Electrical and Electronics Engineering publications abstract of: 07-2017 sorted by title, page: 11

» Normally-Off LPCVD-SiNx/GaN MIS-FET With Crystalline Oxidation Interlayer
Abstract:
Developing effective technique to protect the etched- GaN surface from the degradation in a high-temperature (i.e., at ~ 780°C) process, such as low-pressure chemical vapor deposition (LPCVD), is essential for fabricating normally-off GaN MIS-FETs with high-quality dielectric/GaN interface and highly reliable gate dielectric. In this letter, we developed an approach of obtaining such a protection layer using oxygen-plasma treatment followed by in situ annealing prior to the LPCVD-SiNx deposition. A sharp and stable crystalline oxidation interlayer (COIL) between the LPCVD-SiNx and etched-GaN was successfully formed. The LPCVD-SiNx/GaN MIS-FETs with COIL deliver normally-off operation with a of 1.15 V, small on-resistance, small hysteresis, and thermally stable .
Autors: Mengyuan Hua;Jin Wei;Gaofei Tang;Zhaofu Zhang;Qingkai Qian;Xiangbin Cai;Ning Wang;Kevin J. Chen;
Appeared in: IEEE Electron Device Letters
Publication date: Jul 2017, volume: 38, issue:7, pages: 929 - 932
Publisher: IEEE
 
» Note on Minimax Sliding Mode Control Design for Linear Systems
Abstract:
The technical note studies the problem of sliding mode control design for linear systems with incomplete and noisy measurements of the output and additive/multiplicative exogenous disturbances. First, we construct a linear minimax observer to have an estimate of the system's state with minimal worst-case error. Second, we establish the optimality of the constructed observer in the class of all observers represented by measurable functionals of the output. Finally, we propose an algorithm, generating continuous and discontinuous feedbacks, which steers the observer as close as possible to a given sliding hyperplane in finite time. The optimality (sub-optimality) of the designed feedbacks is proven for the case of bounded noises and additive (multiplicative) disturbances of -class. The efficacy of the proposed algorithm is illustrated by a numerical example.
Autors: Sergiy Zhuk;Andrey Polyakov;Olexander Nakonechnyi;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3395 - 3400
Publisher: IEEE
 
» Novel Approach for Analysis and Design of High-Speed Electrical Impedance Tomographic System for Void Fraction Measurements in Fast Two-Phase Flows
Abstract:
Electrical impedance tomography is a non-invasive imaging technique capable of void fraction measurements of two-phase flows at high-acquisition rates. This paper presents the design features of an in-house developed prototype fast EIT system and a 16 electrodes sensor. With simplified system architecture, the voltage of the excitation signal is controlled and the current is measured. The proposed full scan data collection strategy opens up new prospects for novel flow regime identification and image reconstruction techniques currently under development. A new calibration procedure that is based on the data from full scan strategy provides reliable absolute measurements in applications, where reference measurements are not available or reliable (e.g., gas-liquid flows with drifts of liquid phase temperature). Experimental results are compared with the analytical and numerical solutions. Fundamental studies for understanding the contact impedance give insight on the influence of important parameters: excitation frequency and liquid conductivity. The quality of the measurements at different frame rates is analyzed. The repeatability at 80 kHz of the prototype highlights similar figure of merit than reported fast EIT systems. The increase in frame acquisition rate allows up to 6250 frames per second for adjacent strategy and up to 833 frames per seconds for full scan strategy.
Autors: Antoine Dupré;Guillaume Ricciardi;Salah Bourennane;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4472 - 4482
Publisher: IEEE
 
» Novel Extension of SBR–PO Method for Solving Electrically Large and Complex Electromagnetic Scattering Problem in Half-Space
Abstract:
To extend hybrid high-frequency shooting and bouncing rays–physical optics (SBR–PO) method to the modeling of electromagnetic (EM) scattering from an object in half-space, this paper focuses on addressing two key issues: 1) how to accurately obtain the induced electric currents on the object surface by taking into account the EM interactions between the object and half-space and 2) how to accurately calculate far-fields in half-space configuration. First, by introducing virtual interface of half-space, the proposed method avoids physically modeling the underlying ground, and only induced electric currents on the object are effectively taken into account in the SBR process. Second, the closed-form half-space Green’s function is used to calculate scattered far-fields to avoid the time-consuming evaluation of the Sommerfeld integrals. The computational errors are only from the approximation of induced electric currents with the same level of the SBR–PO method for the solution of the free-space problem, so the proposed method is more accurate than the conventional SBR–PO technique. Besides, performing the proposed method on the graphics processing unit platform to further accelerate the ray-tracing process makes the method even more powerful to solve the extra-large-scale scattering problems in the half-space.
Autors: Wei Yang;Chun Yun Kee;Chao-Fu Wang;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jul 2017, volume: 55, issue:7, pages: 3931 - 3940
Publisher: IEEE
 
» Novel FPGA-based Methodology for Early Broken Rotor Bar Detection and Classification Through Homogeneity Estimation
Abstract:
Early detection of induction-motor faults has been an increasing matter of research in the last few years. The reliable identification of broken rotor bars (BRB) is still under investigation as it is one of the most common and difficult-to-detect faults in induction motors. Many methods have been proposed to deal with this issue. Recent approaches combine techniques looking for improving the performance of the diagnosis. Their major disadvantage is the high computational requirements, which restrains them from being used in online detection. The contribution in this paper is twofold. The first one is a novel methodology for induction motor BRB detection and the fault severity classification using homogeneity as index, which, to the best of our knowledge, has never been used as an indicator for fault diagnosis, analyzing one phase of the induction motor startup-transient current. Because of the low computational complexity in homogeneity calculation, the second contribution of this paper is a hardware-processing unit based on a field programmable gate array device for online detection and classification of BRB. Obtained results demonstrate the high efficiency of the proposed methodology as a deterministic technique for incipient BRB diagnosis in induction motors, which can detect and differentiate among half, one, or two BRBs with a certainty greater than 99.7%.
Autors: Rocio A. Lizarraga-Morales;Carlos Rodriguez-Donate;Eduardo Cabal-Yepez;Misael Lopez-Ramirez;Luis M. Ledesma-Carrillo;Edna R. Ferrucho-Alvarez;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jul 2017, volume: 66, issue:7, pages: 1760 - 1769
Publisher: IEEE
 
» Novel High-Power Nonresonant Multichannel LED Driver
Abstract:
This paper reports a multichannel high-power light-emitting diode (LED) driver employing a single-stage dc–dc power conversion and control technique with dimming capability. A half-bridge nonresonant converter with symmetrical quadrupler rectifier output is implemented to convert available dc power to multiple current regulated dc outputs for driving LED loads. The dc–dc power conversion efficiency of about 98% is obtained from advantageous operation of the converter with complete soft switching of all semiconductor devices and reduction in power conversion stages. The driver possesses inherent protection against LED failures due to its topology for both electrically open and short-circuit conditions of the LEDs. This patented converter is applicable for high-power LED lighting.
Autors: Ramprakash Kathiresan;Pritam Das;Thomas Reindl;Sanjib Kumar Panda;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5851 - 5864
Publisher: IEEE
 
» Novel Isolated Power Conditioning Unit for Micro Wind Turbine Applications
Abstract:
This paper presents a novel power conditioning unit (PCU) for variable-speed micro wind turbine applications. It contains a simple generator-side rectifier, galvanic isolation with a simple dc–dc converter, and a single-phase full-bridge inverter at the grid side. Variable-speed micro wind turbines based on a permanent magnet synchronous generator (PMSG) are increasingly used in residential and small commercial buildings, despite their relatively low output voltage. Therefore, they can be used easily for battery charging, while their grid integration requires a PCU with galvanic isolation. Most of available PCUs provide no galvanic isolation, or use relatively complicated topologies or four stage energy conversion for that purpose. The dc–dc converter proposed allows reducing the complexity of the PCU. Steady-state analysis shows that the converter is capable of regulating voltage in a wide range suitable for micro wind turbines, which is supported by experimental results within the input voltage range of 40–400 V. The prototype built for integration of a 1.3-kW PMSG-based micro wind turbine shows good performance over the entire 1:5 range of the given wind turbine output voltage. A study of efficiency and power losses was conducted according to the wind turbine power profile.
Autors: Andrii Chub;Oleksandr Husev;Andrei Blinov;Dmitri Vinnikov;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5984 - 5993
Publisher: IEEE
 
» Novel Online Optimal Bandwidth Search and Autotuning Techniques for Servo Motor Drives
Abstract:
The main theme of this paper is to propose fast online optimal bandwidth search and controller tuning techniques for servo motor drives. The proposed controller tuning method derives the controller gains by searching the optimal bandwidth and identifying the inertia. The optimal bandwidth search can be achieved before oscillation occurs. It will be shown that the gains of speed controller of servo drives are tuned automatically to reflect the load variation. Experimental results derived from digital signal processor-controlled permanent magnet synchronous motor servo drives will be shown. The results demonstrate online optimal bandwidth search and autogain tuning can be achieved without motor and load information in prior. These results fully support the developed techniques and claims.
Autors: Chih-Jung Hsu;Yen-Shin Lai;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3635 - 3642
Publisher: IEEE
 
» Novel Variable-Field Machine With a Three-Dimensional Magnetic Circuit
Abstract:
We propose a novel variable-field machine with toroidal windings to achieve both miniaturization and high efficiency. The proposed machine is characterized by a structure that uses three-dimensional (3-D) magnetic flux to increase the number of torque-generation faces. The 3-D structure prevents an increase in the machine volume due to the addition of variable-field coils. We investigated the principle of variable-field function using finite-element analysis and experimentation. We verified that the induced voltage and torque can be changed by regulating the direct current in the variable-field coil. Moreover, the field current revealed the effect of the no-load loss.
Autors: Masafumi Namba;Kenji Hiramoto;Hideo Nakai;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3404 - 3410
Publisher: IEEE
 
» Numerical Simulation and Experimental Validation of the Critical Pressure Value in Ferromagnetic Fluid Seals
Abstract:
Ferrofluids have various engineering applications, and one of them is magnetic fluid seals. Development for this design is a complex process, which requires knowledge about ferrofluid physical properties and magnetic field distribution inside the sealing gap. One of the most important parameters of ferromagnetic fluid seals is a critical pressure value. It is a pressure at which rapid leakage will occur. This publication presents the results of critical pressure value obtained from experimental studies and calculations based on numerical simulations. Shape of sealing stage, volume of ferrofluid, and volume of permanent magnet used in seal construction were taken into account. Experiments and calculations were performed for four ferrofluids differ in saturation magnetization, density, and zero magnetic field viscosity.
Autors: Marcin Szczęch;Wojciech Horak;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jul 2017, volume: 53, issue:7, pages: 1 - 5
Publisher: IEEE
 
» Numerical Study of Convective Heat Transfer in the End Regions of a Totally Enclosed Permanent Magnet Synchronous Machine
Abstract:
This paper proposes a numerical approach for the accurate estimation of convective heat transfer coefficients in the end region of an integrated starter generator (ISG) used in a mild-hybrid vehicle. A simplified numerical model based on CFD methods is developed to provide a qualitative understanding of the mechanism of convective heat transfer over a large operation range. The effect of the rotation speed on the variation of the convective heat transfer coefficients inside the end region is thoroughly investigated. Heat flux paths are also identified for the entire operation range. CFD calculation results are used to provide an enhancement to Schubert's correlation for the different surfaces delimiting the end region of the ISG. Subsequently, general correlations are defined using averaged Nusselt numbers as a function of Reynolds numbers. Then, a detailed lumped thermal network is developed which estimates correctly the temperature distribution in different areas of the electrical machine. The obtained numerical data are validated using local temperature measurements.
Autors: Ayoub Ben Nachouane;Abdenour Abdelli;Guy Friedrich;Stéphane Vivier;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3538 - 3547
Publisher: IEEE
 
» Numerical Vector Green’s Function for S-Parameter Measurement With Waveport Excitation
Abstract:
We present a numerical vector Green’s function that directly links the object material property within the electric field volume integral equation (VIE) to the scattered S-parameters. This Green’s function is particularly useful for microwave inverse scattering applications in which S-parameter measurements are used to reconstruct the dielectric properties of unknown objects in an inhomogeneous background where the Green’s function does not have an analytic form. Unlike the dyadic Green’s function in a standard VIE, which relates the fields in the object domain (vector) to the scattered fields (vector), this vector Green’s function kernel relates the object domain fields (vector) to the measured S-parameters (scalar). Also this new vector Green’s function uses a waveport source method, which accurately accounts for the measured scattered S-parameters between antenna feeds of arbitrary impedance and modes. A detailed derivation is presented, and simulated and experimental examples are provided to validate this vector Green’s function for the prediction of scattered S-parameters.
Autors: Guanbo Chen;John Stang;Mahta Moghaddam;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3645 - 3653
Publisher: IEEE
 
» Nutrient Sensing Using Chip Scale Electrophoresis and In Situ Soil Solution Extraction
Abstract:
This paper reports an electrophoresis-based microfluidic ion nutrient sensor for the detection of anions in soil solution samples. The sensor is able to analyze the concentration of various anions in extracted soil solutions with high sensitivity as well as high specificity, while it is an approach requiring no labels. The electrophoretic microchip integrates a pair of in-plane conductivity detection microelectrodes. A programmable high voltage power supply unit was designed to achieve precise control over voltage potentials needed for sample and buffer injection and ion separation. An electrical conductivity detector was designed to extract and process the changes in conductivity due to the arrivals of separated anions at the electrodes at various times. An arrival time serves to identify an anionic species, while the peak height indicates the concentration. A soil water extraction device was also designed to extract the soil solution analyte from the bulk soil, by applying vacuum suction. Only a minute amount of solution (on the order of L) is needed for the electrophoretic measurement. Extracted soil solutions were analyzed for ionic concentrations to demonstrate the feasibility of using this microfluidic sensor, showing a limit of detection of about M.
Autors: Zhen Xu;Xinran Wang;Robert J. Weber;Ratnesh Kumar;Liang Dong;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4330 - 4339
Publisher: IEEE
 
