Electrical and Electronics Engineering publications abstract of: 09-2017 sorted by title, page: 13

» Negative Reactance Impacts on the Eigenvalues of the Jacobian Matrix in Power Flow and Type-1 Low-Voltage Power-Flow Solutions
Abstract:
It was usually considered in power systems that power flow equations had multiple solutions and all the eigenvalues of Jacobian matrix at the high-voltage operable solution should have negative real parts. Accordingly, type-1 low-voltage power flow solutions are defined in the case that the Jacobian matrix has only one positive real-part eigenvalue. However, an important issue that has not been well addressed yet is that the “negative reactance” may appear in the practical power system models. Thus, the negative real-part eigenvalues of the Jacobian matrix at the high-voltage operable solution may be positive and also the type-1 low-voltage solutions could have more than one positive real-part eigenvalues, being a major challenge. Therefore, in this paper, the recognition of the type-1 low-voltage power flow solutions is re-examined with the presence of negative reactance. Selected IEEE standard power system models and the real-world Polish power systems are then tested to verify the analysis. The results reveal that the negative reactance in the practical power systems has a significant impact on the negative real-part eigenvalues of the Jacobian matrix at the high-voltage operable solution as well as the number of positive real-part eigenvalues at the type-1 low-voltage power flow solutions.
Autors: Tao Ding;Cheng Li;Yongheng Yang;Rui Bo;Frede Blaabjerg;
Appeared in: IEEE Transactions on Power Systems
Publication date: Sep 2017, volume: 32, issue:5, pages: 3471 - 3481
Publisher: IEEE
 
» Network-Preserving Sensitivity-Based Generation Rescheduling for Suppressing Power System Oscillations
Abstract:
As power system operation conditions vary, the system may move into critical operating conditions with oscillatory behaviors. In this paper, a generation rescheduling method is proposed for damping critical modes so that oscillations can be suppressed. This proposed method calculates the analytical eigenvalue sensitivity to identify the most effective generators for rescheduling to enhance the damping of the critical mode, thereby suppressing the oscillations. The eigenvalue sensitivity calculation is based on the structure-preserving network representation and the generalized eigenvalue problem. Numerical evaluation of the proposed method is performed with a focus on mode shape and participation factor analysis. The results show that the proposed method is effective in controlling power system oscillations via generation rescheduling.
Autors: Chongtao Li;Hsiao-Dong Chiang;Zhengchun Du;
Appeared in: IEEE Transactions on Power Systems
Publication date: Sep 2017, volume: 32, issue:5, pages: 3824 - 3832
Publisher: IEEE
 
» Neural Probes with Integrated Temperature Sensors for Monitoring Retina and Brain Implantation and Stimulation
Abstract:
Gold (Au) resistive temperature sensors were integrated on flexible polyimide-based neural probes to monitor temperature changes during neural probe implantation and stimulation. Temperature changes were measured as neural probes were implanted to infer the positions of the neural probes, and as the retina or the deep brain region was stimulated electrically. The temperature sensor consisted of a serpentine Au resistor and surrounded by four Au electrodes with 200 and diameter (dia.). The Au temperature sensors had temperature coefficient of 0.32%, and they were biocompatible and small in size. In vivo measurements of temperature changes during implantation and stimulation were carried out in the retina and deep brain region in rats. The desired implantation position was reached when temperature measured by the sensor increased to the calibrated level and became stable. There was no temperature increase when low level stimulation current of 8 and each for the two 200- and 400--dia. electrodes, respectively, were applied. When higher level stimulation current of 100 and each were applied to the two 200- and 400- -dia. electrodes, respectively, maximum temperature increases of 1.2 °C in retina and 1 °C in deep brain region were found.
Autors: Jiaqi Wang;Hui Xie;Tsing Chung;Leanne Lai Hang Chan;Stella W. Pang;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Sep 2017, volume: 25, issue:9, pages: 1663 - 1673
Publisher: IEEE
 
» Neuroadaptive Power Tracking Control of Wind Farms Under Uncertain Power Demands
Abstract:
Wind farm contains a large number of wind turbines, each of which is required to deliver certain amount of power so that the combined power from the wind farm is able to meet the total power demand. For such typical power tracking control problem, it is quite challenging to develop a computationally inexpensive and structurally simple solution. The problem is further complicated if the demanded power is unknown a priori and there exist modeling uncertainties as well as external disturbances in the system. In this paper, a neuroadaptive feedback control is presented. The barrier Lyapunov function based design technique is utilized to guarantee that the neural network (NN) training inputs are confined within a compact set such that the NN unit can maintain its learning/approximating functionality during the entire process of system operation. To address the issue of unknown power trajectory, an analytical model is proposed to reconstruct the unknown desired power profile. Both theoretical analysis and numerical simulation validate the effectiveness of the proposed method.
Autors: Yongduan Song;Liyuan Liang;Mi Tan;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Sep 2017, volume: 64, issue:9, pages: 7071 - 7078
Publisher: IEEE
 
» New Associate Editor
Abstract:
It is with pleasure that I welcome Prof. Piero Malcovati to the editorial board of the IEEE Journal of Solid-State Circuits as a new Associate Editor. Prof. Malcovati brings a wide expertise on sensor interface circuits, data converters, and power management systems to the Journal.
Autors: Jan Craninckx;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Sep 2017, volume: 52, issue:9, pages: 2223 - 2223
Publisher: IEEE
 
» New Control of Wind Turbines Ensuring Stable and Secure Operation Following Islanding of Wind Farms
Abstract:
This paper first presents the phenomena of the offshore wind farm (OWF) experience following the blocking of the high voltage direct current converter used for connecting the wind farm (WF) to the main onshore grid. Measurements in real large WFs show that the voltage will rise by approximately 30% within 50–100 ms in the ensuing island operation. The process is superimposed by transients caused by short but repetitive periods of saturation of the transformers. Based on the analysis of common wind turbine (WT) control concepts, it has been found that the reason for the voltage rise is the integral characteristic of the classical current controller. Generally, it seems that the current injection control, as it is used in almost all WT controls, is not suitable in grids dominated by converter in-feed like in OWF. The authors are suggesting a new WT control concept that is characterized by voltage injection instead of the usage of an explicit current controller. Simulation results show that the voltage rise following islanding can be avoided, whereas the fault ride-through response to grid short circuits remains almost the same as before.
Autors: Istvan Erlich;Abdul Korai;Tobias Neumann;Masoumeh Koochack Zadeh;Steffen Vogt;Christoph Buchhagen;Cristian Rauscher;Andreas Menze;Jochen Jung;
Appeared in: IEEE Transactions on Energy Conversion
Publication date: Sep 2017, volume: 32, issue:3, pages: 1263 - 1271
Publisher: IEEE
 
» New High Step-Up Multilevel Converter Topology With Self-Voltage Balancing Ability and Its Optimization Analysis
Abstract:
In this paper, a new cascaded high step-up multilevel converter topology is designed, which is based on the series connection of several switched-capacitor submultilevel units. The voltage gain of proposed multilevel converter is related to the number of used switches-capacitor units. The main advantage of proposed topology is inherent voltage balancing of used capacitors. The proposed cascade topology is optimized to minimize the number of capacitors, power switches, and the value of voltage on switches for given levels. The proposed topology is compared with other high step-up multilevel converter topologies and conventional structures. The comparison results show that the presented structure requires the least number of switches and dc sources. Moreover, the voltage on the switches of proposed topology is low. In order to confirm the operation of proposed high step-up multilevel converter, both experimental and simulation works are provided.
Autors: Rasoul Shalchi Alishah;Seyed Hossein Hosseini;Ebrahim Babaei;Mehran Sabahi;Gevork B. Gharehpetian;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Sep 2017, volume: 64, issue:9, pages: 7060 - 7070
Publisher: IEEE
 
» New PTS Schemes for PAPR Reduction of OFDM Signals Without Side Information
Abstract:
In this paper, two partial transmit sequence (PTS) schemes without side information (SI) are proposed for reducing peak-to-average power ratio of orthogonal frequency division multiplexing signals. The proposed schemes do not transmit SI identifying a rotating vector because identifiable phase offset is applied to the elements of each rotating vector. To extract SI from the received signal and recover the data sequence, the maximum likelihood (ML) detector is used. This ML detector exploits the Euclidean distance between the given signal constellation and the signal constellation rotated by the phase offset. By doing pairwise error probability (PEP) analysis, it is investigated how to choose good phase offsets for embedding SI. Also, the performance degradation caused by SI detection failure is analyzed based on PEP. Finally, through numerical analysis, it is shown that the BER performance of the proposed PTS schemes is not degraded compared with the conventional PTS with perfect SI.
Autors: Hyun-Seung Joo;Kee-Hoon Kim;Jong-Seon No;Dong-Joon Shin;
Appeared in: IEEE Transactions on Broadcasting
Publication date: Sep 2017, volume: 63, issue:3, pages: 562 - 570
Publisher: IEEE
 
» New Simplest Exact Forms for the 3-D and 4-D Multivariate Rayleigh PDFs With Applications to Antenna Array Geometries
Abstract:
Determining tractable analytical expressions for the probability density functions (PDFs) of correlated Rayleigh random variables (i.e., the multivariate Rayleigh joint PDF) is a longstanding problem in wireless communications. Recent results have reported simpler forms for the 3-D and 4-D Rayleigh joint PDFs. Yet, the new solutions are still mathematically complex. New representations for the general 3-D Rayleigh and the general 4-D Rayleigh fading PDFs are derived. An advantage of the new representations is that only a single-integral computation is needed to compute the 3-D Rayleigh PDF and only double integral computation is needed for the 4-D Rayleigh PDF, where the integrals are proper and definite on and , respectively. The new expressions for the 3-D and 4-D Rayleigh PDFs are used to determine several special, “best” placements in the 2-D plane for three and four antennas. Closed-form solutions are found for three antennas with two or three independent antenna pairs, and four antennas with four or five independent antenna pairs.
Autors: Norman C. Beaulieu;Yixing Zhang;
Appeared in: IEEE Transactions on Communications
Publication date: Sep 2017, volume: 65, issue:9, pages: 3976 - 3984
Publisher: IEEE
 
» New Technique Trends for Power Converters in Distributed Power Generation Systems - Part I
Abstract:
This "Special Section on New Technique Trends for Power Converters in Distributed Power Generation Systems" of the IEEE Transactions on Industrial Electronics (TIE) 35 papers selected among 89 submitted papers. Therefore, this Special Section will be published in two parts. In Part I, all the papers are related to dc/ac grid-tied inverters.
Autors: Weimin Wu;Marco Liserre;Henry Shu-Hung Chung;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Sep 2017, volume: 64, issue:9, pages: 7399 - 7401
Publisher: IEEE
 
» New Trends in Smart Sensors for Industrial Applications - Part I
Abstract:
This "Special Section on New Trends in Smart Sensors for Industrial Applications" of the IEEE Transactions on Industrial Electronics, will be published in two issues of the journal. In this issue, the first 13 papers are presented. A brief summary of the papers is provided.
Autors: Stoyan Nihtianov;Zhichao Tan;Boby George;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Sep 2017, volume: 64, issue:9, pages: 7281 - 7283
Publisher: IEEE
 
» News from the Field
Abstract:
Autors: Lynette Jones;
Appeared in: IEEE Transactions on Haptics
Publication date: Sep 2017, volume: 10, issue:3, pages: 302 - 304
Publisher: IEEE
 
» Noise Analysis of Phase-Demodulating Receivers Employing Super-Regenerative Amplification
Abstract:
Growing interest in ultralow-power radio frequency receivers has reinvigorated research in super-regenerative amplifier (SRA) architectures, in part due to their ability to achieve enormous gain at very low power. Conventionally, SRAs have been paired with envelop detectors that demodulate amplitude-modulated signals (e.g., ON–OFF keying); mathematical models have been developed to predict the performance of such systems. Since modern communication applications require more spectrally efficiency modulation schemes, this paper develops a mathematical model that predicts the stochastic behavior of SRAs when used in phase-demodulating receivers. This stochastic model is then used to predict the sensitivity of a phase-demodulating receiver employing a Colpitts-based SRA. Results from the developed model are validated with measurements of a discrete prototype, illustrating that SRAs can be used with mixing to demodulate quadrature phase-shift keying signals with −88-dBm sensitivity when the SRA consumes 1.2 mA at 1.5 V at 45 MHz.
Autors: Dhon-Gue Lee;Patrick P. Mercier;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Sep 2017, volume: 65, issue:9, pages: 3299 - 3311
Publisher: IEEE
 
» Noise Cancelation? Explained!: The Role of Feedback in Noise-Canceling LNAs and Receivers
Abstract:
Inductorless wide-band low-noise amplifiers (LNAs) usually suffer from poor noise performance, mainly due to the high noise contribution of the matching device. Noise canceling (NC) is a technique used in wide-band LNAs [1]-[13] to nullify the noise contribution of the matching device at the output. NC techniques are often explained with the help of the block diagram shown in Figure 1(a), where the input signal from a source of internal impedance Rs is simultaneously fed to a matching amplifier and a voltage sensing amplifier.
Autors: Indrajit Das;Nagarjuna Nallam;
Appeared in: IEEE Microwave Magazine
Publication date: Sep 2017, volume: 18, issue:6, pages: 100 - 109
Publisher: IEEE
 
» Noise Figure Degradation in Balanced Amplifiers
Abstract:
Balanced amplifiers suffer from the noise figure performance in comparison with a stand-alone amplifier even with an ideal input divider. The noise parameters degrade further with an imperfect divider. We present exact and approximate analytical results for the noise figure and noise parameters of the balanced amplifier in divider topology. Measurement results are also presented as a verification.
Autors: Akif Alperen Coskun;Abdullah Atalar;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Sep 2017, volume: 27, issue:9, pages: 848 - 850
Publisher: IEEE
 
