Electrical and Electronics Engineering publications abstract of: 11-2017 sorted by title, page: 13

» Medium Stack Optimization for Microwave-Assisted Magnetic Recording
Abstract:
In this paper, we present systematic micromagnetic modeling investigation on recording process of segmented thin-film media with circularly polarized magnetic field at microwave frequencies. This paper provides insightful understanding about the segmented medium stack design in microwave-assisted magnetic recording (MAMR) by exploring the impact of signal-to-noise (SNR) ratio and recording track width. By utilizing segmentation of grains with exchange breaking layers, the ac magnetic field generated from spin torque oscillator can be best exploited. Via optimized medium stack design, MAMR is able to achieve both high SNR and areal density gain with the proposed notched-structure medium (top and bottom segments have the strongest crystalline anisotropy) compared with conventional graded medium (with gradually increasing anisotropy from top to bottom). By tuning crystalline anisotropy strength in top and bottom segment, we studied the MAMR behavior of SNR and track width under different ac frequencies. This provides a novel view for future segmented media design.
Autors: Xiaoyu Bai;Jian-Gang Zhu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Medium-Resolution Soil Moisture Retrieval Using the Bayesian Merging Method
Abstract:
The National Aeronautics and Space Administration’s Soil Moisture Active Passive (SMAP) mission, launched in January 2015, was designed to provide a global soil moisture product at medium resolution (~9 km), by combining observations from its radar and radiometer. Several downscaling methods have been proposed by the SMAP team for this purpose. This paper evaluates another candidate downscaling method, namely, the Bayesian merging approach. While this has been tested using a synthetic data set across the USA, it is imperative that it can also be tested using the experimental data for a comprehensive range of land surface conditions (i.e., in different hydro-climatic regions) prior to a global application. Consequently, this paper applies this method using the data collected from SMAP experiments field campaigns in south-eastern Australia that closely simulated the SMAP data stream for a single SMAP radiometer pixel over a three-week interval. The method studied here differs from the linear downscaling methods of the SMAP mission, in that it uses a nonlinear method based on Bayes’ theorem. The medium-resolution soil moisture product is obtained using background soil moisture estimates that are updated according to the difference between the observed and predicted brightness temperatures and backscatter coefficients, relating the high- and low-resolution data. Results were assessed against a reference soil moisture map derived from high-resolution airborne radiometer observations. The root-mean-square-error and for the Bayesian merging method were found to be 0.02 cm3/cm3 and 0.55, respectively, at 9-km resolution, being similar to the SMAP’s “optional” downscaling method.
Autors: Xiaoling Wu;Jeffrey P. Walker;Christoph Rüdiger;Rocco Panciera;Ying Gao;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6482 - 6493
Publisher: IEEE
 
» Meetings calendar
Abstract:
Provides a listing of future meetings.
Autors: Davide Fabiani;
Appeared in: IEEE Electrical Insulation Magazine
Publication date: Nov 2017, volume: 33, issue:6, pages: 61 - 63
Publisher: IEEE
 
» Memory-in-Pixel Circuit for Low-Power Liquid Crystal Displays Comprising Oxide Thin-Film Transistors
Abstract:
We propose a new memory-in-pixel (MIP) circuit with only oxide thin-film transistors (Ox-TFTs) for a low-power liquid crystal display with flicker-free feature. The proposed MIP circuit is composed of two new memory circuit units comprising two Ox-TFTs and a capacitor. The proposed memory circuit can modulate the threshold voltage via a simple driving scheme. When the threshold voltage is shifted properly, Ox-TFTs maintain the ON or OFF state by virtue of their extra low leakage current, which enables the MIP operation. By applying the black or white voltage to the pixel directly, flicker can be eliminated. We fabricated the MIP circuit and investigated the circuit performance depending on the capacitance and TFT sizes. Finally, we verified the feasibility of the proposed MIP circuit for low power operation.
Autors: Seung-Hyuck Lee;Byung-Chang Yu;Hoon-Ju Chung;Seung-Woo Lee;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1551 - 1554
Publisher: IEEE
 
» Merge Mode for Deformable Block Motion Information Derivation
Abstract:
Motion estimation (ME) plays an important role in most video coding standards since it can improve the coding performance significantly. Block matching ME (BMME) based on translation motion model is employed in both H.264/Advanced Video Coding and High Efficiency Video Coding (HEVC), which assumes that all the pixels in a block undergo the same motion. However, BMME cannot represent the complex motion accurately, such as rotation, zoom, and deformation motion. To resolve the problem, a merge mode for deformable block motion information derivation is proposed, which considers bilinear interpolation model, six-parameter affine model, and four-parameter affine model simultaneously. The sum of absolute transformed differences criterion is used to select the best model for a block. In the proposed merge mode, the motion information of the current block is derived from the motion information of its neighbors. It does not need to perform ME and transmit motion parameters. The proposed merge mode is integrated into HEVC test model (HM) 14.0. The simulation results show that compared with HM14.0, the proposed merge mode can bring 1.3%, 1.7%, and 2.7% Bjøntegaard delta (BD) bitrate savings on average for test sequences of HEVC, and 11.0%, 15.2%, and 17.4% BD bitrate savings for deformation sequences in random access main, low-delay B main, and low-delay P main test conditions, respectively, while the increased encoding and decoding complexities are moderate.
Autors: Na Zhang;Xiaopeng Fan;Debin Zhao;Wen Gao;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Nov 2017, volume: 27, issue:11, pages: 2437 - 2449
Publisher: IEEE
 
» meSchup: A Platform for Programming Interconnected Smart Things
Abstract:
In a future where hundreds of smart networked devices will be embedded in our everyday environments, the question of how to program the world around us arises. An abstraction layer and web-based integrated development environment can interweave available smart things’ capabilities into a collective orchestration of smart behavior.
Autors: Thomas Kubitza;Albrecht Schmidt;
Appeared in: Computer
Publication date: Nov 2017, volume: 50, issue:11, pages: 38 - 49
Publisher: IEEE
 
» Metal Sulfates Enhanced Plasma Oxidization of Diesel Particulate Matter
Abstract:
The activities for nonthermal plasma-induced oxidation of diesel particulate matter (DPM) with various metal sulfates were investigated. It was found that the metal sulfates, MgSO4, K2SO4, and CaSO42H2O, enhanced the energy yield of DPM oxidation while other sulfates, Na2SO4, Fe2(SO4)3, and Al2(SO4)8H2O, did not affect the energy yield. The addition of water vapor caused a promotion of DPM oxidation regardless of a metal sulfate was presented. The effect of temperature and sulfate adding amount was also investigated. The metal sulfates enhanced DPM oxidation is possibly due to the adsorption of O atoms onto the sulfates. The positive effects of H2O might be thought of as due to the formation of reactive OH radicals and the promotion of the hydrolysis of the oxygen-containing compounds on DPM surface.
Autors: Shuiliang Yao;Xing Shen;Haiquan Lu;Danwei Ni;Xiujuan Tang;Zuliang Wu;Jingyi Han;Xuming Zhang;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 2984 - 2987
Publisher: IEEE
 
» Method for Simulating Dose Reduction in Digital Breast Tomosynthesis
Abstract:
This paper proposes a new method of simulating dose reduction in digital breast tomosynthesis, starting from a clinical image acquired with a standard radiation dose. It considers both signal-dependent quantum and signal-independent electronic noise. Furthermore, the method accounts for pixel crosstalk, which causes the noise to be frequency-dependent, thus increasing the simulation accuracy. For an objective assessment, simulated and real images were compared in terms of noise standard deviation, signal-to-noise ratio (SNR) and normalized noise power spectrum (NNPS). A two-alternative forced-choice (2-AFC) study investigated the similarity between the noise strength of low-dose simulated and real images. Six experienced medical physics specialists participated on the study, with a total of 2 160 readings. Objective assessment showed no relevant trends with the simulated noise. The relative error in the standard deviation of the simulated noise was less than 2% for every projection angle. The relative error of the SNR was less than 1.5%, and the NNPS of the simulated images had errors less than 2.5%. The 2-AFC human observer experiment yielded no statistically significant difference (=0.84) in the perceived noise strength between simulated and real images. Furthermore, the observer study also allowed the estimation of a dose difference at which the observer perceived a just-noticeable difference (JND) in noise levels. The estimated JND value indicated that a change of 17% in the current-time product was sufficient to cause a noticeable difference in noise levels. The observed high accuracy, along with the flexible calibration, make this method an attractive tool for clinical image-based simulations of dose reduction.
Autors: Lucas R. Borges;Igor Guerrero;Predrag R. Bakic;Alessandro Foi;Andrew D. A. Maidment;Marcelo A. C. Vieira;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Nov 2017, volume: 36, issue:11, pages: 2331 - 2342
Publisher: IEEE
 
» Metrics and Quantification of Operational and Infrastructure Resilience in Power Systems
Abstract:
Resilience to high impact low probability events is becoming of growing concern, for instance to address the impacts of extreme weather on critical infrastructures worldwide. However, there is, as yet, no clear methodology or set of metrics to quantify resilience in the context of power systems and in terms of both operational and infrastructure integrity. In this paper, the resilience “trapezoid” is therefore introduced which extends the resilience “triangle” that is traditionally used in existing studies, in order to consider the different phases that a power system may experience during an extreme event. The resilience trapezoid is then quantified using time-dependent resilience metrics that are specifically introduced to help capture the critical system degradation and recovery features associated to the trapezoid for different temporal phases of an event. Further, we introduce the concepts of operational resilience and infrastructure resilience to gain additional insights in the system response. Different structural and operational resilience enhancement strategies are then analyzed using the proposed assessment framework, considering single and multiple severe windstorm events that hit the 29-bus Great Britain transmission network test case. The results clearly highlight the capability of the proposed framework and metrics to quantify power system resilience and relevant enhancement strategies.
Autors: Mathaios Panteli;Pierluigi Mancarella;Dimitris N. Trakas;Elias Kyriakides;Nikos D. Hatziargyriou;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4732 - 4742
Publisher: IEEE
 
» mHealth Dipstick Analyzer for Monitoring of Pregnancy Complications
Abstract:
Dipstick-based urinalysis is routinely used for the detection of early signs of such pregnancy complications, as preeclampsia and gestational diabetes. Usually it is done in doctor’s office using an automatic dipstick analyzer. Here, we present a novel smartphone-based colorimeter and demonstrate its application to the measurements of glucose and protein concentrations in biological samples. The key innovations of our approach was to combine powerful image processing encoded into a mobile phone application with a low cost 3-D printed sample holder that allowed to control lighting conditions and significantly improved sensitivity. Different solutions with protein and glucose concentrations ranging from 0 to 2000 mg/dL were prepared and analyzed using our system. The detection limit for glucose was 40 mg/dL and for protein −6mg/dL The smartphone-based colorimeter always correctly classified the corresponding reagent strip pads, what confirms that it can be used as a low cost alternative for commercial dipstick analyzers.
Autors: Karthik Raj Konnaiyan;Surya Cheemalapati;Michael Gubanov;Anna Pyayt;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7311 - 7316
Publisher: IEEE
 
» Micro-Focused Pulse Laser-Induced Propagating Spin Waves in Permalloy Films With Different Thicknesses
Abstract:
Propagating spin waves excited by a micro-focused ultra-short pulse laser were investigated in Permalloy films with the thicknesses of 20, 50, and 100 nm by means of an all-optical space-and-time-resolved magneto-optical Kerr effect. Although various perpendicular standing spin-wave modes were excited, the propagating magneto-static surface spin wave was clearly detected in each film, where the group velocities of approximately 4, 8, and 12 km/s and the propagation lengths of 3.8, 6.6, and 13 for the 20, 50, and 100 nm-thick films, respectively, were evaluated. The evaluated group velocities were consistent with the theoretical values, whereas the propagation lengths were smaller than the theoretical values with the Gilbert damping constant of 0.008.
Autors: Akira Kamimaki;Satoshi Iihama;Yuta Sasaki;Yasuo Ando;Shigemi Mizukami;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Microbubble Axial Localization Errors in Ultrasound Super-Resolution Imaging
Abstract:
Acoustic super-resolution imaging has allowed the visualization of microvascular structure and flow beyond the diffraction limit using standard clinical ultrasound systems through the localization of many spatially isolated microbubble signals. The determination of each microbubble position is typically performed by calculating the centroid, finding a local maximum, or finding the peak of a 2-D Gaussian function fit to the signal. However, the backscattered signal from a microbubble depends not only on diffraction characteristics of the waveform, but also on the microbubble behavior in the acoustic field. Here, we propose a new axial localization method by identifying the onset of the backscattered signal. We compare the accuracy of localization methods using in vitro experiments performed at 7-cm depth and 2.3-MHz center frequency. We corroborate these findings with simulation results based on the Marmottant model. We show experimentally and in simulations that detecting the onset of the returning signal provides considerably increased accuracy for super-resolution. Resulting experimental cross-sectional profiles in super-resolution images demonstrate at least 5.8 times improvement in contrast ratio and more than 1.8 times reduction in spatial spread (provided by 90% of the localizations) for the onset method over centroiding, peak detection, and 2-D Gaussian fitting methods. Simulations estimate that these latter methods could create errors in relative bubble positions as high as at these experimental settings, while the onset method reduced the interquartile range of these errors by a factor of over 2.2. Detecting the signal onset is, therefore, expected to considerably improve the accuracy of super-resolution.
Autors: Kirsten Christensen-Jeffries;Sevan Harput;Jemma Brown;Peter N. T. Wells;Paul Aljabar;Christopher Dunsby;Meng-Xing Tang;Robert J. Eckersley;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Nov 2017, volume: 64, issue:11, pages: 1644 - 1654
Publisher: IEEE
 
