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

» Nuclear Norm-Based 2DLPP for Image Classification
Abstract:
Two-dimensional locality preserving projections (2DLPP) that use 2D image representation in preserving projection learning can preserve the intrinsic manifold structure and local information of data. However, 2DLPP is based on the Euclidean distance, which is sensitive to noise and outliers in data. In this paper, we propose a novel locality preserving projection method called nuclear norm-based two-dimensional locality preserving projections (NN-2DLPP). First, NN-2DLPP recovers the noisy data matrix through low-rank learning. Second, noise in data is removed and the learned clean data points are projected on a new subspace. Without the disturbance of noise, data points belonging to the same class are kept as close to each other as possible in the new projective subspace. Experimental results on six public image databases with face recognition, object classification, and handwritten digit recognition tasks demonstrated the effectiveness of the proposed method.
Autors: Yuwu Lu;Chun Yuan;Zhihui Lai;Xuelong Li;Wai Keung Wong;David Zhang;
Appeared in: IEEE Transactions on Multimedia
Publication date: Nov 2017, volume: 19, issue:11, pages: 2391 - 2403
Publisher: IEEE
 
» Numerical Analysis and Optimization of Miniature Electrohydrodynamic Air Blowers
Abstract:
As the demand for advanced microelectronic devices of small form factor and high power density has increased, the capability of the miniaturized mechanical solutions for effective cooling has become critical. Electrohydrodynamic (EHD) air blowers have great potential as alternative cooling solutions over the traditional mechanical systems to meet the thermal management requirements with flexible design and considerable flow production for effective heat removal. In this paper, a numerical analysis and optimization of wire-to-plane EHD air blowers are performed based on 2-D developed models validated against previous data. For a range of blower heights from 2 to 10 mm, the location and length of the collecting plane located at the blower walls apart from the emitter wire electrode are investigated and optimized based on pumping efficiency using the ranges of fixed operating powers and voltages. Simple relations for each optimization method are presented to determine the optimal blower configuration. Results of flow rate and static pressure obtained by each optimized blower show good agreement with those predicted by EHD scaling laws previously presented.
Autors: Abdulmajeed A. Ramadhan;Nikil Kapur;Jonathan L. Summers;Harvey M. Thompson;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 3007 - 3018
Publisher: IEEE
 
» Numerical Investigation of the Surface Wave Formation in a Microwave Plasma Torch
Abstract:
The microwave plasma torch (MPT) is an attractive plasma source in both industry and scientific research because of its advantages in electrodeless operation ability, high energy efficiency, and flexibility under different operational conditions. However, relatively few numerical studies have been carried out for the MPT fed by a rectangular waveguide in two or even three dimensions. Therefore, this paper presents a 2-D, axisymmetric, and stationary fluid models to characterize the MPT, with an emphasis on the mechanism of the surface wave formation and the sustentation of the plasma column. Nine partial differential equations are included in this research, coupling microwave radiation, heat transfer, plasma bulk flow, and transport of different species with each other. The obtained results reveal how the traveling surface wave occurs and elucidate the consequent influence of the surface wave formation. Furthermore, this paper demonstrates the extension of the plasma column length and the propagation of the surface wave with an increase in the total plasma-absorbed microwave power. The dependence of the plasma column length on the plasma-absorbed microwave power is found to be motivated by the surface wave propagation. The limitations of the model and the difficulties in its numerical implementation are also discussed in the paper.
Autors: Wencong Zhang;Junwu Tao;Kama Huang;Li Wu;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 2929 - 2939
Publisher: IEEE
 
» Numerical Simulation of Plasma Near the Cathode Spot of Vacuum Arc
Abstract:
Kinetic numerical simulation of plasma near the cathode spot (CS) was performed. Two types of possible solutions for the self-sustained CS on copper cathode were found. The firs type of solutions is valid for quasi-stationary spot with radius of about . Stationary solution in this case is possible with cathode temperature 4.2–4.5 kK, current density A/cm2, and applied voltage 20–25 V. The second type of solution is obtained for the spot with radius of and spherical geometry of plasma expansion. Possible solutions were obtained for the cathode temperature of above 6.2 kK, current density of about A/cm2 and applied voltage of 15–25 V. Transient simulations of the near-cathode plasma expansion have shown that if current density remains less than A/cm2 then the plasma expansion has a “quiet” self-similar character. At higher current density the plasma expansion has an essentially nonstationary character. The high-density current leads first to the development of Buneman instability and second to the plasma rupture with the creation of conditions for collective acceleration of ions toward the cathode and toward the anode. The accelerated ions create an additional powerful heat flux to the cathode, which should facilitate the reproduction of the CSs in the spark stage of vacuum discharge.
Autors: Dmitry L. Shmelev;Sergey A. Barengolts;Mikhail M. Tsventoukh;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 3046 - 3053
Publisher: IEEE
 
» Numerical Study on a Novel Curie Temperature Controlled Hybrid Thermo-Magnetic Structure for Magnetic Random Access Memories
Abstract:
High thermal stability, a fast switching time, and a low switching current are key characteristics of merit for realizing gigabit-class magnetic random access memory (MRAM). Especially, the switching current needs to be reduced significantly for creating high-density MRAM. In order to realize these necessary features, a number of magnetic tunnel junction (MTJ) structures have been proposed. A previous study of ours led to the proposal of a novel Curie-temperature-controlled hybrid thermo-magnetic structure for MRAM, for the purpose of improving these advantageous properties. This paper presents an analysis of the switching time and switching current by using micromagnetic simulation techniques for comparing our structures with various MTJ structures that have been proposed recently. We confirm that our novel structure can improve the switching characteristics of MRAM. The results of our analysis revealed that a 44% lower switching current and a 32% faster switching time can be achieved compared with the conventional structure.
Autors: Ken Machida;Yoshiaki Sonobe;Yoshinobu Nakatani;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» O-MAC: Opportunistic MAC Protocol for M2M Communication in WiFi White Spaces
Abstract:
Machine-to-machine (M2M) communication comprises of autonomous devices communicating with each other without human intervention. The explosive growth in devices using an M2M communication and the shortage of spectrum has made network access for such devices a challenging problem. While M2M communication in the unlicensed bands is attractive from an economic perspective, such bands are also under use by existing technologies, such as WiFi. In this letter, we propose a new opportunistic medium access control protocol to allow an M2M communication within white spaces (i.e., periods without traffic) of WiFi networks. The proposed protocol increases the effective utilization of the channel without any significant impact on existing WiFi networks.
Autors: Ajinkya Rajandekar;Biplab Sikdar;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2440 - 2443
Publisher: IEEE
 
» Object Detection Using Convolutional Neural Networks in a Coarse-to-Fine Manner
Abstract:
Object detection in remote sensing images has long been studied, but it remains challenging due to the diversity of objects and the complexity of backgrounds. In this letter, we propose an object detection method using convolutional neural networks (CNNs) in a coarse-to-fine manner. In the coarse step, coarse candidate regions that may contain objects are proposed. In the fine step, fine candidate regions are cropped from coarse candidate regions, and are classified as objects or backgrounds. We design a concise and efficient framework that can propose fewer candidate regions and extract more discriminative features. The framework consists of two eight-layer CNNs that are well designed and powerful. To use CNNs to detect inshore ships, image samples are required, each of which should contain only one ship. However, the traditional image cropping method cannot generate such samples. To solve this problem, we present an orientation-free image cropping method that can generate trapezium rather than rectangle samples, making inshore ship detection by CNN feasible. Experimental results on Google Earth images demonstrate that the proposed method outperforms existing state-of-the-art methods.
Autors: Xiaobin Li;Shengjin Wang;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2037 - 2041
Publisher: IEEE
 
» Object Tracking Using Multiple Features and Adaptive Model Updating
Abstract:
Correlation filter-based tracking methods have been intensively investigated for their high efficiency and robustness. However, a single feature-based tracker cannot adapt to challenging situations, such as severe deformation, rotation, and illumination variations. Besides, a simple linear interpolation-based model updating mechanism is prone to model degradation, and consequently tracker drifting. In this paper, a 2-D location filter is combined with a 1-D scale filter to jointly estimate the state of object under tracking, and three complementary features are integrated to further enhance the overall tracking performance. Besides, we define a penalty factor for adaptive model updating, to achieve a balance between stability and flexibility, especially when the object is under occlusion. Extensive experiments have been conducted on four large-scale data sets, namely, the object tracking benchmark, VOT15, Temple-Color128, and the UAV123 tracking benchmark. Quantitative and qualitative results show that our proposed tracker achieves promising results in terms of tracking accuracy, robustness, and speed as compared with other popular trackers, and is highly suitable for real-time applications, such as unmanned aerial vehicles. It outperforms the state-of-the-art methods under different nuisances, including scale variation, deformation, occlusion, rotation, and out-of-view.
Autors: Qingyong Hu;Yulan Guo;Zaiping Lin;Wei An;Hongwei Cheng;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2882 - 2897
Publisher: IEEE
 
