Electrical and Electronics Engineering publications abstract of: 11-2017 sorted by title, page: 9

» GPU-Based Batch LU-Factorization Solver for Concurrent Analysis of Massive Power Flows
Abstract:
In many power system applications, such as N–x static security analysis and Monte-Carlo-simulation-based probabilistic power flow (PF) analysis, it is a very time-consuming task to analyze massive number of PFs on identical or similar network topology. This letter presents a novel GPU-accelerated batch LU-factorization solver that achieves higher level of parallelism and better memory-access efficiency through packaging massive number of LU-factorization tasks to formulate a new larger-scale problem. The proposed solver can achieve up to 76 times speedup when compared to KLU library and lays a critical foundation for massive-PFs-solving applications.
Autors: Gan Zhou;Rui Bo;Lungsheng Chien;Xu Zhang;Fei Shi;Chunlei Xu;Yanjun Feng;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4975 - 4977
Publisher: IEEE
 
» Graph Theoretic Approach to the Robustness of $k$ -Nearest Neighbor Vehicle Platoons
Abstract:
We consider a graph-theoretic approach to the performance and robustness of a platoon of vehicles, in which each vehicle communicates with its -nearest neighbors. In particular, we quantify the platoon’s stability margin, robustness to disturbances (in terms of system norm), and maximum delay tolerance via graph-theoretic notions, such as nodal degrees and (grounded) Laplacian matrix eigenvalues. The results show that there is a trade-off between robustness to time delay and robustness to disturbances. Both first-order dynamics (reference velocity tracking) and second-order dynamics (controlling inter-vehicular distance) are analyzed in this direction. Theoretical contributions are confirmed via simulation results.
Autors: Mohammad Pirani;Ehsan Hashemi;John W. Simpson-Porco;Baris Fidan;Amir Khajepour;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Nov 2017, volume: 18, issue:11, pages: 3218 - 3224
Publisher: IEEE
 
» Graphene Effect on the Improvement of the Response of Optical Fiber SPR Sensor
Abstract:
In this paper, we present a contribution to the development of a fiber-optic surface plasmon resonance sensor coated with a silver film that is suitable for chemical and biological applications. Indeed, the importance of the choice of the metal deposited on the sensitive zone of the sensor was verified. It has been found that silver-based sensors have better sensitivity. But on the other hand, it suffers from its poor chemical stability. In order to improve sensor stability, a protective layer of graphene was added, and an optimization of the geometrical and physical properties characteristic of the new configuration was presented by using a numerical study. The results obtained show that the sensitivity of the sensor depends on a set of parameters, such as the diameter of the core (), the sensitive length (), and the thickness of the metal layer () and its nature. The optimal choice of these parameters was fixed for the following values: , mm, and nm.
Autors: Yosra Saad;Marwa Selmi;Mohamed Hichem Gazzah;Hafedh Belmabrouk;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7440 - 7447
Publisher: IEEE
 
» Graphene Sensing Modulator: Toward Low-Noise, Self-Powered Wireless Microsensors
Abstract:
We present here new types of self-powered, low-interference wireless sensors based on graphene circuits, which can have dual functions: chemical sensing at the molecular level and radio-frequency (RF) modulation. We demonstrate that a fully passive, graphene-based harmonic (transponder) sensor can display a chemically sensitive frequency multiplication effect, which, when linked to a hybrid-fed small antenna, can realize an ultrasensitive, low-profile, light-weight, and potentially flexible RF sensor. We have designed two different types of circuits comprising back-gate graphene field-effect transistors (GFETs) and compared in detail their performance and implementation complexity. We have also proposed a reliable readout method based on the machine learning for extracting the mean value and the fluctuation of chemical doping levels in GFETs. The proposed graphene-based harmonic sensor may potentially benefit a wide range of sensing applications, including, but not limited to, power-efficient, real-time monitoring of chemical/gas exposures and biological agents, as well as emerging wearable and implantable devices.
Autors: Mehdi Hajizadegan;Maryam Sakhdari;Liang Zhu;Qingsong Cui;Haiyu Huang;Mark M. C. Cheng;Jonathan C. H. Hung;Pai-Yen Chen;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7239 - 7247
Publisher: IEEE
 
» Graphene-Assisted Polarization-Insensitive Electro-absorption Optical Modulator
Abstract:
We report on a polarization-insensitive optical modulator architecture comprised of silica/Si/hBN/graphene/hBN/graphene/hBN/Si stack upon a silica substrate to support transverse electric (TE) and transverse magnetic (TM) polarizing modes with identical absorption. The identical absorption between TE and TM modes is strict condition for realizing polarization-insensitive electro-absorption optical modulator. This in turn entails significant compromise in polarization-sensitivity loss. The horizontal arm of active region of waveguide support TE mode while TM mode is supported by vertical arm ensuring polarization-sensitive loss of < 1 dB. The model is capable of offering extinction ratio of 18.87 dB, insertion loss of 2.32 dB and figure-of-merit of 8.14 for TE mode. Concurrently, for TM mode are 19.39 dB, 2.41 dB and 8.04. The operating wavelength of modulator ranges from ∼ 1500 to ∼ 1590 nm with optical bandwidth excess of 90 nm. The 3-dB modulation bandwidth of 62.74 GHz is realized with active length of 12 μm long at the expense of 1.28 fJ/bit ensuring the polarization-sensitive loss at ON-State of 0.1 dB and tolerance between TE and TM modes of 0.82 dB.
Autors: Manoj Kumar Shah;Rongguo Lu;Di Peng;Yangxue Ma;Shengwei Ye;Yali Zhang;Zhiyao Zhang;Yong Liu;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 1004 - 1010
Publisher: IEEE
 
» Greene Approximation Wide-Angle Parabolic Equation for Radio Propagation
Abstract:
This paper presents the Greene second-order parabolic equation (PE) solution to model radio propagation over irregular terrain. This solution is implemented by finite-difference and shift-map technique. The second-order finite-difference approach performs well for slopes up to about 15°, and discontinuous slope changes up to about 30°, which is better than can be achieved using the split-step/Fourier approach. The results prove that the Greene PE solution has greater propagation angles than does the Claerbout PE solution. Thus, the Greene second-order solution can certainly give better results for large angle propagation over complicated terrain boundaries. Besides, we treat the important problem of accuracy of the different approximations of the PE-based propagation models, and derive the general PE solutions with respect to the terrain slope for the different approximations. It is useful to have collected in one paper, the most important PE approximations for radio propagation.
Autors: Qi Guo;Ci Zhou;Yunliang Long;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6048 - 6056
Publisher: IEEE
 
» Group Testing Schemes From Codes and Designs
Abstract:
In group testing, simple binary-output tests are designed to identify a small number of defective items that are present in a large population of items. Each test takes as input a group of items and produces a binary output indicating whether the group is free of the defective items or contains one or more of them. In this paper, we study a relaxation of the combinatorial group testing problem. A matrix is called -disjunct if it gives rise to a nonadaptive group testing scheme with the property of identifying a uniformly random -set of defective subjects out of a population of size with false positive probability of an item at most . We establish a new connection between -disjunct matrices and error correcting codes based on the dual distance of the codes and derive estimates of the parameters of codes that give rise to such schemes. Our methods rely on the moments of the distance distribution of codes and inequalities for moments of sums of independent random variables. We also provide a new connection between group testing schemes and combinatorial designs.
Autors: Alexander Barg;Arya Mazumdar;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7131 - 7141
Publisher: IEEE
 
» Group-Based Behavior Adaptation Mechanisms in Object-Oriented Systems
Abstract:
Dynamic and distributed systems require behavior adaptations for groups of objects. Group-based behavior adaptation mechanisms scope adaptations to objects matching certain conditions. The specification of groups can be implicit or explicit.
Autors: Patrick Rein;Stefan Ramson;Jens Lincke;Tim Felgentreff;Robert Hirschfeld;
Appeared in: IEEE Software
Publication date: Nov 2017, volume: 34, issue:6, pages: 78 - 82
Publisher: IEEE
 
» Guest Editorial
Abstract:
The increasing data transmit rates per user (download speeds of about 1 Gb/s in 4G and 20 Gb/s in 5G), paired with the increasing number of users (people or devices) in mobile communications, require the continuous extension of the wireless network capacity. The demand for additional and higher usage of the available frequency spectrum is the driving force for the frequency spectrum adaptation at microwaves and millimeter waves and the implementation of new 3GPP cellular standards. These standards include multiband operation, carrier aggregation, and multi-input multi-output air interfaces.
Autors: Andreas Tag;Amelie Hagelauer;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Nov 2017, volume: 65, issue:11, pages: 4529 - 4530
Publisher: IEEE
 
» Guest Editorial Special Issue on Selected Papers From the IEEE SENSORS 2016 Conference
Abstract:
Over the years, the IEEE SENSORS Conference has become one of the premier, truly global event on novelties in any discipline related to sensors and addressing the whole range from principles, design and fabrication to interfacing, data-extraction, applications, and systems. The most recent conference of this series, the IEEE SENSORS 2016 Conference was held October 30 – November 2, 2016, in Orlando, Florida, USA. In a major departure from previous years, IEEE SENSORS 2016 solicited peer-reviewed 3-page conference papers for the first time, which was received with great enthusiasm by our community. A total of 1049 submissions were received, close to the largest in the SENSORS conference history, of which 617 were accepted (58.82%). Track Chairs handled the review process. All accepted papers went through the same peer-review process, each receiving 5 reviews, and those accepted were published in the conference proceedings in IEEE Xplore. However, they were divided into oral (198) and poster (420) presentations at the SENSORS conference depending upon author preference, suitability, session planning and similar considerations. Authors of 31 conference papers identified for the Best Paper Award from the 16 applicable Tracks were invited to submit expanded versions of their conference papers to this “Selected Papers from the IEEE SENSORS 2016 Conference” Special Issue of the IEEE Sensors Journal, of whom 18 submitted. After rigorous peer review according to the editorial procedures of the Journal, the Guest Editors of this Special Issue accepted 12 for publication and included them in the collection on the following pages.
Autors: Venkat R. Bhethanabotla;Fabien J. Josse;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7222 - 7222
Publisher: IEEE
 
» Guest Editorial Special Section on the 2016 International Symposium on Semiconductor Manufacturing
Abstract:
Since its start in 1992 in Japan, the International Symposium on Semiconductor Manufacturing (ISSM) has provided unique opportunities to share the best practices of semiconductor manufacturing technologies for professionals worldwide. At the symposium, professionals assemble to discuss the technologies developed to meet worldwide requirements for advanced semiconductor manufacturing. It is crucial to re-examine semiconductor manufacturing in terms of fundamental principles to improve the performance of devices. In addition, manufacturing technologies that preserve the Earth’s environment will require new concepts and stronger collaborative efforts to find precompetitive solutions to the challenges posed.
Autors: Toshiharu Katayama;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 315 - 316
Publisher: IEEE
 
» Guest Editorial Special Section on the 2016 SEMI Advanced Semiconductor Manufacturing Conference
Abstract:
The past year has brought many reminders that we live in an increasingly digital world. Technology shapes and enhances our lives each day on several fronts.

Shopping from the comfort of our homes.

Ready access to a multitude of information using our smartphones or other kinds of wireless devices, often accessed with the help of voice technology and digital assistants.

Smart control of our homes and offices, saving power, improving comfort, and enhancing our security.

Active driver assistance and accident avoidance features now commonplace in today’s cars.

Development of new, useful, technologies and services such as cyber currency, easy point-of-sale transactions, and the self-service kiosks we use at the supermarket and airport.

And there are trends that many of us consider troubling.

Worrisome levels of telephone attachment in today’s teens.

Election hacking and manipulative social media engineering.

Cyber crime such as the WannaCry virus.

Stolen identities.