» Microgrid Modular Design for Tribal Healthcare Facilities: Kayenta Health Center PV System Case Study
Abstract:
This paper describes an experimental process and detailed information related to a 100-KW photovoltaic (PV) system case study at the Kayenta Health Center, which is located in the Navajo Nation. Information about the solar irradiance on site, the PV system performance, the power quality at the facility, and observation of the related equipment is gathered. Experimental data validate the theoretical data available for the zone, the facility, the systems, and the equipment. Detailed study of an existing PV system at the Navajo Nation combined with modeling and simulation will lead to a good industrial pilot project from implementation and practical perspective of the microgrid in existing tribal health care facilities. A modified configuration of the existing power system is presented. The configuration provides guidance for the redesign of existing healthcare facilities around the microgrid concept. Since the Kayenta Health Center is representative of the average healthcare facility in the Navajo Nation, this guidance will be useful for the improvement of the power system of many tribal healthcare facilities. This in turn will improve the quality of the healthcare service and will benefit the living conditions of a significant tribal population.
Autors: Samuel Vega Cotto;Wei-Jen Lee;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5121 - 5129
Publisher: IEEE
 
» Micromagnetic Analysis of Statistical Switching in Perpendicular STT-MRAM With Interfacial Dzyaloshinskii–Moriya Interaction
Abstract:
The technological implementation of STT-magnetic random-access memory (MRAM) in real devices needs a complete description of the statistical switching behavior at room temperature. In this paper, we investigate, by means of a full micromagnetic model, the effect of the interfacial Dzyaloshinskii–Moriya interaction (IDMI) on the critical current density and probability density function (PDF) of the switching time in perpendicular STT-MRAMs. We show that for large enough values of the symmetric exchange interaction, the negative effect of the IDMI on the critical current is strongly reduced. In addition, a comprehensive analysis of the four main statistical moments (mean, standard deviation, skewness, and kurtosis) points out that to fit the switching time PDF in order to maintain a quadratic error at least one order of magnitude smaller than skew normal PDF, a Pearson type IV PDF has to be used also in presence of the IDMI.
Autors: G. Siracusano;R. Tomasello;V. Puliafito;A. Giordano;B. Azzerboni;A. La Corte;P. Burrascano;G. Finocchio;M. Carpentieri;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Micromagnetic Model Analysis of Various Spin-Torque Oscillators With Write Head for Microwave-Assisted Magnetic Recording
Abstract:
A micromagnetic model analysis was carried out considering two types of write heads and three types of spin-torque oscillators (STOs). For write heads, we considered a small-sized head to reduce calculation time and a large-sized head with dimensions close to commercial heads. For STOs, we used a double-layered STO with reflection spin torque, a double-layered STO with transmission spin torque, and a tri-layered STO with two spin injection layers. We also carried out micromagnetic simulations of the STOs without the write heads (isolated STO) to compare the oscillation states. It was found that, compared with isolated STOs in a uniform applied field, a larger applied field was necessary for STOs integrated into a write head. This result shows that the write head should be designed to generate a large, well-shaped gap field to ensure stable STO oscillation.
Autors: Yasushi Kanai;Ryo Itagaki;Simon J. Greaves;Hiroaki Muraoka;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Micromagnetic Simulation of Microwave-Assisted Magnetization Switching Process for Granular Films
Abstract:
Microwave-assisted magnetization switching (MAS) processes for granular films were demonstrated by time integration of the Landau–Lifshitz–Gilbert equation. At low microwave frequencies, hysteresis loops become narrower, and at higher frequencies, an extra step occurs in the curves. In the case when the extra step occurs, saturation field increases to be comparable to that for non-MAS case, although switching field decreases. The occurrence of the extra step possibly originates from “unstable switching process” predicted by Bertotti et al., and the magnetization contour maps indicated large un-switched agglomerates remains when MAS proceeds through the unstable switching process. The unstable switching processes are also observed even when dc incident angles are large.
Autors: Terumitsu Tanaka;Yukio Nozaki;Kimihide Matsuyama;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Micromagnetic Simulations for Coercivity Improvement Through Nano-Structuring of Rare-Earth-Free L10-FeNi Magnets
Abstract:
In this paper, we investigate the potential of tetragonal L10-ordered FeNi as the candidate phase for rare-earth-free permanent magnets considering anisotropy values from recently synthesized, partially ordered FeNi thin films. In particular, we estimate the maximum energy product (BH)max of L10-FeNi nanostructures using micromagnetic simulations. The maximum energy product is limited due to the small coercive field of partially ordered L10-FeNi. Nano-structured magnets consisting of 128 equi-axed, platelet-like, and columnar-shaped grains show a theoretical maximum energy product of 228, 208, and 252 kJm, respectively.
Autors: Alexander Kovacs;Johann Fischbacher;Harald Oezelt;Thomas Schrefl;Andreas Kaidatzis;Ruslan Salikhov;Michael Farle;George Giannopoulos;Dimitris Niarchos;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Micromagnetic Simulations of Magnetization Spatial Distribution in Ultrathin Cobalt Layers With Gradient Magnetic Anisotropy
Abstract:
Spatial distribution of magnetization in an ultrathin ferromagnetic Co layer with a lateral gradient of magnetic anisotropy, while approaching spin reorientation transition (SRT) (from perpendicular to in-plane magnetization alignment), has been investigated by means of micromagnetic simulations in the 2-D mode, using OOMMF software. The geometry of the out-of-plane-magnetized domains (parallel stripes, labyrinth, and bubbles) has been found to be dependent on both the initial distribution of magnetization and the direction of the applied magnetic field. A fast decrease in the domain size has been observed while moving toward SRT. In the experiment, Pt/Co/Pt layers with initial in-plane magnetization orientation have been irreversibly modified by femtosecond laser pulses. In the irradiated spot, rings with induced perpendicular magnetic anisotropy have been formed, resulting in an appearance of several local SRTs. Magnetic domain structure in the SRT regions has been visualized using magnetic force microscopy. The experimental observations are qualitatively explained by the results of the micromagnetic simulations.
Autors: Marek Kisielewski;Jan Kisielewski;Iosif Sveklo;Andrzej Wawro;A. Maziewski;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Micromagnetic Studies at Finite Temperature on FePt–C Granular Films
Abstract:
A new micromagnetic method using the hybrid Monte Carlo (HMC) algorithm has been developed, and the magnetic properties at finite temperature can be simulated. In this paper, the HMC micromagnetics are applied on the polycrystalline FePt–C granular films for heat-assisted magnetic recording, where the significant parameters such as the temperature-dependent saturation magnetization (T) are measured by experiments. The Voronoi polycrystalline microstructure is built upon a regular mesh of micromagnetic cells. The magnetization (M–H) loops below the Curie temperature are calculated; they agree well with experiments at 300, 400, 500, and 600 K, respectively, which have confirmed the validity of the HMC micromagnetic method. Besides, the M–H loop at 700 K, which currently cannot be measured by experiments, can also be simulated using the HMC algorithm, which shows superparamagnetic properties.
Autors: Junjie Song;J. Wang;Dan Wei;Y. K. Takahashi;K. Hono;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Micromagnetic Studies of Time-Dependent Coercivity
Abstract:
This paper has studied the time-dependent coercivity in both the constant-field model and changing-field model, based on a new micromagnetic method at finite temperature using the hybrid Monte Carlo (HMC) algorithm. By comparing the simulated time-dependent coercivity with Sharrock’s law, the scaling relationship between the fictitious simulation time in the Hamilton equations in the HMC micromagnetics and the real time t is derived, and the simulation time in a trajectory () is found to be close to 1 ns in the real-time scale. Furthermore, we have studied the effects of the magnetic anisotropy types on the parameter in Sharrock’s law, and it is found that the cubic anisotropy model exhibits a larger value than the uniaxial anisotropy model. Our simulation results agree well with the experiments and the results from other simulation methods under certain circumstances.
Autors: Jingyue Miao;Dan Wei;Chuan Liu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Microstructural Analysis During the Step-Cooling Annealing of Iron-Rich Sm(Co0.65Fe0.26Cu0.07Zr0.02)7.8 Anisotropic Sintered Magnets
Abstract:
Microstructural analysis during the step-cooling procedure of iron-rich Sm(Co0.65Fe0.26Cu0.07Zr0.02)7.8 anisotropic sintered magnets was investigated systematically. The sintered magnet exhibits the maximum energy product of about 32 MGOe together with a remanence of about 11.5 kGs. It is found that the cellular structure has formed at the stage of isothermal annealing (heat treating at 1103 K for 20 h). Moreover, the average cell size of the 2:17 cell phase in magnets decreases from ~150 to ~105 nm, and the density of the lamella phase increases from ~0.03 to ~0.05 1/nm during the step-cooling procedure. It is also found that the Cu concentration is homogeneous in the specimen quenched at a temperature of 1103 K and then becomes nonuniform, especially enriched in the cell boundaries during the step cooling to 873 K. Interestingly, the typical twining structure along the [010] zone of the main phase exists in the specimen quenched at 873 K. Furthermore, it is inferred that the magnetization mechanism of the specimens transforms from the nucleation-dominated type to the coexisting type of pinning and nucleation effect during the step-cooling procedure.
Autors: Kuikui Song;Yikun Fang;Wei Sun;Hongsheng Chen;Nengjun Yu;Minggang Zhu;Wei Li;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Microstructure and Magnetic Properties of CoFe Nanowires and Helical Nanosprings
Abstract:
Magnetic nanosprings have applications in various fields, e.g., in sensors, actuators, and biomedical applications. However, it is difficult to synthesize them due to their complicated structure. Here, we report the synthesis of CoFe nanosprings by electrodeposition using vanadium oxide ions and ascorbic acid. The nanosprings have a helical structure and exist in the form of the Co53Fe47 alloy. Hysteresis curves of CoFe nanowire and nanospring arrays show soft ferromagnetic characteristics. The CoFe nanowires have shape anisotropy with an easy axis parallel to the array direction, whereas the CoFe nanosprings exhibit an isotropic behavior.
Autors: Da Yeon Nam;Su Hyo Kim;Yoo Sang Jeon;Young Keun Kim;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Microstructure and Magnetic Properties of Recycled Nd–Fe–B Magnets with Blending of Ce-Rich Alloy
Abstract:
Waste Nd–Fe–B sintered magnets (grade 33H) were recycled to manufacture anisotropic sintered magnets by adding Ce-rich alloys. The influences of additive amounts of Ce-rich alloys on the microstructure and magnetic properties of the recycled sintered magnets were investigated. It showed that the recycled sintered Nd–Fe–B magnet without Ce-rich alloy addition has rather lower density; the density of the magnet is slightly raised with increased sintering temperature, but the recycled magnet is prone to oxidation, even cracking. For recycled sintered magnets with Ce-rich alloy addition, the densities of the magnets are upgraded with increasing amounts of Ce-rich alloy, and the magnetic properties are obviously improved. This suggests that Ce-rich alloy plays the important role of sintering-aid in the densification of the recycled magnet. However, the coercivity () of the recycled magnets is decreased, when the additive amounts of Ce-rich alloy are over 8 wt.%. This is probably because excessive Ce-rich alloy addition can cause RE-rich phase aggregation at the triple grain boundary junctions, and deteriorate the microstructure of the recycled magnets. The recycled magnet with 5 wt.% Ce-rich alloy, sintered at 1080 °C, exhibits the following optimal magnetic properties: of 11.67 kGs; of 18.94 kOe; and maximum energy product of 33.1 MGOe. The magnetic properties of the recycled magnets are comparative to those of the waste magnets. Recycled magnets have a hi- her coercivity and perfect squareness of demagnetization curve ().
Autors: Haibo Feng;Yueming Zhang;Anhua Li;Yang Zhao;Wei Li;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Microwave Passive Ground-Based Retrievals of Cloud and Rain Liquid Water Path in Drizzling Clouds: Challenges and Possibilities
Abstract:
Satellite and ground-based microwave radiometers are routinely used for the retrieval of liquid water path (LWP) under all atmospheric conditions. The retrieval of water vapor and LWP from ground-based radiometers during rain has proved to be a difficult challenge for two principal reasons: the inadequacy of the nonscattering approximation in precipitating clouds and the deposition of rain drops on the instrument’s radome. In this paper, we combine model computations and real ground-based, zenith-viewing passive microwave radiometer brightness temperature measurements to investigate how total, cloud, and rain LWP retrievals are affected by assumptions on the cloud drop size distribution (DSD) and under which conditions a nonscattering approximation can be considered reasonably accurate. Results show that until the drop effective diameter is larger than ~200 , a nonscattering approximation yields results that are still accurate at frequencies less than 90 GHz. For larger drop sizes, it is shown that higher microwave frequencies contain useful information that can be used to separate cloud and rain LWP provided that the vertical distribution of hydrometeors, as well as the DSD, is reasonably known. The choice of the DSD parameters becomes important to ensure retrievals that are consistent with the measurements. A physical retrieval is tested on a synthetic data set and is then used to retrieve total, cloud, and rain LWP from radiometric measurements during two drizzling cases at the atmospheric radiation measurement Eastern North Atlantic site.
Autors: Maria P. Cadeddu;Roger Marchand;Emiliano Orlandi;David D. Turner;Mario Mech;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6468 - 6481
Publisher: IEEE
 