» Object-Level Motion Detection From Moving Cameras
Abstract:
It is important for a moving observer to be able to identify his/her surrounding objects and determine whether these objects are moving or stationary, which is called object-level motion detection. Detecting object-level motion from moving cameras is a difficult problem to solve for collision-free navigation due to the dual motion introduced by the mixture of the camera motion and the object motion. This paper presents a novel technique that detects object-level motion from a freely moving camera using only two consecutive video frames. A context-aware motion descriptor (CMD) is designed based on the object’s moving speed and moving direction relative to that of the moving camera. The CMD employs the contextual information, e.g., the optical flow of the image background surrounding the moving object of interest, which describes the object motion behavior better than other contexts such as the camera’s GPS and direction. The inconsistency between the histogram of oriented optical flow of the object and its surrounding background is measured for the object-level motion detection. The proposed technique has been evaluated over two types of widely studied objects, i.e., vehicles and humans that are captured with different sizes, moving speeds, and image backgrounds using a moving camera. Experiments on challenging real-world videos show promising performance in object-level motion detection.
Autors: Tao Chen;Shijian Lu;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Nov 2017, volume: 27, issue:11, pages: 2333 - 2343
Publisher: IEEE
 
» Observability of Multi-Agent Systems With Switching Topology
Abstract:
This brief studies the observability of multi-agent systems with switching topology. First, we consider the first-order multi-agent systems. Then, we prove that the multi-agent system with switching topology is observable if each subgraph is weakly connected. It is shown that the multi-agent system with switching topology can be observable even if each of its subsystems is not observable. Second, we establish graphical conditions for the observability of multi-agent systems with general linear dynamics. Finally, an example is given to demonstrate the effectiveness of the theoretical result.
Autors: Zehuan Lu;Lin Zhang;Long Wang;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Nov 2017, volume: 64, issue:11, pages: 1317 - 1321
Publisher: IEEE
 
» Observation of Magnetoresistance Effect in $n$ -Type Non-Degenerate Germanium With Co2Fe0.4Mn0.6Si Heusler Alloy Electrodes
Abstract:
The local 3-terminal magnetoresistance properties of n-Ge/MgO/Co2Fe0.4Mn0.6Si lateral spin-valve devices were systematically investigated. In the spin extraction condition, clear steep voltage changes were successfully observed. We measured the bias voltage and temperature dependences of the spin resistance-area product. At a high bias voltage, the spin signal increased with increasing voltage, reaching a maximum value of at mV. The signal decreased with increasing temperature but was still observed up to 160 K.
Autors: Takeo Koike;Mikihiko Oogane;Tetsurou Takada;Hidekazu Saito;Yasuo Ando;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Observation of Mode Competition in Operation of a 420 GHz, TE17.4 Second Harmonic Gyrotron With Complex Cavity
Abstract:
The lack of terahertz sources, especially the high-power ones, is one of the main obstacles in the developments of terahertz science and technology. A gyrotron, based on the electron cyclotron masers, is one of the most promising sources to generate high-power terahertz radiation. Therefore, a 0.42-THz gyrotron with a gradually tapered complex cavity operating at the second harmonic is designed and experimentally tested in this paper. Experimental results show that the designed gyrotron can generate high-power THz radiation of 19.2 kW at 0.42 THz with the beam voltage of 51 kV, beam current of 4.4 A and the external magnetic field of 8.03 T, corresponding to an efficiency of 8.6%. By comparison with theoretical results, it can be shown that the operating mode in the designed gyrotron is confirmed as the TE17.4 mode. At the same time, the excitation of the fundamental TE0.5 mode is also observed in the experiment when the beam current is increased to 7.3 A, where the operating frequency is 216.143 GHz. Through extensive experimental efforts, it is found that the designed gyrotron can operate stably at the desired TE17.4 mode when the beam current is in the range of 3–7 A.
Autors: Qixiang Zhao;Sheng Yu;Tianzhong Zhang;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4700 - 4705
Publisher: IEEE
 
» Observer-Based Control for Piecewise-Affine Systems With Both Input and Output Quantization
Abstract:
This technical note is concerned with the problem of simultaneous design of observers and controllers for a class of piecewise-affine systems against signal quantization occurring in both measurement output and control input channels. The general scenario is considered that system state and estimated state may not be in the same operating region. By a novel quantization-error-dependent Lyapunov function, the stability and performance criteria are first established for the augmented system composed of a closed-loop control system and an estimation error system with the aid of -procedure involving the region partition information of the original system. Then, by the cone complementary linearization algorithm, the desired observer and controller gains are solved simultaneously such that the resulting closed-loop system is asymptotically stable with a prescribed performance index. Finally, a networked single-link robot arm is utilized to demonstrate the effectiveness of the proposed control strategy.
Autors: Lixian Zhang;Zepeng Ning;Wei Xing Zheng;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5858 - 5865
Publisher: IEEE
 
» Observer-Based Control of 2-D Markov Jump Systems
Abstract:
This brief is concerned with the problem of asynchronous observer-based control for 2-D Markov jump systems (MJSs). Based on a linear matrix inequality setting, some equivalent criteria are proposed to ensure that the closed-loop hidden MJS is stochastically stable. On the basis of the derived stability conditions, the design problem of asynchronous observer-based controllers is addressed. The effectiveness of the design scheme is verified by a practical example in thermal process models.
Autors: Le Van Hien;Hieu Trinh;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Nov 2017, volume: 64, issue:11, pages: 1322 - 1326
Publisher: IEEE
 
» Obtaining Microscopic Images Under a High 20-T Pulse Magnetic Field Using an Optimized Coil
Abstract:
We optimized the coil of a pulsed electromagnet to be able to obtain dynamically microscopic images of crystals in a pulsed magnetic field of a maximum intensity of 20 T and pulsewidth of 3 ms. The pulsed field induces an eddy current that influences the nearby apparatus and objective lens made up of a conducting non-magnetic material. Developing a much shorter length of coil was required, because the working distance of the objective lens was incapable of preventing eddy currents. We calculated the maximum field and pulsed width; as a result, a coil wound with wire of 1-mm diameter in ten layers gives an ideal shape of the magnetic field when using a 10-mF capacitor bank with charge voltage of 700 V. Wound to the prescribed coil parameter values, the coil performed as expected. We demonstrate its performance with microscopic images taken using the optimized coil of the dynamic orientational behavior of diamagnetic monosodium urate crystals suspended in aqueous solution. The lying down of the acicular crystals through magnetic orientation just after application of the pulse field was observed dynamically.
Autors: Atom Hamasaki;Yuka Takeuchi;Sumio Ozeki;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Ocean and Geothermal Energy Systems
Abstract:
This paper presents techno–economic summaries of ocean wave, tidal and current, ocean thermal, and geothermal energy, including grid interface characteristics. These forms of energy represent a significant opportunity to complement diversified energy conversion portfolios. Ocean wave energy conversion relies on the capture of kinetic and potential energy in moving and elevated water in an ocean wave. Tidal and current technology converts the kinetic energy in moving water, much like a wind turbine. Ocean thermal converts the energy available in the temperature gradient of warm surface water and cold deep water. Last, geothermal conversion utilizes the hot rock and water deep within the Earth. The total global average wave resource is estimated at approximately 2000 GW, with approximately 300 GW in the United States. The total global tidal resource is estimated at approximately 1000 GW, with 50 GW in the United States. The marine current resource estimate for the Florida Current in the southeast United States is estimated at 5 GW. Ocean thermal has a global capacity estimate of 5000 GW. Last, the global conventional hydrothermal geothermal capacity estimate is approximately 200 GW, but with much more possible through enhanced geothermal systems. For cost, it was found that the long-term projected wave energy conversion cost is $0.10–0.15/kWh. The long-term projected tidal cost is found to be $0.025–0.25/kWh. Ocean thermal long-term cost is projected at $0.10–0.18/kWh. And last, geothermal, being more closely aligned with traditional thermal generation, is estimated at $0.03/kWh to $0.15/kWh.
Autors: Annette von Jouanne;Ted K. A. Brekken;
Appeared in: Proceedings of the IEEE
Publication date: Nov 2017, volume: 105, issue:11, pages: 2147 - 2165
Publisher: IEEE
 