» Oasis: Scaling Out Datacenter Sustainably and Economically
Abstract:
As big data applications proliferate, datacenters today are increasingly looking to adopt a scale-out model. Nevertheless, power capacity has become an important bottleneck that restricts horizontal scaling of servers, especially in datacenters that oversubscribe power infrastructure. When a datacenter hits its ceiling for power provisioning, conventionally the owner has to either build another facility or upgrade existing infrastructure—both approaches add huge cost, require significant time, and can further increase carbon footprint. This paper proposes Oasis, a novel datacenter expansion strategy that enables power-/carbon- constrained servers to scale out economically and sustainably. The basic structure of Oasis, called Oasis Node, naturally supports incremental capacity expansion with near-zero environmental impact since it leverages modular solar panels and distributed battery systems to power newly added servers. To optimize the operation of newly added nodes, we further propose a management framework called Ozone. It allows Oasis to jointly perform power supply switching and server speed scaling to improve efficiency locally and globally. We implement a prototype of Oasis and use it as a research platform for evaluating the design tradeoffs of green scale-out datacenters. With Oasis, a green datacenter could gradually double its capacity with near-oracle performance, extended battery lifetime, and 26 percent cost savings.
Autors: Chao Li;Yang Hu;Juncheng Gu;Jingling Yuan;Tao Li;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jul 2017, volume: 28, issue:7, pages: 1960 - 1973
Publisher: IEEE
 
» Object Detection Networks on Convolutional Feature Maps
Abstract:
Most object detectors contain two important components: a feature extractor and an object classifier. The feature extractor has rapidly evolved with significant research efforts leading to better deep convolutional architectures. The object classifier, however, has not received much attention and many recent systems (like SPPnet and Fast/Faster R-CNN) use simple multi-layer perceptrons. This paper demonstrates that carefully designing deep networks for object classification is just as important. We experiment with region-wise classifier networks that use shared, region-independent convolutional features. We call them “Networks on Convolutional feature maps” (NoCs). We discover that aside from deep feature maps, a deep and convolutional per-region classifier is of particular importance for object detection, whereas latest superior image classification models (such as ResNets and GoogLeNets) do not directly lead to good detection accuracy without using such a per-region classifier. We show by experiments that despite the effective ResNets and Faster R-CNN systems, the design of NoCs is an essential element for the 1st-place winning entries in ImageNet and MS COCO challenges 2015.
Autors: Shaoqing Ren;Kaiming He;Ross Girshick;Xiangyu Zhang;Jian Sun;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jul 2017, volume: 39, issue:7, pages: 1476 - 1481
Publisher: IEEE
 
» Observability Analysis for Dynamic State Estimation of Synchronous Machines
Abstract:
This paper is concerned about the observability analysis of time-varying nonlinear dynamic model of a synchronous generator with its associated control systems. A byproduct of observability study is a set of guidelines to choose the appropriate set of measurements or sensors to be used to ensure strong observability for the dynamic states. The proposed analysis is developed using a Lie derivative based observability matrix and its singular values. A two-axis synchronous generator model and an associated IEEE-Type1 exciter are used to validate the results of observability analysis with dynamic simulations of disturbance scenarios using different types of measurements. It is shown that the dynamic state estimates will converge to the true trajectory faster and smoother if appropriate measurements that provide higher level of observability based on the proposed analysis are chosen. Results can be extended to other dynamic elements such as loads or time-varying parameters of machines.
Autors: Alireza Rouhani;Ali Abur;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 3168 - 3175
Publisher: IEEE
 
» Octahedron-Shaped Linearly Polarized Antenna for Multistandard Services Including RFID and IoT
Abstract:
In this paper, a novel topology of the coplanar waveguide fed truncated octahedron-shaped antenna is proposed. The linearly polarized antenna operates over the triple radio frequency identification technique (RFID) bands of 858–930MHz, 2.4–2.454 GHz, and 5.725–5.875 GHz at ultrahigh frequency (UHF), microwave-, and super high-frequency bands, respectively. In addition, it also supports long-term evolution 4G, TV broadcasting, and 5G bands of the electromagnetic spectrum. The dB impedance bandwidth is 294 MHz (697–991 MHz), 120 MHz (2.38–2.5 GHz), 310 MHz (3.07–3.35 GHz), and 310 MHz (5.61–5.92 GHz) in the various bands. The antenna is fabricated on a polyguide substrate of dimension, where is the free-space wavelength at the lowest operating frequency. The antenna’s and the radiation patterns have been measured, and a good agreement between simulated and the measured results has been found. In addition, the proposed antenna is also experimentally verified for the UHF band RFID detection and the global standard for mobile communications 900 band cellular applications. We also propose a system-level schematic to integrate this antenna to other communication standards for the automated RFID applications needed for the Internet of Things.
Autors: Ubaid Bashir;Kumud Ranjan Jha;Ghanshyam Mishra;Ghanshyam Singh;Satish Kumar Sharma;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3364 - 3373
Publisher: IEEE
 
» Odor Recognition in Multiple E-Nose Systems With Cross-Domain Discriminative Subspace Learning
Abstract:
In this paper, we propose an odor recognition framework for multiple electronic noses (E-noses), machine olfaction odor perception systems. Straight to the point, the proposed transferring odor recognition model is called cross-domain discriminative subspace learning (CDSL). General odor recognition problems with E-nose are single domain oriented, that is, recognition algorithms are often modeled and tested on the same one domain data set (i.e., from only one E-nose system). Different from that, we focus on a more realistic scenario: the recognition model is trained on a prepared source domain data set from a master E-nose system A, but tested on another target domain data set from a slave system B or C with the same type of the master system A. The internal device parameter variance between master and slave systems often results in data distribution discrepancy between source domain and target domain, such that single-domain-based odor recognition model may not be adapted to another domain. Therefore, we propose domain-adaptation-based odor recognition for addressing the realistic recognition scenario across systems. Specifically, the proposed CDSL method consists of three merits: 1) an intraclass scatter minimizationand an interclass scatter maximization-based discriminative subspace learning is solved on source domain; 2) a data fidelity and preservation constraint of the subspace is imposed on target domain without distortion; and 3) a minipatch feature weighted domain distance is minimized for closely connecting the source and target domains. Experiments and comparisons on odor recognition tasks in multiple E-noses demonstrate the efficiency of the proposed method.
Autors: Lei Zhang;Yan Liu;Pingling Deng;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jul 2017, volume: 66, issue:7, pages: 1679 - 1692
Publisher: IEEE
 
» OFDM Chirp Waveform Diversity Design With Correlation Interference Suppression for MIMO Radar
Abstract:
The orthogonal frequency-division multiplexing (OFDM) chirp waveform has attracted much attention due to its high range resolution, low peak-to-average ratio, and large time-bandwidth product. In its application to multiple-input multiple-output radar, the correlation property of multiple OFDM chirp waveforms should be considered primarily for good detection performance. The simulation results show that high sidelobes exist in correlation functions of the conventional waveforms. In this letter, the reason for high correlation sidelobes is explored first, which is the equal subchirp durations and the same subcarrier bandwidth. Second, two new OFDM chirp waveform diversity design schemes are proposed to suppress the correlation interference. Via designing the various subchirp durations or subcarrier bandwidths specially, the high sidelobes are depressed and the correlation property is improved. Both simulation results and comparisons verify the effectiveness of the proposed methods.
Autors: Hui Li;Yongbo Zhao;Zengfei Cheng;Dazheng Feng;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jul 2017, volume: 14, issue:7, pages: 1032 - 1036
Publisher: IEEE
 
» On Applicability of Auxiliary System Approach to Detect Generalized Synchronization in Complex Network
Abstract:
Generalized synchronization is ubiquitous in nature. It is well known that the auxiliary system approach has been widely used to verify the presence of generalized synchronization. This approach was firstly proposed in a drive-response system, then extended to the bidirectionally coupled systems and complex networks. However, the well-known generalized auxiliary system method lacks a rigorous theoretical basis for its various applications. Two recent counterexamples indicate us the inapplicability of this method. Inspired by the counterexamples, we find that it is interesting to ask the following two fundamental questions: i) Why is the generalized auxiliary system approach unworkable in the networks with bidirectional couplings? ii) Are there any essential conditions for the applications of this approach? This technical note aims at establishing a rigorous theoretical basis for the applicability of auxiliary system approach. That is, the generalized auxiliary system approach is effective only if there does not exist any path from nodes to their driving neighbors (who drive these nodes) in a network. Several representative examples are also given to validate our theoretical results.
Autors: Jin Zhou;Juan Chen;Junan Lu;Jinhu Lü;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3468 - 3473
Publisher: IEEE
 
» On Detecting Road Regions in a Single UAV Image
Abstract:
Automatic detection of road regions in aerial images remains a challenging research topic. Most existing approaches work well on the requirement of users to provide some seedlike points/strokes in the road area as the initial location of road regions, or detecting particular roads such as well-paved roads or straight roads. This paper presents a fully automatic approach that can detect generic roads from a single unmanned aerial vehicles (UAV) image. The proposed method consists of two major components: automatic generation of road/nonroad seeds and seeded segmentation of road areas. To know where roads probably are (i.e., road seeds), a distinct road feature is proposed based on the stroke width transformation (SWT) of road image. To the best of our knowledge, it is the first time to introduce SWT as road features, which show the effectiveness on capturing road areas in images in our experiments. Different road features, including the SWT-based geometry information, colors, and width, are then combined to classify road candidates. Based on the candidates, a Gaussian mixture model is built to produce road seeds and background seeds. Finally, starting from these road and background seeds, a convex active contour model segmentation is proposed to extract whole road regions. Experimental results on varieties of UAV images demonstrate the effectiveness of the proposed method. Comparison with existing techniques shows the robustness and accuracy of our method to different roads.
Autors: Hailing Zhou;Hui Kong;Lei Wei;Douglas Creighton;Saeid Nahavandi;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Jul 2017, volume: 18, issue:7, pages: 1713 - 1722
Publisher: IEEE
 
» On Diagnosing the Aging Level of Automotive Semiconductor Devices
Abstract:
Semiconductor aging is a serious threat to the reliability of a system. We address the aging level of semiconductor components by describing the degree of semiconductor aging under certain operating conditions, including voltage, frequency, temperature, and usage rate. Aging level information can be used to follow the real aging rate of a device, predict the remaining life, and control the device performance under certain degradation conditions by balancing the operation of various device components. Such applications can improve the reliability of automotive semiconductor systems, which should have longer lives than mobile systems. In this brief, we present an aging level estimating flip-flop (FF) that can be used for these and other applications as well. Moreover, we can control the operation of the proposed FF by controlling its clock and control signals. We demonstrate an application of the proposed FF for aging-monitoring, showing that, by halting the operation of the proposed FF, the power consumption is significantly reduced compared with other approaches.
Autors: Jihun Jung;Muhammad Adil Ansari;Dooyoung Kim;Hyunbean Yi;Sungju Park;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2017, volume: 64, issue:7, pages: 822 - 826
Publisher: IEEE
 
» On Die Bit Error Rate Estimator for NAND Flash Memory
Abstract:
In this brief, we propose a simple bit error rate (BER) estimator utilizing the parity check constraints of a low-density parity-check code-based error correction coding (ECC) scheme. The proposed estimator can be efficiently implemented on flash memory die with a very small area cost. We articulate applications in which flash memory controllers can take advantage of having the BER estimate before the ECC decoding scheme to significantly reduce programming errors and improve system performance in terms of latency and throughput.
Autors: Mustafa N. Kaynak;Patrick R. Khayat;Sivagnanam Parthasarathy;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2017, volume: 64, issue:7, pages: 772 - 776
Publisher: IEEE
 
» On Efficient Packet-Switched Wireless Networking: A Markovian Approach to Trans-Layer Design and Optimization of ROHC
Abstract:
In packet-switched radio links, the little known Robust Header Compression (ROHC) has become an integral part of many wireless and particularly cellular communication networks. To strengthen existing schemes, this paper aims to improve ROHC performance in terms of payload efficiency for U-mode compression under poor wireless channel conditions. We first consider the parameter optimization of current ROHC systems, for which we propose a Markov compressor model suitable for realistic unidirectional (U-mode) ROHC. We present both the steady-state analysis and the transient behavior analysis of the ROHC. More generally, we propose a novel trans-layer ROHC design concept by exploiting lower cellular network layer status information to adaptively control header compression without dedicated feedbacks. Considering practical delay and inaccuracy when acquiring lower layer information, we develop a ROHC control framework in terms of a partially observable Markov decision process. Our results demonstrate the strength of our Markov ROHC compressor model in characterizing both stationary and transient behaviors, and the significant advantage of the proposed trans-layer ROHC design approach.
Autors: Wenhao Wu;Zhi Ding;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4232 - 4245
Publisher: IEEE
 
