Electrical and Electronics Engineering publications abstract of: 03-2017 sorted by title, page: 11

» Lateral Charge Transport in the Carbon-Doped Buffer in AlGaN/GaN-on-Si HEMTs
Abstract:
Dynamic and ramped substrate bias measurements are used to demonstrate size- and geometry-dependent dispersion in power transistors. This is due to a novel lateral transport mechanism in the semi-insulating carbon-doped GaN buffer in AlGaN/GaN high-electron-mobility transistors. We propose that the vertical field generates a 2-D hole gas (2DHG) at the bottom of the GaN:C layer, with hole flow extending outside the isolated area. The device-to-device variation is due to a combination of widely spaced preferential leakage paths through the structure and lateral transport from those paths to trapping sites. The spread of the 2DHG outside the active area of the device strongly affects the result of substrate ramp measurements producing major differences between single and multifinger devices. In dynamic recovery measurements, single-finger devices show large device-to-device variation, with multifinger devices showing a small variation with the transient comprising the superposition of the recovery transient of multiple small single-finger devices.
Autors: Indranil Chatterjee;Michael J. Uren;Serge Karboyan;Alexander Pooth;Peter Moens;Abhishek Banerjee;Martin Kuball;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 977 - 983
Publisher: IEEE
 
» Layered Downlink Precoding for C-RAN Systems With Full Dimensional MIMO
Abstract:
The implementation of a cloud radio access network (C-RAN) with full dimensional (FD) multiple-input multiple-output (MIMO) is faced with the challenge of controlling the fronthaul overhead for the transmission of baseband signals as the number of horizontal and vertical antennas grows larger. This paper proposes to leverage the special low-rank structure of the FD-MIMO channel, which is characterized by a time-invariant elevation component and a time-varying azimuth component, by means of a layered precoding approach, to reduce the fronthaul overhead. According to this scheme, separate precoding matrices are applied for the azimuth and elevation channel components, with different rates of adaptation to the channel variations and correspondingly different impacts on the fronthaul capacity. Moreover, we consider two different central unit (CU)–radio unit (RU) functional splits at the physical layer, namely, the conventional C-RAN implementation and an alternative one in which coding and precoding are performed at the RUs. Via numerical results, it is shown that the layered schemes significantly outperform conventional nonlayered schemes, particularly in the regime of low fronthaul capacity and a large number of vertical antennas.
Autors: Jinkyu Kang;Osvaldo Simeone;Joonhyuk Kang;Shlomo Shamai;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Mar 2017, volume: 66, issue:3, pages: 2170 - 2182
Publisher: IEEE
 
» Layered Graph Drawing for Visualizing Evaluation Structures
Abstract:
An evaluation structure is a hierarchical structure of human cognition extracted from interviews based on the evaluation grid method. An evaluation structure can be defined as a directed acyclic graph (DAG). The authors propose a layer-assignment method that is part of the Sugiyama framework, a popular method for drawing DAGs, to satisfy the requirements for drawing evaluation structures. Their evaluations demonstrate that the layered graph drawing produced by the proposed layer-assignment method is preferred by users and aids in the understanding of evaluation structures.
Autors: Yosuke Onoue;Nobuyuki Kukimoto;Naohisa Sakamoto;Kazuo Misue;Koji Koyamada;
Appeared in: IEEE Computer Graphics and Applications
Publication date: Mar 2017, volume: 37, issue:2, pages: 20 - 30
Publisher: IEEE
 
» Learning and Transferring Convolutional Neural Network Knowledge to Ocean Front Recognition
Abstract:
In this letter, we investigated how to apply a deep learning method, in particular convolutional neural networks (CNNs), to an ocean front recognition task. Exploring deep CNNs knowledge to ocean front recognition is a challenging task, because the training data is very scarce. This letter overcomes this challenge using a sequence of transfer learning steps via fine-tuning. The core idea is to extract deep knowledge of the CNN model from a large data set and then transfer the knowledge to our ocean front recognition task on limited remote sensing (RS) images. We conducted experiments on two different RS image data sets, with different visual properties, i.e., colorful and gray-level data, which were both downloaded from the National Oceanic and Atmospheric Administration (NOAA). The proposed method was compared with the conventional handcraft descriptor with bag-of-visual-words, original CNN model, and last-layer fine-tuned CNN model. Our method showed a significantly higher accuracy than other methods in both datasets.
Autors: Estanislau Lima;Xin Sun;Junyu Dong;Hui Wang;Yuting Yang;Lipeng Liu;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Mar 2017, volume: 14, issue:3, pages: 354 - 358
Publisher: IEEE
 
» Learning from Weak and Noisy Labels for Semantic Segmentation
Abstract:
A weakly supervised semantic segmentation (WSSS) method aims to learn a segmentation model from weak (image-level) as opposed to strong (pixel-level) labels. By avoiding the tedious pixel-level annotation process, it can exploit the unlimited supply of user-tagged images from media-sharing sites such as Flickr for large scale applications. However, these ‘free’ tags/labels are often noisy and few existing works address the problem of learning with both weak and noisy labels. In this work, we cast the WSSS problem into a label noise reduction problem. Specifically, after segmenting each image into a set of superpixels, the weak and potentially noisy image-level labels are propagated to the superpixel level resulting in highly noisy labels; the key to semantic segmentation is thus to identify and correct the superpixel noisy labels. To this end, a novel -optimisation based sparse learning model is formulated to directly and explicitly detect noisy labels. To solve the -optimisation problem, we further develop an efficient learning algorithm by introducing an intermediate labelling variable. Extensive experiments on three benchmark datasets show that our method yields state-of-the-art results given noise-free labels, whilst significantly outperforming the existing methods when the weak labels are also noisy.
Autors: Zhiwu Lu;Zhenyong Fu;Tao Xiang;Peng Han;Liwei Wang;Xin Gao;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Mar 2017, volume: 39, issue:3, pages: 486 - 500
Publisher: IEEE
 
» Learning Inverse Rig Mappings by Nonlinear Regression
Abstract:
We present a framework to design inverse rig-functions-functions that map low level representations of a character's pose such as joint positions or surface geometry to the representation used by animators called the animation rig. Animators design scenes using an animation rig, a framework widely adopted in animation production which allows animators to design character poses and geometry via intuitive parameters and interfaces. Yet most state-of-the-art computer animation techniques control characters through raw, low level representations such as joint angles, joint positions, or vertex coordinates. This difference often stops the adoption of state-of-the-art techniques in animation production. Our framework solves this issue by learning a mapping between the low level representations of the pose and the animation rig. We use nonlinear regression techniques, learning from example animation sequences designed by the animators. When new motions are provided in the skeleton space, the learned mapping is used to estimate the rig controls that reproduce such a motion. We introduce two nonlinear functions for producing such a mapping: Gaussian process regression and feedforward neural networks. The appropriate solution depends on the nature of the rig and the amount of data available for training. We show our framework applied to various examples including articulated biped characters, quadruped characters, facial animation rigs, and deformable characters. With our system, animators have the freedom to apply any motion synthesis algorithm to arbitrary rigging and animation pipelines for immediate editing. This greatly improves the productivity of 3D animation, while retaining the flexibility and creativity of artistic input.
Autors: Daniel Holden;Jun Saito;Taku Komura;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Publication date: Mar 2017, volume: 23, issue:3, pages: 1167 - 1178
Publisher: IEEE
 
» Learning the LMP-Load Coupling From Data: A Support Vector Machine Based Approach
Abstract:
This paper investigates the fundamental coupling between loads and locational marginal prices (LMPs) in security-constrained economic dispatch (SCED). Theoretical analysis based on multi-parametric programming theory points out the unique one-to-one mapping between load and LMP vectors. Such one-to-one mapping is depicted by the concept of system pattern region (SPR) and identifying SPRs is the key to understanding the LMP-load coupling. Built upon the characteristics of SPRs, the SPR identification problem is modeled as a classification problem from a market participant's viewpoint, and a Support Vector Machine based data-driven approach is proposed. It is shown that even without the knowledge of system topology and parameters, the SPRs can be estimated by learning from historical load and price data. Visualization and illustration of the proposed data-driven approach are performed on a 3-bus system as well as the IEEE 118-bus system.
Autors: Xinbo Geng;Le Xie;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1127 - 1138
Publisher: IEEE
 
» Left Ventricular Myocardial Segmentation in 3-D Ultrasound Recordings: Effect of Different Endocardial and Epicardial Coupling Strategies
Abstract:
Cardiac volume/function assessment remains a critical step in daily cardiology, and 3-D ultrasound plays an increasingly important role. Though development of automatic endocardial segmentation methods has received much attention, the same cannot be said about epicardial segmentation, in spite of the importance of full myocardial segmentation. In this paper, different ways of coupling the endocardial and epicardial segmentations are contrasted and compared with uncoupled segmentation. For this purpose, the B-spline explicit active surfaces framework was used; 27 3-D echocardiographic images were used to validate the different coupling strategies, which were compared with manual contouring of the endocardial and epicardial borders performed by an expert. It is shown that an independent segmentation of the endocardium followed by an epicardial segmentation coupled to the endocardium is the most advantageous. In this way, a framework for fully automatic 3-D myocardial segmentation is proposed using a novel coupling strategy.
Autors: João Pedrosa;Daniel Barbosa;Brecht Heyde;Frédéric Schnell;Assami Rösner;Piet Claus;Jan D’hooge;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Mar 2017, volume: 64, issue:3, pages: 525 - 536
Publisher: IEEE
 
» Leveraging Control and Monitoring Technologies: Reliability and Lower Costs for Electrical Trace-Heating Systems in Petrochemical Facilities
Abstract:
Electric trace heating is commonly used by the petrochemical industry for the freeze protection of water lines or the temperature maintenance of process fluids. An unreliable trace-heating system can impact the business significantly by damaging the process fluids/piping and potentially causing lost production. Controlling and monitoring the performance of trace heating is important to ensure that the processes are running as desired. This article focuses on the advances made by the trace-heating industry in control and monitoring technologies to improve the reliability of trace-heating systems as well as reduce their total installed costs. A real-world case study example is used to illustrate the reduction in total installed costs using control and monitoring capabilities.
Autors: Sudhir Thorat;Chris Thibodeau;Bill Collier;Huan Ngo;
Appeared in: IEEE Industry Applications Magazine
Publication date: Mar 2017, volume: 23, issue:2, pages: 62 - 73
Publisher: IEEE
 
» Leveraging Spectrum Sharing and Defragmentation to $p$ -Cycle Design in Elastic Optical Networks
Abstract:
In this letter, a new protection technique, namely Spectrum Shared pre-configured cycles (SS--cycles), is proposed for survivable elastic optical networks. SS--cycles permit to cut spectrum usage and spectrum fragmentation ratio (SFR) by leveraging special spectrum sharing among multiple -cycles that have common link(s). To compute SS--cycles, we first formulate an integer linear programming model to obtain the optimal solution in small instance, and then develop a time-efficient heuristic algorithm to solve large-scale instances. Simulation results have demonstrated that the proposed SS--cycles outperform conventional -cycles without spectrum sharing in terms of spectrum usage and SFR.
Autors: Min Ju;Fen Zhou;Shilin Xiao;Haitao Wu;
Appeared in: IEEE Communications Letters
Publication date: Mar 2017, volume: 21, issue:3, pages: 508 - 511
Publisher: IEEE
 
» Leveraging the Near–Far Effect for Improved Spatial-Reuse Scheduling in Underwater Acoustic Networks
Abstract:
We present a spatial reuse resource allocation scheme for underwater acoustic networks that organizes communications so as to avoid destructive collisions. One prime source of collisions in underwater acoustic networks is the so called near–far effect, where a node located farther from the receiver is jammed by a closer node. While common practice considers such a situation a challenge, in this paper we consider it a resource, and use it to increase the network throughput of spatial-reuse time-division multiple access. Our algorithm serves two types of communications: 1) contention-free and 2) opportunistic. Our objective is to maximize the time slot allocation, while guaranteeing a minimum per-node packet transmission rate. The result is an increase in the number of contention-free packets received, and a decrease in the scheduling delay of opportunistic packets. Numerical results show that, at a slight cost in terms of fairness, our scheduling solutions achieve higher throughput and lower transmission delay than benchmark spatial-reuse scheduling protocols. These results are verified in a field experiment conducted in the Garda Lake, Italy, where we demonstrated our solution using off-the-shelf acoustic modems. To allow the reproducibility of our results, we publish the implementation of our proposed algorithm.
Autors: Roee Diamant;Paolo Casari;Filippo Campagnaro;Michele Zorzi;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1480 - 1493
Publisher: IEEE
 
» LFSR-Based Generation of Multicycle Tests
Abstract:
This paper describes a procedure for computing a multicycle test set whose scan-in states are compressed into seeds for a linear-feedback shift register, and whose primary input vectors are held constant during the application of a multicycle test. The goal of computing multicycle tests is to provide test compaction that reduces both the test application time and the test data volume. To avoid sequential test generation, the procedure uses a single-cycle test set to guide the computation of multicycle tests. The procedure optimizes every multicycle test, and increases the number of faults it detects, by adjusting its seed, primary input vector, and number of functional clock cycles. Optimizing the seed instead of the scan-in state avoids the computation of scan-in states for which seeds do not exist. Experimental results for benchmark circuits are presented to demonstrate the effectiveness of the procedure.
Autors: Irith Pomeranz;
Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Publication date: Mar 2017, volume: 36, issue:3, pages: 503 - 507
Publisher: IEEE
 
» Lifetime Extension of Software Execution Subject to Aging
Abstract:
Software aging is a phenomenon of progressive degradation of software execution environment caused by software faults. In this paper, we propose software life-extension as an operational countermeasure against software aging and present the mathematical foundations of software life-extension by means of stochastic modeling. A semi-Markov process is used to capture the behavior of a system with software life-extension and to analyze the system's availability and completion times of jobs running on it. The semi-Markov process can correctly model the time-based life-extension and allows us to derive the optimal trigger for starting life-extension in terms of system availability and mean job completion time. We also present an effective combination of software life-extension and software rejuvenation that can maximize the system availability compared with a system using either rejuvenation or software life-extension.
Autors: Fumio Machida;Jianwen Xiang;Kumiko Tadano;Yoshiharu Maeno;
Appeared in: IEEE Transactions on Reliability
Publication date: Mar 2017, volume: 66, issue:1, pages: 123 - 134
Publisher: IEEE
 