» Ocean Surface Current Inversion Method for a Doppler Scatterometer
Abstract:
The ocean surface current is a very important parameter of ocean dynamic environment. It is connected to global climate change, marine environment forecasting, marine navigation, engineering security, and so on. The observation and prediction of ocean surface current have attracted more and more concern. Doppler Scatterometer (DopScat) is a new type of radar for ocean surface wind and current field remote sensing. The ocean surface current inversion method of DopScat impacts the measurement accuracy directly. In this paper, we establish the simulation model of a DopScat and provide the radial velocity error model. The numerical ocean surface Doppler spectrum model is also introduced and validated with the empirical geophysical model function in C-band (CDOP). The suitable ocean wave elevation spectrum and directional distribution function are selected. What is more, this paper establishes the maximum likelihood estimation (MLE) method to retrieve the ocean surface current and wind simultaneously. The retrieval accuracy for different positions in cross track, different wind speeds, and different current speeds are analyzed. At last, the global ocean current field is observed by DopScat and the ocean current is retrieved. In our simulation, the orbit parameters and observation geometry of DopScat are the same as that of HY-2A scatterometer. The retrieval results show that global current speed standard deviation can be smaller than 0.18 m/s for five days and grid average.
Autors: Qingliu Bao;Mingsen Lin;Youguang Zhang;Xiaolong Dong;Shuyan Lang;Peng Gong;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6505 - 6516
Publisher: IEEE
 
» OFDM Without CP in Massive MIMO
Abstract:
We study the possibility of removing the cyclic prefix (CP) overhead from orthogonal frequency division multiplexing (OFDM) in massive multiple-input multiple-output (MIMO) systems. We consider the uplink transmission, while our results are applicable to the downlink as well. The absence of CP increases the spectral efficiency in expense of intersymbol interference and intercarrier interference. It is known that in massive MIMO, the effects of uncorrelated noise and multiuser interference vanish as the number of base station antennas tends to infinity. To investigate if the channel distortions in the absence of CP fade away, we study the performance of the standard maximum ratio combining receiver. Our analysis reveals that in this receiver, there always remains some residual interference leading to saturation of signal-to-interference-plus-noise ratio. To resolve this problem, we propose using the time reversal (TR) technique. Moreover, in order to further reduce the multiuser interference, we propose a zero-forcing equalization to be deployed after the TR combining. We compare the achievable rate of the proposed system with that of the conventional CP-OFDM. We show that in realistic channels, a higher spectral efficiency is achieved by removing the CP from OFDM, while reducing the computational complexity.
Autors: Amir Aminjavaheri;Arman Farhang;Ahmad Rezazadehreyhani;Linda E. Doyle;Behrouz Farhang-Boroujeny;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7619 - 7633
Publisher: IEEE
 
» Off-Body Antenna Wireless Performance Evaluation in a Residential Environment
Abstract:
Modern body-centric communication systems require good link quality. Antenna performance is of primary importance when meeting this requirement. This paper contributes a method suited to the difficult task of quantifying antenna performance in a body-centric communications system. In a case study, a planar wrist wearable antenna, which provides radiation pattern switching across the 2.4 GHz operating band through an innovative technique that does not require an additional switching mechanism, is benchmarked against a monopole and a patch antenna in a residential setting. The performance of the antenna and subsequently the benefits of the pattern-switching technique are successfully quantified. The holistic method includes both antenna measurements and channel simulation with ray tracing. Results are verified against real-world measurements.
Autors: Sema Dumanli;Lawrence Sayer;Evangelos Mellios;Xenofon Fafoutis;Geoffrey S. Hilton;Ian J. Craddock;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6076 - 6084
Publisher: IEEE
 
» Off-grid electricity projects are starved for funds [News]
Abstract:
Despite innovative off-grid technology and high-profile initiatives, electrification in sub-Saharan Africa still trails population growth. In 2009 there were 585 million people in the region without power. Five years later, that figure had risen to 632 million, according to the latest International Energy Agency statistics.
Autors: Peter Fairley;
Appeared in: IEEE Spectrum
Publication date: Nov 2017, volume: 54, issue:11, pages: 12 - 12
Publisher: IEEE
 
» On a Class of Optimization-Based Robust Estimators
Abstract:
In this paper, we consider the problem of estimating a parameter matrix from observations which are affected by two types of noise components: (i) a sparse noise sequence which, whenever nonzero can have arbitrarily large amplitude (ii) and a dense and bounded noise sequence of “moderate” amount. This is termed a robust regression problem. To tackle it, a quite general optimization-based framework is proposed and analyzed. When only the sparse noise is present, a sufficient bound is derived on the number of nonzero elements in the sparse noise sequence that can be accommodated by the estimator while still returning the true parameter matrix. While almost all the restricted isometry-based bounds from the literature are not verifiable, our bound can be easily computed through solving a convex optimization problem. Moreover, empirical evidence tends to suggest that it is generally tight. If in addition to the sparse noise sequence, the training data are affected by a bounded dense noise, we derive an upper bound on the estimation error.
Autors: Laurent Bako;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5990 - 5997
Publisher: IEEE
 
» On Control Lyapunov–Razumikhin Functions, Nonconstant Delays, Nonsmooth Feedbacks, and Nonlinear Sampled-Data Stabilization
Abstract:
A methodology for the design of stabilizers in the sample-and-hold sense for nonlinear retarded systems is provided. The methodology is based on control Lyapunov–Razumikhin functions. Fully nonlinear retarded systems with an arbitrary number of arbitrary time-varying time-delays of discrete and distributed type are covered by the theory developed here, as long as the map describing the dynamics is uniformly in time Lipschitz on bounded sets of the Banach state space and the Euclidean input space. The standard assumption that all involved time-delay signals are globally Lipschitz is introduced. It is assumed, for the system at hand, that there exist a control Lyapunov–Razumikhin function and a suitably defined induced steepest descent state feedback. Moreover, such state feedback has to satisfy a suitably weak Lipschitz property, uniformly in time and in any bounded subset of the Banach state space. Such weak Lipschitz property has the advantage to allow for discontinuities in the feedback, which arise, for instance, in sliding-mode control methodologies. The following fact is shown: the above steepest descent state feedback is a stabilizer in the sample-and-hold sense, that is, such feedback, if applied by suitably fast sampling and holding, guarantees practical semiglobal stability of the closed-loop system, with arbitrary small final target ball of the origin. The problem of nonavailability in the buffer device of past values of the system internal variables is solved by spline approximation methods, even in the case discontinuities arise in the state feedback.
Autors: Pierdomenico Pepe;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5604 - 5619
Publisher: IEEE
 
» On Distributed Computing for Functions With Certain Structures
Abstract:
The problem of distributed function computation is studied, where functions to be computed is not necessarily symbol-wise. A new method to derive a converse bound for distributed computing is proposed; from the structure of functions to be computed, information that is inevitably conveyed to the decoder is identified, and the bound is derived in terms of the optimal rate needed to send that information. The class of informative functions is introduced, and, for the class of smooth sources, the optimal rate for computing those functions is characterized. Furthermore, for i.i.d. sources with joint distribution that may not be full support, functions that are composition of symbol-wise function and the type of a sequence are considered, and the optimal rate for computing those functions is characterized in terms of the hypergraph entropy. As a byproduct, our method also provides a conceptually simple proof of the known fact that computing a Boolean function may require as large rate as reproducing the entire source.
Autors: Shigeaki Kuzuoka;Shun Watanabe;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7003 - 7017
Publisher: IEEE
 
» On General Properties of Eigenvalues and Eigenfunctions of a Sturm–Liouville Operator: Comments on “ISS With Respect to Boundary Disturbances for 1-D Parabolic PDEs”
Abstract:
In the paper “ISS with respect to boundary disturbances for 1-D parabolic PDEs” (IEEE Transactions on Automatic Control, vol. 61, pp. 3712–3724, 2016), input-to-state stability properties are established for 1-D spatially varying parabolic partial differential equations (PDEs) under certain assumptions, imposed on eigenvalues and eigenfunctions of an associated Sturm–Liouville operator. A key assumption on the absolute convergence of an associated Fourier series, composed of the normalized eigenfunctions and inverse eigenvalues of the Sturm–Liouville operator, is analyzed in the present note. General properties of the Sturm–Liouville operator are carried out to demonstrate that such a key assumption becomes redundant for the underlying PDEs with sign-definite sufficiently smooth coefficients.
Autors: Yury Orlov;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5970 - 5973
Publisher: IEEE
 
