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

» Hierarchical SCOPF Considering Wind Energy Integration Through Multiterminal VSC-HVDC Grids
Abstract:
In this paper, a hierarchical security-constrained optimal power flow (SCOPF) model is proposed for a meshed ac/multiterminal HVDC (MTDC) system with high wind penetration. The two interacting levels in the proposed model are as follows: 1) the high level is a traditional SCOPF problem in an ac system that aims to minimize total generation and security control costs; and 2) the low level is a dynamic power dispatching problem, which regulates power flow in an MTDC grid according to reference signals from the high level. Thus, the proposed method utilizes an MTDC system to provide support for the ac system by redistributing power flow across the entire grid and reducing control costs. Two modified IEEE meshed ac/dc systems are used to demonstrate the performance of the proposed method.
Autors: Ke Meng;Wang Zhang;Yujun Li;Zhao Yang Dong;Zhao Xu;Kit Po Wong;Yu Zheng;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4211 - 4221
Publisher: IEEE
 
» Hierarchical Subspace Learning Based Unsupervised Domain Adaptation for Cross-Domain Classification of Remote Sensing Images
Abstract:
We address the problem of automatic updating of land-cover maps by using remote sensing images under the notion of domain adaptation (DA) in this paper. Essentially, unsupervised DA techniques aim at adapting a classifier modeled on the source domain by considering the available ground truth and evaluate the same on a related yet diverse target domain consisting only of test samples. Traditional subspace learning based strategies in this respect inherently assume the existence of a single subspace spanning the data from both the domains. However, such a constraint becomes rigid in many scenarios considering the diversity in the statistical properties of the underlying semantic classes and problem due to data overlapping in the feature space. As a remedy, we propose an automated binary-tree based hierarchical organization of the semantic classes and subsequently introduce the notion of node-specific subspace learning from the learned tree. We validate the method on hyperspectral, medium-resolution, and very high resolution datasets, which exhibits a consistently improved performance in comparison to standard single subspace learning based strategies as well as other representative techniques from the literature.
Autors: Biplab Banerjee;Subhasis Chaudhuri;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 5099 - 5109
Publisher: IEEE
 
» High Performance Single Element MI Magnetometer With Peak-to-Peak Voltage Detector by Synchronized Switching
Abstract:
We propose a new high performance magnetometer using a single magneto-impedance (MI) sensor with a peak-to-peak voltage detector by synchronized switching (shortened: Pk-pk VD-type MI magnetometer), which is aimed to measure an extremely weak magnetic field ranging from nT ( T) to pT ( T), based upon the conventional MI magnetometer, which is used in the electronic compass. In order to enhance sensitivity and reduce noise, the Pk-pk VD-type MI magnetometer detects both the positive peak and the negative peak in induced voltage waveform of pickup coil. In this paper, for demonstrating the performances of the Pk-pk VD-type MI magnetometer, we investigate the magnetic field sensitivity and the magnetic noise spectral density. We demonstrated that the noise level of the Pk-pk VD-type MI magnetometer is lower than 2 pT/Hz for the frequency range from 1 to 100 Hz, which is much better than the conventional MI magnetometer. We discuss the noise performance of the Pk-pk VD-type MI magnetometer. According to the results obtained in this paper, we expect that this proposed MI magnetometer can be widely used for extremely weak magnetic field detection.
Autors: Jiaju Ma;Tsuyoshi Uchiyama;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» High Tunnel Magnetoresistance in Mo/CoFe/MgO Magnetic Tunnel Junction: A First-Principles Study
Abstract:
The tunnel magnetoresistance (TMR) ratio in a magnetic tunnel junction (MTJ) is influenced by heavy metal capping layer due to the interfacial effect. We report a systematic first-principles study on MTJ based on CoFe/MgO with capping layer, demonstrate that TMR ratios are sensitive to capping layer material, and show that TMR in Mo-capped MTJ is three times as high as that in Ta-capped MTJ. Besides, TMR in Mo-capped MTJ remains high at finite voltage bias. By analyzing the transmission spectrum and density of scattering states, we found that coherent transmission of state dominates the majority-spin conductance in Mo-capped MTJ, while the resonant tunneling contributes significantly in Ta-capped MTJ. The evolution of TMR for varying MgO and CoFe thickness in Mo-capped MTJ is presented. TMR oscillates as a function of CoFe thickness because of the confined wave function in ferromagnetic layer, while TMR rises with MgO thickness increasing due to the enhanced filtering effect of MgO. This work clarifies the physical mechanism on high TMR in Mo-capped MTJ, which is promising to benefit the design of spintronics device.
Autors: Jiaqi Zhou;Weisheng Zhao;Shouzhong Peng;Junfeng Qiao;Jacques-Olivier Klein;Xiaoyang Lin;Youguang Zhang;Arnaud Bournel;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» High-Accuracy Subpixel Image Registration With Large Displacements
Abstract:
This paper aims to achieve computationally efficient and high-accuracy subpixel image registration with large displacements under the rotation–scale–translation model. This paper employs the classical phase correlation algorithm and the Lucas–Kanade (LK) algorithm in a two-stage coarse-to-fine framework, for which the motivation is from the observation that the two algorithms exhibit strong complementary property between convergence range and subpixel accuracy. In this framework, the LK algorithm will also become computationally efficient owing to the small residual displacement. On the other hand, this paper takes into account the residual model with respect to the compensation scheme explicitly, and deduces formulas for the final results combination, which is expected to be closer to the true displacement vector and thus further improve the estimation accuracy. Since the compensation can be applied to either the target image or the reference image, two algorithms are presented accordingly, and analysis as well as comparison are also performed. Finally, both simulations and real image experiments are performed to verify the motivation, and the results are consistent with the analysis.
Autors: Xiangguo Li;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6265 - 6276
Publisher: IEEE
 
» High-Density Shingled Heat-Assisted Recording Using Bit-Patterned Media Subject to Track Misregistration
Abstract:
Shingled recording employing bit-patterned media when used in conjunction with heat-assisted magnetic recording can significantly enhance the recording density. This paper investigates writing of dots that are not directly under the laser pulse. Such a shifted scheme of writing allows higher densities when used with shingled recording. A further increase in the recording density can be obtained by using composite structures, comprising a superparamagnetic writing layer, and a (doped) FePt storage layer. Effect of head velocity, Curie temperature variation, track mis-registration, and dot position jitter on the standard deviation of switching distribution is studied to evaluate the designs that offer data densities as high as ~16 Tbpsi.
Autors: Aneesh Venugopal;Ali Ghoreyeshi;R. H Victora;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» High-Dimensional Pixel Composites From Earth Observation Time Series
Abstract:
High-quality and large-scale image composites are increasingly important for a variety of applications. Yet a number of challenges still exist in the generation of composites with certain desirable qualities such as maintaining the spectral relationship between bands, reduced spatial noise, and consistency across scene boundaries so that large mosaics can be generated. We present a new method for generating pixel-based composite mosaics that achieves these goals. The method, based on a high-dimensional statistic called the ‘geometric median,’ effectively trades a temporal stack of poor quality observations for a single high-quality pixel composite with reduced spatial noise. The method requires no parameters or expert-defined rules. We quantitatively assess its strengths by benchmarking it against two other pixel-based compositing approaches over Tasmania, which is one of the most challenging locations in Australia for obtaining cloud-free imagery.
Autors: Dale Roberts;Norman Mueller;Alexis Mcintyre;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6254 - 6264
Publisher: IEEE
 
» High-Efficiency Microwave Rectifier With Less Sensitivity to Input Power Variation
Abstract:
In this letter, a novel microwave rectifier based on a power recycling network (PRN) is proposed, which features less sensitivity to input power variation. The PRN is connected to the microwave input of two parallel subrectifiers, realizing better matching over a wide power range. For validation, a 2.45-GHz rectifier incorporating the PRN is designed and implemented. The measured results show that the RF-dc conversion efficiency maintains over 50% and 70% within the input power range 10.5–31.8 and 21.7–30.1 dBm, respectively. Compared with the counterpart without the PRN, the operating power range is extended without degrading the maximum efficiency.
Autors: Zhi-Xia Du;Xiu Yin Zhang;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Nov 2017, volume: 27, issue:11, pages: 1001 - 1003
Publisher: IEEE
 
» High-Frequency Magnetic Thin-Film Inductor Integrated on Flexible Organic Substrates
Abstract:
This paper presents integrated inductors with Co-Zr-Ta-B (CZTB) thin films on flexible organic substrates for MHz–GHz applications. This paper demonstrated the fabrication and characterization of magnetic thin-film inductors on flexible organic substrates, such as polyimide and Ajinomoto build-up film thin films. These films have thicknesses of only tens of micrometer and thus are very flexible compared to the same inductor structures fabricated on rigid substrates, such as quartz. The magnetic films on flexible substrates were observed to maintain similar magnetic properties compared with those on Si substrate, but with greater coercivity likely due to the increased roughness of the substrate surface. The fabricated thin-film inductors on organic substrates with inductance , measured by RF characteristics, have shown significantly increased inductance compared to air-core inductors (without magnetic core materials). This paper also demonstrated a high frequency response, clearly over GHz, consistent with the CZTB type of materials. The frequency response, as well as inductance and Q values, remains similar even after many iterations of bending to a large degree, indicating the robustness of the inductor on flexible organic substrates, as well as that of the magnetic thin films.
Autors: Hao Wu;Mahmoud Khdour;Priyanka Apsangi;Hongbin Yu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 7
Publisher: IEEE
 
» High-Frequency Properties of Fe-4.5 Wt% Si Powders With an Insulating Layer Synthesized by a Modified Dew-Point Treatment
Abstract:
The frequency for wireless power chargers is in the range of 100–205 kHz when using MnZn ferrite and NiZn ferrite. Compared to ferromagnetic metals, these ferrites have higher resistivity, which reduces the eddy loss at high frequencies, though they also have lower magnetization values that limit the distance and the direction between the receiver and transmitter units. Thus, there is a strong demand for the development of a new metallic magnetic sheet that can suppress the eddy-current loss in the high-frequency range. To meet this demand, a modified dew-point insulation coating method for Fe-4.5 wt% Si powders was assessed and the high-frequency properties of green compacts consisting of these powders were investigated. As a result, a thin high-resistivity layer was successfully coated onto the powders. In addition, both eddy-current loss and hysteresis loss of their compacts were dramatically reduced in the high-frequency region.
Autors: Kwiyoung Lee;Moosung Choi;Jongryoul Kim;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» High-Performance GaN-Based LEDs on Si Substrates: The Utility of Ex Situ Low-Temperature AlN Template With Optimal Thickness
Abstract:
Ex situ low-temperature (LT)-AlN templates are employed to realize GaN-based light-emitting diodes (LEDs) on Si substrates by the combination of pulsed laser deposition and metal organic chemical vapor deposition. The influence of ex situ LT-AlN template thickness on the properties and performance of as-grown LEDs has been carefully studied. The LED wafer grown on 70-nm-thick ex situ LT-AlN template exhibits a crack-free surface, good crystalline quality, and excellent multiple quantum wells (MQWs) structural property. The LED chips fabricated with lateral structure show the highest light output power of 70.2 mW at an injection current of 300 mA. Through optimizing the thickness of ex situ LT-AlN template, the light output power is greatly improved by 39%. Theoretical analysis has been taken to study the enhancement mechanism of luminous intensity in this LED. It reveals that the residual stress in as-grown wafers is significant to enhance the luminescence of LEDs. The largest residual tensile stress in the LED presents great potential to enhance the carrier injection and transportation, increase the carrier concentrations, and improve the radiative recombination intensity in MQWs, which is crucial to improve the luminous intensity of LEDs.
Autors: Haiyan Wang;Zhiting Lin;Yunhao Lin;Wenliang Wang;Guoqiang Li;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4540 - 4546
Publisher: IEEE
 
» High-Performance Single-Electron Transistor Based on Metal–Organic Complex of Thiophene: First Principle Study
Abstract:
The ab initio perspective based on density functional theory and nonequilibrium Green’s function for the modeling of single electron transistors (SETs) based on thiol-ended thiophene and chromium complex of thiol-ended thiophene and their functioning in the Coulomb blockade regime has been discussed. Both thiol-ended thiophene molecule and its chromium complex have been analyzed for the charge stability and conductance dependence on the gate voltage and source–drain bias. The charging energies for the isolated and SET environment for both the islands have been calculated and discussed. Also, the effect of orientation and the dielectric medium has been studied in order to increase the conductance of SET with the combination of a particular orientation and a dielectric medium. The effect of different electrodes on charge stability diagram has also been studied. The analysis shows a remarkably improved conductance for the chromium complex of thiol-ended thiophene molecule in the SET environment than the thiol-ended thiophene molecule in the SET environment resulting in a fast switching metal–organic SET.
Autors: Anu;Archana Sharma;Md. Shahzad Khan;Anurag Srivastava;Mushahid Husain;Mohd. Shahid Khan;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4628 - 4635
Publisher: IEEE
 