» Non-Asymptotic Analysis of $\ell _{1}$ -Norm Support Vector Machines
Abstract:
Support vector machines (SVMs) with the -penalty became a standard tool in the analysis of high-dimensional classification problems with sparsity constraints in many applications, including bioinformatics and signal processing. We give non-asymptotic results on the performance of -SVM in identification of sparse classifiers. We show that an -dimensional -sparse classification vector can be (with high probability) well approximated from only Gaussian trials. We derive similar estimates also in the presence of misclassifications and for the so-called doubly regularized SVM, which combines the - and the -penalty. Similar bounds were obtained earlier in the analysis of LASSO and 1-Bit compressed sensing.
Autors: Anton Kolleck;Jan Vybíral;
Appeared in: IEEE Transactions on Information Theory
Publication date: Sep 2017, volume: 63, issue:9, pages: 5461 - 5476
Publisher: IEEE
 
» Non-Foster Matched Antennas for High-Power Applications
Abstract:
A non-Foster matching network has been designed for a small cylindrical slot antenna, and its broadband matching capability has been examined at varying signal power levels. It has been observed that the non-Foster circuit (NFC) impedance changes considerably as the signal power increases, thus reducing its matching capability as well as introducing stability problems. To analyze its true advantage in transmit applications, the third-order intermodulation output intercept point (OIP3) and the gain-bandwidth product of the non-Foster matched antenna have been compared with the unmatched antenna, when both are attached to the same power amplifier. Simulations show that the unmatched antenna has a higher OIP3 and gain-bandwidth product, despite being more poorly matched. Although the OIP3 can be slightly improved by increasing the bias current of the NFC, improved linearization techniques should be studied to offset distortion effects in NFCs.
Autors: Minu M. Jacob;Daniel F. Sievenpiper;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Sep 2017, volume: 65, issue:9, pages: 4461 - 4469
Publisher: IEEE
 
» Non-Intrusive Reference Governors for Over-Actuated Linear Systems
Abstract:
The technical note presents the design of a reference governor that manages directly the state and input references for constrained output regulation problems. In particular, for the class of so-called weakly input redundant linear systems, the proposed method leads to a taxonomy in terms of non-intrusive and intrusive reference governors, on the basis of the effect of reference manipulation on the tracking error. Non-intrusive references constitute a degree of freedom that one can freely select to meet constraint requirements; intrusive references are also assignable during transient, but shall be forced to vanish in steady state in order to achieve exact regulation. A simulation study illustrates the features of the proposed approach in support of the theoretical findings.
Autors: Junqiang Zhou;Marcello Canova;Andrea Serrani;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Sep 2017, volume: 62, issue:9, pages: 4734 - 4740
Publisher: IEEE
 
» Non-Saturation Delay Analysis of Medium Transparent MAC Protocol for 60 GHz Fiber-Wireless Towards 5G mmWave Networks
Abstract:
In this paper, we demonstrate an analytical model for computing the end-to-end packet delay of a converged optical/wireless 60 GHz Radio-over-Fiber (RoF) network operating under the medium-transparent MAC (MT-MAC) protocol. For the calculation of the cycle times, this model considers the protocol time consumed for contention and data exchange over both optical and wireless media, a feature of the MT-MAC that effectively enables it to provide direct and seamless interaction between the RoF Central Office and the end users. This new analytical model enables us to conduct an extensive delay performance analysis of the various performance aspects of hybrid RoF networks operating under the fixed service paradigm, such as various optical capacity availability scenarios, varying load conditions, optical network ranges, transmission window lengths, and data packet sizes. The derived theoretical results present an excellent match with the respective simulation findings, providing sub millisecond latency values for a plethora of network conditions, confirming that the MT-MAC scheme can effectively be incorporated into the upcoming mm-wave 5G era.
Autors: George Kalfas;John Vardakas;Luis Alonso;Cristos Verikoukis;Nikos Pleros;
Appeared in: Journal of Lightwave Technology
Publication date: Sep 2017, volume: 35, issue:18, pages: 3945 - 3955
Publisher: IEEE
 
» Non-Uniform Aged Modules Reconfiguration for Large-Scale PV Array
Abstract:
In the past decades, a large number of photovoltaic (PV) plants have been built. Due to the minor physical differences between PV cells and the influence of environmental factors such as rains, temperature, and humidity, the aging of a PV array is often distributed unevenly within each PV module. This non-uniform aging causes further decreased output power, which is often easily observed for large size PV arrays. Although the global maximum power point tracking (GMPPT) strategy can improve the output power, the GMPPT cannot exploit the maximal power generation potential from non-uniform aging PV arrays. In order to exploit further the power generation potential and extend the service time of non-uniform aging PV arrays, a novel PV array reconfiguration method is developed in this paper. The concept of cell unit is applied to investigate the aging phenomenon of PV modules, and each PV module is assumed to be composed of three submodules, while these three submodules within any single PV module might have different aging conditions and, thus, different power-output capacities. The challenge is how to rearrange the PV array under the cases where: 1) each PV module has non-uniformly aged cell units; 2) there are a large number of PV modules; and 3) the voltage working range is restricted. To solve these problems, a nonlinear integer programming problem is formulated to maximize the power output under the constraints of non-uniformly aging and voltage restrictions. A small size PV array is simulated to illustrate the proposed method. Furthermore, medium size and large size PV arrays are employed to verify the feasibility of the proposed method. A 1.5 kW real PV array under non-uniform aging conditions is presented and experimentally tested to confirm the proposed rearrangement method.
Autors: Yihua Hu;Jiangfeng Zhang;Peng Li;Dongsheng Yu;Lin Jiang;
Appeared in: IEEE Transactions on Device and Materials Reliability
Publication date: Sep 2017, volume: 17, issue:3, pages: 560 - 569
Publisher: IEEE
 
» Noninvasive Personalization of a Cardiac Electrophysiology Model From Body Surface Potential Mapping
Abstract:
Goal: We use noninvasive data (body surface potential mapping, BSPM) to personalize the main parameters of a cardiac electrophysiological (EP) model for predicting the response to different pacing conditions. Methods: First, an efficient forward model is proposed, coupling the Mitchell–Schaeffer transmembrane potential model with a current dipole formulation. Then, we estimate the main parameters of the cardiac model: activation onset location and tissue conductivity. A large patient-specific database of simulated BSPM is generated, from which specific features are extracted to train a machine learning algorithm. The activation onset location is computed from a Kernel Ridge Regression and a second regression calibrates the global ventricular conductivity. Results: The evaluation of the results is done both on a benchmark dataset of a patient with premature ventricular contraction (PVC) and on five nonischaemic implanted cardiac resynchonization therapy (CRT) patients with a total of 21 different pacing conditions. Good personalization results were found in terms of the activation onset location for the PVC (mean distance error, MDE = 20.3 mm), for the pacing sites (MDE = 21.7 mm) and for the CRT patients (MDE = 24.6 mm). We tested the predictive power of the personalized model for biventricular pacing and showed that we could predict the new electrical activity patterns with a good accuracy in terms of BSPM signals. Conclusion: We have personalized the cardiac EP model and predicted new patient-specific pacing conditions. Significance: This is an encouraging first step towards a noninvasive preoperative prediction of the response to different pacing conditions to assist clinicians for CRT patient selection and therapy planning.
Autors: Sophie Giffard-Roisin;Thomas Jackson;Lauren Fovargue;Jack Lee;Hervé Delingette;Reza Razavi;Nicholas Ayache;Maxime Sermesant;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Sep 2017, volume: 64, issue:9, pages: 2206 - 2218
Publisher: IEEE
 
» Nonlinear Compensation Assessment in Few-Mode Fibers via Phase-Conjugated Twin Waves
Abstract:
In this paper, we further explore the concept of phase-conjugated twin waves (PCTW) for nonlinear cancellation in space-division multiplexed (SDM) systems. Previously, we demonstrated that the PCTW technique can successfully provide nonlinear cancellation in SDM systems. In this paper, we investigate the cases where two and four spatial modes are copropagating in a multimode fiber, considering three link lengths (1000, 3200, and 8000 km). Weak- and strong-coupling regimes are also evaluated. Our numerical simulation results show an average performance improvement 10 dB after a 1000 km transmission link.
Autors: Joana S. Tavares;Luis M. Pessoa;Henrique M. Salgado;
Appeared in: Journal of Lightwave Technology
Publication date: Sep 2017, volume: 35, issue:18, pages: 4072 - 4078
Publisher: IEEE
 
» Nonlinear Mitigation of a 400G Frequency-Hybrid Superchannel for the 62.5-GHz Slot
Abstract:
We propose a 400G frequency-hybrid superchannel solution based on three carriers, two edge PM-16QAM, and a central PM-64QAM carrier, compatible with the 62.5-GHz grid slot (spectral efficiency of 6.4 b/s/Hz). The proposed superchannel is experimentally assessed in long-haul transmission by copropagation with other eight similar superchannels. The optimum power ratio between superchannel carriers is analytically determined in linear and nonlinear operation regimes using the enhanced Gaussian noise model and validated by experimental and simulation results. The 400G superchannel performance is evaluated in terms of maximum reach determining the optimum launch power and considering three distinct forward-error correction (FEC) paradigms: superchannel FEC (SC-FEC) where a single FEC is applied to the entire superchannel, independent carrier FEC (IC-FEC) where an independent FEC with fixed overhead is applied to each superchannel carrier, and independent carrier flexible FEC (Flex-FEC) where optimized FEC overheads are applied independently to each superchannel carrier with the constraint of a given total overhead. When compared to the IC-FEC approach, the SC-FEC or Flex-FEC approaches enable to extend the maximum transmission distance by more than 60%, while reducing the optimum power ratio by 6 dB, at the cost of 2 dB higher launched power. The system performance is also analyzed for the case of nonlinear compensation via digital backpropagation (DBP) techniques, assessing the improvement in reach and evaluating their impact on the optimum power ratio and launch power. For the proposed frequency-hybrid superchannel, we demonstrate that the application of DBP can be restricted to the carrier with higher QAM cardinality, thereby significantly reducing the overall computational effort, with a maximum reach reduction of- only 2% over the application of DBP to all three carriers individually.
Autors: Sofia B. Amado;Fernando P. Guiomar;Nelson J. Muga;Antonino Nespola;Luca Bertignono;Andrea Carena;Armando Nolasco Pinto;
Appeared in: Journal of Lightwave Technology
Publication date: Sep 2017, volume: 35, issue:18, pages: 3963 - 3973
Publisher: IEEE
 
» Nonlinear Sparse Hashing
Abstract:
To facilitate fast similarity search, this paper proposes to encode the nonlinear similarity and image structure as compact binary codes. Rather than adopting single matrix as projection in the literature, we employ a nonlinear transformation in the form of multilayer neural network to generate binary codes to capture the local structure between data samples. Specifically, we train the network such that the quantization loss is minimized and the variance over all bits is maximized. In addition, we capture the salient structure of image samples at the abstract level with sparsity constraint and inherit the generalization power to unseen samples. Furthermore, we incorporate the supervisory label information into the learning procedure to take advantage of the manual label. To obtain the desired binary codes and the parameterized nonlinear transformation, we optimize the formulated objective problem over each variable with an iterative alternating method. To validate the efficacy of the proposed hashing approach, we conduct experiments on three widely used datasets, namely CIFAR10, MNIST, and SUN397, by comparing with several recent proposed hashing methods.
Autors: Zhixiang Chen;Jiwen Lu;Jianjiang Feng;Jie Zhou;
Appeared in: IEEE Transactions on Multimedia
Publication date: Sep 2017, volume: 19, issue:9, pages: 1996 - 2009
Publisher: IEEE
 
» Nonlocal Gradient Sparsity Regularization for Image Restoration
Abstract:
Total variation (TV) regularization is widely used in image restoration to exploit the local smoothness of image content. Essentially, the TV model assumes a zero-mean Laplacian distribution for the gradient at all pixels. However, real-world images are nonstationary in general, and the zero-mean assumption of pixel gradient might be invalid, especially for regions with strong edges or rich textures. This paper introduces a nonlocal (NL) extension of TV regularization, which models the sparsity of the image gradient with pixelwise content-adaptive distributions, reflecting the nonstationary nature of image statistics. Taking advantage of the NL similarity of natural images, the proposed approach estimates the image gradient statistics at a particular pixel from a group of nonlocally searched patches, which are similar to the patch located at the current pixel. The gradient data in these NL similar patches are regarded as the samples of the gradient distribution to be learned. In this way, more accurate estimation of gradient is achieved. Experimental results demonstrate that the proposed method outperforms the conventional TV and several other anchors remarkably and produces better objective and subjective image qualities.
Autors: Hangfan Liu;Ruiqin Xiong;Xinfeng Zhang;Yongbing Zhang;Siwei Ma;Wen Gao;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Sep 2017, volume: 27, issue:9, pages: 1909 - 1921
Publisher: IEEE
 
» Nonlocal-Similarity-Based Sparse Coding for Hyperspectral Imagery Classification
Abstract:
For hyperspectral imagery (HSI) classification, many works have shown the effectiveness of the spectral–spatial method. However, some previous works using neighboring information assumed that all neighboring pixels make an equal contribution to the central pixel, which is unreasonable for heterogeneous pixels, especially near the boundary of a region. In this letter, a nonlocal self-similarity based on the sparse coding method, followed by the use of a support vector machine classifier, is proposed to improve classification performance. Inspired by the success of nonlocal means, a new nonlocal weighted method is developed to determine the relationship between a test pixel and its neighboring ones. The nonlocal weights are determined by using the spectral angle mapper algorithm, which can exploit the spectral information of surface features. The experiments validate the superiority of our proposed method over existing approaches for HSI classification.
Autors: Jing Bai;Wenhao Zhang;Zhenzhen Gou;Licheng Jiao;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Sep 2017, volume: 14, issue:9, pages: 1474 - 1478
Publisher: IEEE
 