» Lighting Up with a Dual-Purpose Driver: A Viable Option for a Light-Emitting Diode Driver for Visible Light Communication
Abstract:
This article presents a dual-purpose offline light-emitt ing diode (LED) driver using a single-stage buck?boost?buck (S2-B3) converter. The proposed (S2-B3) converter provides combined illumination control and visible light communication (VLC) along with power factor correction (PFC) and is designed to operate the buck?boost section in discontinuous conduction mode (DCM) with constant duty ratio to provide PFC. The buck section of the converter is operated in continuous conduction mode (CCM) with average current mode control (ACMC) to realize a constant current source for a high-brightness LED (HB-LED) load. The HBLED load connected to the converter is switched on and off at 2 MHz to facilitate both illumination and VLC . Data transfer and illumination control are achieved through variable pulse position modulation (VPPM) and high-frequency pulsewidth modulation (PWM) dimming, respectively. The modeling and design of the proposed (S2-B3) converter with a VPPM modulation scheme are detailed. Simulation and experimental results of the proposed converter with 500-lm output and 2-Mb/s data transfer of phosphor-converted (PC)-white LEDs for 110/120-V ac input are demonstrated.
Autors: Kumar Modepalli;Leila Parsa;
Appeared in: IEEE Industry Applications Magazine
Publication date: Mar 2017, volume: 23, issue:2, pages: 51 - 61
Publisher: IEEE
 
» Lightweight Authentication and Privacy-Preserving Scheme for V2G Connections
Abstract:
Vehicle-to-grid (V2G) connection allows a two-way electricity transmission between electric vehicles (EVs) and the power grid for achieving many known benefits. However, V2G connections suffer from certain security threats, such as to the EV's privacy and in authenticating the EV to the grid. In this paper, we propose a lightweight secure and privacy-preserving V2G connection scheme in which the power grid assures the confidentiality and integrity of exchanged information during (dis)charging electricity sessions and overcomes the EVs' authentication problem. The proposed scheme guarantees the financial profits of the grid and prevents EVs from acting maliciously. Meanwhile, EVs preserve their private information by generating their own pseudonym identities. In addition, the scheme maintains accountability for the electricity exchange trade. Furthermore, the proposed scheme provides these security requirements by lightweight overhead, as it diminishes the number of exchanged messages during (dis)charging sessions. Simulation results demonstrate that the proposed scheme significantly reduces the total communication and computation load for V2G connection, particularly for EVs.
Autors: Asmaa Abdallah;Xuemin Sherman Shen;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Mar 2017, volume: 66, issue:3, pages: 2615 - 2629
Publisher: IEEE
 
» Linear and Nonlinear Precoding Based Dynamic Spectrum Management for Downstream Vectored G.fast Transmission
Abstract:
In the G.fast digital subscriber line frequency range (up to 106 or 212 MHz), where crosstalk channels may even become larger than direct channels, linear zero-forcing (ZF) precoding is no longer near-optimal for downstream (DS) vectored transmission. To improve performance, we develop a novel low-complexity algorithm for both linear and nonlinear precoding-based dynamic spectrum management that maximizes the weighted sum-rate under realistic per-line total power and per-tone spectral mask constraints. It applies to DS scenarios with a single copper line at each customer site [i.e., broadcast channel (BC) scenarios], as well as to DS scenarios with multiple copper lines at some or all customer sites (i.e., the so-called multiple-input-multiple-output-BC scenarios). The algorithm alternates between precoder and equalizer optimization, where the former relies on a Lagrange multiplier based transformation of the DS dual decomposition approach formulation into its dual upstream (US) formulation, together with a low-complexity iterative fixed-point formula to solve the resulting US problem. Simulations with measured G.fast channel data of a very high crosstalk cable binder are provided revealing a significantly improved performance of this algorithm over ZF techniques for various scenarios, and in addition, a faster convergence rate compared with the state-of-the-art WMMSE algorithm.
Autors: Wouter Lanneer;Paschalis Tsiaflakis;Jochen Maes;Marc Moonen;
Appeared in: IEEE Transactions on Communications
Publication date: Mar 2017, volume: 65, issue:3, pages: 1247 - 1259
Publisher: IEEE
 
» Linear Degrees of Freedom for $K$ -user MISO Interference Channels With Blind Interference Alignment
Abstract:
In this paper, we characterize the degrees of freedom (DoF) for -user multiple-input single-output interference channels with reconfigurable antennas, which have -preset modes at the receivers, assuming linear coding strategies in the absence of channel state information at the transmitters, i.e., blind interference alignment. Our linear DoF converse builds on the lemma that if a set of transmit symbols is aligned at their common unintended receivers, those symbols must have independent signal subspace at their corresponding receivers. This lemma arises from the inherent feature that channel state’s changing patterns of the links towards the same receiver are always identical, assuming that the coherence time of the channel is long enough. We derive an upper bound for the linear sum DoF, and propose an achievable scheme that exactly achieves the linear sum DoF upper bound when both of the and are integers, where denotes the optimal number of preset modes out of preset modes. For the other cases, where either or is not an integer, we only give some guidelines how the interfering signals are aligned at the receivers to achieve the upper bound. As an extension, we also show the linear sum DoF upper bound for downlink/u- link cellular networks.
Autors: Heecheol Yang;Wonjae Shin;Jungwoo Lee;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1921 - 1934
Publisher: IEEE
 
» Linear Detection of a Weak Signal in Additive Cauchy Noise
Abstract:
The detection of a weak signal in additive Cauchy noise is of great importance in many applications. A locally optimum detector (LOD) exists for such a scenario; however, it is non-linear in nature. In general, implementation of non-linear detectors is difficult in practice, and linear detectors with good properties, such as high asymptotic relative efficiency (ARE) with respect to the LOD, are often desirable. In this paper, we propose a linear detector for a weak signal in additive Cauchy noise. The proposed test statistic is a linear combination of order statistics. For the special case of a constant signal in additive Cauchy noise, we prove the asymptotic normality of the trimmed linear detector, and show that the ARE of the trimmed linear detector with respect to the LOD is unity. Extensive simulation results are provided to demonstrate that the loss in the performance of the linear detector is very small compared with the non-linear LOD. We also discuss the hardware complexities of the LOD and the linear detector, and demonstrate the advantages of the linear detector over the LOD, in terms of hardware implementation.
Autors: Siva Ram Krishna Vadali;Priyadip Ray;Subrahmanyam Mula;Pramod K. Varshney;
Appeared in: IEEE Transactions on Communications
Publication date: Mar 2017, volume: 65, issue:3, pages: 1061 - 1076
Publisher: IEEE
 
» Linear Machine Solution to Point Location Problem
Abstract:
Linear machine has been recently proposed as an elegant solution for solving the point location problem arising in multi-parametric programming (mp-P) based online optimization. Linear machine associates a linear discriminant function with each polytopic region in the parametric space. The solution to the point location problem is then obtained by simply evaluating these discriminant functions and finding their maximum value. In this technical note, we rigorously establish the correctness of the linear machine generation procedure and identify a necessary condition for existence of linear machine. A modified procedure, involving systematic subdivision of the parametric space, is proposed when this condition is not satisfied. Analysis of complexity and storage requirements, along with computational experiments on a large sized example, indicate that linear machine can be an efficient tool for solving the point location problem.
Autors: Astha Airan;Mani Bhushan;Sharad Bhartiya;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Mar 2017, volume: 62, issue:3, pages: 1403 - 1410
Publisher: IEEE
 
» Linear Quadratic Risk-Sensitive and Robust Mean Field Games
Abstract:
This paper considers two classes of large population stochastic differential games connected to optimal and robust decentralized control of large-scale multiagent systems. The first problem (P1) is one where each agent minimizes an exponentiated cost function, capturing risk-sensitive behavior, whereas in the second problem (P2 ) each agent minimizes a worst-case risk-neutral cost function, where the “worst case” stems from the presence of an adversary entering each agent’s dynamics characterized by a stochastic differential equation. In both problems, the individual agents are coupled through the mean field term included in each agent’s cost function, which captures the average or mass behavior of the agents. We solve both P1 and P2 via mean field game theory. Specifically, we first solve a generic risk-sensitive optimal control problem and a generic stochastic zero-sum differential game, where the corresponding optimal controllers are applied by each agent to construct the mean field systems of P1 and P2. We then characterize an approximated mass behavior effect on an individual agent via a fixed-point analysis of the mean field system. For each problem, P1 and P2, we show that the approximated mass behavior is in fact the best estimate of the actual mass behavior in various senses as the population size, , goes to infinity. Moreover, we show that for finite , there exist - Nash equilibria for both P1 and P2, where the corresponding individual Nash strategies are decentralized in terms of local state information and the approximated- mass behavior. We also show that can be taken to be arbitrarily small when is sufficiently large. We show that the - Nash equilibria of P1 and P2 are partially equivalent in the sense that the individual Nash strategies share identical control laws, but the approximated mass behaviors for P1 and P2 are different, since in P2, the mass behavior is also affected by the associated worst-case disturbance. Finally, we prove that the Nash equilibria for P1 and P2 both feature robustness, and as the parameter characterizing this robustness becomes infinite, the two Nash equilibria become identical and equivalent to that of the risk-neutral case, as in the one-agent risk-sensitive and robust control theory.
Autors: Jun Moon;Tamer Başar;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Mar 2017, volume: 62, issue:3, pages: 1062 - 1077
Publisher: IEEE
 
» Linking Statistical and Ecological Theory: Hubbell's Unified Neutral Theory of Biodiversity as a Hierarchical Dirichlet Process
Abstract:
Neutral models which assume ecological equivalence between species provide null models for community assembly. In Hubbell's unified neutral theory of biodiversity (UNTB), many local communities are connected to a single metacommunity through differing immigration rates. Our ability to fit the full multisite UNTB has hitherto been limited by the lack of a computationally tractable and accurate algorithm. We show that a large class of neutral models with this mainland-island structure but differing local community dynamics converge in the large population limit to the hierarchical Dirichlet process. Using this approximation we developed an efficient Bayesian fitting strategy for the multisite UNTB. We can also use this approach to distinguish between neutral local community assembly given a nonneutral metacommunity distribution and the full UNTB where the metacommunity too assembles neutrally. We applied this fitting strategy to both tropical trees and a data set comprising 570 851 sequences from 278 human gut microbiomes. The tropical tree data set was consistent with the UNTB but for the human gut neutrality was rejected at the whole community level. However, when we applied the algorithm to gut microbial species within the same taxon at different levels of taxonomic resolution, we found that species abundances within some genera were almost consistent with local community assembly. This was not true at higher taxonomic ranks. This suggests that the gut microbiota is more strongly niche constrained than macroscopic organisms, with different groups adopting different functional roles, but within those groups diversity may at least partially be maintained by neutrality. We also observed a negative correlation between body mass index and immigration rates within the family Ruminococcaceae. This provides a novel interpretation of the impact of obesity on the human microbiome s a relative increase in the importance of local growth versus external immigration within this key group of carbohydrate degrading organisms.
Autors: Keith Harris;Todd L. Parsons;Umer Z. Ijaz;Leo Lahti;Ian Holmes;Christopher Quince;
Appeared in: Proceedings of the IEEE
Publication date: Mar 2017, volume: 105, issue:3, pages: 516 - 529
Publisher: IEEE
 
» LLR Reliability Improvement for Multilayer Signals
Abstract:
The limitations and rigidness of current use of spectrum resources have fostered the design of new power multiplexing techniques to improve frequency efficiency and flexibility. These techniques are based on the simultaneous transmission of different services on the same channel with different power distribution. At the receiver side Log-likelihood ratio (LLR) probability density functions have been so far optimized for single layer systems, so the reception quality of multilayer signals with the existing LLR algorithms is degraded. This paper proposes a new LLR probability density function, including corrections for the multilayer influence, in order to improve reception performance. Simulation results are also included to test the performance improvement in terms of the receiving SNR threshold.
Autors: Cristina Regueiro;Jon Barrueco;Jon Montalban;Pablo Angueira;Juan Luis Ordiales;Manuel Velez;
Appeared in: IEEE Transactions on Broadcasting
Publication date: Mar 2017, volume: 63, issue:1, pages: 275 - 281
Publisher: IEEE
 
» Load Aggregation From Generation-Follows-Load to Load-Follows-Generation: Residential Loads
Abstract:
The growing interest in optimizing the generation, distribution, and delivery of electric power have motivated the implementation of several smart grid functions in many power systems around the globe. Among such functions are the peak-load management, demand response, direct load control, and integration of distributed power generation. Nowadays, smart grid functions are being implemented for industrial, residential, and/or commercial loads. One of the key requirements for implementing smart grid functions is the accurate and reliable load aggregation. The bottom-up, coordinated, and bus-split aggregation methods have been found applicable for different load types that are included in smart grid functions. This paper reviews the methods and approaches for performing the load aggregation, and provides a discussion for the critical role of load aggregation in power systems operating and smart grid functions. In addition, this paper discusses the applicability of the load aggregation methods in smart grid functions for residential loads.
Autors: S. A. Saleh;Petrus Pijnenburg;Eduardo Castillo-Guerra;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 833 - 842
Publisher: IEEE
 
» Load Flow Calculation with Voltage Regulators Bidirectional Mode and Distributed Generation
Abstract:
This letter presents a problem of calculating load flow in distribution feeders via the conventional three-phase backward/forward sweep method when voltage regulators in the bidirectional mode are experiencing reverse flow due to power injection from distributed generation downstream the regulators. It also presents a simple but effectively modification in the algorithm of that method to overcome the problem. A modified version of the IEEE 34 buses distribution test feeder will be used to demonstrate the problem and the proposed algorithm solution.
Autors: Julio A. D. Massignan;Benvindo R. Pereira;João B. A. London;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1576 - 1577
Publisher: IEEE
 