» High-Power Evanescently Coupled Waveguide MUTC Photodiode With >105-GHz Bandwidth
Abstract:
We demonstrate high-speed and high-power evanescently coupled waveguide integrated modified unitraveling carrier photodiodes. Over 105-GHz bandwidth along with 2 and 1.3 dBm RF output power at 100 and 105 GHz, respectively, has been achieved.
Autors: Qinglong Li;Keye Sun;Kejia Li;Qianhuan Yu;Patrick Runge;Willi Ebert;Andreas Beling;Joe C. Campbell;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4752 - 4757
Publisher: IEEE
 
» High-Precision Resolver-to-Velocity Converter
Abstract:
Accurate velocity estimation for rotary control over a large velocity range has been a challenge. In this paper, we propose a virtually analog resolver-to-velocity converter that applies trigonometric transformations to the resolver outputs. We also present hardware that extends the output range of a previously proposed resolver-to-position circuit from 90° to 360°. The position and velocity outputs of the two circuits are evaluated against the position and velocity obtained from an optical encoder using the backward difference differentiation technique. Recommendations for tuning and improvements in the circuitry are also provided.
Autors: Leonam Pecly;Ryan Schindeler;Daniel Cleveland;Keyvan Hashtrudi-Zaad;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2917 - 2928
Publisher: IEEE
 
» High-Precision, Mixed-Signal Mismatch Measurement of Metal–Oxide–Metal Capacitors
Abstract:
This brief presents a high-precision, mixed-signal mismatch measurement technique for metal–oxide–metal capacitors. The proposed technique incorporates a switched-capacitor op amp within the measurement circuit to significantly improve the measurement precision while relaxing the resolution requirement on the backend analog-to-digital converter (ADC). The proposed technique is also robust against multiple types of errors. A detailed analysis is presented to quantify the sensitivity improvement of the proposed technique over the conventional one. In addition, this brief proposes a multiplexing technique to measure a large number of capacitors in a single chip and a new layout to improve matching. A prototype fabricated in 180 nm technology demonstrates the ability to sense capacitor mismatch standard deviation as low as 0.045% with excellent repeatability, all without the need of a high-resolution ADC.
Autors: Danilo Bustamante;Devon Janke;Eric Swindlehurst;Shiuh-Hua Wood Chiang;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Nov 2017, volume: 64, issue:11, pages: 1272 - 1276
Publisher: IEEE
 
» High-Resolution Microwave Breast Imaging Using a 3-D Inverse Scattering Algorithm With a Variable-Strength Spatial Prior Constraint
Abstract:
Microwave inverse scattering is an exploratory imaging modality with potential for several clinical breast imaging applications, including density evaluation, cancer detection, and treatment monitoring. However, conventional regularization techniques used to solve the ill-posed inverse problem typically result in blurred boundaries between tissue structures exhibiting dielectric contrast, thereby limiting the effective resolution. We present a method to improve microwave breast imaging resolution that incorporates a priori information about the boundaries between different tissues in the breast into the inverse scattering algorithm. This spatial prior information can be derived from another imaging modality, such as magnetic resonance imaging. Our method exploits the fact that the dielectric properties within a tissue type exhibit low to moderate variability by favoring solutions to the inverse scattering problem, which have small variations in dielectric properties within each tissue region. The amount of variation tolerated in each regions is controlled by a spatial prior constraint parameter. We demonstrate the feasibility of the method by imaging detailed, anatomically inspired numerical 3-D breast phantoms. The performance in the presence of different levels of noise and for different choices of the constraint parameter is evaluated. We also demonstrate the robustness of the algorithm with respect to errors in the spatial prior information.
Autors: Luz Maria Neira;Barry D. Van Veen;Susan C. Hagness;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6002 - 6014
Publisher: IEEE
 
» High-Resolution Parameter Estimation for Time-Varying Double Directional V2V Channel
Abstract:
This paper describes a high-resolution parameter estimation algorithm applied to the vehicle-to-vehicle (V2V) multi-dimensional channel measurements. The algorithm, which is based on a maximum likelihood estimator, jointly estimates parameters of multipath components, such as time-of-arrival, direction of departure, direction of arrival, and Doppler shift. It serves to provide a comprehensive understanding of the V2V propagation channel. We propose computationally attractive methods to initialize parameters in the global search and evaluate key components in the local optimization. We also apply the algorithm to actual V2V channel measurement data. The results suggest an overall good performance of the estimator, where 80% of the snapshots have a diffuse power ratio less than 20% and the dominant specular paths match well with the environment and dynamics of the measurement.
Autors: Rui Wang;Olivier Renaudin;C. Umit Bas;Seun Sangodoyin;Andreas F. Molisch;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7264 - 7275
Publisher: IEEE
 
» High-Resolution Simultaneous Measurement of Strain and Temperature Using $pi$-Phase-Shifted FBG in Polarization Maintaining Fiber
Abstract:
We present a high-resolution simultaneous strain and temperature measurement scheme using -phase-shifted fiber Bragg grating written in PANDA-type polarization maintaining fiber. Two optical parameters, the Bragg frequency and the birefringence-introduced frequency difference, are measured to perform the discrimination of strain and temperature. A double-sideband interrogation method together with a cross-feedback technique is introduced, which significantly reduces the measurement error in birefringence-introduced frequency difference, and hence improves the sensing resolution of strain and temperature. In the demonstration experiment, simultaneous measurement of strain and temperature with resolutions of 0.018 and 0.0014 C respectively is realized.
Autors: Jiageng Chen;Qingwen Liu;Zuyuan He;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:22, pages: 4838 - 4844
Publisher: IEEE
 
» High-Response Identifiable Gas Sensor Based on a Gas-Dielectric ZnPc Nanobelt FET
Abstract:
Gas sensors based on organic semiconductor have recently attracted much attention due to their inherent advantages, especially excellent flexibility and good selectivity. However, the gas species identification with high sensing response remains a key subject for organic gas sensors. Herein, a ZnPc single nanobelt field-effect transistor with the gas dielectric was fabricated and exhibited excellent gas sensing performance at room temperature. The sensors show the high response with 220% to 10 ppm NO2 and 3566% to 20 ppm H2S, and the low detection limit down to 50 ppb towards NO2/H2S, which surpass most reported room-temperature organic-based NO2/H2S sensors. Further, our single device realized accurate gas selective identification among NO2, SO2 and H2S with 92% success ratio in LDA feature space.
Autors: Zhiqi Song;Qingxin Tang;Yanhong Tong;Yichun Liu;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1586 - 1589
Publisher: IEEE
 
» Higher Density Melt Spun Isotropic Magnets
Abstract:
Traditional techniques for consolidating melt spun RE–Fe–B powders tend to incur significant volumes of non-magnetic material, like porosity and the polymer binder. Several alternative consolidation techniques are being studied in an effort to reduce the non-magnetic component and improve the overall performance of such magnets. Rapid electric discharge sintering (REDS) offers one method of fully densifying melt spun RE–Fe–B flakes in a rapid and efficient way with minimal material wastage. This paper attempted to consolidate stoichiometric RE2Fe14B, RE-lean and RE-rich compositions with REDS, spark plasma sintering and conventional hot-tool techniques. The relative magnetic performance and physical condition of the samples are compared. The success of a consolidation technique depends on the melt spun RE–Fe–B chemistry, the relative density of the final compact, and the ability to avoid excessive grain growth in the magnet microstructure.
Autors: Badrinath Veluri;David Brown;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Highly Birefringent Terahertz Waveguide Formed With Dual-Subwavelength Polymer Wires
Abstract:
We propose a highly birefringent terahertz (THz) waveguide, which is formed with two touching subwavelength polymer wires. The waveguide can provide a high modal birefringence larger than 0.01 over a wide frequency range, and a maximum birefringence up to 0.0525 is achieved when the waveguide is made of Topas. Different from other THz birefringent waveguides, a simple scaling rule exists for the proposed birefringent waveguide so that the waveguide can be designed easily for any desired operation frequency to obtain the maximum birefringence. Moreover, when the maximum birefringence takes place, a high coupling efficiency of 93%, a low absorption loss of 0.04 and 0.03 cm-1 for x- and y-polarizations, and a negligible bending loss are demonstrated in our simulations. Finally, the influence of material index is further examined. It is found that as the refractive index of the waveguide material increases, the magnitude of birefringence increases as well, while the frequency at which the maximum birefringence occurs will shift toward the lower region.
Autors: Chih-Hsien Lai;Zong-Sheng Xu;Hsuan-Yu Chen;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4641 - 4649
Publisher: IEEE
 
» Highly Sensitive Acetone Sensor Based on Pd/AlGaN/GaN Resistive Device Grown by Plasma-Assisted Molecular Beam Epitaxy
Abstract:
Highly sensitive acetone sensing performance of Pd/AlGaN/GaN resistive devices in the temperature range of 100 °C–250 °C and in the detection range of 100–1000 ppm was reported. A plasma-assisted molecular beam epitaxy was used to grow the AlGaN/GaN heterostructure on Si (111) substrate. Structural characterization of the grown epilayers was performed through double-crystal X-ray diffraction whereas atomic force microscopy was used to obtain the roughness of the sensing surface. Resistive mode configuration of the sample was tested toward acetone in the detection range of 100–1000 ppm and in the temperature range of 100 °C–250 °C. The optimum temperature was found to be 150 °C with response magnitude ~95% for the acetone concentration of 1000 ppm. The sensor response time and recovery time were found to be in the range of ~18–44 s and ~25–109 s, respectively. The cross-sensitivity of the device with other interfering species such as butanone, benzene, toluene, and xylene attributed to good acetone selectivity of the devices. Acetone sensing as well as current transport of the Pd/AlGaN/GaN devices was illustrated with effect including Langmuir adsorption–desorption kinetics and Schottky barrier height between Pd/AlGaN interfaces.
Autors: Subhashis Das;Saptarsi Ghosh;Rahul Kumar;Ankush Bag;Dhrubes Biswas;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4650 - 4656
Publisher: IEEE
 
» Highly Sensitive ppb Level Methanol Sensor by Tuning C:O Ratio of rGO-TiO2 Nanotube Hybrid Structure
Abstract:
In this paper, ppb level methanol sensing by a hybrid gas sensor device based on reduced graphene oxide (rGO) and TiO2 nanotubes is reported. Tuning of carbon to oxygen ratio, in rGO layers, was found to be very effective in modulating the sensor response. The C:O ratio was tuned by varying the voltage (11–31 V) during the electro-deposition of rGO (on top of the TiO2 nanotube matrix) and was confirmed by Raman spectroscopy and X-ray photoelectron spectroscopy. Due to variations in the C:O ratio in rGO, the barrier height of rGO-TiO2 nanotube junctions and etch hole dimension on rGO layer were varied. Judicious optimization of these two pivotal parameters resulted in the sensor device (for rGO deposition voltage of 16 V), capable of detecting ppb level (up to 62 ppb) methanol efficiently. The sensor showed ∼16%, ∼59%, and ∼94% response magnitude for 62 ppb, 1 ppm, and 200 ppm concentrations, respectively. A comprehensive discussion elucidating the role of rGO-TiO2 NTs junctions (with a tunable C:O ratio) has also been presented correlating the experimental findings.
Autors: Debanjan Acharyya;Snehanjan Acharyya;Kuoyou Huang;Peifang Chung;Monshu Ho;Partha Bhattacharyya;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 1122 - 1128
Publisher: IEEE
 
» HIRAD Brightness Temperature Image Geolocation Validation
Abstract:
The Hurricane Imaging Radiometer (HIRAD) is an airborne microwave radiometer developed to provide wide-swath hurricane surface wind speed and rain rate imagery for scientific research. This letter presents a geometric evaluation of the brightness temperature (Tb) images produced by HIRAD for high-contrast land/water targets. Methodologies used to validate geolocation accuracy and spatial resolution are discussed, and results are presented to provide quantitative pixel geolocation accuracy and the effective image spatial resolution of the Tb image.
Autors: Saleem Sahawneh;W. Linwood Jones;Sayak K. Biswas;Daniel Cecil;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1908 - 1912
Publisher: IEEE
 