» On Generalized Spatial Modulation Aided Millimeter Wave MIMO: Spectral Efficiency Analysis and Hybrid Precoder Design
Abstract:
The concept of generalized spatial modulation (GenSM) aided millimeter wave (mm-wave) multiple-input multiple-output (MIMO) has recently attracted substantial research interest, as it benefits from the large bandwidth of mm-wave MIMO, while maintaining a reduced number of radio frequency (RF) chains. However, due to the lack of precoding design, the preceding GenSM-aided mm-wave MIMO schemes suffered from severe performance loss. Inspired by the reduced-RF-chain structure making implementation cost low while maintaining the benefit of GenSM, in this paper, we incorporate the technique of hybrid precoding into GenSM-aided mm-wave MIMO, where a hybrid digital and analog precoding regime is proposed to enhance the system’s achievable rate. Moreover, a closed-form expression is proposed to provide an accurate approximation to the spectral efficiency (SE) achieved by the proposed scheme. The proposed expression is further simplified in the region of high signal-to-noise ratio (SNR). By exploiting the proposed SE expressions as low-complexity cost functions, two algorithms, i.e. the gradient ascent algorithm and the high-SNR approximation algorithm, are exploited to optimize the hybrid precoders in terms of SE maximization. Finally, numerical simulations are provided to substantiate the superior SE performance achieved by the proposed scheme over other GenSM-aided mm-wave MIMO schemes as well as the state-of-the-art mm-wave MIMO systems.
Autors: Longzhuang He;Jintao Wang;Jian Song;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7658 - 7671
Publisher: IEEE
 
» On Linear Precoding of Nonregenerative MIMO Relay Networks for Finite-Alphabet Source
Abstract:
Multiple input and multiple output (MIMO) relay could provide broader wireless coverage, better diversity, and higher throughput. Most existing precoder designs for either source or relay node are based on the assumption of Gaussian input signals. However, recent works have revealed possible performance loss of MIMO systems originally optimized for Gaussian source signals when applied to practical finite-alphabet source signals. In this work, we investigate the design problem of joint MIMO precoding for wireless two-hop nonregenerative cooperative relay networks under finite-alphabet source signals. We identify several structural properties of optimal precoders. Specifically, we provided the optimal left singular vectors of the relay precoder, and proved the convexity of mutual information with respect to the square of relay precoder singular value. These results generalize the two-hop relay networks in Gaussian input assumption to the cooperative relay networks in arbitrary finite-alphabet input signals. Furthermore, we propose gradient-based numerical iterative optimization algorithms not only for arbitrary finite-alphabet source signal precoding but also for cooperative relay networks which may or may not have a direct source to destination link. Our results demonstrate substantial performance improvement over existing precoder designed traditionally under Gaussian input assumption, which indicates that the waterfilling based precoding strategy is not suitable for finite-alphabet constellation source inputs.
Autors: Xiao Liang;Zhi Ding;Chengshan Xiao;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9761 - 9775
Publisher: IEEE
 
» On Methods to Determine Bounds on the $Q$ -Factor for a Given Directivity
Abstract:
This paper revisit and extend the interesting case of bounds on the -factor for a given directivity for a small antenna of arbitrary shape. A higher directivity in a small antenna is closely connected with a narrow impedance bandwidth. The relation between bandwidth and a desired directivity is still not fully understood, not even for small antennas. Initial investigations in this direction have related the radius of a circumscribing sphere to the directivity, and bounds on the -factor have also been derived for a partial directivity in a given direction. In this paper, we derive lower bounds on the -factor for a total desired directivity for an arbitrarily shaped antenna in a given direction as a convex problem using semidefinite relaxation (SDR) techniques. We also show that the relaxed solution is also a solution of the original problem of determining the lower -factor bound for a total desired directivity. SDR can also be used to relax a class of other interesting nonconvex constraints in antenna optimization, such as tuning, losses, and front-to-back ratio. We compare two different new methods to determine the lowest -factor for arbitrary-shaped antennas for a given total directivity. We also compare our results with full electromagnetic simulations of a parasitic element antenna with high directivity.
Autors: B.L.G. Jonsson;Shuai Shi;Lei Wang;Fabien Ferrero;Leonardo Lizzi;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 5686 - 5696
Publisher: IEEE
 
» On Minimal Steiner Maximum-Connected Subgraph Queries
Abstract:
Given a graph and a set of query nodes, we examine the Steiner Maximum-Connected Subgraph (SMCS) problem. The SMCS, or 's induced subgraph that contains with the largest connectivity, can be useful for customer prediction, product promotion, and team assembling. Despite its importance, the SMCS problem has only been recently studied. Existing solutions evaluate the maximum SMCS, whose number of nodes is the largest among all the SMCSs of . However, the maximum SMCS, which may contain a lot of nodes, can be difficult to interpret. In this paper, we investigate the minimal SMCS , which is the minimal subgraph of with the maximum connectivity containing . The minimal SMCS contains much fewer nodes than its maximum counterpart, and is thus easier to be understood. However, the minimal SMCS can be costly to evaluate. We thus propose effici- nt Expand-Refine algorithms, as well as their approximate versions with accuracy guarantees. We further develop a cache-based processing model to improve the efficiency for an important case when consists of a single node. Extensive experiments on large real and synthetic graph datasets validate the effectiveness and efficiency of our approaches.
Autors: Jiafeng Hu;Xiaowei Wu;Reynold Cheng;Siqiang Luo;Yixiang Fang;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Nov 2017, volume: 29, issue:11, pages: 2455 - 2469
Publisher: IEEE
 
» On Multi-Source Networks: Enumeration, Rate Region Computation, and Hierarchy
Abstract:
Recent algorithmic developments have enabled computers to automatically determine and prove the capacity regions of small hypergraph networks under network coding. A structural theory relating network coding problems of different sizes is developed to make the best use of this newfound computational capability. A formal notion of network minimality is developed, which removes components of a network coding problem that are inessential to its core complexity. Equivalence between different network coding problems under relabeling is formalized via group actions, an algorithm which can directly list single representatives from each equivalence class of minimal networks up to a prescribed network size is presented. This algorithm, together with rate region software, is leveraged to create a database containing the rate regions for all minimal network coding problems with five or fewer sources and edges, a collection of 744119 equivalence classes representing more than 9 million networks. In order to best learn from this database, and to leverage it to infer rate regions and their characteristics of networks at scale, a hierarchy between different network coding problems is created with a new theory of combinations and embedding operators.
Autors: Congduan Li;Steven Weber;John MacLaren Walsh;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7283 - 7303
Publisher: IEEE
 
» On Projected Stochastic Gradient Descent Algorithm with Weighted Averaging for Least Squares Regression
Abstract:
The problem of least squares regression of a -dimensional unknown parameter is considered. A stochastic gradient descent based algorithm with weighted iterate-averaging that uses a single pass over the data is studied and its convergence rate is analyzed. We first consider a bounded constraint set of the unknown parameter. Under some standard regularity assumptions, we provide an explicit upper bound on the convergence rate, depending on the variance (due to the additive noise in the measurements) and the size of the constraint set. We show that the variance term dominates the error and decreases with rate , while the term that is related to the size of the constraint set decreases with rate . We then compare the asymptotic ratio between the convergence rate of the proposed scheme and the empirical risk minimizer (ERM) as the number of iterations approaches infinity. We show that for all when the random entries of the sensing vector are uncorrelated and identically distributed. We further improve the upper bound by showing that for the case of and unbounded parameter set when the random sensing entries are equal across time. Simulation results demonstrate strong performance of the algorithm as compared to existing methods, and coincide with $rho leq 4/3$ even for large in practice.
Autors: Kobi Cohen;Angelia Nedić;R. Srikant;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5974 - 5981
Publisher: IEEE
 
» On Ransomware and Envisioning the Enemy of Tomorrow
Abstract:
We warned the public more than 20 years ago that cryptoviral extortion would pose a major threat to users, a threat that has been realized with the advent of Bitcoin but largely neglected until recently. We believe that a reactive mindset along with group conformity are partly to blame for this oversight and, moreover, are negatively impacting secure systems research. This presents a recipe for disaster, for while cryptoviral extortion is wreaking havoc on the surface, covert cryptovirology attacks are likely gathering strength within the shadows.
Autors: Adam L. Young;Moti Yung;
Appeared in: Computer
Publication date: Nov 2017, volume: 50, issue:11, pages: 82 - 85
Publisher: IEEE
 
» On the Correlation Distribution for a Niho Decimation
Abstract:
Let be a prime, and with , and . In this paper, the correlation distribution between a -ary -sequence of period and its -decimation sequence is investigated in a unified approach. Some results for the binary case are extended to the general case. It is shown that the problem of determining the correlation distribution for can be reduced to that of solving two combinatorial problems related to the unit circle of the finite field . For an arbitrary odd prime , it seems difficult to solve these two problems. However, for , by studying the weight distribution of the ternary Zetterberg code and counting the numbers of solutions of some equations over , the two problems are solved, and thus, the corresponding correlation distribution for is completely determined. It is - oteworthy that this is the first time that the correlation distribution for a non-binary Niho decimation has been determined since 1976.
Autors: Yongbo Xia;Nian Li;Xiangyong Zeng;Tor Helleseth;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7206 - 7218
Publisher: IEEE
 