» Microwave Signatures of Snow Cover Using Numerical Maxwell Equations Based on Discrete Dipole Approximation in Bicontinuous Media and Half-Space Dyadic Green's Function
Abstract:
A three-dimensional snowpack scattering and emission model is developed by numerically solving Maxwell's equations (NMM3D) over the entire snowpack on an underlying half-space. The solutions are crucial to microwave remote sensing that requires the preservation of coherent phase information. The heterogeneous snowpack is represented as a bicontinuous medium. Effects of the underlying half-space are included through a half-space Green's function in a volume integral equation formulation. The volume integral equation is then solved using the discrete dipole approximation. The fast Fourier transform is effectuated for all three dimensions with half-space Green's function rather than the conventional free space Green's function. To overcome the snow volume truncation in the finite numerical calculations, periodic boundary conditions are applied in the lateral extent. Thus, in NMM3D, the physical microwave scattering and emission problem is solved without using any radiative transfer equations. In this formulation, the scattering matrix of the snowpack accounts for both the magnitude and phase. The NMM3D simulations are demonstrated at Ku-band frequency for a snow cover up to 25-cm thick. The results are applicable to remote sensing of snow over sea ice, and thin layers of terrestrial snow. Quantitative values of backscattering and bistatic scattering coefficients are derived for active microwave remote sensing, and brightness temperatures for passive microwave remote sensing. The full wave simulation results are compared with those of the partially coherent approach of the dense media radiative transfer (DMRT). The NMM3D results capture effects of backscattering enhancement and coherent layering that are missed in DMRT. The full wave solution to Maxwell equations is important to advance radar polarimetry, interferometry, and tomography that require the preservation of the full - hase information and all interface interactions for applications to radar remote sensing of snow cover on land and on sea ice.
Autors: Shurun Tan;Jiyue Zhu;Leung Tsang;Son V. Nghiem;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 4686 - 4702
Publisher: IEEE
 
» Middle Managers’ Engagement in Autonomous Strategic Actions: Does It Really Matter How Top Managers Use Budgets?
Abstract:
Fostering middle managers’ entrepreneurial behavior is a key concern for established firms. Budgets are one of the most widely used management tools in organizations, and several conceptual articles claim that the way in which they are used, most notably in an interactive way, affects middle managers’ autonomous strategic actions (ASA). This type of entrepreneurial behavior in established firms focuses on opportunities outside the firms’ currently served product-market domains. Using structural equation modeling and a formative measurement instrument for interactive use of budgets, we test these claims advanced in conceptual literature within a broad sample of large firms. We find that the way in which budgets are used does not significantly impact middle managers’ engagement in ASA. In contrast, firms’ boundary systems and middle managers’ autonomy seem important antecedents to ASA.
Autors: Stefan Linder;Simon S. Torp;
Appeared in: IEEE Transactions on Engineering Management
Publication date: Nov 2017, volume: 64, issue:4, pages: 450 - 463
Publisher: IEEE
 
» Millimeter Wave Plasma Formation Within a 2D Photonic Crystal
Abstract:
Experiments demonstrate gas breakdown within a single point defect in a 2D photonic crystal at millimeter wave frequencies (43.44 GHz) using only 1.5 W of continuous wave input power. We show that after formation of the plasma within the defect, the transmission of energy through the crystal is decreased by two to four orders of magnitude for gas pressures from 30 to 750 torr. Time domain measurements of the transmitted energy through the device show plasma formation times ranging from 800 ns at 45 torr to 180 ns at 400 torr of argon gas. Electron density of the plasma is 1018 m−3 at low pressures and up to 1020 m−3 at 750 torr.
Autors: Stephen G. Parsons;Jeffrey Hopwood;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1602 - 1605
Publisher: IEEE
 
» Millimeter Wave Resistance of Metal-Dielectric $text{Co}_{rm x}(text{SiO}_{2})_{rm{1-x}}$ and $text{Co}_{rm x}(text{Al}_{2}text{O}_{3})_{rm{1-x}}$ Films
Abstract:
Transmission and reflection of millimeter waveband electromagnetic waves have been studied for thin-film metal-dielectric and nanocomposite materials, where cobalt nanoparticles are placed inside or films of 100 nm thickness. The microwave properties of the nanocomposite samples with different cobalt content have been measured in the frequency ranges from 26 to 38 GHz and from 53 to 77 GHz. Frequency dependencies of transmission and reflection coefficients have been measured. Power loss in the samples has been determined. An algorithm for recovering the conductivity from the frequency dependencies of the transmission and reflection coefficients has been worked out. It has been found that the microwave conductivity increases with increasing cobalt content and differs drastically from the dc conductivity. The obtained results have been compared to the actual measurements of magnetic properties.
Autors: Anatoly B. Rinkevich;Dmitry V. Perov;Vladimir O. Vaskovsky;Alexandr N. Gorkovenko;Evgeny A. Kuznetsov;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 1067 - 1072
Publisher: IEEE
 
» Miniature Tri-Axis Magnetometer With In-Plane GMR Sensors
Abstract:
A miniature tri-axis magnetometer with in-plane giant magnetoresistance (GMR) sensors and a fluxguide was designed, implemented, and characterized in this paper. Three GMR sensor dies were aligned on a printed circuit board with their sensing directions in the same plane. By using the flux bending effect of a fluxguide, the magnetic field components in the mounting plane of GMR sensors were generated, and hence, the effective sensing directions are not in the same plane. The tilt of effective sensing direction from the mounting plane allows the device to detect the out-of-plane field component. When the device was used as an electronic compass, the digitally demodulated sensor outputs were converted into the orthogonal geomagnetic field components by using a real-time conversion process with the voltage-to-field transfer matrix. The result shows that the device is suitable for compass application. Further works to implement the similar design on a CMOS chip with integrated GMR elements and a planar modulation coil will realize a compact and easy-to-fabricate tri-axis magnetic field sensor.
Autors: Xuan-Thang Trinh;Jen-Tzong Jeng;Chih-Cheng Lu;Min-Jia Lan;Bo-Chen Chen;Jen-Hwa Hsu;Van-Su Luong;Hua-Yi Hsu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Minimizing and Managing Cloud Failures
Abstract:
Guaranteeing high levels of availability is a huge challenge for cloud providers. The authors look at the causes of cloud failures and recommend ways to prevent them and to minimize their effects when they occur.
Autors: Patricia Takako Endo;Guto Leoni Santos;Daniel Rosendo;Demis Moacir Gomes;André Moreira;Judith Kelner;Djamel Sadok;Glauco Estácio Gonçalves;Mozhgan Mahloo;
Appeared in: Computer
Publication date: Nov 2017, volume: 50, issue:11, pages: 86 - 90
Publisher: IEEE
 
» Minimizing Probing CostWith mRMR Feature Selection in Network Monitoring
Abstract:
Periodically monitoring the state of internal links is important for network diagnosis. In this letter, we consider the problem of minimizing probing cost in tomography-based network monitoring. We propose a new algorithm to select the informative probing paths by means of maximum relevance minimum redundancy (mRMR) method. mRMR has been widely used in the field of feature selection. Through the proposed scheme, the paths are regarded as features, and the ones that strongly relevant with link state are picked. We conduct simulation experiments of congested detection, demonstrating that the most useful paths for locating the congested links are chosen through the proposed scheme.
Autors: XiaoBo Fan;Xingming Li;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2400 - 2403
Publisher: IEEE
 
» Minimum-Based Sliding Window Detectors in Correlated Pareto Distributed Clutter
Abstract:
Recent investigations have resulted in the derivation of a multivariate Pareto model, which is consistent with the compound Gaussian model framework, allowing one to describe statistically a correlated Pareto distributed sequence. This has permitted the development of noncoherent sliding window detection processes, for operation in an X-band maritime surveillance radar context, which account for correlated clutter returns. Based upon this multivariate Pareto model, the structure of the sample minimum is investigated, which can then be used to produce decision rules robust to interference. Two such detectors will be examined, and their performance in real high-resolution X-band maritime radar clutter will be investigated. It will be shown that a number of avenues of future work are available.
Autors: Graham V. Weinberg;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1958 - 1962
Publisher: IEEE
 
» Minimum-Reactive-Power Scheme of Dual-Active-Bridge DC–DC Converter With Three-Level Modulated Phase-Shift Control
Abstract:
This paper presents a novel reactive-power minimization method under the three-level modulated phase-shift control to improve the efficiency for a wide operation condition. First, in order to unify all operation modes, a mathematic model of the dual-active-bridge converter with the three-level modulated phase-shift control by a harmonic analysis method is obtained. Then, the detailed analysis of the odd-order harmonic components of the active and reactive powers varied with the multiple control dimensions is presented. The soft-switching boundaries with respect to the voltage ratio and unified active power are specified. On this basis, a novel optimal three-level phase-shift (OPS) control strategy for minimizing reactive power is proposed. Experimental results of reactive power and operation efficiency among the proposed OPS method, and other methods are compared to verify the effectiveness of the OPS algorithm.
Autors: Haochen Shi;Huiqing Wen;Jie Chen;Yihua Hu;Lin Jiang;Guipeng Chen;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5573 - 5586
Publisher: IEEE
 
» Mitigating Deep Dielectric Charging Effects in Space
Abstract:
Deep dielectric charging/discharging is a serious space environmental effect. Charging electric fields are the fundamental cause of dielectric discharging. In order to quantitatively mitigate deep dielectric charging effects, the GEANT4 toolkit and radiation-induced conductivity model were used to calculate the maximum possible internal charging potential and electric field with different shielding layer thicknesses, dielectric thicknesses, and ground types. The study selected electron spectra from geostationary earth orbit (GEO) and jupiter orbits as the input environment. With these calculations, a criterion for shielding, dielectric thickness, and ground types is provided such that spacecraft engineers may choose the appropriate method to decrease the deep dielectric charging effects. The charging time constants of flame retardant 4 and polytetrafluoroethylene are ~20 and 500 h, respectively, with a little dependence on input electron spectra, ground type, shield thickness, or dielectric thickness. The dielectric characteristics, ground types, and thicknesses, which can significantly change the value of the electric field, are critical for preventing deep dielectric charging. The maximum saturation charging potential and electric field at jupiter orbit are much larger than those at GEO.
Autors: Yu Xiangqian;Chen Hongfei;Zong Qiugang;Wang Jianzhao;Shi Weihong;Zou Hong;Zou Jiqing;Zhong Weiying;Chen Zhe;Shao Sipei;Jia Xianghong;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: Nov 2017, volume: 64, issue:11, pages: 2822 - 2828
Publisher: IEEE
 
» Mitigating Silent Data Corruptions in Integer Matrix Products: Toward Reliable Multimedia Computing on Unreliable Hardware
Abstract:
The generic matrix multiply (GEMM) routine comprises the compute and memory-intensive parts of many information retrieval, machine learning, and object recognition systems that process integer inputs. Therefore, it is of paramount importance to ensure that integer GEMM computations remain robust to silent data corruptions (SDCs), which stem from accidental voltage or frequency overscaling, or other hardware nonidealities. In this paper, we introduce a new method for SDC mitigation based on the concept of numerical packing. The key difference between our approach and all existing methods is the production of redundant results within the numerical representation of the outputs, rather than as a separate set of checksums. Importantly, unlike well-known algorithm-based fault tolerance approaches for GEMM, the proposed approach can reliably detect the locations of the vast majority of all possible SDCs in the results of GEMM computations. An experimental investigation of voltage-scaled integer GEMM computations for visual descriptor matching within state-of-the-art image and video retrieval algorithms running on an Intel i7-4578U 3 GHz processor shows that SDC mitigation based on numerical packing leads to comparable or lower execution and energy-consumption overhead in comparison with all other alternatives.
Autors: Ijeoma Anarado;Mohammad Ashraful Anam;Fabio Verdicchio;Yiannis Andreopoulos;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Nov 2017, volume: 27, issue:11, pages: 2476 - 2489
Publisher: IEEE
 
» Mitigation of Alien Crosstalk for Downstream DSL Impaired by Multiple Interferers
Abstract:
Alien crosstalk is one of the major impairments for copper-based transmissions. This letter outlines a method for mitigating alien crosstalk for digital subscriber line downstream transmissions impaired by multiple interference sources. The method requires a reference channel, and includes a post-processing stage in which induced correlation is applied to prepare the interference at the target channel to be reasonably removed by a prediction-based mitigation step. The results show that the proposed method outperforms published alien crosstalk mitigation methods as the number of interference sources increase in G.fast scenarios.
Autors: Diego Gomes;Eduardo Medeiros;Aldebaro Klautau;Evaldo Pelaes;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2380 - 2383
Publisher: IEEE
 
» Mitigation of TMR Using Energy Ratio and Bit-Flipping Techniques in Multitrack Multihead BPMR Systems
Abstract:
Track misregistration (TMR) in ultra-high density bit-patterned media recording (BPMR) is one of the crucial problems, because it can severely degrade the overall system performance. In practical, TMR can be detected and adjusted by a servo control loop system. However, this paper proposes to utilize multiple readback signals obtained from the optimized positioning of the two side read head closer to the main read head to improve the TMR prediction process in a multitrack multi-head BPMR system with position jitter noise. In addition, we also propose the soft-information exchange and the bit-flipping techniques for the multitrack data detection, so as to improve the bit-error rate (BER) performance of all three data tracks simultaneously. Simulation results indicate that the proposed system is superior to the conventional system, especially, when the amount of TMR and position jitter is high. Furthermore, we also found that the upper and lower read heads, which are moved closer to the center track by 25% of a track pitch, will provide the best BER performance with and without position jitter noise.
Autors: Chanon Warisarn;Wiparat Busyatras;Lin M. M. Myint;Santi Koonkarnkhai;Piya Kovintavewat;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Mixture-Based Modeling of Spatially Correlated Interference in a Poisson Field of Interferers
Abstract:
As the interference in PPP-based wireless networks exhibit spatial correlation, any joint analysis involving multiple spatial points either end up with numerical integrations over or become analytically too intractable. To tackle these issues, we present an alternate approach which not only offers a simpler analytical structure, but also closely mimics the PPP characteristics. This approach at its core models the correlated interferences using a correlation framework constructed using random variable mixtures. In addition, a correlation framework based on the more standard method of linear combination of random variables is also presented for comparison purpose. The performance of these models is studied by deriving the joint complementary cumulative distribution function of signal-to-interference ratios at arbitrary points. The plots are found to tightly approximate the exact PPP-based results, with the tightness depending on the values of (interferer intensity), (path loss exponent), and . The applicability of the mixture-based model is also shown for a multi-antennae MRC receiver where only major derivation steps that simplify the outage probability analysis are shown.
Autors: Arindam Ghosh;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2496 - 2499
Publisher: IEEE
 