» HL-PCM: MLC PCM Main Memory with Accelerated Read
Abstract:
Multi-Level Cell Phase Change Memory (MLC PCM) is a promising candidate technology for DRAM replacement in main memory of modern computers. Despite of its high density and low power advantages, this technology seriously suffers from slow read and write operations. While prior works extensively studied the problem of slow write, this paper targets high read latency problem in MLC PCM and introduces an architecture mechanism to overcome it. To this end, we rely on the fact that reading different bits from an MLC cell takes different latencies, i.e., for a 2-bit MLC, reading its Most-Significant Bit (MSB) is fast, while reading its Least-Significant Bits (LSBs) is slower. We then propose Half-Line PCM (HL-PCM), a novel memory architecture that leverages this non-uniformity in reading MLC PCM’s content to send a requested memory block to the processor in different cycles–it sends half of a memory block to the processor ahead of the other half. If the processor requested a word belonging to the first half, it can resume its execution on receiving the first half, while the other half has not sent yet and scheduled to be received by the memory controller later. HL-PCM is easy and simple to implement, i.e., it needs minor modifications at memory controller, the search/evict policies at last level cache, as well as data layout in main memory. Our experimental results show that the proposed design improves the average memory access latency by 33–43 percent and program’s execution time by 23 percent, on average, while incurring negligible overhead at memory controller and PCM DIMM, in a 16-core chip multiprocessor (CMP) running memory-intensive benchmarks.
Autors: Mohammad Arjomand;Amin Jadidi;Mahmut T. Kandemir;Anand Sivasubramaniam;Chita R. Das;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Nov 2017, volume: 28, issue:11, pages: 3188 - 3200
Publisher: IEEE
 
» Holomorphic Embedding Load-Flow Modeling of Thyristor-Based FACTS Controllers
Abstract:
Development of appropriate load flow model of Flexible AC Transmission System (FACTS) devices is an important issue for proper planning, control, and protection of power system. Holomorphic Embedding Load-Flow Method (HELM) is a novel technique for solving load flow nonlinear equations which overcomes the numerical problems faced by traditional iterative techniques. In order to evaluate the effects of FACTS devices in load flow problem by HELM technique, it is necessary to develop HELM modeling of these devices. This paper presents HELM modeling of Thyristor-based FACTS controllers, i.e., Static Var Compensator (SVC), Thyristor Controlled Switched Capacitor (TCSC), Thyristor Controlled Voltage Regulator (TCVR), and Thyristor Controlled Phase Angle Regulator (TCPAR). In this modeling, white germ solution is investigated along with recursive formula and controlling FACTS devices operation bounds.
Autors: Mohsen Basiri-Kejani;Eskandar Gholipour;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4871 - 4879
Publisher: IEEE
 
» Homogenization of Bi-Isotropic Multilayered Metamaterial Structures
Abstract:
In this paper, we present new expressions of the effective constitutive parameters of bi-isotropic multilayered structure having an arbitrary number of layers and different thicknesses. The present method uses the decomposition scheme, and the commutativity between the homogenization process and the decomposition scheme is supposed. The effective constitutive parameters of the initial structure are evaluated as a function of the two equivalent media's parameters. In order to validate the proposed analytical expressions, the numerical results are compared to the homogenization's multiscale method.
Autors: Ouail Ouchetto;Brahim Essakhi;Saïd Jai-Andaloussi;Saad Zaamoun;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 946 - 953
Publisher: IEEE
 
» Homogenization of the Spatial Sensitivity of Electrostatic Sensors for the Flow Measurement of Pneumatically Conveyed Solids in a Square-Shaped Pipe
Abstract:
The spatial sensitivity of an electrostatic sensor is recognized as an important factor that affects the accuracy of solids flow measurement in a pneumatic conveying pipe. However, the distribution of the spatial sensitivity is generally inhomogeneous due to the physical structure of the electrostatic sensor and the inherent electrostatic sensing mechanism. This paper proposes a sensitivity homogenization method based on differential measurement, i.e., using the differential outputs from two electrodes with different axial widths. The validity of the sensitivity homogenization method for a square-shaped electrostatic sensing head, which consists of strip-shaped electrode arrays with different widths, is validated through mathematical analysis. Furthermore, the response of the electrostatic sensing head incorporating the sensitivity homogenization method to roping flow regimes was evaluated on a gravity-fed solids flow test rig. Results from both modeling and experimental tests indicate that the homogeneity of the spatial sensitivity is improved significantly. The mean non-uniformity of the outputs from the sensing head is 11.7% as a result of the homogenization method.
Autors: Shuai Zhang;Yong Yan;Xiangchen Qian;Rong Huang;Yonghui Hu;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7516 - 7525
Publisher: IEEE
 
» Hot, mobile, and under control [Resources]
Abstract:
When I first learned to solder, I did so using a cheap iron, not realizing how atrocious such things are. It wasn't until several years later that I purchased a temperature-controlled soldering station. These use thermal feedback to keep the tip at a set temperature, and I soon learned that good solder joints are easy to make when you have good equipment. I've had that very same Weller WTCPN soldering station for almost four decades now, having forsaken non-temperature-controlled irons completely. This stance on soldering irons did, however, put me in a quandary recently when I started to explore the options for cordless soldering irons. Cordless irons are essential for those times when you need to solder something and there's no power outlet available. Yet I could not find a cordless iron for sale that had temperature control. So I figured I'd build myself one. My fondness for my faithful Weller soldering station dictated the first design criterion—it had to provide the same quality temperature control—and also suggested a strategy to attain that goal: Weller's Magnastat system. Let me explain. Weller long ago devised a clever way to provide temperature feedback and control without using any electronics. It's based on the physics of ferromagnetic materials, which lose their magnetism when heated above a certain temperature, known as the Curie point. Weller's Magnastat system uses three magnetic components near the tip: two inside a normally open switch, the other built into the tip itself. The components inside the switch (one movable) have a very high Curie point, whereas the one in the tip has a Curie point equal to the desired soldering temperature.
Autors: David Schneider;
Appeared in: IEEE Spectrum
Publication date: Nov 2017, volume: 54, issue:11, pages: 17 - 18
Publisher: IEEE
 
» How Software Is Changing the Automotive Landscape
Abstract:
A look at the creation and distribution of automotive navigation software at TomTom shows how automotive software has changed and might further change.
Autors: Hans Aerts;Han Schaminée;
Appeared in: IEEE Software
Publication date: Nov 2017, volume: 34, issue:6, pages: 7 - 12
Publisher: IEEE
 
» How Statistical Signal Processing Was Used to Define the MH370 Search Zone
Abstract:
Malaysian Airlines flight MH370 from Kuala Lumpur, Malaysia, to Beijing, China, departed on 8 March 2014 carrying 239 passengers and crew. Communications with the aircraft were lost as it transitioned from Malaysian to Vietnamese airspace, and the subsequent search and rescue efforts were unable to find the missing aircraft. Radar data indicates that the aircraft turned to the southwest and crossed Malaysia and then f lew northwest along the Malacca Strait. When the aircraft moved beyond radar coverage, it was still carrying enough fuel to fly for several hours, and the size of the reachable area is almost 20% of the surface of the Earth. Although communications were lost early in flight, there was an active communications link between the aircraft and a satellite; metadata from signaling messages on the link provide information about where the aircraft was, even though no user data was communicated.
Autors: Samuel Davey;Neil Gordon;Ian Holland;Mark Rutten;Jason Williams;
Appeared in: IEEE Potentials
Publication date: Nov 2017, volume: 36, issue:6, pages: 32 - 37
Publisher: IEEE
 
» How to Read Many-Objective Solution Sets in Parallel Coordinates [Educational Forum]
Abstract:
Rapid development of evolutionary algor ithms in handling many-objective optimization problems requires viable methods of visualizing a high-dimensional solution set. The parallel coordinates plot which scales well to high-dimensional data is such a method, and has been frequently used in evolutionary many-objective optimization. However, the parallel coordinates plot is not as straightforward as the classic scatter plot to present the information contained in a solution set. In this paper, we make some observations of the parallel coordinates plot, in terms of comparing the quality of solution sets, understanding the shape and distribution of a solution set, and reflecting the relation between objectives. We hope that these observations could provide some guidelines as to the proper use of the parallel coordinates plot in evolutionary manyobjective optimization.
Autors: Miqing Li;Liangli Zhen;Xin Yao;
Appeared in: IEEE Computational Intelligence Magazine
Publication date: Nov 2017, volume: 12, issue:4, pages: 88 - 100
Publisher: IEEE
 
» HTS Dual-Stator Spoke-Type Linear Vernier Machine for Leakage Flux Reduction
Abstract:
In this paper, a high-temperature superconductor dual-stator spoke-type linear vernier machine (HTS-DSSLVM) is proposed for wave energy extraction, which offers high-thrust force density and better power factor due to leakage flux reduction. HTS bulks are introduced in between the split flux modulation teeth to shield the leakage flux and hence improve the force density and power factor. The electromagnetic characteristics of the machine are comprehensively investigated and compared with that of a recently presented dual-stator spoke-type linear vernier machine (DSSLVM). The results show that the proposed machine yields higher thrust force and better power factor than the DSSLVM due to reduced leakage flux in the proposed machine.
Autors: Noman Baloch;Salman Khaliq;Byung-Il Kwon;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Humidity Sensor Based on Fabry–Perot Interferometer and Intracavity Sensing of Fiber Laser
Abstract:
A humidity sensor based on Fabry–Perot interferometer (FPI) and intracavity sensing of a fiber ring laser is proposed and experimentally demonstrated. A compact humidity-sensitive fiber-optic FPI is developed and inserted in a fiber ring laser. Because the output power of the fiber laser is modulated by the reflection loss of the FPI at different ambient humidity, intracavity humidity sensing is induced. The experiment shows that the relative output power of the fiber laser has a good linear response to ambient humidity from 25%RH to 95%RH and the humidity sensitivity of 0.202 dB/%RH is obtained with a narrow 3-dB bandwidth and high signal-to-noise ratio. Furthermore, the excellent performance of the sensor for remote humidity detection is demonstrated. The sensor also shows a low temperature cross-sensitivity, fast time response, and good stability. The proposed sensor has a great potential in high-capacity sensor network and remote detections.
Autors: Jia Shi;Degang Xu;Wei Xu;Yuye Wang;Chao Yan;Chao Zhang;Dexian Yan;Yixin He;Longhuang Tang;Weihong Zhang;Tiegen Liu;Jianquan Yao;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4789 - 4795
Publisher: IEEE
 
» HVDC Systems in Smart Grids
Abstract:
The use of direct current (dc) power networks, either at high voltage or at medium voltage, is being increasingly seen in modern smart grids. This is due to the flexible control possible with dc and its ability to transmit and distribute power under circumstances where alternating current (ac) networks are either unable to, or less economic. This paper provides an overview of the evolution of high-voltage dc (HVDC) transmission from early Thury systems, to modern ultrahigh-voltage dc and multiterminal voltage–source converter systems. The operation of both current–source and voltage–source systems is discussed, along with modeling requirements. The paper provides a snapshot of the state of the art of HVDC with copious references to enable in-depth reading. Key developments over the last 20 years are highlighted. Issues surrounding multiterminal operation and dc protection are explained, along with drivers in economics and policy. This will inform HVDC integration into smart grids.
Autors: Mike Barnes;Dirk Van Hertem;Simon P. Teeuwsen;Magnus Callavik;
Appeared in: Proceedings of the IEEE
Publication date: Nov 2017, volume: 105, issue:11, pages: 2082 - 2098
Publisher: IEEE
 
» Hybrid Attitude and Gyro-Bias Observer Design on $SO(3)$
Abstract:
This paper presents an approach for the design of globally exponentially stable hybrid attitude and gyro-bias observers on . First, we propose a hybrid observer developed in a generic manner involving a generic family of potential functions with specific properties. Thereafter, we present a design method for such potential functions via an appropriate angular warping transformation applied to a new potential function on . This results in a hybrid observer that uses directly body-frame measurements of known inertial vectors.
Autors: Soulaimane Berkane;Abdelkader Abdessameud;Abdelhamid Tayebi;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 6044 - 6050
Publisher: IEEE
 
» Hybrid Vehicle Energy Management: Singular Optimal Control
Abstract:
Hybrid vehicle energy management is often studied in simulation as an optimal control problem. Under strict convexity assumptions, a solution can be developed using Pontryagin's minimum principle. In practice, however, many engineers do not formally check these assumptions resulting in the possible occurrence of so-called unexplained “numerical issues.” This paper intends to explain and solve these issues. Due to the binary controlled-state variable considered (e.g., switching on/off an internal combustion engine) and the use of a lookup table with linear interpolation (e.g., engine fuel consumption map), the corresponding Hamiltonian function can have multiple minima. Optimal control is not unique. Moreover, it is defined as being singular. Consequently, an infinite number of optimal state trajectories can be obtained. In this paper, a control law is proposed to easily construct a few of them.
Autors: Sébastien Delprat;Theo Hofman;Sébastien Paganelli;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9654 - 9666
Publisher: IEEE
 