» On the Covariance Matrix and Diversity Performance Evaluation of Compact Multiport Antenna Systems
Abstract:
In this communication, we present a new electromagnetic methodology that determines the covariance matrix of compact multiport antenna (MPA) systems at the early design stage. Further insight into this field is provided, as contrary to existing methodologies, it rigorously relies on the reciprocity principle of MPA systems. Thus, the impact of propagation environment, termination conditions, and MPA radiation characteristics as independent factors affecting performance is physically incorporated. Provided the availability of mathematical expressions for the cumulative distribution function and probability density function of received signal-to-noise ratio (SNR), performance can then be analytically studied via the diversity antenna gain (DAG) in terms of: 1) SNR enhancement at a specific outage probability (OP) level (that is DAG-OP) and 2) average SNR reduction for achieving a specific average bit error rate (BER) (that is DAG-BER). Illustrative examples with performance evaluation of compact MPA systems are presented. The adopted diversity technique is the transmit antenna selection/maximal ratio combining, which is analytically studied employing realistic MPA systems for the first time. Comparisons with existing published results further demonstrate the validity and usefulness of the proposed methodology.
Autors: Vasilis Papamichael;Petros Karadimas;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6140 - 6144
Publisher: IEEE
 
» On the Decidability and Complexity of Diagnosability for Labeled Petri Nets
Abstract:
In this paper, we investigate the decidability and complexity of the fault diagnosis problem in unbounded labeled Petri nets. First, we show that checking diagnosability for unbounded Petri nets is decidable. We present a new necessary and sufficient condition for diagnosability, which can be reduced to a model checking problem for unbounded Petri nets. Then, we show that checking diagnosability for unbounded Petri nets is EXPSPACE-complete. This complexity result is further extended to various subclasses of Petri nets. To the best of our knowledge, this is the first paper that establishes decidability and complexity results for diagnosability of unbounded Petri nets.
Autors: Xiang Yin;Stéphane Lafortune;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5931 - 5938
Publisher: IEEE
 
» On the Design and Construction Assessments of a Permanent-Magnet-Assisted Synchronous Reluctance Motor
Abstract:
By appropriately inserting ferrite magnets into the rotor of a synchronous reluctance motor (SynRM), the machine operational power factors and torque outputs can be improved. With specific rotor structures to accommodate those ferrites, many of these permanent-magnet-assisted SynRMs (PMA-SynRMs) have been proposed to comply the expected operational objectives. For construction convenience, the ferrites that being inserted into the flux barriers of these PMA-SynRMs are generally in rectangular shapes; hence, some adjustments on the rotor flux barriers and additional bridges are required. Such changes will inevitably affect the performance of the original SynRMs with optimized rotor structures, and these tradeoffs are thus to be recovered by parts of those adopted ferrites. This paper will provide an evaluation index that can characterize the performance of PMA-SynRMs with different volume compositions of the ferrites, along with the impact assessments of the SynRMs with modified flux barriers such that those ferrites can be properly allocated. Based on the designs obtained from thorough 3-D finite-element analyses, a 3-hp PMA-SynRM will be constructed and the related experimental measurements will also be supported to validate the design adequacies.
Autors: Cheng-Tsung Liu;Ta-Yin Luo;Pei-Chun Shih;Sheng-Chan Yen;Hsin-Nan Lin;Yu-Wei Hsu;Chang-Chou Hwang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» On the Design of Maximal-Rate Shape-Preserving $2times 2$ and $3times 3$ Space-Time Codes for Noncoherent Energy-Detection-Based PPM Communications
Abstract:
In this paper, we propose novel and noncoherent space-time (ST) codes for impulse-radio ultra-wideband communications with pulse position modulation (PPM). The code design is based on existing coherent ST codes, where the associated constellation is confined in order to achieve full diversity with analog energy detectors. A comprehensive performance analysis guides this confinement and highlights the maximum rates that can be achieved by this specific layered code word structure with two and three transmit antennas. The proposed codes attain these maximum rates without introducing any expansion to the unipolar PPM signal set.
Autors: Chadi Abou-Rjeily;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7432 - 7445
Publisher: IEEE
 
» On the Effect of Spatially Non-Disjoint Training and Test Samples on Estimated Model Generalization Capabilities in Supervised Classification With Spatial Features
Abstract:
In this letter, we establish two sampling schemes to select training and test sets for supervised classification. We do this in order to investigate whether estimated generalization capabilities of learned models can be positively biased from the use of spatial features. Numerous spatial features impose homogeneity constraints on the image data, whereby a spatially connected set of image elements is attributed identical feature values. In addition to a frequent occurrence of intrinsic spatial autocorrelation, this leads to extrinsic spatial autocorrelation with respect to the image data. The first sampling scheme follows a spatially random partitioning into training and test sets. In contrast to that, the second strategy implements a spatially disjoint partitioning, which considers in particular topological constraints that arise from the deployment of spatial features. Experimental results are obtained from multi- and hyperspectral acquisitions over urban environments. They underline that a large share of the differences between estimated generalization capabilities obtained with the spatially disjoint and non-disjoint sampling strategies can be attributed to the use of spatial features, whereby differences increase with an increasing size of the spatial neighborhood considered for computing a spatial feature. This stresses the necessity of a proper spatial sampling scheme for model evaluation to avoid overoptimistic model assessments.
Autors: Christian Geiß;Patrick Aravena Pelizari;Henrik Schrade;Alexander Brenning;Hannes Taubenböck;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2008 - 2012
Publisher: IEEE
 
» On the Evaluation of Different High-Performance Computing Platforms for Hyperspectral Imaging: An OpenCL-Based Approach
Abstract:
Hyperspectral imaging systems are a powerful tool for obtaining surface information in many different spectral channels that can be used in many different applications. Nevertheless, the huge amount of information provided by hyperspectral images also has a downside, since it has to be processed and analyzed. For such purpose, parallel hardware devices, such as field-programmable gate arrays (FPGAs) and graphic processing units (GPUs), are typically used, especially for hyperspectral imaging applications under real-time constraints. However, developing hardware applications typically requires expertise in the specific targeted device, as well as in the tools and methodologies that can be used to perform the implementation of the desired algorithms in that device. In this scenario, the Open Computing Language (OpenCL) emerges as a very interesting solution in which a single high-level language can be used to efficiently develop applications in multiple and different hardware devices. In this work, the parallel Fast Algorithm for Linearly Unmixing Hyperspectral Images (pFUN) has been implemented in two different NVIDIA GPUs, the GeForce GTX 980 and the Tesla K40c, using OpenCL. The obtained results are compared with the results provided by the previously developed NVIDIA CUDA implementation of the pFUN algorithm for the same GPU devices for comparing the efficiency of OpenCL against a more specific synthesis design language for the targeted hardware devices, such as CUDA is for NVIDIA GPUs. Moreover, the FUN algorithm has also been implemented into a Bitware Stratix V Altera FPGA, using OpenCL, for comparing the results that can be obtained using OpenCL when targeting different devices and architectures. The obtained results demonstrate the suitability of the followed methodology in the sense that it allows the achievement of efficient FPGA and GPU implementations able to cope with the stringent requirements imposed by hyperspectral imaging systems.
Autors: Raúl Guerra;Ernestina Martel;Jehandad Khan;Sebastián López;Peter Athanas;Roberto Sarmiento;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 4879 - 4897
Publisher: IEEE
 
» On the Exact and Approximate Eigenvalue Distribution for Sum of Wishart Matrices
Abstract:
The sum of Wishart matrices has an important role in multiple-input multiple-output (MIMO) multiple access channel (MAC) and MIMO relay channel. In this paper, we present a new closed-form expression for the marginal density of one of the unordered eigenvalues of a sum of complex central Wishart matrices having covariance matrices proportional to the identity matrix. The expression is general and allows for any set of linear coefficients. The derived expression is used to obtain the ergodic sum-rate capacity for the MIMO-MAC and MIMO relay cases, both as closed-form expressions. We also present a very simple expression to approximate the sum of Wishart matrices by one equivalent Wishart matrix. The agreement between the exact eigenvalue distribution and numerical simulations is perfect, whereas for the approximate solution the difference is indistinguishable.
Autors: Gabriel Fernando Pivaro;Santosh Kumar;Gustavo Fraidenraich;Claudio Ferreira Dias;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10537 - 10541
Publisher: IEEE
 
