Electrical and Electronics Engineering publications abstract of: 11-2017 sorted by title, page: 14

» Multistage Security-Constrained HVAC/HVDC Transmission Expansion Planning With a Reduced Search Space
Abstract:
This paper proposes a new method to solve the multistage security-constrained transmission expansion planning problem, incorporating lines based on high-voltage alternating current (HVAC) and high-voltage direct current (HVDC) alternatives. A novel mixed-integer linear programming model, which incorporates transmission losses using a piecewise linearization, is presented. An efficient method to reduce the search space of the problem is developed to help in the solution process. Garver's 6-bus system and a modified Southern Brazilian system are used to show the precision and efficiency of the proposed approach. The tests are performed for cases with and without HVDC links and transmission losses. The results indicate that better expansion plans can be found by considering HVDC proposals in the expansion process. The promising trend of using HVDC lines in future networks to improve the reliability in the system is demonstrated.
Autors: Andres Hernando Dominguez;Leonardo H. Macedo;Antonio Hernando Escobar;Rubén Romero;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4805 - 4817
Publisher: IEEE
 
» Multiuser Millimeter Wave Beamforming Strategies With Quantized and Statistical CSIT
Abstract:
To alleviate the high cost of hardware in mm-wave systems, hybrid analog/digital precoding is typically employed. In the conventional two-stage feedback scheme, the analog beamformer is determined by beam search and feedback to maximize the desired signal power of each user. The digital precoder is designed based on quantization and feedback of effective channel to mitigate multiuser interference. Alternatively, we propose a one-stage feedback scheme, which effectively reduces the complexity of the signalling and feedback procedure. Specifically, the second-order channel statistics are leveraged to design digital precoder for interference mitigation while all feedback overhead is reserved for precise analog beamforming. Under a fixed total feedback constraint, we investigate the conditions under which the one-stage feedback scheme outperforms the conventional two-stage counterpart. Moreover, a rate splitting (RS) transmission strategy is introduced to further tackle the multiuser interference and enhance the rate performance. Consider: 1) RS precoded by the one-stage feedback scheme and 2) conventional transmission strategy precoded by the two-stage scheme with the same first-stage feedback as 1) and also certain amount of extra second-stage feedback. We show that 1) can achieve a sum rate comparable to that of 2). Hence, RS enables remarkable saving in the second-stage training and feedback overhead.
Autors: Mingbo Dai;Bruno Clerckx;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7025 - 7038
Publisher: IEEE
 
» Multivariate Detection of Power System Disturbances Based on Fourth Order Moment and Singular Value Decomposition
Abstract:
This paper presents a new method to detect power system disturbances in a multivariate context, which is based on Fourth Order Moment and multivariate analysis implemented as Singular Value Decomposition. The motivation for this development is that power systems are increasingly affected by various disturbances and there is a requirement for the analysis of measurements to detect these disturbances. The application results on the measurements of an actual power system in Europe illustrate that the proposed multivariate detection method achieves enhanced detection reliability and sensitivity.
Autors: Lianfang Cai;Nina F. Thornhill;Bikash C. Pal;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4289 - 4297
Publisher: IEEE
 
» Multiview Positron Attenuation Tomography
Abstract:
Positron attenuation tomography (PAT) is a new modality for imaging the linear attenuation coefficients (LACs) of magnetically constrained -ray beams in matter. A complete 3-D LAC image of an object can be made by measuring the positron annihilation rate density within it at a single orientation relative to the beam, and then applying the PAT transformation. The spatial resolution of this image is limited by the resolution of the positron emission tomography (PET), or other, system used to acquire the data as well as the scattering and gyration of the positrons around the magnetic field lines. The finite resolution of the PET system also leads to nonlinear artifacts associated with extended LAC discontinuities parallel to the beam. The mass thickness of an object that can be imaged is limited by the positron beam’s range in it. However, due to the directional nature of the imaging process as well as its discrete sampling, PAT images acquired at different view angles may each carry unique information on the object’s structure. This paper describes a forward model of PAT image formation and a backpropagation algorithm that, when used together to iteratively combine the data from multiple views, can improve the spatial resolution of PAT LAC images, extend their effective field of view, and reduce artifacts. The technique is demonstrated on measured and simulated data.
Autors: Charles C. Watson;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: Nov 2017, volume: 64, issue:11, pages: 2869 - 2877
Publisher: IEEE
 
» MVDC Three-Wire Supply Systems for Electric Railways: Design and Test of a Full SiC Multilevel Chopper
Abstract:
Currently, in electric railways, the old dc supply systems are reaching their limits. In several European railway networks, due to the line-voltage drops between substations, there are several sectors where traffic can no longer increase and where locomotives cannot operate at their nominal ratings. To improve the power capacity, a medium voltage dc (MVdc) three-wire supply system with voltage boosters based on imbricated cell multilevel choppers (ICMC) was proposed. In order to increase efficiency, the authors evaluate the potential of new SiC-mosfets in this topology. An opposition method test bench using two ICMCs was built with 1.7-kV/300-A half-bridge modules. The design of the multilevel converters takes into account the constraints related to high switching frequency operation (up to 50 kHz). Thanks to the opposition method, losses in ICMCs can be determined by electrical and thermal measurements with good accuracy. Finally, solutions with SiC-mosfets and Si-insulated gate bipolar transistors are compared in terms of efficiency.
Autors: Joseph Fabre;Philippe Ladoux;Eduard Solano;Guillaume Gateau;Jean-Marc Blaquière;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5820 - 5830
Publisher: IEEE
 
» Myocardium Segmentation From DE MRI Using Multicomponent Gaussian Mixture Model and Coupled Level Set
Abstract:
Objective: In this paper, we propose a fully automatic framework for myocardium segmentation of delayed-enhancement (DE) MRI images without relying on prior patient-specific information. Methods: We employ a multicomponent Gaussian mixture model to deal with the intensity heterogeneity of myocardium caused by the infarcts. To differentiate the myocardium from other tissues with similar intensities, while at the same time maintain spatial continuity, we introduce a coupled level set (CLS) to regularize the posterior probability. The CLS, as a spatial regularization, can be adapted to the image characteristics dynamically. We also introduce an image intensity gradient based term into the CLS, adding an extra force to the posterior probability based framework, to improve the accuracy of myocardium boundary delineation. The prebuilt atlases are propagated to the target image to initialize the framework. Results: The proposed method was tested on datasets of 22 clinical cases, and achieved Dice similarity coefficients of 87.43 ± 5.62% (endocardium), 90.53 ± 3.20% (epicardium) and 73.58 ± 5.58% (myocardium), which have outperformed three variants of the classic segmentation methods. Conclusion: The results can provide a benchmark for the myocardial segmentation in the literature. Significance: DE MRI provides an important tool to assess the viability of myocardium. The accurate segmentation of myocardium, which is a prerequisite for further quantitative analysis of myocardial infarction (MI) region, can provide important support for the diagnosis and treatment management for MI patients.
Autors: Jie Liu;Xiahai Zhuang;Lianming Wu;Dongaolei An;Jianrong Xu;Terry Peters;Lixu Gu;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Nov 2017, volume: 64, issue:11, pages: 2650 - 2661
Publisher: IEEE
 
» Nanodevice Arrays for Peripheral Nerve Fascicle Activation Using Ultrasound Energy-Harvesting
Abstract:
We propose the use of wireless, energy harvesting, implanted nanodevice arrays with electrodes for selective stimulation of peripheral nerves in the human body. We calculate the input ultrasound energy and harvested power for single fixed-size nanowire-based nanodevices at different tissue depths and compare these with the current and voltage levels required for peripheral neural stimulation. We model the dimensioning of arrays of nanodevices, embedded in biocompatible tissue patches, to meet these neural stimulation requirements. Selectivity of activation of particular nerve bundles requires that the output voltage and current of the array can be varied to increase or decrease penetration into the neural tissue. This variation can be achieved by changing the energized area of the array and/or by decreasing the incident ultrasound power. However, the array must be implanted horizontally relative to the incident ultrasound as any tilting of the nanodevices will reduce the harvested energy. The proposed approach provides a longer-term implant solution for nerve stimulation that allows the patient greater freedom of movement than with embedded tethered electrodes.
Autors: Michael Donohoe;Brendan Jennings;Josep Miquel Jornet;Sasitharan Balasubramaniam;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 919 - 930
Publisher: IEEE
 
» Nanoislands-Based Charge Trapping Memory: A Scalability Study
Abstract:
Zinc-oxide (ZnO) and zirconia (ZrO2) metal oxides have been studied extensively in the past few decades with several potential applications including memory devices. In this work, a scalability study, based on the ITRS roadmap, is conducted on memory devices with ZnO and ZrO2 nanoislands charge trapping layer. Both nanoislands are deposited using atomic layer deposition; however, the different sizes, distribution, and properties of the materials result in different memory performance. The results show that at the 32-nm node charge trapping memory with 127 ZrO2 nanoislands can provide a 9.4 V memory window. However, with ZnO only, 31 nanoislands can provide a window of 2.5 V. The results indicate that ZrO2 nanoislands are more promising than ZnO in scaled down devices due to their higher density, higher-k, and the absence of quantum confinement effects.
Autors: Nazek El-Atab;Irfan Saadat;Krishna Saraswat;Ammar Nayfeh;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 1143 - 1146
Publisher: IEEE
 
» Nanopatterned Optical Fiber Tip for Guided Mode Resonance and Application to Gas Sensing
Abstract:
This paper reports on an efficient and convenient method of patterning nanostructures on the cleaved facet of an optical fiber to realize a high-performance fiber-optic gas sensor. The fabrication method utilizes an ultraviolet assisted nanoimprint lithography to transfer nanoscale patterns from a pre-formed stamp to the fiber tip. The novelty of this paper lies in utilizing simpler fabrication steps with better control over angle of contact at the fiber tip, which leads to rapid and precise formation of nanostructures with well-defined features. A periodic array of polymer nanoposts are formed at the fiber tip and coated with titanium dioxide to serve as a guided mode resonant (GMR) device. A gas sensor is realized by coating the GMR structure with a thin layer of graphene oxide (GO) nanosheets. We have utilized the resonance sensitivity of the nanopatterned fiber-tip gas sensor to surrounding refractive index. The abundant functional groups available at GO provides an effective adsorption surface for gas molecules. Microscopic imaging and spectroscopic studies are conducted to illustrate the structural and optical properties, and gas-sensing performance of the sensor. Volatile organic compounds, such as ethylene and methanol, associated with crop plant health, are detected by the sensor. The sensor provides sensitivities of 0.92 and 1.37 pm/ppm for ethylene and methanol vapors, respectively, with a three-fold enhancement in sensitivity and 50% reduction in response time compared with the non-GO coated counterpart. In addition, the sensor demonstrates good stability and reproducibility, thus having a great potential in fiber-optic remote sensing applications.
Autors: Shawana Tabassum;Ratnesh Kumar;Liang Dong;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7262 - 7272
Publisher: IEEE
 
» Nanostructured La–Sr–Mn–Co–O Films for Room-Temperature Pulsed Magnetic Field Sensors
Abstract:
The results of Co substitution for Mn in nanostructured La1-xSrxMn1-yCoyO3 films () grown on polycrystalline Al2O3 substrates by pulsed-injection metal-organic chemical vapor deposition technique, are presented. The Co content y in the films was changed as follows: 0; 0.023; 0.053; 0.078. The resistivity ( dependences on temperature in zero magnetic field was investigated in the temperature range 5–300 K. It was found that the increase in Co content up to 0.078 results in the decrease of metal-insulator transition temperature and increase of the resistivity. The results of nanostructured films are compared with the epitaxial films grown on LaAlO3 substrate keeping the same technological conditions. The magnetoresistance (MR) and MR anisotropy (MRA) were investigated at room temperature (290 K) in permanent magnetic fields up to 2.35 T, and pulsed magnetic fields up to 20 T. It was found that the highest MR values are obtained for the intermediate Co content: , while the MRA decreased with the increase of Co content. The results are discussed within the double-exchange interaction model for the perovskite oxides. The possibility to apply the manganite-cobaltite films for the development of room temperature B-scalar magnetic field sensors is considered.
Autors: Nerija Zurauskiene;Vakaris Rudokas;Saulius Balevicius;Skirmantas Kersulis;Voitech Stankevic;Remigijus Vasiliauskas;Valentina Plausinaitiene;Milita Vagner;Rasuole Lukose;Martynas Skapas;Remigijus Juskenas;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Narrow-Band Interference Suppression via RPCA-Based Signal Separation in Time–Frequency Domain
Abstract:
Narrow-band interference (NBI) is a critical issue for synthetic aperture radar (SAR), in which the imaging quality can be degraded severely. To suppress NBI effectively, a novel interference suppression algorithm using robust principal component analysis (RPCA) based signal separation in time–frequency domain is proposed. The RPCA algorithm is introduced for signal separation in the time–frequency domain for the first time. The fundamental assumption of RPCA is that a matrix can be modeled as a combination of a low-rank matrix and a sparse counterpart. In terms of the SAR echo, the short time Fourier transformation (STFT) matrix of mixed signals (i.e., useful SAR signals and NBIs) well fits the assumption of RPCA. Based on this property, radar echoes are first transformed into the time–frequency domain by STFT to form an STFT matrix. Then, the RPCA algorithm is used to decompose the STFT matrix into a low-rank matrix (i.e., NBIs) and a sparse matrix (i.e., useful signals). Finally, the NBIs can be reconstructed and subtracted from the echoes to realize the interference suppression. The experimental results of simulated and measured data demonstrate that the proposed algorithm not only can suppress interference effectively, but also preserve the useful information as much as possible.
Autors: Jia Su;Haihong Tao;Mingliang Tao;Ling Wang;Jian Xie;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 5016 - 5025
Publisher: IEEE
 