» Hypergraph-Based Binary Locally Repairable Codes With Availability
Abstract:
We study a hypergraph-based code construction for binary locally repairable codes (LRCs) with availability. A symbol of a code is said to have -availability if it can be recovered from disjoint repair sets of other symbols, each set of size at most . We refer a systematic code to an LRC with -availability if its information symbols have -availability and a code to an LRC with -availability if its all symbols have -availability. We construct binary LRCs with -availability from linear -uniform -regular hypergraphs. As a special case, we also construct binary LRCs with -availability from labeled linear -uniform -regular hypergraphs. Moreover, we extend the hypergraph-based codes to increase the minimum distance. All the proposed codes achieve a well-known Singleton-like bound with equality.
Autors: Jung-Hyun Kim;Hong-Yeop Song;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2332 - 2335
Publisher: IEEE
 
» Hyperspectral Band Selection Using Improved Classification Map
Abstract:
Although it is a powerful feature selection algorithm, the wrapper method is rarely used for hyperspectral band selection. Its accuracy is restricted by the number of labeled training samples and collecting such label information for hyperspectral image is time consuming and expensive. Benefited from the local smoothness of hyperspectral images, a simple yet effective semisupervised wrapper method is proposed, where the edge preserved filtering is exploited to improve the pixel-wised classification map and this in turn can be used to assess the quality of band set. The property of the proposed method lies in using the information of abundant unlabeled samples and valued labeled samples simultaneously. The effectiveness of the proposed method is illustrated with five real hyperspectral data sets. Compared with other wrapper methods, the proposed method shows consistently better performance.
Autors: Xianghai Cao;Cuicui Wei;Jungong Han;Licheng Jiao;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2147 - 2151
Publisher: IEEE
 
» Hyperspectral Image Classification via Low-Rank and Sparse Representation With Spectral Consistency Constraint
Abstract:
In this letter, a low-rank and sparse representation classifier with a spectral consistency constraint (LRSRC-SCC) is proposed. Different from the SRC that represents samples individually, LRSRC-SCC reconstructs samples jointly and is able to capture the local and global structures simultaneously. In this proposed classifier, an adaptive spectral constraint is imposed on both the low-rank and sparse terms so as to better reveal the data structure and enhance its discriminative power. In addition, the alternating direction method is introduced to solve the underlying minimization problem, in which, more importantly, the subobjective function associated with the low-rank term is optimized based on the rank equivalence between a matrix and its Gram matrix, resulting in a closed-form solution. Finally, LRSRC-SCC is extended to LRSRC-SCCE for fully exploiting the spatial information. Experimental results on two hyperspectral data sets demonstrate that the proposed LRSRC-SCC and LRSRC-SCCE methods outperform some state-of-the-art methods.
Autors: Lei Pan;Heng-Chao Li;Hua Meng;Wei Li;Qian Du;William J. Emery;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2117 - 2121
Publisher: IEEE
 
» Hyperspectral Imagery Denoising by Deep Learning With Trainable Nonlinearity Function
Abstract:
Hyperspectral images (HSIs) can describe subtle differences in the spectral signatures of objects, and thus they are effective in a wide array of applications. However, an HSI is inevitably contaminated with some unwanted components like noise resulting in spectral distortion, which significantly decreases the performance of postprocessing. In this letter, a deep stage convolutional neural network (CNN) with trainable nonlinearity functions is applied for the first time to remove noise in HSIs. Besides the fact that the weight and bias matrices are learned from cubic training clean-noisy HSI patches, the nonlinearity functions in each stage are also trainable, which differ from the conventional CNN with a fixed nonlinearity function. Compared with the state-of-the-art HSI denoising methods, the experimental results on both synthetic and real HSIs confirm that the proposed method can obtain a more effective and efficient performance.
Autors: Weiying Xie;Yunsong Li;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1963 - 1967
Publisher: IEEE
 
» Hyperspectral Pansharpening With Guided Filter
Abstract:
A new hyperspectral (HS) pansharpening method based on guided filter is proposed in this letter. The proposed method, which obtains the spatial detail difference of each band successively, is different from the traditional component substitution method. The detail information of each band is extracted at first. Then, the panchromatic (PAN) image is sharpened to enhance the details. The spatial information difference between the enhanced PAN image and the detail information of each band is obtained using the guided filter, without causing spectral and spatial distortion. In order to reduce spectral distortion and add enough spatial information, the injection gains matrix is generated. The fused HS image is finally achieved by injecting the corresponding spatial difference into each band of the interpolated HS image. Experiments demonstrate that the proposed method can obtain superior performance in terms of subjective and objective evaluations.
Autors: Jiahui Qu;Yunsong Li;Wenqian Dong;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2152 - 2156
Publisher: IEEE
 
» Hyperthermic Effects of FeCoNi-Coated Glass Fibers in Alternating Magnetic Field
Abstract:
FeCoNi-coated glass fibers were synthesized using the electroless plating method, and the hyperthermic effects of FeCoNi-coated glass fibers in alternating magnetic fields were evaluated. The thickness of the coated FeCoNi was approximately on glass fibers with a diameter of approximately 15–. The saturation magnetization was approximately 150 emu/g. The heat elevations of FeCoNi-coated glass fibers were measured with the increasing number of fibers (4, 8, 12, 16, and 20 pieces of fibers) in silicon oil under an alternating magnetic field (AMF) at different intensities and frequencies. The elevated equilibrium temperatures linearly increased from 34.3 °C to 55.9 °C with an increasing number of FeCoNi-coated glass fibers from 4 to 20 pieces under an AMF of 105 Oe and 250 kHz. The specific loss power (SLP) was approximately 30 W/g. The heat behavior was examined as a function of the AMF and frequency. The AMF intensity was changed 60, 75, 90, and 105 Oe at 250 kHz, and the AMF frequency was changed 169, 213, 250, and 291 kHz at 105 Oe. The elevated equilibrium temperatures of 20 pieces of fibers increased from 46.8 °C to 56 °C and 46.7 °C to 61 °C with the increasing AMF intensity and frequency, respectively. The SLP also increased from 12.8 to 36.5 W/g.
Autors: Jinu Kim;Byung Mun Jung;Sang Bok Lee;Ki Hyeon Kim;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» IAA-Based High-Resolution ISAR Imaging With Small Rotational Angle
Abstract:
The Fourier transform-based range Doppler method is commonly used in an inverse synthetic aperture radar. Although it has achieved good success in most scenarios, its performance is determined by the rotational angle, and the cross-range resolution is extremely low in the case of a small rotational angle. In this letter, to improve the cross-range resolution, a novel cross-range compression scheme based on the iterative adaptive approach (IAA) is proposed. In addition to the standard IAA to achieve high resolution, the efficient IAA is introduced to suppress the sidelobes due to noise. Both the simulation and experimental results demonstrate that the proposed method has the advantages of parameter-free, high accuracy, and high efficiency.
Autors: Pengjiang Hu;Shiyou Xu;Wenzhen Wu;Biao Tian;Zengping Chen;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1978 - 1982
Publisher: IEEE
 
» ICA Based Semi-Blind Decoding Method for a Multicell Multiuser Massive MIMO Uplink System in Rician/Rayleigh Fading Channels
Abstract:
A massive multiple-input multiple-output (MIMO) system, which utilizes a large number of antennas at base stations to communicate with multiple user terminals each with a single antenna, is one of the most promising techniques for future wireless communications systems. A successful massive MIMO implementation relies on accurate channel estimation, which is typically performed through pilot sequences. However, the channel estimation performance or massive MIMO performance is limited by pilot contamination due to unavoidable reuse of pilot sequences from terminals in neighboring cells. In this paper, a semi-blind decoding method based on independent component analysis (ICA), channel energy levels, and reference bits is proposed. Specifically, the proposed decoding method uses ICA to separate and decode the received signals and to estimate the channels. The estimated channel energy is used to differentiate the in-cell signals and the neighboring cell signals, and reference bits are applied to identify a desired signal among signals within a cell. The analytical performance results of the proposed decoding method are derived. Numerical results show that the proposed semi-blind decoding method has better bit error rate performance and higher transmit efficiency than the traditional minimum mean-square error decoding method and the singular value decomposition-based decoding method.
Autors: Lei Shen;Yu-Dong Yao;Haiquan Wang;Huaxia Wang;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7501 - 7511
Publisher: IEEE
 
» ICSE Highlights
Abstract:
This issue’s column reports on papers from the 2017 International Conference on Software Engineering. Topics include context-based analytics, defect prediction, software development and energy consumption, continuous delivery, and continuous deployment.
Autors: Jeffrey C. Carver;Alexander Serebrenik;
Appeared in: IEEE Software
Publication date: Nov 2017, volume: 34, issue:6, pages: 18 - 20
Publisher: IEEE
 
» Identification of Dominant Low Frequency Oscillation Modes Based on Blind Source Separation
Abstract:
On-line monitoring and analysis of low frequency oscillation (LFO) are important for stability and security of a power system. This paper proposes a blind source separation (BSS) based method for LFO modal analysis of one-channel measured signal, which consists of a second-order blind identification (SOBI) algorithm and the Hilbert transform (HT) technique. This is the first time when a BSS technique is applied as a modal decomposition tool in this field. The proposed SOBI-HT based dominant mode identification method combines an iteration procedure with an identification procedure to determine the model order, and then identify dominant modes. The performance of the proposed method is evaluated on numerical simulation signals and a record of real data, verifying its effectiveness and accuracy.
Autors: A. Q. Zhang;L. L. Zhang;M. S. Li;Q. H. Wu;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4774 - 4782
Publisher: IEEE
 
» Identification of Modeling Boundaries for SSR Studies in Series Compensated Power Networks
Abstract:
Given large-scale power networks with series compensation, the study of subsynchronous resonance (SSR) is a significant challenge, in practice, due to the model complexity and computation burden. To tackle these difficulties, this paper proposes a method to reduce a large-scale system to an equivalent model using a metric called damping sensitivity index. The proposed metric can quantitatively identify the boundaries of the equivalent model that ensure the accurate studies of SSR and reduce the computation burdens greatly. The effectiveness of the method is verified by its application to the SSR investigation of the modified IEEE New England 10-machine 39-bus system and 16-machine 68-bus system. The equivalent models obtained by the proposed method are compared with the original systems in terms of driving point impedances, electrical damping, and transient torques. These results obtained show that the equivalent models from the proposed method can reproduce the SSR dynamics of the original systems with a much shorter computation time.
Autors: Wuhui Chen;Danhui Wang;Xiaorong Xie;Jin Ma;Tianshu Bi;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4851 - 4860
Publisher: IEEE
 
» IEEE Microwave Magazine Columnist Receives 2017 Apex Award [Awards]
Abstract:
Presents the recipient of the IEEE Microwave Magazine Columnist Receives 2017 Apex Award.
Autors: Alfy Riddle;
Appeared in: IEEE Microwave Magazine
Publication date: Nov 2017, volume: 18, issue:7, pages: 103 - 103
Publisher: IEEE
 
» IEEEXtreme?Engaging Student Branches [The Way Ahead]
Abstract:
Autors: J. Patrick Donohoe;
Appeared in: IEEE Potentials
Publication date: Nov 2017, volume: 36, issue:6, pages: 4 - 4
Publisher: IEEE
 
» Impact of Dynamic Interactions Introduced by the DFIGs on Power System Electromechanical Oscillation Modes
Abstract:
This paper derives the index of dynamic interactions (IDI), which is the sensitivity of a power system electromechanical oscillation mode (EOM) of concern to the dynamic interactions introduced by a grid-connected double-fed induction generator (DFIG). Based on the IDI, analysis is carried out with the following generally-applicable conclusions obtained: 1) Impact of dynamic interactions introduced by the DFIG increases when wind power penetration increases; 2) as long as the frequency response of an equivalent single DFIG model approximately matches the frequency response of a wind farm around the frequency of electromechanical oscillations of concern, this equivalent dynamic model of single DFIG can be used to represent the wind farm to examine the impact of wind farm on EOMs. Furthermore, an indicator of DFIG control (IDC) is derived for comparing the impact of terminal voltage control and reactive power control implemented by the DFIG. Main merit of the IDC is the computational simplicity without need to know dynamic model of the DFIG to indicate that either the terminal voltage control or the reactive power control is more beneficial to power system stability. An example multi-machine power system with grid-connected DFIGs is presented to demonstrate and validate the analysis and conclusions made in the paper.
Autors: Wenjuan Du;Xiao Chen;Hai Feng Wang;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4954 - 4967
Publisher: IEEE
 