Autors: Oliver D. Patterson;Paul Werbaneth;Jeanne Paulette Bickford;Stefan Radloff;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 377 - 379
Publisher: IEEE
 
» Hadamard-Encoded Multipulses for Contrast-Enhanced Ultrasound Imaging
Abstract:
The development of contrast-enhanced ultrasound (CEUS) imaging offers great opportunities for new ultrasound clinical applications such as myocardial perfusion imaging and abdominal lesion characterization. In CEUS imaging, the contrast agents (i.e., microbubbles) are utilized to improve the contrast between blood and tissue based on their high nonlinearity under low ultrasound pressure. In this paper, we propose a new CEUS pulse sequence by combining Hadamard-encoded multipulses (HEM) with fundamental frequency bandpass filter (i.e., filter centered on transmit frequency). HEM consecutively emits multipulses encoded by a second-order Hadamard matrix in each of the two transmission events (i.e., pulse-echo events), as opposed to conventional CEUS methods which emit individual pulses in two separate transmission events (i.e., pulse inversion (PI), amplitude modulation (AM), and PIAM). In HEM imaging, the microbubble responses can be improved by the longer transmit pulse, and the tissue harmonics can be suppressed by the fundamental frequency filter, leading to significantly improved contrast-to-tissue ratio (CTR) and signal-to-noise ratio (SNR). In addition, the fast polarity change between consecutive coded pulse emissions excites strong nonlinear microbubble echoes, further enhancing the CEUS image quality. The spatial resolution of HEM image is compromised as compared to other microbubble imaging methods due to the longer transmit pulses and the lower imaging frequency (i.e., fundamental frequency). However, the resolution loss was shown to be negligible and could be offset by the significantly enhanced CTR, SNR, and penetration depth. These properties of HEM can potentially facilitate robust CEUS imaging for many clinical applications, especially for deep abdominal organs and heart.
Autors: Ping Gong;Pengfei Song;Shigao Chen;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Nov 2017, volume: 64, issue:11, pages: 1674 - 1683
Publisher: IEEE
 
» Handling Physical-Layer Deadlock Caused by Permanent Faults in Quasi-Delay-Insensitive Networks-on-Chip
Abstract:
Networks-on-Chip (NoCs) are promising fabrics to provide scalable and efficient on-chip communication for large-scale many-core systems. In place of the well-studied synchronous NoCs, the event-driven asynchronous ones have emerged as promising replacement thanks to their strong timing robustness especially when implemented in quasi-delay-insensitive (QDI) circuits. However, their fault tolerance has rarely been studied. The QDI NoCs show complicated failure scenarios and behave differently from synchronous ones. As the scaling semiconductor technology is expected with the accelerated aging process, permanent faults become more likely to happen at runtime. These faults can break the handshake, leading to physical-layer deadlocks which can spread and paralyze the whole QDI NoC. This physical-layer deadlock cannot be resolved using conventional fault-tolerant or deadlock management techniques. This paper systematically studies the impact of permanent faults on QDI NoCs, and presents novel deadlock detection and recovery techniques to handle the fault-caused physical-layer deadlock. The proposed detection technique has been implemented to protect the NoC data paths that occupy ~90% of the logic. Employing the detection and recovery techniques to protect interrouter links (~60% of the logic), a permanently faulty link is precisely located and the network function can be recovered with graceful performance degradation.
Autors: Guangda Zhang;Wei Song;Jim Garside;Javier Navaridas;Zhiying Wang;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Nov 2017, volume: 25, issue:11, pages: 3152 - 3165
Publisher: IEEE
 
» Harnessing Technology for Humanity [Pathways]
Abstract:
How can we harness the technologies of electronics, signal processing, and vision systems for the benefit of humanity? Discusses the work of Mohit Setia, an electrical engineer from San Diego, CA. It is Setia's goal to harness the technologies of electronics, signal processing, and vision systems to develop new medical services that will benefit mankind in remote areas and developing countries.
Autors: David Eng;
Appeared in: IEEE Industry Applications Magazine
Publication date: Nov 2017, volume: 23, issue:6, pages: 80 - 81
Publisher: IEEE
 
» Healthy Routes in the Smart City: A Context-Aware Mobile Recommender
Abstract:
Smart cities have sensors and communication infrastructures that provide humongous amounts of data. People can extend this infrastructure, acting as independent, mobile sensors through their smartphones, enabling opportunistic sensing. This information provides locality and timeliness of measurements that would otherwise be unavailable. Researchers have developed a context-aware healthy-route recommender system that offers personalized recommendations to people according to their medical condition and real-time information from the smart city. Experiments with a simulated dataset and real data verified the system’s usefulness.
Autors: Fran Casino;Constantinos Patsakis;Edgar Batista;Frederic Borràs;Antoni Martínez-Ballesté;
Appeared in: IEEE Software
Publication date: Nov 2017, volume: 34, issue:6, pages: 42 - 47
Publisher: IEEE
 
» Heat and Mass Transfer of a Casson Nanofluid Flow Over a Porous Surface With Dissipation, Radiation, and Chemical Reaction
Abstract:
Casson nanofluid flow with dissipation, radiation, and chemical reaction in the presence of a temperature gradient dependent heat sink subject to suction is analyzed. Hence, this paper mainly deals nanofluids with nanoparticles Cu, Au, Ag, Al, Al2O3, and TiO2 and with base fluid water. Prescribed surface temperature and concentration boundary conditions are employed on the porous surface. Suitable similarity transformations are introduced for converting nonlinear partial differential equations into the nonlinear ordinary differential equations and then solved by analytically. The influence of various physical parameters such as the nanoparticle volume fraction, Casson fluid parameter, suction parameter, permeability parameter, heat sink parameter, Prandtl number, Eckert number, radiation parameter, Schmidt number, and chemical reaction parameter over the velocity, temperature, and species concentration of nanofluid Cu-water is examined by using graphs. Skin friction coefficient, Nusselt number, and Sherwood number of various nanofluids with nanoparticles (Cu, Ag, Au, Al, Al2O3, and TiO2) are tabulated and analyzed.
Autors: Senniappan Palaniammal;Kandhasamy Saritha;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 909 - 918
Publisher: IEEE
 
» Heat Exchangers From Metal-Bonded La(Fe,Mn,Si)13Hx Powder
Abstract:
Hydrogenated La(Fe,Mn,Si)13-based alloys have an excellent magnetocaloric properties, but poor mechanical and chemical stability. This hinders their direct machining and implementation in an active magnetic regenerator (AMR). In this paper, we show how machinability and corrosion protection of the particles can be improved by a hot-dip coating. To avoid the loss of hydrogen during the coating process, a low melting temperature eutectic Bi–Sn–In alloy was selected as a metal binder. The coated particles were used to build a packed bed regenerator as an array of fixed particles, avoiding such negative effects as sedimentation, segregation, and channel deformation. Similarity theory, combined with unsteady heat transfer approach was applied in order to calculate the optimal operation frequency and to estimate the maximal cooling power of the magnetocaloric regenerators. Two different geometries of heat exchangers were theoretically compared: stacked flat plate/channel structure and packed bed of equidimensional spherical particles. It is shown that, operating at low frequency, the same amount of magnetocaloric material can expel bigger amount of heat, when formed as packed bed heat exchangers. The metal-bonded packed bed regenerator made from La(Fe,Mn,Si)13Hx powder was tested in a home-build versatile testing device in a magnetic field change of 10 kOe. The maximal achievable temperature span as a function of both parameters—hot end temperature and length of regenerator—was explored. The largest thermal span of 8 K was produced by the regenerator with 40 mm length.
Autors: Iliya A. Radulov;Dmitriy Yu Karpenkov;Marius Specht;Tobias Braun;Alexey Yu Karpenkov;Konstantin P. Skokov;Oliver Gutfleisch;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 7
Publisher: IEEE
 
» Heat-Assisted Recording: Advances in Recording Integration
Abstract:
Differences between heat-assisted magnetic recording (HAMR) and conventional perpendicular magnetic recording (PMR) for signal processing of the written track by one and two reader multisensor magnetic recording (MSMR) are explored using spinstand measurements. Tracks written with HAMR heads are shown to have more curvature compared with those written with modern PMR writers. We introduce two signal processing techniques in order to determine the merits and explore the recording physics tradeoffs for this complex system. To first order, we see twice as much bit error rate (BER) gain for the HAMR written track—on readback—using two reader MSMR, than the PMR. This difference we assign to the lower electronic signal-to-noise (SNR) ratio for the HAMR written track. In order to replicate practical conditions, we stress the MSMR system by applying increased adjacent track squeeze and displacing the two readers from the center of the track. Under these conditions we can resolve differences between the PMR and HAMR systems. Increased adjacent track squeeze appears to trim the broad and curved track edges, until the on-track signal starts to degrade. Increased offset of the readers from the center of the track offers improved the media (spatial) SNR, but we fail to harvest all those gains into BER across the range. We hypothesize that this is due to increasing distortion, a combination of track edge noise and reading of the encroaching tracks.
Autors: Chris Rea;Pavol Krivosik;Veerakumar Venugopal;M. Fatih Erden;Scott Stokes;Pradeep Subedi;Michael Cordle;Mourad Benakli;Hua Zhou;Darren Karns;Douglas Saunders;Scott Franzen;Ganping Ju;Tim Rausch;Mike Seigler;Edward Gage;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» Heating Effects of Colloidal ZnO Quantum Dots (QDs) on ZnO QD/CdSe QD/MoOx Photodetectors
Abstract:
In this article, the effects of heat treatment of colloidal ZnO quantum dots (QDs, diameter ∼1.83 nm - 2.43 nm) based electron transport layer (ETL) on the performance of ZnO QDs/CdSe QDs/MoO$_x$/Ag photodetectors (PDs) have been investigated possibly for the first time. The Colloidal CdSe QDs (diameter ∼4.84 - 5.85 nm) and MoO$_x$ are used as the active layer and hole transport layer (HTL) in the PDs, respectively. The photoresponse and response time measured for 250°C, 350°C, and 450°C annealing temperatures of the ETL have been compared. The PDs shows the best performance for the annealing temperature of 250°C. The average response time, dark current and contrast ratio (i.e., ratio of photocurrent to dark current) of the PDs are measured as 25.5 ms, -0.02 μA and 1216 for 250°C, 31.7 ms, -0.06 μA and 170.8 for 350°C and 56.31 ms, -0.37 μA and 7 for 450°C respectively. The responsivity, detectivity, and external quantum efficiency (EQE) at a wavelength of 386 nm for an applied bias of -0.1 V are measured as 32.4 mA/W, 1.22×10$^{12}$ cmHz$^{1/2}$W$^{-1}$ and 10.88% for 250°C, 11.2 mA/W, 5.64×10$^{11}$ cmHz$^{1/2}$W$^{-1}$ and 3.62% for 350°C and 2.2 mA/W, 4.69×10$^{9}$ cmHz$^{1/2}$W$^{-1}$ and 0.706% for 450°C respectively. Thus, the performance of the PDs gets deteriorated at higher annealing temperatures- of the ZnO QDs based ETL of the device under consideration.
Autors: Hemant Kumar;Yogesh Kumar;Gopal Rawat;Chandan Kumar;Bratindranath Mukherjee;Bhola Nath Pal;Satyabrata Jit;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 1073 - 1080
Publisher: IEEE
 
» Hermes: Latency Optimal Task Assignment for Resource-constrained Mobile Computing
Abstract:
With mobile devices increasingly able to connect to cloud servers from anywhere, resource-constrained devices can potentially perform offloading of computational tasks to either save local resource usage or improve performance. It is of interest to find optimal assignments of tasks to local and remote devices that can take into account the application-specific profile, availability of computational resources, and link connectivity, and find a balance between energy consumption costs of mobile devices and latency for delay-sensitive applications. We formulate an NP-hard problem to minimize the application latency while meeting prescribed resource utilization constraints. Different from most of existing works that either rely on the integer programming solver, or on heuristics that offer no theoretical performance guarantees, we propose Hermes, a novel fully polynomial time approximation scheme (FPTAS). We identify for a subset of problem instances, where the application task graphs can be described as serial trees, Hermes provides a solution with latency no more than times of the minimum while incurring complexity that is polynomial in problem size and . We further propose an online algorithm to learn the unknown dynamic environment and guarantee that the performance gap compared to the optimal strategy is bounded by a logarithmic function with time. Evaluation is done by using real data set collected from several benchmarks, and is shown that Hermes improves the latency by p- rcent compared to a previously published heuristic and increases CPU computing time by only percent of overall latency.
Autors: Yi-Hsuan Kao;Bhaskar Krishnamachari;Moo-Ryong Ra;Fan Bai;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Nov 2017, volume: 16, issue:11, pages: 3056 - 3069
Publisher: IEEE
 
» Heterogeneous Integrated Wireless Displacement Sensor
Abstract:
In this paper, a new design of a heterogeneous integrated wireless sensor for displacement measurement is presented. The designed sensor consists of an inductor fabricated in printed circuit board technology, as an essential part, a spacer, and an electrode on a flexible polyimide foil as membrane. The proposed design of a sensor enables wireless displacement measurements using an external inductor as an antenna. Deflecting the polyimide membrane draws the electrode close to the coil of inductor (as bottom electrode) and causes an increase in the capacitance between them which changes the resonant frequency of the sensor. Displacement is wirelessly measured by phase-dip method determining the change of the resonant frequency of the antenna sensor system. The measurement of the sensor is performed and the characteristic of the sensor is obtained. Displacement is measured up to 500 in the steps of 50 , and the resulting sensitivity of designed sensor is 16.2 kHz/.
Autors: Milica G. Kisic;Nelu V. Blaz;Ljiljana D. Zivanov;Mirjana S. Damnjanovic;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Heterogeneous Integration of Microwave GaN Power Amplifiers With Si Matching Circuits
Abstract:
GaN high electron mobility transistors were integrated into monolithic microwave integrated circuits (MMICs) by molding hetero-substrates and using a redistribution layer (RDL). Driver amplifiers (DAs) and high-power amplifiers (HPAs) on SiC substrates were molded with matching circuits on Si substrates including Cu-filled through-substrate vias (TSVs), and their circuits on hetero-substrates were connected using a Cu RDL. This was the first attempt to fabricate hetero-substrate MMICs with five chips for two-stage power amplifiers. This method will be very useful to increase the achievable quantity of small DAs and HPAs—as opposed to using large MMICs with matching circuits on a SiC substrate—and to reduce production costs. Furthermore, various frequency bands, such as the millimeter-wave band, can be accommodated by changing the Si chips of the matching circuits.
Autors: Motonobu Sato;Yasushi Kobayashi;Yoshitaka Niida;Kenji Saito;Naoko Kurahashi;Ayumi Okano;Yukio Ito;Teruo Kurahashi;Shinya Iijima;Yoshihiro Nakata;Masaru Sato;Naoya Okamoto;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 450 - 455
Publisher: IEEE
 