» Mn–Zn Ferrite Nanoparticles With Silica and Titania Coatings: Synthesis, Transverse Relaxivity, and Cytotoxicity
Abstract:
Mn–Zn ferrite nanoparticles of composition Mn0.61Zn0.42Fe1.97O4 and mean size of crystallites nm are synthesized under hydrothermal conditions as a single-phase product. Subsequently, two coated samples are prepared by encapsulation of the ferrite particles into silica and titania. Transmission electron microscopy confirms the core–shell structure of the products and shows that the cores are actually formed by small clusters of ferrite crystallites. Powder X-ray diffraction, combined with experimental hydrothermal treatment of the titania-coated product, demonstrates that the titania coating is amorphous but can easily be transformed into anatase. The colloidal stability of nanoparticles in water is evidenced by dynamic light scattering, and the respective hydrodynamic sizes are and 157 nm for the silica-coated and titania-coated particles. The colloidal behavior is confirmed based on the measurements of zeta potential, whose negative values lead to strong Coulombic repulsion among coated particles. Magnetic measurements on bare and coated particles show high magnetization of Mn0.61Zn0.42Fe1.97O4 cores and superparamagnetic state at room temperature. The relaxometric study on aqueous suspensions in magnetic fields of 0.5 and 11.75 T reveals high transverse relaxivity of the samples and two distinct forms of its temperature dependence, which are analyzed with respect to the role of temperature-dependent parameters, that is, the diffusion of water and the magnetization of ferrite cores. Finally, careful evaluation of cytotoxicity of coated particles is carried out by using two different methods, namely, the determination of viability and proliferation o- Jurkat cells and the real-time monitoring of attachment and proliferation of A549 cells. In the studied range of concentrations, the viability and proliferation of suspension cells are not affected, and only negligible effects are detected in the cell index of adherent cells.
Autors: Ondřej Kaman;Jarmila Kuličková;Miroslav Maryško;Pavel Veverka;Vít Herynek;Radim Havelek;Karel Královec;Denisa Kubániová;Jaroslav Kohout;Petr Dvořák;Zdeněk Jirák;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 8
Publisher: IEEE
 
» Mobile Unmanned Aerial Vehicles (UAVs) for Energy-Efficient Internet of Things Communications
Abstract:
In this paper, the efficient deployment and mobility of multiple unmanned aerial vehicles (UAVs), used as aerial base stations to collect data from ground Internet of Things (IoT) devices, are investigated. In particular, to enable reliable uplink communications for the IoT devices with a minimum total transmit power, a novel framework is proposed for jointly optimizing the 3D placement and the mobility of the UAVs, device-UAV association, and uplink power control. First, given the locations of active IoT devices at each time instant, the optimal UAVs’ locations and associations are determined. Next, to dynamically serve the IoT devices in a time-varying network, the optimal mobility patterns of the UAVs are analyzed. To this end, based on the activation process of the IoT devices, the time instances at which the UAVs must update their locations are derived. Moreover, the optimal 3D trajectory of each UAV is obtained in a way that the total energy used for the mobility of the UAVs is minimized while serving the IoT devices. Simulation results show that, using the proposed approach, the total-transmit power of the IoT devices is reduced by 45% compared with a case, in which stationary aerial base stations are deployed. In addition, the proposed approach can yield a maximum of 28% enhanced system reliability compared with the stationary case. The results also reveal an inherent tradeoff between the number of update times, the mobility of the UAVs, and the transmit power of the IoT devices. In essence, a higher number of updates can lead to lower transmit powers for the IoT devices at the cost of an increased mobility for the UAVs.
Autors: Mohammad Mozaffari;Walid Saad;Mehdi Bennis;Mérouane Debbah;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7574 - 7589
Publisher: IEEE
 
» Mobility-Aware User Association in Uplink Cellular Networks
Abstract:
This letter studies the mobility aware user-to-base station (BS) association policies, within a stochastic geometry framework, in two-tier uplink cellular networks with fractional channel inversion power control. Particularly, we model the BSs’ locations using the widely accepted Poisson point process and obtain the coverage probability and handover cost expressions for the coupled and decoupled uplink and downlink associations. To this end, we compute the average throughput for the mobile users and study the merits and demerits of each association strategy.
Autors: Rabe Arshad;Hesham Elsawy;Sameh Sorour;Mohamed-Slim Alouini;Tareq Y. Al-Naffouri;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2452 - 2455
Publisher: IEEE
 
» MOCVD Growth of High Quality InGaAs HEMT Layers on Large Scale Si Wafers for Heterogeneous Integration With Si CMOS
Abstract:
We report on the growth of In0.30Ga0.70As channel high electron mobility transistor (HEMT) epi-layers on a 200-mm Si substrate by metal-organic-chemical-vapor-deposition. The HEMT layers were grown on the Si substrate by using a ~3- thick epitaxial buffer composing of a Ge layer, a GaAs layer, and a compositionally graded and strain relaxed InAlAs layer. The optimized epitaxy has a threading dislocation density of less than cm−2 and a root mean square surface roughness of ~6.7 nm. The device active layers include a -doped InAlAs bottom barrier, a ~15-nm thick InGaAs channel, a ~8-nm InGaP top barrier layer and a heavily doped InGaAs contact layer. MOSHEMTs with channel length down to 130 nm were fabricated. The devices achieve a peak transconductance of at of 0.5 V. The peak effective mobility () in a device with a channel length of 20 device channel was ~3700 cm2/.
Autors: Xuan Sang Nguyen;Sachin Yadav;Kwang Hong Lee;David Kohen;Annie Kumar;Riko I. Made;Kenneth Eng Kian Lee;Soo Jin Chua;Xiao Gong;Eugene A. Fitzgerald;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 456 - 461
Publisher: IEEE
 
» Mode Selection and Resource Allocation in Device-to-Device Communications: A Matching Game Approach
Abstract:
Device to device (D2D) communication is considered as an effective technology for enhancing the spectral efficiency and network throughput of existing cellular networks. However, enabling it in an underlay fashion poses a significant challenge pertaining to interference management. In this paper, mode selection and resource allocation for an underlay D2D network is studied while simultaneously providing interference management. The problem is formulated as a combinatorial optimization problem whose objective is to maximize the utility of all D2D pairs. To solve this problem, a learning framework is proposed based on a problem-specific Markov chain. From the local balance equation of the designed Markov chain, the transition probabilities are derived for distributed implementation. Then, a novel two phase algorithm is developed to perform mode selection and resource allocation in the respective phases. This algorithm is then shown to converge to a near optimal solution. Moreover, to reduce the computation in the learning framework, two resource allocation algorithms based on matching theory are proposed to output a specific and deterministic solution. The first algorithm employs the one-to-one matching game approach whereas in the second algorithm, the one-to many matching game with externalities and dynamic quota is employed. Simulation results show that the proposed framework converges to a near optimal solution under all scenarios with probability one. Moreover, our results show that the proposed matching game with externalities achieves a performance gain of up to 35 percent in terms of the average utility compared to a classical matching scheme with no externalities.
Autors: S. M. Ahsan Kazmi;Nguyen H. Tran;Walid Saad;Zhu Han;Tai Manh Ho;Thant Zin Oo;Choong Seon Hong;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Nov 2017, volume: 16, issue:11, pages: 3126 - 3141
Publisher: IEEE
 
» Mode Transition Control Strategy for Multiple Inverter-Based Distributed Generators Operating in Grid-Connected and Standalone Mode
Abstract:
This paper proposes a novel automatic mode transition control strategy for multiple inverters to operate in grid-connected and standalone modes. When grid is available, these inverters feed power the grid by operating in current control mode. Upon grid failure, all inverters automatically shift to droop control mode for achieving proportional power sharing and shift back to current control mode when the grid becomes available. The synthesis of dual structure control algorithms of various inverters is achieved using novel state machines. These state machines are designed to facilitate smooth mode transition of the inverters. In this way, the control signals for mode transition are generated by state machines specific to each inverter. Unlike existing control methods, the proposed method neither requires communication-based supervisory control of inverters nor it requires dedicated storage facility for achieving smooth mode transition. The proposed control strategy is tested on a simulation model as well as an experimental prototype multi-inverter system.
Autors: Onkar Vitthal Kulkarni;Suryanarayana Doolla;B. G. Fernandes;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5927 - 5939
Publisher: IEEE
 
» Model Transformation Modularization as a Many-Objective Optimization Problem
Abstract:
Model transformation programs are iteratively refined, restructured, and evolved due to many reasons such as fixing bugs and adapting existing transformation rules to new metamodels version. Thus, modular design is a desirable property for model transformations as it can significantly improve their evolution, comprehensibility, maintainability, reusability, and thus, their overall quality. Although language support for modularization of model transformations is emerging, model transformations are created as monolithic artifacts containing a huge number of rules. To the best of our knowledge, the problem of automatically modularizing model transformation programs was not addressed before in the current literature. These programs written in transformation languages, such as ATL, are implemented as one main module including a huge number of rules. To tackle this problem and improve the quality and maintainability of model transformation programs, we propose an automated search-based approach to modularize model transformations based on higher-order transformations. Their application and execution is guided by our search framework which combines an in-place transformation engine and a search-based algorithm framework. We demonstrate the feasibility of our approach by using ATL as concrete transformation language and NSGA-III as search algorithm to find a trade-off between different well-known conflicting design metrics for the fitness functions to evaluate the generated modularized solutions. To validate our approach, we apply it to a comprehensive dataset of model transformations. As the study shows, ATL transformations can be modularized automatically, efficiently, and effectively by our approach. We found that, on average, the majority of recommended modules, for all the ATL programs, by NSGA-III are considered correct with more than 84 percent of precision and 86 percent of recall when compared to manual solutions provided by active developers. The statistical anal- sis of our experiments over several runs shows that NSGA-III performed significantly better than multi-objective algorithms and random search. We were not able to compare with existing model transformations modularization approaches since our study is the first to address this problem. The software developers considered in our experiments confirm the relevance of the recommended modularization solutions for several maintenance activities based on different scenarios and interviews.
Autors: Martin Fleck;Javier Troya;Marouane Kessentini;Manuel Wimmer;Bader Alkhazi;
Appeared in: IEEE Transactions on Software Engineering
Publication date: Nov 2017, volume: 43, issue:11, pages: 1009 - 1032
Publisher: IEEE
 
» Model-Based Estimation of the Communication Cost of Hybrid Data-Parallel Applications on Heterogeneous Clusters
Abstract:
Heterogeneous systems composed of CPUs and accelerators sharing communication channels of different performance are getting mainstream in HPC but, at the same time, they show a complexity that makes it difficult to optimize the deployment of a data parallel application. Recent analytical tools such as Functional Performance Models, combined with advanced partitioning algorithms, manage to achieve a balanced configuration by distributing the workload unevenly, according to the performance of the different processing units. Unfortunately, such uneven distribution of the computation load leads to communication unbalances that, very often, render worthless the previous workload balancing efforts. Finding the optimal communication scheme without expensive testing on the executing platform requires an analytical approach to the estimation of the communication cost of different configurations of the application. With this goal in mind, we propose and discuss an extension of the -Lop communication performance model to cover heterogeneous architectures. In order to provide a quantitative assessment of this extended model, we conduct experiments with two representative computational kernels, the SUMMA algorithm and the 2D wave equation solver. The -Lop predictions are compared against the HLogGP model and the observed costs for a variety of configurations, hardware resources and problem sizes.
Autors: Juan-Antonio Rico-Gallego;Alexey L. Lastovetsky;Juan-Carlos Díaz-Martín;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Nov 2017, volume: 28, issue:11, pages: 3215 - 3228
Publisher: IEEE
 
» Modeling and Managing Context-Aware Systems’ Variability
Abstract:
This theme issue provides an updated perspective on techniques to manage software system variability at runtime, to make software systems smarter and less dependent on human intervention.
Autors: Kim Mens;Rafael Capilla;Herman Hartmann;Thomas Kropf;
Appeared in: IEEE Software
Publication date: Nov 2017, volume: 34, issue:6, pages: 58 - 63
Publisher: IEEE
 
» Modeling and Optimal Operation of Distributed Battery Storage in Low Voltage Grids
Abstract:
Due to high power in-feed from photovoltaics, it can be expected that more battery systems will be installed in the distribution grid in near future to mitigate voltage violations and thermal line and transformer overloading. In this paper, we present a two-stage centralized model predictive control scheme for distributed battery storage that consists of a scheduling entity and a real-time control entity. To guarantee secure grid operation, we solve a robust multi-period optimal power flow (OPF) for the scheduling stage that minimizes battery degradation and maximizes photovoltaic utilization subject to grid constraints. The real-time controller solves a real-time OPF taking into account storage allocation profiles from the scheduler, a detailed battery model, and real-time measurements. To reduce the computational complexity of the controllers, we present a linearized OPF that approximates the nonlinear AC-OPF into a linear programming problem. Through a case study, we show, for two different battery technologies, that we can substantially reduce battery degradation when we incorporate a battery degradation model. A further finding is that we can reduce battery losses by 30% by using the detailed battery model in the real-time control stage.
Autors: Philipp Fortenbacher;Johanna L. Mathieu;Göran Andersson;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4340 - 4350
Publisher: IEEE
 