» Load-Stress Test of Massive Handovers for LTE Two-Hop Architecture in High-Speed Trains
Abstract:
Load-stress test is the experimental performance analysis in extreme traffic and density conditions, routinely required to validate any innovative radio access solution. This article focuses on load-stress test specifically designed for the two-hop architecture that enables the onboard connectivity in HSTs. The load-stress condition of train-to-infrastructure communication for a massive number of onboard UEs is very challenging, as it needs to account for extreme conditions and a complex testing environment. The load-stress method proposed in this article is for a ground network supporting onboard wireless connectivity in HSTs, and is validated for commercial eNBs from LTE cellular networks (Rel-11). The in-lab experimental setup is arranged by virtualizing multiple eNBs serving multiple cells, arranged sequentially along a line to simulate the HST track with a massive number of active onboard UEs. The focus of the experimental load-stress test is the analysis of the impact of Doppler shift and interruptions caused by the frequent HOs of multiple consecutive groups of UEs deployed in HST carriages at the speed of 300 km/h. The HO interruption time is characterized statistically based on the number of active UEe. The consequent impairments on the experienced QoS for high-throughput and low-latency services such as FTP and VoLTE are verified. This article validates experimentally the traffic and HO latency improvements (approximately threefold) in a multi-cell access scheme when the coverage of every single carriage is augmented by fixed directional antennas to offload UEs toward far-away eNBs along the train track.
Autors: Ali Parichehreh;Umberto Spagnolini;Paolo Marini;Alberto Fontana;
Appeared in: IEEE Communications Magazine
Publication date: Mar 2017, volume: 55, issue:3, pages: 170 - 177
Publisher: IEEE
 
» Local Pattern Collocations Using Regional Co-occurrence Factorization
Abstract:
Human vision benefits a lot from pattern collocations in visual activities such as object detection and recognition. Usually, pattern collocations display as the co-occurrences of visual primitives, e.g., colors, gradients, or textons, in neighboring regions. In the past two decades, many sophisticated local feature descriptors have been developed to describe visual primitives, and some of them even take into account the co-occurrence information for improving their discriminative power. However, most of these descriptors only consider feature co-occurrence within a very small neighborhood, e.g., 8-connected or 16-connected area, which would fall short in describing pattern collocations built up by feature co-occurrences in a wider neighborhood. In this paper, we propose to describe local pattern collocations by using a new and general regional co-occurrence approach. In this approach, an input image is first partitioned into a set of homogeneous superpixels. Then, features in each superpixel are extracted by a variety of local feature descriptors, based on which a number of patterns are computed. Finally, pattern co-occurrences within the superpixel and between the neighboring superpixels are calculated and factorized into a final descriptor for local pattern collocation. The proposed regional co-occurrence framework is extensively tested on a wide range of popular shape, color, and texture descriptors in terms of image and object categorizations. The experimental results have shown significant performance improvements by using the proposed framework over the existing popular descriptors.
Autors: Qin Zou;Lihao Ni;Qian Wang;Zhongwen Hu;Qingquan Li;Song Wang;
Appeared in: IEEE Transactions on Multimedia
Publication date: Mar 2017, volume: 19, issue:3, pages: 492 - 505
Publisher: IEEE
 
» Local Recovery for High Availability in Strongly Consistent Cloud Services
Abstract:
Emerging cloud-based network services must deliver both good performance and high availability. Achieving both of these goals requires content replication across multiple sites. Many cloud-based services either require or would benefit from the semantics and simplicity of strong consistency. However, replication techniques for strong consistency can severely limit the availability of replicated services when recovering large data objects over wide-area links. To address this problem, we present the design and implementation of Zorfu, a hierarchical system architecture for replication across data centers. The primary contribution of Zorfu is a local recovery technique that significantly increases availability of replicated strongly consistent services. Local recovery achieves this by reducing the recovery time by an order of magnitude, while imposing only a negligible latency overhead. Experimental results show that Zorfu can recover a 100 MB object in 4 ms.
Autors: James W. Anderson;Hein Meling;Alexander Rasmussen;Amin Vahdat;Keith Marzullo;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Mar 2017, volume: 14, issue:2, pages: 172 - 184
Publisher: IEEE
 
» Local Spectral Analysis of the Cerebral Cortex: New Gyrification Indices
Abstract:
Gyrification index (GI) is an appropriate measure to quantify the complexity of the cerebral cortex. There is, however, no universal agreement on the notion of surface complexity and there are various methods in literature that evaluate different aspects of cortical folding. In this paper, we give two intuitive interpretations on folding quantification based on the magnitude and variation of the mean curvature of the cortical surface. We then present a local spectral analysis of the mean curvature to introduce two local gyrification indices that satisfy our interpretations. For this purpose, the graph windowed Fourier transform is extended to the framework of surfaces discretized with triangular meshes. An adaptive window function is also proposed to deal with the intersubject cortical size variability. The intrinsic nature of the method allows us to compute the degree of folding at different spatial scales. Our experiments show that while more classical surface area-based GIs may fail at differentiating deep folds from very convoluted ones, our spectral GIs overcome this issue. The method is applied to the cortical surfaces of 124 healthy adult subjects of OASIS database and average gyrification maps are computed and compared with other GI definitions. In order to illustrate the capacity of our method to capture and quantify important aspects of gyrification, we study the relationship between brain volume and cortical complexity, and design a scaling analysis with a power law model. Results indicate an allometric relation and confirm the well-known observations that larger brains are more folded. We also perform the scaling analysis at the vertex level to investigate how the degree of folding varies locally with the brain volume. Results reveal that in our healthy adult brain database, cortical regions which are the least folded on average show an increased folding complexity when brain size increases.
Autors: Hamed Rabiei;Frédéric Richard;Olivier Coulon;Julien Lefèvre;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Mar 2017, volume: 36, issue:3, pages: 838 - 848
Publisher: IEEE
 
» Localized Rotor Overheating of Large Direct on Line (DOL) Motors
Abstract:
Most often, serious reliability problems with large motors particularly synchronous motors may simply go unnoticed especially if the industrial facility's operation is a priority. The nature of such problems is not very well known in industrial applications and can be difficult to detect in the early stages of its development until a motor failure occurs. Localized rotor overheating, commonly known as hot spots or black marks for large motors and specifically synchronous motors, is one example of such a scenario. This paper provides insights to the nature of the localized rotor overheating for Direct on Line large motors in general, problem detection methods, and proposes possible rectification means to definitively resolve the problem.
Autors: Khalid S. Al-Najdi;Juhani Mantere;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1605 - 1616
Publisher: IEEE
 
» LORA: Loss Differentiation Rate Adaptation Scheme for Vehicle-to-Vehicle Safety Communications
Abstract:
The existing study shows that safety applications supported by vehicle-to-vehicle (V2V) communications have the potential to address 80% of all road crash issues. IEEE 802.11p is a key enabling technology to support V2V safety applications. To meet the stringent delay and reliability requirements of these applications, rate adaptation (RA) approaches have been proposed to determine the optimal data transmission rate, according to the channel conditions such as packet losses. However, existing RA solutions cannot be directly applied to V2V safety communications in highway scenarios, which exhibit lots of dynamics and severe packet losses. Moreover, physical (PHY)-layer channel fading and medium-access-control (MAC)-layer interference contribute differently to the packet losses and, thus, should be treated separately. To address these issues, in this paper, we propose a LOss differentiation RA (LORA) scheme. LORA can estimate the average packet loss rate (PLR) for each sender and differentiate the fading losses from the interference losses. Extensive evaluation results demonstrate that LORA can provide reliability guarantees for V2V safety applications, as well as a response to environment changes in a real-time manner.
Autors: Yuan Yao;Xi Chen;Lei Rao;Xue Liu;Xingshe Zhou;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Mar 2017, volume: 66, issue:3, pages: 2499 - 2512
Publisher: IEEE
 
» Loss Allocation for Weakly Meshed Distribution System Using Analytical Formulation of Shapley Value
Abstract:
A practical loss allocation method should consider size, distance from source, and network usage of its’ participants. The power flow pattern in distribution network has changed over a period due to increased integration of distributed generation (DG) and hence, the equivalent distance and usage of network have changed for the conventional distribution network. The regulators require a fair and robust model for loss allocation which should be able to discriminate between the contributions of multiple participants. The loss allocation techniques proposed earlier in the literature either require additional quantities over and above power flow solution or are specifically developed only for radial distribution networks. This paper presents a cooperative game approach which provides stable solution integrated with appropriate penalties or rewards to participants. The proposed method provides an analytical solution which is solved using Shapley value for radial as well as weakly meshed distribution network. The memory and computational burden with the Shapley value have been overcome by a final analytical formula that satisfies the axioms of fairness. The use of the method is straightforward without any assumptions and requires only network data and power flow solution. The results are illustrated using different scenarios of DG output levels and network topologies and compared with other methods to establish its effectiveness.
Autors: Satish Sharma;A. R. Abhyankar;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1369 - 1377
Publisher: IEEE
 
» Low Cost, Large Area, Flexible Graphene Nanocomposite Films for Energy Harvesting Applications
Abstract:
In this paper, we report a robust and a low-cost spin coating approach for fabrication of large area flexible piezoelectric nanocomposite generator device for harvesting biomechanical motions. In order to develop the piezoelectric nanocomposite, ZnO and BaTiO3 were used as filler materials for realization of piezoelectric nanogenerator. Serial stretching and bending tests over these devices illustrated generation of maximum open-circuit voltage of ∼237 and ∼736 mV for ZnO and BaTiO3, respectively. Furthermore, we also demonstrated a 2 × enhancement in output voltage performance of nanogenerator by adding graphene platelets to these diphasic piezoelectric nanocomposite systems.
Autors: Manoj Kandpal;Vijay Palaparthy;Nikhilendu Tiwary;V. Ramgopal Rao;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Mar 2017, volume: 16, issue:2, pages: 259 - 264
Publisher: IEEE
 
» Low-Complexity Decoding Algorithms for the LDM Core Layer at Fixed Receivers in ATSC 3.0
Abstract:
Gallager’s decoding algorithms (GDB) and (GDE) for low-density parity-check codes have much lower computational complexity and much less required memory size than the sum-product algorithm (SPA). This is because GDB and GDE only use binary or integer operations, while the SPA requires real operations and a look-up table. However, they are hardly used in commercial communication systems since they have a worse performance than the SPA. Layered-division multiplexing (LDM) is considered in ATSC 3.0 in order to deliver multiple broadcasting streams with distinct robustness in a single radio frequency channel. Due to the unique characteristic of the LDM, we propose to use GDB or GDE rather than the SPA for decoding the core layer signal at fixed receivers. Numerical results show that the computational complexity and the required memory size can be reduced without any performance loss by about 50 percent and 80 percent, respectively, when GDB and GDE are employed.
Autors: Sunghye Cho;Youngjun Hwang;Seho Myung;Kyeongcheol Yang;
Appeared in: IEEE Transactions on Broadcasting
Publication date: Mar 2017, volume: 63, issue:1, pages: 293 - 303
Publisher: IEEE
 
» Low-Complexity Modeling of Partially Available Second-Order Statistics: Theory and an Efficient Matrix Completion Algorithm
Abstract:
State statistics of linear systems satisfy certain structural constraints that arise from the underlying dynamics and the directionality of input disturbances. In the present paper, we study the problem of completing partially known state statistics. Our aim is to develop tools that can be used in the context of control-oriented modeling of large-scale dynamical systems. For the type of applications we have in mind, the dynamical interaction between state variables is known while the directionality and dynamics of input excitation is often uncertain. Thus, the goal of the mathematical problem that we formulate is to identify the dynamics and directionality of input excitation in order to explain and complete observed sample statistics. More specifically, we seek to explain correlation data with the least number of possible input disturbance channels. We formulate this inverse problem as rank minimization, and for its solution, we employ a convex relaxation based on the nuclear norm. The resulting optimization problem is cast as a semidefinite program and can be solved using general-purpose solvers. For problem sizes that these solvers cannot handle, we develop a customized alternating minimization algorithm (AMA). We interpret AMA as a proximal gradient for the dual problem and prove sublinear convergence for the algorithm with fixed step-size. We conclude with an example that illustrates the utility of our modeling and optimization framework and draw contrast between AMA and the commonly used alternating direction method of multipliers (ADMM) algorithm.
Autors: Armin Zare;Yongxin Chen;Mihailo R. Jovanović;Tryphon T. Georgiou;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Mar 2017, volume: 62, issue:3, pages: 1368 - 1383
Publisher: IEEE
 
» Low-Complexity Near-Optimal Iterative Sequential Detection for Uplink Massive MIMO Systems
Abstract:
A novel low-complexity iterative sequential detection algorithm is proposed for near-optimal detection in uplink massive multiple-input multiple-output systems. In every iteration of the proposed algorithm, symbol transmitted from each user is detected sequentially while nulling the interference from all the other users. In contrast with recently proposed methods such as polynomial expansion, dual band Newton iteration, and Jacobi iteration, the proposed algorithm performs superior in terms of precision and computational complexity, and achieves better performance when the number of users increases. Simulation results validate superiority of the proposed algorithm over the recently reported methods.
Autors: Manish Mandloi;Vimal Bhatia;
Appeared in: IEEE Communications Letters
Publication date: Mar 2017, volume: 21, issue:3, pages: 568 - 571
Publisher: IEEE
 
» Low-Frequency DC-Link Ripple Elimination in Power Converters With Reduced Capacitance by Multiresonant Direct Voltage Regulation
Abstract:
In this paper, a method for suppressing the low-frequency portion of dc-link ripple inevitably present in power conversion systems with reduced capacitance is proposed. The discussed active capacitance reduction circuitry (consisting of a feedback-controlled shunt-connected bidirectional buck-boost converter, terminated by a small auxiliary capacitance) directly regulates the dc-link voltage, utilizing a dual-loop control structure with parallel-connected multiresonant-bank-enhanced voltage loop stabilizing controller to achieve nearly constant, low-frequency-ripple-free steady-state dc-link voltage. Consequently, the proposed active capacitance reduction system may be perceived as a virtual infinite capacitor from the dc link point of view. The suggested circuitry is successfully applied to a single-phase commercial power factor correction front end in a nearly plug-and-play fashion. The control algorithm effectiveness is fully supported by simulations and experimental results.
Autors: Martin Mellincovsky;Vladimir Yuhimenko;Mor Mordechai Peretz;Alon Kuperman;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2015 - 2023
Publisher: IEEE
 