» Narrow-Sense BCH Codes Over $ {mathrm {GF}}(q)$ With Length $n=frac {q^{m}-1}{q-1}$
Abstract:
Cyclic codes are widely employed in communication systems, storage devices, and consumer electronics, as they have efficient encoding and decoding algorithms. BCH codes, as a special subclass of cyclic codes, are in most cases among the best cyclic codes. A subclass of good BCH codes are the narrow-sense BCH codes over with length . Little is known about this class of BCH codes when . The objective of this paper is to study some of the codes within this class. In particular, the dimension, the minimum distance, and the weight distribution of some ternary BCH codes with length are determined in this paper. A class of ternary BCH codes meeting the Griesmer bound is identified. An application of some of the BCH codes in secret sharing is also investigated.
Autors: Shuxing Li;Cunsheng Ding;Maosheng Xiong;Gennian Ge;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7219 - 7236
Publisher: IEEE
 
» Narrowband IoT Data Transmission Procedures for Massive Machine-Type Communications
Abstract:
Large-scale deployments of massive machinetype communications involve several challenges on cellular networks. To address the challenges of massive machine-type communications, or more generally, the Internet of Things (IoT), the 3GPP has developed Narrowband IoT (NB-IoT) as part of Release 13. NB-IoT is designed to provide better indoor coverage, support of a massive number of low-throughput devices, with relaxed delay requirements, and lower energy consumption. NB-IoT reuses Long Term Evolution functionality with simplifications and optimizations. Particularly for small data transmissions, NB-IoT specifies two procedures to reduce the required signaling: one of them based on the control plane and the other on the user plane (UP). In this work, we provide an overview of these procedures as well as an evaluation of their performance. The results of the energy consumption show both optimizations achieve a battery lifetime extension of more than two years for a large range in the considered cases, and up to eight years for CP with good coverage. In terms of cell capacity relative to Service Request, CP achieves gains from 26 to 224 percent, and UP ranges from 36 to 165 percent. The comparison of CP and UP optimizations yields similar results, except for some specific configurations.
Autors: Pilar Andres-Maldonado;Pablo Ameigeiras;Jonathan Prados-Garzon;Jorge Navarro-Ortiz;Juan M. Lopez-Soler;
Appeared in: IEEE Network
Publication date: Nov 2017, volume: 31, issue:6, pages: 8 - 15
Publisher: IEEE
 
» Natural Language Requirements Processing: A 4D Vision
Abstract:
Natural language processing (NLP) and requirements engineering (RE) have had a long relationship, yet their combined use isn’t well established in industrial practice. This situation should soon change. The future evolution of the application of NLP technologies in RE can be viewed from four dimensions: discipline, dynamism, domain knowledge, and datasets.
Autors: Alessio Ferrari;Felice Dell’Orletta;Andrea Esuli;Vincenzo Gervasi;Stefania Gnesi;
Appeared in: IEEE Software
Publication date: Nov 2017, volume: 34, issue:6, pages: 28 - 35
Publisher: IEEE
 
» Near-Optimal SOC Trajectory for Traffic-Based Adaptive PHEV Control Strategy
Abstract:
The optimal charge and discharge management of the energy storage system (ESS) has a pivotal role in development of the energy management system for the plug-in hybrid electric vehicles (PHEV). This research aims to estimate a near optimal trajectory of ESS state of charge (SOC) to be employed in traffic-based adaptive PHEV control strategy to enhance fuel economy in various driving cycles. In the first step, several driving cycles are developed based on the real-world driving data. Experimental map-based Pontryagin's minimum principle control strategy is designed to extract the optimal SOC trajectories for different cycles. The achieved optimal data is then used to create the database employed for training a Nero-Fuzzy system. The SOC trajectories, estimated under the light of the obtained fuzzy inference system, are employed as the reference SOC profiles in adaptive equivalent consumption minimization strategy. The simulation results reveal that the proposed approach provides near optimal SOC trajectory and improves the equivalent fuel economy in various driving cycles. Moreover, this adaptive near optimal control strategy could be applied on-line as it doesn't require the knowledge of the entire driving cycle, and only the trip length and the average speed should be known a priori.
Autors: Morteza Montazeri-Gh;Zeinab Pourbafarani;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9753 - 9760
Publisher: IEEE
 
» Nebula: Distributed Edge Cloud for Data Intensive Computing
Abstract:
Centralized cloud infrastructures have become the popular platforms for data-intensive computing today. However, they suffer from inefficient data mobility due to the centralization of cloud resources, and hence, are highly unsuited for geo-distributed data-intensive applications where the data may be spread at multiple geographical locations. In this paper, we present Nebula: a dispersed edge cloud infrastructure that explores the use of voluntary resources for both computation and data storage. We describe the lightweight Nebula architecture that enables distributed data-intensive computing through a number of optimization techniques including location-aware data and computation placement, replication, and recovery. We evaluate Nebula performance on an emulated volunteer platform that spans over 50 PlanetLab nodes distributed across Europe, and show how a common data-intensive computing framework, MapReduce, can be easily deployed and run on Nebula. We show Nebula MapReduce is robust to a wide array of failures and substantially outperforms other wide-area versions based on emulated existing systems.
Autors: Albert Jonathan;Mathew Ryden;Kwangsung Oh;Abhishek Chandra;Jon Weissman;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Nov 2017, volume: 28, issue:11, pages: 3229 - 3242
Publisher: IEEE
 
» Need to build a better hospital? Use chip design [Spectral Lines]
Abstract:
Deepak Aatresh, an electrical and computer engineer from India, joined Intel in 1989 as a chip designer—after reading an article I wrote for IEEE Spectrum on Intel’s project to build the first million-transistor chip! After seven years at Intel, he moved on to communications hardware companies. Then, in 2008, bitten by the startup bug but without a particular startup idea in mind, he joined Artiman Ventures as an entrepreneur-in-residence. He thought he'd try to find ways to reduce energy waste and improve energy efficiency.
Autors: Tekla S. Perry;
Appeared in: IEEE Spectrum
Publication date: Nov 2017, volume: 54, issue:11, pages: 6 - 6
Publisher: IEEE
 
» Net Shape Processing of Alnico Magnets by Additive Manufacturing
Abstract:
Alternatives to rare earth permanent magnets, such as alnico, will reduce supply instability, increase sustainability, and could decrease the cost of permanent magnets, especially for high-temperature applications, such as traction drive motors. Alnico magnets with moderate coercivity, high remanence, and relatively high-energy product are conventionally processed by directional solidification and (significant) final machining, contributing to increased costs and additional material waste. Additive manufacturing (AM) is developing as a cost effective method to build net-shape 3-D parts with minimal final machining and properties comparable to wrought parts. This paper describes initial studies of net-shape fabrication of alnico magnets by AM using a laser engineered net shaping (LENS) system. High-pressure gas atomized pre-alloyed powders of two different modified alnico “8” compositions, with high purity and sphericity, were built into cylinders using the LENS process, and followed by heat treatment. The magnetic properties showed improvement over their cast and sintered counterparts. The resulting alnico permanent magnets were characterized using scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and hysteresisgraph measurements. These results display the potential for net-shape processing of alnico permanent magnets for use in next generation traction-drive motors and other applications requiring high temperatures and/or complex engineered part geometries.
Autors: Emma Marie Hamilton White;Aaron Gregory Kassen;Emrah Simsek;Wei Tang;Ryan Timothy Ott;Iver Eric Anderson;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» Network Navigation With Scheduling: Error Evolution
Abstract:
Network navigation is a promising paradigm for providing location awareness in wireless environments, where nodes estimate their locations based on sensor measurements and prior knowledge. In the presence of limited wireless resources, only a subset rather than all of the node pairs can perform inter-node measurements. The procedure of selecting node pairs at different times for inter-node measurements, referred to as network scheduling, affects the evolution of the localization errors. Thus, it is crucial to design efficient scheduling strategies for network navigation. This paper introduces situation-aware scheduling that exploits network states to select measurement pairs, and develops a framework to characterize the effects of scheduling strategies and of network settings on the error evolution. In particular, both sufficient and necessary conditions for the boundedness of the error evolution are provided. Furthermore, opportunistic and random situation-aware scheduling strategies are proposed, and bounds on the corresponding time-averaged network localization errors are derived. These strategies are shown to be optimal in terms of the error scaling with the number of agents. Finally, the reduction of the error scaling by increasing the number of simultaneous measurement pairs is quantified.
Autors: Tianheng Wang;Yuan Shen;Andrea Conti;Moe Z. Win;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7509 - 7534
Publisher: IEEE
 
» Network Service Chaining in Fog and Cloud Computing for the 5G Environment: Data Management and Security Challenges
Abstract:
In the last few years, we have seen an exponential increase in the number of Internet-enabled devices, which has resulted in popularity of fog and cloud computing among end users. End users expect high data rates coupled with secure data access for various applications executed either at the edge (fog computing) or in the core network (cloud computing). However, the bidirectional data flow between the end users and the devices located at either the edge or core may cause congestion at the cloud data centers, which are used mainly for data storage and data analytics. The high mobility of devices (e.g., vehicles) may also pose additional challenges with respect to data availability and processing at the core data centers. Hence, there is a need to have most of the resources available at the edge of the network to ensure the smooth execution of end-user applications. Considering the challenges of future user demands, we present an architecture that integrates cloud and fog computing in the 5G environment that works in collaboration with the advanced technologies such as SDN and NFV with the NSC model. The NSC service model helps to automate the virtual resources by chaining in a series for fast computing in both computing technologies. The proposed architecture also supports data analytics and management with respect to device mobility. Moreover, we also compare the core and edge computing with respect to the type of hypervisors, virtualization, security, and node heterogeneity. By focusing on nodes' heterogeneity at the edge or core in the 5G environment, we also present security challenges and possible types of attacks on the data shared between different devices in the 5G environment.
Autors: Rajat Chaudhary;Neeraj Kumar;Sherali Zeadally;
Appeared in: IEEE Communications Magazine
Publication date: Nov 2017, volume: 55, issue:11, pages: 114 - 122
Publisher: IEEE
 
» Network Services Chaining in the 5G Vision
Abstract:
Autors: Jordi Mongay Batalla;George Mastorakis;Constandinos X. Mavromoustakis;Ciprian Dobre;Naveen Chilamkurti;Stefan Schaeckeler;
Appeared in: IEEE Communications Magazine
Publication date: Nov 2017, volume: 55, issue:11, pages: 112 - 113
Publisher: IEEE
 
» Network-Coded Multiple Access with High-Order Modulations
Abstract:
This paper presents the first network-coded multiple access (NCMA) system prototype operated on high-order modulations up to 16-QAM. NCMA jointly exploits physical-layer network coding (PNC) and multiuser decoding (MUD) to boost throughput of multipacket reception systems. Direct generalization of the existing NCMA decoding algorithm, originally designed for BPSK, to high-order modulations, will lead to huge performance degradation. The throughput degradation is caused by the relative phase offset between received signals from different nodes. To circumvent the phase offset problem, this paper investigates an NCMA system with multiple receive antennas at the access point, referred to as MIMO-NCMA. We put forth a low-complexity symbol-level NCMA decoder that, together with MIMO, can substantially alleviate the performance degradation induced by relative phase offset. To demonstrate the feasibility and advantage of MIMO-NCMA for high-order modulations, we implemented our designs on software-defined radio. Our experimental results show that the throughput of QPSK MIMO-NCMA is double that of both BPSK NCMA and QPSK MUD at SNR = 10 dB. For higher signal-to-noise ratios at which 16-QAM can be supported, the throughput of MIMO-NCMA can be as high as 3.5 times that of BPSK NCMA. Overall, this paper provides an implementable framework for high-order modulated NCMA.
Autors: Haoyuan Pan;Lu Lu;Soung Chang Liew;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9776 - 9792
Publisher: IEEE
 
» Network-Constrained Multiperiod Auction for Pool-Based Electricity Markets of Hydrothermal Systems
Abstract:
Network-constrained market clearing procedures in pool-based electricity markets of hydropower systems have traditionally neglected the constraints associated with physical and operating aspects of hydroelectric generation (hydraulic constraints). Such constraints are generally taken into account by means of expost procedures, which may lead to suboptimal results regarding social welfare function. This paper proposes a network-constrained auction model for hydrothermal systems that represents the hydraulic constraints in detail. The objectives of the paper are twofold: the analysis of the impact of hydraulic constraints on market clearing prices and on generation/consumption scheduling and the analysis of the influence of strategic offering of hydro plants in the operation of a hydraulic cascade. As some of the hydraulic constraints are nonlinear and intertemporal, linearization techniques are applied, resulting in a mixed-integer linear programming problem.
Autors: Augusto Cesar Pereira;Alberto Quialheiro de Oliveira;Edméa Cássia Baptista;Antonio Roberto Balbo;Edilaine Martins Soler;Leonardo Nepomuceno;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4501 - 4514
Publisher: IEEE
 
» Neurogenesis Enhances Response Specificity to Spatial Pattern Stimulation in Hippocampal Cultures
Abstract:
Objective: Adult neurogenesis in the hippocampus facilitates cognitive functions such as pattern separation in mammals. However, it remains unclear how newborn neurons mediate changes in neural networks to enhance the pattern separation ability. Here, we developed an in vitro model of adult neurogenesis using rat hippocampal cultures in order to investigate whether newborn neurons can be directly incorporated into neural networks related to pattern separation to produce functional improvements. Method: We optimized at schedule of basic fibroblast growth factor (bFGF) administration to enhance neurogenesis, and then used a microelectrode array system to evaluate the responses of neural cultures to two different spatial pattern stimuli (L and inverted L shapes) before and after training. Results: We found that early synaptic response times to a given pattern were shortened after training, and that this effect was more pronounced in cultures treated with bFGF. Furthermore, bFGF-treated cultures showed improved response specificity after training as indicated by calculated Kullback–Leibler divergence values, suggesting that pattern separation was better achieved in cultures with enhanced neurogenesis. Conclusion: Neural networks containing greater numbers of immature neurons exhibited higher response specificity to spatial pattern stimulation, suggesting the improvement of the pattern separation by neurogenesis enhancement. Significance: These results are the first in vitro demonstration that neurogenesis improves pattern separation. Our novel in vitro system will be a useful tool for investigating the contribution of adult neurogenesis to cognitive functions.
Autors: Yukimi Tanaka;Takuya Isomura;Kenta Shimba;Kiyoshi Kotani;Yasuhiko Jimbo;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Nov 2017, volume: 64, issue:11, pages: 2555 - 2561
Publisher: IEEE
 