» On Estimation and Sensitivity Analysis of Distribution Circuit's Photovoltaic Hosting Capacity
Abstract:
A high penetration of residential photovoltaic (PV) panels can potentially cause a number of operational issues in the distribution circuit, necessitating the requirement to determine the largest PV generation, a distribution circuit can accommodate. This paper presents a Monte Carlo-based hourly stochastic analysis framework to determine a circuit's PV accommodation limit or PV hosting capacity. First, a mathematical formulation of the hosting capacity problem for bus overvoltage concerns is presented, followed by the proposed analysis approach. In the proposed approach, the Monte Carlo method is used to simulate the scenarios of probable PV locations and sizes while the hourly analysis framework is used to include the daily variations in load and PV generation. Next, a method to evaluate the percentage accuracy of the hosting capacity results is presented. The sensitivity of PV hosting results to multiple parameters related to both feeder characteristics and simulation method are evaluated as well. The utility of the proposed framework is presented using an actual 12.47-kV distribution circuit. In sum, by presenting a PV hosting analysis method, accuracy assessment framework, and sensitivity analysis approach, this paper provides a thorough understanding of the PV hosting capacity problem.
Autors: Anamika Dubey;Surya Santoso;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 2779 - 2789
Publisher: IEEE
 
» On Frequency Detection Capability of Full-Rate Linear and Binary Phase Detectors
Abstract:
Until now, it has been known that the full-rate linear and binary phase detectors (PDs) cannot detect the frequency difference between the received data and the recovered clock in clock and data recovery (CDR) loops. In this brief, we study the frequency characteristics of the full-rate linear and binary PDs and show that, unlike the binary PD, the linear PD has not only phase detection capability but also frequency detection capability intrinsically. According to our frequency-locked loop analysis, the locking trajectory of a referenceless CDR with only the full-rate linear PD in the single-loop architecture can be represented by using an exponential decay function with a single time constant. MATLAB Simulink simulations agree well with the predicted locking trajectory, which verifies that the full-rate linear PD has frequency detection capability.
Autors: Chung Hwan Son;Sangjin Byun;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2017, volume: 64, issue:7, pages: 757 - 761
Publisher: IEEE
 
» On Indoor Millimeter Wave Massive MIMO Channels: Measurement and Simulation
Abstract:
The millimeter wave (mmWave) communications and massive multiple-input multiple-output (MIMO) are both widely considered to be the candidate technologies for the fifth generation mobile communication system. It is thus a good idea to combine these two technologies to achieve a better performance for large capacity and high data-rate transmission. However, one of the fundamental challenges is the characterization of mmWave massive MIMO channel. Most of the previous investigations in mmWave channel only focus on single-input single-output links or MIMO links, whereas the research of massive MIMO channels mainly focus on a frequency band below 6 GHz. This paper investigates the channel behaviors of massive MIMO at a mmWave frequency band around 26 GHz. An indoor mmWave massive MIMO channel measurement campaign with 64 and 128 array elements is conducted, based on which, path loss, shadow fading, root-mean-square (RMS) delay spread, and coherence bandwidth are extracted. Then, by using our developed ray-tracing simulator calibrated by the measurement data, we make the extensive ray-tracing simulations with 1024 antenna elements in the same indoor scenario, and get insights into the variation tendency of mean delay and the RMS delay with different array elements. It is observed that the measurement and the ray-tracing-based simulation results have reached a good agreement.
Autors: Bo Ai;Ke Guan;Ruisi He;Jianzhi Li;Guangkai Li;Danping He;Zhangdui Zhong;Kazi Mohammed Saidul Huq;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: Jul 2017, volume: 35, issue:7, pages: 1678 - 1690
Publisher: IEEE
 
» On Integer-Forcing Precoding for the Gaussian MIMO Broadcast Channel
Abstract:
Integer-forcing (IF) precoding, also known as downlink IF, is a promising new approach to communication over multiple-input multiple-output (MIMO) broadcast channels. Inspired by the integer-forcing linear receiver for multiple-access channels, it generalizes linear precoding by inducing an effective channel matrix that is approximately integer, rather than approximately identity. Combined with lattice encoding and a pre-inversion of the channel matrix at the transmitter, the scheme has the potential to outperform any linear precoding scheme, despite enjoying similar low complexity. In this paper, a specific IF precoding scheme, called diagonally scaled exact IF (DIF), is proposed and shown to achieve maximum spatial multiplexing gain. For the special case of two receivers, in the high SNR regime, an optimal choice of parameters is derived analytically, leading to an almost closed-form expression for the achievable sum rate. In particular, it is shown that the gap to the sum capacity is upper bounded by 0.27 bits for any channel realization. For general SNR, a regularized version of DIF (RDIF) is proposed. Numerical results for two receivers under Rayleigh fading show that RDIF can achieve performance superior to optimal linear precoding and very close to the sum capacity.
Autors: Danilo Silva;Gabriel Pivaro;Gustavo Fraidenraich;Behnaam Aazhang;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4476 - 4488
Publisher: IEEE
 
» On Millimeter Wave and THz Mobile Radio Channel for Smart Rail Mobility
Abstract:
As a widely acknowledged efficient and green transportation model, rail traffic is expected to evolve into a new era of “smart rail mobility” whereby infrastructure, trains, and travelers will be interconnected to achieve optimized mobility, higher safety, and lower costs. Thus, a seamless high-data rate wireless connectivity with up to dozens of gigahertz bandwidth is required. Such a huge bandwidth requirement motivates the exploration of the underutilized millimeter (mm) wave and terahertz (THz) bands. In this paper, the motivations for developing millimeter wave and THz communications for railway are clarified by first defining the applications and scenarios required for smart rail mobility. Ray-tracing simulations at 100 GHz imply that to form high-gain directional antenna beams, dynamic beamforming strategies and advanced handover design are critical for the feasibility of THz communications to enable smart rail mobility.
Autors: Ke Guan;Guangkai Li;Thomas Kürner;Andreas F. Molisch;Bile Peng;Ruisi He;Bing Hui;Junhyeong Kim;Zhangdui Zhong;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 5658 - 5674
Publisher: IEEE
 
» On Parametrization of All the Exact Pole-Assignment State-Feedbacks for LTI Systems
Abstract:
In this technical note, we provide a parametrization of all the exact pole-assignment state-feedbacks for LTI systems, when the set of poles to be assigned contains sufficient number of real eigenvalues. We also refute a recent conjecture concerning the explicit form of all the state-feedbacks assigning a given set of poles to the closed-loop.
Autors: Y. Peretz;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3436 - 3441
Publisher: IEEE
 
» On Spectral Analysis of Signed and Dispute Graphs: Application to Community Structure
Abstract:
This paper presents a spectral analysis of signed networks from both theoretical and practical aspects. On the theoretical aspect, we conduct theoretical studies based on results from matrix perturbation for analyzing community structures of complex signed networks and show how the negative edges affect distributions and patterns of node spectral coordinates in the spectral space. We prove and demonstrate that node spectral coordinates form orthogonal clusters for two types of signed networks: graphs with dense inter-community mixed sign edges and -dispute graphs where inner-community connections are absent or very sparse but inter-community connections are dense with negative edges. The cluster orthogonality pattern is different from the line orthogonality pattern (i.e., node spectral coordinates form orthogonal lines) observed in the networks with -block structure. We show why the line orthogonality pattern does not hold in the spectral space for these two types of networks. On the practical aspect, we have developed a clustering method to study signed networks and -dispute networks. Empirical evaluations on both synthetic networks (with up to one million nodes) and real networks show our algorithm outperforms existing clustering methods on signed networks in terms of accuracy and efficiency.
Autors: Leting Wu;Xintao Wu;Aidong Lu;Yuemeng Li;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jul 2017, volume: 29, issue:7, pages: 1480 - 1493
Publisher: IEEE
 
» On the Auction-Based Resource Trading for a Small-Cell Caching System
Abstract:
In this letter, we propose an auction-based resource trading scheme between a network service provider (NSP) and multiple content providers (CPs). The NSP is in charge of a number of small-cell base stations (SBSs), while each CP provides content downloading services to its affiliated mobile users (MUs). By treating the SBSs as a kind of resources, the NSP leases SBSs to the CPs for caching their popular contents, thereby reducing the downloading latency of the MUs. We first establish the utility functions of the NSP and CPs. Then, we maximize the utilities of both sides by formulating an iterative auction problem, in which the NSP (auctioneer) communicates with the CPs (bidders) in an iterative manner for achieving optimal price and resource allocations. Furthermore, to avoid being cheated from the CPs, we adopt an ascending-bid auction mechanism such that the CPs do not have motivations to cheat the NSP for a lower price. Numerical results show that our proposed scheme can effectively allocate SBSs to the CPs and prevent each CP from cheating the NSP for gaining a higher profit.
Autors: Feiran You;Jun Li;Jinhui Lu;Feng Shu;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1473 - 1476
Publisher: IEEE
 
» On the Competition Among Small Cell Wireless Operators with Large Scale Deployments
Abstract:
Recent trends in wireless networking such as small cells and network function virtualization, strongly suggest that the future cellular network will consist of many sub-networks controlled by self-interest operators competing for a share of the revenues associated with the high demand for service. This paper attempts to analyze the future network performance under these new market conditions, taking into account not only engineering properties of the sub-networks, e.g., spectral efficiency, but economic properties as well, i.e., service pricing. Going beyond previous related works, large scale infrastructure deployments over wide geographical areas, targeting a large number of users, are explicitly considered. The focus of the analysis is on the effects of different deployment densities (in units of average number of small cells per unit area) among competing operators as well as random placement of small cells. A game-theoretic system analysis is employed with market equilibrium characterization obtained analytically for the practical cases of two competing operators with arbitrary network characteristics and multiple competing operators with similar network characteristics. Closed form expressions for user and operator utilities at equilibrium are provided, revealing, among others, that extreme infrastructure densification, even though desirable from a purely engineering perspective, may not lead to stable market conditions under the considered competition model.
Autors: Stelios Stefanatos;Angeliki Alexiou;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jul 2017, volume: 16, issue:7, pages: 1981 - 1993
Publisher: IEEE
 
» On the Decay Rate of Discrete-Time Linear Delay Systems With Cone Invariance
Abstract:
This technical note is concerned with the decay rate constrained stability analysis for linear delay systems that possess cone-invariant property. In order to capture the decay rate of such systems, we introduce a nondecreasing positive function whose reciprocal represents the decay rate. Under mild assumptions on the growth rate of this function, an explicit condition is given to ensure that a cone-preserving linear system with unbounded time-varying delays is asymptotically stable with a given decay rate. As typical cases, necessary and sufficient conditions are given to characterize the decay rate when the delay is restricted by a linear, sublinear or logarithmic growth rate. Finally, some numerical examples are given to illustrate the effectiveness of the theoretical results.
Autors: Jun Shen;James Lam;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3442 - 3447
Publisher: IEEE
 
» On the Design of Miniature MedRadio Implantable Antennas
Abstract:
A design frame for developing miniature implant- able antennas at medical device radiocommunications band (401–406 MHz) is being sketched by addressing issues of resonance, efficiency, bandwidth (BW), and robustness. To that end, we visit fundamental design concepts of geometry, impedance matching, and quality factor Q and we show that a very small antenna insensitive to environmental variations and of optimum efficiency can be obtained. It is the first time, to our knowledge, that a Q calculation for miniature implanted antennas is conducted. In this paper, we consider a skin-tissue implantation scenario and planar dipoles with extremely thin profile and small aperture size. Notably, antennas’ physical volume does not exceed 25 mm3. Results indicate a strong dependence of resonance frequency on the antenna geometry for fixed physical size. In addition, external impedance matching proves to be inferior to integral matching via metallization in relation with antenna radiation performance (gain, efficiency, and quality of communication link). Finally, the quality factor Q of small fixed-size antennas highlights the influence of the design on the exhibited resonance and sensitivity response (impedance BW, tolerance to detuning, and gain stability). Simulations are accompanied by measurements with very good agreement underlying the importance of our approach.
Autors: Sofia Bakogianni;Stavros Koulouridis;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3447 - 3455
Publisher: IEEE
 
» On the Discretization Schemes in Map-Aided Indoor Localization
Abstract:
Pedestrian dead reckoning (PDR) implemented on the discretized map is considered as an efficient solution for indoor localization. Finer map discretization can provide better localization accuracy at the cost of higher computation complexity. In this letter, we characterize the effect of map discretization in PDR-based indoor localization. In particular, the closed-form expressions for the localization errors are derived for two typical discretization schemes. We then optimize the quantization intervals by a minimax formulation, which can guarantee the localization accuracy for users with different step sizes. We show that the low-complexity scheme only allowing transitions between adjacent discretization points on the map can achieve a robust and accurate performance when the quantization interval is optimized. Numerical results validate the effectiveness of the proposed scheme.
Autors: Jianyu Wang;Yuan Shen;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1629 - 1632
Publisher: IEEE
 
» On the Diversity of Hybrid Narrowband-PLC/Wireless Communications for Smart Grids
Abstract:
Narrowband powerline communications (NB-PLC) and unlicensed wireless communications are two leading communications technologies for the emerging smart grid applications. The channel and noise statistics experienced by powerline and wireless transmissions are independent and of a non-identical nature. In this paper, we exploit the diversity provided by the simultaneous transmission of the same information signal over powerline and wireless links to enhance the overall system reliability. In particular, we propose efficient techniques to combine the received signals of the NB-PLC and wireless links for both coherent and differential modulation schemes while considering the impulsive nature of the noise on both links. In addition, we derive closed-form expressions for the average bit-error-rate of the proposed combining techniques. Furthermore, we present simulation results that quantify the performance gains achieved by our proposed receive diversity combining techniques compared with conventional combining techniques.
Autors: Mostafa Sayed;Theodoros A. Tsiftsis;Naofal Al-Dhahir;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4344 - 4360
Publisher: IEEE
 