» Low-Frequency State-Space Model for the Five-Level Unidirectional T-Rectifier
Abstract:
This paper presents the analysis and the validation of the large-signals model of a new five-level T-type unidirectional three-phase rectifier topology known as 5L T-RECT. Proposed modeling approach is mainly based on the well-known state-space averaging technique. According to this technique, the averaging process is applied across one pulse width modulation sampling period , thus resulting in the basic 5L T-RECT mathematical model. Consequently, the ac–dc steady-state operation is analyzed through the achieved model. The large-signals model of the 5L T-RECT has been verified by means of the direct comparison with the converter full digital-switching model, realized in the MATLAB/Simulink environment. Simulation results exhibit a good matching with the proposed average model.
Autors: Marco Di Benedetto;Alessandro Lidozzi;Luca Solero;Fabio Crescimbini;Petar J. Grbovic;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1127 - 1137
Publisher: IEEE
 
» Low-Power and Compact Analog-to-Digital Converter Using Spintronic Racetrack Memory Devices
Abstract:
Current-induced domain wall (DW) motion in spintronic racetrack memory promises energy-efficient analog computation using compact magnetic nanowires. This paper explores the feasibility of analog-to-digital converter (ADC) based on current-induced DW motion and introduces an n-bit ADC using n racetrack magnetic nanowires. With each magnetic nanowire having a different configuration granularity, an n-bit binary or gray code is generated simultaneously. The proposed ADC structure achieves 21 fJ/conversion-step at 20 MHz with an area of about . The racetrack ADC is suitable for applications requiring dense ADC arrays, such as image sensors. This paper describes one ultrahigh speed digital pixel sensor imaging system benefiting from the racetrack ADC.
Autors: Qing Dong;Kaiyuan Yang;Laura Fick;David Fick;David Blaauw;Dennis Sylvester;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Mar 2017, volume: 25, issue:3, pages: 907 - 918
Publisher: IEEE
 
» Low-Power Miniature $K$ -Band Sensors for Dielectric Characterization of Biomaterials
Abstract:
This paper presents the design and comparison of three -band sensing oscillators in the standard 0.25- SiGe:C BiCMOS technology featuring an open stub, a shunt stub, and a combination of both. The different stub types are combined with the capacitive and/or inductive elements of the particular oscillator and serve as the sensing elements in the respective setup. The input impedances of the stubs depend on the permittivity of the medium. Therefore, the oscillation frequencies and the output power correspond to the dielectric material under test (MUT). The sensor response to different dielectric properties has been investigated using different compositions of methanol-ethanol solutions. In the conducted experiments, the proposed architectures show a maximum frequency shift of 5% (27.8–26.4 GHz) for a change in permittivity of 2.4 (4.1–6.5) of the MUT. Each of three sensors has a chip area of 0.6 mm2 and consumes less than a 12-mW power. The proposed sensor is a potential component for future low-power frontends to perform minimally invasive investigations of biomaterials.
Autors: Farabi Ibne Jamal;Subhajit Guha;Mohamed Hussein Eissa;Johanes Borngräber;Chafik Meliani;Herman Jalli Ng;Dietmar Kissinger;Jan Wessel;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Mar 2017, volume: 65, issue:3, pages: 1012 - 1023
Publisher: IEEE
 
» Low-Power Scan-Based Built-In Self-Test Based on Weighted Pseudorandom Test Pattern Generation and Reseeding
Abstract:
A new low-power (LP) scan-based built-in self-test (BIST) technique is proposed based on weighted pseudorandom test pattern generation and reseeding. A new LP scan architecture is proposed, which supports both pseudorandom testing and deterministic BIST. During the pseudorandom testing phase, an LP weighted random test pattern generation scheme is proposed by disabling a part of scan chains. During the deterministic BIST phase, the design-for-testability architecture is modified slightly while the linear-feedback shift register is kept short. In both the cases, only a small number of scan chains are activated in a single cycle. Sufficient experimental results are presented to demonstrate the performance of the proposed LP BIST approach.
Autors: Dong Xiang;Xiaoqing Wen;Laung-Terng Wang;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Mar 2017, volume: 25, issue:3, pages: 942 - 953
Publisher: IEEE
 
» Low-Profile Compact Dual-Band Unit Cell for Polarizing Surfaces Operating in Orthogonal Polarizations
Abstract:
This communication introduces a novel periodic reflector which provides linear to circular polarization (CP) conversion in two frequency bands. Significantly, the reflector converts a slant 45° linearly polarized wave into two orthogonal CPs over two separate frequency bands while further the unit cell dimensions are maintained below the critical grating lobe limit of half wavelength. Unlike previous designs providing this performance, which are based on linear dipole elements, miniaturization is here achieved by exploiting resonances in both TE and TM polarized waves. The operating principle of the polarizer is discussed and a parametric study is presented to derive design guidelines. A prototype working in the satellite Ku-band has been designed and tested to validate the proposed design. The proposed polarizer can find applications in multiple-beam satellite antenna systems in order to reduce the number of reflector apertures in a single-feed-per-beam configuration.
Autors: Wenxing Tang;Salvador Mercader-Pellicer;George Goussetis;Herve Legay;Nelson J. G. Fonseca;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Mar 2017, volume: 65, issue:3, pages: 1472 - 1477
Publisher: IEEE
 
» Low-Profile, Electrically Small, Huygens Source Antenna With Pattern-Reconfigurability That Covers the Entire Azimuthal Plane
Abstract:
A pattern-reconfigurable, low-profile, efficient, electrically small, near-field resonant parasitic (NFRP), Huygens source antenna is presented. The design incorporates both electric and magnetic NFRP elements. The electric ones are made reconfigurable by the inclusion of a set of p-i-n diodes. By arranging these electric and magnetic NFRP elements properly, a set of three Huygens sources are attained, each covering a 120° sector. Pattern reconfigurability is obtained by switching the diodes on or off; it encompasses the entire 360° azimuth range. A prototype was fabricated and tested. The numerical and experimental studies are in good agreement. The experimental results indicate that in each of its instantaneous states at GHz, the antenna provides uniform peak realized gains, front-to-back ratios, and radiation efficiencies, respectively, as high as 3.55 dBi, 17.5 dB, and 84.9%, even though it is electrically small: , and low profile: .
Autors: Ming-Chun Tang;Boya Zhou;Richard W. Ziolkowski;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Mar 2017, volume: 65, issue:3, pages: 1063 - 1072
Publisher: IEEE
 
» Low-Rank Covariance-Assisted Downlink Training and Channel Estimation for FDD Massive MIMO Systems
Abstract:
We consider the problem of downlink training and channel estimation in frequency division duplex (FDD) massive MIMO systems, where the base station (BS) equipped with a large number of antennas serves a number of single-antenna users simultaneously. To obtain the channel state information (CSI) at the BS in FDD systems, the downlink channel has to be estimated by users via downlink training and then fed back to the BS. For FDD large-scale MIMO systems, the overhead for downlink training and CSI uplink feedback could be prohibitively high, which presents a significant challenge. In this paper, we study the behavior of the minimum mean-squared error (MMSE) estimator when the channel covariance matrix has a low rank or an approximate low-rank structure. Our theoretical analysis reveals that the amount of training overhead can be substantially reduced by exploiting the low-rank property of the channel covariance matrix. In particular, we show that the MMSE estimator is able to achieve exact channel recovery in the asymptotic low-noise regime, provided that the number of pilot symbols in time is no less than the rank of the channel covariance matrix. We also present an optimal pilot design for the single-user case, and an asymptotic optimal pilot design for the multi-user scenario. Last, we develop a simple model-based scheme to estimate the channel covariance matrix, based on which the MMSE estimator can be employed to estimate the channel. The proposed scheme does not need any additional training overhead. Simulation results are provided to verify our theoretical results and illustrate the effectiveness of the proposed estimated covariance-assisted MMSE estimator.
Autors: Jun Fang;Xingjian Li;Hongbin Li;Feifei Gao;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1935 - 1947
Publisher: IEEE
 
» Low-SNR Capacity of Parallel IM-DD Optical Wireless Channels
Abstract:
The capacity of parallel intensity-modulation and direct-detection optical wireless channels with total average intensity and per-channel peak intensity constraints is studied. The optimal intensity allocation at low signal-to-noise ratio (SNR) is derived, leading to the capacity-achieving ON–OFF keying distribution. Interestingly, while activating the strongest channel is optimal if 1) the peak intensity is fixed, this is not the case if 2) the peak intensity is proportional to the average intensity. The minimum average optical intensity per bit is also studied, and is characterized for case 1) where it is achievable at low SNR. However, in case 2), the average optical intensity per bit grows indefinitely as SNR decreases, indicating that lower optical intensity per bit can be achieved at moderate SNR than low SNR.
Autors: Anas Chaaban;Zouheir Rezki;Mohamed-Slim Alouini;
Appeared in: IEEE Communications Letters
Publication date: Mar 2017, volume: 21, issue:3, pages: 484 - 487
Publisher: IEEE
 
» Low-Temperature Ohmic Contact Formation in AlN/GaN HEMT Using Microwave Annealing
Abstract:
In this brief, a low-temperature microwave annealing (MWA) method is demonstrated for the formation of ohmic contact to AlN/GaN high electron mobility transistors (HEMTs) for the first time. Compared with the traditional rapid thermal annealing (RTA) technique, MWA-HEMT can achieve a comparable low ohmic contact resistance with much smoother surface of ohmic contacts. Transmission electron microscopy results show that no direct current path connecting the 2-D electron gas and the metal is formed. Temperature-dependent contact resistance measurement indicates that field emission tunneling dominates the current transport mechanism in ohmic contact formation. The maximum dc output current density of 1.4 A/mm and the peak extrinsic transconductance () of 270 mS/mm are measured on gate MWA-HEMTs. Besides, MWA-HEMTs have higher ratio due to the lower gate leakage current than that of RTA-HEMTs.
Autors: Lin-Qing Zhang;Zhuo Liu;Sheng-Xun Zhao;Min-Zhi Lin;Peng-Fei Wang;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1385 - 1389
Publisher: IEEE
 
» LU-Based Beamforming Schemes for MIMO Systems
Abstract:
We present a time-domain broadband beamforming based on a unimodular-upper polynomial matrix decomposition. The unimodular factor is the product of elementary - orthogonal matrices and a lower-triangular matrix with 1's on the diagonal, as in the constant matrix lower upper (LU) decomposition. This leads to a - orthogonal LU polynomial matrix decomposition, as a combination of two classical matrix factorization methods: Smith canonical form and LU Gaussian elimination. The inversion of the unimodular factor, for use as a pre/postfilter in the beamforming scheme, is immediate and can be achieved with O(1) complexity. The resulting reduced multiple-input multiple-output (MIMO) channel is exactly diagonal, leading to separate single-input single-output (SISO) channels with no cochannel inteference. There is no need to model the MIMO channel as a Laurent polynomial as usual, thus introducing unnecessary delays just for technical reasons. In addition, it turns out that each of the resulting SISO channels, except to the last channel, reduces to a simple additive noise channel, with no intersymbol interference (ISI), except for unprobable original MIMO channels. However, these very interesting features are to be balanced with the possible noise enhancement in the postfiltering step. The performance in terms of bit error rate (BER) is studied and compared with the QR-based frequency-domain and time-domain broadband beamforming. In particular, the proposed beamforming scheme can be used both in orthogonal frequency-division multiplexing (OFDM) and in single-carrier MIMO systems, without a cyclic prefix (CP). Meanwhile, the QR-based scheme requires a CP extension.
Autors: Moustapha Mbaye;Moussa Diallo;Mamadou Mboup;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Mar 2017, volume: 66, issue:3, pages: 2214 - 2222
Publisher: IEEE
 
» Luminous Properties and Thermal Reliability of Screen-Printed Phosphor-in-Glass-Based White Light-Emitting Diodes
Abstract:
This paper systematically investigates the luminous properties and thermal reliability of phosphor-in-glass (PiG)-based white light-emitting diodes (WLEDs). The PiG was prepared by introducing yellow YAG:Ce3+ phosphor embedded with borosilicate glass through screen-printing and low-temperature sintering. The effects of sintering temperature, phosphor content, and phosphor layer thickness were studied, and then the optimized PiG was achieved. This PiG-based WLED module yields a luminous efficacy (LE) of 114 lm/W, a correlated color temperature of 5524 K, and a color rendering index of 69 at the driving current of 700 mA. Furthermore, after thermal aging test at 200 °C for 500 h, the photoluminescence intensity of PiG is only reduced by 4.3%, which is much lower than the conventional phosphor-in-silicone (PiS) of 26.2%. The LE losses of PiG-based and PiS-based WLED modules are 4.2% and 12.1% after thermal aging of 1000 h at 100 °C, respectively. The aging results show that the proposed PiG exhibits superior thermal stability characteristic, which promises the excellent thermal reliability for PiG-based WLEDs.
Autors: Yang Peng;Ruixin Li;Simin Wang;Zhen Chen;Lei Nie;Mingxiang Chen;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1114 - 1119
Publisher: IEEE
 
» Machine Learning for Noise Sensor Placement and Full-Chip Voltage Emergency Detection
Abstract:
Power supply fluctuation can be potential threat to the correct operations of processors, in the form of voltage emergency that happens when supply voltage drops below a certain threshold. Noise sensors (with either analog or digital outputs) can be placed in the nonfunction area of processors to detect voltage emergencies by monitoring the runtime voltage fluctuations. Our work addresses two important problems related to building a sensor-based voltage emergency detection system: 1) offline sensor placement, i.e., where to place the noise sensors so that the number and locations of sensors are optimized in order to strike a balance between design cost and chip reliability and 2) online voltage emergency detection, i.e., how to use these placed sensors to detect voltage emergencies in the hotspot locations. In this paper, we propose integrated solutions to these two problems, respectively, for analog and digital (more specifically, binary) sensor outputs, by exploiting the voltage correlation between the sensor candidate locations and the hotspot locations. For the analog case, we use the Group Lasso and an ordinary least squares approach; for the binary case, we integrate the Group Lasso and the SVM approach. Experimental results show that, our approach can achieve 2.3X–2.7X better voltage emergency detection results on average for analog outputs when compared to the state-of-the-art work; and for the binary case, on average our methodology can achieve up to 21% improvement in prediction accuracy compared to an approach called max-probability-no-prediction.
Autors: Xiaochen Liu;Shupeng Sun;Xin Li;Haifeng Qian;Pingqiang Zhou;
Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Publication date: Mar 2017, volume: 36, issue:3, pages: 421 - 434
Publisher: IEEE
 