» Nonmonotonic Front Propagation on Weighted Graphs With Applications in Image Processing and High-Dimensional Data Classification
Abstract:
In this paper, we propose an adaptation of partial difference equations (PDEs) level set method for nonmonotonic front propagation on weighted graphs. This adaptation leads to a PDE, whose coefficients are data geometry dependent. Our motivation is to extend their applications to any discrete data that can be represented by a weighted graph. This paper follows several preliminaries of our works, and introduces several significant improvements: A simplified and explicit representation of a front on a weighted graph, a new formulation of the level set equation on weighted graphs considering both time-dependent and stationary versions of this equation in the case of signed velocities, and an efficient algorithm that generalized the fast marching to graphs with signed velocities. We propose to use this method for image processing and for high-dimensional data classification.
Autors: Xavier Desquesnes;Abderrahim Elmoataz;
Appeared in: IEEE Journal of Selected Topics in Signal Processing
Publication date: Sep 2017, volume: 11, issue:6, pages: 897 - 907
Publisher: IEEE
 
» Nonparametric Bayesian Analysis for Masked Data From Hybrid Systems in Accelerated Lifetime Tests
Abstract:
Under constant stress accelerated test, we analyze the masked data from hybrid systems including series–parallel system and parallel–series system. The Bayesian posterior distribution and estimates of components’ subsurvival functions are obtained by assuming a prior of the multivariate Dirichlet process. By establishing a relationship between subsurvival and survival functions of components, the estimates of reliabilities for components and system are derived from the estimates of subsurvival functions. It is not confined to the common restriction that the sets of discontinuity points of the survival functions have to be disjointed. For a complex system, we represent it to the proposed series–parallel system or parallel–series system. Thus, the nonparametric Bayesian approach is also applicable for the complex system with s-independent components. A simulated example is presented to demonstrate the efficiency of the method. Finally, the method is applied to a real data of coal wine monitoring power.
Autors: Bin Liu;Yimin Shi;Jing Cai;Xuchao Bai;Chunfang Zhang;
Appeared in: IEEE Transactions on Reliability
Publication date: Sep 2017, volume: 66, issue:3, pages: 662 - 676
Publisher: IEEE
 
» Nonprecious Electrocatalysts for Li?Air and Zn?Air Batteries: Fundamentals and recent advances.
Abstract:
Over their 150-year history, new twists on metal-air batteries have continued to emerge up to the present day. In this article, we present the fundamentals and recent advances in nonprecious electrocatalysts for metal-air batteries. The catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in lithium (Li)-air and zinc (Zn)-air batteries, including transition-metal oxides, inorganic-organic hybrid materials, and metal-free materials, are summarized. Both aqueous and nonaqueous systems are also considered. We briefly introduce the mechanism and challenges of oxygen electrochemistry and provide a perspective on the design and development of nonprecious electrocatalysts.
Autors: Tongwen Yu;Jing Fu;Rui Cai;Aiping Yu;Zhongwei Chen;
Appeared in: IEEE Nanotechnology Magazine
Publication date: Sep 2017, volume: 11, issue:3, pages: 29 - 55
Publisher: IEEE
 
» Novel Annular Flow Electromagnetic Measurement System for Drilling Engineering
Abstract:
Downhole micro-flux control drilling technology can effectively solve drilling accidents, such as kick and loss in narrow density window drilling scenarios. Using a downhole annular flow measurement system to obtain real-time information of downhole annular flow is the core and foundation of downhole micro-flux control drilling technology. The research work of electromagnetic flowmeters in recent years creates a challenge for downhole annular flow measurement. This paper proposes a new method for an annular flow measurement system based on the electromagnetic induction principle. First, the annular flow measuring principle, the weight function, the density of virtual current, and the magnetic field of the annular flow electromagnetic measurement system are described. Second, the basic design of the annular flow electromagnetic measurement system is described. Third, model simulation and dynamic experiments on an annular flow electromagnetic measurement system are carried out. The simulation and experimental results show a linear relationship between the system output and the annular flow rate, and also verify the correctness of annular flow electromagnetic measurement theory.
Autors: Liang Ge;Guohui Wei;Qing Wang;Ze Hu;Junlan Li;
Appeared in: IEEE Sensors Journal
Publication date: Sep 2017, volume: 17, issue:18, pages: 5831 - 5839
Publisher: IEEE
 
» Novel Bayesian Inference Algorithms for Multiuser Detection in M2M Communications
Abstract:
The fifth generation and future wireless networks are expected to support massive machine-to-machine (M2M) communications. Due to the sporadic nature, massive M2M communications can be well supported by low-activity code division multiple access (LA-CDMA). In the literature, maximum a posteriori detector has been proposed to detect the active users in LA-CDMA when the user activity factor is known and small. However, such user activity factor is usually unknown and could be large in practice, which makes the multiuser detection for LA-CDMA a challenging task. In this paper, we first formulate the LA-CDMA uplink using single measurement vector (SMV) model and multiple measurement vector (MMV) model, then, propose novel Bayesian inference algorithms to recover the transmitted signals. For SMV model, we first introduce sparse Bayesian learning (SBL) that exploits the sparsity of the transmitted signals, then, add on the known finite-alphabet constraints and introduce Gaussian mixture model method to recover the transmitted signals. For MMV model, pattern coupled SBL (PCSBL) algorithm is introduced that takes into consideration the neighbor coherence of each device, then the block SBL is introduced through exploiting the row sparsity property and the column coherence of each device. The four Bayesian inference methods make use of various priors and hyperparameters, which can be autonomously learned through the training process via expectation maximization (EM) or variational EM iterative algorithms. Furthermore, the proposed Bayesian methods do not require the knowledge of user activity factor. Simulation results have shown that the proposed Bayesian inference methods outperform the classical algorithms.
Autors: Xiaoxu Zhang;Ying-Chang Liang;Jun Fang;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Sep 2017, volume: 66, issue:9, pages: 7833 - 7848
Publisher: IEEE
 
» Novel Histogram Based Unsupervised Classification Technique to Determine Natural Classes From Biophysically Relevant Fit Parameters to Hyperspectral Data
Abstract:
Hyperspectral image analysis has benefited from an array of methods that take advantage of the increased spectral depth compared to multispectral sensors; however, the focus of these developments has been on supervised classification methods. Lack of a priori knowledge regarding land cover characteristics can make unsupervised classification methods preferable under certain circumstances. An unsupervised classification technique is presented that utilizes physically relevant basis functions to model the reflectance spectra. These fit parameters used to generate the basis functions allow clustering based on spectral characteristics rather than spectral channels and provide both noise and data reduction. Histogram splitting of the fit parameters is then used as a means of producing an unsupervised classification. Unlike current unsupervised classification techniques that rely primarily on Euclidian distance measures to determine similarity, the unsupervised classification technique uses the natural splitting of the fit parameters associated with the basis functions creating clusters that are similar in terms of physical parameters. The data set used in this work utilizes the publicly available data collected at Indian Pines, Indiana. This data set provides reference data allowing for comparisons of the efficacy of different unsupervised data analysis. The unsupervised histogram splitting technique presented in this paper is shown to be better than the standard unsupervised ISODATA clustering technique with an overall accuracy of 34.3/19.0% before merging and 40.9/39.2% after merging. This improvement is also seen as an improvement of kappa before/after merging of 24.8/30.5 for the histogram splitting technique compared to 15.8/28.5 for ISODATA.
Autors: Cooper McCann;Kevin S. Repasky;Mikindra Morin;Rick L. Lawrence;Scott Powell;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Sep 2017, volume: 10, issue:9, pages: 4138 - 4148
Publisher: IEEE
 
» Novel Hybrid LLC Resonant and DAB Linear DC–DC Converter: Average Model and Experimental Verification
Abstract:
A novel hybrid LLC resonant and dual active bridge (DAB) linear dc–dc converter is proposed as bus converter, which can achieve soft switching and constant output voltage gain at both the open-loop light load and closed-loop heavy load conditions. This paper focuses on its continuous-time average modeling in detail based on the dc output voltage, the first order terms of two transformer currents and the resonant capacitor voltage, which results in a seven-order model. Additionally, the total control-to-output transfer function is derived for the proposed hybrid converter dynamic analysis. The experimental results have verified that the proposed model can correctly match the small-signal frequency response, and compare with DAB, the related analysis based on the proposed model shows the novel hybrid converter can have a better output voltage response.
Autors: Chuang Liu;Haiyang Liu;Guowei Cai;Shumei Cui;Haijun Liu;Hang Yao;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Sep 2017, volume: 64, issue:9, pages: 6970 - 6978
Publisher: IEEE
 
» Novel Insight Into Multi-User Channels with Multi-Antenna Users
Abstract:
Multi-user channels with single-antenna users have proven to be favorable in massive multiple-input multiple-output regime as the asymptotic orthogonality of different channel vectors. However, the orthogonality of the channel maybe no longer holds for more general case. In this letter, we consider the scenario, where a base station equipped with antennas that simultaneously serves independent multi-antenna users. The orthogonality of channel vectors is examined in both spatially correlated Rayleigh channels and geometry-based channels. The theoretical analysis shows that the correlation matrix of the generalized channel in both cases will not become diagonal, which means that the favorable propagation decays when grows without limit. A novel insight is then derived in the case of multi-antenna users for the more general channels that the inner-user interference still exists when . However, the analysis of the geometry-based channel indicates that the inter-user interference can still be eliminated by the large array effect.
Autors: Xiaoyong Wu;Danpu Liu;
Appeared in: IEEE Communications Letters
Publication date: Sep 2017, volume: 21, issue:9, pages: 1961 - 1964
Publisher: IEEE
 
» Novel Substrate Integrated Waveguide Filtering Crossover Using Orthogonal Degenerate Modes
Abstract:
A novel substrate integrated waveguide (SIW) filtering crossover is presented based on the orthogonal degenerate TE201 and TE102 modes in SIW square cavities. By arranging the feeding ports and coupling windows at the cavity center, excellent transmission and isolation responses can be achieved successfully. In addition, the bandwidth of the crossover can be easily controlled using the well-established coupling matrix synthesis method, and the maximum bandwidth is determined by the acceptable isolation levels. A prototype operating at 20 GHz was designed and fabricated to verify this concept, and the measured results are in excellent agreement with the simulation results.
Autors: Si-Qi Han;Kang Zhou;Jin-Dong Zhang;Chun-Xia Zhou;Wen Wu;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Sep 2017, volume: 27, issue:9, pages: 803 - 805
Publisher: IEEE
 
» nROAR: Near Real-Time Opportunistic Spectrum Access and Management in Cloud-Based Database-Driven Cognitive Radio Networks
Abstract:
Cognitive radio network with spectrum sensing to find idle channels and access them opportunistically is regarded as an emerging technology to deal with spectrum scarcity caused by exclusive licensing to primary systems. Simulation-based studies loose practical relevance due to assumptions and usage of simple models for defining transmission regions, multi-path propagation, and traffic intensity. In this paper, we present an experimental study for near real-time spectrum sensing and opportunistic spectrum access in database-driven cognitive radio networks (nROAR) using national instrument USRP devices in wide-band regime. We present numerical results for evaluating spectrum sensing using adaptive threshold-based joint energy and bandwidth detection. Furthermore, we evaluate the dynamic spectrum access using database-driven quorum-based rendezvous for opportunistic access for admitted unlicensed secondary users in diverse wireless bands. The proposed nROAR architecture addresses challenges related to providing spectrum access which require fast processing of a large number of spectrum-sensing measurements across diverse wireless bands, geography, and time.
Autors: Danda B. Rawat;Chandra Bajracharya;Sean Grant;
Appeared in: IEEE Transactions on Network and Service Management
Publication date: Sep 2017, volume: 14, issue:3, pages: 745 - 755
Publisher: IEEE
 
» Numerical Analysis of 2-D and 3-D MHD Flows Relevant to Fusion Applications
Abstract:
The analysis of many fusion applications such as liquid-metal blankets requires application of computational fluid dynamics (CFD) methods for electrically conductive liquids in geometrically complex regions and in the presence of a strong magnetic field. A current state of the art general purpose CFD code allows modeling of the flow in complex geometric regions, with simultaneous conjugated heat transfer analysis in liquid and surrounding solid parts. Together with a magnetohydrodynamics (MHD) capability, the general purpose CFD code will be a valuable tool for the design and optimization of fusion devices. This paper describes an introduction of MHD capability into the general purpose CFD code CFX, part of the ANSYS Workbench. The code was adapted for MHD problems using a magnetic induction approach. CFX allows introduction of user-defined variables using transport or Poisson equations. For MHD adaptation of the code three additional transport equations were introduced for the components of the magnetic field, in addition to the Poisson equation for electric potential. The Lorentz force is included in the momentum transport equation as a source term. Fusion applications usually involve very strong magnetic fields, with values of the Hartmann number of up to tens of thousands. In this situation a system of MHD equations become very rigid with very large source terms and very strong variable gradients. To increase system robustness, special measures were introduced during the iterative convergence process, such as linearization using source coefficient for momentum equations. The MHD implementation in general purpose CFD code was tested against benchmarks, specifically selected for liquid-metal blanket applications. Results of numerical simulations using present implementation closely match analytical solutions for a Hartmann number of up to 1500 for a 2-D laminar flow in the duct of square cross section, with conducting and nonconducting walls. Results for a 3-D te- t case are also included.
Autors: Andrei Khodak;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Sep 2017, volume: 45, issue:9, pages: 2561 - 2565
Publisher: IEEE
 