» Modeling and Optimization of a Tubular Generator for Vibration Energy Harvesting Application
Abstract:
The modeling and optimization of a direct-drive contactless tubular linear generator are investigated to ensure a highly reliable device with long lifetime for vibration energy harvesting application. A slotless structure is considered to minimize force ripples and simplify the later control. A semi-analytical model based on harmonic Fourier modeling is considered for the calculation of the magnetic field generated by the permanent magnets. Electrical and thermal iterative models are coupled with the magnetic Fourier model into a general optimization tool that is fast and accurate, which is validated by means of a finite element model.
Autors: Léo A. J. Friedrich;Johannes J. H. Paulides;Elena A. Lomonova;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Modeling and Simulation of Deciduous Forest Canopy and Its Anisotropic Reflectance Properties Using the Digital Image and Remote Sensing Image Generation (DIRSIG) Tool
Abstract:
Extraction of biophysical information from forest canopies using temporal analysis of multispectral and hyperspectral data can be significantly improved by understanding its anisotropic reflectance properties. However, limitations on the accessibility and data collection techniques in the field reduce the availability of high-resolution bidirectional reflectance measurements (BRDF) to a few datasets. These limitations can be mitigated in a virtual environment and this paper presents an approach to model the spectral BRDF of a forest canopy using the Digital Image and Remote Sensing Image Generation (DIRSIG) tool. The three-dimensional geometries of the trees were modeled using forest inventory data and OnyxTree, while the spectral properties of the geometric elements were assigned based on the field collected spectra and PROSPECT inversion model. The DIRSIG tool was used as a virtual goniometer to measure the BRDF observations for varying sun-view geometries and a full hemispherical BRDF model was constructed by fitting the measurements to a semiempirical BRDF model. This paper discusses the methods involved in modeling the forest canopy scene, sensitivity of the radiative transfer, BRDF sampling and modeling strategies, model accuracy and its effect on real-world simulations. The model fit results indicate a root mean square error of less than 5% relative to the forests reflectance in the VIS-NIR-SWIR region. The simulated BRDF matched to within 2% of the Landsat-8 surface reflectance product in the red and NIR bands. The results can be used directly to evaluate BRDF modeling algorithms and the proposed method can be easily extended for other biomes.
Autors: Rajagopalan Rengarajan;John R. Schott;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 4805 - 4817
Publisher: IEEE
 
» Modeling Eddy Current Brake Emissions for Electromagnetic Compatibility With Signaling Devices in High-Speed Railways
Abstract:
This paper presents a model that anticipates the emissions from eddy current brakes (ECBs) installed in high-speed trains. The emissions are computed in the 10 KHz–1.3 MHz range, where trackside signaling devices operate and issues related to electromagnetic compatibility have arisen, hindering ECB's promise of full deployment. The electromagnetic model provides a transfer function in the frequency domain between the nondesired harmonic currents produced by the train power supply and the subsequent radiated emissions by the ECBs at the trackside. The model includes the influence of the on-board ECB system's electric circuitry on the three-dimensional field computation of the electromagnets by a cosimulation approach (circuit and electromagnetic cross talk). After the data are postprocessed, the simulated results are compared with the results of an extensive measurement campaign on board a high-speed ICE 3 train equipped with ECBs. The high correlation makes it possible to anticipate ECB emissions in order to save costly on-track test runs, to suggest ECB design strategies and to provide safe limits when the worst cases occur.
Autors: Daniel Valderas;Iker Mesa;Iñigo Adín;Henry Lehmann;Gavin Lancaster;Oliver Stark;Wilhelm Baldauf;Jon del Portillo;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9743 - 9752
Publisher: IEEE
 
» Modeling for Spin-FET and Design of Spin-FET-Based Logic Gates
Abstract:
Spintronics-based devices and circuits attract massive research interest from both academia and industry. A number of the devices and logic circuits have been proposed such as spin-based magnetic tunnel junction and all spin logic gate. A fundamental spin-based device, spin field-effect transistor (spin-FET) is one of the most interesting spin-based devices to address the power issue of semiconductor transistors which is still a research focus. In this paper, we first present an electrical model for the spin-FET based on both theoretical and experimental results. The theories of spin injection and detection are considered by a current driver of the spin-FET. Gate voltage modulation following Datta–Das theory is combined with the experimental results from several works of literature. Afterward, through the dc analysis of two spin-FETs with different channel materials, we demonstrate that the channel using InAs is a better choice to make a feasible spin-FET. The channel length is also optimized by the comparison of simulation results. Finally, a local geometry spin-FET model suitable for logic design is implemented with Verilog-A language and integrated on Cadence platform. Using our model, a low-power inverter is designed based on the concept of complementary spin-FET, and a logic circuit is proposed to implement AND and NOR logic functions. Simulation results validate the behaviors of the logic circuits and availability of our model.
Autors: Gefei Wang;Zhaohao Wang;Jacques-Olivier Klein;Weisheng Zhao;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» Modeling L-Band Synthetic Aperture Radar Data Through Dielectric Changes in Soil Moisture and Vegetation Over Shrublands
Abstract:
L-band airborne synthetic aperture radar observations were made over California shrublands to better understand the effects of soil and vegetation parameters on backscattering coefficient . Temporal changes in of up to 3 dB were highly correlated to surface soil moisture but not to vegetation, even though vegetation water content (VWC) varied seasonally by a factor of two. HH was always greater than VV, suggesting the importance of double-bounce scattering by the woody parts. However, the geometric and dielectric properties of the woody parts did not vary significantly over time. Instead the changes in VWC occurred primarily in thin leaves that may not meaningfully influence absorption and scattering. A physically based model for single scattering by discrete elements of plants successfully simulated the magnitude of the temporal variations in HH, VV, and HH/VV with a difference of less than 0.9 dB for both the mean and standard deviation when compared with the airborne data. In order to simulate the observations, the VWC input of the plant to the model was formulated as a function of plant's dielectric property (water fraction) while the plant geometry remains static in time. In comparison, when the VWC input was characterized by the geometry of a growing plant, the model performed poorly in describing the observed patterns in the changes. The modeling results offer explanation of the observation that soil moisture correlated highly with : the dominant mechanisms for HH and VV are double-bounce scattering by trunk, and soil surface scattering, respectively. The time-series- inversion of the physical model was able to retrieve soil moisture with the difference of (mean), (standard deviation), and 0.89 (correlation), which demonstrates the efficacy of the model-based time-series soil moisture retrieval for shrublands.
Autors: Seung-bum Kim;Motofumi Arii;Thomas Jackson;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 4753 - 4762
Publisher: IEEE
 
» Modeling Microwave Backscattering From Parabolic Rice Leaves
Abstract:
Scattering from rice leaves contributes substantially to total vegetation canopy backscattering and detailed knowledge about it is necessary for developing a microwave scattering model. A parabolic curve is generally adopted to simulate the leaf shape but this is rarely incorporated into the calculation of the scattering. In this paper, two specific models, one based on physical optics (PO) approximation and the other on the discrete dipole approximation (DDA), are presented to involve the parabolic leaf curvature effects. Three typical leaves were chosen from 1433 parabolic leaves obtained during ground measurements. The PO and DDA models were used to calculate the leaf scattering. The generalized Rayleigh–Gans (GRG) approximation was also included in the simulation. The method of moments, a computational electromagnetic method, was utilized to evaluate the accuracy of each model. Validation of the models was conducted at incidence angles ranging from 10° to 60°, incidence azimuthal angles ranging from 0° to 360°, and incidence frequencies of 1.2 GHz (L-band), 5.4 GHz (C-band), and 9.65 GHz (X-band). Among the GRG approximation, the DDA model and the PO model, the latter gave the best accuracy −>65% in the cases tested, while the GRG model was the least accurate. The high accuracy of the PO model was maintained at both the low and high frequency bands. The PO model, therefore, has great potential for use to interpret radar measurements from rice fields and other types of vegetation canopy.
Autors: Long Liu;Yun Shao;Nicolas Pinel;Kun Li;Zhi Yang;Huaze Gong;Youcheng Wang;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6044 - 6053
Publisher: IEEE
 
» Modeling of Differential Power Sensor Based on Seesaw Structure for Microwave Communication Application
Abstract:
Modeling of the differential power sensor based on microelectromechanical systems seesaw membrane is proposed in this paper. When the microwave power is applied, the center part of the membrane is pulled down toward the substrate, while two end parts are turned away from the substrate. The proposed model is based on the theory of simply supported membrane. The displacement of membrane and the capacitance change are both calculated as a function of the incident power. The microwave performance measurement shows that the return loss is less than −12.5 dB and the insertion loss is better than 1.5 dB over 1–10 GHz. The power response measurement demonstrates that the capacitance change magnitudes and both increase with the microwave power, which agrees with the proposed model. For , the measured sensitivity is close to 69.2 aF/mW at 1 GHz, 71.5 aF/mW at 5 GHz, and 66.3 aF/mW at 10 GHz, respectively. For , the sensitivity is close to 35.2 aF/mW at 1 GHz, 33 aF/mW at 5 GHz, and 27.6 aF/mW at 10 GHz, respectively.
Autors: Zhenxiang Yi;Hao Yan;Xiaoping Liao;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4664 - 4670
Publisher: IEEE
 
» Modeling of Hysteresis in Fe–Cu–Nb–Si–B Cores With Transverse Ku
Abstract:
This paper focuses on the modeling of the hysteresis of Fe–Cu–Nb–Si–B nanocrystalline alloys with transverse induced anisotropy based on the behavior of a correlated volume (CV). Only coherent rotation mechanism was considered, given the chosen value of . The formulations account for , the incoherent anisotropy , and the magnetostatic energy. The solving of the equations shows the existence of two kinds of CVs: the first one is responsible for the domain pattern, while the other causes the coercivity. The model has been compared with experimental data, and improved by considering the existence of a minority of CVs featuring strong incoherent anisotropy, causing the coercivity, mingled with classical CVs obeying the random anisotropy model.
Autors: Nicolas Boust;Olivier Geoffroy;Hervé Chazal;James Roudet;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Modeling of Joule Heating Induced Effects in Multiwall Carbon Nanotube Interconnects
Abstract:
Electrothermal performance of multiwall carbon nanotubes (MWCNT)-based interconnects has been studied under the influence of self-heating. The interlayer insulator is a low-k () dielectric. Various geometries have been studied for the normal operation and breakdown conditions. Electrothermal coupled equations have been solved iteratively by solving Fourier heat diffusion equation with a finite-element method. Within the relaxation time approximation, mean free path of the electron has been calculated under different scattering mechanisms. Landauer–Büttiker formalism resistance has been used for calculating electrical resistance. Breakdown voltages for varying MWCNT lengths have been calculated and found to be higher in MWCNT with a shorter length. Breakdown voltage varies from 8.2 to 12 V for inner diameters 10–40 nm of 5- interconnect length and 50-nm outer diameter. Breakdown voltage decreases with the increase in the length of interconnect. For a 5- long interconnect, the breakdown voltage is nearly 8 V whereas for the same diameter long interconnect it is nearly 22 V. Breakdown current density depends on the geometry of the MWCNT and is estimated on the order of A cm−2.
Autors: K. M. Mohsin;Ashok Srivastava;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Nov 2017, volume: 25, issue:11, pages: 3089 - 3098
Publisher: IEEE
 
» Modeling of Magnetohydrodynamics in Nozzle Arc: A Mathematically and Numerically Efficient Approach
Abstract:
This paper deals with the numerical modeling of magnetohydrodynamics (MHD) phenomenon inside a nozzle arc. Previous work for MHD simulation shows that current density is computed from current continuity equation and thereafter the magnetic field is computed by either of the three approaches: A1—Biot-Savart Law; A2—magnetic vector potential equation; and A3—Ampere’s Law. An alternative approach—called here as A4—is proposed here for nozzle arc application. This approach starts with computation of magnetic field from magnetic induction equation, and then current density is computed from Ampere’s Law. The proposed approach is shown to give good agreement with other approaches (reported in the published literature) for low- as well as high-current applications. It is demonstrated that the A4 approach offers two advantages over the most commonly used A2 approach: 1) A4 approach achieves almost same computational accuracy with much less computation time and is thus numerically more efficient and 2) A4 approach is mathematically more efficient as it can be nondimensionalized and used for parametric investigation. A hybrid model is also proposed to demonstrate that the A4 model predicts arc characteristics accurately with little effect of singularity issue.
Autors: Sumedh P. Pawar;Atul Sharma;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 3019 - 3029
Publisher: IEEE
 
» Modeling of Phase-Change Memory: Nucleation, Growth, and Amorphization Dynamics During Set and Reset: Part I—Effective Media Approximation
Abstract:
We have constructed a framework that enables finite-element modeling of nucleation, growth, and amorphization processes in phase-change memory devices using a single rate equation that tracks evolution of local crystal density at each mesh point. The rate equation, current continuity equation, and Fourier heat transfer equation are solved simultaneously to perform electro-thermal simulations that capture the device dynamics during set and reset operations. The functionality of this framework is demonstrated through simulation of various set and reset operations and consecutive set/reset cycles of a mushroom cell using temperature and crystallinity dependent parameters for Ge2Sb2Te5.
Autors: Zachary Woods;Ali Gokirmak;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4466 - 4471
Publisher: IEEE
 
» Modeling the Field of a Coil Using the Magnetic Charge Method
Abstract:
In the last decades, the magnetic charge method has proven to be an excellent tool to analyze and design permanent magnet-based systems. Recent research has shown that the inclusion of the relative permeability of magnetic materials is also possible using the extended charge method. Contrary to popular belief, it is also possible to include currents into the equations for the magnetic field using a fictitious magnetization. In this paper, the fictitious magnetization is calculated and used to determine the field of a rectangular coil. Compared with the current method to calculate the field, on the same computational hardware and software, a large reduction in calculation time (81 versus 11 s) is observed.
Autors: Dave T. E. H. van Casteren;Johannes J. H. Paulides;Elena A. Lomonova;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Modeling the Performance of Nano Machined CMOS Transistors for Uncooled IR Sensing
Abstract:
This paper models the performance and summarizes the design considerations (electrical, mechanical, and thermal) of CMOS-SOI-NEMS (CMOS Silicon on Insulator nanoelectro mechanical systems) transistors fabricated in the 130-nm technology, which perform as uncooled passive infrared (PIR) sensors. The nanmachined CMOS-SOI-NEMS transistors (dubbed TMOS) are isolated thermally by the postprocessing dry etching with high yield and uniformity, achieved at the wafer-level processing as well as the wafer-level packaging, using 8-in wafers. The TMOS transistor is an active sensor with internal gain achieving voltage, responsivity, over V/W. This responsivity is larger by approximately an order of magnitude compared to bolometers, and several orders of magnitude compared to thermopiles or pyros, which are passive devices. The TMOS operates at subthreshold, requiring very low power, of the order of microWatt. Accordingly, this uncooled IR sensor, in the low-cost CMOS-SOI technology, promises to become the standard PIR technology for mobile applications, wearables, and Internet of Things.
Autors: Alex Zviagintsev;Tania Blank;Igor Brouk;Ilan Bloom;Yael Nemirovsky;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4657 - 4663
Publisher: IEEE
 