» Hexagonal Closed Packed CoPtRu Alloy as a Buffer Layer Material for Promoting Heteroepitaxial Growth for Perpendicular Magnetic Recording Media
Abstract:
Crystal structure and magnetic properties for Co-Pt-Ru alloy films and Co-Pt-Ru-oxide granular films were investigated for material to reduce the lattice mismatch between the magnetic layer and the nuclei control layer of the perpendicular magnetic recording media. Laminate stacking structure of the sample was sub/ NiFeCr (20 nm)/ Ru (20 nm)/ Co-Pt-Ru (20 nm). Amount of stacking faults (SFs) in the films was evaluated as a probability of occurring of fcc stacking, Pfcc measured by an in-plane XRD profile. As a result, it was found that; (1) hcp atomic stacking structures of the Co100-xRux alloy films were stable compared with that of Co100- xPtx alloy films for almost the all additional content x. (2) Lattice constant a and c for Co-Pt-Ru ternary alloy film could be controlled between 2.51 to 2.59 Å, and 4.07 to 4.41Å, as changing Pt and Ru content with total amount of 0 to 50 at.%, respectively. And lattice constant ratio c/a decreased from 1.62 to 1.59 with increasing Ru content more than 20 at.%. (3) Pfcc in the Co-Pt-Ru ternary alloy films were less than 0.5% for the samples with Ru content was more than 20 at.%. (4) Uniaxial magnetocrystalline anisotropy Ku could be controlled from 12.6 to 0 ×106 erg/cm³ by adding Pt and Ru with total amount of 30 at.% to a Co75Pt25 film. (5) Co-Pt-Ru-(SiO2) film with columnar structure was realized for Ar gas pressure of 4.0 Pa during sputtering.
Autors: Shintaro Hinata;Yu Suzuki;Ken Inoue;Shin Saito;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Hierarchical Decentralized Control for Enhanced Rotor Angle and Voltage Stability of Large-Scale Power Systems
Abstract:
Several hierarchical centralized control schemes for either rotor angle or voltage stability improvement have been proposed in the literature. They all rely on exchanging information between different subsystems of a large-scale power system. By contrast, in this paper, we propose a hierarchical decentralized control scheme to enhance a unified manner rotor angle and voltage stability while using metered values collected within each subsystem, without any exchange of information between subsystems. Specifically, weakly coupled coherent areas of a power system are first determined. Then, secondary control agents are implemented in each of them to detect and damp rotor angle and voltage instabilities using local synchrophasor measurements. Decentralized control laws based on Lyapunov theory are implemented on FACTS devices for achieving global rotor angle asymptotic stability. Finally, a tertiary voltage control agent provides reference settings to the secondary voltage agents and takes control actions in case the latter fail to damp voltage instabilities. We show that the proposed scheme minimizes the communication bandwidth requirement while exhibiting a system-wide situational awareness. Simulations carried out on the IEEE 118-bus system demonstrate the effectiveness of the proposed hierarchical decentralized control method.
Autors: Srivats Shukla;Lamine Mili;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4783 - 4793
Publisher: IEEE
 
» Hierarchical SCOPF Considering Wind Energy Integration Through Multiterminal VSC-HVDC Grids
Abstract:
In this paper, a hierarchical security-constrained optimal power flow (SCOPF) model is proposed for a meshed ac/multiterminal HVDC (MTDC) system with high wind penetration. The two interacting levels in the proposed model are as follows: 1) the high level is a traditional SCOPF problem in an ac system that aims to minimize total generation and security control costs; and 2) the low level is a dynamic power dispatching problem, which regulates power flow in an MTDC grid according to reference signals from the high level. Thus, the proposed method utilizes an MTDC system to provide support for the ac system by redistributing power flow across the entire grid and reducing control costs. Two modified IEEE meshed ac/dc systems are used to demonstrate the performance of the proposed method.
Autors: Ke Meng;Wang Zhang;Yujun Li;Zhao Yang Dong;Zhao Xu;Kit Po Wong;Yu Zheng;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4211 - 4221
Publisher: IEEE
 
» Hierarchical Subspace Learning Based Unsupervised Domain Adaptation for Cross-Domain Classification of Remote Sensing Images
Abstract:
We address the problem of automatic updating of land-cover maps by using remote sensing images under the notion of domain adaptation (DA) in this paper. Essentially, unsupervised DA techniques aim at adapting a classifier modeled on the source domain by considering the available ground truth and evaluate the same on a related yet diverse target domain consisting only of test samples. Traditional subspace learning based strategies in this respect inherently assume the existence of a single subspace spanning the data from both the domains. However, such a constraint becomes rigid in many scenarios considering the diversity in the statistical properties of the underlying semantic classes and problem due to data overlapping in the feature space. As a remedy, we propose an automated binary-tree based hierarchical organization of the semantic classes and subsequently introduce the notion of node-specific subspace learning from the learned tree. We validate the method on hyperspectral, medium-resolution, and very high resolution datasets, which exhibits a consistently improved performance in comparison to standard single subspace learning based strategies as well as other representative techniques from the literature.
Autors: Biplab Banerjee;Subhasis Chaudhuri;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 5099 - 5109
Publisher: IEEE
 
» High Performance Single Element MI Magnetometer With Peak-to-Peak Voltage Detector by Synchronized Switching
Abstract:
We propose a new high performance magnetometer using a single magneto-impedance (MI) sensor with a peak-to-peak voltage detector by synchronized switching (shortened: Pk-pk VD-type MI magnetometer), which is aimed to measure an extremely weak magnetic field ranging from nT ( T) to pT ( T), based upon the conventional MI magnetometer, which is used in the electronic compass. In order to enhance sensitivity and reduce noise, the Pk-pk VD-type MI magnetometer detects both the positive peak and the negative peak in induced voltage waveform of pickup coil. In this paper, for demonstrating the performances of the Pk-pk VD-type MI magnetometer, we investigate the magnetic field sensitivity and the magnetic noise spectral density. We demonstrated that the noise level of the Pk-pk VD-type MI magnetometer is lower than 2 pT/Hz for the frequency range from 1 to 100 Hz, which is much better than the conventional MI magnetometer. We discuss the noise performance of the Pk-pk VD-type MI magnetometer. According to the results obtained in this paper, we expect that this proposed MI magnetometer can be widely used for extremely weak magnetic field detection.
Autors: Jiaju Ma;Tsuyoshi Uchiyama;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» High Tunnel Magnetoresistance in Mo/CoFe/MgO Magnetic Tunnel Junction: A First-Principles Study
Abstract:
The tunnel magnetoresistance (TMR) ratio in a magnetic tunnel junction (MTJ) is influenced by heavy metal capping layer due to the interfacial effect. We report a systematic first-principles study on MTJ based on CoFe/MgO with capping layer, demonstrate that TMR ratios are sensitive to capping layer material, and show that TMR in Mo-capped MTJ is three times as high as that in Ta-capped MTJ. Besides, TMR in Mo-capped MTJ remains high at finite voltage bias. By analyzing the transmission spectrum and density of scattering states, we found that coherent transmission of state dominates the majority-spin conductance in Mo-capped MTJ, while the resonant tunneling contributes significantly in Ta-capped MTJ. The evolution of TMR for varying MgO and CoFe thickness in Mo-capped MTJ is presented. TMR oscillates as a function of CoFe thickness because of the confined wave function in ferromagnetic layer, while TMR rises with MgO thickness increasing due to the enhanced filtering effect of MgO. This work clarifies the physical mechanism on high TMR in Mo-capped MTJ, which is promising to benefit the design of spintronics device.
Autors: Jiaqi Zhou;Weisheng Zhao;Shouzhong Peng;Junfeng Qiao;Jacques-Olivier Klein;Xiaoyang Lin;Youguang Zhang;Arnaud Bournel;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» High-Accuracy Subpixel Image Registration With Large Displacements
Abstract:
This paper aims to achieve computationally efficient and high-accuracy subpixel image registration with large displacements under the rotation–scale–translation model. This paper employs the classical phase correlation algorithm and the Lucas–Kanade (LK) algorithm in a two-stage coarse-to-fine framework, for which the motivation is from the observation that the two algorithms exhibit strong complementary property between convergence range and subpixel accuracy. In this framework, the LK algorithm will also become computationally efficient owing to the small residual displacement. On the other hand, this paper takes into account the residual model with respect to the compensation scheme explicitly, and deduces formulas for the final results combination, which is expected to be closer to the true displacement vector and thus further improve the estimation accuracy. Since the compensation can be applied to either the target image or the reference image, two algorithms are presented accordingly, and analysis as well as comparison are also performed. Finally, both simulations and real image experiments are performed to verify the motivation, and the results are consistent with the analysis.
Autors: Xiangguo Li;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6265 - 6276
Publisher: IEEE
 
» High-Density Shingled Heat-Assisted Recording Using Bit-Patterned Media Subject to Track Misregistration
Abstract:
Shingled recording employing bit-patterned media when used in conjunction with heat-assisted magnetic recording can significantly enhance the recording density. This paper investigates writing of dots that are not directly under the laser pulse. Such a shifted scheme of writing allows higher densities when used with shingled recording. A further increase in the recording density can be obtained by using composite structures, comprising a superparamagnetic writing layer, and a (doped) FePt storage layer. Effect of head velocity, Curie temperature variation, track mis-registration, and dot position jitter on the standard deviation of switching distribution is studied to evaluate the designs that offer data densities as high as ~16 Tbpsi.
Autors: Aneesh Venugopal;Ali Ghoreyeshi;R. H Victora;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» High-Dimensional Pixel Composites From Earth Observation Time Series
Abstract:
High-quality and large-scale image composites are increasingly important for a variety of applications. Yet a number of challenges still exist in the generation of composites with certain desirable qualities such as maintaining the spectral relationship between bands, reduced spatial noise, and consistency across scene boundaries so that large mosaics can be generated. We present a new method for generating pixel-based composite mosaics that achieves these goals. The method, based on a high-dimensional statistic called the ‘geometric median,’ effectively trades a temporal stack of poor quality observations for a single high-quality pixel composite with reduced spatial noise. The method requires no parameters or expert-defined rules. We quantitatively assess its strengths by benchmarking it against two other pixel-based compositing approaches over Tasmania, which is one of the most challenging locations in Australia for obtaining cloud-free imagery.
Autors: Dale Roberts;Norman Mueller;Alexis Mcintyre;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6254 - 6264
Publisher: IEEE
 
» High-Efficiency Microwave Rectifier With Less Sensitivity to Input Power Variation
Abstract:
In this letter, a novel microwave rectifier based on a power recycling network (PRN) is proposed, which features less sensitivity to input power variation. The PRN is connected to the microwave input of two parallel subrectifiers, realizing better matching over a wide power range. For validation, a 2.45-GHz rectifier incorporating the PRN is designed and implemented. The measured results show that the RF-dc conversion efficiency maintains over 50% and 70% within the input power range 10.5–31.8 and 21.7–30.1 dBm, respectively. Compared with the counterpart without the PRN, the operating power range is extended without degrading the maximum efficiency.
Autors: Zhi-Xia Du;Xiu Yin Zhang;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Nov 2017, volume: 27, issue:11, pages: 1001 - 1003
Publisher: IEEE
 
» High-Frequency Magnetic Thin-Film Inductor Integrated on Flexible Organic Substrates
Abstract:
This paper presents integrated inductors with Co-Zr-Ta-B (CZTB) thin films on flexible organic substrates for MHz–GHz applications. This paper demonstrated the fabrication and characterization of magnetic thin-film inductors on flexible organic substrates, such as polyimide and Ajinomoto build-up film thin films. These films have thicknesses of only tens of micrometer and thus are very flexible compared to the same inductor structures fabricated on rigid substrates, such as quartz. The magnetic films on flexible substrates were observed to maintain similar magnetic properties compared with those on Si substrate, but with greater coercivity likely due to the increased roughness of the substrate surface. The fabricated thin-film inductors on organic substrates with inductance , measured by RF characteristics, have shown significantly increased inductance compared to air-core inductors (without magnetic core materials). This paper also demonstrated a high frequency response, clearly over GHz, consistent with the CZTB type of materials. The frequency response, as well as inductance and Q values, remains similar even after many iterations of bending to a large degree, indicating the robustness of the inductor on flexible organic substrates, as well as that of the magnetic thin films.
Autors: Hao Wu;Mahmoud Khdour;Priyanka Apsangi;Hongbin Yu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 7
Publisher: IEEE
 