» Magnetic Flux Valve: A Magnetoelectric Materials-Based Device for Conversion and Control of Electric Power
Abstract:
This paper introduces a voltage-controlled static magnetic device called magnetic flux valve. It is mainly used in a magnetic circuit to actively control the magnetic flux through the magnetic circuit. The magnetic flux valve has a laminated structure of two different types of layers made of a magnetostrictive material, e.g., amorphous alloy ribbon, and a piezoelectric material, e.g., piezoelectric sheet. The permeability of the magnetostrictive layers changes when an external control voltage applied to the piezoelectric layers changes, which is known as the converse magnetoelectric effect. A permeability change of the magnetic flux valve will lead to a change of the reluctance of the magnetic flux valve and the reluctance of the magnetic circuit containing the magnetic flux valve. As a consequence, the magnetic flux and/or its distribution in the magnetic circuit will change. There is a great potential to use the proposed magnetic flux valve to develop new equipment, such as tunable inductor and adjustable-voltage-ratio transformer for more flexible conversion and control of electric power in many applications. This paper presents the concept, magnetic properties, working principles, and applications of the magnetic flux valve.
Autors: Haosen Wang;Liyan Qu;Wei Qiao;Bo Liu;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2451 - 2458
Publisher: IEEE
 
» Magnetic Induction-Based Simultaneous Wireless Information and Power Transfer for Single Information and Multiple Power Receivers
Abstract:
Magnetic induction (MI)-based communication systems have gained increased attention in recent years. Typical applications for these systems lie in the area of wireless power transfer, near-field communication (NFC), and wireless sensor networks in challenging environments. In this paper, a system for simultaneous wireless information and power transfer (SWIPT) using MI-based signal transmission is designed for supporting one data stream and multiple parallel power streams. One of the possible applications for this scheme is an NFC-based access point. The overall system is optimized to guarantee a certain quality-of-service for the data stream as well as a maximum sum receive power for all power receivers (max-sum problem) or a maximum receive power for the worst power receiver (max-min problem), respectively. Both optimization problems turn out to be non-convex, such that the optimum solution cannot be found with limited computational complexity. Hence, we provide efficient suboptimal solutions. In this context, a convex approximation of the transmit power constraint in MI-based multiple-input multiple-output systems turns out to be very useful. A very high achievable power efficiency renders the proposed MI-based SWIPT system very promising.
Autors: Steven Kisseleff;Ian F. Akyildiz;Wolfgang H. Gerstacker;
Appeared in: IEEE Transactions on Communications
Publication date: Mar 2017, volume: 65, issue:3, pages: 1396 - 1410
Publisher: IEEE
 
» Maintenance Policies for a Deteriorating System Subject to Non-Self-Announcing Failures
Abstract:
In this study, we comparatively evaluate various maintenance policies for systems subject to continuous-time Markovian deterioration, which may result in non-self-announcing failures. The decision maker inspects the system periodically at the decision epochs, identifies the current state, i.e., good, poor, or failed, and chooses an available action, i.e., do-nothing, repair, or replace. When the system fails, failure will not be detected until the next inspection epoch. The objective is to minimize the expected long-run cost rate, which consists of various components such as inspection, downtime, and maintenance costs. We provide numerical examples to analyze the effect of various cost parameters on the optimum inspection period and policy, and to demonstrate a practical application.
Autors: Büşra Keleş;Salih Tekin;Niyazi Onur Bakır;
Appeared in: IEEE Transactions on Reliability
Publication date: Mar 2017, volume: 66, issue:1, pages: 219 - 232
Publisher: IEEE
 
» Making Sense of the Internet of Things
Abstract:
Welcome to this inaugural department focused on the Internet of Things! Learn how IoT got started, what's ahead, and how IoT News can help you stay on top of emerging developments in this growing field as it moves beyond its visionary promises.
Autors: Florian Michahelles;
Appeared in: IEEE Pervasive Computing
Publication date: Mar 2017, volume: 16, issue:1, pages: 5 - 5
Publisher: IEEE
 
» Manual for Using Homomorphic Encryption for Bioinformatics
Abstract:
Biological data science is an emerging field facing multiple challenges for hosting, sharing, computing on, and interacting with large data sets. Privacy regulations and concerns about the risks of leaking sensitive personal health and genomic data add another layer of complexity to the problem. Recent advances in cryptography over the last five years have yielded a tool, homomorphic encryption, which can be used to encrypt data in such a way that storage can be outsourced to an untrusted cloud, and the data can be computed on in a meaningful way in encrypted form, without access to decryption keys. This paper introduces homomorphic encryption to the bioinformatics community, and presents an informal “manual” for using the Simple Encrypted Arithmetic Library (SEAL), which we have made publicly available for bioinformatic, genomic, and other research purposes.
Autors: Nathan Dowlin;Ran Gilad-Bachrach;Kim Laine;Kristin Lauter;Michael Naehrig;John Wernsing;
Appeared in: Proceedings of the IEEE
Publication date: Mar 2017, volume: 105, issue:3, pages: 552 - 567
Publisher: IEEE
 
» Manufacturing and High Heat Flux Testing of Tungsten-Brazed Mock-Ups for KSTAR Divertor
Abstract:
Development of tungsten brazing technology for the upgraded Korea superconducting tokamak advanced research divertor was launched in early 2013. ITER grade tungsten block was brazed on the CuCrZr alloy in vacuum at 980 °C for 30 min using silver free brazing alloy. An OFHC-copper was used as an interlayer between tungsten and the CuCuZr. The brazing alloy is a 0.05 mm thickness of plate of which component is a Ni–Cu–Mn. It is found that the optimal loading on mock-up is about 20 kPa. Ultrasonic test and shear strength test were carried out to check the strength between tungsten and substrate material. And the joint conditions were analyzed by scanning electron microscopy. Tungsten-brazed mock-ups with a cooling tube were tested at the electron beam facility, Korea heat load test facility-electron beam in Korea Atomic Energy Research Institute. The high heat flux test was performed for tungsten-brazed mock-ups under heat flux of about 5 MW/ with more than 2000 cycles. All the tungsten-brazed mock-ups met the requirements and there was no delamination or failure at the bonding joints.
Autors: K. M. Kim;H. T. Kim;J. H. Song;H. K. Kim;S. H. Park;S. H. Hong;B. C. Kim;H. L. Yang;Y. S. Kim;S. Y. You;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Mar 2017, volume: 45, issue:3, pages: 519 - 522
Publisher: IEEE
 
» MARCOnI—ConvNet-Based MARker-Less Motion Capture in Outdoor and Indoor Scenes
Abstract:
Marker-less motion capture has seen great progress, but most state-of-the-art approaches fail to reliably track articulated human body motion with a very low number of cameras, let alone when applied in outdoor scenes with general background. In this paper, we propose a method for accurate marker-less capture of articulated skeleton motion of several subjects in general scenes, indoors and outdoors, even from input filmed with as few as two cameras. The new algorithm combines the strengths of a discriminative image-based joint detection method with a model-based generative motion tracking algorithm through an unified pose optimization energy. The discriminative part-based pose detection method is implemented using Convolutional Networks (ConvNet) and estimates unary potentials for each joint of a kinematic skeleton model. These unary potentials serve as the basis of a probabilistic extraction of pose constraints for tracking by using weighted sampling from a pose posterior that is guided by the model. In the final energy, we combine these constraints with an appearance-based model-to-image similarity term. Poses can be computed very efficiently using iterative local optimization, since joint detection with a trained ConvNet is fast, and since our formulation yields a combined pose estimation energy with analytic derivatives. In combination, this enables to track full articulated joint angles at state-of-the-art accuracy and temporal stability with a very low number of cameras. Our method is efficient and lends itself to implementation on parallel computing hardware, such as GPUs. We test our method extensively and show its advantages over related work on many indoor and outdoor data sets captured by ourselves, as well as data sets made available to the community by other research labs. The availability of good evaluation data sets is paramount for scientific progress, and many existing test data sets focus on controlled indoor settings, do not feature much variety - n the scenes, and often lack a large corpus of data with ground truth annotation. We therefore further contribute with a new extensive test data set called MPI-MARCOnI for indoor and outdoor marker-less motion capture that features scenes of varying complexity and varying camera count, and that features ground truth reference data from different modalities, ranging from manual joint annotations to marker-based motion capture results. Our new method is tested on these data, and the data set will be made available to the community.
Autors: A. Elhayek;E. de Aguiar;A. Jain;J. Thompson;L. Pishchulin;M. Andriluka;C. Bregler;B. Schiele;C. Theobalt;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Mar 2017, volume: 39, issue:3, pages: 501 - 514
Publisher: IEEE
 
» Marine Duty Harmonic Mitigation on DC Propulsion Saves Oil Service Vessel Program
Abstract:
An offshore oil and gas service vessel equipped with dc propulsion drives retrofitted with revenue generating equipment, such as remote operated vehicles (ROV) and cranes, could not pass sea trials due to multiple failures (including loss of navigation) caused by harmonic distortion. Marine propulsion systems represent a dominant load on most vessels and dynamically positioned (DP) offshore installations. These propulsion systems are typically nonlinear in nature with very high harmonic injection, which can have a significant impact on vessel wide systems and subsystems. AC adjustable speed drive (ASD) propulsion systems characteristically inject current harmonics into the generator system impedance creating voltage distortion. DC ASDs produce even higher voltage distortion levels due to voltage notching caused by the thyristor firing which makes their harmonic mitigation requirement much more challenging. In order to eliminate the numerous harmonic problems, the dc propulsion system of the oil service vessel was retrofitted with harmonic mitigation equipment. The case study discusses: 1) operational issues including component failures in crane controls and ROV equipment while operating in DP mode; 2) field testing to document the harmonic distortion conditions created by the propulsion and thruster dc ASDs prior to treatment; 3) computer simulation of the dc drive propulsion system to determine a harmonic mitigation strategy; and 4) extensive sea trial testing of the power system with harmonic mitigation to demonstrate compliance with ABS harmonic limits, compatibility of the harmonic mitigation with the ASD equipment, and resolution of all connected equipment failures and operational problems.
Autors: Marek Farbis;Anthony Hoevenaars;Michael McGraw;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1617 - 1626
Publisher: IEEE
 
» Massive Internet of Things for Industrial Applications: Addressing Wireless IIoT Connectivity Challenges and Ecosystem Fragmentation
Abstract:
This article provides an overview of the development and standardizations of connectivity solutions for enabling the Industrial Internet of Things (IIoT). It also highlights key IIoT connectivity technologies and platforms that have the potential of driving the next industrial revolution. In addition, the article addresses the main challenges standing in the way of realizing the full potential of the IIoT, namely attaining secure connectivity and managing a vastly fragmented ecosystem of connectivity solutions and platforms. Finally, IIoT connectivity challenges are illustrated by the example of future building automation.
Autors: Shahid Mumtaz;Ahmed Alsohaily;Zhibo Pang;Ammar Rayes;Kim Fung Tsang;Jonathan Rodriguez;
Appeared in: IEEE Industrial Electronics Magazine
Publication date: Mar 2017, volume: 11, issue:1, pages: 28 - 33
Publisher: IEEE
 
» Maximizing Data Rate for Multiway Relay Channels With Pairwise Transmission Strategy
Abstract:
In a multiway relay channel (MWRC), pairwise transmission strategy can be used to reduce the computational complexity at the relay and the users without sacrificing the data rate significantly. The performance of such pairwise strategies, however, is affected by the way that the users are paired to transmit. In this paper, we study the effect of pairing on the common rate and sum rate of an MWRC with functional-decode-forward (FDF) relaying strategy where users experience asymmetric channel conditions. To this end, we first develop a graphical model for an MWRC with pairwise transmission strategy. Using this model, we then find the maximum achievable common rate and sum rate as well as the user pairings that achieve these rates. This marks the ultimate performance of FDF relaying in an MWRC setup. Further, we show that the rate enhancement achieved through the optimal user pairing becomes less pronounced at higher signal to noise ratios. Using computer simulations, the performance of the optimal pairing is compared with those of other proposed pairings in the literature.
Autors: Reza Rafie Borujeny;Moslem Noori;Masoud Ardakani;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1609 - 1618
Publisher: IEEE
 
» Maximum Entropy Kernels for System Identification
Abstract:
Bayesian nonparametric approaches have been recently introduced in system identification scenario where the impulse response is modeled as the realization of a zero-mean Gaussian process whose covariance (kernel) has to be estimated from data. In this scheme, quality of the estimates crucially depends on the parametrization of the covariance of the Gaussian process. A family of kernels that have been shown to be particularly effective in the system identification framework is the family of Diagonal/Correlated (DC) kernels. Maximum entropy properties of a related family of kernels, the Tuned/Correlated (TC) kernels, have been recently pointed out in the literature. In this technical note, we show that maximum entropy properties indeed extend to the whole family of DC kernels. The maximum entropy interpretation can be exploited in conjunction with results on matrix completion problems in the graphical models literature to shed light on the structure of the DC kernel. In particular, we prove that the DC kernel admits a closed-form factorization, inverse, and determinant. These results can be exploited both to improve the numerical stability and to reduce the computational complexity associated with the computation of the DC estimator.
Autors: Francesca Paola Carli;Tianshi Chen;Lennart Ljung;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Mar 2017, volume: 62, issue:3, pages: 1471 - 1477
Publisher: IEEE
 
