Landsat 8 OLI reflectivities was assessed in a city of Central Italy (Perugia), selecting test sites having different land cover types. Since the root mean square error of the estimated albedo was quite high (0.07–0.08), a custom retrieval algorithm was developed to evaluate the potential improvement in the narrowband reflectivity-broadband albedo conversion for the case study. This analysis was made possible thanks to an in situ measurement campaign, carried out during the summer months of 2016. The selected sites, having quite homogenous features inside the urban environment, also demonstrated that the albedo values are not significantly affected by the hour of the day, if measurements are taken near noon (variation less than 7%). Spaceborne observations showed once again a powerful tool for monitoring large areas with a quite good spatial resolution (30 m), even if an improvement of the literature albedo retrieval algorithms is required and possible in an urban context. Autors: Giorgio Baldinelli;Stefania Bonafoni;Antonella Rotili; Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Publication date: Oct 2017, volume: 10, issue:10, pages: 4504 - 4511 Publisher: IEEE
» Algorithms for Accurate Spectral Analysis in the Presence of Arbitrary Noncoherency and Large Distortion
 Abstract:In spectral analysis, achieving coherent sampling, especially when signals have large distortion, has been a challenge for many years. This paper introduces three algorithms to resolve this issue. In comparison to previous algorithms, and two widely used methods in industry: windowing and four-parameter sine wave fit, these new algorithms are capable of obtaining accurate spectral results of the signal, while achieving high accuracy as well as computational efficiency. The novel contribution of this paper is that not only does it propose two new algorithms, but also it analyzes their advantages and limitations in detail, providing their trade-offs and different fields of applications. Extensive simulations and measurements are performed to validate these algorithms. Combined with their high accuracy, computational efficiency, and robustness against signal purity, these algorithms are readily available to be implemented for bench or on-chip testing. In addition, it is suitable for data converter spectral testing when noncoherent sampling is present, and spectrally pure test signal source is not available. Autors: Yuming Zhuang;Degang Chen; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Oct 2017, volume: 66, issue:10, pages: 2556 - 2565 Publisher: IEEE
» Aligned Reverse Frame Structure for Interference Mitigation in Dynamic TDD Systems
 Abstract:The dynamic time division duplex (TDD) system has been proposed as a way to meet today’s asymmetrically and dynamically changing traffic demand. However, this approach causes cross-link interference, because neighboring base stations and user elements transmit in opposite directions. In this paper, we investigate and analyze the characteristics of cross-link interference in dynamic TDD systems. Based on this observation, we propose an aligned reverse frame structure to utilize and cancel the cross-link interference. Mathematical analysis and numerical results verify that the proposed scheme achieves performance enhancement in terms of capacity compared with conventional dynamic TDD systems. Autors: Kwonjong Lee;Yosub Park;Minsoo Na;Hanho Wang;Daesik Hong; Appeared in: IEEE Transactions on Wireless Communications Publication date: Oct 2017, volume: 16, issue:10, pages: 6967 - 6978 Publisher: IEEE
» All-Fiber-Optics-Based Microwave Photonic Filter With Tunable Center Frequency and Passband Plus Notch
 Abstract:We propose and demonstrate a microwave photonic band-pass filter (MPF), which features a single light source, with continuously and independently tunable center frequency and bandwidth. The center frequency and bandwidth can be adjusted by tuning the variable optical delay line and the position of a spatial filter, respectively. Using a balanced photodetector, the baseband, which is ineradicable in some conventional designs, and the common-mode noise are canceled in our proof-of-concept experiment. Alternatively, a notch with continuously tunable frequency can also be added in the MPF. The experimental measurements of the frequency response of this MPF are demonstrated, which have a good agreement with the theoretical simulations. Autors: Xiao Zhang;Chengming Wang;Wenchao Liao;Wenxin Zhang;Shengnan Ai;Zhangkai Peng;Ping Xue; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 8 Publisher: IEEE
» All-Optical Actively Mode-Locked Fiber Laser at 2-μm Based on Interband Modulation
 Abstract:In this paper, we have achieved a high repetition rate and tunable pulse generation near ∼2 μm through an all-optical actively mode-locked fiber laser. The performances of the fiber laser have been systematically investigated through numerical simulations. The thulium-doped fiber laser cavity is modulated by the optical injection at 1.55 μm via a nonlinear optical loop mirror in which a specially-designed group-velocity-matching highly nonlinear fiber is incorporated. According to the simulation results, up to 40-GHz pulse train with picosecond tunable pulse width and peak power can be produced. Moreover, the repetition rate can be further enlarged with the help of higher gain. The impacts of gain coefficient, cavity length, and repetition rate on the output are studied in details. The proposed mode-locked fiber laser can be potentially used for future 2- μm fiber communication. Autors: Xu Wu;Zhichao Wu;Tianye Huang;Bingwei Chen;Kaixuan Ren;Songnian Fu; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 8 Publisher: IEEE
» All-Optical Intensity Modulator by Polarization-Dependent Graphene-Microfiber Waveguide