» On the Hardware Implementation of MRAM Physically Unclonable Function
Abstract:
Intrinsic properties of magnetic tunnel junctions (MTJs) are exploited for low-power security electronics. The combination of: 1) fast and nonvolatile storage; 2) stochastic nature of subcritical switching; and 3) random variation in the magnetic anisotropy of MTJ make MRAM array ideal for implementing physically unclonable function (PUF). We develop two bit-pattern randomization procedures, one of which can be exercised at wafer level in process line, while the other can be completed in the in-line tester. The procedures generate unpredictable and unclonable bit patterns in a spin-transfer torque (STT)-MRAM array and store them securely in the array. We show the resistance of MTJ is stable through rounds of thermal baking, the readback from the PUF shows no ambiguity from 25 °C to 75 °C. A single embedded STT-MRAM PUF can cover many needs of security electronics.
Autors: Yu-Sheng Chen;Ding-Yeong Wang;Yu-Chen Hsin;Kai-Yu Lee;Guan-Long Chen;Shan-Yi Yang;Hsin-Han Lee;Yao-Jen Chang;I-Jung Wang;Pei-Hua Wang;Chih-I Wu;D. D. Tang;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4492 - 4495
Publisher: IEEE
 
» On the Homogeneity and Isotropy of Non-Grain-Oriented Electrical Steel Sheets for the Modeling of Basic Magnetic Properties from Microstructure and Texture
Abstract:
Laminations of non-grain-oriented (NO) electrical steel grades for magnetic cores of electrical machines should feature homogenous magnetic properties within the entire sheet plane. Basic empirical models have been introduced to estimate and correlate magnetic properties with microstructural material parameters. In these considerations, the steel sheets are generally considered to be homogenous, i.e., orientation dependence and variations across the sheet thickness are often disregarded. Whether or not, these simplifications are justified and how grain size and texture are described most suitable for correlations with magnetic properties is the focus of this paper discussing four industrial NO steel grades.
Autors: Nora Leuning;Simon Steentjes;Kay Hameyer;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» On the Maximum Burst-Correcting Capability of Cyclic Hsu–Kasami–Chien Codes
Abstract:
Hsu–Kasami–Chien (HKC) codes are a class of cyclic codes that can correct either burst or random errors. This letter studies the maximum burst-correcting capability of HKC codes. A necessary and sufficient condition for a -burst-correcting cyclic HKC code is given and simplified as a generalized one for Fire codes. An upper bound on the burst-correcting capability of HKC codes is derived, which improves upon a previous bound. Explicit examples of HKC codes are presented. A design guideline for constructing HKC codes with given burst-error and random-error correcting capabilities is presented.
Autors: Wei Zhou;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2352 - 2355
Publisher: IEEE
 
» On the Mechanisms Governing Spurious Tone Injection in Fractional PLLs
Abstract:
In fractional phase-locked loop driven by modulators there can be spurious tones in the power spectral density (PSD) of output signals even if the PSDs of the sequences used to drive the frequency divider are spur-free. This is due to undesirable nonlinear effects notably occurring in the charge pump (CP). In this brief, we focus on static and dynamic mismatch of the CP and its interaction with the digital delay usually present in the reset path of the phase-frequency detector. Despite the presence of nonlinearities, we show that spurs may not appear, and mechanisms governing their existence are unveiled. A compact and simple model is presented allowing the onset of spurs and their magnitude to be reliably estimated.
Autors: Federico Bizzarri;Angelo Maurizio Brambilla;Sergio Callegarisergio;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Nov 2017, volume: 64, issue:11, pages: 1267 - 1271
Publisher: IEEE
 
» On the Output of Nonlinear Systems Excited by Discrete Prolate Spheroidal Sequences
Abstract:
The discrete prolate spheroidal sequences (DPSSs)—a set of optimally bandlimited sequences with unique properties—are important to applications in both science and engineering. In this work, properties of nonlinear system response due to DPSS excitation are reported. In particular, the sequences are shown to be approximately orthogonal after passing through a nonlinear, multiple-input multiple-output dynamical system under quite general conditions. This work quantifies these conditions in terms of constraints upon the higher-order generalized transfer functions characterizing the Volterra expansion of a MIMO system, the Volterra order of the system, and the DPSS bandwidth parameter and time-bandwidth parameter . The approximate system output orthogonality allows multiple-input, multiple-output characterization of the linear narrowband response of a nonlinear system using simultaneous, DPSS excitation.
Autors: Kyle Q. Lepage;ShiNung Ching;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5780 - 5787
Publisher: IEEE
 
» On the Performance of a Multi-Tier NOMA Strategy in Coordinated Multi-Point Networks
Abstract:
Non-orthogonal multiple access (NOMA) is a promising multiple access technique for fifth-generation mobile networks. In this letter, a novel multi-tier NOMA (TNOMA) scheme is proposed for a coordinated multi-point (CoMP) network. This TNOMA scheme aims to improve the coverage of high data rate services in a CoMP network, especially for the case when access points are not able to serve all of the users in the network. To bench-mark the TNOMA scheme against one-tier NOMA-CoMP, the effective sum-rate performances are evaluated. The results show that the performance difference between one-tier only NOMA-CoMP and multi-tier NOMA-CoMP is influenced by the transmission-nodes-selection threshold value () and the target data rate.
Autors: Yue Tian;Andrew Nix;Mark Beach;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2448 - 2451
Publisher: IEEE
 
» On the Performance of IEEE 802.11p and LTE-V2V for the Cooperative Awareness of Connected Vehicles
Abstract:
To improve safety on the roads, next-generation vehicles will be equipped with short-range communication technologies. Many applications enabled by such communication will be based on a continuous broadcast of information about the own status from each vehicle to the neighborhood, often referred as cooperative awareness or beaconing. Although the only standardized technology allowing direct vehicle-to-vehicle (V2V) communication has been IEEE 802.11p until now, the latest release of long-term evolution (LTE) included advanced device-to-device features designed for the vehicular environment (LTE-V2V) making it a suitable alternative to IEEE 802.11p. Advantages and drawbacks are being considered for both technologies, and which one will be implemented is still under debate. The aim of this paper is thus to provide an insight into the performance of both technologies for cooperative awareness and to compare them. The investigation is performed analytically through the implementation of novel models for both IEEE 802.11p and LTE-V2V able to address the same scenario, with consistent settings and focusing on the same output metrics. The proposed models take into account several aspects that are often neglected by related works, such as hidden terminals and capture effect in IEEE 802.11p, the impact of imperfect knowledge of vehicles position on the resource allocation in LTE-V2V, and the various modulation and coding scheme combinations that are available in both technologies. Results show that LTE-V2V allows us to maintain the required quality of service at even double or more the distance than IEEE 802.11p in moderate traffic conditions. However, due to the half-duplex nature of devices and the structure of LTE frames, it shows lower capacity than IEEE 802.11p if short distances and very high vehicle density are targeted.
Autors: Alessandro Bazzi;Barbara M. Masini;Alberto Zanella;Ilaria Thibault;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10419 - 10432
Publisher: IEEE
 
» On the Robust and Stable Flowshop Scheduling Under Stochastic and Dynamic Disruptions
Abstract:
In this paper, we consider a permutation flowshop scheduling problem with the total flow time as the schedule performance measure. A proactive–reactive approach is designed to simultaneously deal with stochastic disruptions (e.g., machine breakdowns) and dynamic events (e.g., newly arriving jobs and delay in job availability). In the proactive stage, the stochastic machine breakdown is hedged against the construction of a robust and stable baseline schedule. This schedule is either optimized by incorporating uncertainty into two surrogate measures or obtained by simulation. Robustness is measured by the expected schedule performance, while stability is measured by the aggregation of dissatisfactions of manager, shopfloor operator, and customers using the prospect theory. In the reactive stage, we assume that the stochastic and dynamic disruptions concurrently occur. Unlike the simple right-shifting method, a more effective rescheduling approach is proposed to balance the realized schedule performance with stability. A common issue in these two stages is the conflict between objectives. Thus, we propose a hybridization strategy that successfully enhances the classic Non-dominated Sorting Genetic Algorithm (NSGA-II and the hybridized algorithm outperforms NSGA-II, multiobjective evolutionary algorithm based on decomposition, and multiobjective memetic algorithms designed for deterministic scheduling problems. Finally, extensive computational studies on the Taillard flowshop benchmark instances are conducted to illustrate the effectiveness of the proposed proactive–reactive approach and the algorithm hybridization strategy.
Autors: Feng Liu;Shengbin Wang;Yuan Hong;Xiaohang Yue;
Appeared in: IEEE Transactions on Engineering Management
Publication date: Nov 2017, volume: 64, issue:4, pages: 539 - 553
Publisher: IEEE
 