» Modeling Virtual Humans
Abstract:
Modeling virtual humans has been an important and active research field in computer graphics for many years. Realistically representing a virtual human necessitates that we address several multifaceted challenges, generating realistic locomotion, facial expressions, natural speech, and interaction with clothes and hair. This special issue of IEEE Computer Graphics and Applications focuses on these and other key factors that come into play when modeling virtual humans.
Autors: Jan Bender;Kenny Erleben;Barbara Solenthaler;
Appeared in: IEEE Computer Graphics and Applications
Publication date: Nov 2017, volume: 37, issue:6, pages: 26 - 27
Publisher: IEEE
 
» Modeling, Design Optimization, and Verifications of Permanent Magnet Linear Actuators for Structural Vibration Mitigation Applications
Abstract:
Structural vibrations in modern buildings have been increasing concerns. If not properly controlled, they would give rise to serviceability problems and disturbances to occupants. The permanent magnet (PM) linear actuator-based active vibration mitigation strategy exhibits excellent dynamic performances on elimination of vibrations with complex modes, and has great potential. This paper describes modeling, design optimization, and numerical and experimental verifications of a PM linear actuator for structural vibration mitigation applications. Analytical expressions for prediction of the actuator performance are derived, and the linear actuator is then designed in optimization within a specific set of volumetric and thermal constraints in order to maximize the product of efficiency and power factor. It is shown that the proposed analytical model has provided a computationally efficient tool for design optimization, and the Halbach ratio and actuator width have significant impacts on the performance of the PM linear actuator. The results are validated by finite-element computations, and further verified by experimental measurements on a prototype actuator.
Autors: Qian Wang;Jiabin Wang;Bo Zhao;Yong Li;Hui Zhao;Jing Ma;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Modelling Behaviour in UAV Operations Using Higher Order Double Chain Markov Models
Abstract:
Creating behavioural models of human operators engaged in supervisory control tasks with UAVs is of great value due to the high cost of operator failures. Recent works in the field advocate the use of Hidden Markov Models (HMMs) and derivatives to model the operator behaviour, since they offer interpretable patterns for a domain expert and, at the same time, provide valuable predictions which can be used to detect abnormal behaviour in time. However, the first order Markov assumption in which HMMs rely, and the assumed independence between the operator actions along time, limit their modelling capabilities. In this work, we extend the study of behavioural modelling in UAV operations by using Double Chain Markov Models (DCMMs), which provide a flexible modelling framework in which two higher order Markov Chains (one hidden and one visible) are combined. This work is focused on the development of a process flow to rank and select DCMMs based on a set of evaluation measures that quantify the predictability and interpretability of the models. To evaluate and demonstrate the possibilities of this modelling strategy over the classical HMMs, the proposed process has been applied in a multi-UAV simulation environment.
Autors: Victor Rodriguez-Fernandez;Antonio Gonzalez-Pardo;David Camacho;
Appeared in: IEEE Computational Intelligence Magazine
Publication date: Nov 2017, volume: 12, issue:4, pages: 28 - 37
Publisher: IEEE
 
» Models of Clustered Photolithography Tools for Fab-Level Simulation: From Affine to Flow Line
Abstract:
Fab-level discrete-event simulation is an important practical tool for the analysis and optimization of semiconductor wafer fabricators. In such facilities, a clustered photolithography tool (CPT) is by far the most expensive tool and often the capacity bottleneck. In this paper, we consider linear, affine, flow line, and detailed models of CPTs for use in fab-level simulation. We develop extensions to affine and flow line models and demonstrate exactly how to convert raw CPT data into the various models. Using a detailed CPT model based on industry data as the baseline, numerical experiments are conducted to test the models’ fidelity for cycle time, lot residency time, and throughput. We also compare the computational burden of each model class. Further simulations are conducted to test the models’ robustness to changing fab conditions, e.g., when lot size or train size changes. Flow line models are shown to be more accurate and robust than linear or affine models and require approximately 200 times less computation than detailed models.
Autors: Jung Yeon Park;Kyungsu Park;James R. Morrison;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 547 - 558
Publisher: IEEE
 
» Modified Boost Derived Hybrid Converter: Redemption Using FCM
Abstract:
Boost-derived hybrid converter (BDHC) is a single-stage converter that produces both dc and ac output voltages. The operation of BDHC under continuous conduction mode is satisfactory. However, the nonzero discontinuous conduction mode (NZ-DCM) and standalone ac operation restrict the stable operation of the converter. To mitigate these limitations, modified BDHC (MBDHC) is proposed in this paper. The main idea behind these changes is to redeem NZ-DCM by forced continuous conduction mode (FCM). The adverse effect of NZ-DCM in a BDHC is analyzed in terms of ac output voltage total harmonic distortion, and dc output voltage ripple. This analysis is further extended for MBDHC to highlight the benefits of FCM. Moreover, for hybrid loads, the efficiency of MBDHC is compared with its counterpart BDHC and cascaded boost inverter.
Autors: Avneet K. Chauhan;Venkata R. Vakacharla;M. M. Reza;M. Raghuram;Santosh Kumar Singh;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5893 - 5904
Publisher: IEEE
 
» Modular Assembly of a Single-Phase Inverter Based on Integrated Functional Blocks
Abstract:
This paper presents an original modular plug-in-type assembly approach for a single-phase inverter. The main focus here is, indicatively, on the power range 1–20 kW, but the methodology can be transferred to higher power levels too. At the core of the inverter lies a power-dense double-sided-cooled half-bridge power switch architecture with integrated cooler, which is interconnected to filter elements, gate driver, and control circuitry by means of compact flat connectors. The integration exercise targets, on the one hand, the optimization of the power switch performance and reliability, as well as the reduction of circuit parasitic elements; on the other, the production of a system compatible with maintenance and repairing, featuring minimized impact of single component failure on the system maintenance and repair cost, and, thus, on its availability. Preliminary experimental tests demonstrate the nominal functionality of the inverter.
Autors: Alberto Castellazzi;Adane Kassa Solomon;Nicola Delmonte;Paolo Cova;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5687 - 5697
Publisher: IEEE
 
» Modular Test System Architecture for Device, Circuit, and System Level Reliability Testing and Condition Monitoring
Abstract:
Reliability stress testing of power semiconductors requires significant development effort for a test apparatus to provide the required functionality. This paper presents a modular test system (MTS) architecture that focuses on flexibility, reusability, and adaptability to future test requirements. Different types of tests for different devices in application circuit configuration can be implemented based on the same MTS concept. Vital parameters of the device under test can be acquired in situ during the running stress test. This enables the collection of drift data of these parameters. The control and data acquisition parts of the test system are clearly separated from the actual test circuit. With this physical separation, the same control part can be used for different types of tests. Experimental results of an already implemented test system are provided.
Autors: Roland Sleik;Michael Glavanovics;Sascha Einspieler;Annette Muetze;Klaus Krischan;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5698 - 5708
Publisher: IEEE
 
» Modulating Ring Structural Configuration Influence on the Dual Air-Gap Magnetic Gear Electric Machine
Abstract:
In this paper, a study was conducted using a unit equivalent magnetic circuit (EMC) in correlating the relationship between the magnet thickness, the modulating ring pole-piece thickness, and their circumferential pitch. A numerical optimization method is employed in selecting the optimum ratio of the magnet to pole-piece thickness. The study reveals the need to simultaneously consider these parameters during the design of a magnetic gear electric machine because of their strong mutual dependency. A finite element analysis (FEA) was conducted using the optimum ratios. The results correspond to those of the EMC. Also, the performance of the machine is analyzed and found to have a power factor of 0.78. To further verify the results of FEA, a prototype was built using the same configurations of the FEA model. Measurements taken from the prototype are on par with the simulated results.
Autors: Chinweze U. Ubadigha;Mi-Ching Tsai;Min-Fu Hsieh;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» Modulation of Parkinsonian State With Uncertain Disturbance Based on Sliding Mode Control
Abstract:
Parkinson’s disease (PD) is a degenerative disorder of central nervous system that endangers the olds’ health seriously. The motor symptoms of PD can be attributed to the distorted relay reliability of thalamus to cortical sensorimotor input that results from the increase of inhibitory input from internal segment of the globus pallidum (GPi). Based on this, we construct the GPi-thalamocortical computational model to generate the normal and pathological firing patterns by varying GPi spike train input. A kind of closed-loop deep brain stimulation (DBS) strategy is proposed here. Our control objective is to make the controlled membrane potential of the thalamic neuron return to the normal firing pattern. The control input that directly acts on the thalamus is the DBS waveform, which is adjusted in real time according to the feedback signal. Aimed at a certain system without the change of object parameters or stochastic disturbance, the input–output feedback linearization method is able to eliminate the error between the system output and the desired output. When uncertain elements taken into consideration in the system, the simulation results indicate that sliding mode control scheme provides better effectiveness and higher robustness.
Autors: Yulin Zhu;Jiang Wang;Huiyan Li;Bin Deng;Chen Liu;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Nov 2017, volume: 25, issue:11, pages: 2026 - 2034
Publisher: IEEE
 
» Momentum Space Engineering of GaN HETs for RF Applications Through Full-Band Monte Carlo Simulations
Abstract:
The effect of the structure of the emitter barrier on the performance of GaN hot electron transistors (HETs) is investigated through the description of the hot electrons dynamics in the base region obtained with full-band Monte Carlo simulations. From the momentum distribution of the hot electrons in the base, it is found that the injection of carriers in the satellite valleys is limiting the current gain. A new layout with shorter emitter barrier layer reduces the number of electrons in the satellite valleys and shows an increase of the current gain by a factor of 3. The velocity and energy electron distribution are also calculated for the two devices to show the impact of the satellite valley population on the dynamics of the hot electrons. Several designs of the emitter barrier are proposed based on different AlGaN alloys, yielding cutoff frequencies up to 270 GHz. The design of the collector barrier is found to be related to the power performances highlighting a tradeoff between the maximum output power and the device efficiency. The present analysis provides insight on the operation of these new devices and guidelines to improve the dc and ac small- and large-signal performances of GaN HETs.
Autors: Riccardo Soligo;Flavio Sabatti;Srabanti Chowdhury;Marco Saraniti;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4442 - 4449
Publisher: IEEE
 
» Monitoring Radiated Coexistence Testing Using GMM-Based Classifier
Abstract:
Sharing spectrum resources in unlicensed bands grants vehicular applications inexpensive and ubiquitous access to wireless services. However, wireless technology coexistence concerns are gaining increased attention. In response, coexistence test methods are now being reported in the literature, and novel solutions are considered in the American National Standards Institute C63.27 Standard for Evaluation of Wireless Coexistence. Furthermore, the IEEE 802 standards committee formed a new study group, named wireless automotive coexistence, operating under the umbrella of 802.19 working group to highlight the increasing concerns of wireless coexistence in the automotive domain. The radiated open environment coexistence test (ROECT) method offers high flexibility to test wireless devices for coexistence. Radio signal propagation during testing is over the air, reducing access to the signal path. Consequently, monitoring instantaneous device performance is a challenge yet to be addressed. This paper introduces a novel method for estimating the channel utilization of multiple, concurrent wireless transmitters sharing the 2.4-GHz ISM band in the context of ROECT. Passively received power measurements were collected during testing, and then a Gaussian mixture model was used to build a classifier for labeling observed power samples relative to their source. Case studies utilizing IEEE 802.11n as an interfering system with an under test system based on either IEEE 802.11n or ZigBee are detailed. Findings demonstrate the mutual effect of spectrum sharing on both interfering and under test systems in terms of per-second channel utilization and frame collision. Experimental results show an overall accuracy exceeding 98%.
Autors: Mohamad Omar Al Kalaa;Hazem H. Refai;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10336 - 10345
Publisher: IEEE
 
» Monte Carlo Method for Uncertainty Propagation in Magnetic Resonance-Based Electric Properties Tomography
Abstract:
This paper investigates the uncertainty propagation in magnetic resonance-based electric properties tomography, a quantitative imaging technique that recovers the electric properties distribution inside a human body at the Larmor frequency. This is a needed step in order to make the quantitative results reliable for in vivo applications. To this aim, the contrast source inversion method is investigated as a promising technique and the uncertainty propagation through the corresponding model is studied by means of the Monte Carlo method. Thanks to the increased quality in the recovered electric properties, the results suggest that TEM coils for parallel transmission could be a preferable choice.
Autors: Alessandro Arduino;Mario Chiampi;Francesca Pennecchi;Luca Zilberti;Oriano Bottauscio;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Moore’s Law and Ultra-Low-Power Processors
Abstract:
This column highlights the contents of the issue, including an article based on an ISCA 2017 keynote speech and various departments.
Autors: Lieven Eeckhout;
Appeared in: IEEE Micro
Publication date: Nov 2017, volume: 37, issue:6, pages: 4 - 5
Publisher: IEEE
 
» Morphological Image Analysis of Surface Dielectric Barrier Discharge at Atmospheric Air
Abstract:
Surface dielectric barrier discharge (DBD) has recently received growing interest for enormous application potential in various fields. In this paper, the optical observation of surface DBD is conducted by an intensified charge-coupled device camera from top view in the atmospheric air. Spacial and transient characteristics of discharge phenomenon in atmospheric pressure air have been, respectively, visualized with the exposure time of 100 ms and 5 . The discharge area is obtained by calculating the number of pixels in MATLAB software at different electrical parameters and different high-voltage electrode configurations with microsecond time scale. Experimental measurements show that the diffuse discharge during the negative-half cycle has good uniformity and stability compared with filamentary discharge during the positive-half cycle. The results offer a new estimated method for the discharge area.
Autors: Ying Zhang;Taotao Qin;Jie Li;Yan Wu;Akira Mizuno;Kefeng Shang;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 2988 - 2993
Publisher: IEEE
 