» High-Frequency Properties of Fe-4.5 Wt% Si Powders With an Insulating Layer Synthesized by a Modified Dew-Point Treatment
Abstract:
The frequency for wireless power chargers is in the range of 100–205 kHz when using MnZn ferrite and NiZn ferrite. Compared to ferromagnetic metals, these ferrites have higher resistivity, which reduces the eddy loss at high frequencies, though they also have lower magnetization values that limit the distance and the direction between the receiver and transmitter units. Thus, there is a strong demand for the development of a new metallic magnetic sheet that can suppress the eddy-current loss in the high-frequency range. To meet this demand, a modified dew-point insulation coating method for Fe-4.5 wt% Si powders was assessed and the high-frequency properties of green compacts consisting of these powders were investigated. As a result, a thin high-resistivity layer was successfully coated onto the powders. In addition, both eddy-current loss and hysteresis loss of their compacts were dramatically reduced in the high-frequency region.
Autors: Kwiyoung Lee;Moosung Choi;Jongryoul Kim;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» High-Performance GaN-Based LEDs on Si Substrates: The Utility of Ex Situ Low-Temperature AlN Template With Optimal Thickness
Abstract:
Ex situ low-temperature (LT)-AlN templates are employed to realize GaN-based light-emitting diodes (LEDs) on Si substrates by the combination of pulsed laser deposition and metal organic chemical vapor deposition. The influence of ex situ LT-AlN template thickness on the properties and performance of as-grown LEDs has been carefully studied. The LED wafer grown on 70-nm-thick ex situ LT-AlN template exhibits a crack-free surface, good crystalline quality, and excellent multiple quantum wells (MQWs) structural property. The LED chips fabricated with lateral structure show the highest light output power of 70.2 mW at an injection current of 300 mA. Through optimizing the thickness of ex situ LT-AlN template, the light output power is greatly improved by 39%. Theoretical analysis has been taken to study the enhancement mechanism of luminous intensity in this LED. It reveals that the residual stress in as-grown wafers is significant to enhance the luminescence of LEDs. The largest residual tensile stress in the LED presents great potential to enhance the carrier injection and transportation, increase the carrier concentrations, and improve the radiative recombination intensity in MQWs, which is crucial to improve the luminous intensity of LEDs.
Autors: Haiyan Wang;Zhiting Lin;Yunhao Lin;Wenliang Wang;Guoqiang Li;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4540 - 4546
Publisher: IEEE
 
» High-Performance Single-Electron Transistor Based on Metal–Organic Complex of Thiophene: First Principle Study
Abstract:
The ab initio perspective based on density functional theory and nonequilibrium Green’s function for the modeling of single electron transistors (SETs) based on thiol-ended thiophene and chromium complex of thiol-ended thiophene and their functioning in the Coulomb blockade regime has been discussed. Both thiol-ended thiophene molecule and its chromium complex have been analyzed for the charge stability and conductance dependence on the gate voltage and source–drain bias. The charging energies for the isolated and SET environment for both the islands have been calculated and discussed. Also, the effect of orientation and the dielectric medium has been studied in order to increase the conductance of SET with the combination of a particular orientation and a dielectric medium. The effect of different electrodes on charge stability diagram has also been studied. The analysis shows a remarkably improved conductance for the chromium complex of thiol-ended thiophene molecule in the SET environment than the thiol-ended thiophene molecule in the SET environment resulting in a fast switching metal–organic SET.
Autors: Anu;Archana Sharma;Md. Shahzad Khan;Anurag Srivastava;Mushahid Husain;Mohd. Shahid Khan;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4628 - 4635
Publisher: IEEE
 
» High-Power Evanescently Coupled Waveguide MUTC Photodiode With >105-GHz Bandwidth
Abstract:
We demonstrate high-speed and high-power evanescently coupled waveguide integrated modified unitraveling carrier photodiodes. Over 105-GHz bandwidth along with 2 and 1.3 dBm RF output power at 100 and 105 GHz, respectively, has been achieved.
Autors: Qinglong Li;Keye Sun;Kejia Li;Qianhuan Yu;Patrick Runge;Willi Ebert;Andreas Beling;Joe C. Campbell;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4752 - 4757
Publisher: IEEE
 
» High-Precision Resolver-to-Velocity Converter
Abstract:
Accurate velocity estimation for rotary control over a large velocity range has been a challenge. In this paper, we propose a virtually analog resolver-to-velocity converter that applies trigonometric transformations to the resolver outputs. We also present hardware that extends the output range of a previously proposed resolver-to-position circuit from 90° to 360°. The position and velocity outputs of the two circuits are evaluated against the position and velocity obtained from an optical encoder using the backward difference differentiation technique. Recommendations for tuning and improvements in the circuitry are also provided.
Autors: Leonam Pecly;Ryan Schindeler;Daniel Cleveland;Keyvan Hashtrudi-Zaad;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2917 - 2928
Publisher: IEEE
 
» High-Precision, Mixed-Signal Mismatch Measurement of Metal–Oxide–Metal Capacitors
Abstract:
This brief presents a high-precision, mixed-signal mismatch measurement technique for metal–oxide–metal capacitors. The proposed technique incorporates a switched-capacitor op amp within the measurement circuit to significantly improve the measurement precision while relaxing the resolution requirement on the backend analog-to-digital converter (ADC). The proposed technique is also robust against multiple types of errors. A detailed analysis is presented to quantify the sensitivity improvement of the proposed technique over the conventional one. In addition, this brief proposes a multiplexing technique to measure a large number of capacitors in a single chip and a new layout to improve matching. A prototype fabricated in 180 nm technology demonstrates the ability to sense capacitor mismatch standard deviation as low as 0.045% with excellent repeatability, all without the need of a high-resolution ADC.
Autors: Danilo Bustamante;Devon Janke;Eric Swindlehurst;Shiuh-Hua Wood Chiang;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Nov 2017, volume: 64, issue:11, pages: 1272 - 1276
Publisher: IEEE
 
» High-Resolution Microwave Breast Imaging Using a 3-D Inverse Scattering Algorithm With a Variable-Strength Spatial Prior Constraint
Abstract:
Microwave inverse scattering is an exploratory imaging modality with potential for several clinical breast imaging applications, including density evaluation, cancer detection, and treatment monitoring. However, conventional regularization techniques used to solve the ill-posed inverse problem typically result in blurred boundaries between tissue structures exhibiting dielectric contrast, thereby limiting the effective resolution. We present a method to improve microwave breast imaging resolution that incorporates a priori information about the boundaries between different tissues in the breast into the inverse scattering algorithm. This spatial prior information can be derived from another imaging modality, such as magnetic resonance imaging. Our method exploits the fact that the dielectric properties within a tissue type exhibit low to moderate variability by favoring solutions to the inverse scattering problem, which have small variations in dielectric properties within each tissue region. The amount of variation tolerated in each regions is controlled by a spatial prior constraint parameter. We demonstrate the feasibility of the method by imaging detailed, anatomically inspired numerical 3-D breast phantoms. The performance in the presence of different levels of noise and for different choices of the constraint parameter is evaluated. We also demonstrate the robustness of the algorithm with respect to errors in the spatial prior information.
Autors: Luz Maria Neira;Barry D. Van Veen;Susan C. Hagness;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6002 - 6014
Publisher: IEEE
 
» High-Resolution Parameter Estimation for Time-Varying Double Directional V2V Channel
Abstract:
This paper describes a high-resolution parameter estimation algorithm applied to the vehicle-to-vehicle (V2V) multi-dimensional channel measurements. The algorithm, which is based on a maximum likelihood estimator, jointly estimates parameters of multipath components, such as time-of-arrival, direction of departure, direction of arrival, and Doppler shift. It serves to provide a comprehensive understanding of the V2V propagation channel. We propose computationally attractive methods to initialize parameters in the global search and evaluate key components in the local optimization. We also apply the algorithm to actual V2V channel measurement data. The results suggest an overall good performance of the estimator, where 80% of the snapshots have a diffuse power ratio less than 20% and the dominant specular paths match well with the environment and dynamics of the measurement.
Autors: Rui Wang;Olivier Renaudin;C. Umit Bas;Seun Sangodoyin;Andreas F. Molisch;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7264 - 7275
Publisher: IEEE
 
» High-Resolution Simultaneous Measurement of Strain and Temperature Using $pi$-Phase-Shifted FBG in Polarization Maintaining Fiber
Abstract:
We present a high-resolution simultaneous strain and temperature measurement scheme using -phase-shifted fiber Bragg grating written in PANDA-type polarization maintaining fiber. Two optical parameters, the Bragg frequency and the birefringence-introduced frequency difference, are measured to perform the discrimination of strain and temperature. A double-sideband interrogation method together with a cross-feedback technique is introduced, which significantly reduces the measurement error in birefringence-introduced frequency difference, and hence improves the sensing resolution of strain and temperature. In the demonstration experiment, simultaneous measurement of strain and temperature with resolutions of 0.018 and 0.0014 C respectively is realized.
Autors: Jiageng Chen;Qingwen Liu;Zuyuan He;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:22, pages: 4838 - 4844
Publisher: IEEE
 
» High-Response Identifiable Gas Sensor Based on a Gas-Dielectric ZnPc Nanobelt FET
Abstract:
Gas sensors based on organic semiconductor have recently attracted much attention due to their inherent advantages, especially excellent flexibility and good selectivity. However, the gas species identification with high sensing response remains a key subject for organic gas sensors. Herein, a ZnPc single nanobelt field-effect transistor with the gas dielectric was fabricated and exhibited excellent gas sensing performance at room temperature. The sensors show the high response with 220% to 10 ppm NO2 and 3566% to 20 ppm H2S, and the low detection limit down to 50 ppb towards NO2/H2S, which surpass most reported room-temperature organic-based NO2/H2S sensors. Further, our single device realized accurate gas selective identification among NO2, SO2 and H2S with 92% success ratio in LDA feature space.
Autors: Zhiqi Song;Qingxin Tang;Yanhong Tong;Yichun Liu;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1586 - 1589
Publisher: IEEE
 
» Higher Density Melt Spun Isotropic Magnets
Abstract:
Traditional techniques for consolidating melt spun RE–Fe–B powders tend to incur significant volumes of non-magnetic material, like porosity and the polymer binder. Several alternative consolidation techniques are being studied in an effort to reduce the non-magnetic component and improve the overall performance of such magnets. Rapid electric discharge sintering (REDS) offers one method of fully densifying melt spun RE–Fe–B flakes in a rapid and efficient way with minimal material wastage. This paper attempted to consolidate stoichiometric RE2Fe14B, RE-lean and RE-rich compositions with REDS, spark plasma sintering and conventional hot-tool techniques. The relative magnetic performance and physical condition of the samples are compared. The success of a consolidation technique depends on the melt spun RE–Fe–B chemistry, the relative density of the final compact, and the ability to avoid excessive grain growth in the magnet microstructure.
Autors: Badrinath Veluri;David Brown;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Highly Birefringent Terahertz Waveguide Formed With Dual-Subwavelength Polymer Wires
Abstract:
We propose a highly birefringent terahertz (THz) waveguide, which is formed with two touching subwavelength polymer wires. The waveguide can provide a high modal birefringence larger than 0.01 over a wide frequency range, and a maximum birefringence up to 0.0525 is achieved when the waveguide is made of Topas. Different from other THz birefringent waveguides, a simple scaling rule exists for the proposed birefringent waveguide so that the waveguide can be designed easily for any desired operation frequency to obtain the maximum birefringence. Moreover, when the maximum birefringence takes place, a high coupling efficiency of 93%, a low absorption loss of 0.04 and 0.03 cm-1 for x- and y-polarizations, and a negligible bending loss are demonstrated in our simulations. Finally, the influence of material index is further examined. It is found that as the refractive index of the waveguide material increases, the magnitude of birefringence increases as well, while the frequency at which the maximum birefringence occurs will shift toward the lower region.
Autors: Chih-Hsien Lai;Zong-Sheng Xu;Hsuan-Yu Chen;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4641 - 4649
Publisher: IEEE
 
» Highly Sensitive Acetone Sensor Based on Pd/AlGaN/GaN Resistive Device Grown by Plasma-Assisted Molecular Beam Epitaxy
Abstract:
Highly sensitive acetone sensing performance of Pd/AlGaN/GaN resistive devices in the temperature range of 100 °C–250 °C and in the detection range of 100–1000 ppm was reported. A plasma-assisted molecular beam epitaxy was used to grow the AlGaN/GaN heterostructure on Si (111) substrate. Structural characterization of the grown epilayers was performed through double-crystal X-ray diffraction whereas atomic force microscopy was used to obtain the roughness of the sensing surface. Resistive mode configuration of the sample was tested toward acetone in the detection range of 100–1000 ppm and in the temperature range of 100 °C–250 °C. The optimum temperature was found to be 150 °C with response magnitude ~95% for the acetone concentration of 1000 ppm. The sensor response time and recovery time were found to be in the range of ~18–44 s and ~25–109 s, respectively. The cross-sensitivity of the device with other interfering species such as butanone, benzene, toluene, and xylene attributed to good acetone selectivity of the devices. Acetone sensing as well as current transport of the Pd/AlGaN/GaN devices was illustrated with effect including Langmuir adsorption–desorption kinetics and Schottky barrier height between Pd/AlGaN interfaces.
Autors: Subhashis Das;Saptarsi Ghosh;Rahul Kumar;Ankush Bag;Dhrubes Biswas;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4650 - 4656
Publisher: IEEE
 