» On the DoF Region of the MIMO Gaussian Two-User Interference Channel With an Instantaneous Relay
Abstract:
This paper studies inner and outer bounds on the degrees of freedom (DoF) region of the multi-antenna two-user Gaussian interference channel with an instantaneous relay (IR) or relay without delay. It is assumed that the two transmitters and the two receivers have antennas, while the IR receives through antennas and transmits through antennas. In the proposed achievable scheme, which generalizes a known one for the case to any , the IR performs memoryless linear operations on its received signal so as to neutralize interference at the receivers, and the beamforming matrices used by the IR and the transmitters are jointly designed. This joint design strictly outperforms known achievable schemes. Two outer bounds are derived. An information theoretic outer bound is obtained by giving the receivers or the IR genie side information, so that the DoF region of the resulting enhanced channel is known; this converse is valid for any type of processing at the IR and shows the optimality of the proposed achievable scheme for some . A linear processing outer bound is obtained when the IR is restricted to performs linear operations, without any memoryless restriction, on its received signal and shows the optimality of the proposed achievable scheme among all linear processing schemes at the IR. As a result of independent interest, the DoF region of the classical multi-antenna two-user Gaussian interference channel without relay when the channel matrices can have any structure is also derived, which generalized available DoF region results that were derived under certain assumptions on the structure of the channel matrices.
Autors: Tang Liu;Daniela Tuninetti;Sae-Young Chung;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4453 - 4471
Publisher: IEEE
 
» On the General Analysis of Coordinated Regularized Zero-Forcing Precoding: An Application to Two-Tier Small-Cell Networks
Abstract:
General analysis of expected per-terminal signal-to-interference-plus-noise-ratio (SINR) and ergodic per-cell sum spectral efficiency for a multi-cellular system with coordinated regularized zero-forcing (RZF) precoding is presented. An application to two-tier small-cell networks is considered, assuming independent and identically distributed (i.i.d.) and semi-correlated Rayleigh fading channels, with spatial correlation at the base station. Our analysis caters for equal and unequal correlation matrices for each terminal. For the i.i.d. case and when each terminal is assigned an equal correlation matrix, our expressions are averaged over the eigenvalue densities of the channel correlation matrices, which follow an uncorrelated and correlated complex central Wishart distribution. With unequal correlation matrices, we exploit the high signal-to-noise-ratio (SNR) convergence of RZF precoding to zero-forcing (ZF) precoding and use a second-order Neumann series expansion to derive closed-form approximations to the expected RZF SINR and ergodic sum spectral efficiency, via the expected ZF SNR and ergodic sum spectral efficiency. Our numerical results show the adverse effects of intercellular interference, along with the improvements in the above-mentioned performance metrics with network-wide coordination over cell-wide and macro-only coordination strategies. The derived expressions are robust to changes in system dimensions, operating SNRs, and correlation levels.
Autors: Harsh Tataria;Peter J. Smith;Pawel A. Dmochowski;
Appeared in: IEEE Transactions on Communications
Publication date: Jul 2017, volume: 65, issue:7, pages: 3133 - 3150
Publisher: IEEE
 
» On the Interpolation of Electromagnetic Near Field Without Prior Knowledge of the Radiating Source
Abstract:
A method is proposed to interpolate the electromagnetic near field when no information on the radiating source is available. In the absence of a priori knowledge, general properties of the electromagnetic field are exploited to estimate the field, namely, the minimum complexity of the field, and the continuity of the first derivatives. These properties are enforced by minimizing the nuclear norm and using the thin plate spline interpolation results, respectively. The proposed procedure is validated experimentally by interpolating the planar electrical near field radiated by three antennas. The quality of the interpolation and its robustness to noise are investigated. Despite its simplicity, the interpolation method is able to properly estimate the near field from a random coarse sampling of . The quality of the near-field interpolation is also confirmed by deriving the far-field. These promising results pave the way for the development of fast antenna measurement procedures.
Autors: Benjamin Fuchs;Laurent Le Coq;Marco Donald Migliore;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3568 - 3574
Publisher: IEEE
 
» On the Interrelation of Security, QoS, and Safety in Cooperative ITS
Abstract:
Cooperative intelligent transport system (C-ITS) is an emerging technology that enables secure and safe road travel using wireless communications. Vehicles regularly share their mobility information with the neighborhood road traffic and infrastructure-based road side units using cooperative awareness messages (CAMs) to develop a local dynamic map for safety applications. Since the applications provided by C-ITS are related to human safety, reliable as well as secure communications are required. To protect the vehicular network from untrusted data of malicious users that could cause network congestion and reduce vehicle safety, ITS standards have proposed various security procedures. In this paper, we analyze the interrelation between security, quality of service (QoS), and safety awareness of vehicles in C-ITS. To formulate an accurate measure of vehicle safety awareness, we first propose novel vehicle and infrastructure centric metrics that use the number of received CAMs, their accuracy, safety importance, and vehicle heading. We then implement the standard CAM signature and verification procedure in the ITS standard. Using simulation results and our proposed metrics, we show the impact of security signature and verification speed on the level of vehicle awareness and, hence, QoS in different road traffic conditions.
Autors: Muhammad Awais Javed;Elyes Ben Hamida;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Jul 2017, volume: 18, issue:7, pages: 1943 - 1957
Publisher: IEEE
 
» On the Meta Distribution of Coverage Probability in Uplink Cellular Networks
Abstract:
This letter studies the meta distribution of coverage probability (CP), within a stochastic geometry framework, for cellular uplink transmission with fractional path-loss inversion power control. Using the widely accepted Poisson point process (PPP) for modeling the spatial locations of base stations (BSs), we obtain the percentiles of users that achieve a target uplink CP over an arbitrary, but fixed, realization of the PPP. To this end, the effect of the users activity factor () and the path-loss compensation factor () on the uplink performance are analyzed. The results show that decreasing and/or increasing reduce the CP variation around the spatially averaged value.
Autors: Hesham ElSawy;Mohamed-Slim Alouini;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1625 - 1628
Publisher: IEEE
 
» On the Optimal Boolean Function for Prediction Under Quadratic Loss
Abstract:
Suppose is obtained by observing a uniform Bernoulli random vector through a binary symmetric channel. Courtade and Kumar asked how large the mutual information between and a Boolean function could be, and conjectured that the maximum is attained by a dictator function. An equivalent formulation of this conjecture is that dictator minimizes the prediction cost in a sequential prediction of under logarithmic loss, given . In this paper, we study the question of minimizing the sequential prediction cost under a different (proper) loss function—the quadratic loss. In the noiseless case, we show that majority asymptotically minimizes this prediction cost among all Boolean functions. We further show that for weak noise, majority is better than a dictator, and that for a strong noise dictator outperforms majority. We conjecture that for quadratic loss, there is no single sequence of Boolean functions that is simultaneously (asymptotically) optimal at all noise levels.
Autors: Nir Weinberger;Ofer Shayevitz;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4202 - 4217
Publisher: IEEE
 
» On the Optimality of Power Allocation for NOMA Downlinks With Individual QoS Constraints
Abstract:
This letter investigates a power allocation problem in a downlink single-input single-output non-orthogonal multiple access (NOMA) system. Our goal is to maximize the sum rate of users subject to minimum user rate requirements. We rigorously prove the optimal user decoding order, and show that the sum rate maximization problem is convex, which guarantees the globally optimal solution. Numerical results validate the performance gain by the proposed NOMA compared with conventional schemes.
Autors: Zhaohui Yang;Wei Xu;Cunhua Pan;Yijin Pan;Ming Chen;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1649 - 1652
Publisher: IEEE
 
» On the Performance Limits of Cooperative Localization in Wireless Sensor Networks With Strong Sensor Position Uncertainty
Abstract:
Position information is crucial for diverse applications in wireless sensor networks (WSNs). In this letter, we study performance limits of anchorless cooperative localization in WSNs with strong sensor position uncertainty. Based on an approximated Cramér–Rao bound decomposition, we are able to show that the average localization performance of a network is largely determined by the number of agents and the signal metric employed rather than the network topology. Some properties of the proposed approximation, including its behavior in extended and dense networks and the performance bound of individual agents, are further analyzed. Finally, numerical results are used to verify our analysis.
Autors: Yifeng Xiong;Nan Wu;Hua Wang;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1613 - 1616
Publisher: IEEE
 
» On the Performance of the Intel SR30 Depth Camera: Metrological and Critical Characterization
Abstract:
Specifically conceived for applications related to face analytics and tracking, scene segmentation, hand/finger tracking, gaming, augmented reality, and RGB-D cameras are nowadays used even as 3-D scanners. Despite depth cameras’ accuracy and precision are not comparable with professional 3-D scanners, they still constitute a promising device for reverse engineering (RE) applications in the close range, due to their low cost. This is particularly true for more recent devices, such as, for instance, the RealSense SR300, which promises to be among the best performing close range depth cameras in the market. Given the potentiality of this new device, and since to date a deep investigation on its performances has not been assessed in scientific literature, the main aim of this paper is to characterize and to provide metrological considerations on the Intel RealSense SR300 depth sensor when this is used as a 3-D scanner. To this end, the device sensor performances are first assessed by applying the existing normative guidelines (i.e. the one published by the Association of German Engineers - Verein Deutscher Ingenieure - VDI/VDE 2634) both to a set of raw captured depth data and to a set acquired with optimized setting of the camera. Then, further assessment of the device performances is carried out by applying some strategies proposed in the literature using optimized sensor setting, to reproduce “real life” conditions for the use as a 3-D scanner. Finally, the performance of the device is critically compared against the performance of latest short-range sensors, thus providing a useful guide, for researchers and practitioners, in an informed choice of the optimal device for their own RE application.
Autors: Monica Carfagni;Rocco Furferi;Lapo Governi;Michaela Servi;Francesca Uccheddu;Yary Volpe;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4508 - 4519
Publisher: IEEE
 
» On the Probability That All Eigenvalues of Gaussian, Wishart, and Double Wishart Random Matrices Lie Within an Interval
Abstract:
We derive the probability that all eigenvalues of a random matrix M lie within an arbitrary interval , , when M is a real or complex finite-dimensional Wishart, double Wishart, or Gaussian symmetric/Hermitian matrix. We give efficient recursive formulas allowing the exact evaluation of for Wishart matrices, even with a large number of variates and degrees of freedom. We also prove that the probability that all eigenvalues are within the limiting spectral support (given by the Marčenko-Pastur or the semicircle laws) tends for large dimensions to the universal values 0.6921 and 0.9397 for the real and complex cases, respectively. Applications include improved bounds for the probability that a Gaussian measurement matrix has a given restricted isometry constant in compressed sensing.
Autors: Marco Chiani;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4521 - 4531
Publisher: IEEE
 
» On the Robustness of Spatial Modulation to I/Q Imbalance
Abstract:
We analyze the bit error rate performance of spatial modulation (SM)-based direct-conversion transceivers under transmit in-phase/quadrature (I/Q) imbalance. To investigate the impact of transmit I/Q imbalance on SM, we derive the signal-to-noise ratio loss due to I/Q imbalance impact compared with an ideal direct-conversion transceiver with no I/Q imbalance. Our analysis unveils the robustness of SM to transmit I/Q imbalance compared with conventional single-input multi-output transmissions, by relying more on the spatial domain.
Autors: Ahmed G. Helmy;Marco Di Renzo;Naofal Al-Dhahir;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1485 - 1488
Publisher: IEEE
 
» On the Spectral Efficiency and Security Enhancements of NOMA Assisted Multicast-Unicast Streaming
Abstract:
This paper considers the application of non-orthogonal multiple access (NOMA) to a multi-user network with mixed multicasting and unicasting traffic. The proposed design of beamforming and power allocation ensures that the unicasting performance is improved while maintaining the reception reliability of multicasting. Both analytical and simulation results are provided to demonstrate that the use of the NOMA assisted multicast-unicast scheme yields a significant improvement in spectral efficiency compared with orthogonal multiple access (OMA) schemes which realize multicasting and unicasting services separately. Since unicast messages are broadcast to all the users, how the use of NOMA can prevent those multicast receivers intercepting the unicasting messages is also investigated, where it is shown that the secrecy unicasting rate achieved by NOMA is always larger than or equal to that of OMA. Simulation results are provided to verify the developed analytical results and demonstrate the superior performance of the proposed NOMA scheme.
Autors: Zhiguo Ding;Zhongyuan Zhao;Mugen Peng;H. Vincent Poor;
Appeared in: IEEE Transactions on Communications
Publication date: Jul 2017, volume: 65, issue:7, pages: 3151 - 3163
Publisher: IEEE
 