» Neuromorphic Architecture With 1M Memristive Synapses for Detection of Weakly Correlated Inputs
Abstract:
Neuromorphic computing takes inspiration from the brain to build highly parallel, energy- and area-efficient architectures. Recently, hardware realizations of neurons and synapses using memristive devices were proposed and applied for the task of correlation detection. However, for weakly correlated signals, this task becomes challenging because of the variability and the asymmetric conductance response of the memristive devices. In this brief, we propose a high-density memristive system realized using nanodevices based on phase-change technology. We present a noise-robust phase-change implementation of a neuron and a synaptic learning rule that is capable of capturing patterns of weakly correlated inputs. We experimentally demonstrate the operation with a correlation coefficient as low as 0.2 using a record number of 1M phase-change synapses.
Autors: Stanisław Woźniak;Angeliki Pantazi;Severin Sidler;Nikolaos Papandreou;Yusuf Leblebici;Evangelos Eleftheriou;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Nov 2017, volume: 64, issue:11, pages: 1342 - 1346
Publisher: IEEE
 
» New Algorithms for Verification of Relative Observability and Computation of Supremal Relatively Observable Sublanguage
Abstract:
In this technical note, we present a new property of relative observability, and based on this property, we propose two algorithms: the first one, that has polynomial complexity, verifies if a regular language is relatively observable; the second algorithm computes the supremal relatively observable sublanguage of a given regular language. Although the latter has exponential complexity, it is more efficient than a recently proposed algorithm, which has double exponential complexity. Moreover, the algorithm proposed here has polynomial complexity when the automaton that marks the specification language is state partition.
Autors: Marcos V. S. Alves;Lilian K. Carvalho;João C. Basilio;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5902 - 5908
Publisher: IEEE
 
» New Approach to Increase CNT Contents in Electrodeposited Ni-CNT Composite Thin Films by Modified Current Conditions
Abstract:
In this paper, an electrodeposition method for nickel (Ni)-multiwalled carbon nanotubes (MWCNTs) composite thin films is presented. The composite film is deposited using an electrolyte in which MWCNTs are randomly dispersed. Two kinds of MWCNTs annealed at 1200 °C and 2600 °C were used for the electrodeposition using pulse or sine waveforms. An electrodeposition condition using CNT annealed at 1200 °C and sine waveform with maximum current 0.2 A and frequency 5.0 Hz results in a maximum CNT weight fraction of 5.4% in the composite film. The electrodeposited film with the maximum CNT content shows a microindentation hardness of 17.0 GPa, which is approximately 1.45 times greater than that of a pure Ni film. Moreover, mechanical strengthening is found in the composite films due to the addition of CNTs. This result shows that the electrodeposition for the Ni-MWCNT composite thin film with modified current condition would be applicable to microsystem, which requires micromechanical components with high mechanical strength.
Autors: Akhtar Muhammad Shahrukh;Zhonglie An;Masaya Toda;Takahito Ono;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 931 - 938
Publisher: IEEE
 
» New Bounds for Frameproof Codes
Abstract:
Frameproof codes are used to fingerprint digital data. They can prevent copyrighted materials from unauthorized use. In this paper, we study upper and lower bounds for -frameproof codes of length over an alphabet of size . The upper bound is based on a combinatorial approach and the lower bound is based on a probabilistic construction. Both bounds can improve one of the previous results when is small compared with , say for some constant . Furthermore, we pay special attention to binary frameproof codes. We show a binary -frameproof code of length cannot have more than codewords if .
Autors: Chong Shangguan;Xin Wang;Gennian Ge;Ying Miao;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7247 - 7252
Publisher: IEEE
 
» New Formulation and Strong MISOCP Relaxations for AC Optimal Transmission Switching Problem
Abstract:
As the modern transmission control and relay technologies evolve, transmission line switching has become an important option in power system operators’ toolkits to reduce operational cost and improve system reliability. Most recent research has relied on the DC approximation of the power flow model in the optimal transmission switching problem. However, it is known that DC approximation may lead to inaccurate flow solutions and also overlook stability issues. In this paper, we focus on the optimal transmission switching problem with the full AC power flow model, abbreviated as AC optimal transmission switching (AC OTS). We propose a new exact formulation for AC OTS and its mixed-integer second-order cone programming relaxation. We improve this relaxation via several types of strong valid inequalities inspired by the recent development for the closely related AC optimal power flow problem [Kocuk et al., “Strong SOCP relaxations for the optimal power flow problem,” Oper. Res., vol. 64, no. 6, pp. 1177–1196, 2016]. We also propose a practical algorithm to obtain high-quality feasible solutions for the AC OTS problem. Extensive computational experiments show that the proposed formulation and algorithms efficiently solve IEEE standard and congested instances and lead to significant cost benefits with provably tight bounds.
Autors: Burak Kocuk;Santanu S. Dey;Xu Andy Sun;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4161 - 4170
Publisher: IEEE
 
» New Method of Screening Out Outlier; Expanded Part Average Testing During Package Level Test
Abstract:
To achieve the automotive quality for semiconductor devices represented by “zero-defect,” part average testing (PAT) is actively applied to outgoing test. PAT has been generally used on wafer level test. This time we expanded it to package level test and established the method of detecting the characteristic variations and screening out the outliers. Moreover, we suggest a way of thinking about the outliers and consideration on the basis of the actual data analysis. We were especially conscious of the statistical meaning of the outliers which were detected. It has been demonstrated that the expanded PAT to package level test can reject the outliers of characteristics variation even within spec. The outliers in distribution of characteristic variations were detected by maintaining chip traceability. The new method can screen out outliers outside the 6-sigma within spec, and there was a clear inflection point between the distribution of the abnormal data and that of the population. It was assumed that hidden failure devices which had not been rejected as early failure were screened out. Detecting the outlier with the new method can reduce the failure rate to the target.
Autors: Tadashi Sakamoto;Kazunori Yofu;Takashi Kyuho;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 351 - 356
Publisher: IEEE
 
» New Multiferroic Composite Materials Consisting of Ferromagnetic, Ferroelectric, and Polymer Components
Abstract:
The multiferroic ferroelectric–ferromagnetic-polymer composite systems, consisting of ferroelectric PZT particles, ferromagnetic NdFeB (or barium ferrite) particles, and silicone matrix, were investigated. The influence of the polymer Young’s modulus on the properties was determined. The coercivity of elastomers with the same magnetic fillers in different matrices differs by a factor of 7. The influence of magnetic field on electric properties was investigated. Magnetodielectric effect in three-phase samples was found to be non-monotonic. The influence of electric field on magnetic properties of elastomers was investigated. The magnetoelectric effect under an applied electric field in new three-phase material was discovered.
Autors: Liudmila A. Makarova;Valeria V. Rodionova;Yuliya A. Alekhina;Tatiana S. Rusakova;Aleksander S. Omelyanchik;Nikolai S. Perov;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 7
Publisher: IEEE
 
» New Single-Phase Flux Switching Axial Flux Permanent Magnet Motor
Abstract:
In this paper, a new topology of a single-phase flux switching permanent magnet motor (FSPM) is presented. Unlike conventional FSPMs, the air-gap flux flows in the axial direction, and therefore, it is named the flux switching axial flux permanent magnet motor (FS AFPM). The proposed single-phase FS AFPM has a compact disc-type structure, four stator pole teeth, and two rotor pole teeth (4/2 combination). However, a number of the stator poles as well as the rotor poles can be easily increased, due to an enlarged circumferential length. It has two discs, one for the stator and other for the rotor. Like conventional FSPMs, this machine has a simple salient rotor pole structure. Along with the armature windings, the PMs are also embedded in the stator. A 3-D finite-element analysis is carried out for the characteristic analysis of the proposed single-phase FS AFPM. For the enhancement of the self-starting torque capability and unidirectional rotation, the rotor pole is tapered.
Autors: Qurban Ali Shah Syed;Haris Kurtović;Ingo Hahn;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» New Skills Needed: Structural Transformation in the Electricity Industry [In My View]
Abstract:
Presents an interview conducted with Fatih Guvenen, a University of Minnesota economist, about a new analysis of the lifetime earnings of American workers. The study was done for the National Bureau of Economic Research and clearly shows that the market for workers has irreversibly changed in major ways. Discusses how such structural transformation will impact the electricity industry.
Autors: Mark Ahlstrom;
Appeared in: IEEE Power and Energy Magazine
Publication date: Nov 2017, volume: 15, issue:6, pages: 116 - 112
Publisher: IEEE
 
» NiCuZn Ferrite Cores by Gelcasting: Processing and Properties
Abstract:
We used gelcasting, a pressure-less processing technology for fabricating ceramic parts, to make NiCuZn ferrite cores, which are traditionally made by a process that requires high hydrostatic pressure. A commercial NiCuZn ferrite powder was mixed with water, dispersant, and organic monomers to form a slurry, and then cast it into a mold of toroid shape followed by sintering at 900 °C, 950 °C, and 1000 °C for two hours. The sintered core mass density was found to increase with sintering temperature. The magnetic properties of the cores, i.e., complex permeability and core-loss density, were measured. We found that the real part of the permeability increased with sintering temperature from about 44 at 900 °C to 78 at 1000 °C. The core-loss density data at 5 MHz showed that the cores sintered at 950 °C had the lowest core-loss density; approximately 50% lower than that of a commercial NiZn ferrite (4F1) core. Since gelcasting does not require pressure and is scalable and low cost, it has the potential to make magnetic cores with intricate shapes and sizes for desired coupling of magnetic fluxes to improve efficiency and power-density of power electronics converters.
Autors: Lanbing Liu;Yi Yan;Khai D. T. Ngo;Guo-Quan Lu;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5728 - 5733
Publisher: IEEE
 
» NO Abatement Using Microwave Micro Plasma Generated With Granular Activated Carbon
Abstract:
Abatement of NO using microwave micro-plasma is presented in this paper. The micro-plasma is generated using granular activated carbon (GAC) particles of size (2–3 mm) in loosely fluidized bed in a microwave cavity operated at 2.45 GHz. A single-mode microwave cavity reactor (SMMCR) was constructed and microwave was injected through another slotted single-mode waveguide in a sandwiched manner. COMSOL Multiphysics software was used to investigate the microwave electric field and the power density within the SMMCR. Gas mixture of air and 500 ppm NO (in N2) at the flow rate of 2 l/min was passed through a quartz tube centered within the SMMCR, while the supplied microwave power was very low 10–80 W and corresponding NO reduction was greater than 98%. The mass of GAC used for generating the plasma was 5g. The efficiency of NO reduction is found to be 24.84 g(NO)/kWh. When air is mixed with NO (in N ), the efficiency of NOx reduction achieved vary greatly with respect to the supplied microwave energy, and behavior has become complex and is not predictable, which needs further investigation. A gas analyzer (testo 350) was used to measure the gas (NO, NO , CO, and O) concentration and temperature.
Autors: Nadarajah Manivannan;Givanni Agozzino;Wamadeva Balachandran;Maysam F. Abbod;Manickam Jayamurthy;Francesco Di Natale;David Brennen;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5845 - 5851
Publisher: IEEE
 
» Node Deployment Based on Extra Path Creation for Wireless Sensor Networks on Mountain Roads
Abstract:
Wireless sensor networks on mountain roads will form winding and long transmission paths and accordingly result in centralized energy dissipation near the sink and large transmission delay. In this letter, we propose a node deployment scheme to settle the above-mentioned thorny issues. The core idea is to construct extra paths to the sink and achieve data diversion. Specifically, the places with relatively large transmission hops to the sink and also comparatively small distance away from it are selected as the starting points of the extra paths. This selection mechanism contributes to alleviating the energy holes and reducing the transmission delay. Finally, experimental simulations show the effectiveness and superiority of our deployment scheme.
Autors: Xuxun Liu;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2376 - 2379
Publisher: IEEE
 
» Noise Equalization for Ultrafast Plane Wave Microvessel Imaging
Abstract:
Ultrafast plane wave microvessel imaging significantly improves ultrasound Doppler sensitivity by increasing the number of Doppler ensembles that can be collected within a short period of time. The rich spatiotemporal plane wave data also enable more robust clutter filtering based on singular value decomposition. However, due to the lack of transmit focusing, plane wave microvessel imaging is very susceptible to noise. This paper was designed to: 1) study the relationship between ultrasound system noise (primarily time gain compensation induced) and microvessel blood flow signal and 2) propose an adaptive and computationally cost-effective noise equalization method that is independent of hardware or software imaging settings to improve microvessel image quality.
Autors: Pengfei Song;Armando Manduca;Joshua D. Trzasko;Shigao Chen;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Nov 2017, volume: 64, issue:11, pages: 1776 - 1781
Publisher: IEEE
 