 Abstract:We demonstrated all-optical intensity modulator based on polarization-dependent graphene-covered microfiber (GMF) waveguide. By controlling the polarization mode of incident light, a greatly adjustable enhanced interaction between the propagating light and the graphene can be obtained via the evanescent field of the microfiber. By employing 980-nm pump light and 1550-nm signal light in continuous wave, the strong light–graphene interaction enables a maximum modulation depth of ∼20.86 dB, and by pumping 980 nm wave pulses, we obtained the temporal response characteristics of signal light with modulation rate of 5.13 kHz. This all-optical intensity modulator is compatible with optical fiber systems, and features with ease of fabrication, and steerable high modulation depth, which show potential in graphene's applications such as all-optical switching and all-optical communications. Autors: Ruiduo Wang;Diao Li;Hao Wu;Man Jiang;Zhipei Sun;Yonghui Tian;Jintao Bai;Zhaoyu Ren; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 8 Publisher: IEEE
» An Accurate and Fast Converging Short-Term Load Forecasting Model for Industrial Applications in a Smart Grid
 Abstract:Short-term load forecasting (STLF) models are very important for electric industry in the trade of energy. These models have many applications in the day-to-day operations of electric utilities such as energy generation planning, load switching, energy purchasing, infrastructure maintenance, and contract evaluation. A large variety of STLF models have been developed that trade off between forecast accuracy and convergence rate. This paper presents an accurate and fast converging STLF model for industrial applications in a smart grid. In order to improve the forecast accuracy, modifications are devised in two popular techniques: mutual information based feature selection; and enhanced differential evolution algorithm based error minimization. On the other hand, the convergence rate of the overall forecast strategy is enhanced by devising modifications in the heuristic algorithm and in the training process of the artificial neural network. Simulation results show that accuracy of the newly proposed forecast model is 99.5% with moderate execution time, i.e., we have decreased the average execution of the existing bilevel forecast strategy by 52.38%. Autors: Ashfaq Ahmad;Nadeem Javaid;Mohsen Guizani;Nabil Alrajeh;Zahoor Ali Khan; Appeared in: IEEE Transactions on Industrial Informatics Publication date: Oct 2017, volume: 13, issue:5, pages: 2587 - 2596 Publisher: IEEE
» An Accurate Method for MPPT to Detect the Partial Shading Occurrence in a PV System
» An Accurate Representation of Incoherent Layers Within One-Dimensional Thin-Film Multilayer Structures With Equivalent Propagation Matrices
 Abstract:We propose a novel approach of including incoherent layers into an arbitrary multilayer stack and treating them using the conventional matrix methods in the wave-optics regime. The proposed “Equivalent Matrix Method” (EMM) calculates two phase-shift additions that totally cancel out the interference terms in front of, and behind the incoherent layer. The additions are merged into an equivalent incoherent layer propagation matrix that can be used in the standard coherent calculation. The mathematical model that we describe in the paper has three important advantages. First, the exact calculation of the phase-shift additions efficiently replaces various phase-averaging approaches normally used to deal with incoherency. Second, instead of an incoherent layer, we can use an equivalent coherent layer in a rigorous simulation using the phase-matching. Last, there is no energy imbalance error caused by wave coupling in lossy incoherent layers. We verify the proposed EMM against the general transfer-matrix method (GTMM) and the combined ray optics/wave optics model (CROWM) using two cases: an arbitrary multilayer structure with four incoherent glass layers, and a thin-film hydrogenated amorphous silicon solar cell. In both cases, the EMM yielded the same results as the GTMM and CROWM, thus confirming its regularity. Autors: J. Puhan;B. Lipovšek;Á. Bűrmen;I. Fajfar; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 12 Publisher: IEEE
» An Achievable Rate Region Based on Coset Codes for Multiple Access Channel With States
 Abstract:We prove that the ensemble of the nested coset codes built on finite fields achieves the capacity of arbitrary discrete memoryless point-to-point channels. Exploiting its algebraic structure, we develop a coding technique for communication over general discrete multiple access channel with channel state information distributed noncausally at the transmitters. We build an algebraic coding framework for this problem using the ensemble of Abelian group codes and, thereby, derive a new achievable rate region. We identify non-additive and non-symmetric examples for which the proposed achievable rate region is strictly larger than the one achievable using random unstructured codes. Autors: Arun Padakandla;S. Sandeep Pradhan; Appeared in: IEEE Transactions on Information Theory Publication date: Oct 2017, volume: 63, issue:10, pages: 6393 - 6415 Publisher: IEEE
» An Adaptive Fixed-Point Iteration Algorithm for Finite-Element Analysis With Magnetic Hysteresis Materials