» Highly Sensitive ppb Level Methanol Sensor by Tuning C:O Ratio of rGO-TiO2 Nanotube Hybrid Structure
Abstract:
In this paper, ppb level methanol sensing by a hybrid gas sensor device based on reduced graphene oxide (rGO) and TiO2 nanotubes is reported. Tuning of carbon to oxygen ratio, in rGO layers, was found to be very effective in modulating the sensor response. The C:O ratio was tuned by varying the voltage (11–31 V) during the electro-deposition of rGO (on top of the TiO2 nanotube matrix) and was confirmed by Raman spectroscopy and X-ray photoelectron spectroscopy. Due to variations in the C:O ratio in rGO, the barrier height of rGO-TiO2 nanotube junctions and etch hole dimension on rGO layer were varied. Judicious optimization of these two pivotal parameters resulted in the sensor device (for rGO deposition voltage of 16 V), capable of detecting ppb level (up to 62 ppb) methanol efficiently. The sensor showed ∼16%, ∼59%, and ∼94% response magnitude for 62 ppb, 1 ppm, and 200 ppm concentrations, respectively. A comprehensive discussion elucidating the role of rGO-TiO2 NTs junctions (with a tunable C:O ratio) has also been presented correlating the experimental findings.
Autors: Debanjan Acharyya;Snehanjan Acharyya;Kuoyou Huang;Peifang Chung;Monshu Ho;Partha Bhattacharyya;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 1122 - 1128
Publisher: IEEE
 
» HIRAD Brightness Temperature Image Geolocation Validation
Abstract:
The Hurricane Imaging Radiometer (HIRAD) is an airborne microwave radiometer developed to provide wide-swath hurricane surface wind speed and rain rate imagery for scientific research. This letter presents a geometric evaluation of the brightness temperature (Tb) images produced by HIRAD for high-contrast land/water targets. Methodologies used to validate geolocation accuracy and spatial resolution are discussed, and results are presented to provide quantitative pixel geolocation accuracy and the effective image spatial resolution of the Tb image.
Autors: Saleem Sahawneh;W. Linwood Jones;Sayak K. Biswas;Daniel Cecil;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1908 - 1912
Publisher: IEEE
 
» HL-PCM: MLC PCM Main Memory with Accelerated Read
Abstract:
Multi-Level Cell Phase Change Memory (MLC PCM) is a promising candidate technology for DRAM replacement in main memory of modern computers. Despite of its high density and low power advantages, this technology seriously suffers from slow read and write operations. While prior works extensively studied the problem of slow write, this paper targets high read latency problem in MLC PCM and introduces an architecture mechanism to overcome it. To this end, we rely on the fact that reading different bits from an MLC cell takes different latencies, i.e., for a 2-bit MLC, reading its Most-Significant Bit (MSB) is fast, while reading its Least-Significant Bits (LSBs) is slower. We then propose Half-Line PCM (HL-PCM), a novel memory architecture that leverages this non-uniformity in reading MLC PCM’s content to send a requested memory block to the processor in different cycles–it sends half of a memory block to the processor ahead of the other half. If the processor requested a word belonging to the first half, it can resume its execution on receiving the first half, while the other half has not sent yet and scheduled to be received by the memory controller later. HL-PCM is easy and simple to implement, i.e., it needs minor modifications at memory controller, the search/evict policies at last level cache, as well as data layout in main memory. Our experimental results show that the proposed design improves the average memory access latency by 33–43 percent and program’s execution time by 23 percent, on average, while incurring negligible overhead at memory controller and PCM DIMM, in a 16-core chip multiprocessor (CMP) running memory-intensive benchmarks.
Autors: Mohammad Arjomand;Amin Jadidi;Mahmut T. Kandemir;Anand Sivasubramaniam;Chita R. Das;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Nov 2017, volume: 28, issue:11, pages: 3188 - 3200
Publisher: IEEE
 
» Holomorphic Embedding Load-Flow Modeling of Thyristor-Based FACTS Controllers
Abstract:
Development of appropriate load flow model of Flexible AC Transmission System (FACTS) devices is an important issue for proper planning, control, and protection of power system. Holomorphic Embedding Load-Flow Method (HELM) is a novel technique for solving load flow nonlinear equations which overcomes the numerical problems faced by traditional iterative techniques. In order to evaluate the effects of FACTS devices in load flow problem by HELM technique, it is necessary to develop HELM modeling of these devices. This paper presents HELM modeling of Thyristor-based FACTS controllers, i.e., Static Var Compensator (SVC), Thyristor Controlled Switched Capacitor (TCSC), Thyristor Controlled Voltage Regulator (TCVR), and Thyristor Controlled Phase Angle Regulator (TCPAR). In this modeling, white germ solution is investigated along with recursive formula and controlling FACTS devices operation bounds.
Autors: Mohsen Basiri-Kejani;Eskandar Gholipour;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4871 - 4879
Publisher: IEEE
 
» Homogenization of Bi-Isotropic Multilayered Metamaterial Structures
Abstract:
In this paper, we present new expressions of the effective constitutive parameters of bi-isotropic multilayered structure having an arbitrary number of layers and different thicknesses. The present method uses the decomposition scheme, and the commutativity between the homogenization process and the decomposition scheme is supposed. The effective constitutive parameters of the initial structure are evaluated as a function of the two equivalent media's parameters. In order to validate the proposed analytical expressions, the numerical results are compared to the homogenization's multiscale method.
Autors: Ouail Ouchetto;Brahim Essakhi;Saïd Jai-Andaloussi;Saad Zaamoun;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 946 - 953
Publisher: IEEE
 
» Homogenization of the Spatial Sensitivity of Electrostatic Sensors for the Flow Measurement of Pneumatically Conveyed Solids in a Square-Shaped Pipe
Abstract:
The spatial sensitivity of an electrostatic sensor is recognized as an important factor that affects the accuracy of solids flow measurement in a pneumatic conveying pipe. However, the distribution of the spatial sensitivity is generally inhomogeneous due to the physical structure of the electrostatic sensor and the inherent electrostatic sensing mechanism. This paper proposes a sensitivity homogenization method based on differential measurement, i.e., using the differential outputs from two electrodes with different axial widths. The validity of the sensitivity homogenization method for a square-shaped electrostatic sensing head, which consists of strip-shaped electrode arrays with different widths, is validated through mathematical analysis. Furthermore, the response of the electrostatic sensing head incorporating the sensitivity homogenization method to roping flow regimes was evaluated on a gravity-fed solids flow test rig. Results from both modeling and experimental tests indicate that the homogeneity of the spatial sensitivity is improved significantly. The mean non-uniformity of the outputs from the sensing head is 11.7% as a result of the homogenization method.
Autors: Shuai Zhang;Yong Yan;Xiangchen Qian;Rong Huang;Yonghui Hu;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7516 - 7525
Publisher: IEEE
 
» Hot, mobile, and under control [Resources]
Abstract:
When I first learned to solder, I did so using a cheap iron, not realizing how atrocious such things are. It wasn't until several years later that I purchased a temperature-controlled soldering station. These use thermal feedback to keep the tip at a set temperature, and I soon learned that good solder joints are easy to make when you have good equipment. I've had that very same Weller WTCPN soldering station for almost four decades now, having forsaken non-temperature-controlled irons completely. This stance on soldering irons did, however, put me in a quandary recently when I started to explore the options for cordless soldering irons. Cordless irons are essential for those times when you need to solder something and there's no power outlet available. Yet I could not find a cordless iron for sale that had temperature control. So I figured I'd build myself one. My fondness for my faithful Weller soldering station dictated the first design criterion—it had to provide the same quality temperature control—and also suggested a strategy to attain that goal: Weller's Magnastat system. Let me explain. Weller long ago devised a clever way to provide temperature feedback and control without using any electronics. It's based on the physics of ferromagnetic materials, which lose their magnetism when heated above a certain temperature, known as the Curie point. Weller's Magnastat system uses three magnetic components near the tip: two inside a normally open switch, the other built into the tip itself. The components inside the switch (one movable) have a very high Curie point, whereas the one in the tip has a Curie point equal to the desired soldering temperature.
Autors: David Schneider;
Appeared in: IEEE Spectrum
Publication date: Nov 2017, volume: 54, issue:11, pages: 17 - 18
Publisher: IEEE
 
» How does passive optical network tackle radio access network evolution?
Abstract:
This paper describes full service access network operator group perspectives on the feasibility of optical access networks to carry radio access network traffic for the existing and future mobile generations. The paper discusses topics related to the evolution of radio access interfaces, such as backhaul, midhaul, and fronthaul, their transmission through optical distribution networks, and passive optical network technology feasibility based on both time and wavelength division multiplexing and multiple accesses. Technology extensions are also discussed to provide guidance for future research.
Autors: Philippe Chanclou;Hiroo Suzuki;Jin Wang;Yiran Ma;Mauro Renato Boldi;Kazuki Tanaka;Seungjoo Hong;Claudio Rodrigues;Luiz Anet Neto;Jiang Ming;
Appeared in: IEEE/OSA Journal of Optical Communications and Networking
Publication date: Nov 2017, volume: 9, issue:11, pages: 1030 - 1040
Publisher: IEEE
 
» How Software Is Changing the Automotive Landscape
Abstract:
A look at the creation and distribution of automotive navigation software at TomTom shows how automotive software has changed and might further change.
Autors: Hans Aerts;Han Schaminée;
Appeared in: IEEE Software
Publication date: Nov 2017, volume: 34, issue:6, pages: 7 - 12
Publisher: IEEE
 
» How Statistical Signal Processing Was Used to Define the MH370 Search Zone
Abstract:
Malaysian Airlines flight MH370 from Kuala Lumpur, Malaysia, to Beijing, China, departed on 8 March 2014 carrying 239 passengers and crew. Communications with the aircraft were lost as it transitioned from Malaysian to Vietnamese airspace, and the subsequent search and rescue efforts were unable to find the missing aircraft. Radar data indicates that the aircraft turned to the southwest and crossed Malaysia and then f lew northwest along the Malacca Strait. When the aircraft moved beyond radar coverage, it was still carrying enough fuel to fly for several hours, and the size of the reachable area is almost 20% of the surface of the Earth. Although communications were lost early in flight, there was an active communications link between the aircraft and a satellite; metadata from signaling messages on the link provide information about where the aircraft was, even though no user data was communicated.
Autors: Samuel Davey;Neil Gordon;Ian Holland;Mark Rutten;Jason Williams;
Appeared in: IEEE Potentials
Publication date: Nov 2017, volume: 36, issue:6, pages: 32 - 37
Publisher: IEEE
 
» How to Read Many-Objective Solution Sets in Parallel Coordinates [Educational Forum]
Abstract:
Rapid development of evolutionary algor ithms in handling many-objective optimization problems requires viable methods of visualizing a high-dimensional solution set. The parallel coordinates plot which scales well to high-dimensional data is such a method, and has been frequently used in evolutionary many-objective optimization. However, the parallel coordinates plot is not as straightforward as the classic scatter plot to present the information contained in a solution set. In this paper, we make some observations of the parallel coordinates plot, in terms of comparing the quality of solution sets, understanding the shape and distribution of a solution set, and reflecting the relation between objectives. We hope that these observations could provide some guidelines as to the proper use of the parallel coordinates plot in evolutionary manyobjective optimization.
Autors: Miqing Li;Liangli Zhen;Xin Yao;
Appeared in: IEEE Computational Intelligence Magazine
Publication date: Nov 2017, volume: 12, issue:4, pages: 88 - 100
Publisher: IEEE
 
» HTS Dual-Stator Spoke-Type Linear Vernier Machine for Leakage Flux Reduction
Abstract:
In this paper, a high-temperature superconductor dual-stator spoke-type linear vernier machine (HTS-DSSLVM) is proposed for wave energy extraction, which offers high-thrust force density and better power factor due to leakage flux reduction. HTS bulks are introduced in between the split flux modulation teeth to shield the leakage flux and hence improve the force density and power factor. The electromagnetic characteristics of the machine are comprehensively investigated and compared with that of a recently presented dual-stator spoke-type linear vernier machine (DSSLVM). The results show that the proposed machine yields higher thrust force and better power factor than the DSSLVM due to reduced leakage flux in the proposed machine.
Autors: Noman Baloch;Salman Khaliq;Byung-Il Kwon;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Humidity Sensor Based on Fabry–Perot Interferometer and Intracavity Sensing of Fiber Laser
Abstract:
A humidity sensor based on Fabry–Perot interferometer (FPI) and intracavity sensing of a fiber ring laser is proposed and experimentally demonstrated. A compact humidity-sensitive fiber-optic FPI is developed and inserted in a fiber ring laser. Because the output power of the fiber laser is modulated by the reflection loss of the FPI at different ambient humidity, intracavity humidity sensing is induced. The experiment shows that the relative output power of the fiber laser has a good linear response to ambient humidity from 25%RH to 95%RH and the humidity sensitivity of 0.202 dB/%RH is obtained with a narrow 3-dB bandwidth and high signal-to-noise ratio. Furthermore, the excellent performance of the sensor for remote humidity detection is demonstrated. The sensor also shows a low temperature cross-sensitivity, fast time response, and good stability. The proposed sensor has a great potential in high-capacity sensor network and remote detections.
Autors: Jia Shi;Degang Xu;Wei Xu;Yuye Wang;Chao Yan;Chao Zhang;Dexian Yan;Yixin He;Longhuang Tang;Weihong Zhang;Tiegen Liu;Jianquan Yao;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4789 - 4795
Publisher: IEEE
 