» Impact of Trench Dimensions on the Device Performance of GaN Vertical Trench MOSFETs
Abstract:
In this letter, we have examined the impact of trench dimensions on the breakdown voltage and ON-resistance of trench MOSFETs fabricated on sapphire and bulk GaN substrates. Contrary to simulation studies, the breakdown voltage decreased with an increase in trench dimensions in devices fabricated on sapphire substrates. However, such breakdown voltage dependence with trench dimensions was not observed in devices fabricated on bulk GaN substrates of the same area. The observed trend on GaN on sapphire devices was associated with the equivalently reduced number of dislocations per device area. These results give an insight into how dislocations could affect breakdown voltage in power MOSFETs.
Autors: Chirag Gupta;Dong Ji;Silvia H. Chan;Anchal Agarwal;William Leach;Stacia Keller;Srabanti Chowdhury;Umesh K. Mishra;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1559 - 1562
Publisher: IEEE
 
» Impact of Tungsten Sputtering Condition on Magnetic and Transport Properties of Double-MgO Magnetic Tunneling Junction With CoFeB/W/CoFeB Free Layer
Abstract:
We investigated an effect of sputtering gas species (Ar, Kr, and Xe) for deposition of a W insertion layer in the CoFeB/W/CoFeB free layer on magnetic properties of the free layer and tunnel magnetoresistance (TMR) ratio of magnetic tunnel junctions (MTJs) stacks using the free layer annealed at 400 °C for 1 h. As the W insertion layer thickness increased, we found the degradation of perpendicular anisotropy and larger reduction of saturation magnetic moment per unit area in the free layer using Ar compared to those using Kr and Xe. We also found a smaller TMR ratio for the MTJ stack using Ar compared to those using Kr and Xe. Energy-dispersive X-ray spectrometry line analysis revealed more significant interdiffusion between W and CoFeB layers in the free layer using Ar than those using Kr and Xe, that could result in the smaller and perpendicular anisotropy in the free layer and smaller TMR ratio for the MTJ stack using Ar than those using Kr and Xe. We also investigated concentration of Ar, Kr, and Xe in W layers deposited using Ar, Kr, and Xe, respectively, by high-resolution Rutherford backscattering spectrometry, revealing that 0.2 at% Ar was detected in the W layer using Ar, while Kr and Xe were not detected in W layers using Kr and Xe. Such a difference in concentration of inert gas atoms in the W layer could be one possible reason for the difference about degree of interdiffusion between W and CoFeB layers.
Autors: H. Honjo;S. Ikeda;H. Sato;K. Nishioka;T. Watanabe;S. Miura;T. Nasuno;Y. Noguchi;M. Yasuhira;T. Tanigawa;H. Koike;H. Inoue;M. Muraguchi;M. Niwa;H. Ohno;T. Endoh;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Impacts of Retransmission Limit on Stability and Throughput Regions of S-ALOHA Systems
Abstract:
Limiting the number of retransmissions in practical random access systems such as S-ALOHA and IEEE 802.11 systems has been used, since it was often considered as a way of preventing the system from being congested, by dropping packets in retransmission or letting users know network congestion after the maximum of retransmissions. Therefore, it can be expected that the smaller the maximum of retransmissions is allowed, the smaller the backlog size gets with a higher packet dropping probability. This paper explores how such a retransmission limit alters the shape of the stability and throughput regions of S-ALOHA systems. To do this, we first consider an S-ALOHA system, where two users with infinite queue length have different packet arrival rate and retransmission probability, which is called asymmetric user. Then, we obtain those results of the systems with symmetric users.
Autors: Jun-Bae Seo;Hu Jin;Victor C. M. Leung;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10296 - 10306
Publisher: IEEE
 
» Implementation of Radiating Aperture Field Distribution Using Tensorial Metasurfaces
Abstract:
This paper deals with the design of tensorial modulated metasurfaces able to implement a general radiating aperture field distribution. A new aperture synthesis approach is introduced, based on local holography and variable impedance modulation. In particular, it is shown that tensorial metasurfaces can be used to generate general radiating distribution (phase and amplitude). In addition, a step-by-step algorithm is presented. In order to validate the method, several solutions are presented at 20 GHz which implement aperture distributions able to radiate different beams with general polarization.
Autors: M. Teniou;H. Roussel;N. Capet;G.-P. Piau;M. Casaletti;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 5895 - 5907
Publisher: IEEE
 
» Implementation of the Single Hysteron Model in a Finite-Element Scheme
Abstract:
The single hysteron model is identified to reconstruct the magnetization processes of a grain-oriented electrical steel and it is implemented in a finite-element scheme. The model involves the Zeeman energy and the anisotropy energy of the material and an interaction field to take into account others terms, such as the magnetoelastic energy, the exchange energy, inclusions, and crystallographic discontinuities. The interaction field is evaluated experimentally using a round rotational single sheet tester, where a disk sample of the material is excited for several rotational magnetization processes. Details about the finite-element scheme, the computational time, and the memory allocations involved in the simulations are presented and discussed.
Autors: E. Cardelli;A. Faba;A. Laudani;G. M. Lozito;S. Quondam Antonio;F. Riganti Fulginei;A. Salvini;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Improper Signaling Versus Time-Sharing in the SISO Z-Interference Channel
Abstract:
It has recently been shown that improper signaling enlarges the rate region of the Gaussian single-antenna one-sided interference channel (Z-interference channel, ZIFC) under the assumptions that all input signals are Gaussian and that interference is treated as noise. It was pointed out that this result also holds if time-sharing between different operation points is allowed. However, the existing literature has considered the problem only for time-sharing under short-term average power constraints, i.e., if the average transmit powers are limited individually in each time slot. We consider the same problem under long-term average power constraints, where the transmit powers are limited only after averaging over all time slots. Interestingly, this modification changes the outcome of the study significantly: we can show that improper signaling can no longer bring any gains in this case.
Autors: Christoph Hellings;Wolfgang Utschick;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2432 - 2435
Publisher: IEEE
 
» Improved 3-D Magnetic Properties Measurement of Silicon Steel Laminations Based on a Novel Sensing Structure
Abstract:
The precise 3-D magnetic property measurement of the silicon steel is important to improve the efficiency and performance in electrical equipment, such as electrical machines and power transformers. An improved 3-D magnetic property measurement method of the silicon steel laminations is proposed by using a novel sensing structure with interconnecting multiple sensing coils covered on the surface of the cubic specimen. Based on the new coil structure with high precise coefficients from comprehensive calibration, the accurate relationship between B and H vectors is obtained and analyzed under alternating and 3-D rotating excitations with the feedback control method, especially when the laminated direction is considered. Consequently, the experimental data of magnetic properties with high precision can be obtained, which can provide important reference in designing and optimizing electrical equipment.
Autors: Yongjian Li;Xin Geng;Changgeng Zhang;Rongge Yan;Jianguo Zhu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Improved Broadband Matching Bound
Abstract:
In radio frequency systems where a load is driven by a source through a passive impedance matching circuit, the bandwidth over which match can be attained is limited. The Bode–Fano upper bound is often invoked to find this limit. We show that the bound is loose for some loads and, hence, cannot be attained by any network. We present a simple method to improve the bound and give conditions under which the improved bound is tight. The improved bound requires no additional assumptions or conditions beyond what is used for the Bode–Fano bound. Applications to analytical and numerical load models are demonstrated.
Autors: Ding Nie;Bertrand M. Hochwald;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 5878 - 5885
Publisher: IEEE
 
» Improved Depth-Assisted Error Concealment Algorithm for 3D Video Transmission
Abstract:
In this paper, a whole frame loss error concealment algorithm for three-dimensional video coding is proposed. The main concept of the proposed algorithm is to extrapolate the motion vectors for concealing a current error block by jointly considering the available motion vector and the depth information. In addition, the depth information is adopted to help the derivation of reference pixels for concealing errors in the case that suitable motion vectors cannot be obtained by the motion vector extrapolation process alone. Simulation results demonstrate that our proposed algorithm can achieve up to 0.52 dB PSNR, as well as subjective quality improvement, compared to previous work.
Autors: Pin-Cheng Huang;Jie-Ru Lin;Gwo-Long Li;Kuang-Han Tai;Mei-Juan Chen;
Appeared in: IEEE Transactions on Multimedia
Publication date: Nov 2017, volume: 19, issue:11, pages: 2625 - 2632
Publisher: IEEE
 
» Improved Efficiency of Tapered Magnetic Flux Concentrators With Double-Layer Architecture
Abstract:
Being able to increase the sensitivity of magnetoresistive sensors, by orders of magnitude, provides a route toward challenging detection levels, and opens the way for new applications. This paper describes a novel architecture of magnetic flux concentrators to achieve an improved guiding efficiency, combining materials with different magnetic properties, and a vertical tapering. The novelty consists in the concentration of the magnetic flux kept by the entire structure in a reduced cross-sectional area within the vicinity of the spinvalve sensor. Depending on the configuration of the double-layer magnetic flux concentrators, average sensitivity gains of and were obtained. This enhanced guiding efficiency also reduced the impact of a misalignment between the device sensing direction and the applied magnetic field, since the device performance is not compromised until a misalignment angle °. This further stabilization may arise from the vertical tapering of the magnetic flux concentrator, being consistent with 2-D finite-element simulations.
Autors: J. Valadeiro;D. C. Leitao;S. Cardoso;P. P. Freitas;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Improved Figure-of-Eight Coil for Transcranial Magnetic Stimulation Using Magnetic Resonant Coupling
Abstract:
This paper proposes an improved figure-of-eight coil for transcranial magnetic stimulation (TMS) by using the magnetic resonant coupling (MRC) effect, aiming to improve the treatment effect for psychiatric disorders. The proposed MRC-based figure-of-eight coil consists of two reverse-winding resonance coils, which embraces two series-connected source coils, respectively. Different from conventional figure-of-eight coils, the proposed topology can produce the resonant electromagnetic field to accumulate the stimulation energy. In such ways, the improved TMS system can effectively enhance the stimulation focality and depth while significantly reducing the requirement of the power supply, thus improving the safety as well as facilitating the miniaturization and portability. Last, this paper gives the simulated and experimental results to verify the theoretical analysis, which can further illustrate the feasibility of the proposed MRC-based figure-of-eight coil for TMS systems.
Autors: Zhen Zhang;Wenjie Ai;Bin Deng;Wei Han;Jiang Wang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Improved High-Frequency Rotating Magnetic Properties Tester for Nanocrystalline Soft Magnetic Material
Abstract:
In order to study and analyze the rotating magnetic properties for nanocrystalline material, an improved 2-D high-frequency magnetic properties tester with step-shaped excitation windings and composite sensing structure is designed and modeled. Magnetic concentration and core poles optimization are performed in 2-D tester construction, which can generate relatively uniform and strong magnetic field in the testing area. By using the composite sensing structure of sensing coil combined with needle probe method, and signals can accurately be detected. Meanwhile, feedback control algorithm and harmonic compensation are established to obtain the desired magnetization curves and improve the measurement precision.
Autors: Yongjian Li;Qing Zhao;Lixiang Wang;Changgeng Zhang;Rongge Yan;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Improved ISAC Algorithm to Retrieve Atmospheric Parameters From HyTES Hyperspectral Images Using Gaussian Mixture Model and Error Ellipse
Abstract:
In-scene atmospheric correction (ISAC) is a procedure that accounts for atmospheric effects by direct use of the hyperspectral radiance data without recourse to ancillary meteorological data. This letter aims to improve the accuracy of the ISAC algorithm. In the ISAC method after calculating brightness temperature, the computed radiance and measured radiance at the sensor are plotted on a graph in each band. Then, to estimate atmospheric parameters, the straight line is fit to the upper boundary of the plot. One of the issues in ISAC is to find an optimal upper boundary of data. The main innovation of this letter is the use of Gaussian mixture model (GMM) and error ellipse to find the optimal upper boundary of data and fit the line to it. In the line fitting process, first, a GMM with the optimum class number derived by Akaike information criterion (AIC) is implemented on thermal hyperspectral data and then, the optimal upper boundary is selected for each class and a straight line is fit to it. Finally, the desired parameters are obtained with weighted linear combination of the results from all classes. For quality assessment, the results were compared with atmospheric products of Hyperspectral Thermal Emission Spectrometer sensor and atmospheric parameters that were obtained from traditional ISAC. Root-mean-square errors for atmospheric transmittance obtained from GMM for bands 9.8 and are 0.0008 and 0.0106 and those for upwelling atmospheric radiance are 0.675 and 0.0265, respectively.
Autors: Faeze Soleimani vosta kolaei;Mehdi Akhoondzadeh;Hamid Ghanbari;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2087 - 2091
Publisher: IEEE
 