» Noise of a JFET Charge Amplifier for Piezoelectric Sensors
Abstract:
A comprehensive noise model of a junction gate field-effect transistor (JFET) charge amplifier is presented for applications with piezoelectric sensors. Based on this previously reported amplifier structure, a noise equivalent circuit is derived and discussed. Universal noise gain expressions for each of the twelve considered noise sources are given. By means of an analytical description of the charge amplifier’s noise behavior, the design and optimization of such preamplifiers for various capacitive microelectromechanical sensor systems will be distinctly simplified. Calculations of the noise floor are compared with measurements with a cantilever-type magnetoelectric sensor and with the performance of a so far commonly utilized basic charge amplifier. With the JFET charge amplifier a noise reduction of approximately 22 dB is achieved in the vicinity of the utilized sensor’s resonance frequency of 7.45 kHz. The reported amplifier is the first which has no negative influence on the total noise level of a resonant magnetoelectric sensor system.
Autors: Phillip Durdaut;Veronika Penner;Christine Kirchhof;Eckhard Quandt;Reinhard Knöchel;Michael Höft;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7364 - 7371
Publisher: IEEE
 
» Non-Binary LDPC Code Design for the Poisson PPM Channel
Abstract:
This paper investigates the design of non-binary protograph low-density parity-check codes for the Poisson channel with -ary pulse position modulation. The field order over which the code is constructed is matched to the pulse position modulation order yielding a coded modulation scheme. The optimization of the low-density parity-check code structure is performed via protograph density evolution on a surrogate -ary erasure channel. The surrogate design is illustrated to be not only accurate, but also robust for a range of practical values of channel background noise and various modulation orders. As a result the proposed codes show excellent performance over the Poisson channel with pulse position modulation outperforming competing schemes. As a side-product of this paper, finite-length benchmarks on the block error probability are provided, together with a union bound to characterize the code performance in the error floor region.
Autors: Balázs Matuz;Enrico Paolini;Flavio Zabini;Gianluigi Liva;
Appeared in: IEEE Transactions on Communications
Publication date: Nov 2017, volume: 65, issue:11, pages: 4600 - 4611
Publisher: IEEE
 
» Non-Binary Protograph-Based LDPC Codes for 2-D-ISI Magnetic Recording Channels
Abstract:
2-D inter-symbol-interference (2-D-ISI), consisting of ISI in the down track direction and inter-track interference along the cross-track direction, is a major factor that severely degrades the performance of ultra-high density magnetic recording systems. Due to its superior performance and the protograph structure which facilitates high-speed encoding and decoding, the protograph codes have shown a high potential to tackle 2-D-ISI. However, so far, no work has been reported on the design of non-binary protograph-based low-density parity-check (NP-LDPC) codes for 2-D-ISI channels. In this paper, we first propose a modified protograph extrinsic information transfer analysis. In conjunction with the asymptotic ensemble weight distribution analysis, they both serve as theoretical tools to analyze the performance of NP-LDPC codes designed for the 2-D-ISI channels. By further applying a fast search approach, we construct two types of NP-LDPC codes for 2-D-ISI channels. Both theoretical analyses and simulated results show that the proposed codes outperform the existing binary LDPC codes that optimized for 2-D-ISI channels as well as the non-binary quasi-cyclic LDPC code, at both low and high SNR regions.
Autors: Pingping Chen;Cai Kui;Lingjun Kong;Zaichun Chen;Mu Zhang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Non-Degeneracy and Effects of Pinning in Strongly Coupled Vortex Pairs
Abstract:
We study the effects of pinning on the quasi-static behavior of stacked, strongly coupled spin-vortex pairs in magnetic multilayered nanopillars, with vertical vortex separation small compared with the vortex-core size. The small separation causes the core–core interaction to be the dominant energy contribution for small applied fields and excitations, which results in highly non-linear dynamics. The properties of such a vortex pair are expected to only be dependent on the relative vortex core polarizations and relative chiralities, so that the individual configurations should be degenerated. We show how pinning can lift this degeneracy, which can be used to distinguish the individual chirality configurations.
Autors: Erik Holmgren;Artem Bodarenko;Björn Koop;Boris Ivanov;Vladislav Korenivski;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Non-Intrusive Energy Disaggregation Using Non-Negative Matrix Factorization With Sum-to-k Constraint
Abstract:
Energy disaggregation or non-intrusive load monitoring addresses the issue of extracting device-level energy consumption information by monitoring the aggregated signal at one single measurement point without installing meters on each individual device. Energy disaggregation can be formulated as a source separation problem, where the aggregated signal is expressed as linear combination of basis vectors in a matrix factorization framework. In this paper, an approach based on Sum-to-k constrained non-negative matrix factorization (S2K-NMF) is proposed. By imposing the sum-to-k constraint and the non-negative constraint, S2K-NMF is able to effectively extract perceptually meaningful sources from complex mixtures. The strength of the proposed algorithm is demonstrated through two sets of experiments: Energy disaggregation in a residential smart home; and heating, ventilating, and air conditioning components energy monitoring in an industrial building testbed maintained at the Oak Ridge National Laboratory. Extensive experimental results demonstrate the superior performance of S2K-NMF as compared to state-of-the-art decomposition-based disaggregation algorithms.
Autors: Alireza Rahimpour;Hairong Qi;David Fugate;Teja Kuruganti;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4430 - 4441
Publisher: IEEE
 
» Noncontact Electrical Permittivity Mapping and pH-Sensitive Films for Osseointegrated Prosthesis and Infection Monitoring
Abstract:
The objective of this paper is to develop a noncontact, noninvasive system for detecting and monitoring subcutaneous infection occurring at the tissue and osseointegrated prosthesis interface. It is known that the local pH of tissue can change due to infection. Therefore, the sensing system integrates two parts, namely, pH-sensitive thin films that can be coated onto prosthesis surfaces prior to them being implanted and an electrical capacitance tomography (ECT) algorithm that can reconstruct the spatial permittivity distribution of a region of space in a noncontact fashion. First, a thin film pH sensor was fabricated by spray coating, and tests confirmed that the film exhibited changes in its permittivity due to pH. Second, the ECT forward and inverse problems were implemented. Third, an aluminum rod was employed as a representative phantom of an osseointegrated prosthesis and then spray coated with the pH sensor. Finally, the film-coated phantom was immersed in different pH buffers, dried, and subjected to ECT interrogation and spatial permittivity reconstruction. The results validated that ECT was able to detect and localize permittivity variations correlated to pH changes.
Autors: Sumit Gupta;Kenneth J. Loh;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Nov 2017, volume: 36, issue:11, pages: 2193 - 2203
Publisher: IEEE
 
» Nonlinear Analytical Computation of the Magnetic Field in Reluctance Synchronous Machines
Abstract:
This paper deals with an analytical model of reluctance synchronous motor, able to consider both stator slotting effect and magnetic saturation in the stator and rotor iron paths. It joints the field distribution at the air gap to a lumped-parameter magnetic network. Local saturation factors are defined so as to adjust the flux-density distribution. The analytical approach exhibits great potentiality, since it is a formulation based on an harmonic study, and it is easily adaptable to any motor geometries. As an example, 36-slot 4-pole machine is analyzed, considering three flux barriers per pole. Finite element analysis confirms the results achieved by means of the analytical model.
Autors: Hanafy Mahmoud;Nicola Bianchi;Giacomo Bacco;Nicola Chiodetto;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5373 - 5382
Publisher: IEEE
 
» Nonlinear Frequency-Domain Analysis of the Transformation of Cortical Inputs by a Motoneuron Pool-Muscle Complex
Abstract:
Corticomotor coherence in the beta and/or gamma bands has been described in different motor tasks, but the role of descending brain oscillations on force control has been elusive. Large-scale computational models of a motoneuron pool and the muscle it innervates have been used as tools to advance the knowledge of how neural elements may influence force control. Here, we present a frequency domain analysis of a NARX model fitted to a large-scale neuromuscular model by the means of generalized frequency response functions (GFRF). The results of such procedures indicated that the computational neuromuscular model was capable of transforming an oscillatory synaptic input (e.g., at 20 Hz) into a constant mean muscle force output. The nonlinearity uncovered by the GFRFs of the NARX model was responsible for the demodulation of an oscillatory input (e.g., a beta band oscillation coming from the brain and forming the input to the motoneuron pool). This suggests a manner by which brain rhythms descending as command signals to the spinal cord and acting on a motoneuron pool can regulate a maintained muscle force. In addition to the scientific aspects of these results, they provide new interpretations that may further neural engineering applications associated with quantitative neurological diagnoses and robotic systems for artificial limbs.
Autors: Renato Naville Watanabe;André Fabio Kohn;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Nov 2017, volume: 25, issue:11, pages: 1930 - 1939
Publisher: IEEE
 
» Nonlinear Transceiver Designs for Full-Duplex MIMO Relay Systems
Abstract:
This paper investigates nonlinear transceiver design for full-duplex multiple-input multiple-output (FD-MIMO) relay systems. A dual-hop amplify-and-forward relaying protocol is considered. At the destination, nonlinear successive-interference-cancellation (SIC) is used for signal detection. The goal is to find the source and relay precoders such that the symbol-vector error rate (SVER) can be minimized. Due to the loop interference (LI), optimizing the relay precoder in FD systems is much more involved. In this paper, we propose novel designs to solve this problem. Starting from the QR-SIC receiver, we theoretically show that the relay precoder can be solved with a closed-form expression even when the system incurs LI. Then, we consider the system with a minimum mean-squared-error SIC receiver, where the relay precoder design entails a different problem formulation and introduces new challenges. We propose a novel iterative method, with closed-form solutions in each iteration, to solve this problem. Simulations show that our designs can significantly improve the SVER performance for FD-MIMO relay systems.
Autors: Chun-Tao Lin;Fan-Shuo Tseng;Wen-Rong Wu;Ronald Y. Chang;
Appeared in: IEEE Transactions on Communications
Publication date: Nov 2017, volume: 65, issue:11, pages: 4632 - 4645
Publisher: IEEE
 
» Novel Approach for the Reduction of Leakage Current Characteristics of 20 nm DRAM Capacitors With ZrO2–Based High-k Dielectrics
Abstract:
In order to produce a dynamic random access memory (DRAM) of 20 nm or less, the most important concern regarding development is to reduce the leakage current degradation of the capacitor using high-k dielectrics. We studied the effect of defect sources present after the formation of the capacitor and measured the leakage current characteristics of the capacitor using the dielectric breakdown degradation test, a test used in mass production. From these results, we confirmed that the leakage current degradation was completely eliminated by removing external impurities of boron and hydrogen without any change in the structure or materials of the capacitor. For further DRAM scaling, we propose a method of reducing leakage current degradation of the capacitor.
Autors: Jong-Min Lee;Dong-Sik Park;Seung-chul Yew;Soo-Ho Shin;Jun-Yong Noh;Hyoung-Sub Kim;Byoung-Deog Choi;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1524 - 1527
Publisher: IEEE
 
» Novel Differential Dielectric Waveguide Filter Using Spatial Coupling Mechanism
Abstract:
This letter presents a novel differential dielectric waveguide (DW) filter using a spatial coupling mechanism. The DW resonator operating in TE-mode is reasonably cut and applied to the design of compact differential filter. Different from the traditional DW filter, the coupling between the DW resonators can be fulfilled by placing the cut planes of the DW resonators face-to-face in an open space. Meanwhile, the proposed differential filter can work well whether the employed DW resonators have the common ground plane or not, leading to a high flexibility. For demonstration, two kinds of differential DW filters with and without the common ground plane are designed and measured, and their simulation and measured results are presented. Both of them showcase high performance, such as low insertion loss of the differential-mode passband and good common-mode suppression.
Autors: Yan-Yuan Zhu;Jian-Xin Chen;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Nov 2017, volume: 27, issue:11, pages: 971 - 973
Publisher: IEEE
 
» Novel Expressions and Applications for the Level Crossing Rate of Maximal Ratio Combining in the Presence of Cochannel Interferers
Abstract:
The level crossing rate (LCR) is an important second-order statistical quantity that characterizes the rate of occurrence of fading time intervals. In this paper, we investigate the LCR of multiantenna flat-fading channels in the presence of additive white Gaussian noise and cochannel interferers with unequal received powers and Doppler shifts. We first present a unified approach to derive the exact LCR of the signal-to-interference-noise ratio at a receiver, where maximum ratio combining is deployed over spatially correlated or uncorrelated systems. Through the exact LCR derivation, we identify an accurate approach to obtain a simplified approximate LCR expression in the spatially uncorrelated system case. Benefits of the LCR expressions derived in the paper are demonstrated in two important applications: 1) the packet error rate is evaluated through the finite-state Markov channel model; and 2) the optimum packet length to maximize the throughput of the system with the stop-and-wait automatic repeat request protocol is derived. The analytical results are validated by simulations.
Autors: Ahmed O. D. Ali;Cenk M. Yetis;Murat Torlak;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9793 - 9808
Publisher: IEEE
 