» HVDC Systems in Smart Grids
Abstract:
The use of direct current (dc) power networks, either at high voltage or at medium voltage, is being increasingly seen in modern smart grids. This is due to the flexible control possible with dc and its ability to transmit and distribute power under circumstances where alternating current (ac) networks are either unable to, or less economic. This paper provides an overview of the evolution of high-voltage dc (HVDC) transmission from early Thury systems, to modern ultrahigh-voltage dc and multiterminal voltage–source converter systems. The operation of both current–source and voltage–source systems is discussed, along with modeling requirements. The paper provides a snapshot of the state of the art of HVDC with copious references to enable in-depth reading. Key developments over the last 20 years are highlighted. Issues surrounding multiterminal operation and dc protection are explained, along with drivers in economics and policy. This will inform HVDC integration into smart grids.
Autors: Mike Barnes;Dirk Van Hertem;Simon P. Teeuwsen;Magnus Callavik;
Appeared in: Proceedings of the IEEE
Publication date: Nov 2017, volume: 105, issue:11, pages: 2082 - 2098
Publisher: IEEE
 
» Hybrid Analog–Digital Precoding Design for Secrecy mmWave MISO-OFDM Systems
Abstract:
Millimeter-wave large-scale antenna systems typically apply hybrid analog–digital precoders to reduce hardware complexity and power consumption. In this paper, we design hybrid precoders for physical-layer security under two types of channel knowledge. With full channel knowledge at transmitter, we provide sufficient conditions on the minimum number of RF chains needed to realize the performance of the fully digital precoding. Then, we design the hybrid precoder to maximize the secrecy rate. By maximizing the average projection between the fully digital precoder and the hybrid precoder, we propose a low-complexity closed-form hybrid precoder. We extend the conventional projected maximum ratio transmission scheme to realize the hybrid precoder. Moreover, we propose an iterative hybrid precoder design to maximize the secrecy rate. With partial channel knowledge at transmitter, we derive a secrecy outage probability upper-bound. The secrecy throughput maximization is converted into a sequence of secrecy outage probability minimization problems. Then, the hybrid precoder is designed to minimize the secrecy outage probability by an iterative hybrid precoder design. Performance results show the proposed hybrid precoders achieve performance close to that of the fully digital precoding at low and moderate signal-to-noise ratios (SNRs), and sometimes at high SNRs depending on the system parameters.
Autors: Yahia R. Ramadan;Hlaing Minn;Ahmed S. Ibrahim;
Appeared in: IEEE Transactions on Communications
Publication date: Nov 2017, volume: 65, issue:11, pages: 5009 - 5026
Publisher: IEEE
 
» Hybrid Attitude and Gyro-Bias Observer Design on $SO(3)$
Abstract:
This paper presents an approach for the design of globally exponentially stable hybrid attitude and gyro-bias observers on . First, we propose a hybrid observer developed in a generic manner involving a generic family of potential functions with specific properties. Thereafter, we present a design method for such potential functions via an appropriate angular warping transformation applied to a new potential function on . This results in a hybrid observer that uses directly body-frame measurements of known inertial vectors.
Autors: Soulaimane Berkane;Abdelkader Abdessameud;Abdelhamid Tayebi;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 6044 - 6050
Publisher: IEEE
 
» Hybrid Vehicle Energy Management: Singular Optimal Control
Abstract:
Hybrid vehicle energy management is often studied in simulation as an optimal control problem. Under strict convexity assumptions, a solution can be developed using Pontryagin's minimum principle. In practice, however, many engineers do not formally check these assumptions resulting in the possible occurrence of so-called unexplained “numerical issues.” This paper intends to explain and solve these issues. Due to the binary controlled-state variable considered (e.g., switching on/off an internal combustion engine) and the use of a lookup table with linear interpolation (e.g., engine fuel consumption map), the corresponding Hamiltonian function can have multiple minima. Optimal control is not unique. Moreover, it is defined as being singular. Consequently, an infinite number of optimal state trajectories can be obtained. In this paper, a control law is proposed to easily construct a few of them.
Autors: Sébastien Delprat;Theo Hofman;Sébastien Paganelli;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9654 - 9666
Publisher: IEEE
 
» Hypergraph-Based Binary Locally Repairable Codes With Availability
Abstract:
We study a hypergraph-based code construction for binary locally repairable codes (LRCs) with availability. A symbol of a code is said to have -availability if it can be recovered from disjoint repair sets of other symbols, each set of size at most . We refer a systematic code to an LRC with -availability if its information symbols have -availability and a code to an LRC with -availability if its all symbols have -availability. We construct binary LRCs with -availability from linear -uniform -regular hypergraphs. As a special case, we also construct binary LRCs with -availability from labeled linear -uniform -regular hypergraphs. Moreover, we extend the hypergraph-based codes to increase the minimum distance. All the proposed codes achieve a well-known Singleton-like bound with equality.
Autors: Jung-Hyun Kim;Hong-Yeop Song;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2332 - 2335
Publisher: IEEE
 
» Hyperspectral Band Selection Using Improved Classification Map
Abstract:
Although it is a powerful feature selection algorithm, the wrapper method is rarely used for hyperspectral band selection. Its accuracy is restricted by the number of labeled training samples and collecting such label information for hyperspectral image is time consuming and expensive. Benefited from the local smoothness of hyperspectral images, a simple yet effective semisupervised wrapper method is proposed, where the edge preserved filtering is exploited to improve the pixel-wised classification map and this in turn can be used to assess the quality of band set. The property of the proposed method lies in using the information of abundant unlabeled samples and valued labeled samples simultaneously. The effectiveness of the proposed method is illustrated with five real hyperspectral data sets. Compared with other wrapper methods, the proposed method shows consistently better performance.
Autors: Xianghai Cao;Cuicui Wei;Jungong Han;Licheng Jiao;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2147 - 2151
Publisher: IEEE
 
» Hyperspectral Image Classification via Low-Rank and Sparse Representation With Spectral Consistency Constraint
Abstract:
In this letter, a low-rank and sparse representation classifier with a spectral consistency constraint (LRSRC-SCC) is proposed. Different from the SRC that represents samples individually, LRSRC-SCC reconstructs samples jointly and is able to capture the local and global structures simultaneously. In this proposed classifier, an adaptive spectral constraint is imposed on both the low-rank and sparse terms so as to better reveal the data structure and enhance its discriminative power. In addition, the alternating direction method is introduced to solve the underlying minimization problem, in which, more importantly, the subobjective function associated with the low-rank term is optimized based on the rank equivalence between a matrix and its Gram matrix, resulting in a closed-form solution. Finally, LRSRC-SCC is extended to LRSRC-SCCE for fully exploiting the spatial information. Experimental results on two hyperspectral data sets demonstrate that the proposed LRSRC-SCC and LRSRC-SCCE methods outperform some state-of-the-art methods.
Autors: Lei Pan;Heng-Chao Li;Hua Meng;Wei Li;Qian Du;William J. Emery;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2117 - 2121
Publisher: IEEE
 
» Hyperspectral Imagery Denoising by Deep Learning With Trainable Nonlinearity Function
Abstract:
Hyperspectral images (HSIs) can describe subtle differences in the spectral signatures of objects, and thus they are effective in a wide array of applications. However, an HSI is inevitably contaminated with some unwanted components like noise resulting in spectral distortion, which significantly decreases the performance of postprocessing. In this letter, a deep stage convolutional neural network (CNN) with trainable nonlinearity functions is applied for the first time to remove noise in HSIs. Besides the fact that the weight and bias matrices are learned from cubic training clean-noisy HSI patches, the nonlinearity functions in each stage are also trainable, which differ from the conventional CNN with a fixed nonlinearity function. Compared with the state-of-the-art HSI denoising methods, the experimental results on both synthetic and real HSIs confirm that the proposed method can obtain a more effective and efficient performance.
Autors: Weiying Xie;Yunsong Li;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1963 - 1967
Publisher: IEEE
 
» Hyperspectral Pansharpening With Guided Filter
Abstract:
A new hyperspectral (HS) pansharpening method based on guided filter is proposed in this letter. The proposed method, which obtains the spatial detail difference of each band successively, is different from the traditional component substitution method. The detail information of each band is extracted at first. Then, the panchromatic (PAN) image is sharpened to enhance the details. The spatial information difference between the enhanced PAN image and the detail information of each band is obtained using the guided filter, without causing spectral and spatial distortion. In order to reduce spectral distortion and add enough spatial information, the injection gains matrix is generated. The fused HS image is finally achieved by injecting the corresponding spatial difference into each band of the interpolated HS image. Experiments demonstrate that the proposed method can obtain superior performance in terms of subjective and objective evaluations.
Autors: Jiahui Qu;Yunsong Li;Wenqian Dong;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2152 - 2156
Publisher: IEEE
 
» Hyperthermic Effects of FeCoNi-Coated Glass Fibers in Alternating Magnetic Field
Abstract:
FeCoNi-coated glass fibers were synthesized using the electroless plating method, and the hyperthermic effects of FeCoNi-coated glass fibers in alternating magnetic fields were evaluated. The thickness of the coated FeCoNi was approximately on glass fibers with a diameter of approximately 15–. The saturation magnetization was approximately 150 emu/g. The heat elevations of FeCoNi-coated glass fibers were measured with the increasing number of fibers (4, 8, 12, 16, and 20 pieces of fibers) in silicon oil under an alternating magnetic field (AMF) at different intensities and frequencies. The elevated equilibrium temperatures linearly increased from 34.3 °C to 55.9 °C with an increasing number of FeCoNi-coated glass fibers from 4 to 20 pieces under an AMF of 105 Oe and 250 kHz. The specific loss power (SLP) was approximately 30 W/g. The heat behavior was examined as a function of the AMF and frequency. The AMF intensity was changed 60, 75, 90, and 105 Oe at 250 kHz, and the AMF frequency was changed 169, 213, 250, and 291 kHz at 105 Oe. The elevated equilibrium temperatures of 20 pieces of fibers increased from 46.8 °C to 56 °C and 46.7 °C to 61 °C with the increasing AMF intensity and frequency, respectively. The SLP also increased from 12.8 to 36.5 W/g.
Autors: Jinu Kim;Byung Mun Jung;Sang Bok Lee;Ki Hyeon Kim;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» IAA-Based High-Resolution ISAR Imaging With Small Rotational Angle
Abstract:
The Fourier transform-based range Doppler method is commonly used in an inverse synthetic aperture radar. Although it has achieved good success in most scenarios, its performance is determined by the rotational angle, and the cross-range resolution is extremely low in the case of a small rotational angle. In this letter, to improve the cross-range resolution, a novel cross-range compression scheme based on the iterative adaptive approach (IAA) is proposed. In addition to the standard IAA to achieve high resolution, the efficient IAA is introduced to suppress the sidelobes due to noise. Both the simulation and experimental results demonstrate that the proposed method has the advantages of parameter-free, high accuracy, and high efficiency.
Autors: Pengjiang Hu;Shiyou Xu;Wenzhen Wu;Biao Tian;Zengping Chen;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1978 - 1982
Publisher: IEEE
 
» ICA Based Semi-Blind Decoding Method for a Multicell Multiuser Massive MIMO Uplink System in Rician/Rayleigh Fading Channels
Abstract:
A massive multiple-input multiple-output (MIMO) system, which utilizes a large number of antennas at base stations to communicate with multiple user terminals each with a single antenna, is one of the most promising techniques for future wireless communications systems. A successful massive MIMO implementation relies on accurate channel estimation, which is typically performed through pilot sequences. However, the channel estimation performance or massive MIMO performance is limited by pilot contamination due to unavoidable reuse of pilot sequences from terminals in neighboring cells. In this paper, a semi-blind decoding method based on independent component analysis (ICA), channel energy levels, and reference bits is proposed. Specifically, the proposed decoding method uses ICA to separate and decode the received signals and to estimate the channels. The estimated channel energy is used to differentiate the in-cell signals and the neighboring cell signals, and reference bits are applied to identify a desired signal among signals within a cell. The analytical performance results of the proposed decoding method are derived. Numerical results show that the proposed semi-blind decoding method has better bit error rate performance and higher transmit efficiency than the traditional minimum mean-square error decoding method and the singular value decomposition-based decoding method.
Autors: Lei Shen;Yu-Dong Yao;Haiquan Wang;Huaxia Wang;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7501 - 7511
Publisher: IEEE
 
» ICSE Highlights
Abstract:
This issue’s column reports on papers from the 2017 International Conference on Software Engineering. Topics include context-based analytics, defect prediction, software development and energy consumption, continuous delivery, and continuous deployment.
Autors: Jeffrey C. Carver;Alexander Serebrenik;
Appeared in: IEEE Software
Publication date: Nov 2017, volume: 34, issue:6, pages: 18 - 20
Publisher: IEEE
 
» Identification of Dominant Low Frequency Oscillation Modes Based on Blind Source Separation
Abstract:
On-line monitoring and analysis of low frequency oscillation (LFO) are important for stability and security of a power system. This paper proposes a blind source separation (BSS) based method for LFO modal analysis of one-channel measured signal, which consists of a second-order blind identification (SOBI) algorithm and the Hilbert transform (HT) technique. This is the first time when a BSS technique is applied as a modal decomposition tool in this field. The proposed SOBI-HT based dominant mode identification method combines an iteration procedure with an identification procedure to determine the model order, and then identify dominant modes. The performance of the proposed method is evaluated on numerical simulation signals and a record of real data, verifying its effectiveness and accuracy.
Autors: A. Q. Zhang;L. L. Zhang;M. S. Li;Q. H. Wu;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4774 - 4782
Publisher: IEEE
 