» Numerical Investigation of High-Voltage Partial Buried P/N-Layer SOI LDMOS
Abstract:
High-voltage lateral double-diffused MOSFETs with partial buried P/N-type silicon layers (PBPL/PBNL) in silicon-on-insulator (SOI) technology are investigated numerically. In the lateral direction, the partial buried silicon layer (PBL) can introduce an additional electric field peak, which improves the surface electric field distribution and increases the charge accommodation in the drift region. Consequently, in the vertical direction, PBPL and PBNL can both induce higher electric field into the buried-oxide layer, and thus enhance the breakdown voltage (BV) significantly. Due to the higher electron concentration in the drift region, the ON-resistance () can be also reduced remarkably. The 2-D simulation results show that PBPL and PBNL SOIs can achieve BVs of 296 and 365 V, respectively, in comparison to the conventional SOI (BV ~ 225 V) and the buried N-layer SOI (BV ~ 231 V). In addition, by comparison with the conventional SOI, can be reduced about 31.7% and 13.8% for PBPL and PBNL SOIs, respectively. Finally, hybrid PBPL/PBNL SOIs are studied and shown to be capable of further improving the device performance.
Autors: Yue Hu;Yanfei Gong;Huazhen Liu;Qianqian Xu;Wen-Sheng Zhao;Jing Wang;Ying Wang;Gaofeng Wang;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Sep 2017, volume: 64, issue:9, pages: 3725 - 3733
Publisher: IEEE
 
» Numerical Modeling of Magnetic Nanoparticle and Carrier Fluid Interactions Under Static and Double-Shear Flows
Abstract:
Magnetic nanoparticles are widely utilized in smart materials, the most well-known application being magnetorheological fluids. In this paper, a comprehensive numerical model of magnetic nanoparticles and the carrier fluid interactions is presented. The soft sphere model approach is adopted to simulate the nanoparticle interactions at a coarse molecular level, with the consideration of both contact and noncontact particle interactions. Magnetic dipole theory is used to simulate the particle behavior under external magnetic fields. The carrier fluid flow is solved using the computational fluid dynamics approach with a two-way coupling with the nanoparticles. Based on the present model, simulations have been conducted for both static fluid and dynamic double-shear flow cases. Without the presence of an external magnetic field, local particle clusters are formed as a result of van der Waals attraction between the particles. When the external magnetic field is present, chain-like structures of nanoparticles are observed for both the static and dynamic cases parallel to the direction of the applied magnetic field. For the static case, the formation of the chain-like structures is rapid, and “steady state” is reached within a short time (∼1 ms). In the double-shear flow case, the chain-like structures are found to be much thinner and shorter than the static case. The developed model provides a fundamental understanding of the real physics of magnetic nanoparticles and carrier fluid interactions. It also enables future investigations in optimizing physical and transport properties of smart materials.
Autors: Dezheng Darson Li;Guan H. Yeoh;Victoria Timchenko;Heung-Fai Lam;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Sep 2017, volume: 16, issue:5, pages: 798 - 805
Publisher: IEEE
 
» Object Detection and Recognition for Assistive Robots: Experimentation and Implementation
Abstract:
Technological advances are being made to assist humans in performing ordinary tasks in everyday settings. A key issue is the interaction with objects of varying size, shape, and degree of mobility. Autonomous assistive robots must be provided with the ability to process visual data in real time so that they can react adequately for quickly adapting to changes in the environment. Reliable object detection and recognition is usually a necessary early step to achieve this goal. In spite of significant research achievements, this issue still remains a challenge when real-life scenarios are considered. In this article, we present a vision system for assistive robots that is able to detect and recognize objects from a visual input in ordinary environments in real time. The system computes color, motion, and shape cues, combining them in a probabilistic manner to accurately achieve object detection and recognition, taking some inspiration from vision science. In addition, with the purpose of processing the input visual data in real time, a graphical processing unit (GPU) has been employed. The presented approach has been implemented and evaluated on a humanoid robot torso located at realistic scenarios. For further experimental validation, a public image repository for object recognition has been used, allowing a quantitative comparison with respect to other state-of-the-art techniques when realworld scenes are considered. Finally, a temporal analysis of the performance is provided with respect to image resolution and the number of target objects in the scene.
Autors: Ester Martinez-Martin;Angel P. del Pobil;
Appeared in: IEEE Robotics & Automation Magazine
Publication date: Sep 2017, volume: 24, issue:3, pages: 123 - 138
Publisher: IEEE
 
» Object Localization Based on Proposal Fusion
Abstract:
Traditional regression framework of object locali-zation such as Overfeat often suffers from the problem of inaccurate scoring due to the separate scoring of classification network and regression network upon inconsistent regions. To tackle this problem, in this paper, we propose a novel object localization framework based on multiple complementary region proposal methods from the view of classification rather than regression. On top of our framework, we first combine multiple complementary region proposals during both training and testing as a means of data augmentation to generate more dense and reliable proposals for fusion, then achieve optimal compromise between complexity and efficiency through category clustering for bounding box sharing among similar categories, and finally propose a dense proposal fusion approach to merge dense region proposals near true object for fine-tuning of the final bounding box's coordinates and updating the confidence of fused proposals for final decision. Extensive experiments on the well-known large scale ILSVRC 2015 LOC dataset verify the effectiveness of our object localization framework.
Autors: Sheng Tang;Yu Li;Lixi Deng;Yongdong Zhang;
Appeared in: IEEE Transactions on Multimedia
Publication date: Sep 2017, volume: 19, issue:9, pages: 2105 - 2116
Publisher: IEEE
 
» Objective Video Quality Assessment Based on Perceptually Weighted Mean Squared Error
Abstract:
Object quality assessment for compressed video is critical to various video compression systems that are essential in the video delivery and storage. Although mean squared error (MSE) is computationally simple, it may not be accurate to reflect the perceptual quality of compressed videos, which are also affected dramatically by the characteristics of the human visual system (HVS), such as contrast sensitivity, visual attention, and masking effect. In this paper, a video quality metric is proposed based on perceptually weighted MSE. A low-pass filter is designed to model the contrast sensitivity of the HVS with the consideration of visual attention. The imperceptible distortion is adaptively removed in the salient and nonsalient regions. To quantitatively measure the masking effect, the randomness of video content is proposed in both the spatial and temporal domains. Since the masking effect highly depends on the regularity of structure and motion in the spatial and temporal directions, the video signal is modeled as a linear dynamic system, and the prediction error of future frames from previous frames is used as randomness to measure the significance of masking. The relation is investigated between MSE and perceptual quality scores across various contents, and a masking modulation model is proposed to compensate the impact of the masking effect on the MSE. The performance of the proposed quality metric is validated on three video databases with various compression distortions. The experimental results demonstrate that the proposed algorithm outperforms other benchmark quality metrics.
Autors: Sudeng Hu;Lina Jin;Hanli Wang;Yun Zhang;Sam Kwong;C.-C. Jay Kuo;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Sep 2017, volume: 27, issue:9, pages: 1844 - 1855
Publisher: IEEE
 
» Observation of Nonlinear Harmonic Generation of Bulk Modes in SAW Devices
Abstract:
Nonlinear generation of harmonics is measured on the wafer level on temperature compensated surface-acoustic-wave resonators on lithium niobate. The second-harmonic response features strong peaks looking like multiple resonant modes. The product of the frequency difference between the successive peaks to the substrate thickness is found to remain almost constant. The results also show that the level of the harmonic signal strongly depends on the roughness of the back side of the substrate. Due to these findings, it was assumed that the signal is due to nonlinear generation of a bulk mode. This assumption is confirmed experimentally by measuring the second-harmonic wave field on the back side of the substrate with an interferometer. Possible nonlinear mechanisms explaining these results are discussed.
Autors: Marc Solal;Kimmo Kokkonen;Shogo Inoue;Jean-Bernard Briot;Benjamin P. Abbott;Kevin J. Gamble;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Sep 2017, volume: 64, issue:9, pages: 1361 - 1367
Publisher: IEEE
 
» OGCMAC: A Novel OFDM Based Group Contention MAC for VANET Control Channel
Abstract:
The IEEE 1609.4 standard suggests that the control channel (CCH) should be devoted to the beacon delivery, where the multiple access control (MAC) plays an important role in scheduling the network resources to multiple nodes. This paper proposes a novel OFDM-based group contention MAC (OGCMAC) for vehicular ad hoc networks (VANETs), in which a new CCH architecture, a modified multi-carrier burst contention (MCBC) and a group contention strategy are established. The CCH architecture is proposed to reduce the resource consumption of contention windows (CWs). Based on the proposed architecture, MCBC is modified to adapt to VANETs. The proposed CCH architecture supports parallel contention mechanisms and allows losers to change their target resource blocks (RBs) during the modified MCBC. Furthermore, to accelerate the RB assignment, a group contention strategy is developed by dividing the entire frame into several groups with different sizes. With the objective to maximize the ratio of the RBs allocated free of collisions within a single frame, a greedy group partition algorithm is proposed to determine the appropriate group sizes according to the MCBC capability. Evaluations are done to validate the proposed mechanism. Results show that OGCMAC achieves the highest throughput among all the evaluated MACs, because of its high channel usage rate. RBs are allocated faster by employing the proposed optimal group contention policy. It is also shown that the proposed greedy group partition algorithm can reduce the resource waste by properly adopting the existing CWs without extra resource consumption.
Autors: Yi Cao;Haixia Zhang;Dalei Wu;Dongfeng Yuan;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Sep 2017, volume: 16, issue:9, pages: 5796 - 5809
Publisher: IEEE
 
» Oily Wastewater Treatment by Nano-TiO2-Induced Photocatalysis: Seeking more efficient and feasible solutions.
Abstract:
Oil is one our most important energy sources However, the wide use of oil could lead to diverse environmental problems, such as oily wastewater discharge. Oily wastewater is water that has become contaminated through oil and gas production, the refinery process, transportation, or storage. The dispersion and dissolution of oil fractions into water result in its contamination with free oil and grease, aliphatic hydrocarbons, aromatic hydrocarbons (e.g., benzene, toluene, ethylbenzene, and xylenes, known as BTEX), phenols, polycyclic aromatic hydrocarbons (PAHs), and highly soluble organic compounds (e.g., carboxyl acids. Many of these components are toxic, persistent, and bioaccumulative, posing a threat to ecosystems and human beings [6]-[9]. Thus, efficient treatment of oily wastewater is a necessity.
Autors: Bo Liu;Bing Chen;Baiyu Zhang;
Appeared in: IEEE Nanotechnology Magazine
Publication date: Sep 2017, volume: 11, issue:3, pages: 4 - 15
Publisher: IEEE
 
» On ${\mathcal H}_{\infty }$ Finite-Horizon Filtering Under Stochastic Protocol: Dealing With High-Rate Communication Networks
Abstract:
This paper is concerned with the filtering problem for a class of time-varying nonlinear delayed system under high-rate communication network and stochastic protocol (SP). The communication between the sensors and the state estimator is implemented via a shared high-rate communication network in which multiple transmissions are generated between two adjacent sampling instants of sensors. At each transmission instant, only one sensor is allowed to get access to the communication network in order to avoid data collisions and the SP is employed to determine which sensor obtains access to the network at a certain instant. The mapping technology is applied to characterize the randomly switching behavior of the data transmission resulting from the utilization of the SP. The aim of the problem addressed is to design an estimator such that the disturbance attenuation level is guaranteed for the estimation error dynamics over a given finite horizon. Sufficient conditions are derived for the existence of the finite-horizon filter satisfying the prescribed performance requirement, and the explicit expression of the time-varying filter gains is characterized by resorting to a set of recursive matrix inequalities. Simulation results demonstrate the effectiveness of the proposed filter design scheme.
Autors: Lei Zou;Zidong Wang;Jun Hu;Huijun Gao;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Sep 2017, volume: 62, issue:9, pages: 4884 - 4890
Publisher: IEEE
 
» On Artificial-Noise-Aided Transmit Design for Multiuser MISO Systems With Integrated Services
Abstract:
This paper considers artificial noise (AN) aided transmit designs for multiuser MISO systems in the eyes of service integration. Specifically, we combine two sorts of services, and serve them simultaneously: one multicast message intended for all receivers and one confidential message intended for only one receiver. The confidential message is kept perfectly secure from all the unauthorized receivers. Our goal is to jointly design the optimal input covariances for the multicast message, confidential message, and AN, such that the achievable secrecy rate region is maximized subject to the sum power constraint. This secrecy rate region maximization (SRRM) problem is a nonconvex vector maximization problem. To handle it, we reformulate the SRRM problem into a provably equivalent scalar optimization problem and propose a searching method to find all of its Pareto optimal points. The equivalent scalar optimization problem is identified as a secrecy rate maximization (SRM) problem with the quality of multicast service (QoMS) constraints. Further, we show that this equivalent QoMS-constrained SRM problem, albeit nonconvex, can be efficiently handled based on a two-stage optimization approach, including solving a sequence of semidefinite programs (SDPs). Moreover, we also extend the SRRM problem to an imperfect channel state information (CSI) case where a worst case robust formulation is considered. In particular, while transmit beamforming is generally a suboptimal technique to the SRRM problem, we prove that it is optimal for the confidential message transmission whether in the perfect CSI scenario or in the imperfect CSI scenario. For implementation efficiency, we also analyze the computational complexity of our proposed methods and put forward two suboptimal schemes and two possible extensions. Finally, numerical results demonstrate that the AN-aided transmit designs are effective in expanding the achievable secrecy rate regions, and that the suboptimal strategies can - chieve near-optimal performance.
Autors: Weidong Mei;Zhi Chen;Lingxiang Li;Jun Fang;Shaoqian Li;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Sep 2017, volume: 66, issue:9, pages: 8179 - 8195
Publisher: IEEE
 