» Improved Message Passing Algorithms for Sparse Code Multiple Access
Abstract:
Sparse code multiple access (SCMA) is one of the nonorthogonal multiple access techniques for the 5G system. SCMA can provide different levels of overloading to meet the diverse traffic connectivity requirements. However, its relatively high computational complexity of multiuser detection is still a significant concern for practical implementation, even when the sparse structure has already been employed. In this paper, a design framework for an improved SCMA multiuser detector is proposed based on the message passing algorithm (MPA). As the primary SCMA detector, two aspects of MPA are simplified and optimized. First, we introduce a lookup table (LUT) scheme to reduce the computational complexity of the operation in the MPA. In contrast to the extensive Jacobian approximation, the proposed LUT method can guarantee the stable convergence of the MPA for SCMA. Second, a series of novel scheduling schemes are proposed to speed up the convergence. A single scheduling MPA (SS-MPA) method is given to enhance the convergence performance of MPA, where the soft messages in the function nodes and variable nodes are serially calculated and synchronously updated. To further improve the throughput of the MPA, a multiple scheduling MPA (MS-MPA) is proposed. In this method, multiple detectors are used to calculate in parallel and update the node messages by different orders. Since the scheduling strategies of message update are optimized, both the SS-MPA and MS-MPA can converge more quickly than the conventional MPA. Theoretical analyses and simulation results regarding the error performance and convergence properties of the above schemes are included.
Autors: Jincheng Dai;Kai Niu;Chao Dong;Jiaru Lin;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9986 - 9999
Publisher: IEEE
 
» Improved Optoelectronic Performance of High-Voltage Ultraviolet Light-Emitting Diodes Through Electrode Designs
Abstract:
High-efficiency high-voltage ultraviolet light-emitting diodes (HV-UVLEDs) consisting of a microcells array with an area of were designed and fabricated via the electrode pattern and interconnect technique. Polymer material was used to fill trench with planarization, and interconnection technology was used for metal layer connection to address wiring defect issue. In comparison with the conventional lateral UV-LED (C-UVLED), which had 33.6% and 34.7% enhancement in the light output power and wall-plug efficiency (at 1.5 W) of the HV-UVLEDs. A 56% improvement in the external quantum efficiency droop behavior was achieved for the HV-UVLEDs when compared with that of C-UVLED. This improvement can be attributed to superior current spreading in the HV-UVLED due to its smaller microcells, which increases light-emission efficiency overall.
Autors: Ching-Ho Tien;Chen-Hao Kuo;Dong-Sing Wuu;Ray-Hua Horng;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4526 - 4531
Publisher: IEEE
 
» Improved Range Analysis in Fixed-Point Polynomial Data-Path
Abstract:
In range analysis (RA), suitable integer bit-widths are assigned to the variables so that no overflow occurs. Although the accuracy in RA rather than error analysis has more impact on hardware cost and efficiency, there are few works that offer new approaches to improve RA. Arithmetic functions, mostly represented by polynomials, are normally suitable for both optimization and verification purposes. In this paper, a safe and more accurate RA of feed-forward fixed-point polynomial data-flow graphs is proposed. The method employs particular features of RA and maps it to a specific class of polynomial optimization problems. The proposed method provides tighter ranges while taking less runtime in comparison with satisfiability-modulo theory-based method. Furthermore, the improved ranges lead to enhance the area and delay efficiency more than 50% and 24%, respectively, when the circuits are implementing the functions in comparison with the state-of-the-art techniques.
Autors: Mahdieh Grailoo;Bijan Alizadeh;Behjat Forouzandeh;
Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Publication date: Nov 2017, volume: 36, issue:11, pages: 1925 - 1929
Publisher: IEEE
 
» Improved Successive-Cancellation Decoding of Polar Codes Based on Recursive Syndrome Decomposition
Abstract:
In this letter an improved method for the successive-cancellation decoding of polar codes is proposed. To avoid computations associated with redundant tree-traversals and syndrome calculations, recursive properties of polar codes are newly exploited in the proposed algorithm. Instead of computing a syndrome vector at every node, some syndrome vectors are directly obtained by recursively decomposing the syndrome vector computed previously. Furthermore, a modified syndrome check rule is proposed to prune unnecessary sub-trees efficiently. Compared with the latest pruning method, the proposed method reduces the latency by 23% for a (2048, 1024) polar code without sacrificing the error-correcting performance.
Autors: Jaejoon Choi;In-Cheol Park;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2344 - 2347
Publisher: IEEE
 
» Improved Synchrophasor Models for Power System Dynamic Stability Evaluation Based on IEEE C37.118.1 Reference Architecture
Abstract:
Synchrophasors are an emerging power system wide-area dynamic performance monitoring and control technology. The IEEE standard C37.118.1 outlines specifications for the construction of synchrophasor units, in which two reference synchrophasor models are proposed for protection (P-type) and measurement (M-type) purposes. This paper develops improved synchrophasor models for power system dynamic stability/performance evaluation based on the reference architecture proposed in the IEEE standard C37.118.1, considering frequency error (FE) and the total vector error (TVE) as the main performance indices. The quadrature demodulation filters are designed explicitly considering the impact of harmonic distortion and out-of-band interference, and thus optimized quadrature demodulation filters improve estimation performance during adverse conditions. Furthermore, a special emphasis is placed on the input low-pass filter to attenuate high-frequency components above the Nyquist rate. The improved synchrophasor models are rigorously tested to ensure compliance with performance requirements stipulated in the IEEE standard. Results show that improved synchrophasor models significantly enhance the FE while ensuring compliance requirements for the TVE.
Autors: Chathura Thilakarathne;Lasantha Meegahapola;Nuwantha Fernando;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2937 - 2947
Publisher: IEEE
 
» Improvement in Offaxis Neuromuscular Control Under Slippery Conditions Following Six-Week Pivoting Leg Neuromuscular Training
Abstract:
Knee injuries are usually associated with offaxis loadings in the transverse and frontal planes. Thus, improvement of lower limb offaxis neuromuscular control is important in knee injury prevention and post-injury rehabilitation. The goal of this paper was to investigate the effects of six-week pivoting offaxis intensity adjustable neuromuscular control training (POINT) using a custom-made offaxis elliptical trainer on lower limb offaxis neuromuscular control performance in trained and untrained functional tasks under slippery conditions. Twenty-six subjects participated in 18 sessions of POINT (three sessions per week for six weeks) and 25 subjects served as controls who did a regular workout. Offaxis neuromuscular control performance measures in terms of pivoting instability, sliding instability, and time-to-peak offaxis EMG entropy were evaluated on both groups under slippery conditions including a trained free pivoting task and untrained free sliding task and free pivoting and sliding task. Compared with the control group, the training group significantly decreased pivoting instability and the time-to-peak offaxis EMG entropy in lower limb muscles, indicating improvement in offaxis neuromuscular control performance. Furthermore, the training group showed reduced pivoting instability and sliding instability during the untrained free pivoting and sliding task. This paper may help us develop more focused and effective offaxis training programs to reduce knee injuries associated with offaxis loadings.
Autors: Song Joo Lee;Yupeng Ren;Joel M. Press;Jungwha Lee;Li-Qun Zhang;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Nov 2017, volume: 25, issue:11, pages: 2084 - 2093
Publisher: IEEE
 
» Improvement of a Pansharpening Method Taking Into Account Haze
Abstract:
Pansharpening is an important technique used to generate high-quality high-spatial-resolution multispectral (MS) bands by fusing low-spatial-resolution MS bands and a panchromatic (PAN) band obtained by the same sensor. A PAN-modulation (PM)-based pansharpening method taking account of haze, which is referred as Haze- and Ratio- based (HR) method, has been demonstrated to yield good performances, indicating that the impact of haze should be considered in PM-based methods. It is obvious that the haze values used in the HR fusion influence the spectral vectors of fused pixels, thus affect the spectral distortion of fused images. In order to reach stable and good performances of the HR method, the determination of the optimal haze values is discussed in this study. First, six approaches for haze values determination, which are variations of the histogram minimal approach and the darkest pixel approach employed by the image-based dark-object subtraction method for atmospheric correction of remote-sensed images, are compared. Then, an improved approach for haze values determination is proposed. The proposed approach is proved to be effective for improving the performance of the HR method. This is very important for the employment of the HR method in practical applications and by more researchers.
Autors: Hui Li;Linhai Jing;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 5039 - 5055
Publisher: IEEE
 
» Improvement of Handheld Radar Operators’ Hazard Detection Performance Using 3-D Visualization
Abstract:
Handheld ground-penetrating radar systems are employed in both military and humanitarian demining operations. Radar system operators are given the difficult job of determining the nature of subsurface objects from signal reflections in real time. Current systems require operators to multitask both collection and classification. This letter tested a 3-D data visualization method against a 2-D method. The 3-D method attempts to separate tasks by not forcing operators to classify objects in real time. Data showed that users classifying objects with the 3-D system had better performance and also reported that this system was more user-friendly. In addition, users were able to classify underground objects quicker with the 3-D system. The results of this letter demonstrate the benefit of 3-D visualization in ground scanning systems in increasing performance and decreasing cognitive load.
Autors: Drew B. Gonsalves;Lawrence H. Winner;Joseph N. Wilson;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1888 - 1892
Publisher: IEEE
 
» Improvement of Preventing Particle Generation by Using Collision Assisted Sintering Process (CASP)
Abstract:
To suppress particle generation in a dry etching apparatus, the deposition method of Y2O3 film used as chamber wall coating was studied. The conventional Y2O3 coating is deposited by atmospheric plasma spraying. Compared to the conventional method, collision assisted sintering process (CASP) provided denser film with less defects, higher density, and less particle detachment, even after plasma exposure. By using CASP coating in the chamber, we were able to reduce particles by 67%.
Autors: Tetsuyuki Matsumoto;Rikyu Ikariyama;Makoto Saito;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 362 - 366
Publisher: IEEE
 
» Improving BER Performance by Using V-Shaped Read Head Array in Heat-Assisted Magnetic Recording
Abstract:
Heat-assisted magnetic recording (HAMR) is the leading candidate for the next generation of magnetic recording. In HAMR, the thermal profile (with circular contours produced by the near-field transducer) combined with the current writer structures results in recording transitions with noticeable curvature, which causes edge erasure at high linear density and increased transition noise. This transition curvature affects the bit error rate (BER) and is thus important to the model. As the micromagnetic simulations are computationally demanding, in this paper we investigate a fast and simplified write model to capture the transition curvature of HAMR. As the transition curvature causes signal degradation in normally oriented read head array (NHA) having straight gaps, we propose a V-shaped read head array (VHA) by rotating the side readers at appropriate angles to follow the curvature shapes and improve the readback signal. Simulations indicate that, with 2-D signal processing, VHA can provide improved BER performance compared to the NHA in the presence of readback transition curvature on HAMR media. Also this paper indicates that the Curie temperature variance affects BER performance more severely than the anisotropy field variance.
Autors: Yao Wang;B. V. K. Vijaya Kumar;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 7
Publisher: IEEE
 
» Improving MOCVD MoS2 Electrical Performance: Impact of Minimized Water and Air Exposure Conditions
Abstract:
The effects of oxidants both in the channel and contact regions of MoS2 transistors are discussed through a systematic experimental study. This letter highlights the issues of partial instability in metal-organic chemical vapor deposition MoS2 and proposes a procedure, which considerably improves the electrical characteristics of back-gated transistors. By avoiding ambient exposure and layer oxidation, contact resistance can be reduced and intrinsic mobility increased by 50%.
Autors: Alessandra Leonhardt;Daniele Chiappe;Inge Asselberghs;Cedric Huyghebaert;Iuliana Radu;Stefan De Gendt;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1606 - 1609
Publisher: IEEE
 
» Improving QoS and QoE Through Seamless Handoff in Software-Defined IEEE 802.11 Mesh Networks
Abstract:
To deliver an enhanced mobility experience, wireless networks must provide seamless handoff to mobile clients. Moreover, the handoff process should preserve quality-of-service (QoS) and quality of experience (QoE) at acceptable levels. This letter presents a strategy to provide seamless mobility in wireless mesh networks, considering software-defined network-controlled handoff and passive measurements. To validate the proposal, we deployed a 802.11/OpenFlow test bed and performed extensive experiments. Experimental results demonstrated improvements of QoE up to 70% while keeping key QoS metrics below real-time applications constraints.
Autors: Italo Valcy S. Brito;Gustavo B. Figueiredo;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2484 - 2487
Publisher: IEEE
 