» On the Secrecy Performance Analysis of SIMO Systems Over $kappa$ – $mu$ Fading Channels
Abstract:
In this letter, the secrecy performance of single-input multiple-output systems over the generalized – fading channels is analyzed. Novel expressions for the average secrecy capacity and the secure outage probability (SOP) are derived. Moreover, simple and explicit expressions of the asymptotic SOP at high signal-to-noise ratio are given in an effort to gain some valuable insights on how various system parameters affect the secrecy performance. The proposed mathematical analysis is compared with Monte–Carlo simulation to verify the accuracy of the derivation.
Autors: Jules M. Moualeu;Walaa Hamouda;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2544 - 2547
Publisher: IEEE
 
» On the Simulation of Complex Visibilities in Imaging Radiometry by Aperture Synthesis
Abstract:
The basic observables of an imaging interferometer by aperture synthesis are the complex visibilities. Under some conditions, they can be simulated with the aid of the van Cittert–Zernike theorem. However, owing to underlying assumptions, some important effects that may alter them cannot be taken into account. This paper is devoted to the numerical simulation of complex visibilities without any reference to the van Cittert–Zernike theorem, in such a way that these effects can be taken into account. The emission from an extended source is modeled using a linear superposition of random waves emitted by a collection of point sources, which are all assumed to behave like black bodies at thermal equilibrium. These random waves are numerically generated with the aid of white noises filtered in such a way that their power spectral densities follow the shape of Planck distributions at the temperature of the point sources over a wide range of frequencies. The radio signal is then transported to the antennas, where the voltage patterns are taken into account as well as the filters response of the bandpass receivers. It is, therefore, sent to the correlator unit for being cross-correlated. From emission to correlation, perturbing effects can be introduced at any time. To illustrate this modeling method, numerical simulations are carried out in the L-band around 1413.5 MHz in reference to the SMOS-next project led by the French Space Agency. The results are discussed and compared with the estimates provided by the van Cittert–Zernike theorem. Owing to the amount of calculations to be performed, massive parallel architectures like that found in GPU have been required.
Autors: Eric Anterrieu;François Cabot;Ali Khazaal;Yann H. Kerr;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 4666 - 4676
Publisher: IEEE
 
» On the Temporal Effects of Mobile Blockers in Urban Millimeter-Wave Cellular Scenarios
Abstract:
Millimeter-wave (mmWave) propagation is known to be severely affected by the blockage of the line-of-sight (LoS) path. In contrast to microwave systems, at shorter mmWave wavelengths such blockage can be caused by human bodies, where their mobility within environment makes wireless channel alternate between the blocked and non-blocked LoS states. Following the recent 3GPP requirements on modeling the dynamic blockage as well as the temporal consistency of the channel at mmWave frequencies, in this paper, a new model for predicting the state of a user in the presence of mobile blockers for representative 3GPP scenarios is developed: Urban micro cell street canyon and park/stadium/square. It is demonstrated that the blockage effects produce an alternating renewal process with exponentially distributed non-blocked intervals, and blocked durations that follow the general distribution. The following metrics are derived 1) the mean and the fraction of time spent in blocked/non-blocked state, 2) the residual blocked/non-blocked time, and 3) the time-dependent conditional probability of having blockage/no blockage at time given that there was blockage/no blockage at time . The latter is a function of the arrival rate (intensity), width, and height of moving blockers, distance to the mmWave access point (AP), as well as the heights of the AP and the user device. The proposed model can be used for system-level characterization of mmWave cellular communication systems. For example, the optimal height and the maximum coverage radius of the mmWave APs are derived, while satisfying the required mean data rate constraint. The system-level simulations corroborate that the use of the proposed method considerably reduces the modeling complexity.
Autors: Margarita Gapeyenko;Andrey Samuylov;Mikhail Gerasimenko;Dmitri Moltchanov;Sarabjot Singh;Mustafa Riza Akdeniz;Ehsan Aryafar;Nageen Himayat;Sergey Andreev;Yevgeni Koucheryavy;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10124 - 10138
Publisher: IEEE
 
» On the Time-Dependent Transport Mechanism Between Surface Traps and the 2DEG in AlGaN/GaN Devices
Abstract:
The physical mechanisms involved in the trapping and de-trapping processes associated with surface donor traps in gallium nitride (GaN) transistors are discussed in this paper. The paper challenges the conventional transient techniques adopted for extrapolating the trap energy level via experiments and TCAD simulations. Transient TCAD simulations were employed to reproduce the time-dependent electrical behavior of a metal-on-insulator field-effect transistor and explain the influence of the electric field and energy barrier on the transient time associated with the trapping and de-trapping mechanisms of surface traps. The comparison between three test structures and the relative variation of the trapping and de-trapping times with the bias and trap parameters leads to the suggestion of a proposed test structure and bias configuration to accurately extrapolate the energy level of surface traps in GaN transistors.
Autors: Giorgia Longobardi;Florin Udrea;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4415 - 4423
Publisher: IEEE
 
» On the Tradeoff Region of Secure Exact-Repair Regenerating Codes
Abstract:
We consider the secure exact-repair regenerating code problem, which generalizes the exact-repair regenerating code problem with the additional constraint that the stored file needs to be kept information-theoretically secure against an eavesdropper, who can access the data transmitted to regenerate a total of different failed nodes. For all known results on this problem, the achievable tradeoff regions between the normalized storage capacity and repair bandwidth have a single corner point, achieved by a scheme proposed by Shah, Rashmi, and Kumar (the SRK point). Since the achievable tradeoff regions of the exact-repair regenerating code problem without any secrecy constraints are known to have multiple corner points in general, these existing results suggest a phase-change-like behavior, i.e., enforcing a secrecy constraint () immediately reduces the tradeoff region to one with a single corner point. In this paper, we first show that when the secrecy parameter is sufficiently large, the SRK point is indeed the only corner point of the tradeoff region. However, when is small, we show that the tradeoff region can in fact have multiple corner points. In particular, we establish a precise characterization of the tradeoff region for the (7, 6, 6, 1) problem, which has exactly two corner points. Thus, a smooth transition, instead of a phase-change-type of transition, should be expected as the secrecy constraint is gradually strengthened.
Autors: Shuo Shao;Tie Liu;Chao Tian;Cong Shen;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7253 - 7266
Publisher: IEEE
 
» On Theoretical Trajectory Planning of Multiple Drones To Minimize Latency in Search-and-Reconnaissance Operations
Abstract:
Following the recent advances in drone technologies, various algorithmic optimization problems related to the effective operation of drones are drawing lots of attentions. This paper considers two interesting multiple-drone-assisted search-and-reconnaissance scenarios, in each of which, the trajectory optimization of multiple drones is of great significance to minimize the latency in the system. In the first scenario, multiple drones, whose moments of mobilization are not necessarily the same, are trying to urgently collect intelligence from a given point of interest, and we would like to minimize the task completion time, i.e., the time period between the moment that the first drone commences its operation to the moment that the intelligence from all of the points are collected, by optimizing their trajectories. In the second scenario, multiple drones with different speeds, are hovering around the same routes to regularly collect intelligence from highly geographically-diversified points of interest over an extended time period, and we would like to minimize the worst-case data refreshment rate, the largest time gap between two consecutive observations over the same point of interest. In this paper, we formally define each problem, prove its NP-hardness, and propose an approximation algorithm for it. We also conduct a simulation to study the performance of our result.
Autors: Donghyun Kim;Lirong Xue;Deying Li;Yuqing Zhu;Wei Wang;Alade O. Tokuta;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Nov 2017, volume: 16, issue:11, pages: 3156 - 3166
Publisher: IEEE
 