» Motion-Based Temporal Alignment of Independently Moving Cameras
Abstract:
This paper presents a method to establish a nonlinear temporal correspondence between two video sequences captured by cameras independently moving in a dynamic 3D scene. We assume that the 3D spatial poses of the cameras are known for each frame. With predefined trajectory basis, the coefficients of the reconstructed trajectory of a moving scene point reflect the rhythm in motion. A robust rank constraint from the coefficient matrices is exploited to measure the spatiotemporal alignment quality for every feasible pair of video fragments. Point correspondences across sequences are not required or even it is possible that different points are tracked in different sequences, only if they satisfy the assumption that every 3D point tracked in the observed sequence can be described as a linear combination of a subset of the 3D points tracked in the reference sequence. Synchronization is then performed using a graph-based search algorithm to find the globally optimal path that minimizes both spatial and temporal misalignments. Our algorithm can use both complete and incomplete feature trajectories along time, and is robust to mild outliers. We verify the robustness and performance of the proposed approach on synthetic data as well as on challenging real video sequences.
Autors: Xue Wang;Jianbo Shi;Hyun Soo Park;Qing Wang;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Nov 2017, volume: 27, issue:11, pages: 2344 - 2354
Publisher: IEEE
 
» Moving-Object Detection From Consecutive Stereo Pairs Using Slanted Plane Smoothing
Abstract:
Detecting moving objects is of great importance for autonomous unmanned vehicle systems, and a challenging task especially in complex dynamic environments. This paper proposes a novel approach for the detection of moving objects and the estimation of their motion states using consecutive stereo image pairs on mobile platforms. First, we use a variant of the semi-global matching algorithm to compute initial disparity maps. Second, assisted by the initial disparities, boundaries in the image segmentation produced by simple linear iterative clustering are classified into coplanar, hinge, and occlusion. Moving points are obtained during ego-motion estimation by a modified random sample consensus) algorithm without resorting to time-consuming dense optical flow. Finally, the moving objects are extracted by merging superpixels according to the boundary types and their movements. The proposed method is accelerated on the GPU at 20 frames per second. The data which we use for testing and benchmarking is released, thus completing similar data sets. It includes 812 image pairs and 924 moving objects with ground truth for better algorithms evaluation. Experimental results demonstrate that the proposed method achieves competitive results in terms of moving-object detection and their motion state estimation in challenging urban scenarios.
Autors: Long Chen;Lei Fan;Guodong Xie;Kai Huang;Andreas Nüchter;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Nov 2017, volume: 18, issue:11, pages: 3093 - 3102
Publisher: IEEE
 
» MTPA Fitting and Torque Estimation Technique Based on a New Flux-Linkage Model for Interior-Permanent-Magnet Synchronous Machines
Abstract:
The characterization of the interior-permanent-magnet synchronous machine (IPMSM) is limited due to the nonlinearity of the flux-linkage profile by using the conventional motor model. A nonlinear flux-linkage model for the IPMSM with 12 coefficients is proposed in this paper. It can generally be used to estimate the real d-axis flux linkage, q-axis flux linkage, maximum-torque-per-ampere (MTPA) locus, and torque without the information of the machine known, such as the geometry and material of the permanent magnet. The corresponding torque equation and MTPA condition are presented. An optimization problem is formulated to find the appropriate factors for the proposed model based on the measured flux-linkage data at only nine specific operating points. No selection of weight factors is required in the cost function. The desired copper-loss minimization control can be achieved and good torque identification can be implemented in real time. Both simulation and experiment have been conducted to validate the proposed algorithm in motoring and generating modes. Compared with the conventional IPMSM model, the torque estimation accuracy has been significantly improved by considering the saturation and cross-coupling effects in the nonlinear flux-linkage model of the machine.
Autors: Yu Miao;Hao Ge;Matthias Preindl;Jin Ye;Bing Cheng;Ali Emadi;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Nov 2017, volume: 53, issue:6, pages: 5451 - 5460
Publisher: IEEE
 
» Multi-Color Imaging of Magnetic Co/Pt Multilayers
Abstract:
We demonstrate for the first time the realization of a spatial resolved two color, element-specific imaging experiment at the free-electron laser facility FERMI. Coherent imaging using Fourier transform holography was used to achieve direct real space access to the nanometer length scale of magnetic domains of Co/Pt heterostructures via the element-specific magnetic dichroism in the extreme ultraviolet spectral range. As a first step to implement this technique for studies of ultrafast phenomena we present the spatially resolved response of magnetic domains upon femtosecond laser excitation.
Autors: D. Weder;C. Von Korff Schmising;F. Willems;C. M. Günther;M. Schneider;B. Pfau;A. Merhe;E. Jal;B. Vodungbo;J. Lüning;B. Mahieu;F. Capotondi;E. Pedersoli;S. Eisebitt;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Multi-Level Security Embedded With Surveillance System
Abstract:
Graveness of guarding is an essential component of any system or organization in an increasingly hacking environment. Layers of protection are necessary. This paper presents a model to develop a multilevel security system. To reach or access inner most circle, three stages of security system endorsement will be necessary, making it the primary level of security. These include the Hex Keypad, Bluetooth, and RFID. The valuables in the inner vault are further secured with a secondary system completely separate from the primary, consisting of a fingerprint scanner. Any security breach detected will alert the authorities with the help of a GSM Shield, therefore taking the necessary response immediately. Continuous surveillance with online streaming is also demonstrated using Raspberry Pi and a digital camera, further safeguarding the valuables.
Autors: Sanket Goyal;Pranali Desai;Vasanth Swaminathan;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7497 - 7501
Publisher: IEEE
 
» Multi-Sensor Fusion Based on Local Activity Measure
Abstract:
In this paper, a novel yet simple, multi-sensor fusion technique realizes in spatial domain is proposed. The core idea is to obtain the local activity features assuming that all the input images are random fields. This local activity feature matrix, which essentially incorporates the local features of the image, is then used to construct the fused image. In the penultimate step of the proposed technique, the homogeneity of the final fused image is verified by the consistency verification process. The performance of the proposed technique is validated subjectively and objectively by extensive experiments on different multi-sensor images. Furthermore, the comparative analysis with state-of-the-art methods confirmed the escalating improvement of the proposed technique.
Autors: Gaurav Bhatnagar;Zheng Liu;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7487 - 7496
Publisher: IEEE
 
» Multi-Timescale Coordinated Voltage/Var Control of High Renewable-Penetrated Distribution Systems
Abstract:
This paper proposes a multi-timescale coordinated stochastic voltage/var control method for high renewable-penetrated distribution networks. It aims to utilize multiple devices to counteract uncertain voltage fluctuation and deviation. In the hourly timescale (first stage), capacitor banks and transformer tap changers are scheduled before stochastic renewable output and load variations are realized. In the 15-min timescale (second stage), inverters that interface the renewable energy resources provide var support to supplement the first-stage decision after uncertainty is observed. The coordination is model as a two-stage stochastic programming problem with scenario reduction. It is then converted to a deterministic mixed-integer quadratic programming equivalence model and solved by commercial solvers combined. Compared with existing methods, the proposed volt/var control can achieve lower expected energy loss and can sustain a secure voltage level under random load demand and renewable power injection. The proposed method is verified on the IEEE 33-bus distribution network and compared with existing practices.
Autors: Yan Xu;Zhao Yang Dong;Rui Zhang;David J. Hill;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4398 - 4408
Publisher: IEEE
 
» Multi-User Massive MIMO Relay Networks With Space-Constrained 2-D Antenna Arrays
Abstract:
The detrimental effects of spatially correlated fading are investigated for multi-user massive multiple-input multiple-output relay networks with maximal-ratio combining detectors. To this end, the achievable sum rates are derived in closed form for quantifying the cumulative effects of: 1) imperfect channel state information and 2) spatially correlated fading at the co-located space-constrained 2-D antenna arrays with increasingly many antenna elements for 3-D fading channels. The achievable sum rate for the uncorrelated fading and the corresponding asymptotic sum rate limit are derived. Our results reveal that the correlated fading in 2-D antenna arrays significantly degrades the achievable sum rate even in the finite antenna regime. The sum rate loss gradually increases, and hence, the achievable sum rate becomes infinitesimal in the asymptotic regime of 2-D antenna arrays with finite dimensions over 3-D correlated fading channels.
Autors: Dhanushka Priyankara Kudathanthirige;Gayan Amarasuriya Aruma Baduge;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2540 - 2543
Publisher: IEEE
 
» Multiband Balanced Filters With Controllable Bandwidths Based on Slotline Coupling Feed
Abstract:
Novel multiband balanced bandpass filters with controllable bandwidths are presented in this letter. Slotline coupled-feed structure (SLCFS) is employed to suppress the common mode (CM), due to its intrinsic CM rejection. For differential mode, the tri-band/quad-band performance is realized by three/four pairsofhalf-wavelength resonators, which are designed for different passbands, respectively. Since the load effects between different resonators are very slight, the passband frequencies and bandwidths can be independently tuned and designed. Moreover, quasi-elliptical bandpass responses could be achieved to enhance the selectivity. Finally, two multiband balanced filters are designed and fabricated to validate the design method. To the best of authors’ knowledge, the quad-band balanced filter may be the first ever reported.
Autors: Shi-Xuan Zhang;Lei-Lei Qiu;Qing-Xin Chu;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Nov 2017, volume: 27, issue:11, pages: 974 - 976
Publisher: IEEE
 
» Multicast Scheduling for Relay-Based Heterogeneous Networks Using Rateless Codes
Abstract:
We consider the multicast scheduling problem in the heterogeneous network using a half-duplex relay station (RS). Our goal is to minimize the delay of transmitting a block of packets to users over time-varying channels using rateless codes. Due to half-duplex operation, at each time slot, the RS can choose to either multicast a packet to the users, or fetch a packet from the macro base station. We formulate a fluid relaxation for the optimal decision problem, and reveal that the optimal policy has a threshold-based structure so as to exploit the opportunism of multicast channel: the RS should multicast only when the channel quality is sufficiently “high”. We propose an online policy based on the relaxation which does not require the knowledge of channel distribution. When the channel distribution is symmetric across users, we provide a closed-form expression of the asymptotic performance of our policy. For two-user systems, we prove that our scheme is asymptotically optimal. When the users’ channels are independent, we derive a performance bound based on water-filling rate allocation which approximates the optimal policy well. Simulation results show that our scheme performs close to theoretical bounds, under correlated as well as independent fading channels.
Autors: Chao Chen;Seung Jun Baek;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Nov 2017, volume: 16, issue:11, pages: 3142 - 3155
Publisher: IEEE
 
» Multicast techniques for hybrid RF/FSO DTNs
Abstract:
Increasing the contact bandwidth in delay tolerant networks (DTNs) via multicopy routing leads to a decrease in data delivery delay and an improvement in throughput. In DTNs, in which nodes have both radio frequency (RF) and free space optical (FSO) PHY layers, contact bandwidth can be increased by using the FSO PHY as the data channel and performing multicasting. As we show in this paper, due to the highly directional nature of FSO, a naïve broadcast strategy where the beam divergence includes all nodes in the broadcast set, it does not always result in the minimization of data delivery delay and the maximization of delivery probability. To this end, we develop multicast strategies for hybrid RF/FSO DTNs via an emulation of static conditions in mobile DTNs in which RF is primarily used for control. We show that the optimal multicast problem in static environments is an abstraction of the minimum weighted set cover problem, which is known to be NP-hard. To save on computation time, we propose a greedy local optimum heuristic. Performance of the various multicast techniques is comprehensively evaluated in a DTN simulator, using the Epidemic routing protocol. These evaluations show that our computationally cheap solution yields results identical to optimal while not compromising the performance of the DTN.
Autors: M. Atakora;H. Chenji;
Appeared in: IEEE/OSA Journal of Optical Communications and Networking
Publication date: Nov 2017, volume: 9, issue:11, pages: 1051 - 1061
Publisher: IEEE
 
» Multicriteria Green Supplier Segmentation
Abstract:
Supplier segmentation is an important strategic activity for companies. The main purpose of segmenting suppliers is to more easily manage a large number of suppliers by formulating relationship management strategies for subsets of suppliers, which is more efficient than separate unique strategies for each supplier. Existing supplier segmentation approaches have paid limited attention to environmentally related criteria. Given the increased importance of sustainable and green supply chains, this points a large gap in the literature. Thus, a green supplier segmentation model is proposed in this study. A supplier potential matrix is used to evaluate suppliers with respect to two dimensions, capabilities and willingness, with respect to environmental issues. Given the multicriteria nature of this problem, a novel hybrid multicriteria methodology is used to evaluate the problem. Rough set theory is used to calculate the weight of each criterion for suppliers’ capabilities and suppliers’ willingness. VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) is then used to determine an overall score for each supplier. Finally, fuzzy C-means is used to segment the suppliers while considering the overall score for each supplier. An application of the proposed model for suppliers of a large chemical company is used to evaluate the feasibility of this technique.
Autors: Chunguang Bai;Jafar Rezaei;Joseph Sarkis;
Appeared in: IEEE Transactions on Engineering Management
Publication date: Nov 2017, volume: 64, issue:4, pages: 515 - 528
Publisher: IEEE
 