» Identification of Modeling Boundaries for SSR Studies in Series Compensated Power Networks
Abstract:
Given large-scale power networks with series compensation, the study of subsynchronous resonance (SSR) is a significant challenge, in practice, due to the model complexity and computation burden. To tackle these difficulties, this paper proposes a method to reduce a large-scale system to an equivalent model using a metric called damping sensitivity index. The proposed metric can quantitatively identify the boundaries of the equivalent model that ensure the accurate studies of SSR and reduce the computation burdens greatly. The effectiveness of the method is verified by its application to the SSR investigation of the modified IEEE New England 10-machine 39-bus system and 16-machine 68-bus system. The equivalent models obtained by the proposed method are compared with the original systems in terms of driving point impedances, electrical damping, and transient torques. These results obtained show that the equivalent models from the proposed method can reproduce the SSR dynamics of the original systems with a much shorter computation time.
Autors: Wuhui Chen;Danhui Wang;Xiaorong Xie;Jin Ma;Tianshu Bi;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4851 - 4860
Publisher: IEEE
 
» IEEE Microwave Magazine Columnist Receives 2017 Apex Award [Awards]
Abstract:
Presents the recipient of the IEEE Microwave Magazine Columnist Receives 2017 Apex Award.
Autors: Alfy Riddle;
Appeared in: IEEE Microwave Magazine
Publication date: Nov 2017, volume: 18, issue:7, pages: 103 - 103
Publisher: IEEE
 
» IEEEXtreme?Engaging Student Branches [The Way Ahead]
Abstract:
Autors: J. Patrick Donohoe;
Appeared in: IEEE Potentials
Publication date: Nov 2017, volume: 36, issue:6, pages: 4 - 4
Publisher: IEEE
 
» Impact of Dynamic Interactions Introduced by the DFIGs on Power System Electromechanical Oscillation Modes
Abstract:
This paper derives the index of dynamic interactions (IDI), which is the sensitivity of a power system electromechanical oscillation mode (EOM) of concern to the dynamic interactions introduced by a grid-connected double-fed induction generator (DFIG). Based on the IDI, analysis is carried out with the following generally-applicable conclusions obtained: 1) Impact of dynamic interactions introduced by the DFIG increases when wind power penetration increases; 2) as long as the frequency response of an equivalent single DFIG model approximately matches the frequency response of a wind farm around the frequency of electromechanical oscillations of concern, this equivalent dynamic model of single DFIG can be used to represent the wind farm to examine the impact of wind farm on EOMs. Furthermore, an indicator of DFIG control (IDC) is derived for comparing the impact of terminal voltage control and reactive power control implemented by the DFIG. Main merit of the IDC is the computational simplicity without need to know dynamic model of the DFIG to indicate that either the terminal voltage control or the reactive power control is more beneficial to power system stability. An example multi-machine power system with grid-connected DFIGs is presented to demonstrate and validate the analysis and conclusions made in the paper.
Autors: Wenjuan Du;Xiao Chen;Hai Feng Wang;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4954 - 4967
Publisher: IEEE
 
» Impact of link parameters and channel correlation on the performance of FSO systems with the differential signaling technique: Errata
Abstract:
In our recently published paper (J. Opt. Commun. Netw., vol. 9, no. 2, p. 138, 2017), the following errors need to be corrected.
Autors: Mojtaba Mansour Abadi;Zabih Ghassemlooy;Stanislav Zvanovec;Manav R. Bhatnagar;Mohammad-Ali Khalighi;Yongle Wu;
Appeared in: IEEE/OSA Journal of Optical Communications and Networking
Publication date: Nov 2017, volume: 9, issue:11, pages: 1062 - 1063
Publisher: IEEE
 
» Impact of Trench Dimensions on the Device Performance of GaN Vertical Trench MOSFETs
Abstract:
In this letter, we have examined the impact of trench dimensions on the breakdown voltage and ON-resistance of trench MOSFETs fabricated on sapphire and bulk GaN substrates. Contrary to simulation studies, the breakdown voltage decreased with an increase in trench dimensions in devices fabricated on sapphire substrates. However, such breakdown voltage dependence with trench dimensions was not observed in devices fabricated on bulk GaN substrates of the same area. The observed trend on GaN on sapphire devices was associated with the equivalently reduced number of dislocations per device area. These results give an insight into how dislocations could affect breakdown voltage in power MOSFETs.
Autors: Chirag Gupta;Dong Ji;Silvia H. Chan;Anchal Agarwal;William Leach;Stacia Keller;Srabanti Chowdhury;Umesh K. Mishra;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1559 - 1562
Publisher: IEEE
 
» Impact of Tungsten Sputtering Condition on Magnetic and Transport Properties of Double-MgO Magnetic Tunneling Junction With CoFeB/W/CoFeB Free Layer
Abstract:
We investigated an effect of sputtering gas species (Ar, Kr, and Xe) for deposition of a W insertion layer in the CoFeB/W/CoFeB free layer on magnetic properties of the free layer and tunnel magnetoresistance (TMR) ratio of magnetic tunnel junctions (MTJs) stacks using the free layer annealed at 400 °C for 1 h. As the W insertion layer thickness increased, we found the degradation of perpendicular anisotropy and larger reduction of saturation magnetic moment per unit area in the free layer using Ar compared to those using Kr and Xe. We also found a smaller TMR ratio for the MTJ stack using Ar compared to those using Kr and Xe. Energy-dispersive X-ray spectrometry line analysis revealed more significant interdiffusion between W and CoFeB layers in the free layer using Ar than those using Kr and Xe, that could result in the smaller and perpendicular anisotropy in the free layer and smaller TMR ratio for the MTJ stack using Ar than those using Kr and Xe. We also investigated concentration of Ar, Kr, and Xe in W layers deposited using Ar, Kr, and Xe, respectively, by high-resolution Rutherford backscattering spectrometry, revealing that 0.2 at% Ar was detected in the W layer using Ar, while Kr and Xe were not detected in W layers using Kr and Xe. Such a difference in concentration of inert gas atoms in the W layer could be one possible reason for the difference about degree of interdiffusion between W and CoFeB layers.
Autors: H. Honjo;S. Ikeda;H. Sato;K. Nishioka;T. Watanabe;S. Miura;T. Nasuno;Y. Noguchi;M. Yasuhira;T. Tanigawa;H. Koike;H. Inoue;M. Muraguchi;M. Niwa;H. Ohno;T. Endoh;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Impacts of Retransmission Limit on Stability and Throughput Regions of S-ALOHA Systems
Abstract:
Limiting the number of retransmissions in practical random access systems such as S-ALOHA and IEEE 802.11 systems has been used, since it was often considered as a way of preventing the system from being congested, by dropping packets in retransmission or letting users know network congestion after the maximum of retransmissions. Therefore, it can be expected that the smaller the maximum of retransmissions is allowed, the smaller the backlog size gets with a higher packet dropping probability. This paper explores how such a retransmission limit alters the shape of the stability and throughput regions of S-ALOHA systems. To do this, we first consider an S-ALOHA system, where two users with infinite queue length have different packet arrival rate and retransmission probability, which is called asymmetric user. Then, we obtain those results of the systems with symmetric users.
Autors: Jun-Bae Seo;Hu Jin;Victor C. M. Leung;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10296 - 10306
Publisher: IEEE
 
» Imperfect-quantized-feedback-based beamforming for an FSO MISO system over Gamma-Gamma fading with pointing errors
Abstract:
In this paper, we propose an imperfect-quantized-feedback-based beamforming scheme for a generalized multiple-input single-output (MISO) free space optical (FSO) system over Gamma-Gamma fading channels with pointing error. It is well known that a feedback-based beamforming scheme aids channel adaptive signaling in wireless communication systems and provides large performance gain. If the feedback information is always decoded error free, then the beamforming technique reduces to a best transmit aperture selection scheme [termed error free optimal weighting scheme (EFOWS)]. However, due to a practically unguided environment, the feedback link is prone to error and leads to incorrect aperture selection, due to which diversity gain is lost. Therefore, a signal-to-noise ratio (SNR) adaptive error tolerant weighting (ETW) scheme is introduced and is optimized according to the SNR of the feedback link. In comparison to the considered arbitrarily fixed SNR-based ETW scheme, the proposed SNR adaptive ETW scheme provides significant performance gain (coding gain) almost equivalent to EFOWS. Closed-form expressions for the upper bound of the asymptotic average bit-error rate (BER) and the ergodic capacity of the proposed schemes are obtained with the help of order statistics. By minimizing the derived average BER, optimized transmit weights for the transmit apertures are achieved under erroneous feedback over Gamma-Gamma fading with pointing errors. Further, numerical results show that the proposed new error tolerant scheme outperforms the well-known repetition coding (referred to as the uniformly weighted scheme).
Autors: Ankit Garg;Manav R. Bhatnagar;Olivier Berder;Baptiste Vrigneau;
Appeared in: IEEE/OSA Journal of Optical Communications and Networking
Publication date: Nov 2017, volume: 9, issue:11, pages: 1005 - 1018
Publisher: IEEE
 
» Implementation of Radiating Aperture Field Distribution Using Tensorial Metasurfaces
Abstract:
This paper deals with the design of tensorial modulated metasurfaces able to implement a general radiating aperture field distribution. A new aperture synthesis approach is introduced, based on local holography and variable impedance modulation. In particular, it is shown that tensorial metasurfaces can be used to generate general radiating distribution (phase and amplitude). In addition, a step-by-step algorithm is presented. In order to validate the method, several solutions are presented at 20 GHz which implement aperture distributions able to radiate different beams with general polarization.
Autors: M. Teniou;H. Roussel;N. Capet;G.-P. Piau;M. Casaletti;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 5895 - 5907
Publisher: IEEE
 
» Implementation of the Single Hysteron Model in a Finite-Element Scheme
Abstract:
The single hysteron model is identified to reconstruct the magnetization processes of a grain-oriented electrical steel and it is implemented in a finite-element scheme. The model involves the Zeeman energy and the anisotropy energy of the material and an interaction field to take into account others terms, such as the magnetoelastic energy, the exchange energy, inclusions, and crystallographic discontinuities. The interaction field is evaluated experimentally using a round rotational single sheet tester, where a disk sample of the material is excited for several rotational magnetization processes. Details about the finite-element scheme, the computational time, and the memory allocations involved in the simulations are presented and discussed.
Autors: E. Cardelli;A. Faba;A. Laudani;G. M. Lozito;S. Quondam Antonio;F. Riganti Fulginei;A. Salvini;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Improper Signaling Versus Time-Sharing in the SISO Z-Interference Channel
Abstract:
It has recently been shown that improper signaling enlarges the rate region of the Gaussian single-antenna one-sided interference channel (Z-interference channel, ZIFC) under the assumptions that all input signals are Gaussian and that interference is treated as noise. It was pointed out that this result also holds if time-sharing between different operation points is allowed. However, the existing literature has considered the problem only for time-sharing under short-term average power constraints, i.e., if the average transmit powers are limited individually in each time slot. We consider the same problem under long-term average power constraints, where the transmit powers are limited only after averaging over all time slots. Interestingly, this modification changes the outcome of the study significantly: we can show that improper signaling can no longer bring any gains in this case.
Autors: Christoph Hellings;Wolfgang Utschick;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2432 - 2435
Publisher: IEEE
 
» Improved 3-D Magnetic Properties Measurement of Silicon Steel Laminations Based on a Novel Sensing Structure
Abstract:
The precise 3-D magnetic property measurement of the silicon steel is important to improve the efficiency and performance in electrical equipment, such as electrical machines and power transformers. An improved 3-D magnetic property measurement method of the silicon steel laminations is proposed by using a novel sensing structure with interconnecting multiple sensing coils covered on the surface of the cubic specimen. Based on the new coil structure with high precise coefficients from comprehensive calibration, the accurate relationship between B and H vectors is obtained and analyzed under alternating and 3-D rotating excitations with the feedback control method, especially when the laminated direction is considered. Consequently, the experimental data of magnetic properties with high precision can be obtained, which can provide important reference in designing and optimizing electrical equipment.
Autors: Yongjian Li;Xin Geng;Changgeng Zhang;Rongge Yan;Jianguo Zhu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Improved Broadband Matching Bound
Abstract:
In radio frequency systems where a load is driven by a source through a passive impedance matching circuit, the bandwidth over which match can be attained is limited. The Bode–Fano upper bound is often invoked to find this limit. We show that the bound is loose for some loads and, hence, cannot be attained by any network. We present a simple method to improve the bound and give conditions under which the improved bound is tight. The improved bound requires no additional assumptions or conditions beyond what is used for the Bode–Fano bound. Applications to analytical and numerical load models are demonstrated.
Autors: Ding Nie;Bertrand M. Hochwald;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 5878 - 5885
Publisher: IEEE
 