» Novel Heteropolar Radial Hybrid Magnetic Bearing With Low Rotor Core Loss
Abstract:
In this paper, one novel heteropolar radial hybrid magnetic bearing (HRHMB) is proposed for flywheel energy storage system. First, its structure and working principle are introduced in detail. Then, its fundamental equations are derived based on magnetic circuit model, such as displacement stiffness, current stiffness, and load capacity. Furthermore, its suspension performance and magnetic coupling are analyzed based on the 2-D finite-element analysis. Finally, the comparison of main performance indexes between the proposed HRHMB and conventional one under the same constraints is made. It indicates that the displacement stiffness can be reduced by the novel structure. In addition, the rotor core loss of the novel HRHMB is just 22.53 W, which is only 41.6% of the conventional eight-pole HRHMB with the same load capacity.
Autors: Runze Zhu;Wei Xu;Caiyong Ye;Jianguo Zhu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Novel Hybrid-Flux-Path Moving-Iron Linear Oscillatory Machine With Magnets on Stator
Abstract:
While having various desired merits of high structural robustness and thus reliability, high thrust density, low fabrication cost, and so on, the stator-magnet moving-iron transverse-flux linear oscillatory machine suffers from high consumption of rare-earth magnetic material (high material cost) and heavy flux leakage at the stator outer region (underutilization of permanent magnets). To mitigate the demerits, a novel stator-magnet moving-iron transversal-flux hybrid-flux-path linear oscillatory machine (SMTHLOM), with additional back iron and auxiliary radially magnetized ferrite magnets, is proposed in this paper. The topology and operational principle of the proposed SMTHLOM are explained in detail. The 3-D finite-element analysis is introduced to investigate the sensitivities of main structural parameters, which enables the selection of optimal dimensions. Based on a set of comparison rules, a comprehensive comparison was conducted between these two topologies on various key indicators, such as the back electromotive force, thrust, and thermal distribution. The simulation results show that the SMTHLOM is low cost and small stator outer flux leakage, and thus is more suitable for some applications, e.g., fridge compressors, requiring low cost and high thrust density.
Autors: Xiang Li;Wei Xu;Caiyong Ye;Jianguo Zhu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Novel Neutron Detector Material: Microcolumnar LixNa1–xI:Eu
Abstract:
Current neutron detection relies on 3He detectors, which are prone to material shortages, and suffer from poor spatial resolution. Such inadequacies make 3He unsuitable for new applications in state-of-the-art spallation sources such as the Spallation Neutron Source at Oak Ridge National Laboratory. Here, we report on the synthesis and application of a novel scintillator material for neutron detection: a mixed halide compound, Eu-doped (0.05 mol. %) 6LixNa1–x (6LNI:Eu). 6LNI:Eu is a bright and efficient scintillator that can be grown in large format, thin films that exhibit microcolumnar structure in their cross section. The ability to grow in a microcolumnar structure means that a resolution of approximately 1 lp/mm can be achieved with neutrons using an electron-multiplying charge coupled device camera, thereby conferring an advantage over other solid (not gaseous) neutron scintillators, such as Cs26LiYCl6:Ce (CLYC) and GS20. The large area format of 6LNI:Eu is a significant advantage for detecting specular reflections in neutron scattering experiments. Moreover, the microcolumnar nature of films permits high-resolution imaging when films are coupled to a-Si:H flat panels, CCD, or CMOS readouts. While not the primary focus, this also makes them suitable for digital neutron radiography. Enriched 6Li was used to increase the neutron absorption cross section of the thin films, while preserving the brightness of the scintillation response. Here, we describe the vapor deposition techniques used to fabricate the 6LNI:Eu scintillator screens and report on the test results. The films were tested at the High Flux Isotope Reactor (HFIR) at ORNL. An efficiency of approximately 43% for 4.1-Å neutrons with a resolution of 650 <- nline-formula> $mu text{m}$ was measured for a 375- thick film of 6LNI:Eu using a neutron sensitive Anger camera.
Autors: Matthew S. J. Marshall;Mitali J. More;Harish B. Bhandari;Richard A. Riedel;Shane Waterman;John Crespi;Peter Nickerson;Stuart Miller;Vivek V. Nagarkar;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: Nov 2017, volume: 64, issue:11, pages: 2878 - 2882
Publisher: IEEE
 
» Novel Operation of a Multi-Bit SOT Memory Cell Addressed With a Single Write Line
Abstract:
Spin–orbit torque (SOT) originates from the spin–orbit interaction of non-magnetic heavy metals (HMs), allowing for an electrical manipulation of perpendicular magnetization in HM/ferromagnet (FM)/oxide structures. In this paper, we experimentally demonstrate the SOT-induced switching of two FM bits addressed with a single write line. We fabricate a device consisting of two perpendicularly magnetized Ta/CoFeB/MgO structures with a common Ta underlayer, in which the magnetization directions of the two FM bits could be concurrently controlled by injecting a single current pulse. This suggests that multiple bits in SOT-based devices can be written as either “0” or “1” at the same time. Moreover, the selective switching of a specific bit is achieved by differentiating the critical switching currents between the two FM bits, which is crucial in demonstrating multi-level cell SOT memory. Our results provide an efficient writing mechanism, enabling wider applications of SOT-based spintronic devices.
Autors: Seung-heon Chris Baek;Young-Wan Oh;Byong-Guk Park;Mincheol Shin;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Novel Pixel Circuit Using Coupling Method to Achieve High Driving Voltage for Blue-Phase LCDs
Abstract:
This paper presents a new pixel circuit that uses amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs) for use in in-plane switching blue-phase liquid-crystal displays (IPS BPLCDs). The proposed pixel circuit has a simple structure that involves only three TFTs and two capacitors. To drive the high transmittance of the BPLCs, the coupling mode with a two-voltage-level signal is designed to produce a higher operating voltage. To confirm the feasibility of the proposed pixel circuit, the electrical characteristics of a fabricated a-IGZO TFT are measured and used to construct the RPI simulation model in HSPICE. Simulation results demonstrate that the maximum operating voltage is 29.884 V with an input data voltage of 15 V, so the required voltage of high transmittance of BPLCs is achieved.
Autors: Chih-Lung Lin;Po-Cheng Lai;Mao-Hsun Cheng;Po-Chun Lai;Chia-Lun Lee;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4768 - 4771
Publisher: IEEE
 
» Novel Relay Selection Strategies for Cooperative NOMA
Abstract:
In this paper, we consider non-orthogonal multiple access (NOMA) relaying networks, where one base station communicates with two mobile users with the aid of multiple relays. We propose a two-stage relay selection strategy for NOMA networks with decode-and-forward (DF) and amplify-and-forward (AF) relaying protocols with different quality of service requirements at the users, respectively. Then, the outage probabilities of the NOMA two-stage DF and AF schemes are obtained in closed-form expressions, and the diversity order is determined based on their asymptotic expressions at high signal-to-noise ratio. Both of the developed analytical results and carried out computer simulations show that NOMA two-stage DF (AF) relaying is superior to existing relay selection strategies developed for cooperative NOMA and orthogonal multiple access networks.
Autors: Zheng Yang;Zhiguo Ding;Yi Wu;Pingzhi Fan;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10114 - 10123
Publisher: IEEE
 
» Novel Superjunction LDMOS (>950 V) With a Thin Layer SOI
Abstract:
A novel superjunction (SJ) lateral double-diffused MOSFET (>950 V) with a thin layer SOI combining the advantage of low specific on-resistance of the SJ and the high breakdown voltage of the thin SOI is proposed and experimentally demonstrated in this letter. Based on our previously developed equivalent substrate model, the optimized SJ endows the device with a respectably reduced without sacrificing . Meanwhile, the thin layer SOI is designed with the enhanced dielectric layer field principle to carry out a high . The experimental results exhibit a of 145 cm2 with a of 977 V. This represents a reduction in by 18.1% when compared with the theoretical “silicon limit”.
Autors: Wentong Zhang;Zhenya Zhan;Yang Yu;Shikang Cheng;Yan Gu;Sen Zhang;Xiaorong Luo;Zehong Li;Ming Qiao;Zhaoji Li;Bo Zhang;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1555 - 1558
Publisher: IEEE
 
» Novel Tunable Ultrashort Pulse Generator With High Amplitude and Low Ringing Level
Abstract:
A new design of the ultrashort pulse generator based on a step recovery diode (SRD) is presented in this letter. The design schematic features allow us to increase the pulse amplitude, decrease the ringing level, and realize pulse duration tuning. The signal amplitude increase results from the use of an additional inductive energy storage, which accumulates energy of the magnetic field during both charge storing and extraction phases of the generator duty cycle. The ringing level is reduced by including the ringing reduction subcircuit in the design. This subcircuit consists of the Schottky diode to block the negative half-waves of ringing oscillation and the resistor to force oscillation fading. The electronic tuning of the pulse duration is based on the relation between the SRD recovery time and the forward current. In the experiments ultrashort pulses with the duration in a range from 350 ps to 1.5 ns and the 40-V amplitude were obtained for a 50- load by varying the diode forward current. The output signal has a good symmetry shape, which is shown both in simulation and experimentally. The measured ringing level was −20.5 dB.
Autors: A. M. Bobreshov;A. S. Zhabin;V. A. Stepkin;G. K. Uskov;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Nov 2017, volume: 27, issue:11, pages: 1013 - 1015
Publisher: IEEE
 
» Novel Wire-Grid Nano-Antenna Array With Circularly Polarized Radiation for Wireless Optical Communication Systems
Abstract:
A new circularly polarized wire-grid nano-antenna array designed for optical telecommunication applications is proposed in this paper. The array consists of two groups of radiators, which are orthogonal to each other. Each group consists of six aligned radiators connected via nonradiating connectors. A 90° phase shift is achieved by inserting a gap between the feeding coupling rods and the inner radiators of one of the two antenna groups. The antenna is characterized by its high directivity (10.8 dBi) and a wide axial ratio bandwidth, which covers the range from 188.2 to 197.8 THz. The radiation efficiency of the antenna is 82.75% at 193.55 THz with very small variations along its operating bandwidth. Such good radiation characteristics are very attractive for optical communication applications.
Autors: Mai O. Sallam;Guy A. E. Vandenbosch;Georges G. E. Gielen;Ezzeldin A. Soliman;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4700 - 4706
Publisher: IEEE
 
» Nowcasting of Earthquake Consequences Using Big Social Data
Abstract:
Messages posted to social media in the aftermath of a natural disaster have value beyond detecting the event itself. Mining such deliberately dropped digital traces allows a precise situational awareness, to help provide a timely estimate of the disaster’s consequences on the population and infrastructures. Yet, to date, the automatic assessment of damage has received little attention. Here, the authors explore feeding predictive models by tweets conveying on-the-ground social sensors’ observations, to nowcast the perceived intensity of earthquakes.
Autors: Marco Avvenuti;Stefano Cresci;Mariantonietta N. La Polla;Carlo Meletti;Maurizio Tesconi;
Appeared in: IEEE Internet Computing
Publication date: Nov 2017, volume: 21, issue:6, pages: 37 - 45
Publisher: IEEE
 
» Nuclear Norm-Based 2DLPP for Image Classification
Abstract:
Two-dimensional locality preserving projections (2DLPP) that use 2D image representation in preserving projection learning can preserve the intrinsic manifold structure and local information of data. However, 2DLPP is based on the Euclidean distance, which is sensitive to noise and outliers in data. In this paper, we propose a novel locality preserving projection method called nuclear norm-based two-dimensional locality preserving projections (NN-2DLPP). First, NN-2DLPP recovers the noisy data matrix through low-rank learning. Second, noise in data is removed and the learned clean data points are projected on a new subspace. Without the disturbance of noise, data points belonging to the same class are kept as close to each other as possible in the new projective subspace. Experimental results on six public image databases with face recognition, object classification, and handwritten digit recognition tasks demonstrated the effectiveness of the proposed method.
Autors: Yuwu Lu;Chun Yuan;Zhihui Lai;Xuelong Li;Wai Keung Wong;David Zhang;
Appeared in: IEEE Transactions on Multimedia
Publication date: Nov 2017, volume: 19, issue:11, pages: 2391 - 2403
Publisher: IEEE
 
» Numerical Analysis and Optimization of Miniature Electrohydrodynamic Air Blowers
Abstract:
As the demand for advanced microelectronic devices of small form factor and high power density has increased, the capability of the miniaturized mechanical solutions for effective cooling has become critical. Electrohydrodynamic (EHD) air blowers have great potential as alternative cooling solutions over the traditional mechanical systems to meet the thermal management requirements with flexible design and considerable flow production for effective heat removal. In this paper, a numerical analysis and optimization of wire-to-plane EHD air blowers are performed based on 2-D developed models validated against previous data. For a range of blower heights from 2 to 10 mm, the location and length of the collecting plane located at the blower walls apart from the emitter wire electrode are investigated and optimized based on pumping efficiency using the ranges of fixed operating powers and voltages. Simple relations for each optimization method are presented to determine the optimal blower configuration. Results of flow rate and static pressure obtained by each optimized blower show good agreement with those predicted by EHD scaling laws previously presented.
Autors: Abdulmajeed A. Ramadhan;Nikil Kapur;Jonathan L. Summers;Harvey M. Thompson;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 3007 - 3018
Publisher: IEEE
 
» Numerical Investigation of the Surface Wave Formation in a Microwave Plasma Torch
Abstract:
The microwave plasma torch (MPT) is an attractive plasma source in both industry and scientific research because of its advantages in electrodeless operation ability, high energy efficiency, and flexibility under different operational conditions. However, relatively few numerical studies have been carried out for the MPT fed by a rectangular waveguide in two or even three dimensions. Therefore, this paper presents a 2-D, axisymmetric, and stationary fluid models to characterize the MPT, with an emphasis on the mechanism of the surface wave formation and the sustentation of the plasma column. Nine partial differential equations are included in this research, coupling microwave radiation, heat transfer, plasma bulk flow, and transport of different species with each other. The obtained results reveal how the traveling surface wave occurs and elucidate the consequent influence of the surface wave formation. Furthermore, this paper demonstrates the extension of the plasma column length and the propagation of the surface wave with an increase in the total plasma-absorbed microwave power. The dependence of the plasma column length on the plasma-absorbed microwave power is found to be motivated by the surface wave propagation. The limitations of the model and the difficulties in its numerical implementation are also discussed in the paper.
Autors: Wencong Zhang;Junwu Tao;Kama Huang;Li Wu;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 2929 - 2939
Publisher: IEEE
 