» Improving Throughput and Fairness of Convergecast in Vehicular Networks
Abstract:
Delivering data from source vehicles to infrastructures, or convergecast, is a fundamental operation in vehicular networks. However, the network capacity of vehicular network is always limited because of scarce inter-vehicle contacts. Thus, throughput maximization of convergecast in vehicular networks is of great importance. The unique characteristics of vehicular networks, however, present great challenges including frequent connection unavailability and opportunistic contacts. We propose an approach called ConvergeCode for improving the convergecast throughput in vehicular networks, which employs random linear coding for packet delivery. A vehicle randomly combines all received coded data and forwards it to any contacted vehicles. Through extensive empirical study based on the two large datasets of real GPS traces, we make the key observation that significant throughput gain can be achieved by using network coding but a serious fairness issue arises. In this paper, we study the problem of maximizing the throughput of convergecast in vehicular networks at the same time enhancing the fairness among different source nodes. We first formulate the problem of allocating inter-vehicle contacts as a lexicographical max-min multi-source flow problem, and then develop an efficient approximation algorithm with -approximation guarantee. Simulations based on real vehicular GPS traces have been performed and results show that the throughput is improved by 74-110 percent while the lexicographical max-min fairness is achieved.
Autors: Ruobing Jiang;Yanmin Zhu;Yudong Yang;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Nov 2017, volume: 16, issue:11, pages: 3070 - 3083
Publisher: IEEE
 
» In Memoriam
Abstract:
It is with great sadness that we inform you that Sergey Kharkovsky, one of the journal's Associate Editors, passed away on September 6, 2017.
Autors: Sergey Kharkovsky;Shervin Shirmohammadi;Alessandro Ferrero;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2802 - 2802
Publisher: IEEE
 
» In Situ Mechanical Characterization of Multilayer Soft Tissue Using Ultrasound Imaging
Abstract:
In this paper, we report the development of a technique to characterize layer-specific nonlinear material properties of soft tissue in situ with the potential for in vivo testing. A soft tissue elastography robotic arm system comprising of a robotically manipulated 30 MHz high-resolution ultrasound probe, a custom designed compression head, and load cells has been developed to perform compression ultrasound imaging on the target tissue and measure reaction forces. A multilayer finite element model is iteratively optimized to identify the material coefficients of each layer. Validation has been performed using tissue mimicking agar-based phantoms with a low relative error of ∼7% for two-layer phantoms and ∼10% error for three layer phantoms when compared to known ground-truth values obtained using a commercial material testing system. The technique has then been used to successfully determine the in situ layer-specific mechanical properties of intact porcine stomach. The mean C10 and C20 for a second-order reduced polynomial material model were determined for the muscularis (6.41 ± 0.60, 4.29 ± 1.87 kPa), submucosal (5.21 ± 0.57, 3.68 ± 3.01 kPa), and mucosal layers (0.06 ± 0.02, 0.09 ± 0.24 kPa). Such a system can be utilized to perform in vivo mechanical characterization, which is left as future work.
Autors: Saurabh Dargar;Ali C. Akyildiz;Suvranu De;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Nov 2017, volume: 64, issue:11, pages: 2595 - 2606
Publisher: IEEE
 
» In the Pursuit of Hygge Software
Abstract:
Hygge is Danish and Norwegian for well-being related to conviviality. Health and social relations are tightly bound, so how can we integrate today’s technologies to provide hygge? Two healthcare scenarios show ways to achieve hygge by integrating software and distributed technologies, using elements of the U’Ductor model. This model ubiquitously supports noncommunicable-disease care, providing a way for applications to communicate, automatically receive health status updates, and search for nearby resources and people. The ChronicDuctor and ChronicPrediction apps use U’Ductor to improve patient care.
Autors: Henrique Damasceno Vianna;Jorge Luis Victória Barbosa;Fábio Pittoli;
Appeared in: IEEE Software
Publication date: Nov 2017, volume: 34, issue:6, pages: 48 - 52
Publisher: IEEE
 
» In-DRAM Data Initialization
Abstract:
Initializing memory with zero data is essential for safe memory management. However, initializing a large memory area slows down the system significantly. The most likely cause for initialization to slow down the system is the limited DRAM initialization method. At present, the only way to initialize DRAM area is to execute multiple WRITE commands. However, the WRITE command slows the initialization because of its small granularity and data bus occupancy. In this brief, we propose an efficient in-DRAM initialization method inspired by the internal structure and operation of DRAM. The proposed method, called row reset, uses a DRAM row buffer to zero out a single DRAM row at a time. Row Reset allows for parallel initialization on multiple DRAM banks without using off-chip data transfer, thus reducing initialization time by up to 63 times. Row reset is a practical approach, because it can be implemented with existing circuitry in DRAM without additional area overhead.
Autors: Hoseok Seol;Wongyu Shin;Jaemin Jang;Jungwhan Choi;Jinwoong Suh;Lee-Sup Kim;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Nov 2017, volume: 25, issue:11, pages: 3251 - 3254
Publisher: IEEE
 
» In-Memory Processing Paradigm for Bitwise Logic Operations in STT–MRAM
Abstract:
In the current big data era, the memory wall issue between the processor and the memory becomes one of the most critical bottlenecks for conventional Von-Newman computer architecture. In-memory processing (IMP) or near-memory processing (NMP) paradigms have been proposed to address this problem by adding a small amount of processing units inside/near the memory. Unfortunately, although intensively studied, prior IMP/NMP platforms are practically unsuccessful because of the fabrication complexity and cost efficiency by integrating the processing units and memory on the same chip. Recently, emerging nonvolatile memories provide new possibility for efficiently implementing the IMP/NMP paradigm. In this paper, we propose a cost-efficient IMP/NMP solution in spin-transfer torque magnetic random access memory (STT–MRAM) without adding any processing units on the memory chip. The key idea behind the proposed IMP/NMP solution is to exploit the peripheral circuitry already existing inside memory (or with minimal changes) to perform bitwise logic operations. Such an IMP/NMP platform enables rather fast logic operations as the logic results can be obtained immediately through just a memory-like readout operation. Memory read and logics not, and/nand, and or/nor operations can be achieved and dynamically configured within the same STT–MRAM chip. Functionality and performance are evaluated with hybrid simulations under the 40 nm technology node.
Autors: Wang Kang;Haotian Wang;Zhaohao Wang;Youguang Zhang;Weisheng Zhao;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» In-Plane Magnetic Anisotropy Detection of Crystal Grain Orientation in Goss-Textured Ferromagnets
Abstract:
In this paper, a preliminary study about non-destructive diagnostics of crystal grain orientation in laminated Goss-textured magnetic material is presented. The reconstruction of the local lattice orientation is achieved by exploiting the surface magnetic anisotropy that is obtained by the contact-less magnetic measurements and lag angle plots elaboration. In addition, the experimental measurements are compared to the magnetic simulations of the crystal grains in order to extrapolate the local orientation of the system. The evaluation of the tilt angle between the easy axis and the rolling direction, as well as the angle of the other axes respect to the lamination plane, is carried out for different grains of an Fe–Si grain-oriented alloy specimen.
Autors: D. Candeloro;E. Cardelli;A. Faba;M. Pompei;S. Quondam Antonio;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» In-Store Pickup and Returns for a Dual Channel Retailer
Abstract:
The Internet and technology have changed how products are sold and delivered to consumers. Today, the most significant growth in online retailing comes from multichannel retailers that sell products both in stores and over the Internet. Recently, these retail/e-tail organizations have attempted to leverage their “brick” locations by allowing customers to pick up or return orders purchased online at retail store locations. Such options let online customers avoid both long carrier lead times and high shipping costs. However, these options come at a cost to the retailer. This paper develops a mathematical model for analytically examining the cost and value of providing in-store pickup and return options in multi-echelon retail/e-tail organizations. In this light, the model determines the optimal subset of a retailer/e-tailer's stores that should be set up to handle in-store pickups and online returns under stochastic channel demands. Computational results show that optimizing the set of pickup and return locations can reduce system cost by up to 20% on average over arbitrarily enabling all stores with Internet pickup/return capabilities, and firms can substantially increase customer value while maintaining cost minimization as an important selection criterion in choosing pickup and return locations.
Autors: Stephen Mahar;P. Daniel Wright;
Appeared in: IEEE Transactions on Engineering Management
Publication date: Nov 2017, volume: 64, issue:4, pages: 491 - 504
Publisher: IEEE
 
» In0.53Ga0.47As/InP Trench-Gate Power MOSFET Based on Impact Ionization for Improved Performance: Design and Analysis
Abstract:
A novel In0.53Ga0.47As/InP heterostructure trench-gate power MOSFET employing impact ionization at the hetero junction of n In0.53Ga0.47As drift region and n+InP drain region has been proposed. The impact ionization supports the band-to-band tunneling at heterojunction, which further increases the drain current. It results in reduced ON-state resistance and improved transconductance without compromising with the breakdown voltage as compared with the conventional silicon trench-gate MOSFET (CTGMOS). Using 2-D numerical simulations, we demonstrate that the proposed device exhibits ~440% improvement in peak transconductance, ~92% reduction in on-state resistance, ~ 10% increase in breakdown voltage, ~16% increase in switching speed, and ~93% improvement in figure of Merit (. as compared with CTGMOS.
Autors: Navneet Kaur Saini;Shubham Sahay;Raghvendra Sahai Saxena;Mamidala Jagadesh Kumar;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4561 - 4567
Publisher: IEEE
 
» InAs/InGaAsSb/GaSb Nanowire Tunnel Field-Effect Transistors
Abstract:
Tunnel field-effect transistors with ability to operate well below the thermal limit (with a demonstrated 43 mV/decade at VDS = 0.1 V) are characterized in this paper. Based on 88 devices, the impact of the low subthreshold swing on the overall performance is studied. Furthermore, correlation between parameters that are important for device characterization is determined.
Autors: Elvedin Memisevic;Johannes Svensson;Erik Lind;Lars-Erik Wernersson;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4746 - 4751
Publisher: IEEE
 
» Incentive Mechanisms for Data Dissemination in Autonomous Mobile Social Networks
Abstract:
This work focuses on the incorporation of incentive stimulations into data dissemination in autonomous mobile social networks with selfish nodes. The key challenge of enabling incentives is to effectively track the value of a message under such a unique network setting with intermittent connectivity and multiple interest data types. We propose two data dissemination models: the data pulling model where mobile users pull data from data providers, and the data pushing model where data providers generate personalized data and push them to the intended users. For data pulling, we present effective mechanisms to estimate the expected credit reward of a message that helps intermediate nodes to evaluate the potential reward of it. Nodal message communication is formulated as a two-person cooperative game, whose solution is found by a heuristic approach which achieves Pareto optimality. Under the data pushing model, “virtual checks” are introduced to eliminate the needs of accurate knowledge about whom and how many credits data providers should pay. The check buying process is formulated as an online auction model to further accelerate the circulation of credits. Extensive simulations carried out based on real-world traces show the proposed schemes achieve better performance than fully cooperative scheme, but significantly reduce communication cost.
Autors: Ting Ning;Yang Liu;Zhipeng Yang;Hongyi Wu;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Nov 2017, volume: 16, issue:11, pages: 3084 - 3099
Publisher: IEEE
 
» Incentivized Outsourced Computation Resistant to Malicious Contractors
Abstract:
With the rise of Internet computing, outsourcing difficult computational tasks became an important need. Yet, once the computation is outsourced, the job owner loses control, and hence it is crucial to provide guarantees against malicious actions of the contractors involved. One may want to ensure that both the job itself and any inputs to it are hidden from the contractors, while still enabling them to perform the necessary computation. Furthermore, one would check that the computation was carried out correctly. In this paper, we are not concerned with hiding the job or the data, but our main task is to ensure that the job is computed correctly. We also observe that not all contractors are malicious; rather, majority are rational. Thus, our approach brings together elements from cryptography, as well as game theory and mechanism design. We achieve the following results: (1) We incentivize all the rational contractors to perform the outsourced job correctly, (2) we guarantee high fraction (e.g., 99.9 percent) of correct results even in the existence of a relatively large fraction (e.g., 33 percent) of malicious irrational contractors in the system, (3) and we show that our system achieves these while being almost as efficient as running the job locally (e.g., with only 3 percent overhead). Such a high correctness guarantee was not known to be achieved with such efficiency.
Autors: Alptekin Küpçü;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Nov 2017, volume: 14, issue:6, pages: 633 - 649
Publisher: IEEE
 