» Measurement of Breath Frequency by Body-Worn UWB Radars: A Comparison Among Different Signal Processing Techniques
Abstract:
In this paper, different signal processing techniques are used to evaluate the breath frequency of volunteers starting from signals measured by a body-worn ultra-wideband radar. The measurement setup is based on a time domain reflectometry technique, and comprises an ultra-wideband antenna in contact with the subject’s thorax, and a vector network analyzer. The breath frequencies, obtained applying the different processing techniques on the signal reflected from the human thorax, are compared in terms of accuracy against measures acquired by a piezoelectric belt, which is a widely adopted commercial system for respiratory activity monitoring. Finally, the different techniques are compared with each other in terms of accuracy and execution time.
Autors: Erika Pittella;Blerina Zanaj;Stefano Pisa;Marta Cavagnaro;
Appeared in: IEEE Sensors Journal
Publication date: Mar 2017, volume: 17, issue:6, pages: 1772 - 1780
Publisher: IEEE
 
» Measurement of Charge Distributions in a Bubbling Fluidized Bed Using Wire-Mesh Electrostatic Sensors
Abstract:
In order to maintain safe and efficient operation of a fluidized bed, the electrostatic charges in the bed should be monitored continuously. Electrostatic sensors with wire-mesh electrodes are introduced in this paper to measure the charge distribution in the cross section of a fluidized bed. A finite element model is built to investigate the sensing characteristics of the wire-mesh sensors. In comparison with conventional electrostatic sensors, wire-mesh sensors have higher and more uniform sensitivity distribution. Based on the induced charges on the electrodes and the sensitivity distributions of the sensors, the charge distribution in the cross section of the fluidized bed is reconstructed. However, it is difficult to directly measure the induced charges on the electrodes. A charge calibration process is conducted to establish the relationship between the induced charge on the electrode and the electrostatic signal. Experimental studies of charge distribution measurement were conducted on a lab-scale bubbling fluidized bed. The electrostatic signals from the wire-mesh sensors in the dense phase and splash regions of the bed for different fluidization air flow rates were obtained. Based on the results obtained from the charge calibration process, the estimated induced charges on the electrodes are calculated from the root-mean-square values of the electrostatic signals. The characteristics of the induced charges on the electrodes and the charge distribution in the cross section under different flow conditions are investigated, which proves that wire-mesh electrostatic sensors are able to measure the charge distribution in the bubbling fluidized bed.
Autors: Wenbiao Zhang;Yong Yan;Xiangchen Qian;Yanjun Guan;Kai Zhang;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Mar 2017, volume: 66, issue:3, pages: 522 - 534
Publisher: IEEE
 
» Measurement of Ion Mach Number of Arcjet Plasmas by a Directional Langmuir Probe Under High-Gas Pressure
Abstract:
Spatial profile of an ion Mach number for arcjet He and Ar plasmas are measured by using a directional Langmuir probe. The Ar arcjet has bright–dark emission structures, implying that expansion–compression waves are formed, whereas no structure is observed for the He discharge. It is found that for He plasma, the Mach number monotonically decreases along the jet axis, while in the Ar jet the prominent peaks appear. The peak positions are almost the same with the bright emission regions, indicating that there is a strong correlation between the plasma emission structure and the Mach number.
Autors: Wataru Sasano;Taiichi Shikama;Kazuki Kozue;Leo Matsuoka;Naoki Tamura;Shinichi Namba;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Mar 2017, volume: 45, issue:3, pages: 485 - 488
Publisher: IEEE
 
» Measurement of the Band-to-Band Registration of the SNPP VIIRS Imaging System From On-Orbit Data
Abstract:
The visible infrared imaging radiometer suite (VIIRS) instrument onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite was launched on October 28, 2011. The VIIRS instrument is a whiskbroom system with 22 spectral and thermal bands split between 16 moderate resolution bands (M-bands), 5 imagery resolution bands (I-bands), and a day–night band. In this study, we measure the along-scan and along-track band-to-band registration between the I-bands and M-bands from on-orbit data. This measurement is performed by computing the normalized mutual information (NMI) between shifted image band pairs and finding the amount of shift required (if any) to produce the peak in NMI value. Subpixel accuracy is obtained by utilizing a bicubic interpolation. The product of the NMI peak slope and the NMI peak value is shown to be a better criterion for evaluating the quality of the NMI result than just the NMI peak value. Registration shifts are found to be similar to prelaunch measurements and stable (within measurement error) over the instrument's first four years in an orbit.
Autors: James C. Tilton;Guoqing Lin;Bin Tan;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Mar 2017, volume: 10, issue:3, pages: 1056 - 1067
Publisher: IEEE
 
» Measurement of Three-Dimensional Magnetic Properties With Feedback Control and Harmonic Compensation
Abstract:
Three-dimensional (3-D) magnetic fluxes exist in rotating electric machines and T-joints of three-phase power transformers, and may cause local overheating in these devices. In this paper, 3-D magnetic properties of the core materials are measured by an improved 3-D magnetic property tester. First, the 3-D magnetization system is modeled by the voltage and flux linkage equations. Their parameters including the self and mutual inductances and nonlinear impedance are analyzed by the finite element analysis and measured by experiments. Second, a magnetic feedback method in the frequency domain is proposed to obtain the desired magnetization loci. Third, when the specimen is in deep magnetic saturation, the harmonics of magnetic flux density waveform would affect the shape of the corresponding magnetic field strength loci and the accuracy of loss computation. Thus, a waveform compensation method is proposed to eliminate the effects of harmonics. Fourth, the tensor effects of H coils are eliminated by averaging the results of clockwise and counterclockwise rotational experiments. Finally, the 3-D magnetic test system with feedback control, harmonics compensation, and automated data processing is developed. By using the 3-D magnetic tester, samples of nonoriented silicon sheet steel are measured with various excitation models and the results are more reliable than those obtained by experiments without feedback and harmonics compensation.
Autors: Changgeng Zhang;Yongjian Li;Jingsong Li;Qingxin Yang;Jianguo Zhu;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2476 - 2485
Publisher: IEEE
 
» Measurements of high voltage DC fields in air
Abstract:
The global demand for electric power continues to increase in most countries but in particular in non-OECD (Organisation for Economic Cooperation and Development) countries [1]. Often the generation is located far from the consumers, and this requires transmission of electric power over long distances. For various reasons, high voltage direct current (HVDC) is often the preferred technology for these links [2]. To keep losses at a minimum, the voltage must be as high as possible, and this has stimulated the development of ultra-high voltage DC transmission. Over the last decade, 800 kV has been established as a new standard level for long transmission links [3].
Autors: Birgitta Källstrand;Kenneth Johansson;Lars Walfridsson;Daniel Borg;Charles Doiron;Markus Saltzer;David Emilsson;
Appeared in: IEEE Electrical Insulation Magazine
Publication date: Mar 2017, volume: 33, issue:2, pages: 24 - 34
Publisher: IEEE
 
» Mechanical Torque Ripple From a Passive Diode Rectifier in a 12 kW Vertical Axis Wind Turbine
Abstract:
The influence of passive rectification on the mechanical torque of a permanent magnet generator for a directly driven vertical axis wind turbine has been studied. Passive diode rectification introduce electromagnetic torque ripple from the generator. The conversion of electromagnetic torque ripple into mechanical torque ripple and rotational speed ripple has been modeled, analytically evaluated, and simulated. The simulations have been compared to measurements on an open site 12 kW prototype. A parameter study with the model illustrates the impact of shaft torsional spring constant, generator rotor inertia, generator inductance, and dc-link capacitance. The results show that the shaft and generator rotor can be an effective filter of electromagnetic torque ripple from diode rectification. The measured mechanical torque ripple amplitude on the prototype is less than 0.9% of nominal turbine torque. The measurements compare well with the simulations.
Autors: Morgan Rossander;Anders Goude;Sandra Eriksson;
Appeared in: IEEE Transactions on Energy Conversion
Publication date: Mar 2017, volume: 32, issue:1, pages: 164 - 171
Publisher: IEEE
 
» Mechanism of Depletion-Mode TDDB for 4H-SiC MOS Structure
Abstract:
The depletion-mode time-dependent dielectric breakdown (DM-TDDB) mechanism was investigated with n-type 4H-SiC MOS capacitors depleted by high-voltage dc bias. Under the DM-TDDB stress, the hole generation beneath the oxide/SiC interface and its injection into the oxide appeared in the current measurement results. The lifetime distribution was clearly divided into two groups: shorter and longer time to breakdown (). The breakdown point for the shorter was located close to a threading dislocation (TD) of the 4H-SiC, whereas the capacitors for the longer contained no dislocation. For the longer , the charge-to-breakdown () decreased from approximately 4.5 to 0.1 C/cm with an increase in the electric potential drop () below the interface at 503 K, demonstrating that the high-energy-hole injection lowers the lifetime. For the shorter , the TD was presumed to induce the additional hot-hole injection from the deeper depletion region into the local oxide and thereby precipitate the percolation path formation.
Autors: Tomokatsu Watanabe;Shiro Hino;Toshiaki Iwamatsu;Shingo Tomohisa;Satoshi Yamakawa;
Appeared in: IEEE Transactions on Device and Materials Reliability
Publication date: Mar 2017, volume: 17, issue:1, pages: 163 - 169
Publisher: IEEE
 
» Medium Access for Concurrent Traffic in Wireless Body Area Networks: Protocol Design and Analysis
Abstract:
Wireless body area networks have been deployed to monitor the health condition of patients. In these applications, multiple sensors are required to report real-time data to the sink such that a physician can diagnose accurately, particularly for intensive care patients, which boosts the convergecast traffic load and increases the collision probability. However, the existing protocols cannot effectively operate under such concurrent traffic load. To bridge this gap, we present a novel two-phase receiver-initiated medium access control (MAC) protocol for concurrent traffic based on asynchronous duty cycling, which is called C-MAC. Technically, C-MAC in the first phase employs carrier-sense multiple access with collision avoidance of the IEEE 802.15.6 standard and designs an ordering-based communication algorithm to effectively avoid collisions. Moreover, C-MAC enables sensor nodes to switch to standby mode to avoid idle listening and overhearing in the second phase. Furthermore, theoretically, we explicitly formulate the mathematical expressions of the random delay and energy consumption of C-MAC. Finally, we conduct extensive numerical analysis and simulation to demonstrate the correctness of theoretical results and the better effectiveness and efficiency of C-MAC than that of RI-MAC and A-MAC in terms of transmission delay and energy consumption.
Autors: Rongrong Zhang;Hassine Moungla;Jihong Yu;Ahmed Mehaoua;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Mar 2017, volume: 66, issue:3, pages: 2586 - 2599
Publisher: IEEE
 
» Meetings calendar
Abstract:
Provides a listing of future meetings.
Autors: Davide Fabiani;
Appeared in: IEEE Electrical Insulation Magazine
Publication date: Mar 2017, volume: 33, issue:2, pages: 69 - 71
Publisher: IEEE
 
» Melanoma Classification on Dermoscopy Images Using a Neural Network Ensemble Model
Abstract:
We develop a novel method for classifying melanocytic tumors as benign or malignant by the analysis of digital dermoscopy images. The algorithm follows three steps: first, lesions are extracted using a self-generating neural network (SGNN); second, features descriptive of tumor color, texture and border are extracted; and third, lesion objects are classified using a classifier based on a neural network ensemble model. In clinical situations, lesions occur that are too large to be entirely contained within the dermoscopy image. To deal with this difficult presentation, new border features are proposed, which are able to effectively characterize border irregularities on both complete lesions and incomplete lesions. In our model, a network ensemble classifier is designed that combines back propagation (BP) neural networks with fuzzy neural networks to achieve improved performance. Experiments are carried out on two diverse dermoscopy databases that include images of both the xanthous and caucasian races. The results show that classification accuracy is greatly enhanced by the use of the new border features and the proposed classifier model.
Autors: Fengying Xie;Haidi Fan;Yang Li;Zhiguo Jiang;Rusong Meng;Alan Bovik;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Mar 2017, volume: 36, issue:3, pages: 849 - 858
Publisher: IEEE
 
» Mercury Reduction—The Plant Experience
Abstract:
This paper communicates the design and installation process of a mercury capture system in a cement kiln located in the state of Oregon. This paper will document the timeline and decision points between 2006 and 2012 pertinent to the reduction of mercury, first to meet a state agreement and later to meet new federal government requirements. The use of powder-activated carbon as a collection medium will be discussed, along with various materials tested with less positive results. The optimization of the system to increase performance will be covered, along with methods of mercury measurement and tracking employed for reporting. This paper will show that the subject cement plant overcame a significant challenge to install a system capable of bringing emissions in compliance with the Environmental Protection Agency Portland Cement National Emissions Standard for Hazardous Air Pollutants limit.
Autors: Terry Kerby;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1569 - 1575
Publisher: IEEE
 
» Message from the APMRC 2016 Publication Chairs
Abstract:
It was our great honor and pleasure to host the Asia-Pacific Magnetic Recording Conference (APMRC) at Yonsei University, Seoul, South Korea, from July 13–15, 2016. All members of the international scientific community interested in new developments in magnetic recording technologies were invited to attend. Among other topics the Conference addressed issues related to ultrahigh-density recording in the multi-terabits-per-square-inch regime.
Autors: Kyoung-Su Park;Zhang Qide;
Appeared in: IEEE Transactions on Magnetics
Publication date: Mar 2017, volume: 53, issue:3, pages: 1 - 1
Publisher: IEEE
 
» Message From the Editor-In-Chief
Abstract:
Autors: FABRIZIO LOMBARDI;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Mar 2017, volume: 16, issue:2, pages: 159 - 159
Publisher: IEEE
 
» Message From the Incoming Editor-in-Chief
Abstract:
Presents the introductory editorial for this issue of the publication.
Autors: WENWU ZHU;
Appeared in: IEEE Transactions on Multimedia
Publication date: Mar 2017, volume: 19, issue:3, pages: 446 - 446
Publisher: IEEE
 
» Message From the Outgoing Editor-in-Chief
Abstract:
Presents the introductory editorial for this issue of the publication.
Autors: CHANG WEN CHEN;
Appeared in: IEEE Transactions on Multimedia
Publication date: Mar 2017, volume: 19, issue:3, pages: 445 - 445
Publisher: IEEE
 