» On the Universality of Jordan Centers for Estimating Infection Sources in Tree Networks
Abstract:
Finding the infection sources in a network when we only know the network topology and infected nodes, but not the rates of infection, is a challenging combinatorial problem, and it is even more difficult in practice where the underlying infection spreading model is usually unknown a priori. In this paper, we are interested in finding a source estimator that is applicable to various spreading models, including the susceptible–infected (SI), susceptible–infected–recovered (SIR), susceptible–infected–recovered–infected (SIRI), and susceptible–infected–susceptible (SIS) models. We show that under the SI, SIR, and SIRI spreading models and with mild technical assumptions, the Jordan center is the infection source associated with the most likely infection path in a tree network with a single infection source. This conclusion applies for a wide range of spreading parameters, while it holds for regular trees under the SIS model with homogeneous infection and recovery rates. Since the Jordan center does not depend on the infection, recovery, and reinfection rates, it can be regarded as a universal source estimator. We also consider the case where there are infection sources, generalize the Jordan center definition to a -Jordan center set, and show that this is an optimal infection source set estimator in a tree network for the SI model. Simulation results on various general synthetic networks and real-world networks suggest that Jordan center-based estimators consistently outperform the betweenness, closeness, distance, degree, eigenvector, and pagerank centrality-based heuristics, even if the network is not a tree.
Autors: Wuqiong Luo;Wee Peng Tay;Mei Leng;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4634 - 4657
Publisher: IEEE
 
» On \"Flipping\" a Large Signal Processing Class [SP Education]
Abstract:
Modern academy traces its roots back to the medieval universities established between the 12th and the 14th centuries [1]. Much has changed in the world of academia during the millennium that separates a modern university from a medieval one.
Autors: Waheed U. Bajwa;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jul 2017, volume: 34, issue:4, pages: 158 - 170
Publisher: IEEE
 
» On-Chip Electronic Nose For Wine Tasting: A Digital Microfluidic Approach
Abstract:
This paper presents the integration of a metal oxide gas sensor into an open digital microfluidic (DMF) system for rapid identification of different types of wines. The effect of water-cross sensitivity of a gas sensor was eliminated using a hydrophobic porous micro-channel, which provides selective detection of the aromas of a wine droplet manipulated on a DMF platform. Seven different kinds of wines are tested and successfully recognized. The temporal responses of the sensor to a droplet of each of these wines are reported. Two features are extracted from the transient response and mapped into a 2-D plot to show the segregation of different wines.
Autors: Mohammad Paknahad;Ali Ahmadi;Jacques Rousseau;Hojatollah Rezaei Nejad;Mina Hoorfar;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4322 - 4329
Publisher: IEEE
 
» On-Orbit Geometric Calibration Using a Cross-Image Pair for the Linear Sensor Aboard the Agile Optical Satellite
Abstract:
Due to the limitations in the geometric accuracy of reference data and matching accuracy between images from different sensors, the conventional method of calibration may not perform well in terms of accuracy for an agile optical satellite (AOS) with submeter resolution. Due to the high mobility of an AOS, a cross-image pair (CIP) including a push-broom image and a swing scanning image for the same area could be collected. This letter developed a novel calibration method for an AOS, which is characterized using the constraints from the CIP instead of reference images covering a calibration site. In this method, the viewing angle of a charge-coupled device detector fit by two polynomials is introduced into a rigorous imaging model to establish the calibration model, and a bundle adjustment under the constraint of an aided digital surface model (DSM) is applied to solve the unstable calculation stemming from the strong correlation between the parameters of the coupled images. To verify the effectiveness of the method, experiments were conducted using the CIP simulated according to the rigorous imaging process of an AOS. In tests, the method achieved a high theoretical accuracy of better than 0.1 pixels.
Autors: Ying-Dong Pi;Bo Yang;Mi Wang;Xin Li;Yu-Feng Cheng;Wen-Li Tang;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jul 2017, volume: 14, issue:7, pages: 1176 - 1180
Publisher: IEEE
 
» Online and Efficient Fabrication of Helical Long-Period Fiber Gratings
Abstract:
By taking the advantage of inherent core-cladding eccentricities in standard single-mode fibers, in this letter, we propose and demonstrate an efficient method to fabricate helical long-period fiber gratings (H-LPFGs) by directly twisting fibers. In the fabrication process, we use a double-beam CO2 laser for heating the fiber stably and uniformly, together with an online scheme for monitoring the spectrum. Compared with other fabrication methods reported, the quality of H-LPFGs we fabricated is improved significantly, showing a high extinction ratio of over 30 dB and a low insertion loss of ~1 dB. Based on the fact that H-LPFGs with different pitches for specific mode couplings can be fabricated efficiently and controllably, to the best of our knowledge, we actually achieve H-LPFGs with the highest quality up to now, which may find important applications, such as filtering, sensing, and optical vortex generation.
Autors: Kaili Ren;Liyong Ren;Jian Liang;Xudong Kong;Haijuan Ju;Zhaoxin Wu;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jul 2017, volume: 29, issue:14, pages: 1175 - 1178
Publisher: IEEE
 
» Online Detection of Low-Quality Synchrophasor Measurements: A Data-Driven Approach
Abstract:
In this paper, an online data-driven approach is proposed for the detection of low-quality synchrophasor measurements. The proposed method leverages the spatio-temporal similarities among multiple-time-instant synchrophasor measurements and formulates the low-quality synchrophasor data as spatio-temporal outliers. A density-based local outlier detection technique is proposed to detect the spatio-temporal outliers. This data-driven approach involves no system modeling information. The detection algorithm can operate under both normal and fault-on system conditions, with fast computation speed suitable for online applications. Case studies on both synthetic and real-world synchrophasor data verify the effectiveness of the proposed approach.
Autors: Meng Wu;Le Xie;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 2817 - 2827
Publisher: IEEE
 
» Online Measurement-Based Adaptive Scalable Video Transmission in Energy Harvesting Aided Wireless Systems
Abstract:
We consider the point-to-point adaptive transmission of scalable video coding streams over a fading channel in energy harvesting (EH) aided communication systems, where the transmitter is equipped with an EH device and a rechargeable battery. The aim of this paper is to enable the transmitter having the ability of adaptively adjusting the number of video layers to be transmitted according to the available energy. Since the depletion of the energy in the battery acts as a trigger for the interruption of the video transmission, we define the energy starvation probability for equivalently characterizing a quality-of-experience (QoE) metric. We formulate the problem of EH-aided video transmission as a constrained optimization problem, maximizing the number of video layers for transmission while keeping the energy starvation probability below a threshold. Classic large deviation theory is invoked for estimating the energy starvation probability from online measurements. Consequently, our dynamic layer switch algorithm operates with no prior statistical knowledge of both the EH process and of the channel quality. Furthermore, the technique of perturbation analysis that constructs a perturbed sample path from an original sample path is invoked for improving the performance of the proposed method. Our experimental results verify that the algorithms proposed have the adaptation capability to accommodate both the energy-dynamics and the channel-dynamics for improving the video quality subject to an unobjectionable level of transmission interruption rate.
Autors: Jian Yang;Weizhe Cai;Yongyi Ran;Hongsheng Xi;Lajos Hanzo;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 6231 - 6245
Publisher: IEEE
 
» Online Transfer Learning with Multiple Homogeneous or Heterogeneous Sources
Abstract:
Transfer learning techniques have been broadly applied in applications where labeled data in a target domain are difficult to obtain while a lot of labeled data are available in related source domains. In practice, there can be multiple source domains that are related to the target domain, and how to combine them is still an open problem. In this paper, we seek to leverage labeled data from multiple source domains to enhance classification performance in a target domain where the target data are received in an online fashion. This problem is known as the online transfer learning problem. To achieve this, we propose novel online transfer learning paradigms in which the source and target domains are leveraged adaptively. We consider two different problem settings: homogeneous transfer learning and heterogeneous transfer learning. The proposed methods work in an online manner, where the weights of the source domains are adjusted dynamically. We provide the mistake bounds of the proposed methods and perform comprehensive experiments on real-world data sets to demonstrate the effectiveness of the proposed algorithms.
Autors: Qingyao Wu;Hanrui Wu;Xiaoming Zhou;Mingkui Tan;Yonghui Xu;Yuguang Yan;Tianyong Hao;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jul 2017, volume: 29, issue:7, pages: 1494 - 1507
Publisher: IEEE
 
» Online Unbalanced Rotor Fault Detection of an IM Drive Based on Both Time and Frequency Domain Analyses
Abstract:
An effective maintenance program provides incipient fault detection of rotating machines which reduces interim, unscheduled, and excessive maintenance actions. By applying suitable online condition monitoring accompanied with signal processing techniques, machines' irregularity can be detected at an early stage. Therefore, this paper presents an online condition monitoring based fault detection of an unbalanced rotor induction motor (IM). Characteristic features of motor current and vibration signals are analyzed in time domain as a fault diagnosis technique, which is a key parameter to the fault threshold. Motor current and vibration signals are analyzed based on fast Fourier transform (FFT), Hilbert transform, envelope detection, and discrete wavelet transform (DWT) to detect the severity of the fault and its possible location under different load conditions. The DWT is used to extract the information from a signal over a wide range of frequencies. The Daubechies wavelet is selected for the healthy and faulty condition analysis of IM. It is found that the DWT can more precisely identify the fault as compared to the conventional FFT for a three-phase, two-pole, 0.246 kW, 60 Hz, 2950 r/min IM drive.
Autors: Md. Mizanur Rahman;Mohammad Nasir Uddin;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 4087 - 4096
Publisher: IEEE
 
» Open and Closed-Loop Residential Load Models for Assessment of Conservation Voltage Reduction
Abstract:
This paper presents a modeling approach for capturing closed-loop load behavior in distribution networks using bottom-up time-variant load models and incorporating load-flow feedback for thermal loads. Traditional load models are useful for providing insights into instantaneous changes in power, however, they do not capture the time-variant response to changes in voltage due to the effects of appliances with closed-control loops such as those which are thermostatically controlled. This paper proposes a modeling and co-simulation platform to simulate closed-loop load-modeling using state-of-the-art bottom-up load modeling techniques for the residential sector with a feedback model for time series steady-state load-flow. It incorporates time-variant load models and discrete state-space representation of thermostatically controlled appliances. The developed methodology is used in a conservation voltage reduction case study on an urban distribution network, allowing detailed assessment of the voltage response and analysis of changes in active and reactive power and network losses.
Autors: Killian McKenna;Andrew Keane;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 2995 - 3005
Publisher: IEEE
 
» Operational Reliability and Economics of Power Systems With Considering Frequency Control Processes
Abstract:
With high renewable power penetration, uncertainty and intermittence of renewable sources become major concerns of power system planning and operation. Large and fast wind speed change may cause great variation of active power generation, which may lead to system stability and reliability problems. The response speeds of the committed conventional generators (CGs) for frequency regulations are critical for system reliable and stable operation. The slow response of the committed CGs may result in power shortage or surplus, which may affect system frequency. This paper proposes a technique to evaluate operational reliability and efficiency problems of power systems with high wind power penetration from frequency aspect. Energy unnecessarily consumed and less supplied during system frequency control processes are modeled in detail. The reliability and economic indexes are formulated with considering system dynamic frequency control processes. The IEEE-RTS79 is used to verify the proposed models and method.
Autors: Chen Liang;Peng Wang;Xiaoqing Han;Wenping Qin;Roy Billinton;Wenyuan Li;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 2570 - 2580
Publisher: IEEE
 
» Optical Power Efficiency Versus Breakdown Voltage of Avalanche-Mode Silicon LEDs in CMOS
Abstract:
We report on the dependency of the optical power efficiency on the breakdown voltage of avalanche-mode (AM) light-emitting diodes (LEDs) in silicon. Lateral p+-n-n+ LEDs have been designed in a 65-nm bulk CMOS technology, where is varied between 2 and 9 V. This tunes both the magnitude and the spatial distribution of the reverse electric field, which governs AM electroluminescence. Experiments show that a maximum of is obtained for V. For V, non-local avalanche results in a lower , while for V, a gradual reduction in with increasing is obtained. This trend is compared with two recently proposed opto-electronic models. A maximum in at relatively low voltages is attractive for monolithic opto-electronic integration in silicon
Autors: Satadal Dutta;Gerard J. M. Wienk;Raymond J. E. Hueting;Jurriaan Schmitz;Anne-Johan Annema;
Appeared in: IEEE Electron Device Letters
Publication date: Jul 2017, volume: 38, issue:7, pages: 898 - 901
Publisher: IEEE
 
» Optical Stimulation Effects on TiO2 Sensor Dielectric Used in Capacitively-Coupled High-Density CMOS Microelectrode Array
Abstract:
The effect of optical stimulation of neural tissue is considered in capacitively coupled CMOS microelectrode arrays used for in vitro extracellular recording from neural tissue. Using a 25-nm high-k TiO2 sensor dielectric with 20% ZrO2, light-induced currents through the dielectric are found at short wavelengths within the visible and relevant spectrum for the above-mentioned purpose. Purely capacitive behavior is obtained for green light and longer wavelength, leakage-induced artifacts at shorter wavelengths are avoided by using optimized operating conditions of recording sites and entire system.
Autors: Gabriel Bertotti;Florian Jetter;Stefan Keil;Normal Dodel;Matthias Schreiter;Dirk Wolansky;Clemens Boucsein;Karl-Heinz Boven;Günther Zeck;Roland Thewes;
Appeared in: IEEE Electron Device Letters
Publication date: Jul 2017, volume: 38, issue:7, pages: 967 - 970
Publisher: IEEE
 