» Incidence Angle Dependence of First-Year Sea Ice Backscattering Coefficient in Sentinel-1 SAR Imagery Over the Kara Sea
Abstract:
We have studied the incidence angle () dependence of the sea ice backscattering coefficient (°) for Sentinel-1 (S-1) extra wide (EW) mode dual-polarization (HH/HV) synthetic aperture radar (SAR) imagery acquired over the Kara Sea under winter and summer melting conditions. The determination of the ° versus dependence was based on SAR image pairs acquired on ascending and descending orbits over the same sea ice area with a short time difference. The SAR noise floor was subtracted from the HV images. From the image pairs 1.1 by 1.1 km windows representing level first-year ice (LFYI) and deformed first-year ice (DFYI) were manually selected, and a linear regression was fit between the resulting ° and differences of the windows to estimate the slope (dB/1°) between ° and . For example, under winter condition for DFYI at HH- and HV-polarizations was found to be −0.24 and −0.16 dB/1°, respectively, and for LFYI at HH-pol- rization was −0.25 dB/1°. It was not possible to determine a reliable for LFYI at HV due to a contamination effect of the S-1 noise floor. The values at HH compared well with previous studies. They can be used to compensate the ° incidence angle variation in the S-1 EW SAR images with good accuracy. The HH values are applicable to other S-1 imaging modes and other C-band SAR sensors like RADARSAT-2. Unfortunately, the HV values are specific to the S-1 EW mode due to the noise floor problem.
Autors: Marko Mäkynen;Juha Karvonen;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6170 - 6181
Publisher: IEEE
 
» Incorporating Open Source Data for Bayesian Classification of Urban Land Use From VHR Stereo Images
Abstract:
This study investigates the incorporation of open source data into a Bayesian classification of urban land use from very high resolution (VHR) stereo satellite images. The adopted classification framework starts from urban land cover classification, proceeds to building-type characterization, and results in urban land use. For urban land cover classification, a preliminary classification distinguishes trees, grass, and shadow objects using a random forest at a fine segmentation level. Fuzzy decision trees derived from hierarchical Bayesian models separate buildings from other man-made objects at a coarse segmentation level, where an open street map provides prior building information. A Bayesian network classifier combining commonly used land use indicators and spatial arrangement is used for the urban land use classification. The experiments were conducted on GeoEye stereo images over Oklahoma City, USA. Experimental results showed that the urban land use classification using VHR stereo images performed better than that using a monoscopic VHR image, and the integration of open source data improved the final urban land use classification. Our results also show a way of transferring the adopted urban land use classification framework, developed for a specific urban area in China, to other urban areas. The study concludes that incorporating open source data by Bayesian analysis improves urban land use classification. Moreover, a pretrained convolutional neural network fine tuned on the UC Merced land use dataset offers a useful tool to extract additional information for urban land use classification.
Autors: Mengmeng Li;Kirsten M. de Beurs;Alfred Stein;Wietske Bijker;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 4930 - 4943
Publisher: IEEE
 
» Incorporating Squirrel-Cage Induction Machine Models in Convex Relaxations of OPF Problems
Abstract:
The optimal power flow (OPF) problem determines a minimum cost operating point for an electric power system. Recently developed convex relaxations are capable of globally solving certain OPF problems. Using a semidefinite relaxation of the OPF problem as an illustrative example, this letter presents a method for extending convex relaxations of the OPF problem to include steady-state squirrel-cage induction machine models.
Autors: Daniel K. Molzahn;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4972 - 4974
Publisher: IEEE
 
» Increased Red Frequency Shift in Coherent Mid-Infrared Supercontinuum Generation From Tellurite Microstructured Fibers
Abstract:
We investigate coherent broadband mid-infrared supercontinuum generation in all normal dispersion (ANDi) tellurite microstructured fibers through numerical simulations. The proposed tellurite microstructured fibers (PTMFs) have an inverted L-shaped ANDi profile in the wavelength range of < 5.2 μm. By using a 2-μm femtosecond laser as the pump source, the spectral broadening occurs in the PTMF, which is caused by self-phase modulation (SPM) and optical wave breaking. Interestingly, SPM induced spectral broadening is larger on the Stokes side than the antistokes side, since the trailing edge of laser pulse becomes smoother than its leading edge, and the effect of self-steepening (SS) on pulse shape is compensated by the effect of the dispersion in the PTMF. Such a phenomenon is inaccessible in previously reported optical fibers, since the trailing edge of output pulse is steeper than the leading edge of output pulse when SS occurs in previously reported ANDi fibers. As a result, coherent broadband mid-infrared supercontinuum light with long operating wavelength can be generated in the PTMF.
Autors: Qing Li;Lai Liu;Zhixu Jia;Guanshi Qin;Yasutake Ohishi;Weiping Qin;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4740 - 4746
Publisher: IEEE
 
» Independent Encoding Joint Sparse Representation and Multitask Learning for Hyperspectral Target Detection
Abstract:
Target detection is playing an important role in hyperspectral image (HSI) processing. Many traditional detection methods utilize the discriminative information within all the single-band images to distinguish the target and the background. The critical challenge with these methods is simultaneously reducing spectral redundancy and preserving the discriminative information. The multitask learning (MTL) technique has the potential to solve the aforementioned challenge, since it can further explore the inherent spectral similarity between the adjacent single-band images. This letter proposes an independent encoding joint sparse representation and an MTL method. This approach has the following capabilities: 1) explores the inherent spectral similarity to construct multiple sub-HSIs in order to reduce spectral redundancy for each sub-HSI; 2) takes full advantage of the prior class label information to construct reasonable joint sparse representation and MTL models for the target and the background; 3) explores the great difference between the target dictionary and background dictionary with different regularization strategies in order to better encode the task relatedness for two joint sparse representation and MTL models; and 4) makes the detection decision by comparing the reconstruction residuals under different prior class labels. Experiments on two HSIs illustrated the effectiveness of the proposed method.
Autors: Yuxiang Zhang;Wu Ke;Bo Du;Xiangyun Hu;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1933 - 1937
Publisher: IEEE
 
» Indoor Localization Without a Prior Map by Trajectory Learning From Crowdsourced Measurements
Abstract:
Accommodation of a situation when a prior map is not available in an indoor localization system is valuable to cost-effective operations by removing a need for map drawing and map updating. This paper suggests a trajectory learning method using crowdsourced measurements in order to support the absence of map. A localization framework based on a particle filter is formalized by machine-learning-based feature extraction and Gaussian process (GP) regression. The feature extraction algorithm reduces dimensionality of sparse measurement vector, and it is applied to detect floor level and designated landmarks. Also, the combination of the feature extraction and the GP regression is used for modeling nonlinear relationship between location and measurement. By this combination, locations of Wi-Fi access points are not required to be known. From the field experimental results, we confirm that the detections of floor level and landmarks are accurate, the learned trajectories are close to the true map, and positioning accuracy is improved thanks to the learning-aided localization.
Autors: Jaehyun Yoo;Karl Henrik Johansson;Hyoun Jin Kim;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2825 - 2835
Publisher: IEEE
 
» Influence of Ar Pressure on the Magnetic Properties of Amorphous FeGaSiB Thin Films
Abstract:
Magnetostrictive amorphous FeSiB and FeGaSiB thin films thickness 50 nm have been grown by the co-sputtering-evaporation technique with a range of Ar pressure (4–bar) to control the Ga percentage within the films and study their effect on the magnetic, structural, and magnetostriction properties. By X-ray diffraction, it was found that all the films had an amorphous structure and the only peaks were present for Si substrate. Using a magneto-optical Kerr effect magnetometer, it was found that, for the FeSiB films, the anisotropy field ) increased slowly as the pressure increased, while for the FeGaSiB films, the saturation field A/m for all pressures. For both the film sets, the coercive field was less than 800 A/m. The magnetostriction constants of the FeSiB thin films increased with increasing pressure. While for the FeGaSiB films, the magnetostriction constant decreased with increasing the sputtering gas pressure, with the maximum ppm, at the lowest pressure bar. Thus, it was determined that the addition of Ga atoms reduced the intrinsic stress within the films, while maintaining the amorphous morphology.
Autors: Qayes A. Abbas;Nicola A. Morley;August Johansson;Thomas Thomson;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Influence of Carbon Nanotubes Saturable Absorbers Diameter on Mode-Locking Erbium-Doped Fiber Laser Performance
Abstract:
We present a study about the influence of saturable absorbers single-wall carbon nanotubes (CNT) diameter on the passive mode-locking Erbium doped fiber laser performance. We used several samples of CNT with different mean diameters (from 0.8 to 1.4 nm) and distributions to fabricated CNT/polymer films. Films with 1.0 nm mean diameter CNT showed best results in terms of larger laser bandwidths and shorter pulse durations, compared to the other CNT samples used in our experiments. This result is due to the fact that 1.0 nm diameter CNT absorption energy gap (∼0.8 eV) is close to the photon energy of operating Erbium-doped fiber laser wavelength (∼1557 nm). Laser bandwidths up to 8.7 nm and pulse durations as short as 0.55 ps were obtained.
Autors: David Steinberg;Henrique G. Rosa;Eunezio A. Thoroh de Souza;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4804 - 4808
Publisher: IEEE
 
» Influence of Ce Content on the Mechanical Properties of Sintered (Ce, Nd)–Fe–B Magnets
Abstract:
The (R,Ce)–Fe–B magnets have been successfully industrialized in recent years. The mechanical property of sintered permanent magnets is one important aspect of their comprehensive performances, which directly influences the service reliability and the production cost. In this paper, the bending strength, fracture toughness, Vickers hardness, and brittleness index of commercial (R1–xCex)30.5–31.5Febal.B1M1 magnets with different cerium contents have been investigated. The micro-fractures of the magnets were observed by a scanning electron microscopy equipped with energy dispersive X-ray analysis system. It shows that the bending strength and the fracture toughness of (R,Ce)–Fe–B magnets have a downward tendency with increasing Ce content x, while the Vickers hardness of the magnets varies irregularly with Ce contents in this paper. The optimum mechanical properties have been obtained in the (R1–xCex)30.5–31.5Febal.B1M1 magnet with ; the bending strength, fracture toughness and brittleness index of the magnet with are obviously superior to those of the ordinary sintered Nd–Fe–B magnets. Some flocculent oxide phases have been discovered in the (R,Ce)–Fe–B magnet with . The flocculent phases may absorb the crack propagating energy, and reduce the stress concentration at a crack tip, which is b- neficial to strengthening and toughening of (R,Ce)–Fe–B magnets. However, the mechanical properties are obviously worse for the magnet with (Ce/RE = 45%). That is probably because the microstructures of the magnet with become deteriorated, in which abnormally large grains have been observed.
Autors: Anhua Li;Yueming Zhang;Wei Li;Haibo Feng;Yang Zhao;Minggang Zhu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Influence of End Effects on Direct- and Quadrature-Axis Inductances in Linear Electromagnetic Actuators
Abstract:
This paper presents an analysis of the direct- and quadrature-axis inductances for linear tubular actuators with permanent magnet arrays, highlighting and featuring how they are affected by the end effects. A semi-analytical and an experimental analysis are performed to prove the influence of end effects on self- and mutual inductances. The synchronous parameters, i.e., - and -axis inductances of the actuator, are determined using a semi-analytical method and an experimental method. Once the synchronous parameters are all identified, high performance control methods (such as direct force control and vector control) may be implemented.
Autors: Ben Hur B. Boff;Ana P. Zanatta;David G. Dorrell;Paulo R. Eckert;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 7
Publisher: IEEE
 
» Influence of External Current on Yokeless Electric Current Transducers
Abstract:
Yokeless electric current transducers have compact size, but they are sensitive to external magnetic fields, including those caused by electric currents in their vicinity. It is often believed that this unwanted sensitivity can be effectively suppressed by using a differential sensor. In this paper, we investigate the effect of external current with arbitrary position on busbar differential current sensor. We show the main disadvantage of the differential current sensor: increased sensitivity to currents in the transversal direction, which are not sensed by a single sensor. We analyze by finite element method simulation also the influence of real conductor size and uneven density of ac currents. The results were verified on 1000 A current transducer using a pair of microfluxgate sensors. The realistic suppression of close currents depends on the conductor angular position and in 10 cm distance it can be as low as 50, but it can be corrected if the geometry is known.
Autors: Pavel Ripka;Andrey Chirtsov;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Influence of Inductance Properties on a Magnetic Levitation for Thin-Steel Plates
Abstract:
There are many studies on magnetic levitation, some of which were already realized in railways. The authors in our laboratory now try to apply the magnetic levitation techniques to the steel processing industry. Therefore, we aim at the construction of magnetic levitation system for very thin steel plates. However, it is extremely difficult to levitate them perfectly, because of its vibratory properties and awkward electromagnetic properties. We have already studied the elasticity of the thin steel plate mechanically and shown its control methodology. In this research, we carry out many measurements about “the magnetic saturation and the magnetic leakage” and formulate its influence. Last, with a controller designed by considering the influence, we accomplish a stable levitation for a very thin steel plate.
Autors: Yusuke Takada;Toshiki Kimura;Toshiko Nakagawa;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 

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