» On BATS Codes With Variable Batch Sizes
Abstract:
BATS codes are a class of low complexity random linear network codes with high throughput. In a previous work, BATS codes were generalized to incorporate batches of different sizes, and a sufficient condition was obtained such that the belief propagation decoding can recover a given fraction of the input packets with high probability. In this paper, by investigating an optimization problem induced by the sufficient condition, we derive a condition such that it is optimal to use a constant batch size. This condition gives us a guideline for designing practical network protocol based on BATS codes. Moreover, we prove that this condition is always satisfied in line networks.
Autors: Qiaoqiao Zhou;Shenghao Yang;Hoover H. F. Yin;Bin Tang;
Appeared in: IEEE Communications Letters
Publication date: Sep 2017, volume: 21, issue:9, pages: 1917 - 1920
Publisher: IEEE
 
» On Country: Australian Aboriginal Communities, Mining, and Artificial Intelligence [Opinion]
Abstract:
Autors: Alexander Hayes;
Appeared in: IEEE Technology and Society Magazine
Publication date: Sep 2017, volume: 36, issue:3, pages: 37 - 40
Publisher: IEEE
 
» On Developing a Driver Identification Methodology Using In-Vehicle Data Recorders
Abstract:
Recently, cutting edge technologies to facilitate data collection have emerged on a large scale. One of the most prominent is the in-vehicle data recorder (IVDR). There are multiple ways to assign the IVDR’s data to the different drivers who share the same vehicle. Irrespective of the level of sophistication, all of these technologies still suffer considerable limitations in their accuracy. The purpose of this paper is to propose a methodology, which can identify the driver of a given trip using historical trip-based data. To do so, an advanced machine learning pipeline is proposed. The main goal is to take advantage of highly available data—such as driver-labeled floating car data collected by a IVDR—to build a pattern-based algorithm able to identify the trip’s driver category when its true identity is unknown. This stepwise process includes feature generation/selection, multiple heterogeneous explanatory models, and an ensemble approach (i.e., stacked generalization) to reduce their generalization error. Our goal is to provide an inexpensive alternative to existing driver identification technologies, which can serve as their complement and/or validation purposes. Experiments conducted over a real-world case study from Israel uncover the potential of this idea: it obtained an accuracy of ~88% and Cohen’s Kappa agreement score of ~74%.
Autors: Luis Moreira-Matias;Haneen Farah;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Sep 2017, volume: 18, issue:9, pages: 2387 - 2396
Publisher: IEEE
 
» On Distinguishing of Non-Signaling Boxes via Completely Locality Preserving Operations
Abstract:
We introduce a scenario of discrimination between bipartite boxes and apply it to boxes with two binary inputs and two binary outputs (). We develop the analogy between the theory of Bell non-locality and the theory of entanglement by considering the class of completely locality preserving (CLP) operations. A CLP operation satisfies two conditions: 1) transforms boxes with local hidden variable model (LHVM) into boxes with LHVM (i.e., is locality preserving) and 2) when tensored with an identity operation, forms a new operation, which is also locality preserving. We derive linear program, which gives an upper bound on the probability of success of discrimination between different isotropic boxes using this class of operations. In particular, we provide an upper bound on the probability of success of discrimination between isotropic boxes with the same mixing parameter. As a counterpart of entanglement monotone, we use the non-locality cost. Discrimination is restricted by the fact that non-locality cost does not increase under considered class of operations and geometry of boxes. We provide an example of CLP operations, which are called comparing operations (COP). The latter operations consist of direct measurement of the shared box by both the parties, followed by a predefined strategy in order to establish the guess, which may depend on the obtained outcomes. We then show that with the help of the COP operations, one can distinguish perfectly any two extremal boxes in case and any local extremal box from any other extremal box in case of two inputs and two outputs of arbitrary cardinalities.
Autors: Karol Horodecki;
Appeared in: IEEE Transactions on Information Theory
Publication date: Sep 2017, volume: 63, issue:9, pages: 5666 - 5683
Publisher: IEEE
 
» On Divergence-Angle Efficiency of a Laser Beam in Free-Space Optical Communications for High-Speed Trains
Abstract:
We compare narrow and wide laser beams in a free-space optical (FSO) communications system for high-speed train communications and analyze the tradeoffs among the received power, coverage area, and the complexity of the acquisition-tracking-pointing (ATP) mechanism. We propose to employ a divergence angle of a wide beam in the range [0.07, 2.002] to relax the steering speed of the fast steering mirror, which is a major component of the ATP mechanism in an FSO transceiver. In addition, we overcome the negative effects of train vibrations by using a proposed divergence-angle range for a wide beam. The proposed range of divergence angles provides a large link range and effective coverage length, and contact time as compared to a narrow beam.
Autors: Yagiz Kaymak;Roberto Rojas-Cessa;Jianghua Feng;Nirwan Ansari;Mengchu Zhou;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Sep 2017, volume: 66, issue:9, pages: 7677 - 7687
Publisher: IEEE
 
» On Dynamic Service Function Chain Deployment and Readjustment
Abstract:
Network function virtualization (NFV) is a promising technology to decouple the network functions from dedicated hardware elements, leading to the significant cost reduction in network service provisioning. As more and more users are trying to access their services wherever and whenever, we expect the NFV-related service function chains (SFCs) to be dynamic and adaptive, i.e., they can be readjusted to adapt to the service requests’ dynamics for better user experience. In this paper, we study how to optimize SFC deployment and readjustment in the dynamic situation. Specifically, we try to jointly optimize the deployment of new users’ SFCs and the readjustment of in-service users’ SFCs while considering the trade-off between resource consumption and operational overhead. We first formulate an integer linear programming (ILP) model to solve the problem exactly. Then, to reduce the time complexity, we design a column generation (CG) model for the optimization. Simulation results show that the proposed CG-based algorithm can approximate the performance of the ILP and outperform an existing benchmark in terms of the profit from service provisioning.
Autors: Junjie Liu;Wei Lu;Fen Zhou;Ping Lu;Zuqing Zhu;
Appeared in: IEEE Transactions on Network and Service Management
Publication date: Sep 2017, volume: 14, issue:3, pages: 543 - 553
Publisher: IEEE
 
» On Efficient and Robust Anonymization for Privacy Protection on Massive Streaming Categorical Information
Abstract:
Protecting users’ privacy when transmitting a large amount of data over the Internet is becoming increasingly important nowadays. In this paper, we focus on the streaming categorical information and propose a novel anonymization technique for providing a strong privacy protection to safeguard against privacy disclosure and information tampering. Our technique utilizes an innovative two-phase anonymization approach which is very easy to implement, highly efficient in terms of speed and communication and is robust against possible tampering from adversaries. Extensive experimental evaluation that is conducted demonstrates that our technique is very efficient and more robust than the existing method.
Autors: Ji Zhang;Hongzhou Li;Xuemei Liu;Yonglong Luo;Fulong Chen;Hua Wang;Liang Chang;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Sep 2017, volume: 14, issue:5, pages: 507 - 520
Publisher: IEEE
 
» On Error Detection in Asymmetric Channels
Abstract:
We study the error detection problem in -ary asymmetric channels, wherein every input symbol is mapped to an output symbol satisfying . A general setting is assumed, where the noise vectors are (potentially) restricted in: 1) the amplitude, , 2) the Hamming weight, , and 3) the total weight, . Optimal codes detecting these types of errors are described for certain sets of parameters , both in the standard and in the cyclic () version of the problem. It is also demonstrated that these codes are optimal in the large alphabet limit for every and every block-length .
Autors: Mladen Kovačević;
Appeared in: IEEE Communications Letters
Publication date: Sep 2017, volume: 21, issue:9, pages: 1933 - 1936
Publisher: IEEE
 
» On Evaluation of Power Electronic Devices’ Efficiency for Nonsinusoidal Voltage Supply and Different Operating Powers
Abstract:
This paper analyses the impact of operating modes and nonideal power supply conditions on the efficiency of modern low-voltage power electronic devices. The sophisticated circuits and controls implemented in such devices are expected to result in increased efficiencies, higher operating power factors, and reduced harmonic emissions. However, the interactions of individual PE devices with the supplying network will impact exchanges of powers at fundamental system frequency and nonfundamental (i.e., harmonic) frequencies. This paper correlates the obtained results for harmonic performance and efficiencies over the entire range of operating powers of the considered PE devices using both standard definitions and some alternative interpretations.
Autors: Sasa Djokic;Roberto Langella;Jan Meyer;Robert Stiegler;Alfredo Testa;Xiao Xu;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Sep 2017, volume: 66, issue:9, pages: 2216 - 2224
Publisher: IEEE
 
» On Lyapunov-Metzler Inequalities and S-Procedure Characterizations for the Stabilization of Switched Linear Systems
Abstract:
In this note we present connections between two celebrated tools for the design of stabilising switching laws for continuous-time and discrete-time switched linear systems, namely Lyapunov-Metzler inequalities and S-procedure.
Autors: W. P. M. H. Heemels;A. Kundu;J. Daafouz;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Sep 2017, volume: 62, issue:9, pages: 4593 - 4597
Publisher: IEEE
 
» On Minimizing the Maximal Characteristic Frequency of a Linear Chain
Abstract:
We consider a linear chain of masses, each coupled to its two nearest neighbors by elastic springs. The maximal characteristic frequency of this dynamical system is a strictly convex function of certain parameters that depend on the masses and spring elasticities. Minimizing the maximal characteristic frequency under an affine constraint on these parameters is thus a convex optimization problem. For a homogeneous affine constraint, we prove that the mass and elasticity values that minimize the maximal characteristic frequency have a special structure: They are symmetric with respect to the middle of the chain and the optimal masses [spring elasticities] increase [decrease] toward the center of the chain. Intuitively speaking, this means that in order to minimize the maximal characteristic frequency we need to “fix” the center of the chain, by increasing [decreasing] the masses [spring elasticities] there. We further show that minimizing the maximal characteristic frequency of the linear chain is equivalent to maximizing the steady-state protein production rate in an important model from systems biology called the ribosome flow model.
Autors: Yoram Zarai;Michael Margaliot;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Sep 2017, volume: 62, issue:9, pages: 4827 - 4833
Publisher: IEEE
 
» On Network Footprint of Traffic Inspection and Filtering at Global Scrubbing Centers
Abstract:
Traffic diversion through powerful cloud-based scrubbing centers provides a solution for protecting against various DDoS attacks. In one respect, such a solution enables sanitizing attack traffic close to its source and saves precious resources for the network service provider. Contrarily, the diversion of the inspected traffic toward the scrubbing centers may increase its footprint in the network. The location of the scrubbing centers greatly affects the network resource utilization and, therefore, should be carefully considered in the design of the security service. In this paper, we investigate four deployment strategies and compare their performance on a network of Points-of-Presence and on several router level topologies obtained from the RocketFuel project. The deployment quality was measured using the following criteria: the footprint of the inspected traffic, the redistribution of load on the links, and the increase in communication latency. Our results show that the deployment strategy that is considered to perform well for locating network monitors by maximizing flow coverage results in the worst footprint when traffic diversion is employed. Overall, we show that the deployment strategy that is tailored for traffic filtering is also suitable for traffic monitoring, but not the other way around.
Autors: Polina Zilberman;Rami Puzis;Yuval Elovici;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Sep 2017, volume: 14, issue:5, pages: 521 - 534
Publisher: IEEE
 
» On Opportunistic mmWave Networks With Blockage
Abstract:
Migrating to higher frequencies using millimeter wave (mmWave) signaling will expand the networks capacity to satiate the current demand for higher throughput. However, the overhead cost required for a centralized scheduler to function in an mmWave network quickly becomes intractable as user and access point (AP) density increase. Alternatively, a decentralized approach where users in mmWave networks opportunistically transmit may greatly benefit from a higher AP density. Taking advantage of the AP diversity projected for mmWave networks a user may sequentially probe APs before selecting a destination AP for transmission. An opportunistic user in an mmWave network must balance the benefit of AP diversity against the overhead cost. We present an mmWave opportunistic network model encompassing the probability of an AP becoming unavailable and the cost of initial access. Our optimal opportunistic strategy is a set of thresholds, which are computable a priori. Bounds on average overhead, delay and throughput of our strategy are also presented. Via numerical analysis, we show that at finite and relatively small probings our proposed strategy outperforms practical alternatives.
Autors: David Ramirez;Lei Huang;Yi Wang;Behnaam Aazhang;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: Sep 2017, volume: 35, issue:9, pages: 2137 - 2147
Publisher: IEEE
 
» On Outage of WPC System With Relay Selection Over Nakagami- $m$ Fading Channels
Abstract:
This paper considers a dual-hop wireless powered cooperative system with multiple relays, which consists of a source (S), a destination (D), and multiple relay candidates. These relay candidates can harvest energy from the interference signals to transfer the decoded data to D. Two classic relay selection schemes, i.e., the optimal source-relay link (OSRL) and optimal source-relay-destination link (OSRDL) schemes, are considered to choose a best relay to aid the transmission between S and D under the conditional decode-and-forward (DF) scheme. The closed-form expressions of the outage probability for the two considered relay selection schemes have been derived and verified over independent Nakagami- fading channels.
Autors: Han Yu;Danyang Wang;Gaofeng Pan;Rui Shi;Jiliang Zhang;Yunfei Chen;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Sep 2017, volume: 66, issue:9, pages: 8590 - 8594
Publisher: IEEE
 