» Improved Depth-Assisted Error Concealment Algorithm for 3D Video Transmission
Abstract:
In this paper, a whole frame loss error concealment algorithm for three-dimensional video coding is proposed. The main concept of the proposed algorithm is to extrapolate the motion vectors for concealing a current error block by jointly considering the available motion vector and the depth information. In addition, the depth information is adopted to help the derivation of reference pixels for concealing errors in the case that suitable motion vectors cannot be obtained by the motion vector extrapolation process alone. Simulation results demonstrate that our proposed algorithm can achieve up to 0.52 dB PSNR, as well as subjective quality improvement, compared to previous work.
Autors: Pin-Cheng Huang;Jie-Ru Lin;Gwo-Long Li;Kuang-Han Tai;Mei-Juan Chen;
Appeared in: IEEE Transactions on Multimedia
Publication date: Nov 2017, volume: 19, issue:11, pages: 2625 - 2632
Publisher: IEEE
 
» Improved Efficiency of Tapered Magnetic Flux Concentrators With Double-Layer Architecture
Abstract:
Being able to increase the sensitivity of magnetoresistive sensors, by orders of magnitude, provides a route toward challenging detection levels, and opens the way for new applications. This paper describes a novel architecture of magnetic flux concentrators to achieve an improved guiding efficiency, combining materials with different magnetic properties, and a vertical tapering. The novelty consists in the concentration of the magnetic flux kept by the entire structure in a reduced cross-sectional area within the vicinity of the spinvalve sensor. Depending on the configuration of the double-layer magnetic flux concentrators, average sensitivity gains of and were obtained. This enhanced guiding efficiency also reduced the impact of a misalignment between the device sensing direction and the applied magnetic field, since the device performance is not compromised until a misalignment angle °. This further stabilization may arise from the vertical tapering of the magnetic flux concentrator, being consistent with 2-D finite-element simulations.
Autors: J. Valadeiro;D. C. Leitao;S. Cardoso;P. P. Freitas;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Improved Figure-of-Eight Coil for Transcranial Magnetic Stimulation Using Magnetic Resonant Coupling
Abstract:
This paper proposes an improved figure-of-eight coil for transcranial magnetic stimulation (TMS) by using the magnetic resonant coupling (MRC) effect, aiming to improve the treatment effect for psychiatric disorders. The proposed MRC-based figure-of-eight coil consists of two reverse-winding resonance coils, which embraces two series-connected source coils, respectively. Different from conventional figure-of-eight coils, the proposed topology can produce the resonant electromagnetic field to accumulate the stimulation energy. In such ways, the improved TMS system can effectively enhance the stimulation focality and depth while significantly reducing the requirement of the power supply, thus improving the safety as well as facilitating the miniaturization and portability. Last, this paper gives the simulated and experimental results to verify the theoretical analysis, which can further illustrate the feasibility of the proposed MRC-based figure-of-eight coil for TMS systems.
Autors: Zhen Zhang;Wenjie Ai;Bin Deng;Wei Han;Jiang Wang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Improved High-Frequency Rotating Magnetic Properties Tester for Nanocrystalline Soft Magnetic Material
Abstract:
In order to study and analyze the rotating magnetic properties for nanocrystalline material, an improved 2-D high-frequency magnetic properties tester with step-shaped excitation windings and composite sensing structure is designed and modeled. Magnetic concentration and core poles optimization are performed in 2-D tester construction, which can generate relatively uniform and strong magnetic field in the testing area. By using the composite sensing structure of sensing coil combined with needle probe method, and signals can accurately be detected. Meanwhile, feedback control algorithm and harmonic compensation are established to obtain the desired magnetization curves and improve the measurement precision.
Autors: Yongjian Li;Qing Zhao;Lixiang Wang;Changgeng Zhang;Rongge Yan;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Improved ISAC Algorithm to Retrieve Atmospheric Parameters From HyTES Hyperspectral Images Using Gaussian Mixture Model and Error Ellipse
Abstract:
In-scene atmospheric correction (ISAC) is a procedure that accounts for atmospheric effects by direct use of the hyperspectral radiance data without recourse to ancillary meteorological data. This letter aims to improve the accuracy of the ISAC algorithm. In the ISAC method after calculating brightness temperature, the computed radiance and measured radiance at the sensor are plotted on a graph in each band. Then, to estimate atmospheric parameters, the straight line is fit to the upper boundary of the plot. One of the issues in ISAC is to find an optimal upper boundary of data. The main innovation of this letter is the use of Gaussian mixture model (GMM) and error ellipse to find the optimal upper boundary of data and fit the line to it. In the line fitting process, first, a GMM with the optimum class number derived by Akaike information criterion (AIC) is implemented on thermal hyperspectral data and then, the optimal upper boundary is selected for each class and a straight line is fit to it. Finally, the desired parameters are obtained with weighted linear combination of the results from all classes. For quality assessment, the results were compared with atmospheric products of Hyperspectral Thermal Emission Spectrometer sensor and atmospheric parameters that were obtained from traditional ISAC. Root-mean-square errors for atmospheric transmittance obtained from GMM for bands 9.8 and are 0.0008 and 0.0106 and those for upwelling atmospheric radiance are 0.675 and 0.0265, respectively.
Autors: Faeze Soleimani vosta kolaei;Mehdi Akhoondzadeh;Hamid Ghanbari;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2087 - 2091
Publisher: IEEE
 
» Improved Message Passing Algorithms for Sparse Code Multiple Access
Abstract:
Sparse code multiple access (SCMA) is one of the nonorthogonal multiple access techniques for the 5G system. SCMA can provide different levels of overloading to meet the diverse traffic connectivity requirements. However, its relatively high computational complexity of multiuser detection is still a significant concern for practical implementation, even when the sparse structure has already been employed. In this paper, a design framework for an improved SCMA multiuser detector is proposed based on the message passing algorithm (MPA). As the primary SCMA detector, two aspects of MPA are simplified and optimized. First, we introduce a lookup table (LUT) scheme to reduce the computational complexity of the operation in the MPA. In contrast to the extensive Jacobian approximation, the proposed LUT method can guarantee the stable convergence of the MPA for SCMA. Second, a series of novel scheduling schemes are proposed to speed up the convergence. A single scheduling MPA (SS-MPA) method is given to enhance the convergence performance of MPA, where the soft messages in the function nodes and variable nodes are serially calculated and synchronously updated. To further improve the throughput of the MPA, a multiple scheduling MPA (MS-MPA) is proposed. In this method, multiple detectors are used to calculate in parallel and update the node messages by different orders. Since the scheduling strategies of message update are optimized, both the SS-MPA and MS-MPA can converge more quickly than the conventional MPA. Theoretical analyses and simulation results regarding the error performance and convergence properties of the above schemes are included.
Autors: Jincheng Dai;Kai Niu;Chao Dong;Jiaru Lin;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9986 - 9999
Publisher: IEEE
 
» Improved Optoelectronic Performance of High-Voltage Ultraviolet Light-Emitting Diodes Through Electrode Designs
Abstract:
High-efficiency high-voltage ultraviolet light-emitting diodes (HV-UVLEDs) consisting of a microcells array with an area of were designed and fabricated via the electrode pattern and interconnect technique. Polymer material was used to fill trench with planarization, and interconnection technology was used for metal layer connection to address wiring defect issue. In comparison with the conventional lateral UV-LED (C-UVLED), which had 33.6% and 34.7% enhancement in the light output power and wall-plug efficiency (at 1.5 W) of the HV-UVLEDs. A 56% improvement in the external quantum efficiency droop behavior was achieved for the HV-UVLEDs when compared with that of C-UVLED. This improvement can be attributed to superior current spreading in the HV-UVLED due to its smaller microcells, which increases light-emission efficiency overall.
Autors: Ching-Ho Tien;Chen-Hao Kuo;Dong-Sing Wuu;Ray-Hua Horng;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4526 - 4531
Publisher: IEEE
 
» Improved Range Analysis in Fixed-Point Polynomial Data-Path
Abstract:
In range analysis (RA), suitable integer bit-widths are assigned to the variables so that no overflow occurs. Although the accuracy in RA rather than error analysis has more impact on hardware cost and efficiency, there are few works that offer new approaches to improve RA. Arithmetic functions, mostly represented by polynomials, are normally suitable for both optimization and verification purposes. In this paper, a safe and more accurate RA of feed-forward fixed-point polynomial data-flow graphs is proposed. The method employs particular features of RA and maps it to a specific class of polynomial optimization problems. The proposed method provides tighter ranges while taking less runtime in comparison with satisfiability-modulo theory-based method. Furthermore, the improved ranges lead to enhance the area and delay efficiency more than 50% and 24%, respectively, when the circuits are implementing the functions in comparison with the state-of-the-art techniques.
Autors: Mahdieh Grailoo;Bijan Alizadeh;Behjat Forouzandeh;
Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Publication date: Nov 2017, volume: 36, issue:11, pages: 1925 - 1929
Publisher: IEEE
 
» Improved Successive-Cancellation Decoding of Polar Codes Based on Recursive Syndrome Decomposition
Abstract:
In this letter an improved method for the successive-cancellation decoding of polar codes is proposed. To avoid computations associated with redundant tree-traversals and syndrome calculations, recursive properties of polar codes are newly exploited in the proposed algorithm. Instead of computing a syndrome vector at every node, some syndrome vectors are directly obtained by recursively decomposing the syndrome vector computed previously. Furthermore, a modified syndrome check rule is proposed to prune unnecessary sub-trees efficiently. Compared with the latest pruning method, the proposed method reduces the latency by 23% for a (2048, 1024) polar code without sacrificing the error-correcting performance.
Autors: Jaejoon Choi;In-Cheol Park;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2344 - 2347
Publisher: IEEE
 
» Improved Synchrophasor Models for Power System Dynamic Stability Evaluation Based on IEEE C37.118.1 Reference Architecture
Abstract:
Synchrophasors are an emerging power system wide-area dynamic performance monitoring and control technology. The IEEE standard C37.118.1 outlines specifications for the construction of synchrophasor units, in which two reference synchrophasor models are proposed for protection (P-type) and measurement (M-type) purposes. This paper develops improved synchrophasor models for power system dynamic stability/performance evaluation based on the reference architecture proposed in the IEEE standard C37.118.1, considering frequency error (FE) and the total vector error (TVE) as the main performance indices. The quadrature demodulation filters are designed explicitly considering the impact of harmonic distortion and out-of-band interference, and thus optimized quadrature demodulation filters improve estimation performance during adverse conditions. Furthermore, a special emphasis is placed on the input low-pass filter to attenuate high-frequency components above the Nyquist rate. The improved synchrophasor models are rigorously tested to ensure compliance with performance requirements stipulated in the IEEE standard. Results show that improved synchrophasor models significantly enhance the FE while ensuring compliance requirements for the TVE.
Autors: Chathura Thilakarathne;Lasantha Meegahapola;Nuwantha Fernando;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2937 - 2947
Publisher: IEEE
 
» Improvement in Offaxis Neuromuscular Control Under Slippery Conditions Following Six-Week Pivoting Leg Neuromuscular Training
Abstract:
Knee injuries are usually associated with offaxis loadings in the transverse and frontal planes. Thus, improvement of lower limb offaxis neuromuscular control is important in knee injury prevention and post-injury rehabilitation. The goal of this paper was to investigate the effects of six-week pivoting offaxis intensity adjustable neuromuscular control training (POINT) using a custom-made offaxis elliptical trainer on lower limb offaxis neuromuscular control performance in trained and untrained functional tasks under slippery conditions. Twenty-six subjects participated in 18 sessions of POINT (three sessions per week for six weeks) and 25 subjects served as controls who did a regular workout. Offaxis neuromuscular control performance measures in terms of pivoting instability, sliding instability, and time-to-peak offaxis EMG entropy were evaluated on both groups under slippery conditions including a trained free pivoting task and untrained free sliding task and free pivoting and sliding task. Compared with the control group, the training group significantly decreased pivoting instability and the time-to-peak offaxis EMG entropy in lower limb muscles, indicating improvement in offaxis neuromuscular control performance. Furthermore, the training group showed reduced pivoting instability and sliding instability during the untrained free pivoting and sliding task. This paper may help us develop more focused and effective offaxis training programs to reduce knee injuries associated with offaxis loadings.
Autors: Song Joo Lee;Yupeng Ren;Joel M. Press;Jungwha Lee;Li-Qun Zhang;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Nov 2017, volume: 25, issue:11, pages: 2084 - 2093
Publisher: IEEE
 
» Improvement of a Pansharpening Method Taking Into Account Haze
Abstract:
Pansharpening is an important technique used to generate high-quality high-spatial-resolution multispectral (MS) bands by fusing low-spatial-resolution MS bands and a panchromatic (PAN) band obtained by the same sensor. A PAN-modulation (PM)-based pansharpening method taking account of haze, which is referred as Haze- and Ratio- based (HR) method, has been demonstrated to yield good performances, indicating that the impact of haze should be considered in PM-based methods. It is obvious that the haze values used in the HR fusion influence the spectral vectors of fused pixels, thus affect the spectral distortion of fused images. In order to reach stable and good performances of the HR method, the determination of the optimal haze values is discussed in this study. First, six approaches for haze values determination, which are variations of the histogram minimal approach and the darkest pixel approach employed by the image-based dark-object subtraction method for atmospheric correction of remote-sensed images, are compared. Then, an improved approach for haze values determination is proposed. The proposed approach is proved to be effective for improving the performance of the HR method. This is very important for the employment of the HR method in practical applications and by more researchers.
Autors: Hui Li;Linhai Jing;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 5039 - 5055
Publisher: IEEE
 

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