» Optically Invisible Antenna Integrated Within an OLED Touch Display Panel for IoT Applications
Abstract:
Future electronics and Internet of Things devices with the capability of high-speed wireless communication will increasingly rely on efficient and intelligent antennas. However, conventional wireless communication systems for small wireless electronics devices suffer from low radiation efficiencies of miniaturized antennas implemented within less-than ideal locations and real estates. Here, we introduce the original concept of utilizing the entire transparent region of high-resolution organic light-emitting diode (OLED) touch displays to render an antenna that is invisible to the human eye. A transverse magnetic resonant mode antenna is formulated based on transparent conductive polymers, which are precisely realized using mesoscale formation of electromagnetic boundary conditions. Simultaneously, these electromagnetic patterns achieve optical invisibility. We show that the transparent antenna film can be integrated inside an OLED touch display and feature efficient radiation properties at 2.4 GHz. The presented theory and measurement studies of the fabricated prototype for smartwatch application for Wi-Fi and Bluetooth connectivity inspire a broader range of integration of microwave and display technologies.
Autors: Wonbin Hong;Sangho Lim;Seungtae Ko;Yoon Geon Kim;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3750 - 3755
Publisher: IEEE
 
» Optimal and Near-Optimal Detection in Bursty Impulsive Noise
Abstract:
In many practical scenarios, the ambient noise process is known to be impulsive. To combat this, several robust measures have been proposed in the literature. Most of them assume white noise processes, i.e., the noise samples are independent and identically distributed heavy-tailed random variables. However, noise is seldom white in practice and therefore exhibits memory. For impulsive noise, dependency among samples results in outliers clustering together. The process is thus impulsive and bursty. In our work, we employ stationary -sub-Gaussian noise with memory order (SGN( )) to model bursty impulsive noise. The model is based on the multivariate -sub-Gaussian (SG) distribution family and statistically characterizes adjacent samples from elliptical distributions. The latter assumption holds well for snapping shrimp noise found in warm shallow underwater channels. We investigate the performance of conventional robust detectors in SGN() and also propose novel near-optimal detectors. The Neyman–Pearson (NP) approach for binary hypothesis testing is considered and extensive simulation results for the aforementioned detectors are offered. For all instances, we employ an SGN() proces- whose parameters are tuned to snapping shrimp noise data sets. By incorporating good signal design rules, it is shown that there is a large performance gap between the new and conventional detectors in various impulsive regimes. Moreover, it is possible to derive a near-optimal detector if one only has information of the temporal statistics of the noise process.
Autors: Ahmed Mahmood;Mandar Chitre;
Appeared in: IEEE Journal of Oceanic Engineering
Publication date: Jul 2017, volume: 42, issue:3, pages: 639 - 653
Publisher: IEEE
 
» Optimal Construction of Regenerating Code Through Rate-Matching in Hostile Networks
Abstract:
Regenerating code is a class of distributed storage codes that can optimally trade the bandwidth required to repair a failed node with the amount of data stored per node. There are two optimal points in the regeneration tradeoff curve: the minimum storage regeneration code and the minimum bandwidth regeneration code. However, in hostile networks where the storage nodes may be compromised, the storage capacity of the network can be significantly affected. In this paper, we propose two optimal regenerating code constructions through rate-matching to combat this kind of adversarial attacks in hostile networks. We first develop a two-layer rate-matched regenerating code construction. By matching the parameters of the full rate code and the partial rate code, we can optimize the overall storage efficiency while maintaining the corrupted node detection probability. Through comprehensive analysis, we show that the two-layer rate-matched regenerating code can achieve 70% higher storage efficiency than the universally resilient regenerating code. We then propose an optimal -layer regenerating code construction. While the principle remains the same as the two-layer code, it is designed to optimize the total number of detectable corrupted nodes of layers from which the errors can be corrected under the constraint of any given code efficiency. Compared with the universally resilient regenerating code with the same rate, our -layer code can detect 50% more corrupted nodes.
Autors: Jian Li;Tongtong Li;Jian Ren;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4414 - 4429
Publisher: IEEE
 
» Optimal Content Placement for Wireless Femto-Caching Network
Abstract:
This paper investigates optimal content placement for wireless femto-caching network. The average bit error rate (BER) is formulated as a function of content placement under wireless fading. To minimize the average BER, we propose a greedy algorithm finding optimal content placement with low-computational complexity. Exploiting the property of the optimal content placement which we derive, the proposed algorithm can be performed over considerably reduced search space. Contrary to the optimal content placement without consideration of wireless fading aspects, we reveal that optimal content placement can be reached by balancing a tradeoff between two different gains: file diversity gain and channel diversity gain. Moreover, we also identify the conditions that the optimal placement can be found without running the proposed greedy algorithm and derive the corresponding optimal content placement in closed form.
Autors: Jaeyoung Song;Hojin Song;Wan Choi;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4433 - 4444
Publisher: IEEE
 
» Optimal Device-Aware Caching
Abstract:
Caches in Content-Centric Networks (CCN) are increasingly adopting flash memory based storage. The current flash cache technology stores all files with the largest possible “expiry date,” i.e., the files are written in the memory so that they are retained for as long as possible. This, however, does not leverage the CCN data characteristics where content is typically short-lived and has a distinct popularity profile. Writing files in a cache using the longest retention time damages the memory device thus reducing its lifetime. However, writing using a small retention time can increase the content retrieval delay, since, at the time a file is requested, the file may already have been expired from the memory. This motivates us to consider a joint optimization wherein we obtain optimal policies for jointly minimizing the content retrieval delay (which is a network-centric objective) and the flash damage (which is a device-centric objective). Caching decisions now not only involve what to cache but also for how long to cache each file. We design provably optimal policies and numerically compare them against prior policies.
Autors: Samta Shukla;Alhussein A. Abouzeid;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jul 2017, volume: 16, issue:7, pages: 1994 - 2007
Publisher: IEEE
 
» Optimal Dynamic Multicast Scheduling for Cache-Enabled Content-Centric Wireless Networks
Abstract:
Caching and multicasting at base stations are two promising approaches to support massive content delivery over wireless networks. However, existing scheduling designs do not fully exploit the advantages of the two approaches. In this paper, we consider the optimal dynamic multicast scheduling to jointly minimize the average delay, power, and fetching costs for cache-enabled content-centric wireless networks. We formulate this stochastic optimization problem as an infinite horizon average cost Markov decision process (MDP).By using relative value iteration and special structures of the request queue dynamics, we analyze the properties of the value function and the state-action cost function of the MDP for both the uniform and nonuniform channel cases. Based on these properties, we show that the optimal policy, which is adaptive to the request queue state, has a switch structure in the uniform case and a partial switch structure in the nonuniform case. Moreover, in the uniform case with two contents, we show that the switch curve is monotonically non-decreasing. Motivated by the switch structures of the optimal policy, we propose a low-complexity suboptimal policy, which exhibits similar switch structures to the optimal policy, and design a low-complexity algorithm to compute this policy.
Autors: Bo Zhou;Ying Cui;Meixia Tao;
Appeared in: IEEE Transactions on Communications
Publication date: Jul 2017, volume: 65, issue:7, pages: 2956 - 2970
Publisher: IEEE
 
» Optimal Location-Allocation of TCSCs and Transmission Switch Placement Under High Penetration of Wind Power
Abstract:
We propose a stochastic mathematical program for finding the optimal location and compensation level of thyristor-controlled series compensators (TCSCs) and the optimal location of line switches in a transmission network. The combined uncertainty of the load and generation is captured by scenarios. The proposed problem has polynomial constraints, and we use the general linearization technique to linearize those constraints. The model becomes decomposable into a primal master and subprograms solvable by a branch-and-price procedure with the aid of column generation. The numerical results of implementing the model for the IEEE 118-bus test system show that combined investment in TCSCs and switches decreased the cost of energy and increased the penetration of wind energy more than individual investment of TCSCs or switches.
Autors: Omid Ziaee;Fred Choobineh;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 3006 - 3014
Publisher: IEEE
 
» Optimal Mass Transport: Signal processing and machine-learning applications
Abstract:
Transport-based techniques for signal and data analysis have recently received increased interest. Given their ability to provide accurate generative models for signal intensities and other data distributions, they have been used in a variety of applications, including content-based retrieval, cancer detection, image superresolution, and statistical machine learning, to name a few, and they have been shown to produce state-of-the-art results. Moreover, the geometric characteristics of transport-related metrics have inspired new kinds of algorithms for interpreting the meaning of data distributions. Here, we provide a practical overview of the mathematical underpinnings of mass transport-related methods, including numerical implementation, as well as a review, with demonstrations, of several applications. Software accompanying this article is available from [43].
Autors: Soheil Kolouri;Se Rim Park;Matthew Thorpe;Dejan Slepcev;Gustavo K. Rohde;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jul 2017, volume: 34, issue:4, pages: 43 - 59
Publisher: IEEE
 
» Optimal Policies for Brownian Inventory Systems With a Piecewise Linear Ordering Cost
Abstract:
We consider a stochastic inventory system with general piecewise linear ordering cost. The cumulative demand is modeled as a Brownian motion process. The ordering cost function is neither convex nor concave; it may not be monotone; and it is not even necessarily continuous, and it includes most ordering cost functions studied in the literature, e.g., economies-of-scale or dis-economies of scale, all-unit discount or incremental discount, and multiple setup costs, as special cases. In addition to ordering cost, the system incurs the usual holding/shortage cost, and the objective is to minimize the average system cost per unit of time. Despite the complexity in the ordering cost function, we show that an optimal control policy is very simple: it is either an policy or a one-sided singular control policy.
Autors: Dacheng Yao;Xiuli Chao;Jingchen Wu;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3235 - 3248
Publisher: IEEE
 
» Optimal Power Control in Ultra-Dense Small Cell Networks: A Game-Theoretic Approach
Abstract:
In this paper, we study the power control problem for interference management in the ultra-dense small cell networks, which is formulated to maximize the sum-rate of all the small cells while keeping tolerable interference to the macrocell users. We investigate the problem by proposing a novel game with dynamic pricing. Theoretically, we prove that the Nash equilibrium (NE) of the formulated game coincides with the stationary point of the original sum-rate maximization problem, which could be locally or globally optimal. Furthermore, we propose a distributed iterative power control algorithm to converge to the NE of the game with guaranteed convergence. To reduce the information exchange and computational complexity, we propose an approximation model for the original optimization problem by constructing the interfering domains, and accordingly design a local information-based iterative algorithm for updating each small cell’s power strategy. Theoretic analysis shows that the local information-based power control algorithm can converge to the NE of the game, which corresponds to the stationary point of the original sum-rate maximization problem. Finally, simulation results demonstrate that the proposed approach yields a significant transmission rate gain, compared with the existing benchmark algorithms.
Autors: Jianchao Zheng;Yuan Wu;Ning Zhang;Haibo Zhou;Yueming Cai;Xuemin Shen;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4139 - 4150
Publisher: IEEE
 
» Optimal Radix-2 FFT Compatible Filters for GFDM
Abstract:
For a linear waveform, a finite condition number of the corresponding modulation matrix is necessary for the waveform to convey the message without ambiguity. Based on the Zak transform, this letter presents an analytical approach to compute the condition number of the modulation matrix for the multi-carrier waveform generalized frequency division multiplexing (GFDM). We further propose a filter design that yields non-singular modulation matrices for an even number of subcarriers and subsymbols, which is not achievable for any previous work. Such a new design has a significant impact on implementation complexity, as the radix-2 FFT operations for conventional multicarrier waveforms can readily be employed for GFDM. Also, we analytically derive the optimal filter that minimizes the condition number. We numerically evaluate the signal-to-interference ratio (SIR) and noise-enhancement factor (NEF) for matched filter (MF) and zero-forcing (ZF) GFDM receivers for the proposed design, respectively.
Autors: Ahmad Nimr;Maximilian Matthé;Dan Zhang;Gerhard Fettweis;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1497 - 1500
Publisher: IEEE
 
» Optimal Relay Selection for the Parallel Hybrid RF/FSO Relay Channel: Non-Buffer-Aided and Buffer-Aided Designs
Abstract:
Hybrid radio frequency (RF)/free space optical (FSO) systems are among the candidate enabling technologies for the next generation of wireless networks, since they benefit from both the high data rates of the FSO subsystem and the high reliability of the RF subsystem. In this paper, we focus on the problem of throughput maximization in the parallel hybrid RF/FSO relay channel. In the parallel hybrid RF/FSO relay channel, a source node sends its data to a destination node with the help of multiple relay nodes. Thereby, for a given relay, the source-relay and the relay-destination FSO links are orthogonal with respect to each other due to the narrow beam employed for FSO transmission, whereas due to the broadcast nature of the RF channel, half-duplex operation is required for the RF links if self-interference is to be avoided. Moreover, we consider the two cases where the relays are and are not equipped with buffers. For both cases, we derive the optimal relay selection policies for the RF and FSO links and the optimal time allocation policy for transmission and reception for the RF links. The proposed optimal protocols provide important insights for an optimal system design. Since the optimal buffer-aided policy introduces an unbounded delay, we also propose a suboptimal buffer-aided policy, which ensures certain target average delays. Moreover, we present distributed implementations for both the proposed optimal protocols. Simulation results demonstrate that a considerable gain can be achieved by the proposed adaptive protocols in comparison with benchmark schemes from the literature.
Autors: Marzieh Najafi;Vahid Jamali;Robert Schober;
Appeared in: IEEE Transactions on Communications
Publication date: Jul 2017, volume: 65, issue:7, pages: 2794 - 2810
Publisher: IEEE
 