» Message-Passing Receiver for OFDM Systems Over Highly Delay-Dispersive Channels
Abstract:
Propagation channels with maximum excess delay exceeding the duration of the cyclic prefix (CP) in OFDM systems cause intercarrier and intersymbol interference which, unless accounted for, degrade the receiver performance. Using tools from Bayesian inference and sparse signal reconstruction, we derive an iterative algorithm that estimates an approximate representation of the channel impulse response and the noise variance, estimates and cancels the intrinsic interference and decodes the data over a block of symbols. Simulation results show that the receiver employing our algorithm outperforms receivers applying traditional interference cancellation and pilot-based schemes, and it approaches the performance of an ideal receiver with perfect channel state information and perfect interference cancellation capabilities. We highlight the relevance of our algorithm in the context of both current and future wireless communications systems. By enabling the OFDM receiver experiencing these harsh conditions to locally cancel the interference, our design circumvents the spectral efficiency loss incurred by extending the CP duration, otherwise a straightforward solution. Furthermore, it sets the premises for the development of receivers for multicarrier systems like 5G, in which the subcarrier orthogonality may be relaxed or the frame duration shortened, at the expense of cutting down the CP or even removing it altogether.
Autors: Oana-Elena Barbu;Carles Navarro Manchón;Christian Rom;Bernard H. Fleury;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1564 - 1578
Publisher: IEEE
 
» Metal-Free Fully Solution-Processable Flexible Electrolyte-Gated Carbon Nanotube Field Effect Transistor
Abstract:
Carbon nanotube-based field effect transistors (CNTFETs) are an interesting alternative to organic FETs in the growing field of printed electronics. Solution processed CNTFETs can be fabricated at low temperatures, are compatible with roll to roll processes and with flexible substrates. Usually metal electrodes for CNTFETs are deposited using standard techniques (e.g., evaporation or sputtering) which require expensive equipment and a high thermal budget. The elimination of such deposition step would allow a fully solution-based process for the CNTFETs fabrication. In this paper, we demonstrate an all carbon nanotube (CNT) transistor which is entirely solution processable without sacrificing the device performance. Performed detailed contact resistance analysis shows that CNT electrodes make better contacts to semiconducting CNTs channel than gold electrodes. The device performance is shown for an electrolyte-gated CNTFET fabricated on a flexible substrate. Such transistors are used as low cost biosensors for vivo implants by exploiting better interaction of flexible substrates to cells.
Autors: Vijay Deep Bhatt;Saumya Joshi;Paolo Lugli;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1375 - 1379
Publisher: IEEE
 
» Methodology for Rotor Angle Transient Stability Assessment in Parameter Space
Abstract:
In this paper, an efficient methodology to assess rotor angle stability (RAS) in parameter space has been proposed. This methodology maps deformations of the power system RAS region under operational changes to a security region in parameter space that can be assessed online. In order to choose the proper parametrization, security boundaries have been constructed using polynomial regression models with coefficients obtained from ordinary least squares. The identification of suitable parametrization has been carried out, and the newly introduced sensitivity of a single machine equivalent (SIME) has been employed to describe the behavior of a power system along different parameter-space directions. For the chosen parametrization, constrained least squares optimization set up as a quadratic programming problem has been used in order to keep the estimates inside the security region. The case study has been carried out using small test systems in two- and three-dimensional parameter-spaces.
Autors: Marina Oluic;Mehrdad Ghandhari;Bertil Berggren;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1202 - 1211
Publisher: IEEE
 
» Metric Similarity Joins Using MapReduce
Abstract:
Given two object sets Q and O, a metric similarity join finds similar object pairs according to a certain criterion. This operation has a wide variety of applications in data cleaning and data mining, to name but a few. However, the rapidly growing volume of data nowadays challenges traditional metric similarity join methods, and thus, a distributed method is required. In this paper, we adopt a popular distributed framework, namely, MapReduce, to support scalable metric similarity joins. To ensure the load balancing, we present two sampling based partition methods. One utilizes the pivot and the space-filling curve mappings to cluster the data into one-dimensional space, and then selects high quality centroids to enable equal-sized partitions. The other uses the KD-tree partitioning technique to equally divide the data after the pivot mapping. To avoid unnecessary object pair evaluation, we propose a framework that maps the two involved object sets in order, where the range-object filtering, the double-pivot filtering, the pivot filtering, and the plane sweeping techniques are utilized for pruning. Extensive experiments with both real and synthetic data sets demonstrate that our solutions outperform significantly existing state-of-the-art competitors.
Autors: Gang Chen;Keyu Yang;Lu Chen;Yunjun Gao;Baihua Zheng;Chun Chen;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Mar 2017, volume: 29, issue:3, pages: 656 - 669
Publisher: IEEE
 
» Microbubble Composition and Preparation for High-Frequency Contrast-Enhanced Ultrasound Imaging: In Vitro and In Vivo Evaluation
Abstract:
Although high-frequency ultrasound imaging is gaining attention in various applications, hardly any ultrasound contrast agents (UCAs) dedicated to such frequencies (>15 MHz) are available for contrast-enhanced ultrasound (CEUS) imaging. Moreover, the composition of the limited commercially available UCAs for high-frequency CEUS (hfCEUS) is largely unknown, while shell properties have been shown to be an important factor for their performance. The aim of our study was to produce UCAs in-house for hfCEUS. Twelve different UCA formulations A-L were made by either sonication or mechanical agitation. The gas core consisted of C4F10 and the main coating lipid was either 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC; A-F formulation) or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC; G-L formulation). Mechanical agitation resulted in UCAs with smaller microbubbles (number weighted mean diameter ~1 ) than sonication (number weighted mean diameter ~2 ). UCA formulations with similar size distributions but different main lipid components showed that the DPPC-based UCA formulations had higher nonlinear responses at both the fundamental and subharmonic frequencies in vitro for hfCEUS using the Vevo2100 high-frequency preclinical scanner (FUJIFILM VisualSonics, Inc.). In addition, UCA formulations F (DSPC-based) and L (DPPC-based) that were made by mechanical agitation performed similar in vitro to the commercially available Target-Ready MicroMarker (FUJIFILM VisualSonics, Inc.). UCA formulation F also performed similar to Target-Ready MicroMarker in vivo in pigs with similar mean contrast intensity within the kidney (), - ut formulation L did not. This is likely due to the lower stability of formulation L in vivo. Our study shows that DSPC-based microbubbles produced by mechanical agitation resulted in small microbubbles with high nonlinear responses suitable for hfCEUS imaging.
Autors: Verya Daeichin;Tom van Rooij;Ilya Skachkov;Bulent Ergin;Patricia A. C. Specht;Alexandre Lima;Can Ince;Johan G. Bosch;Antonius F. W. van der Steen;Nico de Jong;Klazina Kooiman;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Mar 2017, volume: 64, issue:3, pages: 555 - 567
Publisher: IEEE
 
» Microelectronic Circuits: Analysis and Design, Third Edition [Book News]
Abstract:
The third edition of Microelectronic Circuits: Analysis and Design is a completely reorganized book using a top-down approach followed by the usual bottom-up approach. The objectives are twofold: 1) to study semiconductor devices, and 2) to develop students' skills in the analysis and design of analog and digital electronic circuits.
Autors: Fernando A. Silva;
Appeared in: IEEE Industrial Electronics Magazine
Publication date: Mar 2017, volume: 11, issue:1, pages: 85 - 85
Publisher: IEEE
 
» Microfluidic Probes and Quadrupoles: A new era of open microfluidics
Abstract:
The microfluidic probe (MFP) is a noncontact technology that applies the concept of hydrodynamic flow confinement (HFC) within a small gap to eliminate the need for closed microfluidic conduits and, therefore, overcome the conventional closed-system microfluidic limitation. Since its invention, the concept has experienced continuing advancement with several applications, ranging from manipulating mammalian cells and printing protein arrays to performing microfabrication.
Autors: Ayoola T. Brimmo;Mohammad A. Qasaimeh;
Appeared in: IEEE Nanotechnology Magazine
Publication date: Mar 2017, volume: 11, issue:1, pages: 20 - 31
Publisher: IEEE
 
» Microscopic Hot-Carrier Degradation Modeling of SiGe HBTs Under Stress Conditions Close to the SOA Limit
Abstract:
We present and validate a physics-based model to describe the underlying mechanisms of hot-carrier degradation in bipolar transistors. Our analysis is based on a deterministic solution of the coupled system of Boltzmann transport equations for electrons and holes. The full-band transport model provides the energy distribution functions of the charge carriers interacting with the passivated Si–H bonds along the oxide interface. The simulation results assert the dominant role of hot holes along the emitter–base spacer oxide interface in the long-term degradation of an n-p-n SiGe heterojunction bipolar transistor under low and high-current conditions at the border of the safe-operating area. The interface trap density is calculated by incorporating an energy driven paradigm for the microscopicmechanisms of defect creation into a reaction-limitedmodelwith dispersive reaction rates. These interface traps increase the forward-mode base current via Shockley–Read–Hall recombination and degrade the overall device performance. The Gummel characteristics of a degraded device and time evolution of the excess base current for different stress conditions are verified versus the experimental data obtained for a state-of-the-art toward-terahertz SiGe HBT.
Autors: Hamed Kamrani;Dominic Jabs;Vincenzo d’Alessandro;Niccolò Rinaldi;Thomas Jacquet;Cristell Maneux;Thomas Zimmer;Klaus Aufinger;Christoph Jungemann;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 923 - 929
Publisher: IEEE
 
» Microwave Imaging Using Normal Electric-Field Components Inside Metallic Resonant Chambers
Abstract:
A novel 3-D microwave imaging approach performed within a resonant air-filled metallic chamber is introduced and investigated. The new method utilizes the measurements of normal electric-field components at discrete points along the metallic chamber’s wall—near the chamber-wall boundary, the normal-field components are dominant, while the tangential components vanish. The inversion algorithm fully incorporates the resonant features of the low-loss chamber. A numerical study is used to quantify the imaging performance of using this technique compared with the traditional unbounded domain imaging. An experimental system is presented where the electric field is collected using 24 antennas distributed in three circumferential layers around an object of interest located inside the circular-cylindrical metallic chamber. For collecting the normal component of the field, two types of linearly polarized antennas are investigated: monopole antennas and specially designed reconfigurable antennas (RAs), both projecting perpendicularly out from the chamber walls into the enclosure. The measured data are calibrated and then inverted using a multiplicatively regularized finite-element contrast source inversion algorithm. Using 3-D reconstructions of simple dielectric targets, it is shown that utilizing the RAs improves imaging performance due to a reduction in the modeling error introduced in the inversion algorithm.
Autors: Mohammad Asefi;Amer Zakaria;Joe LoVetri;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Mar 2017, volume: 65, issue:3, pages: 923 - 933
Publisher: IEEE
 
» Mid-Level Feature Representation via Sparse Autoencoder for Remotely Sensed Scene Classification
Abstract:
Feature representation is a classic problem in the machine learning community due to the fact that different representations can entangle and hide more or less the different explanatory factors of variation behind the raw data. Especially for scene classification, its performance generally depends on the discriminative power of feature representation. Recently, unsupervised feature learning attracts tremendous attention because of its ability to learn feature representation automatically. However, reliable performance of feature representations by unsupervised learning always requires a large number of features and complex framework of mid-level feature representation. To alleviate such drawbacks, this paper presents a new framework of mid-level feature representation, which does not need learn many convolutional features during the unsupervised feature learning process, and has few parameter settings. In detail, the unsupervised feature learning method, sparse autoencoder, is employed to learn relatively small number of convolutional features from input dataset, and then extended features are extracted from the learned features by a multiple normalized difference features extraction method to compose a derivative feature set. At mid-level feature representation stage, in order to avoid poor performance of standard pooling technology in solving problems brought by rotation and translation of scene images, global feature descriptors (histogram moments, mean, variance, standard deviation) are utilized to build mid-level feature representations of images. For validation and comparison purposes, the proposed approach is evaluated via experiments with two challenging high-resolution remote sensing datasets. The results demonstrate that the approach is effective, and shows strong performance for remotely sensed scene classification.
Autors: Erzhu Li;Peijun Du;Alim Samat;Yaping Meng;Meiqin Che;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Mar 2017, volume: 10, issue:3, pages: 1068 - 1081
Publisher: IEEE
 
» Military Applications of Invasive Brain Stimulation [Industry Viewpoint]
Abstract:
Autors: Melanie Segado;
Appeared in: IEEE Technology and Society Magazine
Publication date: Mar 2017, volume: 36, issue:1, pages: 13 - 15
Publisher: IEEE
 
» Military Insertables: Lessons from Civilian Use
Abstract:
Digital devices, once large enough to fill a room, are now small enough to be inserted into the human body. Even mobile devices have shrunk from large luggables, which were heavy and difficult to carry, to wearables that can effortlessly be worn on a person. A possible next step is insertables - digital devices that go in, through, or underneath the skin [1]. We use the term insertables to specifically categorize devices that are voluntarily chosen, minimally invasive, and relatively easy to insert and remove.
Autors: Kayla J. Heffernan;Frank Vetere;Shanton Chang;
Appeared in: IEEE Technology and Society Magazine
Publication date: Mar 2017, volume: 36, issue:1, pages: 58 - 61
Publisher: IEEE
 
» Millimeter-Wave Secrecy Beamforming Designs for Two-Way Amplify-and-Forward MIMO Relaying Networks
Abstract:
The gigahertz unlicensed bandwidth spectrum endows millimeter-wave (mmWave) communications with the great potential of realizing high data transmission rates. Similar to all wireless transmission technologies, mmWave communications are also susceptible to security threats. This problem becomes more serious for cooperative networks that need more information exchanges. In this paper, we investigate the secrecy beamforming designs for mmWave two-way amplify-and-forward (AF) multiple-input–multiple-output (MIMO) relaying networks. To control hardware size and cost, an additional rank constraint is posed on the forwarding matrix at the relay to control the number of analog-to-digital converters (ADCs). In general, the considered optimization problem is nonconvex and very challenging. Based on iterative optimization algorithms, the secrecy beamforming designs are successfully decoupled into a series of convex subproblems that can be solved efficiently. Finally, numerical experiments are conducted to demonstrate the performance advantages of the proposed secrecy beamforming designs.
Autors: Shiqi Gong;Chengwen Xing;Zesong Fei;Shaodan Ma;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Mar 2017, volume: 66, issue:3, pages: 2059 - 2071
Publisher: IEEE
 