» On Quadratic Permutation Polynomials, Turbo Codes, and Butterfly Networks
Abstract:
The use of quadratic permutation polynomials as interleavers for turbo codes is justified, among other things, by the fact that the quadratic permutation polynomials provide turbo codes of very good performance and simultaneously they support a specific conflict-free parallel access to extrinsic values in two different access orders. It is rather easy to write and read in parallel to and from multiple memories by one access order. Nevertheless, turbo decoders have to access the multiple memories at least by two different access orders. Then, parallel writes and reads lead to conflicts in accessing the multiple memories. Having only one conflict-free parallel access method for quadratic permutation polynomials restricts to design efficient flexible (multistandard) decoders for turbo codes at high data rates. We show that quadratic permutation polynomials with butterfly networks as interconnection networks between decoder units and memories support many kinds of flexible and variant conflict-free parallel access methods for turbo codes that are not known today. This result extends possibilities to implement high speed turbo decoders not only by application specific circuits but also by (general purpose) graphics processor units for (multistandard) modems.
Autors: Esko Nieminen;
Appeared in: IEEE Transactions on Information Theory
Publication date: Sep 2017, volume: 63, issue:9, pages: 5793 - 5801
Publisher: IEEE
 
» On Relay Selection Schemes for Relay-Assisted D2D Communications in LTE-A Systems
Abstract:
Device-to-device (D2D) communication is a promising technique for traffic offloading in next-generation cellular systems. However, the use of only direct D2D communications limits the advantages of D2D communications due to relatively long separation distances or poor link quality between source and destination user equipments (UEs). Relay-assisted D2D communication was proposed as a supplement to direct D2D communications for enhancing traffic offloading capacity in long-term evolution–advanced (LTE-A) systems. This work aims to design a relay UE selection strategy for D2D communications, which improves D2D communication performance significantly. We propose a cross-layer relay selection scheme that considers several criteria jointly, including end-to-end data rate, relay-capable UE (RUE) remaining battery time, and end-to-end transmission delay on relay-assisted D2D path. We show how to leverage these criteria at an eNB performing relay selection in D2D communications. In particular, an end-to-end delay estimation model is established based on queuing theory. Simulation results validate the performance of the proposed scheme in terms of total amount of data transmitted under RUE remaining battery and end-to-end transmission delay.
Autors: Ruofei Ma;Yao-Jen Chang;Hsiao-Hwa Chen;Chun-Yuan Chiu;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Sep 2017, volume: 66, issue:9, pages: 8303 - 8314
Publisher: IEEE
 
» On Secondary Control Approaches for Voltage Regulation in DC Microgrids
Abstract:
Centralized or decentralized secondary controller is commonly employed to regulate the voltage drop raised by the primary controller. However, in the case of high capacity microgrids (MGs) and long feeders with much voltage drop on the line resistances, the conventional methods may not guarantee the voltage regulation on the load busses within a suitable range. Therefore, in addition to compensate the voltage drop of the primary controller, it is necessary to regulate the voltage of critical loads. In this paper, a new voltage regulation strategy is proposed to regulate the voltage of MG by employing the average voltage of identified critical busses, which are determined by the proposed modal analysis. Numerical steady-state analysis and preliminary simulation results validate effectiveness of the proposed scheme. Furthermore, experimental results are performed to demonstrate the viability of the proposed approach.
Autors: Saeed Peyghami;Hossein Mokhtari;Pooya Davari;Poh Chiang Loh;Frede Blaabjerg;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Sep 2017, volume: 53, issue:5, pages: 4855 - 4862
Publisher: IEEE
 
» On the Achievable Spectral Efficiency of Spatial Modulation Aided Downlink Non-Orthogonal Multiple Access
Abstract:
In this letter, a novel spatial modulation aided non-orthogonal multiple access (SM-NOMA) system is proposed. We use mutual information (MI) to characterize the achievable spectral efficiency (SE) of the proposed SM-NOMA system. Due to the finite-alphabet space-domain inputs employed by SM, the expression of the corresponding MI lacks a closed-form formulation. Hence, a lower bound is proposed to quantify the MI of the SM-NOMA system. Furthermore, its asymptotic property is also theoretically investigated in both low and high signal-to-noise ratio regions. The SE performance and its analysis of our proposed SM-NOMA system are confirmed by simulation results.
Autors: Xuesi Wang;Jintao Wang;Longzhuang He;Zihan Tang;Jian Song;
Appeared in: IEEE Communications Letters
Publication date: Sep 2017, volume: 21, issue:9, pages: 1937 - 1940
Publisher: IEEE
 
» On the Adaptation of Pelvic Motion by Applying 3-dimensional Guidance Forces Using TPAD
Abstract:
Pelvic movement is important to human locomotion as the center of mass is located near the center of pelvis. Lateral pelvic motion plays a crucial role to shift the center of mass on the stance leg, while swinging the other leg and keeping the body balanced. In addition, vertical pelvic movement helps to reduce metabolic energy expenditure by exchanging potential and kinetic energy during the gait cycle. However, patient groups with cerebral palsy or stroke have excessive pelvic motion that leads to high energy expenditure. In addition, they have higher chances of falls as the center ofmass could deviate outside the base of support. In this paper, a novel control method is suggested using tethered pelvic assist device (TPAD) to teach subjects to walk with a specified target pelvic trajectory while walking on a treadmill. In this method, a force field is applied to the pelvis to guide it to move on a target trajectory and correctional forces are applied, if the pelvis motion has excessive deviations from the target trajectory. Three different experimentswith healthy subjects were conducted to teach them to walk on a new target pelvic trajectory with the presented control method. For all three experiments, the baseline trajectory of the pelvis was experimentally determined for each participating subject. To design a target pelvic trajectory which is different from the baseline, Experiment I scaled up the lateral component of the baseline pelvic trajectory, while Experiment II scaled down the lateral component of the baseline trajectory. For both Experiments I and II, the controller generated a 2-D force field in the transverse plane to provide the guidance force. In this paper, seven subjects were recruited for each experiment who walked on the treadmill with suggested control methods and visual feedback of their pelvic trajectory. The results show that the subjects were able to learn the target pelvic trajectory in each experiment and also retained the training effe- ts after the completion of the experiment. In Experiment III, both lateral and vertical components of the pelvic trajectory were scaled down from the baseline trajectory. The force field was extended to three dimensions in order to correct the vertical pelvic movement as well. Three subgroups (force feedback alone, visual feedback alone, and both force and visual feedback) were recruited to understand the effects of force feedback and visual feedback alone to distinguish the results from Experiments I and II. The results showthat a trainingmethod that combines visual and force feedback is superior to the training methods with visual or force feedback alone. We believe that the present control strategy holds potential in training and correcting abnormal pelvic movements in different patient populations.
Autors: Jiyeon Kang;Vineet Vashista;Sunil K. Agrawal;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Sep 2017, volume: 25, issue:9, pages: 1558 - 1567
Publisher: IEEE
 
» On the Aloha Throughput-Fairness Tradeoff
Abstract:
A well-known inner bound of the stability region of the finite-user slotted Aloha protocol (with fixed contention probabilities) on the collision channel with users assumes worst case service rates (all user queues non-empty). Using this inner bound as a feasible set of achievable rates, a characterization of the throughput–fairness tradeoff over this set is obtained, where the throughput is defined as the sum of the individual user rates, and two definitions of fairness are considered: the Jain–Chiu–Hawe function and the sum-user -fair (isoelastic) utility function. This characterization is obtained using both an equality constraint and an inequality constraint on the throughput, and properties of the optimal controls, the optimal rates, and the maximum fairness as a function of the target throughput are established. A key structural property underpinning all theorems is the observation that the vector of contention probabilities that extremizes both fairness objectives has its nonzero components taking at most two distinct values.
Autors: Nan Xie;Steven Weber;
Appeared in: IEEE Transactions on Information Theory
Publication date: Sep 2017, volume: 63, issue:9, pages: 6085 - 6112
Publisher: IEEE
 
» On the Buffer Energy Aware Adaptive Relaying in Multiple Relay Network
Abstract:
In this paper, we study a buffer-aided collaborative relaying framework for cooperative communication system composed of one source node, multiple half-duplex DF relays with buffers, and one destination node. A two-phase adaptive relaying scheme is proposed, i.e., the source transmits data and the relay buffers receive data in the first phase, and all relays collaboratively transmit the buffered data to the destination node in the second phase. To achieve higher temporal and spatial diversity gains, time slots are dynamically allocated according to the state information of wireless channel (CSI), each node’s energy consumption (ESI), and each relay’s buffer (BSI). Lyapunov optimization theory is utilized to maximize the average achievable throughput under buffer stability and power consumption constraints, and an online buffer-energy-aware adaptive (BEAA) scheduling scheme is proposed to jointly consider relay selection, power allocation, and time allocation. It is disclosed that the proposed BEAA scheduling scheme is able to achieve a higher average network throughput by adapting the transmissions according to the CSI, ESI, and BSI. Moreover, it is unveiled that there exists inherent tradeoff among the transmission delay, power consumption, and the achievable throughput. Extensive simulations are presented to validate the efficiency of the proposed adaptive collaborative relaying protocol.
Autors: Yong Liu;Qingchun Chen;Xiaohu Tang;Lin X. Cai;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Sep 2017, volume: 16, issue:9, pages: 6248 - 6263
Publisher: IEEE
 
» On the Capacity of the Carbon Copy onto Dirty Paper Channel
Abstract:
The “carbon copy onto dirty paper” (CCDP) channel is the compound “writing on dirty paper” channel in which the channel output is obtained as the sum of the channel input, white Gaussian noise and a Gaussian state sequence randomly selected among a set possible realizations. The transmitter has non-causal knowledge of the set of possible state sequences but does not know which sequence is selected to produce the channel output. We study the capacity of the CCDP channel for two scenarios: 1) the state sequences are independent and identically distributed; and 2) the state sequences are scaled versions of the same sequence. In the first scenario, we show that a combination of superposition coding, time-sharing, and Gel’fand-Pinsker binning is sufficient to approach the capacity to within 3 bits per channel use for any number of possible state realizations. In the second scenario, we derive capacity to within 4 bits per channel use for the case of two possible state sequences. This result is extended to the CCDP channel with any number of possible state sequences under certain conditions on the scaling parameters, which we denote as “strong fading” regime. We conclude by providing some remarks on the capacity of the CCDP channel in which the state sequences have any jointly Gaussian distribution.
Autors: Stefano Rini;Shlomo Shamai Shitz;
Appeared in: IEEE Transactions on Information Theory
Publication date: Sep 2017, volume: 63, issue:9, pages: 5907 - 5922
Publisher: IEEE
 
» On the Convergence of a Distributed Augmented Lagrangian Method for Nonconvex Optimization
Abstract:
In this paper, we propose a distributed algorithm for optimization problems that involve a separable, possibly nonconvex objective function subject to convex local constraints and linear coupling constraints. The method is based on the accelerated distributed augmented Lagrangians (ADAL) algorithm that was recently developed by the authors to address convex problems. Here, we extend this line of work in two ways. First, we establish convergence of the method to a local minimum of the problem, using assumptions that are common in the analysis of nonconvex optimization methods. To the best of our knowledge, this is the first work that shows convergence to local minima specifically for a distributed augmented Lagrangian (AL) method applied to nonconvex optimization problems; distributed AL methods are known to perform very well when used to solve convex problems. Second, we propose a more general and decentralized rule to select the stepsizes of the method. This improves on the authors’ original ADAL method, where the stepsize selection used global information at initialization. Numerical results are included to verify the correctness and efficiency of the proposed distributed method.
Autors: Nikolaos Chatzipanagiotis;Michael M. Zavlanos;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Sep 2017, volume: 62, issue:9, pages: 4405 - 4420
Publisher: IEEE
 
» On the coverage of multiple-input multiple-output visible light communications [Invited]
Abstract:
Visible light communication (VLC) using multiple-input multiple-output (MIMO) has great potential for future high-data-rate indoor wireless communications. Owing to the dual function of white light-emitting diodes (LEDs), i.e., illumination and communication functions, both the illumination and communication coverages need to be evaluated when implementing an indoor MIMO-VLC system. In this paper, we present a comprehensive investigation of both the illumination and communication coverages of an indoor MIMO-VLC system. Two techniques are applied in the MIMO-VLC system for communication coverage improvement, including a non-Hermitian symmetry orthogonal frequency division multiplexing (NHS-OFDM) modulation scheme and an imaging angle diversity receiver. A general indoor imaging MIMO-VLC system using NHS-OFDM is described and the analytical bit error rate expression of the system is derived. The impact of LED pairing on the communication coverage of an indoor imaging MIMO-VLC system based on NHS-OFDM is also analyzed.
Autors: Chen Chen;Wen-De Zhong;Dehao Wu;
Appeared in: IEEE/OSA Journal of Optical Communications and Networking
Publication date: Sep 2017, volume: 9, issue:9, pages: D31 - D41
Publisher: IEEE
 