» Optimal Thermostat Programming for Time-of-Use and Demand Charges With Thermal Energy Storage and Optimal Pricing for Regulated Utilities
Abstract:
In this paper, we solve the optimal thermostat programming problem for consumers with combined demand ($/kW) and time-of-use ($/kWh) pricing plans. We account for energy storage in interior floors and surfaces by using a partial-differential model of diffusion. We consider two types of thermostats: the first can be programmed to vary continuously in time and the second is limited to four constant set-points. Thermostat settings were constrained to lie within a desired interval. Numerical testing shows that the resulting algorithm can reduce monthly electricity bills by up to 25% in the summer with average savings of 9.2% over a variety of building models by using prices from Arizona utility Salt River Project. Furthermore, we examine how optimal thermostat programming affects optimal electricity pricing by using a simplified model of utility generation costs to determine the optimal ratio of demand to time-of-use prices. Our results show that pricing electricity at the marginal cost of generation in this scenario is suboptimal.
Autors: Reza Kamyar;Matthew M. Peet;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 2714 - 2723
Publisher: IEEE
 
» Optimal Traffic Sensor Location for Origin–Destination Estimation Using a Compressed Sensing Framework
Abstract:
A series of flow estimation problems, especially origin–destination estimation, involves optimally locating sensors on a transportation network to measure traffic counts. As compressed sensing (CS) provides a new method to solve the estimation problem, its sensor location strategy needs to be researched in order to facilitate the reconstruction. This paper first points out that the accurate flow recovery is difficult by introducing a necessary condition, and then categorizes the location determination into two cases: sensor number with restriction and without restriction. For both cases, we elucidate their theoretical foundations of locating methods and propose an algorithm based on column coherence minimization, which optimally facilitates the reconstruction for CS framework. Numerical experiments indicate that the selected sensor locations fit the flow recovery and the proposed algorithm, compared with other methods, can lead to a slightly better result under certain observations.
Autors: Peijun Ye;Ding Wen;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Jul 2017, volume: 18, issue:7, pages: 1857 - 1866
Publisher: IEEE
 
» Optimization of Deployable Base Stations With Guaranteed QoE in Disaster Scenarios
Abstract:
Reconstructing emergency communication networks (ECNs) quickly after a disaster occurs is critical so that people can share information and confirm their safety. In recent studies, deployable base stations (DBSs) have demonstrated their ability to reconstruct an ECN. However, considering limited resources, it is impossible to deploy DBSs in the whole disaster area. The above shortage can be covered by deploying small-cell networks (i.e., low-power transmission base stations) in areas with high communication demand, e.g., in refuges. Considering the above two-tier ECN, in this paper, we study its performance and optimization issue with the objective of minimizing the number/density of DBSs while guaranteeing acceptable coverage probabilities for both communication tiers. The majority of current research focuses on scenarios where the base stations follow a homogeneous Poisson point process of coverage probability. It is difficult to transfer the results to other applications, e.g., when communication resources are shared, such as by refugees following a disaster. In such cases, the distribution of users is closer to that of a Poisson cluster process. We then investigate the optimization method to minimize the number/density of DBSs. We used Monte Carlo methods with various parameter choices to evaluate the results and to determine the accuracy of our evaluation.
Autors: Junbo Wang;Song Guo;Zixue Cheng;Peng Li;Jie Wu;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 6536 - 6552
Publisher: IEEE
 
» Optimization of Electrical Energy Storage System Sizing for an Accurate Energy Management in an Aircraft
Abstract:
The development of More Electrical Aircraft has lead to the adaptation of their electrical architecture and their capacity of power generation and storage. Therefore, generation and storage systems must be well sized to match their energetic performances versus the vehicle requirements. This paper deals with the optimal sizing of storage systems (secondary batteries and supercapacitors) for an aircraft. In this particular application, the global weight of the whole storage system must be minimized. An optimal sizing tool has been developed to reach this objective by acting on setting parameters that are the cut-off frequency of the low-pass filter (to share out the mission profile between storage systems according to an energy management based on a frequency approach), the discharge ratio for storage components (in relation with their technological limits and the electrical network specifications), and temperature (which can be seen as an environmental constraint as well). The optimization results, which are obtained with the simulated annealing method implemented in MATLAB, are presented and assessed throughout the whole temperature range. Finally, the impact of setting parameters on the global storage system weight is studied, and an adaptation of the energy management strategy is presented to take into account the temperature influence on battery performances.
Autors: Pierre Saenger;Nathalie Devillers;Karine Deschinkel;Marie-Cécile Péra;Raphaël Couturier;Frédéric Gustin;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 5572 - 5583
Publisher: IEEE
 
» Optimization of Fusion Kernels on Accelerators with Indirect or Strided Memory Access Patterns
Abstract:
This paper describes optimization for high-dimensional stencil computations on accelerators involving complex memory access patterns, which appear in five dimensional fusion plasma turbulence codes, GYSELA and GT5D. They include different types of memory access patterns, the indirect memory access in GYSELA with a Semi-Lagrangian scheme and the strided memory access in GT5D with a Finite-Difference scheme. We focus on the affinity of the memory access patterns to accelerators such as GPGPUs and Xeon Phi coprocessors. On both devices, the Array of Structure of Array (AoSoA) data layout is preferable for contiguous memory accesses. It is shown that the effective local cache usage by improving spatial and temporal data locality is critical on Xeon Phi. On GPGPU, the texture memory usage improves the performance of the indirect memory accesses in the Semi-Lagrangian scheme. The reuse of registers by taking account of the physical symmetry of the Finite-Difference scheme reduces the amount of memory accesses. Through these optimizations, we achieve acceleration of 3.9 (8.1) on Xeon Phi (GPGPU) for the Semi-Lagrangian scheme and of 1.4 (3.9) on Xeon Phi (GPGPU) for the Finite-Different scheme with respect to the fully optimized codes on Sandy Bridge.
Autors: Yuuichi Asahi;Guillaume Latu;Takuya Ina;Yasuhiro Idomura;Virginie Grandgirard;Xavier Garbet;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jul 2017, volume: 28, issue:7, pages: 1974 - 1988
Publisher: IEEE
 
» Optimization of the Event-Driven Emergency Load-Shedding Considering Transient Security and Stability Constraints
Abstract:
Emergency control is an important measure for prevention of power system blackouts. This paper presents a new event-driven emergency load-shedding scheme that minimizes load shedding while meeting constraints on transient angle stability, voltage/frequency deviation security, and availability of load to be shed at any bus. The evaluation of these constraints is based on time domain trajectories provided by numerical simulations. The optimal event-driven load-shedding (OEDLS) model was created to minimize the total load-shedding cost. By analyzing the characteristics of the optimal solution of this model, a trajectory sensitivity based solution approach is presented. It linearizes the nonlinear OEDLS model through trajectory sensitivity and iteratively converges to the optimal solution. To accelerate the problem solving process, a parallel computation scheme is implemented for obtaining the trajectory sensitivities. The validity of the proposed algorithm and parallel computation scheme was tested and verified using two different power systems.
Autors: Xin Xu;Hengxu Zhang;Changgang Li;Yutian Liu;Wei Li;Vladimir Terzija;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 2581 - 2592
Publisher: IEEE
 
» Optimize the Signal Quality of the Composite Health  Index via Data Fusion for Degradation Modeling  and Prognostic Analysis
Abstract:
Due to the rapid development of sensing and computing technologies, multiple sensors have been widely used in a system to simultaneously monitor the health status of an operating unit. Such a data-rich environment creates an unprecedented opportunity to better understand the degradation behavior of the system and make accurate inferences about the remaining lifetime. Since data collected from multiple sensors are often correlated and each sensor data contains only partial information about the degraded unit, data fusion methodologies that integrate the data from multiple sensors provide an essential tool for degradation modeling and prognostics. To achieve this goal, a fundamental question needs to be answered first is how to measure the signal quality of a degradation signal. If such a question can be addressed, then the data fusion approach can be simplified as a mission-specific task: to construct a composite health index with the goal of optimizing its signal quality. In this paper, a new signal-to-noise ratio (SNR) metric that is tailored to the needs of degradation signals is proposed. Then, based on the new quality metric, we develop a data-level fusion model to construct a health index via fusion of multiple degradation-based sensor data. Our goal is that the developed health index provides a much better characterization of the health condition of the unit and thus leads to a better prediction of the remaining lifetime. A case study that involves the degradation dataset of aircraft gas turbine engines is conducted to numerically evaluate the performance of the developed health index regarding prognostics and further compare the result with existing literature.
Autors: Kaibo Liu;Abdallah Chehade;Changyue Song;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jul 2017, volume: 14, issue:3, pages: 1504 - 1514
Publisher: IEEE
 
» Optimized Adaptive Streaming of Multi-video Stream Bundles
Abstract:
In contrast to traditional video, multi-view video streaming allows viewers to interactively switch among multiple perspectives provided by different cameras. One approach to achieve such a service is to encode the video from all of the cameras into a single stream, but this has the disadvantage that only a portion of the received video data will be used, namely that required for the selected view at each point in time. In this paper, we introduce the concept of a “multi-video stream bundle” that consists of multiple parallel video streams that are synchronized in time, each providing the video from a different camera capturing the same event or movie. For delivery we leverage the adaptive features and time-based chunking of HTTP-based adaptive streaming, but now employing adaptation in both content and rate. Users are able to change their viewpoint on-demand and the client player adapts the rate at which data are retrieved from each stream based on the user's current view, the probabilities of switching to other views, and the user's current bandwidth conditions. A crucial component of such a system is the prefetching policy. For this we present an optimization model as well as a simpler heuristic that can balance the playback quality and the probability of playback interruptions. After analytically and numerically characterizing the optimal solution, we present a prototype implementation and sample results. Our prefetching and buffer management solution is shown to provide close to seamless playback switching when there is sufficient bandwidth to prefetch the parallel streams.
Autors: Niklas Carlsson;Derek Eager;Vengatanathan Krishnamoorthi;Tatiana Polishchuk;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jul 2017, volume: 19, issue:7, pages: 1637 - 1653
Publisher: IEEE
 
» Optimized Differential Self-Inductance Displacement Sensor for Magnetic Bearings: Design, Analysis and Experiment
Abstract:
The miniaturization requirements have been put forward to the sensors for the development of the modern industry. However, the traditional inductive displacement sensor applied to active magnetic bearings (AMBs) has complicated detection device and measuring circuit with excessive discrete components which cannot meet the requirements of the miniaturization. To remedy the infliction, an optimized differential self-inductance displacement sensor was designed for AMBs. Concretely, the operating principle of the self-inductance displacement sensor was analyzed in detail. Then the optimized structure was proposed and the measuring circuit was designed. After the designing, the performance of the sensor was analyzed. Based on the analysis and designing, a series of experiments were carried out to test the performance. The results demonstrated that the designed sensor can realize higher linearity, higher sensitivity, and wider dynamic response range than the traditional inductive displacement sensor. And it is suitable to the AMBs system, with higher rotation speed and small volume.
Autors: Kun Wang;Lisheng Zhang;Yun Le;Shiqiang Zheng;Bangcheng Han;Yinxiao Jiang;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4378 - 4387
Publisher: IEEE
 
» Optimized Periodic MoM for the Analysis and Design of Dual Polarization Multilayered Reflectarray Antennas Made of Dipoles
Abstract:
A hybrid version of the Method of Moments (MoM) is applied to the analysis of the scattering of plane waves by periodic multilayered structures containing dipoles at two metallization levels. The MoM matrix entries involving basis functions (BFs) at different metallization levels are computed in the spectral domain as double infinite summations with fast exponential convergence. The MoM matrix entries involving BFs at the same metallization level are computed in the spatial domain as double integrals, which require low-order quadrature rules. The integrands are cross correlations between BFs times multilayered periodic Green’s functions (MPGFs). The cross correlations between BFs are obtained in terms of elliptic integrals of first and second kind. Also, the MPGFs are accurately interpolated in 4-D in terms of both the spatial variables and the angles of incidence. The hybrid MoM proposed is used in the design of dual polarization reflectarray antennas under the local periodicity assumption. Thanks to the 4-D interpolation of the MPGFs, which minimizes the total number of MPGFs that have to be computed per reflectarray element, the proposed hybrid MoM is shown to be around 15 times faster than the standard spectral domain MoM in the design of the antennas.
Autors: Rafael Florencio;Rafael R. Boix;José A. Encinar;Giovanni Toso;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3623 - 3637
Publisher: IEEE
 
» Optimizing Channel-Statistics-Based Analog Beamforming for Millimeter-Wave Multi-User Massive MIMO Downlink
Abstract:
In this paper, we consider the design of analog beamformers for the downlink of multi-user massive multiple-input-multiple-output (MIMO) systems. We specifically investigate systems, where both link ends are equipped with hybrid digital/analog beamforming structures, where the analog beamformers are adapted based on second order channel statistics, reducing the training overhead as well as hardware effort. We present a framework for the optimization of such beamformers operating in mm-wave channels, exploiting the directional characteristics and sparse nature of such channels. We develop an approximate upper bound of the ergodic sum capacity, based on which efficient beamforming algorithms are devised. Simulation results show significant performance improvements of the proposed algorithms compared with the state-of-the-art algorithms.
Autors: Zheda Li;Shengqian Han;Andreas F. Molisch;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4288 - 4303
Publisher: IEEE
 