» Numerical Simulation of Plasma Near the Cathode Spot of Vacuum Arc
Abstract:
Kinetic numerical simulation of plasma near the cathode spot (CS) was performed. Two types of possible solutions for the self-sustained CS on copper cathode were found. The firs type of solutions is valid for quasi-stationary spot with radius of about . Stationary solution in this case is possible with cathode temperature 4.2–4.5 kK, current density A/cm2, and applied voltage 20–25 V. The second type of solution is obtained for the spot with radius of and spherical geometry of plasma expansion. Possible solutions were obtained for the cathode temperature of above 6.2 kK, current density of about A/cm2 and applied voltage of 15–25 V. Transient simulations of the near-cathode plasma expansion have shown that if current density remains less than A/cm2 then the plasma expansion has a “quiet” self-similar character. At higher current density the plasma expansion has an essentially nonstationary character. The high-density current leads first to the development of Buneman instability and second to the plasma rupture with the creation of conditions for collective acceleration of ions toward the cathode and toward the anode. The accelerated ions create an additional powerful heat flux to the cathode, which should facilitate the reproduction of the CSs in the spark stage of vacuum discharge.
Autors: Dmitry L. Shmelev;Sergey A. Barengolts;Mikhail M. Tsventoukh;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 3046 - 3053
Publisher: IEEE
 
» Numerical Study on a Novel Curie Temperature Controlled Hybrid Thermo-Magnetic Structure for Magnetic Random Access Memories
Abstract:
High thermal stability, a fast switching time, and a low switching current are key characteristics of merit for realizing gigabit-class magnetic random access memory (MRAM). Especially, the switching current needs to be reduced significantly for creating high-density MRAM. In order to realize these necessary features, a number of magnetic tunnel junction (MTJ) structures have been proposed. A previous study of ours led to the proposal of a novel Curie-temperature-controlled hybrid thermo-magnetic structure for MRAM, for the purpose of improving these advantageous properties. This paper presents an analysis of the switching time and switching current by using micromagnetic simulation techniques for comparing our structures with various MTJ structures that have been proposed recently. We confirm that our novel structure can improve the switching characteristics of MRAM. The results of our analysis revealed that a 44% lower switching current and a 32% faster switching time can be achieved compared with the conventional structure.
Autors: Ken Machida;Yoshiaki Sonobe;Yoshinobu Nakatani;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» O-MAC: Opportunistic MAC Protocol for M2M Communication in WiFi White Spaces
Abstract:
Machine-to-machine (M2M) communication comprises of autonomous devices communicating with each other without human intervention. The explosive growth in devices using an M2M communication and the shortage of spectrum has made network access for such devices a challenging problem. While M2M communication in the unlicensed bands is attractive from an economic perspective, such bands are also under use by existing technologies, such as WiFi. In this letter, we propose a new opportunistic medium access control protocol to allow an M2M communication within white spaces (i.e., periods without traffic) of WiFi networks. The proposed protocol increases the effective utilization of the channel without any significant impact on existing WiFi networks.
Autors: Ajinkya Rajandekar;Biplab Sikdar;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2440 - 2443
Publisher: IEEE
 
» Object Detection Using Convolutional Neural Networks in a Coarse-to-Fine Manner
Abstract:
Object detection in remote sensing images has long been studied, but it remains challenging due to the diversity of objects and the complexity of backgrounds. In this letter, we propose an object detection method using convolutional neural networks (CNNs) in a coarse-to-fine manner. In the coarse step, coarse candidate regions that may contain objects are proposed. In the fine step, fine candidate regions are cropped from coarse candidate regions, and are classified as objects or backgrounds. We design a concise and efficient framework that can propose fewer candidate regions and extract more discriminative features. The framework consists of two eight-layer CNNs that are well designed and powerful. To use CNNs to detect inshore ships, image samples are required, each of which should contain only one ship. However, the traditional image cropping method cannot generate such samples. To solve this problem, we present an orientation-free image cropping method that can generate trapezium rather than rectangle samples, making inshore ship detection by CNN feasible. Experimental results on Google Earth images demonstrate that the proposed method outperforms existing state-of-the-art methods.
Autors: Xiaobin Li;Shengjin Wang;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2037 - 2041
Publisher: IEEE
 
» Object Tracking Using Multiple Features and Adaptive Model Updating
Abstract:
Correlation filter-based tracking methods have been intensively investigated for their high efficiency and robustness. However, a single feature-based tracker cannot adapt to challenging situations, such as severe deformation, rotation, and illumination variations. Besides, a simple linear interpolation-based model updating mechanism is prone to model degradation, and consequently tracker drifting. In this paper, a 2-D location filter is combined with a 1-D scale filter to jointly estimate the state of object under tracking, and three complementary features are integrated to further enhance the overall tracking performance. Besides, we define a penalty factor for adaptive model updating, to achieve a balance between stability and flexibility, especially when the object is under occlusion. Extensive experiments have been conducted on four large-scale data sets, namely, the object tracking benchmark, VOT15, Temple-Color128, and the UAV123 tracking benchmark. Quantitative and qualitative results show that our proposed tracker achieves promising results in terms of tracking accuracy, robustness, and speed as compared with other popular trackers, and is highly suitable for real-time applications, such as unmanned aerial vehicles. It outperforms the state-of-the-art methods under different nuisances, including scale variation, deformation, occlusion, rotation, and out-of-view.
Autors: Qingyong Hu;Yulan Guo;Zaiping Lin;Wei An;Hongwei Cheng;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2882 - 2897
Publisher: IEEE
 
» Object-Level Motion Detection From Moving Cameras
Abstract:
It is important for a moving observer to be able to identify his/her surrounding objects and determine whether these objects are moving or stationary, which is called object-level motion detection. Detecting object-level motion from moving cameras is a difficult problem to solve for collision-free navigation due to the dual motion introduced by the mixture of the camera motion and the object motion. This paper presents a novel technique that detects object-level motion from a freely moving camera using only two consecutive video frames. A context-aware motion descriptor (CMD) is designed based on the object’s moving speed and moving direction relative to that of the moving camera. The CMD employs the contextual information, e.g., the optical flow of the image background surrounding the moving object of interest, which describes the object motion behavior better than other contexts such as the camera’s GPS and direction. The inconsistency between the histogram of oriented optical flow of the object and its surrounding background is measured for the object-level motion detection. The proposed technique has been evaluated over two types of widely studied objects, i.e., vehicles and humans that are captured with different sizes, moving speeds, and image backgrounds using a moving camera. Experiments on challenging real-world videos show promising performance in object-level motion detection.
Autors: Tao Chen;Shijian Lu;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Nov 2017, volume: 27, issue:11, pages: 2333 - 2343
Publisher: IEEE
 
» Observability of Multi-Agent Systems With Switching Topology
Abstract:
This brief studies the observability of multi-agent systems with switching topology. First, we consider the first-order multi-agent systems. Then, we prove that the multi-agent system with switching topology is observable if each subgraph is weakly connected. It is shown that the multi-agent system with switching topology can be observable even if each of its subsystems is not observable. Second, we establish graphical conditions for the observability of multi-agent systems with general linear dynamics. Finally, an example is given to demonstrate the effectiveness of the theoretical result.
Autors: Zehuan Lu;Lin Zhang;Long Wang;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Nov 2017, volume: 64, issue:11, pages: 1317 - 1321
Publisher: IEEE
 
» Observation of Magnetoresistance Effect in $n$ -Type Non-Degenerate Germanium With Co2Fe0.4Mn0.6Si Heusler Alloy Electrodes
Abstract:
The local 3-terminal magnetoresistance properties of n-Ge/MgO/Co2Fe0.4Mn0.6Si lateral spin-valve devices were systematically investigated. In the spin extraction condition, clear steep voltage changes were successfully observed. We measured the bias voltage and temperature dependences of the spin resistance-area product. At a high bias voltage, the spin signal increased with increasing voltage, reaching a maximum value of at mV. The signal decreased with increasing temperature but was still observed up to 160 K.
Autors: Takeo Koike;Mikihiko Oogane;Tetsurou Takada;Hidekazu Saito;Yasuo Ando;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Observation of Mode Competition in Operation of a 420 GHz, TE17.4 Second Harmonic Gyrotron With Complex Cavity
Abstract:
The lack of terahertz sources, especially the high-power ones, is one of the main obstacles in the developments of terahertz science and technology. A gyrotron, based on the electron cyclotron masers, is one of the most promising sources to generate high-power terahertz radiation. Therefore, a 0.42-THz gyrotron with a gradually tapered complex cavity operating at the second harmonic is designed and experimentally tested in this paper. Experimental results show that the designed gyrotron can generate high-power THz radiation of 19.2 kW at 0.42 THz with the beam voltage of 51 kV, beam current of 4.4 A and the external magnetic field of 8.03 T, corresponding to an efficiency of 8.6%. By comparison with theoretical results, it can be shown that the operating mode in the designed gyrotron is confirmed as the TE17.4 mode. At the same time, the excitation of the fundamental TE0.5 mode is also observed in the experiment when the beam current is increased to 7.3 A, where the operating frequency is 216.143 GHz. Through extensive experimental efforts, it is found that the designed gyrotron can operate stably at the desired TE17.4 mode when the beam current is in the range of 3–7 A.
Autors: Qixiang Zhao;Sheng Yu;Tianzhong Zhang;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4700 - 4705
Publisher: IEEE
 
» Observer-Based Control for Piecewise-Affine Systems With Both Input and Output Quantization
Abstract:
This technical note is concerned with the problem of simultaneous design of observers and controllers for a class of piecewise-affine systems against signal quantization occurring in both measurement output and control input channels. The general scenario is considered that system state and estimated state may not be in the same operating region. By a novel quantization-error-dependent Lyapunov function, the stability and performance criteria are first established for the augmented system composed of a closed-loop control system and an estimation error system with the aid of -procedure involving the region partition information of the original system. Then, by the cone complementary linearization algorithm, the desired observer and controller gains are solved simultaneously such that the resulting closed-loop system is asymptotically stable with a prescribed performance index. Finally, a networked single-link robot arm is utilized to demonstrate the effectiveness of the proposed control strategy.
Autors: Lixian Zhang;Zepeng Ning;Wei Xing Zheng;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5858 - 5865
Publisher: IEEE
 
» Observer-Based Control of 2-D Markov Jump Systems
Abstract:
This brief is concerned with the problem of asynchronous observer-based control for 2-D Markov jump systems (MJSs). Based on a linear matrix inequality setting, some equivalent criteria are proposed to ensure that the closed-loop hidden MJS is stochastically stable. On the basis of the derived stability conditions, the design problem of asynchronous observer-based controllers is addressed. The effectiveness of the design scheme is verified by a practical example in thermal process models.
Autors: Le Van Hien;Hieu Trinh;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Nov 2017, volume: 64, issue:11, pages: 1322 - 1326
Publisher: IEEE
 
» Obtaining Microscopic Images Under a High 20-T Pulse Magnetic Field Using an Optimized Coil
Abstract:
We optimized the coil of a pulsed electromagnet to be able to obtain dynamically microscopic images of crystals in a pulsed magnetic field of a maximum intensity of 20 T and pulsewidth of 3 ms. The pulsed field induces an eddy current that influences the nearby apparatus and objective lens made up of a conducting non-magnetic material. Developing a much shorter length of coil was required, because the working distance of the objective lens was incapable of preventing eddy currents. We calculated the maximum field and pulsed width; as a result, a coil wound with wire of 1-mm diameter in ten layers gives an ideal shape of the magnetic field when using a 10-mF capacitor bank with charge voltage of 700 V. Wound to the prescribed coil parameter values, the coil performed as expected. We demonstrate its performance with microscopic images taken using the optimized coil of the dynamic orientational behavior of diamagnetic monosodium urate crystals suspended in aqueous solution. The lying down of the acicular crystals through magnetic orientation just after application of the pulse field was observed dynamically.
Autors: Atom Hamasaki;Yuka Takeuchi;Sumio Ozeki;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Ocean and Geothermal Energy Systems
Abstract:
This paper presents techno–economic summaries of ocean wave, tidal and current, ocean thermal, and geothermal energy, including grid interface characteristics. These forms of energy represent a significant opportunity to complement diversified energy conversion portfolios. Ocean wave energy conversion relies on the capture of kinetic and potential energy in moving and elevated water in an ocean wave. Tidal and current technology converts the kinetic energy in moving water, much like a wind turbine. Ocean thermal converts the energy available in the temperature gradient of warm surface water and cold deep water. Last, geothermal conversion utilizes the hot rock and water deep within the Earth. The total global average wave resource is estimated at approximately 2000 GW, with approximately 300 GW in the United States. The total global tidal resource is estimated at approximately 1000 GW, with 50 GW in the United States. The marine current resource estimate for the Florida Current in the southeast United States is estimated at 5 GW. Ocean thermal has a global capacity estimate of 5000 GW. Last, the global conventional hydrothermal geothermal capacity estimate is approximately 200 GW, but with much more possible through enhanced geothermal systems. For cost, it was found that the long-term projected wave energy conversion cost is $0.10–0.15/kWh. The long-term projected tidal cost is found to be $0.025–0.25/kWh. Ocean thermal long-term cost is projected at $0.10–0.18/kWh. And last, geothermal, being more closely aligned with traditional thermal generation, is estimated at $0.03/kWh to $0.15/kWh.
Autors: Annette von Jouanne;Ted K. A. Brekken;
Appeared in: Proceedings of the IEEE
Publication date: Nov 2017, volume: 105, issue:11, pages: 2147 - 2165
Publisher: IEEE
 
» Ocean Surface Current Inversion Method for a Doppler Scatterometer
Abstract:
The ocean surface current is a very important parameter of ocean dynamic environment. It is connected to global climate change, marine environment forecasting, marine navigation, engineering security, and so on. The observation and prediction of ocean surface current have attracted more and more concern. Doppler Scatterometer (DopScat) is a new type of radar for ocean surface wind and current field remote sensing. The ocean surface current inversion method of DopScat impacts the measurement accuracy directly. In this paper, we establish the simulation model of a DopScat and provide the radial velocity error model. The numerical ocean surface Doppler spectrum model is also introduced and validated with the empirical geophysical model function in C-band (CDOP). The suitable ocean wave elevation spectrum and directional distribution function are selected. What is more, this paper establishes the maximum likelihood estimation (MLE) method to retrieve the ocean surface current and wind simultaneously. The retrieval accuracy for different positions in cross track, different wind speeds, and different current speeds are analyzed. At last, the global ocean current field is observed by DopScat and the ocean current is retrieved. In our simulation, the orbit parameters and observation geometry of DopScat are the same as that of HY-2A scatterometer. The retrieval results show that global current speed standard deviation can be smaller than 0.18 m/s for five days and grid average.
Autors: Qingliu Bao;Mingsen Lin;Youguang Zhang;Xiaolong Dong;Shuyan Lang;Peng Gong;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6505 - 6516
Publisher: IEEE
 