» Millimeter-Wave Wireless Channel Control Using Spatially Adaptive Antenna Arrays
Abstract:
A wireless channel control concept based on spatially, i.e., position adaptive antenna arrays is introduced. This technique simultaneously utilizes beam-steering and spatial adaptation to enhance the wireless channel gain and system capacity. The concept is inspired by the microfluidically reconfigurable RF devices as they can enable compact systems with spatial adaptation capability. Specifically, a five element linear 28 GHz mm-wave antenna array design that can achieve beam-steering via phase shifters and spatial adaptation via microfluidics is detailed. Simulated realized gain patterns at various array positions and phase shifter states are subsequently utilized in link and system level simulations to demonstrate the advantages of the proposed concept. It is shown that a wireless communications system can achieve 51% improvement in the mean signal-to-interference ratio due to the spatial adaptation capability.
Autors: Mustafa Harun Yılmaz;Ertugrul Güvenkaya;Gökhan Mumcu;Hüseyin Arslan;
Appeared in: IEEE Communications Letters
Publication date: Mar 2017, volume: 21, issue:3, pages: 680 - 683
Publisher: IEEE
 
» MIMO Subband Volterra Digital Predistortion for Concurrent Aggregated Carrier Communications
Abstract:
This paper presents a multiple-input multiple-output (MIMO) nonlinear mitigation technique for closely spaced concurrent aggregated carrier systems. The transmitter architecture considers band-limited sources, where the predistorter and signal bandwidth are the same, thus reducing transmitter hardware cost and power consumption. The technique relies on multirate processing and linear filtering and uses the carrier frequencies to isolate the contribution of linear and nonlinear basis functions to the desired bands. This approach can be used with any MIMO model structure. In particular, models are linear in the parameters of low computational complexity. The technique was evaluated using three concurrent carriers of 50 MHz each fed to a Doherty amplifier. The results show significant reduction in the error vector magnitude and improvements for the transmitter efficiency using the proposed compensation technique.
Autors: Efrain Zenteno;Daniel Rönnow;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Mar 2017, volume: 65, issue:3, pages: 967 - 979
Publisher: IEEE
 
» Minimization of System-Level Losses in VSI-Based Induction Motor Drives: Offline Strategies
Abstract:
Applications of motor drives, ranging from automotive traction to more-electric aircraft, have widely varying speed and torque demands. With extensive use of inverter-fed drives, loss minimization techniques for such applications have evolved over the past few decades. Previous work on loss minimization has mainly focused on specific drive components. Component-level loss minimization, however, will not guarantee minimum total loss in the drive system. In this paper, a system-level loss minimization method is developed using a comprehensive loss model, to achieve true minimum total loss in the system. The total loss obtained is lower for the proposed system-based minimization than the component-based methods such as machine loss minimization, torque maximization per stator ampere, and dc-link loss minimization. Simulation and experimental results for a sample drive cycle are presented to verify the benefits of the proposed scheme for an induction motor drive. Results suggest system loss reduction of about 7%, when compared to machine-based optimization, in high-variability applications.
Autors: Srikanthan Sridharan;Philip T. Krein;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1096 - 1105
Publisher: IEEE
 
» Mining Multitemporal In Situ Heterogeneous Monitoring Information for the Assurance of Recorded Land Cover Changes
Abstract:
We present a data mining methodology to filter and validate land cover change detections obtained from multitemporal in situ surveys. As in situ data we use the measurements from the European land use and coverage area frame survey (LUCAS), which provides images with standardized metadata about land cover and land use within the whole territory of the European Union. Multitemporal LUCAS surveys present an anomaly in the amount of land cover changes that disagree with the estimated by experts. Therefore, our methodology analyses the available data in order to explain the existing irregularities in them. The initial step of our methodology is based on database query refinements. The data mining methodology continues with an image analysis process. This analysis calculates similarity measures of the multitemporal images that are used to identify the potential misclassifications. The final step involves a geographic information system based on web technologies. By defining different color codes assigned by the similarity measures, the system represents the examined points on a digital Earth globe. There, a user can easily discriminate potentially misclassified points for subsequent detailed analysis or corrections. The final output of the methodology shows remarkable results for detecting misclassified land cover changes.
Autors: Kevin Alonso;Daniela Espinoza-Molina;Mihai Datcu;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Mar 2017, volume: 10, issue:3, pages: 877 - 887
Publisher: IEEE
 
» MIP Reformulation for Max-Min Problems in Two-Stage Robust SCUC
Abstract:
With increasing renewable penetration in power systems, considerable research efforts have been focused on how to accommodate the uncertainties from renewables in the Security-Constraint Unit Commitment (SCUC) problem. One of the candidate approaches to handling uncertainties is the two-stage Robust SCUC (RSCUC), which enables system to survive in any scenario. The survivability is guaranteed by the solution optimality of the max-min problem in the second stage. However, as the non-convex max-min problem is NP-hard, it is difficult to get the exact optimal solution in acceptable time. In this paper, we propose a new efficient formulation which recasts the max-min problem to a Mixed Integer Programming (MIP) problem using Binary Expansion (BE). The upper bound of the gap between the new MIP problem and the original max-min problem is derived. The gap, which quantifies the solution optimality of the max-min problem, is controllable. Two effective acceleration techniques are proposed to improve the performance of the MIP problem by eliminating inactive flow constraints and decomposing time-coupled uncertainty budget constraints. Accordingly, the computation burden of solving the max-min problem is reduced tremendously. The simulation results for the IEEE 118-Bus system validate and demonstrate the effectiveness of the new BE-based solution approach to the two-stage RSCUC and the acceleration techniques.
Autors: Hongxing Ye;Jianhui Wang;Zuyi Li;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1237 - 1247
Publisher: IEEE
 
» Mitigation of Intra-coil Eddy Currents in Split Gradient Coils in a Hybrid MRI-LINAC System
Abstract:
Objective: The aim of this study is to mitigate intra-gradient coil eddy currents in a hybrid MRI-LINAC system. Methods: The tracks of the gradient coils are modified by cutting slits along the current flow direction. The electromagnetic model developed was first experimentally validated and then used to study the impacts of the slit conductors on the energized and surrounding coils. In this study, gradient coils were slit with different numbers of sub-tracks and driven by a current with frequencies ranging from 100 Hz to 10 kHz. The proposed configuration was assessed by evaluating a number of system parameters, such as the gradient magnetic field, the power loss generated in the surrounding unenergized coil (hereafter referred to as passive coils), and the performance of the energized coil. Results: It was found that at a typical operating frequency of 1 kHz and compared with a conventional (no cut) split coil structure, the new coil pattern (with four slits) offered improved coil parameters. 1) The average power loss dissipated in the surrounding passive coil was significantly reduced by 85%, 2) the cuts largely reduced the secondary field generated by the eddy currents in the passive coil, which was reduced to about 4% of that produced by the uncut coil and, 3) the performance of the energized coil with slit tracks was significantly improved. Some typical gradient coil parameters, such as the figure of merit, efficiency (η), and (where η is the efficiency and R is the resistance), were improved by 8.0%, 11.9%, and 45.7%, respectively. Conclusion and Significance: The new slit coil structure is effective in mitigating intra-coil eddy current effects, which is an important issue in the MRI-LINAC system.
Autors: Fangfang Tang;Fabio Freschi;Maurizio Repetto;Yu Li;Feng Liu;Stuart Crozier;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Mar 2017, volume: 64, issue:3, pages: 725 - 732
Publisher: IEEE
 
» Mitigation of Ionospheric Scintillation Effects on GNSS Signals Using Variational Mode Decomposition
Abstract:
This letter addresses the problem of ionospheric scintillation effects on the global navigation satellite system (GNSS) signals. Severe scintillations degrade the signal intensity below the fade margin of the GNSS receiver, resulting in failure of the positioning and navigational services. A robust methodology is needed for the estimation and mitigation of such ionospheric scintillation effects. Hence, in this letter, the application of an adaptive signal decomposition technique based on variational mode decomposition (VMD), in combination with the detrended fluctuation analysis (DFA) method, is reported. VMD-DFA effectively decomposes the GNSS signal affected by ionospheric scintillations into a number of intrinsic mode functions and provides a threshold for the detection and mitigation of scintillations noise. Monte Carlo simulation results demonstrate that the proposed algorithm is superior and reliable for eliminating the amplitude scintillation effects compared to the complementary ensemble empirical mode decomposition method. The application of the proposed algorithm on both synthetic (Cornell scintillation model) and real-time measured GNSS data obtained from GNSS software navigation receiver at Rio de Janeiro, Brazil, has shown its potentiality in mitigating the ionospheric amplitude scintillation effects.
Autors: G. Sivavaraprasad;R. Sree Padmaja;D. Venkata Ratnam;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Mar 2017, volume: 14, issue:3, pages: 389 - 393
Publisher: IEEE
 
» Mitigation of Voltage Variation by REMS for Distribution Feeders
Abstract:
This study develops a renewable energy management system (REMS) for the control of photovoltaic (PV) smart inverters to mitigate the voltage violation of distribution systems with high penetration of PV installation. The impact analysis of distribution feeders with the PV system integration for decision making of smart inverter control has been embedded in REMS to solve the voltage violation problem. To verify the effectiveness of the proposed REMS to enhance the system voltage quality, a PV system installed in a distribution feeder of Taiwan Power Company (Taipower) has been selected for field testing. The real power, reactive power, and voltage of the studied PV system have been collected. The impact analysis of PV integration is performed to solve the mitigation of voltage variation by the control of reactive power compensation of smart inverters. It is found that the voltage at the test PV system is very consistent with the field test results. The computer simulation of a distribution feeder with a large PV farm has been executed to illustrate that the control of smart inverters can enhance the utilization of solar energy by reducing the curtailment of renewable power generation dramatically for a distribution system with high penetration of PV systems.
Autors: Chih-Chieh Yeh;Chao-Shun Chen;Te-Tien Ku;Chia-Hung Lin;Cheng-Ting Hsu;Hui-Jen Chuang;Hung-Yi Yu;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 901 - 907
Publisher: IEEE
 
» MMB$^{cloud}$ -Tree: Authenticated Index for Verifiable Cloud Service Selection
Abstract:
Cloud brokers have been recently introduced as an additional computational layer to facilitate cloud selection and service management tasks for cloud consumers. However, existing brokerage schemes on cloud service selection typically assume that brokers are completely trusted, and do not provide any guarantee over the correctness of the service recommendations. It is then possible for a compromised or dishonest broker to easily take advantage of the limited capabilities of the clients and provide incorrect or incomplete responses. To address this problem, we propose an innovative cloud service selection verification (CSSV) scheme and index structures (MMB-tree) to enable cloud clients to detect misbehavior of the cloud brokers during the service selection process. We demonstrate correctness and efficiency of our approaches both theoretically and empirically.
Autors: Jingwei Li;Anna Cinzia Squicciarini;Dan Lin;Smitha Sundareswaran;Chunfu Jia;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Mar 2017, volume: 14, issue:2, pages: 185 - 198
Publisher: IEEE
 
» MMSE State Estimation Approach for Linear Discrete-Time Systems With Time-Delay and Multi-Error Measurements
Abstract:
This technical note focuses on designing a novel optimal estimation approach for linear discrete-time systems with time-delay and multi-error measurements, inspired by the measurement demands of the Five-hundred-meter Aperture Spherical radio Telescope. Measurement errors from different measurement channels, which are considered equal in many previous estimation methods, are usually negatively correlated with time-delays. Measurements with higher time-delays usually have less errors than the ones with lower delays. Our approach improves the estimation accuracy by decreasing the usage rate of measurements with larger errors. To prove the optimality of the approach in the minimum mean square error sense, a derivation procedure is presented. A numerical example and comparison are also given to demonstrate the feasibility and advantage of the proposed approach.
Autors: Yao Sun;Fengshui Jing;Zize Liang;Min Tan;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Mar 2017, volume: 62, issue:3, pages: 1530 - 1536
Publisher: IEEE
 
» Mobile Data Offloading With Almost Blank Subframe in LTE-LAA and Wi-Fi Coexisting Networks Based on Coalition Game
Abstract:
The problem of spectrum scarcity has raised the prospect of coexisting network. For example, long-term evolution-licensed-assisted access (LTE-LAA & Wi-Fi) can operate in the same frequency band. However, interference between the two different radio access technologies can severely reduce the performances of both networks. To mitigate this interference, the concept of an almost blank subframe (ABS) has been proposed. However, because the LTE-LAA macrocell must remain silent, this provides no incentive for its throughput enhancement. In this letter, we propose a transaction between LTE-LAA and Wi-Fi using ABS together with offloading. We model a time-resource utility model by jointly considering the resource consumed for ABS and offloading, and then formulate a coalition game. To achieve the solution of a coalition game, we consider two fairness concepts: min-max and Shapley fairness. We then verify the performance of the proposed game using simulations. It is shown that the proposed game model can improve resource utilization through the joint use of ABS and offloading.
Autors: Byung Chang Chung;Dong-Ho Cho;
Appeared in: IEEE Communications Letters
Publication date: Mar 2017, volume: 21, issue:3, pages: 608 - 611
Publisher: IEEE
 
» Mobile Demand Profiling for Cellular Cognitive Networking
Abstract:
In the next few years, mobile networks will undergo significant evolutions in order to accommodate the ever-growing load generated by increasingly pervasive smartphones and connected objects. Among those evolutions, cognitive networking upholds a more dynamic management of network resources that adapts to the significant spatiotemporal fluctuations of the mobile demand. Cognitive networking techniques root in the capability of mining large amounts of mobile traffic data collected in the network, so as to understand the current resource utilization in an automated manner. In this paper, we take a first step towards cellular cognitive networks by proposing a framework that analyzes mobile operator data, builds profiles of the typical demand, and identifies unusual situations in network-wide usages. We evaluate our framework on two real-world mobile traffic datasets, and show how it extracts from these a limited number of meaningful mobile demand profiles. In addition, the proposed framework singles out a large number of outlying behaviors in both case studies, which are mapped to social events or technical issues in the network.
Autors: Angelo Furno;Diala Naboulsi;Razvan Stanica;Marco Fiore;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Mar 2017, volume: 16, issue:3, pages: 772 - 786
Publisher: IEEE
 

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