» Optimizing DF Cognitive Radio Networks With Full-Duplex-Enabled Energy Access Points
Abstract:
With the recent advances in radio frequency (RF) energy harvesting (EH) technologies, wireless powered cooperative cognitive radio network (CCRN) has drawn an upsurge of interest for improving the spectrum utilization with incentive to motivate joint information and energy cooperation between the primary and secondary systems. Dedicated energy beamforming is aimed at remedying the low efficiency of wireless power transfer, which nevertheless arouses out-of-band EH phases and thus low cooperation efficiency. To address this issue, in this paper, we consider a novel CCRN aided by full-duplex (FD)-enabled energy access points (EAPs) that can cooperate to wireless charge the secondary transmitter while concurrently receiving primary transmitter’s signal in the first transmission phase, and to perform decode-and-forward relaying in the second transmission phase. We investigate a weighted sum-rate maximization problem subject to transmitting power constraints as well as a total cost constraint using successive convex approximation techniques. A zero-forcing-based suboptimal scheme that requires only local channel state information for the EAPs to obtain their optimum receiving beamforming is also derived. Various tradeoffs between the weighted sum-rate and other system parameters are provided in numerical results to corroborate the effectiveness of the proposed solutions against the benchmark ones.
Autors: Hong Xing;Xin Kang;Kai-Kit Wong;Arumugam Nallanathan;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4683 - 4697
Publisher: IEEE
 
» Optimizing Subpixel Impervious Surface Area Mapping Through Adaptive Integration of Spectral, Phenological, and Spatial Features
Abstract:
Reliable subpixel impervious surface area (ISA) mapping at medium resolution is essential but difficult due to the complexity of land cover patterns within the urban/peri-urban area. In this letter, we proposed a framework to optimize subpixel ISA mapping performance with adaptive integration of features from spectral, phenological, and spatial dimensions. We utilized the recursive feature elimination to build the most discriminative feature pool. Then, the random forest (RF) model was adopted for the subpixel ISA mapping and the feature contribution quantification. We applied the proposed framework in two typical study sites and tested its utility by comparing it with three other subpixel mapping approaches. The experimental results suggested that the inclusion of complementary feature inputs beyond the spectral profile was beneficial in both study sites for identifying fractional imperviousness. In particular, the improvement was most pronounced for pixels suffering spectral variability or intra-annual land cover change. With the quantification of feature contribution to the RF model, we further illustrated the critical impact of environmental conditions on the feature adoption.
Autors: Chong Liu;Hui Luo;Yuan Yao;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jul 2017, volume: 14, issue:7, pages: 1017 - 1021
Publisher: IEEE
 
» Orientation Insensitive Antenna With Polarization Diversity for Wireless Capsule Endoscope System
Abstract:
An orientation insensitive antenna is proposed for the 2.4-GHz industrial, scientific, and medical band wireless capsule endoscopy system. To achieve the polarization diversity, three orthogonal currents are obtained by bending a dipole. Inversed T matching branch and meander lines are employed to gain better impendence matching and miniaturization. A normal dipole in capsule with single polarization is set as the reference antenna in simulation. The one-layer muscle phantom and the Gustav human body model are adopted in simulation. Minced pork is used during measurement. Communication links between the proposed capsule antenna and the external receiving antenna when they are in different orientations are measured to demonstrate the advantages the polarization diversity brings. According to the measured , the proposed antenna can transmit effectively even the orientation of the capsule is changed; therefore, direction insensitivity performance is achieved.
Autors: Yan Li;Yong-Xin Guo;Shaoqiu Xiao;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3738 - 3743
Publisher: IEEE
 
» Orientational Beamforming For UWB Signals
Abstract:
In this paper, we propose a new beamforming scheme for pulse-based signals, particularly, for ultra wideband pulses, by employing a random array geometry and an orientation matching of the arrays. Unlike conventional directional beamforming, the introduced scheme forms an array beam, being independent of a signal impinging direction for both near-fields and far-fields. As a consequence, it is advantageous to suppress unwanted interferences having same frequency contents and coexisting in the same arrival direction with reference to the desired signal. The proposed beamforming concept is analyzed together with the definitions of the −3dB beamwidth and restlobe level. Besides, the orientational beampatterns are compared with the directional beampatterns, and observed that the array responses are different according to the respective spatial processing domains.
Autors: Su Yee Aye;Boon Poh Ng;
Appeared in: IEEE Transactions on Communications
Publication date: Jul 2017, volume: 65, issue:7, pages: 3123 - 3132
Publisher: IEEE
 
» Outage Performance of Integrated Satellite-Terrestrial Networks With Hybrid CCI
Abstract:
We investigate the outage performance of an integrated satellite-terrestrial network undergoing hybrid co-channel interference (CCI), which comprises inter-component CCI from the satellite and intra-component CCI from adjacent base stations. Taking the interference power constraints imposed by satellite communications into account, we derive a closed-form expression for the outage probability (OP) of the terrestrial network, where the satellite link and terrestrial links are modeled as shadowed-Rician and Nakagami-m fading, respectively. Finally, simulation results demonstrate the validity of the theoretical analysis and show the effects of various key parameters on the OP performance.
Autors: Yuhan Ruan;Yongzhao Li;Cheng-Xiang Wang;Rui Zhang;Hailin Zhang;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1545 - 1548
Publisher: IEEE
 
» Output-Based Event-Triggered Control with Performance Guarantees
Abstract:
We propose an output-based event-triggered control solution for linear discrete-time systems with a performance guarantee relative to periodic time-triggered control, while reducing the communication load. The performance is expressed as an average quadratic cost and the plant is disturbed by Gaussian process and measurement noises. We establish several connections with previous works in the literature discussing, in particular, the relation to absolute and relative threshold policies. The usefulness of the results is illustrated through a numerical example.
Autors: Behnam Asadi Khashooei;Duarte J. Antunes;W. P. M. H. Heemels;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3646 - 3652
Publisher: IEEE
 
» Over-Molded Inductor (OMI)—Feasibility Demonstration in a DC–DC Converter
Abstract:
A significant fraction of the volume of a dc–dc power module is often occupied by the filter inductor and by the molding compound padding the unused space. This letter presents a method to fabricate an inductor in which the core is realized by molding a magnetic mixture over the circuit board. Permeability above 20 was achieved using a curing temperature not exceeding 250 °C, and no applied pressure. A power converter with input of 12 V, output of 1.2 V at 5 A, and switching frequency of 500 kHz was constructed to check the operation with a 1.1-μH over-molded inductor. The over-molded magnetic material did not adversely interfere with converter operation, e.g., switching noise was low. The maximum temperature of 48.3 °C and full-load efficiency of 82% are similar to those of the same circuit using a discrete inductor.
Autors: Ting Ge;Yi Yan;Guo-Quan Lu;Khai Ngo;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5738 - 5740
Publisher: IEEE
 
» Overview of Color Gamut Scalability
Abstract:
Displays’ new rendering capabilities combined with the ever-growing number of video applications have fueled the emergence of new video formats addressing wider color gamut and larger frame size. Thus, the need in scalable compression technology to provide backward compatibility with legacy devices and capitalize on the superior compression performance of High Efficiency Video Coding (HEVC) has increased significantly. This paper gives an overview of the work carried out in the Joint Collaborative Team on Video Coding of ITU-T Study Group 16 (VCEG) and ISO/IEC JTC1/SC29/WG11 motion picture experts group (MPEG) to define scalable extensions of HEVC (SHVC) targeting these market requirements. The color gamut scalability (CGS) tool of SHVC is specially designed to support efficient scalable coding with multiple layers in different color spaces. The genesis of the SHVC-CGS tool is presented and the performance of the various proposals is compared. Finally, the design of the recently adopted SHVC-CGS inter-layer prediction is detailed. The experimental results validate its efficiency in coding video with extended color gamut and high dynamic range.
Autors: Philippe Bordes;Pierre Andrivon;Xiang Li;Yan Ye;Yuwen He;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jul 2017, volume: 27, issue:7, pages: 1580 - 1594
Publisher: IEEE
 
» OxRAM RNG Circuits Exploiting Multiple Undesirable Nanoscale Phenomena
Abstract:
Compact, low-power random number generators (RNG) are essential for applications such as stochastic-, bioinspired-computing, data-encryption, cryptography in communication and security systems. We demonstrate two highly scalable hybrid CMOS-OxRAM RNG implementations based on single OxRAM and 2-OxRAM -circuits. We show how multiple undesirable nanoscale OxRAM phenomena, such as reset-current fluctuation, random telegraph noise (RTN), and reset-state resistance variability in HfO devices can be coupled to realize RNGs. We show that mitigation of history (memory) effect in 2-OxRAM RNGs can be achieved by using optional OxRAM switching and smaller sampling frequency. Using circuit simulations with calibrated compact models, the proposed hybrid RNG circuits have been validated for 10 nm thick HfO devices and 180 nm CMOS node. RNG performance is characterized using chi-square test, serial spectral test, and covariance/correlation-based analysis.
Autors: Shubham Sahay;Ashwani Kumar;Vivek Parmar;Manan Suri;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jul 2017, volume: 16, issue:4, pages: 560 - 566
Publisher: IEEE
 
» P(VDF-HFP) Polymer as Sensing Material for Capacitive Carbon Dioxide Sensors
Abstract:
P(VDF-HFP) polymer is investigated through both theoretical and experimental approaches as a sensing material for capacitive CO2 sensor applications. Analysis based on the Clausius–Mossotti model shows that larger CO2 solubility and larger dielectric constant contribute to high CO2 capacitive sensitivity, which shows that P(VDF-HFP) polymer has significantly higher CO2 sensitivity compared with Teflon when they have comparable CO2 solubility, which is supported by subsequent experimental demonstration. Cross-sensitivity to humidity and temperature are evaluated and discussed for both P(VDF-HFP) and Teflon polymers. Fourier Transform Infrared spectroscopy (FTIR) analysis further reveals that the electrostatic interaction of P(VDF-HFP) with CO2 is stronger than Teflon. The theoretical analyses and experimental demonstration indicate that P(VDF-HFP) is a promising sensing material to be applied for capacitive CO2 sensors operated at room temperature.
Autors: Lei Zhang;Mojtaba Rahimabady;Sze Yu Tan;Chin Yaw Tan;Shuting Chen;Yi Fan Chen;Kui Yao;Aurélie Humbert;Dimitri Soccol;Keyan Zang;Michael Bolt;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4349 - 4356
Publisher: IEEE
 
» Parallel Transportation Management and Control System for Subways
Abstract:
The subway’s daily management and control are too complicated to be handled by using traditional methods. Based on the artificial systems, computational experiments, and parallel execution (ACP) approach, the Parallel Transportation Management and Control System for Subways (PTMS -Subway) is proposed. First, the dynamic status perception and management platform for subways (SPMP-Subway) is constructed, and artificial subway systems (ASS) are designed and constructed, and then they are validated by the real-time data from SPMP-Subway. Then, the design content and construction process of computational experiments platform are performed. Finally, through the interactions of parallel execution system between actual subway and its ASS, a set of practical management and control algorithms can be validated and improved. PTMS-Subway can implement those advanced functions, such as real-time monitoring, warning, forecasting, scheduling optimization, incidence management, and so on, to improve its reliability, efficiency, safety, and service level. SPMP-Subway and PTMS-Subway have been piloted in Subway Lines 1 and 2 in Suzhou, China, and achieved the expected results and benefits successfully.
Autors: Gang Xiong;Dayong Shen;Xisong Dong;Bin Hu;Dong Fan;Fenghua Zhu;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Jul 2017, volume: 18, issue:7, pages: 1974 - 1979
Publisher: IEEE
 
» Parallelizing Exact and Approximate String Matching via Inclusive Scan on a GPU
Abstract:
In this study, to substantially improve the runtimes of exact and approximate string matching algorithms, we propose a tribrid parallel method for bit-parallel algorithms such as the Shift-Or and Wu-Manber algorithms. Our underlying idea is to interpret bit-parallel algorithms as inclusive-scan operations, which allow these bit-parallel algorithms to run efficiently on a graphics processing unit (GPU); we achieve this speed-up here because inclusive-scan operations not only eliminate duplicate searches between threads but also realize a GPU-friendly memory access pattern that maximizes memory read/write throughput. To realize our ideas, we first define two binary operators and then present a proof regarding the associativity of these operators, which is necessary for the parallelization of the inclusive-scan operations. Finally, we integrate the inclusive-scan scheme into a previous segmentation-based scheme to maximize search throughput, identifying the best tradeoff point between synchronization cost and duplicate work. Through our experiments, we compared our proposed method with previous segmentation-based methods and indexing-based sequence aligners. For online string matching, our proposed method performed 6.7-16.7 times faster than previous methods, achieving a search throughput of up to 1.88 terabits per second (Tbps) on a GeForce GTX TITAN X GPU. We therefore conclude that our proposed method is quite effective for decreasing the runtimes of online string matching of short patterns.
Autors: Yasuaki Mitani;Fumihiko Ino;Kenichi Hagihara;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jul 2017, volume: 28, issue:7, pages: 1989 - 2002
Publisher: IEEE
 
» Parameter Estimation of Three-Phase Transformer Models for Low-Frequency Transient Studies From Terminal Measurements
Abstract:
This paper introduces a three-phase reversible transformer model for the study of low-frequency transients. The model topology is obtained from the direct application of the principle of duality by drawing basic circuit elements on top of the transformer frame. The model parameters are obtained from terminal and physical size measurements as well as the characteristics of the iron core. The implementation of the model is based on standard drag-and-drop circuit elements available in electric circuit simulation programs. The model is validated with inrush current and normal open circuit laboratory measurements. The main advantage of this model is that the parameters remain the same for the simulation of different operating conditions from all terminals. This is true for transients involving deep saturation, normal loading operation, or open circuit.
Autors: Qiong Wu;Saeed Jazebi;Francisco de Leon;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jul 2017, volume: 53, issue:7, pages: 1 - 8
Publisher: IEEE
 

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