» OFDM Without CP in Massive MIMO
Abstract:
We study the possibility of removing the cyclic prefix (CP) overhead from orthogonal frequency division multiplexing (OFDM) in massive multiple-input multiple-output (MIMO) systems. We consider the uplink transmission, while our results are applicable to the downlink as well. The absence of CP increases the spectral efficiency in expense of intersymbol interference and intercarrier interference. It is known that in massive MIMO, the effects of uncorrelated noise and multiuser interference vanish as the number of base station antennas tends to infinity. To investigate if the channel distortions in the absence of CP fade away, we study the performance of the standard maximum ratio combining receiver. Our analysis reveals that in this receiver, there always remains some residual interference leading to saturation of signal-to-interference-plus-noise ratio. To resolve this problem, we propose using the time reversal (TR) technique. Moreover, in order to further reduce the multiuser interference, we propose a zero-forcing equalization to be deployed after the TR combining. We compare the achievable rate of the proposed system with that of the conventional CP-OFDM. We show that in realistic channels, a higher spectral efficiency is achieved by removing the CP from OFDM, while reducing the computational complexity.
Autors: Amir Aminjavaheri;Arman Farhang;Ahmad Rezazadehreyhani;Linda E. Doyle;Behrouz Farhang-Boroujeny;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7619 - 7633
Publisher: IEEE
 
» Off-Body Antenna Wireless Performance Evaluation in a Residential Environment
Abstract:
Modern body-centric communication systems require good link quality. Antenna performance is of primary importance when meeting this requirement. This paper contributes a method suited to the difficult task of quantifying antenna performance in a body-centric communications system. In a case study, a planar wrist wearable antenna, which provides radiation pattern switching across the 2.4 GHz operating band through an innovative technique that does not require an additional switching mechanism, is benchmarked against a monopole and a patch antenna in a residential setting. The performance of the antenna and subsequently the benefits of the pattern-switching technique are successfully quantified. The holistic method includes both antenna measurements and channel simulation with ray tracing. Results are verified against real-world measurements.
Autors: Sema Dumanli;Lawrence Sayer;Evangelos Mellios;Xenofon Fafoutis;Geoffrey S. Hilton;Ian J. Craddock;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6076 - 6084
Publisher: IEEE
 
» Off-grid electricity projects are starved for funds [News]
Abstract:
Despite innovative off-grid technology and high-profile initiatives, electrification in sub-Saharan Africa still trails population growth. In 2009 there were 585 million people in the region without power. Five years later, that figure had risen to 632 million, according to the latest International Energy Agency statistics.
Autors: Peter Fairley;
Appeared in: IEEE Spectrum
Publication date: Nov 2017, volume: 54, issue:11, pages: 12 - 12
Publisher: IEEE
 
» OLT energy savings via software-defined dynamic resource provisioning in TWDM-PONs
Abstract:
Time and wavelength division multiplexed passive optical network (TWDM-PON) standards dramatically increase the performance of PON systems and address ever-increasing demands for bandwidth. However, these schemes increase the complexity and energy consumption of PON systems because they exploit multiple wavelengths, which requires multiple transceivers in the optical line terminal (OLT). In this paper, we propose to integrate software-defined networking (SDN) into standard PON architectures to facilitate an orchestrated energy-efficient operation in which the SDN controller dynamically provisions the number of wavelengths, link-rates, and timeslot assignments depending on the global traffic conditions. The simulation results show that the proposed architecture and mechanism improves the energy-saving performance of OLTs if the traffic load is less than 80%, while guaranteeing the quality of service requirements in terms of the mean packet delay, jitter, queue length, throughput, and packet loss ratio.
Autors: Andrew Fernando Pakpahan;I-Shyan Hwang;AliAkbar Nikoukar;
Appeared in: IEEE/OSA Journal of Optical Communications and Networking
Publication date: Nov 2017, volume: 9, issue:11, pages: 1019 - 1029
Publisher: IEEE
 
» On a Class of Optimization-Based Robust Estimators
Abstract:
In this paper, we consider the problem of estimating a parameter matrix from observations which are affected by two types of noise components: (i) a sparse noise sequence which, whenever nonzero can have arbitrarily large amplitude (ii) and a dense and bounded noise sequence of “moderate” amount. This is termed a robust regression problem. To tackle it, a quite general optimization-based framework is proposed and analyzed. When only the sparse noise is present, a sufficient bound is derived on the number of nonzero elements in the sparse noise sequence that can be accommodated by the estimator while still returning the true parameter matrix. While almost all the restricted isometry-based bounds from the literature are not verifiable, our bound can be easily computed through solving a convex optimization problem. Moreover, empirical evidence tends to suggest that it is generally tight. If in addition to the sparse noise sequence, the training data are affected by a bounded dense noise, we derive an upper bound on the estimation error.
Autors: Laurent Bako;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5990 - 5997
Publisher: IEEE
 
» On Control Lyapunov–Razumikhin Functions, Nonconstant Delays, Nonsmooth Feedbacks, and Nonlinear Sampled-Data Stabilization
Abstract:
A methodology for the design of stabilizers in the sample-and-hold sense for nonlinear retarded systems is provided. The methodology is based on control Lyapunov–Razumikhin functions. Fully nonlinear retarded systems with an arbitrary number of arbitrary time-varying time-delays of discrete and distributed type are covered by the theory developed here, as long as the map describing the dynamics is uniformly in time Lipschitz on bounded sets of the Banach state space and the Euclidean input space. The standard assumption that all involved time-delay signals are globally Lipschitz is introduced. It is assumed, for the system at hand, that there exist a control Lyapunov–Razumikhin function and a suitably defined induced steepest descent state feedback. Moreover, such state feedback has to satisfy a suitably weak Lipschitz property, uniformly in time and in any bounded subset of the Banach state space. Such weak Lipschitz property has the advantage to allow for discontinuities in the feedback, which arise, for instance, in sliding-mode control methodologies. The following fact is shown: the above steepest descent state feedback is a stabilizer in the sample-and-hold sense, that is, such feedback, if applied by suitably fast sampling and holding, guarantees practical semiglobal stability of the closed-loop system, with arbitrary small final target ball of the origin. The problem of nonavailability in the buffer device of past values of the system internal variables is solved by spline approximation methods, even in the case discontinuities arise in the state feedback.
Autors: Pierdomenico Pepe;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5604 - 5619
Publisher: IEEE
 
» On Distributed Computing for Functions With Certain Structures
Abstract:
The problem of distributed function computation is studied, where functions to be computed is not necessarily symbol-wise. A new method to derive a converse bound for distributed computing is proposed; from the structure of functions to be computed, information that is inevitably conveyed to the decoder is identified, and the bound is derived in terms of the optimal rate needed to send that information. The class of informative functions is introduced, and, for the class of smooth sources, the optimal rate for computing those functions is characterized. Furthermore, for i.i.d. sources with joint distribution that may not be full support, functions that are composition of symbol-wise function and the type of a sequence are considered, and the optimal rate for computing those functions is characterized in terms of the hypergraph entropy. As a byproduct, our method also provides a conceptually simple proof of the known fact that computing a Boolean function may require as large rate as reproducing the entire source.
Autors: Shigeaki Kuzuoka;Shun Watanabe;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7003 - 7017
Publisher: IEEE
 
» On General Properties of Eigenvalues and Eigenfunctions of a Sturm–Liouville Operator: Comments on “ISS With Respect to Boundary Disturbances for 1-D Parabolic PDEs”
Abstract:
In the paper “ISS with respect to boundary disturbances for 1-D parabolic PDEs” (IEEE Transactions on Automatic Control, vol. 61, pp. 3712–3724, 2016), input-to-state stability properties are established for 1-D spatially varying parabolic partial differential equations (PDEs) under certain assumptions, imposed on eigenvalues and eigenfunctions of an associated Sturm–Liouville operator. A key assumption on the absolute convergence of an associated Fourier series, composed of the normalized eigenfunctions and inverse eigenvalues of the Sturm–Liouville operator, is analyzed in the present note. General properties of the Sturm–Liouville operator are carried out to demonstrate that such a key assumption becomes redundant for the underlying PDEs with sign-definite sufficiently smooth coefficients.
Autors: Yury Orlov;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5970 - 5973
Publisher: IEEE
 
» On Generalized Spatial Modulation Aided Millimeter Wave MIMO: Spectral Efficiency Analysis and Hybrid Precoder Design
Abstract:
The concept of generalized spatial modulation (GenSM) aided millimeter wave (mm-wave) multiple-input multiple-output (MIMO) has recently attracted substantial research interest, as it benefits from the large bandwidth of mm-wave MIMO, while maintaining a reduced number of radio frequency (RF) chains. However, due to the lack of precoding design, the preceding GenSM-aided mm-wave MIMO schemes suffered from severe performance loss. Inspired by the reduced-RF-chain structure making implementation cost low while maintaining the benefit of GenSM, in this paper, we incorporate the technique of hybrid precoding into GenSM-aided mm-wave MIMO, where a hybrid digital and analog precoding regime is proposed to enhance the system’s achievable rate. Moreover, a closed-form expression is proposed to provide an accurate approximation to the spectral efficiency (SE) achieved by the proposed scheme. The proposed expression is further simplified in the region of high signal-to-noise ratio (SNR). By exploiting the proposed SE expressions as low-complexity cost functions, two algorithms, i.e. the gradient ascent algorithm and the high-SNR approximation algorithm, are exploited to optimize the hybrid precoders in terms of SE maximization. Finally, numerical simulations are provided to substantiate the superior SE performance achieved by the proposed scheme over other GenSM-aided mm-wave MIMO schemes as well as the state-of-the-art mm-wave MIMO systems.
Autors: Longzhuang He;Jintao Wang;Jian Song;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7658 - 7671
Publisher: IEEE
 
» On Linear Precoding of Nonregenerative MIMO Relay Networks for Finite-Alphabet Source
Abstract:
Multiple input and multiple output (MIMO) relay could provide broader wireless coverage, better diversity, and higher throughput. Most existing precoder designs for either source or relay node are based on the assumption of Gaussian input signals. However, recent works have revealed possible performance loss of MIMO systems originally optimized for Gaussian source signals when applied to practical finite-alphabet source signals. In this work, we investigate the design problem of joint MIMO precoding for wireless two-hop nonregenerative cooperative relay networks under finite-alphabet source signals. We identify several structural properties of optimal precoders. Specifically, we provided the optimal left singular vectors of the relay precoder, and proved the convexity of mutual information with respect to the square of relay precoder singular value. These results generalize the two-hop relay networks in Gaussian input assumption to the cooperative relay networks in arbitrary finite-alphabet input signals. Furthermore, we propose gradient-based numerical iterative optimization algorithms not only for arbitrary finite-alphabet source signal precoding but also for cooperative relay networks which may or may not have a direct source to destination link. Our results demonstrate substantial performance improvement over existing precoder designed traditionally under Gaussian input assumption, which indicates that the waterfilling based precoding strategy is not suitable for finite-alphabet constellation source inputs.
Autors: Xiao Liang;Zhi Ding;Chengshan Xiao;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9761 - 9775
Publisher: IEEE
 
» On Methods to Determine Bounds on the $Q$ -Factor for a Given Directivity
Abstract:
This paper revisit and extend the interesting case of bounds on the -factor for a given directivity for a small antenna of arbitrary shape. A higher directivity in a small antenna is closely connected with a narrow impedance bandwidth. The relation between bandwidth and a desired directivity is still not fully understood, not even for small antennas. Initial investigations in this direction have related the radius of a circumscribing sphere to the directivity, and bounds on the -factor have also been derived for a partial directivity in a given direction. In this paper, we derive lower bounds on the -factor for a total desired directivity for an arbitrarily shaped antenna in a given direction as a convex problem using semidefinite relaxation (SDR) techniques. We also show that the relaxed solution is also a solution of the original problem of determining the lower -factor bound for a total desired directivity. SDR can also be used to relax a class of other interesting nonconvex constraints in antenna optimization, such as tuning, losses, and front-to-back ratio. We compare two different new methods to determine the lowest -factor for arbitrary-shaped antennas for a given total directivity. We also compare our results with full electromagnetic simulations of a parasitic element antenna with high directivity.
Autors: B.L.G. Jonsson;Shuai Shi;Lei Wang;Fabien Ferrero;Leonardo Lizzi;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 5686 - 5696
Publisher: IEEE
 
» On Minimal Steiner Maximum-Connected Subgraph Queries
Abstract:
Given a graph and a set of query nodes, we examine the Steiner Maximum-Connected Subgraph (SMCS) problem. The SMCS, or 's induced subgraph that contains with the largest connectivity, can be useful for customer prediction, product promotion, and team assembling. Despite its importance, the SMCS problem has only been recently studied. Existing solutions evaluate the maximum SMCS, whose number of nodes is the largest among all the SMCSs of . However, the maximum SMCS, which may contain a lot of nodes, can be difficult to interpret. In this paper, we investigate the minimal SMCS , which is the minimal subgraph of with the maximum connectivity containing . The minimal SMCS contains much fewer nodes than its maximum counterpart, and is thus easier to be understood. However, the minimal SMCS can be costly to evaluate. We thus propose effici- nt Expand-Refine algorithms, as well as their approximate versions with accuracy guarantees. We further develop a cache-based processing model to improve the efficiency for an important case when consists of a single node. Extensive experiments on large real and synthetic graph datasets validate the effectiveness and efficiency of our approaches.
Autors: Jiafeng Hu;Xiaowei Wu;Reynold Cheng;Siqiang Luo;Yixiang Fang;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Nov 2017, volume: 29, issue:11, pages: 2455 - 2469
Publisher: IEEE
 