» On the Degrees of Freedom of the Symmetric Multi-Relay MIMO Y Channel
Abstract:
In this paper, we study the degrees of freedom (DoF) of the symmetric multi-relay multiple-input multiple-output Y channel, where three user nodes, each with antennas, communicate via geographically separated relay nodes, each with antennas. For this model, we establish a general DoF achievability framework based on linear precoding and post-processing methods. The framework poses a nonlinear problem with respect to user precoders, user post-processors, and relay precoders. To solve this problem, we adopt an uplink–downlink asymmetric strategy, where the user precoders are designed for signal alignment and the user post-processors are used for interference neutralization. With the user precoder and post-processor designs fixed as such, the original problem then reduces to a problem of relay precoder design. To address the solvability of the system, we propose a general method for solving matrix equations. Together with the techniques of antenna disablement and symbol extension, an achievable DoF of the considered model is derived for an arbitrary setup of . We show that for , the optimal DoF is achieved for . We also show that the uplink-downlink asymmetric design proposed in this paper considerably outperforms the conventional approach based on uplink-downlink symmetry.
Autors: Tian Ding;Xiaojun Yuan;Soung Chang Liew;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Sep 2017, volume: 16, issue:9, pages: 5673 - 5688
Publisher: IEEE
 
» On the Effects of a Routing and Reservation System on the Electric Vehicle Public Charging Network
Abstract:
One solution to the limited range of battery electric vehicles is the provision of a public charging infrastructure to enable longer journeys. This paper describes a simulation model of a routing and charge point reservation system based on the charging infrastructure deployed in Ireland during early 2016. Extensive Monte Carlo simulations are run using the Irish population density and an estimated trip length distribution. The results show quantitatively the advantages of a routing and charge point reservation systems on a country wide scale in terms of the number of electric vehicles that can be supported. The effect of charge point fault rates is also quantitatively assessed and shown to be a critical factor in public charging infrastructure deployment.
Autors: Thomas Conway;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Sep 2017, volume: 18, issue:9, pages: 2311 - 2318
Publisher: IEEE
 
» On the Energy-Efficiency of Hybrid Analog–Digital Transceivers for Single- and Multi-Carrier Large Antenna Array Systems
Abstract:
Hybrid analog-digital transceivers are employed with the view to reduce the hardware complexity and the energy consumption in millimeter wave/large antenna array systems by reducing the number of their radio frequency (RF) chains. However, the analog processing network requires power for its operation and it further introduces power losses, dependent on the number of the transceiver antennas and RF chains that have to be compensated. Thus, the reduction in the power consumption is usually much less than it is expected and given that the hybrid solutions present in general inferior spectral efficiency than a fully digital one, it is possible for the former to be less energy efficient than the latter in several cases. Existing approaches propose hybrid solutions that maximize the spectral efficiency of the system without providing any insight on their energy requirements/efficiency. To that end, in this paper, a novel algorithmic framework is developed based on which energy efficient hybrid transceiver designs are derived and their performance is examined with respect to the number of RF chains and antennas. Solutions are proposed for fully and partially connected hybrid architectures and for both single- and multi-carrier systems under the orthogonal frequency division multiplexing modulation. Simulations and theoretical results provide insight on the cases, where a hybrid transceiver is the most energy efficient solution or not.
Autors: Christos G. Tsinos;Sina Maleki;Symeon Chatzinotas;Björn Ottersten;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: Sep 2017, volume: 35, issue:9, pages: 1980 - 1995
Publisher: IEEE
 
» On the Graph Fourier Transform for Directed Graphs
Abstract:
The analysis of signals defined over a graph is relevant in many applications, such as social and economic networks, big data or biological networks, and so on. A key tool for analyzing these signals is the so-called graph Fourier transform (GFT). Alternative definitions of GFT have been suggested in the literature, based on the eigen-decomposition of either the graph Laplacian or adjacency matrix. In this paper, we address the general case of directed graphs and we propose an alternative approach that builds the graph Fourier basis as the set of orthonormal vectors that minimize a continuous extension of the graph cut size, known as the Lovász extension. To cope with the nonconvexity of the problem, we propose two alternative iterative optimization methods, properly devised for handling orthogonality constraints. Finally, we extend the method to minimize a continuous relaxation of the balanced cut size. The formulated problem is again nonconvex, and we propose an efficient solution method based on an explicit–implicit gradient algorithm.
Autors: Stefania Sardellitti;Sergio Barbarossa;Paolo Di Lorenzo;
Appeared in: IEEE Journal of Selected Topics in Signal Processing
Publication date: Sep 2017, volume: 11, issue:6, pages: 796 - 811
Publisher: IEEE
 
» On The Modeling and Analysis of Uplink and Downlink IEEE 802.11ax Wi-Fi With LTE in Unlicensed Spectrum
Abstract:
The growing demand on data to enhance the user experience has motivated research toward increasing the efficiency of spectrum utilization by extending cellular technology, such as LTE, toward unlicensed bands. In order to study the fair coexistence of LTE and Wi-Fi, we consider the IEEE 802.11ax Wi-Fi standard, where we use stochastic geometry to model and analyze the coexistence of LTE with simultaneous uplink and downlink IEEE 802.11ax transmissions. Mainly, we consider LTE with continuous transmissions (no protocol change), LTE with discontinuous transmissions (LTE-U), and licensed-assisted access (LAA) coexistence mechanisms. In addition, we focus on single unlicensed frequency band transmissions, where the locations of Wi-Fi access points, Wi-Fi stations (users), and LTE eNodeBs (eNBs) are modeled as three independent homogeneous Poisson point processes. Then, we derive analytical expressions for a set of performance metrics, which are the medium access probability, signal-to-interference-plus-noise ratio coverage probability, density of successful transmissions, and Shannon throughput probability for both uplink and downlink of IEEE 802.11ax in addition to LTE. Our analysis quantifies both single-user and multi-user operation modes of the IEEE802.11ax and show that LTE-U or LAA can be a good neighbor for IEEE 802.11ax for different traffic types.
Autors: Abdel-karim Ajami;Hassan Artail;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Sep 2017, volume: 16, issue:9, pages: 5779 - 5795
Publisher: IEEE
 
» On the Modeling and Compensation of Backward Crosstalk in MIMO Transmitters
Abstract:
In this letter, the impact of backward crosstalk at the output of power amplifiers (PAs) on the behavioral model of the multi-input multi-output (MIMO) transmitter is investigated. In this case, the interference signal from other branches leaks into the output of PA and changes the PA behavioral model. A novel generalized memory polynomial is proposed to model the nonlinear distortion caused by this type of crosstalk. Moreover, it is shown that a digital predistortion (DPD) algorithm based on a 2-D generalized memory polynomial can efficiently compensate for the nonlinearity and backward crosstalk impairment effects in MIMO transmitter. The experimental results validate the performance of the proposed model and the DPD method in four different scenarios. An adjusted channel power ratio of less than −50 dBc for the linearized output signal in the presence of −15/−10 dB crosstalk is achieved.
Autors: Amir Vaezi;Abdolali Abdipour;Abbas Mohammadi;Fadhel M. Ghannouchi;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Sep 2017, volume: 27, issue:9, pages: 842 - 844
Publisher: IEEE
 
» On the Performance of MIMO-SVD Multiplexing Systems in HetNets: A Stochastic Geometry Perspective
Abstract:
In the paper, we study network-wise performance of multistream multi-input multi-output (MIMO) singular value decomposition communications in heterogeneous networks (HetNets). We adopt tools from stochastic geometry to model HetNets through tiers of interfering base stations (BSs) and evaluate the coverage probability and achievable spectral efficiency (ASE), assuming max-signal-to-interference ratio (SIR) cell association rule. For this model, the main contributions are 1) studying the coverage probability of MIMO multiplexing systems from a communication link's viewpoint; 2) investigating the cross-stream SIR correlation coefficient and highlighting the impacts of path-loss exponent and the number of receive antennas on the growth of it; and 3) obtaining easy-to-compute closed-form approximates of the coverage probability and ASE. The developed expressions explicitly reveal the impact of many system parameters, including the number of tiers, density of BSs, transmission power, and the number of data streams. Simulations are conducted to confirm the accuracy of our analysis. Various important aspects of HetNets with respect to densification, high multiplexing gains, and large antenna arrays are demonstrated. Results showcase the significance of channel state information at the transmitter on the network's performance. With the results of this paper, further investigations and system designs are made possible.
Autors: Mohammad G. Khoshkholgh;Victor C. M. Leung;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Sep 2017, volume: 66, issue:9, pages: 8163 - 8178
Publisher: IEEE
 
» On the Physical Behavior of Cryogenic IV and III–V Schottky Barrier MOSFET Devices
Abstract:
The physical influence of temperature down to the cryogenic regime is analyzed in a comprehensive study and the comparison of IV and III–V Schottky barrier (SB) double-gate MOSFETs. The exploration is done using the Synopsys TCAD Sentaurus device simulator and first benchmarked with experimental data. The important device physics of both SB-MOSFETs and conventional MOSFETs are reviewed. The impact of temperature on device performance down to the liquid-nitrogen regime is then explored. We find reduced drive currents in SB-MOSFETs fabricated on small effective mass materials and that SB lowering can significantly improve SB-MOSFETs, especially at low temperatures.
Autors: Mike Schwarz;Laurie E. Calvet;John P. Snyder;Tillmann Krauss;Udo Schwalke;Alexander Kloes;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Sep 2017, volume: 64, issue:9, pages: 3808 - 3815
Publisher: IEEE
 
» On the Placement Delivery Array Design for Centralized Coded Caching Scheme
Abstract:
Caching is a promising solution to satisfy the ever-increasing demands for the multi-media traffics. In caching networks, coded caching is a recently proposed technique that achieves significant performance gains over the uncoded caching schemes. However, to implement the coded caching schemes, each file has to be split into packets, which usually increases exponentially with the number of users . Thus, designing caching schemes that decrease the order of is meaningful for practical implementations. In this paper, by reviewing the Ali-Niesen caching scheme, the placement delivery array (PDA) design problem is first formulated to characterize the placement issue and the delivery issue with a single array. Moreover, we show that, through designing appropriate PDA, new centralized coded caching schemes can be discovered. Second, it is shown that the Ali-Niesen scheme corresponds to a special class of PDA, which realizes the best coding gain with the least . Third, we present a new construction of PDA for the centralized coded caching system, wherein the cache size at each user (identical cache size is assumed at all users) and the number of files satisfies or ( is an integer, such that ). The n- w construction can decrease the required from the order of Ali-Niesen scheme to or , respectively, while the coding gain loss is only 1.
Autors: Qifa Yan;Minquan Cheng;Xiaohu Tang;Qingchun Chen;
Appeared in: IEEE Transactions on Information Theory
Publication date: Sep 2017, volume: 63, issue:9, pages: 5821 - 5833
Publisher: IEEE
 
» On the Relation Between the Minimum Principle and Dynamic Programming for Classical and Hybrid Control Systems
Abstract:
Hybrid optimal control problems are studied for a general class of hybrid systems, where autonomous and controlled state jumps are allowed at the switching instants, and in addition to terminal and running costs, switching between discrete states incurs costs. The statements of the Hybrid Minimum Principle and Hybrid Dynamic Programming are presented in this framework, and it is shown that under certain assumptions, the adjoint process in the Hybrid Minimum Principle and the gradient of the value function in Hybrid Dynamic Programming are governed by the same set of differential equations and have the same boundary conditions and hence are almost everywhere identical to each other along optimal trajectories. Analytic examples are provided to illustrate the results.
Autors: Ali Pakniyat;Peter E. Caines;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Sep 2017, volume: 62, issue:9, pages: 4347 - 4362
Publisher: IEEE
 
» On the SEP Analysis of OFDM Index Modulation With Hybrid Low Complexity Greedy Detection and Diversity Reception
Abstract:
In this work, we investigate the performance of multicarrier index keying (MCIK) orthogonal frequency division multiplexing (OFDM) proposing a hybrid low complexity detection and diversity reception. For performance analysis, we derive novel exact closed-form expressions for the average pairwise error probability (PEP) and symbol error probability (SEP) of three detection methods: a greedy detector (GD), and a GD with maximal ratio combining, or selection combining. Approximate and accurate expressions for the average PEP and SEP are also analyzed in closed-form. The derived expressions provide a useful insight into the error performance of MCIK-OFDM with the hybrid detector in low, moderate, and extreme rate of sparse sub-carrier indices activation. The effects of multiple antennas and sparse sub-carriers activation on the SEP are addressed in several extreme cases; decreasing the average SEP exponentially with proper choice of both subcarrier activation rate and number of antennas. In comparison with the benchmark detection, the numerical results and simulations clearly show that the proposed schemes can benefit from diversity gain, at substantially reduced complexity. The derived SEP expressions and analyses will be useful to evaluate various concepts of MCIK OFDM in low-power device applications.
Autors: James Crawford;Eleftherios Chatziantoniou;Youngwook Ko;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Sep 2017, volume: 66, issue:9, pages: 8103 - 8118
Publisher: IEEE
 
» On the Separation of Ground and Volume Scattering Using Multibaseline SAR Data
Abstract:
In forest and agricultural scattering scenarios, the backscattered synthetic aperture radar (SAR) signature consists, depending on the frequency, of the superposition of ground and volume scattering contributions. Using multibaseline SAR data, SAR tomography techniques allow resolving contributions occurring at different heights. Two algorithms for the separation of ground and volume scattering are compared with respect to their ability to provide a coherent volume component that can be further used for parameter inversion, both of them requiring only the a priori known ground topography. Once the volume-only coherences are available, the total ground and volume scattering powers are estimated by means of a least squares fitting. The objective of this letter is to quantitatively evaluate the performance of this estimation by means of a Monte Carlo analysis with simulated data focusing on the impact of vertical resolution, errors in the knowledge of the ground topography and phase calibration residuals.
Autors: Hannah Joerg;Matteo Pardini;Irena Hajnsek;Konstantinos P. Papathanassiou;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Sep 2017, volume: 14, issue:9, pages: 1570 - 1574
Publisher: IEEE
 