» Multifunctional Reconfigurable Filter Using Transversal Signal-Interaction Concepts
Abstract:
A novel multifunctional reconfigurable filter with three different transmission modes using transversal signal-interaction principles is proposed. These three operational modes allow to reconfigure the engineered filtering device as ultra-wideband bandpass filter, narrow-band bandpass filter (NB BPF), and ultra-wideband band-stop filter (UWB BSF). By turning on/off the RF switches, the transmission lines and stubs can be dynamically connected or disconnected so that the three transmission modes can be discretely selected. For the UWB-BPF mode, the 3-dB bandwidth is 95.7% (1.51–4.38 GHz) with minimum in-band insertion loss of 0.94 dB. For the NB-BPF mode, the 3-dB bandwidth is 25.3% (2.55–3.29 GHz), the minimum in-band insertion loss is 0.8 dB, and the stopband rejection is higher than 11.6 dB. For the UWB-BSF mode, the 3-dB bandwidth is 106% (1.41–4.59 GHz) with in-band insertion loss above 10 dB.
Autors: Wenjie Feng;Yuxia Shang;Wenquan Che;Roberto Gómez-García;Quan Xue;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Nov 2017, volume: 27, issue:11, pages: 980 - 982
Publisher: IEEE
 
» Multilevel Converters: Control and Modulation Techniques for Their Operation and Industrial Applications
Abstract:
In the last decades, multilevel converters have been developed usually for medium-voltage high-power applications. They have become a mature solution for the increasing power demand of multiple applications such as renewable energy systems, power quality improvement, and motor drives. In this paper, the operation of multilevel converters is addressed focusing on control and modulation techniques for different well-known applications. The new developments are presented as an extension of conventional methods for two-level voltage-source converters which are still the mainstream solution for most cases.
Autors: Jose I. Leon;Sergio Vazquez;Leopoldo G. Franquelo;
Appeared in: Proceedings of the IEEE
Publication date: Nov 2017, volume: 105, issue:11, pages: 2066 - 2081
Publisher: IEEE
 
» Multilevel Converters: Fundamental Circuits and Systems
Abstract:
This paper provides a chronological overview of the topology for multilevel converters, and discusses their different terminology usages and characteristics. The multilevel converters include three-level neutral-point-clamped (NPC) and neutral-point-piloted (NPP) inverters, three-level and four-level flying-capacitor (FLC) inverters, and a family of modular multilevel cascade converters. Some have already been put into commercial use, some have been on a research and development stage, and others have been on an academic research stage. This paper pays much attention to six family members of the modular multilevel cascade converters, intended for grid-tied applications and medium-voltage high-power motor drives.
Autors: Hirofumi Akagi;
Appeared in: Proceedings of the IEEE
Publication date: Nov 2017, volume: 105, issue:11, pages: 2048 - 2065
Publisher: IEEE
 
» Multilevel Subarray Modularization to Construct Hierarchical Beamforming Networks for Phased Array of Antennas With Low Complexity
Abstract:
A multilevel subarray RF modularization technique is presented to construct a hierarchical beamforming network (BFN) for phased array of antennas. In contrast to the conventional BFN architecture, which feeds each antenna element by using individual set of RF devices, the restructured RF modules may simplify the BFN architecture. They may dramatically reduce the cost without significantly sacrificing the radiation performance. In this technique, the RF devices to feed antenna elements are subdivided into groups for modularization. Each module is formed by very few elements of RF devices to form a multilevel BFN, where the number of RF elements in each module are the integer factors of array size. Each module at the same layer consists of identical RF structures to minimize the mass manufacture cost. In this paper, the theoretical foundation is developed to provide design guidelines. Examination of radiation discrepancy is also investigated to demonstrate the feasibility and validate the proposed technique.
Autors: Hsi-Tseng Chou;Hao-Ju Huang;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 5819 - 5828
Publisher: IEEE
 
» Multimedia Relay Resource Allocation for Energy Efficient Wireless Networks: High-Layer Content Prioritization With Low-Layer Diversity Cooperation
Abstract:
With the popularity of versatile mobile multimedia applications and the pressing need to reduce energy consumption in future wireless networks, new challenges have been posed to maintain adequate coverage, quality of service, and reliability for big-scale multimedia traffic. Specifically, in this paper we introduce a cooperative multimedia relay framework and investigate premium-regular-diversity-based multimedia resource allocation treatment approaches. We also comparatively study five generic wireless multimedia relay scenarios including direct transmission, single relay, multiple pure relays, relay cooperation with space-time coding, and relay coordination with distributed beamforming. The key contribution of the new relay resource allocation framework is that packet importance priority diversity at the application layer is jointly considered with spatial diversity and relay coordination protocols at lower layers. Premium packets and regular packets of multimedia streams are adaptively allocated to relay nodes, and transmission resources are optimally allocated with regards to energy budget. Extensive simulation results demonstrate that the proposed resource allocation paradigm using multirelay coordination has significant video quality enhancement and energy saving potentials to support future big-data wireless multimedia traffic.
Autors: Qin Wang;Wei Wang;Kazem Sohraby;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10394 - 10405
Publisher: IEEE
 
» Multimodal Speech Capture System for Speech Rehabilitation and Learning
Abstract:
Speech-language pathologists (SLPs) are trained to correct articulation of people diagnosed with motor speech disorders by analyzing articulators’ motion and assessing speech outcome while patients speak. To assist SLPs in this task, we are presenting the multimodal speech capture system (MSCS) that records and displays kinematics of key speech articulators, the tongue and lips, along with voice, using unobtrusive methods. Collected speech modalities, tongue motion, lips gestures, and voice are visualized not only in real-time to provide patients with instant feedback but also offline to allow SLPs to perform post-analysis of articulators’ motion, particularly the tongue, with its prominent but hardly visible role in articulation. We describe the MSCS hardware and software components, and demonstrate its basic visualization capabilities by a healthy individual repeating the words “Hello World.” A proof-of-concept prototype has been successfully developed for this purpose, and will be used in future clinical studies to evaluate its potential impact on accelerating speech rehabilitation by enabling patients to speak naturally. Pattern matching algorithms to be applied to the collected data can provide patients with quantitative and objective feedback on their speech performance, unlike current methods that are mostly subjective, and may vary from one SLP to another.
Autors: Nordine Sebkhi;Dhyey Desai;Mohammad Islam;Jun Lu;Kimberly Wilson;Maysam Ghovanloo;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Nov 2017, volume: 64, issue:11, pages: 2639 - 2649
Publisher: IEEE
 
» Multiparty Consensus of Linear Heterogeneous Multiagent Systems
Abstract:
In this paper, we investigate the multiparty output consensus of linear heterogeneous agents, in which the outputs of the agents within a party synchronize to each other, but different parties have different synchronized trajectories. To solve this problem, graphs with complex edge weights are used. We provide a sufficient condition for leader-follower multiparty output consensus of linear heterogeneous agents. We also give a similar sufficient condition for multiparty state consensus of linear homogeneous agents as homogeneous agents could be considered as a special case of heterogeneous agents. As one direct application of our theory, we provide a solution to formation control of linear heterogeneous agents, where the position of each follower agent in the formation is described by two key pieces of information: A fixed orientation of the follower's location with respect to the leader's location (within a given coordinate system), and a time-variant formation constraint (such as the relative distance) between the leader and the follower, which is captured by some linear command generator. We present sufficient conditions for both simultaneous formation and reference trajectory tracking via the internal model principle.
Autors: Farnaz Adib Yaghmaie;Rong Su;Frank L. Lewis;Lihua Xie;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5578 - 5589
Publisher: IEEE
 
» Multipath Clustering and Cluster Tracking for Geometry-Based Stochastic Channel Modeling
Abstract:
This paper presents a clustering and tracking method that exploits the geometry of the scattering points (SPs) obtained from the measurement-based ray tracer. The multipath components (MPCs) were categorized into clusters by applying the KPowerMeans (KPM) framework to those SPs. The clusters were tracked by comparing the cluster-centroid SPs of the adjacent snapshots. The clusters were estimated based on the indoor environment geometry at 11 GHz, and their physical mechanisms were interpreted. The complexity and performance of this method was assessed and compared with that of conventional KPM by comparing the number of floating point operations (FLOPS) and the channel eigenvalues obtained from the reconstructed channel matrices, which were calculated by superposing the MPCs randomly generated from intracluster parameters. The verification of this method showed that most clusters were estimated and tracked according to the physical location of the scatterers in the environment with acceptable error. Moreover, the eigenvalues reconstructed from the proposed method were closer to the measured ones with less number of FLOPS, which indicates both accuracy and complexity improvement. The results also imply that multiple-input multiple-output performance is highly dependent on the radio propagation channel; therefore, it is imperative that clusters in the channel be determined accurately.
Autors: Panawit Hanpinitsak;Kentaro Saito;Jun-ichi Takada;Minseok Kim;Lawrence Materum;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6015 - 6028
Publisher: IEEE
 
» Multiple Event Detection and Recognition for Large-Scale Power Systems Through Cluster-Based Sparse Coding
Abstract:
Accurate event analysis in real time is of paramount importance for high-fidelity situational awareness such that proper actions can take place before any isolated faults escalate to cascading blackouts. Existing approaches are limited to detect only single or double events or a specified event type. Although some previous works can well distinguish multiple events in small-scale systems, the performance tends to degrade dramatically in large-scale systems. In this paper, we focus on multiple event detection, recognition, and temporal localization in large-scale power systems. We discover that there always exist “regions” where the reaction of all buses to certain event within each region demonstrates high degree similarity, and that the boundary of the “regions” generally remains the same regardless of the type of event(s). We further verify that, within each region, this reaction to multiple events can be approximated as a linear combination of reactions to each constituent event. Based on these findings, we propose a novel method, referred to as cluster-based sparse coding (CSC), to extract all the underlying single events involved in a multievent scenario. Multiple events of three typical disturbances (e.g., generator trip, line trip, and load shedding) can be detected and recognized. Specifically, the CSC algorithm can effectively distinguish line trip events from oscillation, which has been a very challenging task for event analysis. Experimental results based on simulated large-scale system model (i.e., NPCC) show that the proposed CSC algorithm presents high detection and recognition rate with low false alarms.
Autors: Yang Song;Wei Wang;Zhifei Zhang;Hairong Qi;Yilu Liu;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4199 - 4210
Publisher: IEEE
 
» Multiple Kernel Learning for Hyperspectral Image Classification: A Review
Abstract:
With the rapid development of spectral imaging techniques, classification of hyperspectral images (HSIs) has attracted great attention in various applications such as land survey and resource monitoring in the field of remote sensing. A key challenge in HSI classification is how to explore effective approaches to fully use the spatial–spectral information provided by the data cube. Multiple kernel learning (MKL) has been successfully applied to HSI classification due to its capacity to handle heterogeneous fusion of both spectral and spatial features. This approach can generate an adaptive kernel as an optimally weighted sum of a few fixed kernels to model a nonlinear data structure. In this way, the difficulty of kernel selection and the limitation of a fixed kernel can be alleviated. Various MKL algorithms have been developed in recent years, such as the general MKL, the subspace MKL, the nonlinear MKL, the sparse MKL, and the ensemble MKL. The goal of this paper is to provide a systematic review of MKL methods, which have been applied to HSI classification. We also analyze and evaluate different MKL algorithms and their respective characteristics in different cases of HSI classification cases. Finally, we discuss the future direction and trends of research in this area.
Autors: Yanfeng Gu;Jocelyn Chanussot;Xiuping Jia;Jón Atli Benediktsson;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6547 - 6565
Publisher: IEEE
 
» Multiscale Hydraulic Fracture Modeling With Discontinuous Galerkin Frequency-Domain Method and Impedance Transition Boundary Condition
Abstract:
To facilitate the detection of hydraulic fractures by electromagnetic survey, a discontinuous Galerkin frequency-domain (DGFD) method is introduced in this paper to efficiently model the fracture responses under complicated geophysical environments. In the proposed DGFD method, the computational domain can be split into multiple subdomains with nonconformal meshes. The Riemann solver (upwind flux) is introduced to evaluate the numerical flux. The impedance transition boundary condition (ITBC) is employed to facilitate fracture modeling by approximating fractures as surfaces. Numerical results show that the ITBC works well for different fracture conductivities, dipping angles, operation frequencies, as well as different sources. For both small- and large-scale fractures, it also shows good agreement with the references. The responses of fractures increase as their conductivities become larger. Large dipping angles can cause spikes on the responses in a borehole. For a magnetic source, higher operation frequencies can enhance the signal level, while for an electric source, the sensitivity to frequency is small. When no borehole is considered, the responses due to an electric source are in general larger than those due to a magnetic one. However, when a borehole with conductive mud is included, the responses can be reversed for the electric and magnetic sources. For multiple fractures outside a cased borehole, the signal level of an electric source is significantly reduced, while that of a magnetic source remains at a similar level compared with the scenario without a casing. With the proposed technique, multiscale modeling of hydraulic fractures in complicated geophysical environments becomes possible.
Autors: Qingtao Sun;Runren Zhang;Qiwei Zhan;Qing Huo Liu;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6566 - 6573
Publisher: IEEE
 
» Multiscale Superpixel-Level Subspace-Based Support Vector Machines for Hyperspectral Image Classification
Abstract:
This letter introduces a new spectral–spatial classification method for hyperspectral images. A multiscale superpixel segmentation is first used to model the distribution of classes based on spatial information. In this context, the original hyperspectral image is integrated with segmentation maps via a feature fusion process in different scales such that the pixel-level data can be represented by multiscale superpixel-level (MSP) data sets. Then, a subspace-based support vector machine (SVMsub) is adopted to obtain the classification maps with multiscale inputs. Finally, the classification result is achieved via a decision fusion process. The resulting method, called MSP-SVMsub, makes use of the spatial and spectral coherences, and contributes to better feature characterization. Experimental results based on two real hyperspectral data sets indicate that the MSP-SVMsub exhibits good performance compared with other related methods.
Autors: Haoyang Yu;Lianru Gao;Wenzhi Liao;Bing Zhang;Aleksandra Pižurica;Wilfried Philips;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2142 - 2146
Publisher: IEEE
 

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