» On Multi-Source Networks: Enumeration, Rate Region Computation, and Hierarchy
Abstract:
Recent algorithmic developments have enabled computers to automatically determine and prove the capacity regions of small hypergraph networks under network coding. A structural theory relating network coding problems of different sizes is developed to make the best use of this newfound computational capability. A formal notion of network minimality is developed, which removes components of a network coding problem that are inessential to its core complexity. Equivalence between different network coding problems under relabeling is formalized via group actions, an algorithm which can directly list single representatives from each equivalence class of minimal networks up to a prescribed network size is presented. This algorithm, together with rate region software, is leveraged to create a database containing the rate regions for all minimal network coding problems with five or fewer sources and edges, a collection of 744119 equivalence classes representing more than 9 million networks. In order to best learn from this database, and to leverage it to infer rate regions and their characteristics of networks at scale, a hierarchy between different network coding problems is created with a new theory of combinations and embedding operators.
Autors: Congduan Li;Steven Weber;John MacLaren Walsh;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7283 - 7303
Publisher: IEEE
 
» On Projected Stochastic Gradient Descent Algorithm with Weighted Averaging for Least Squares Regression
Abstract:
The problem of least squares regression of a -dimensional unknown parameter is considered. A stochastic gradient descent based algorithm with weighted iterate-averaging that uses a single pass over the data is studied and its convergence rate is analyzed. We first consider a bounded constraint set of the unknown parameter. Under some standard regularity assumptions, we provide an explicit upper bound on the convergence rate, depending on the variance (due to the additive noise in the measurements) and the size of the constraint set. We show that the variance term dominates the error and decreases with rate , while the term that is related to the size of the constraint set decreases with rate . We then compare the asymptotic ratio between the convergence rate of the proposed scheme and the empirical risk minimizer (ERM) as the number of iterations approaches infinity. We show that for all when the random entries of the sensing vector are uncorrelated and identically distributed. We further improve the upper bound by showing that for the case of and unbounded parameter set when the random sensing entries are equal across time. Simulation results demonstrate strong performance of the algorithm as compared to existing methods, and coincide with $rho leq 4/3$ even for large in practice.
Autors: Kobi Cohen;Angelia Nedić;R. Srikant;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5974 - 5981
Publisher: IEEE
 
» On Ransomware and Envisioning the Enemy of Tomorrow
Abstract:
We warned the public more than 20 years ago that cryptoviral extortion would pose a major threat to users, a threat that has been realized with the advent of Bitcoin but largely neglected until recently. We believe that a reactive mindset along with group conformity are partly to blame for this oversight and, moreover, are negatively impacting secure systems research. This presents a recipe for disaster, for while cryptoviral extortion is wreaking havoc on the surface, covert cryptovirology attacks are likely gathering strength within the shadows.
Autors: Adam L. Young;Moti Yung;
Appeared in: Computer
Publication date: Nov 2017, volume: 50, issue:11, pages: 82 - 85
Publisher: IEEE
 
» On the Correlation Distribution for a Niho Decimation
Abstract:
Let be a prime, and with , and . In this paper, the correlation distribution between a -ary -sequence of period and its -decimation sequence is investigated in a unified approach. Some results for the binary case are extended to the general case. It is shown that the problem of determining the correlation distribution for can be reduced to that of solving two combinatorial problems related to the unit circle of the finite field . For an arbitrary odd prime , it seems difficult to solve these two problems. However, for , by studying the weight distribution of the ternary Zetterberg code and counting the numbers of solutions of some equations over , the two problems are solved, and thus, the corresponding correlation distribution for is completely determined. It is - oteworthy that this is the first time that the correlation distribution for a non-binary Niho decimation has been determined since 1976.
Autors: Yongbo Xia;Nian Li;Xiangyong Zeng;Tor Helleseth;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7206 - 7218
Publisher: IEEE
 
» On the Covariance Matrix and Diversity Performance Evaluation of Compact Multiport Antenna Systems
Abstract:
In this communication, we present a new electromagnetic methodology that determines the covariance matrix of compact multiport antenna (MPA) systems at the early design stage. Further insight into this field is provided, as contrary to existing methodologies, it rigorously relies on the reciprocity principle of MPA systems. Thus, the impact of propagation environment, termination conditions, and MPA radiation characteristics as independent factors affecting performance is physically incorporated. Provided the availability of mathematical expressions for the cumulative distribution function and probability density function of received signal-to-noise ratio (SNR), performance can then be analytically studied via the diversity antenna gain (DAG) in terms of: 1) SNR enhancement at a specific outage probability (OP) level (that is DAG-OP) and 2) average SNR reduction for achieving a specific average bit error rate (BER) (that is DAG-BER). Illustrative examples with performance evaluation of compact MPA systems are presented. The adopted diversity technique is the transmit antenna selection/maximal ratio combining, which is analytically studied employing realistic MPA systems for the first time. Comparisons with existing published results further demonstrate the validity and usefulness of the proposed methodology.
Autors: Vasilis Papamichael;Petros Karadimas;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6140 - 6144
Publisher: IEEE
 
» On the Decidability and Complexity of Diagnosability for Labeled Petri Nets
Abstract:
In this paper, we investigate the decidability and complexity of the fault diagnosis problem in unbounded labeled Petri nets. First, we show that checking diagnosability for unbounded Petri nets is decidable. We present a new necessary and sufficient condition for diagnosability, which can be reduced to a model checking problem for unbounded Petri nets. Then, we show that checking diagnosability for unbounded Petri nets is EXPSPACE-complete. This complexity result is further extended to various subclasses of Petri nets. To the best of our knowledge, this is the first paper that establishes decidability and complexity results for diagnosability of unbounded Petri nets.
Autors: Xiang Yin;Stéphane Lafortune;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5931 - 5938
Publisher: IEEE
 
» On the Design and Construction Assessments of a Permanent-Magnet-Assisted Synchronous Reluctance Motor
Abstract:
By appropriately inserting ferrite magnets into the rotor of a synchronous reluctance motor (SynRM), the machine operational power factors and torque outputs can be improved. With specific rotor structures to accommodate those ferrites, many of these permanent-magnet-assisted SynRMs (PMA-SynRMs) have been proposed to comply the expected operational objectives. For construction convenience, the ferrites that being inserted into the flux barriers of these PMA-SynRMs are generally in rectangular shapes; hence, some adjustments on the rotor flux barriers and additional bridges are required. Such changes will inevitably affect the performance of the original SynRMs with optimized rotor structures, and these tradeoffs are thus to be recovered by parts of those adopted ferrites. This paper will provide an evaluation index that can characterize the performance of PMA-SynRMs with different volume compositions of the ferrites, along with the impact assessments of the SynRMs with modified flux barriers such that those ferrites can be properly allocated. Based on the designs obtained from thorough 3-D finite-element analyses, a 3-hp PMA-SynRM will be constructed and the related experimental measurements will also be supported to validate the design adequacies.
Autors: Cheng-Tsung Liu;Ta-Yin Luo;Pei-Chun Shih;Sheng-Chan Yen;Hsin-Nan Lin;Yu-Wei Hsu;Chang-Chou Hwang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» On the Design of Maximal-Rate Shape-Preserving $2times 2$ and $3times 3$ Space-Time Codes for Noncoherent Energy-Detection-Based PPM Communications
Abstract:
In this paper, we propose novel and noncoherent space-time (ST) codes for impulse-radio ultra-wideband communications with pulse position modulation (PPM). The code design is based on existing coherent ST codes, where the associated constellation is confined in order to achieve full diversity with analog energy detectors. A comprehensive performance analysis guides this confinement and highlights the maximum rates that can be achieved by this specific layered code word structure with two and three transmit antennas. The proposed codes attain these maximum rates without introducing any expansion to the unipolar PPM signal set.
Autors: Chadi Abou-Rjeily;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7432 - 7445
Publisher: IEEE
 
» On the Effect of Spatially Non-Disjoint Training and Test Samples on Estimated Model Generalization Capabilities in Supervised Classification With Spatial Features
Abstract:
In this letter, we establish two sampling schemes to select training and test sets for supervised classification. We do this in order to investigate whether estimated generalization capabilities of learned models can be positively biased from the use of spatial features. Numerous spatial features impose homogeneity constraints on the image data, whereby a spatially connected set of image elements is attributed identical feature values. In addition to a frequent occurrence of intrinsic spatial autocorrelation, this leads to extrinsic spatial autocorrelation with respect to the image data. The first sampling scheme follows a spatially random partitioning into training and test sets. In contrast to that, the second strategy implements a spatially disjoint partitioning, which considers in particular topological constraints that arise from the deployment of spatial features. Experimental results are obtained from multi- and hyperspectral acquisitions over urban environments. They underline that a large share of the differences between estimated generalization capabilities obtained with the spatially disjoint and non-disjoint sampling strategies can be attributed to the use of spatial features, whereby differences increase with an increasing size of the spatial neighborhood considered for computing a spatial feature. This stresses the necessity of a proper spatial sampling scheme for model evaluation to avoid overoptimistic model assessments.
Autors: Christian Geiß;Patrick Aravena Pelizari;Henrik Schrade;Alexander Brenning;Hannes Taubenböck;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2008 - 2012
Publisher: IEEE
 
» On the Energy and Spectral Efficiency Tradeoff in Massive MIMO-Enabled HetNets With Capacity-Constrained Backhaul Links
Abstract:
In this paper, we propose a general framework to study the tradeoff between energy efficiency (EE) and spectral efficiency (SE) in massive multiple-input-multiple-output-enabled heterogenous networks while ensuring proportional rate fairness among users and taking into account the backhaul capacity constraint. We aim at jointly optimizing user association, spectrum allocation, power coordination, and the number of activated antennas, which is formulated as a multi-objective optimization problem maximizing EE and SE simultaneously. With the help of weighted Tchebycheff method, it is then transformed into a single-objective optimization problem, which is a mixed-integer non-convex problem and requires unaffordable computational complexity to find the optimum. Hence, a low-complexity effective algorithm is developed based on primal decomposition, where we solve the power coordination and number of antenna optimization problem and the user association and spectrum allocation problem separately. Both theoretical analysis and numerical results demonstrate that our proposed algorithm can fast converge within several iterations and significantly improve both the EE-SE tradeoff performance and rate fairness among users compared with other algorithms.
Autors: Yuanyuan Hao;Qiang Ni;Hai Li;Shujuan Hou;
Appeared in: IEEE Transactions on Communications
Publication date: Nov 2017, volume: 65, issue:11, pages: 4720 - 4733
Publisher: IEEE
 
» On the Evaluation of Different High-Performance Computing Platforms for Hyperspectral Imaging: An OpenCL-Based Approach
Abstract:
Hyperspectral imaging systems are a powerful tool for obtaining surface information in many different spectral channels that can be used in many different applications. Nevertheless, the huge amount of information provided by hyperspectral images also has a downside, since it has to be processed and analyzed. For such purpose, parallel hardware devices, such as field-programmable gate arrays (FPGAs) and graphic processing units (GPUs), are typically used, especially for hyperspectral imaging applications under real-time constraints. However, developing hardware applications typically requires expertise in the specific targeted device, as well as in the tools and methodologies that can be used to perform the implementation of the desired algorithms in that device. In this scenario, the Open Computing Language (OpenCL) emerges as a very interesting solution in which a single high-level language can be used to efficiently develop applications in multiple and different hardware devices. In this work, the parallel Fast Algorithm for Linearly Unmixing Hyperspectral Images (pFUN) has been implemented in two different NVIDIA GPUs, the GeForce GTX 980 and the Tesla K40c, using OpenCL. The obtained results are compared with the results provided by the previously developed NVIDIA CUDA implementation of the pFUN algorithm for the same GPU devices for comparing the efficiency of OpenCL against a more specific synthesis design language for the targeted hardware devices, such as CUDA is for NVIDIA GPUs. Moreover, the FUN algorithm has also been implemented into a Bitware Stratix V Altera FPGA, using OpenCL, for comparing the results that can be obtained using OpenCL when targeting different devices and architectures. The obtained results demonstrate the suitability of the followed methodology in the sense that it allows the achievement of efficient FPGA and GPU implementations able to cope with the stringent requirements imposed by hyperspectral imaging systems.
Autors: Raúl Guerra;Ernestina Martel;Jehandad Khan;Sebastián López;Peter Athanas;Roberto Sarmiento;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 4879 - 4897
Publisher: IEEE
 
» On the Exact and Approximate Eigenvalue Distribution for Sum of Wishart Matrices
Abstract:
The sum of Wishart matrices has an important role in multiple-input multiple-output (MIMO) multiple access channel (MAC) and MIMO relay channel. In this paper, we present a new closed-form expression for the marginal density of one of the unordered eigenvalues of a sum of complex central Wishart matrices having covariance matrices proportional to the identity matrix. The expression is general and allows for any set of linear coefficients. The derived expression is used to obtain the ergodic sum-rate capacity for the MIMO-MAC and MIMO relay cases, both as closed-form expressions. We also present a very simple expression to approximate the sum of Wishart matrices by one equivalent Wishart matrix. The agreement between the exact eigenvalue distribution and numerical simulations is perfect, whereas for the approximate solution the difference is indistinguishable.
Autors: Gabriel Fernando Pivaro;Santosh Kumar;Gustavo Fraidenraich;Claudio Ferreira Dias;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10537 - 10541
Publisher: IEEE
 

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