 Abstract:In this paper, an adaptive fixed-point iteration algorithm for 2-D/3-D finite-element analysis with hysteresis is proposed. The iteration starts with the -correction scheme. If the solution is not converged to a given accuracy after a certain number of iterations, the iteration will be continued by switching to the -correction scheme. Based on the combined use of the two correction schemes during the whole iteration process, the solution with the minimum error together with the scheme type is recorded and will be used as the final solution at the current time step. At the same time, the recorded scheme type will be used as the initial scheme type for the next time step. The numerical validation shows that the proposed algorithm not only has very fast convergence rate, but is also very stable. Autors: P. Zhou;D. Lin;C. Lu;M. Rosu;D. M. Ionel; Appeared in: IEEE Transactions on Magnetics Publication date: Oct 2017, volume: 53, issue:10, pages: 1 - 5 Publisher: IEEE
» An Adaptive PAM-4 Analog Equalizer With Boosting-State Detection in the Time Domain
 Abstract:This paper introduces an improved adaptive analog equalizer that is required in high speed serial receivers using four-level pulse amplitude modulation signaling. By performing boosting-state detection in the time domain, the proposed adaptive analog equalizer can effectively overcome a serious problem that the received signal’s eye-opening tends to be compromised by the convergence accuracy of the adaptive control loop. To suppress the pattern-dependent jitters (PDJs), an inductor-less, cross-stage feedback structure is employed in the proposed analog equalizer to help broaden its effective tuning bandwidth. Multichannel simulations have confirmed that the proposed equalizer is able to achieve a 42% improvement in eye-height opening when compared with the equalizers employing popular spectrum-comparing schemes. Trellis diagram analyses under different date rates have revealed that the bandwidth of the proposed equalizer can be extended by as much as 60%, thus effectively bringing the PDJs from 44% down to 27.5%. Autors: Shunbin Li;Yingtao Jiang;Peng Liu; Appeared in: IEEE Transactions on Very Large Scale Integration Systems Publication date: Oct 2017, volume: 25, issue:10, pages: 2907 - 2916 Publisher: IEEE
» An Adaptive Strips Method for Extraction Buildings From Light Detection and Ranging Data
 Abstract:A method is proposed for extracting building points set from light detecting and ranging (LiDAR) data. This proposed method is based on a strip strategy to filter building points and extract the edge point set rapidly and effectively in large-scale urban building groups. This approach divides the LiDAR data into small strips and classifies each strip of data with an adaptive-weight polynomial in the - or -direction. The building edge set can then be extracted by utilizing the regional clustering relationships between points. The results of a series of experiments show that our method can not only filter the LiDAR point cloud, which performs better than existing methods, but also determine the building edge set efficiently, with an average accuracy rate of up to 91.1%. Autors: Xionggao Zou;Yueping Feng;Huiying Li;Jinlong Zhu; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Oct 2017, volume: 14, issue:10, pages: 1651 - 1655 Publisher: IEEE
» An Algorithm for Motif-Based Network Design
 Abstract:A determinant property of the structure of a biological network is the distribution of local connectivity patterns, i.e., network motifs. In this work, a method for creating directed, unweighted networks while promoting a certain combination of motifs is presented. This motif-based network algorithm starts with an empty graph and randomly connects the nodes by advancing or discouraging the formation of chosen motifs. The in- or out-degree distribution of the generated networks can be explicitly chosen. The algorithm is shown to perform well in producing networks with high occurrences of the targeted motifs, both ones consisting of three nodes as well as ones consisting of four nodes. Moreover, the algorithm can also be tuned to bring about global network characteristics found in many natural networks, such as small-worldness and modularity. Autors: Tuomo Mäki-Marttunen; Appeared in: IEEE/ACM Transactions on Computational Biology and Bioinformatics Publication date: Oct 2017, volume: 14, issue:5, pages: 1181 - 1186 Publisher: IEEE
» An Analog Front-End Chip With Self-Calibrated Input Impedance for Monitoring of Biosignals via Dry Electrode-Skin Interfaces
 Abstract:This paper demonstrates an input impedance boosting method that was developed for long-term monitoring of electroencephalography signals. An instrumentation amplifier was designed with a negative capacitance generation feedback (NCGFB) technique to cancel the adverse effects of input capacitances from electrode cables and printed circuit boards. The NCGFB boosts the measured impedance from below 40 M to above 500 M at 50 Hz when the equivalent capacitance at the inputs is up to 150 pF. The prototype chip includes an automatic calibration system to adaptively enhance the input impedance through on-chip test signal generation, measurement, and the automatic digital control of the NCGFB. Consisting of an instrumentation amplifier, a low-pass notch filter, and a variable gain amplifier in 130-nm CMOS technology, the signal path has a combined gain range of 66–93 dB with a total power consumption of 42 W. The front-end bandwidth covers 0.5–48 Hz, and its integrated input-referred noise over the bandwidth is 3.75 Vrms. The measured third-order harmonic distortion component is at least 57 dB below the fundamental signal level. A common-mode rejection ratio of 77.6 dB and a power supply rejection ratio of 74 dB were measured at 10 Hz. When activated, the auxiliary test signal generation and calibration circuits consume a power of 542 W. Autors: Chun-Hsiang Chang;Seyed Alireza Zahrai;Kainan Wang;Li Xu;Ibrahim Farah;Marvin Onabajo; Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers Publication date: Oct 2017, volume: 64, issue:10, pages: 2666 - 2678 Publisher: IEEE

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