» On the Use of Eigenvector Centrality for Cooperative Streaming
Abstract:
The timely and efficient cooperative distribution of a streamlined content in a communication network is a key feature for many applications and services. One of the unsolved problems is the assignment of transmission rates to nodes, given the constraints imposed by the topology, so that all nodes receive the stream with the minimal global use of resources. This letter addresses the problem exploiting the notion of eigenvector centrality. It shows that the problem can be solved efficiently in a distributed way if every node is aware of the full network topology and that in certain cases only local information on the network graph is sufficient.
Autors: Luca Baldesi;Leonardo Maccari;Renato Lo Cigno;
Appeared in: IEEE Communications Letters
Publication date: Sep 2017, volume: 21, issue:9, pages: 1953 - 1956
Publisher: IEEE
 
» On User Association in Multi-Tier Full-Duplex Cellular Networks
Abstract:
We address the user association problem in multi-tier in-band full-duplex (FD) networks. Specifically, we consider the case of decoupled user association (DUA), in which users (UEs) are not necessarily served by the same base station (BS) for uplink (UL) and downlink (DL) transmissions. Instead, UEs can simultaneously associate to different BSs based on two independent weighted path-loss user association criteria for UL and DL. We use stochastic geometry to develop a comprehensive modeling framework for the proposed system model, where BSs and UEs are spatially distributed according to independent point processes. We derive closed-form expressions for the mean rate utility in FD, half-duplex (HD) DL, and HD UL networks as well as the mean rate utility of legacy nodes with only HD capabilities in a multi-tier FD network. We formulate and solve an optimization problem that aims at maximizing the mean rate utility of the FD network by optimizing the DL and UL user association criteria. We investigate the effects of different network parameters, including the spatial density of BSs and power control parameter. We also investigate the effect of imperfect self-interference cancellation (SIC) and show that it is more severe at UL, where there exist minimum required SIC capabilities for BSs and UEs, for which FD networks are preferable to HD networks; otherwise, HD networks are preferable. In addition, we discuss several special cases and provide guidelines on the possible extensions of the proposed framework. We conclude that DUA outperforms coupled user association, in which UEs associate to the same BS for both UL and DL transmissions.
Autors: Ahmed Hamdi Sakr;Ekram Hossain;
Appeared in: IEEE Transactions on Communications
Publication date: Sep 2017, volume: 65, issue:9, pages: 4080 - 4095
Publisher: IEEE
 
» Online Map-Matching of Noisy and Sparse Location Data With Hidden Markov and Route Choice Models
Abstract:
With the growing use of crowdsourced location data from smartphones for transportation applications, the task of map-matching raw location sequence data to travel paths in the road network becomes more important. High-frequency sampling of smartphone locations using accurate but power-hungry positioning technologies is not practically feasible as it consumes an undue amount of the smartphone’s bandwidth and battery power. Hence, there exists a need to develop robust algorithms for map-matching inaccurate and sparse location data in an accurate and timely manner. This paper addresses the above-mentioned need by presenting a novel map-matching solution that combines the widely used approach based on a hidden Markov model (HMM) with the concept of drivers’ route choice. Our algorithm uses an HMM tailored for noisy and sparse data to generate partial map-matched paths in an online manner. We use a route choice model, estimated from real drive data, to reassess each HMM-generated partial path along with a set of feasible alternative paths. We evaluated the proposed algorithm with real world as well as synthetic location data under varying levels of measurement noise and temporal sparsity. The results show that the map-matching accuracy of our algorithm is significantly higher than that of the state of the art, especially at high levels of noise.
Autors: George R. Jagadeesh;Thambipillai Srikanthan;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Sep 2017, volume: 18, issue:9, pages: 2423 - 2434
Publisher: IEEE
 
» Online Parametric Identification of Power Impedances to Improve Stability and Accuracy of Power Hardware-in-the-Loop Simulations
Abstract:
This paper presents the wideband system identification (WSI) technique, i.e., an online method to identify power impedances over a wide frequency range from which the corresponding parametric impedance can be calculated online as well. The WSI technique exploits an existing custom 25-kW power electronic converter on the top of its power conversion function, which serves as power amplifier of an existing power hardware-in-the-loop (PHiL) simulation setup. The PHiL simulation technique allows connecting a real device under test (DUT) with the real-time simulated rest of system (ROS) at power level. An interface algorithm (IA) on simulation side and a power amplifier (the 25-kW power electronic converter) connect ROS and DUT. This paper shows the impact of the uncertainties in the WSI chain on the accuracy of the impedance identification and highlights how the WSI technique can be combined with the damping impedance method IA to improve both accuracy and stability of the PHiL test bench. The application of the method is illustrated for the scenario of a PHiL test of a dc microgrid with a passive load.
Autors: Antonino Riccobono;Eyke Liegmann;Marco Pau;Ferdinanda Ponci;Antonello Monti;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Sep 2017, volume: 66, issue:9, pages: 2247 - 2257
Publisher: IEEE
 
» Open Challenges for Probabilistic Measurement-Based Worst-Case Execution Time
Abstract:
The worst-case execution time (WCET) is a critical parameter describing the largest value for the execution time of programs. Even though such a parameter is very hard to attain, it is essential as part of guaranteeing a real-time system meets its timing requirements. The complexity of modern hardware has increased the challenges of statically analyzing the WCET and reduced the reliability of purely measuring the WCET. This has led to the emergence of probabilistic WCETs (pWCETs) analysis as a viable technique. The low probability of appearance of large execution times of a program has motivated the utilization of rare events theory like extreme value theory (EVT). As pWCET estimation based on EVT has matured as a discipline, a number of open challenges have become apparent when applying the existing approaches. This letter enumerates key challenges while establishing a state of the art of EVT-based pWCET estimation methods.
Autors: Samuel Jiménez Gil;Iain Bate;George Lima;Luca Santinelli;Adriana Gogonel;Liliana Cucu-Grosjean;
Appeared in: IEEE Embedded Systems Letters
Publication date: Sep 2017, volume: 9, issue:3, pages: 69 - 72
Publisher: IEEE
 
» Operational Implementation of Sea Ice Concentration Estimates From the AMSR2 Sensor
Abstract:
An operation implementation of a passive microwave sea ice concentration algorithm to support NOAA's operational mission is presented. The NASA team 2 algorithm, previously developed for the NASA advanced microwave scanning radiometer for the Earth observing system (AMSR-E) product suite, is adapted for operational use with the JAXA AMSR2 sensor through several enhancements. First, the algorithm is modified to process individual swaths and provide concentration from the most recent swaths instead of a 24-hour average. A latency (time since observation) field and a 24-hour concentration range (maximum–minimum) are included to provide indications of data timeliness and variability. Concentration from the Bootstrap algorithm is a secondary field to provide complementary sea ice information. A quality flag is implemented to provide information on interpolation, filtering, and other quality control steps. The AMSR2 concentration fields are compared with a different AMSR2 passive microwave product, and then validated via comparison with sea ice concentration from the Suomi visible and infrared imaging radiometer suite. This validation indicates the AMSR2 concentrations have a bias of 3.9% and an RMSE of 11.0% in the Arctic, and a bias of 4.45% and RMSE of 8.8% in the Antarctic. In most cases, the NOAA operational requirements for accuracy are met. However, in low-concentration regimes, such as during melt and near the ice edge, errors are higher because of the limitations of passive microwave sensors and the algorithm retrieval.
Autors: Walter N. Meier;J. Scott Stewart;Yinghui Liu;Jeffrey Key;Jeffrey A. Miller;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Sep 2017, volume: 10, issue:9, pages: 3904 - 3911
Publisher: IEEE
 
» Operationalizing SSIT?s 5 Pillars: Pillar 2: Ethics, Human Values and Technology [President's Message]
Abstract:
Autors: Paul Cunningham;
Appeared in: IEEE Technology and Society Magazine
Publication date: Sep 2017, volume: 36, issue:3, pages: 5 - 9
Publisher: IEEE
 
» OPF Techniques for Real-Time Active Management of Distribution Networks
Abstract:
This paper presents a method for real-time active network management (ANM) control to maximize network-wide energy yield in constrained networks. Coordinated scheduling of renewable distributed generation (DG) and distribution network control assets can limit DG curtailment and significantly increase energy yield and economic performance of DG. Here, an optimal power flow approach has been developed for real-time online scheduling of network control settings to better integrate high levels of temporally and spatially variable DG from renewable energy resources. Results show that the real-time prescription of ANM control settings provides a feasible alternative to network reinforcement under the existing passive management philosophy.
Autors: James G. Robertson;Gareth P. Harrison;A. Robin Wallace;
Appeared in: IEEE Transactions on Power Systems
Publication date: Sep 2017, volume: 32, issue:5, pages: 3529 - 3537
Publisher: IEEE
 
» Opportunities for Energy Storage: Assessing Whole-System Economic Benefits of Energy Storage in Future Electricity Systems
Abstract:
Any Cost-effective transition toward low-carbon electricity supply will necessitate improved system flexibility to address the challenges of increased balancing requirements and degradation in asset use. Energy storage (ES) represents a flexible option that can bring significant, fundamental economic benefits to various areas in the electric power sector, including reduced investment requirements for generation, transmission, and distribution infrastructure as well as reduced system operation and balancing costs. The additional flexibility offered by ES could also significantly reduce the requirement for investment in low-carbon generation capacity while achieving the established carbon intensity targets. Moreover, ES may present significant option value, as it can provide flexibility for dealing with uncertainty in future system development.
Autors: Goran Strbac;Marko Aunedi;Ioannis Konstantelos;Roberto Moreira;Fei Teng;Rodrigo Moreno;Danny Pudjianto;Adriana Laguna;Panagiotis Papadopoulos;
Appeared in: IEEE Power and Energy Magazine
Publication date: Sep 2017, volume: 15, issue:5, pages: 32 - 41
Publisher: IEEE
 
» Optical Emission Spectroscopy-Based Tomography for Compact Low-Pressure Microwave Plasma in a Multicusp
Abstract:
Microwave-induced argon and hydrogen plasmas confined in a compact multicusp (MC) are studied in the pressure range of 0.2–2 mtorr and at microwave powers of 216–324 W. Plasma parameters such as electron temperature () and density () are evaluated using optical emission spectroscopy (OES) and Langmuir probe (LP) measurements. The estimated and from OES measurements lie in the range of 5–13 eV and – cm, respectively, for the Ar and H2 plasmas, and are comparable to the values obtained from the LP measurements. The objective of this paper is to develop an emission tomographic measurement system for plasma confined in a compact MC. In general, OES is carried out to determine the wavelength of the most intense emitted light from the plasma, which is then applied to design the tomographic system to finally obtain a 2-D emission profile of light from the whole plasma cross section. Tomographic reconstruction of the plasma emission indicates two bright rings, one at the core and another near the plasma boundary, which are influenced by higher electron density at the core region and higher electron temperature near the electron cyclotron resonance zone.
Autors: Kavita Rathore;Sudeep Bhattacharjee;Dudh Nath Patel;Prabhat Munshi;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Sep 2017, volume: 45, issue:9, pages: 2492 - 2503
Publisher: IEEE
 
» Optical Gain Depending on Both Size Fluctuations of Quantum Dots and Temperature in InGaAs/GaAs QD-SOA
Abstract:
On the basis of the coupled rate equations of the carriers in different energy states, the optical gain of an InGaAs/GaAs quantum dot (QD) semiconductor optical amplifier (QD-SOA) related to both the standard deviation of QD relative size fluctuation and the temperature is numerically investigated with a fourth-order Runge–Kutta method. Our results show that the quasi-flat gain spectra with the full-width at half-maximum more than 150 nm overlapped by the optical gains of both the ground state (GS) and the excited state (ES) can be achieved by either injection current density or temperature. When a pump light is resonant to the GS transition, the peak gain of the GS is not only varied with pump power, but the peak gain of the ES is also changed with this one. The ES may exhibit abnormal gain saturation at room temperature (300 K), which is considerably different from those of bulk and quantum-well SOAs. We predict that the QD-SOA both acting as an optical amplifier is applied to dense wavelength division multiplexing systems and acting as an all-optical wavelength converter implements the wavelength conversion without inverse codes based on the cross gain modulation.
Autors: Zhenhua Hu;Bowen Xiang;Yunsheng Xing;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Sep 2017, volume: 64, issue:9, pages: 3683 - 3689
Publisher: IEEE
 
» Optical Heterodyne Microvibration Detection Based on All-Fiber Acousto-Optic Superlattice Modulation
Abstract:
We propose a configuration of optical heterodyne microvibration detection based on an all-fiber acousto-optic superlattice modulation structure that acts as both frequency shifter and reflector, simultaneously. The vibration information within the frequency range between 1 Hz and 150 kHz of a piezoelectric mirror has been experimentally measured by using this all-fiber optical heterodyne detection configuration. The minimal measurable vibration amplitude and the resolution are around 0.013 nm and 10 pm in the region of tens to hundreds of kilohertz, respectively. The configuration not only has advantages of compact size, easy alignment, and noncontact measurement, but also gains high accuracy, which provides a promising alternative and could be applied in the compact and portable instruments based on optical heterodyne detection.
Autors: Wending Zhang;Zhen Chen;Biqiang Jiang;Ligang Huang;Dong Mao;Feng Gao;Ting Mei;Dexing Yang;Lin Zhang;Jianlin Zhao;
Appeared in: Journal of Lightwave Technology
Publication date: Sep 2017, volume: 35, issue:18, pages: 3821 - 3824
Publisher: IEEE
 

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