» On-Chip Magnetic Nanoparticle Manipulation and Trapping for Biomedical Applications
Abstract:
Biomedical applications and point-of-use devices often rely on nanoparticle concentration strategies. In this paper, on-chip magnetic trapping and manipulation of 300–500 nm superparamagnetic nanoparticles are achieved using thin-film planar circular copper coils. The trap configuration combining a central coil surrounded by four other coils, all connected in series, successfully enables simultaneous attraction and repulsion, enhancing concentration of magnetic nanoparticle (MNP). The simultaneous attraction and repulsion has advantages over static permanent magnets, where unidirectional actuation allows either attraction or repulsion. Because the distance between traps and the MNP is large (hundred micrometer), large electric currents up to 500 mA are needed to achieve fields of the order of hundreds of microtesla, which requires thermal management. Joule heating is effectively tackled by resorting to a novel cooling scheme comprising triangular microchannels milled onto copper substrates. Experimental results combining thermal surface mapping, magnetic field mapping, and optical (fluorescence microscope) observations could validate the trapping efficacy of Estapor microspheres functionalized with BODIPY 515 fluorophores.
Autors: Vania Silverio;Maria J. López-Martínez;Fernando Franco;Miguel Amaral;Joao Gaspar;Susana Cardoso;Paulo P. Freitas;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» On-Orbit Characterization of the MODIS SDSM Screen for Solar Diffuser Degradation Estimation
Abstract:
Moderate Resolution Imaging Spectroradiometer (MODIS) reflective solar bands (RSBs) are calibrated on-orbit using a solar diffuser (SD) with its degradation tracked by an onboard SD stability monitor (SDSM). The SDSM has nine detectors with wavelengths from 0.41 to 0.94 . It is operated during each scheduled SD calibration event, making alternate observations of the sun and the SD. Due to erroneous design parameters, which led to the misalignment of the key elements in the SDSM, there are significant ripples in the sun view responses as the solar viewing angle changes. At the mission beginning, the effect of the ripples was eliminated by normalizing each SDSM detector response to the response of detector 9 (D9) at 0.94 , assuming that D9 had no degradation. However, D9 degradation increases over MODIS operation times. Degradation of up to 2% has recently been observed in D9 for the Terra MODIS. A newly implemented approach reduces the sun view ripples using a lookup table constructed using SDSM data carefully selected from a short period early in the mission lifetime. In this paper, we provide an overview of different approaches that have been applied over the years by the MODIS Characterization Support Team to track the on-orbit SD degradation. We evaluate the overall SD and SDSM on-orbit performance for both Terra and Aqua MODIS, as well as the impact on the MODIS RSB calibration uncertainty.
Autors: Hongda Chen;Xiaoxiong Xiong;Amit Angal;Kevin A. Twedt;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6456 - 6467
Publisher: IEEE
 
» On-Orbit Line Spread Function Estimation of the SNPP VIIRS Imaging System From Lake Pontchartrain Causeway Bridge Images
Abstract:
The visible infrared imaging radiometer suite (VIIRS) instrument was launched on October 28, 2011 onboard the Suomi National Polar-Orbiting Partnership (SNPP) satellite. The VIIRS instrument is a whiskbroom system with 22 spectral and thermal bands split between 16 moderate resolution bands (M-bands), five imagery resolution bands (I-bands), and a day–night band. In this study, we estimate the along-scan line spread function (LSF) of the I-bands and M-bands based on measurements performed on images of the Lake Pontchartrain Causeway Bridge. In doing so, we develop a model for the LSF that closely matches the prelaunch laboratory measurements. We utilize VIIRS images co-geolocated with a Landsat TM image to precisely locate the bridge linear feature in the VIIRS images as a linear best fit to a straight line. We then utilize nonlinear optimization to compute the best fit equation of the VIIRS image measurements in the vicinity of the bridge to the developed model equation. From the found parameterization of the model equation, we derive the full-width at half-maximum as an approximation of the sensor field of view for all bands, and compare these on-orbit measured values with prelaunch laboratory results.
Autors: James C. Tilton;Robert E. Wolfe;Guoqing Lin;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 5056 - 5072
Publisher: IEEE
 
» Open-Contour Tracking Using a New State-Space Model and Nonrigid Motion Training
Abstract:
Object tracking in a video sequence is usually achieved by tracking the bounding box over the object or the object’s boundary, each of which has somewhat different applications. In this paper, we present a new open-contour tracking algorithm based on a Bayesian framework in which the contour is a part of the object’s boundary. We first propose a new state-space model for the representation of contours, which can handle the rigid and nonrigid motions of contours independently. This model enables us to focus on the nonrigid motions during the training, and the model works for challenging rigid motion scenarios. In addition, for the robust tracking of contours, we propose a measurement function that considers the contrast on object boundaries, target appearance, and temporal coherence. We applied the proposed method to two kinds of open-contours targets, and the experimental results show that the proposed method achieves superior performance to the conventional contour tracking methods. The proposed method is also compared with recent bounding box tracking methods for the object tracking purposes, and the comparison shows that the proposed method works robustly to fast motions and yields a more accurate estimate of an object’s location than the conventional bounding box tracking methods.
Autors: Seon Heo;Hyung Il Koo;Nam Ik Cho;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Nov 2017, volume: 27, issue:11, pages: 2355 - 2366
Publisher: IEEE
 
» Operating Waterside: Interesting Facts About How It Was Done [History]
Abstract:
Waterside was an iconic generating station built by the New York Edison Company and later operated by the Consolidated Edison Company of New York. It served as a primary source of electric power for Manhattan island throughout the 20th century. The following is not an exhaustive technical history of the station but, rather, a collection of interesting facts regarding procedures involved in operating this huge facility over the decades of its existence.
Autors: Thomas J. Blalock;
Appeared in: IEEE Power and Energy Magazine
Publication date: Nov 2017, volume: 15, issue:6, pages: 94 - 108
Publisher: IEEE
 
» Operation Strategy of Multi-Energy Storage System for Ancillary Services
Abstract:
Energy storage systems (ESSs) used for ancillary purposes in power systems have different capacities and output characteristics, and so need to be scheduled and operated together based on their state of charge rather than individually. This paper proposes a simple but effective method to allocate the energy required for spinning reserve or frequency regulation, properly to each ESS within a multi-ESS with the aim of improving system reliability. For this, an ESS reliability model is first proposed, and the reliability of the entire system is then evaluated using reliability models for other utilities such as conventional generators and renewable energy sources. To better demonstrate the improvement in reliability, two new reliability indices are introduced besides the existing indices: loss of frequency probability and loss of duration probability. Through case studies, it is shown that the required power is more effectively distributed across each ESS by the allocation method and thus the method can contribute to securing more spinning reserve and alleviating more frequency fluctuation, rather than the conventional method.
Autors: Wook-Won Kim;Je-Seok Shin;Jin-O Kim;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4409 - 4417
Publisher: IEEE
 
» Operator Safety and Field Focality in Aluminum Shielded Transcranial Magnetic Stimulation
Abstract:
This paper aims at verifying the effectiveness of the transcranial magnetic stimulation treatment when a passive shield is introduced for the nursing staff safety. The analysis is developed through a modeling approach, splitting the solution of the field problem into two successive steps. The Duke anatomical model of the Virtual Family dataset is used to model both the patient head and the operator body. The investigations are performed by considering stimulators equipped with a circular spiral coil or a figure-of-eight shaped (FoE or butterfly) winding. The addition of the shield slightly reduces the induced electric field values, while increasing the field focality in the patient brain (especially with the circular coil), preserving the effectiveness of the treatment, anyway. On the operators’ side, the presence of a passive conductive shield significantly reduces the exposure levels.
Autors: Mauro Zucca;Oriano Bottauscio;Mario Chiampi;Luca Zilberti;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Optical Emission Spectrum Processing Using Wavelet Compression During Wafer Fabrication
Abstract:
This paper describes the application of discrete-wavelet transform (DWT)-based algorithms to compress optical emission spectral intensity data collected during wafer fabrication. The major goal is to seek computationally efficient compression algorithms that can significantly reduce the data storage requirement but also are capable of retaining enough data authenticity critical for diagnostic purposes. The potential benefits will provide a promising foundation for an integrated data collection and compression tool. The optical emission data are treated in this paper either as images for the whole spectrum or bands of time series and are treated accordingly using appropriate DWT compression approaches. We have found through representative simulation examples that using the set partitioning in hierarchical trees compression algorithm it is achievable to obtain better than 99% storage reduction for optical emission spectrum (OES) images. For OES time series we have achieved around 95% storage reduction with Daubechies and Haar wavelets. The storage reductions are achieved while maintaining sufficient authenticity to retain the dynamic nature of OES data for diagnostic purposes.
Autors: Taikang Ning;Chung Ho Huang;John Albert Jensen;Vincent Wong;Henry Chan;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 380 - 387
Publisher: IEEE
 
» Optically 3-D $mu $ -Printed Ferrule-Top Polymer Suspended-Mirror Devices
Abstract:
We present a novel optical microfabrication technology to directly print polymer suspended-mirror devices (SMDs) on the end face of fiber-optic ferrules. With an own-established optical 3-D -printing platform, three kinds of ferrule-top SMDs were rapidly fabricated by using SU-8 photoresist. Optical reflection spectra of the fabricated SMDs were measured and then analyzed by using fast Fourier transform. The application of the ferrule-top SMD as a miniature displacement sensor was experimentally demonstrated.
Autors: Mian Yao;Jushuai Wu;A. Ping Zhang;Hwa-Yaw Tam;P. K. A. Wai;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7257 - 7261
Publisher: IEEE
 
» Optically-Enabled Bloom Filter Label Forwarding Using a Silicon Photonic Switching Matrix
Abstract:
Simplified forwarding schemes relying on Bloom filter (BF)-based labels emerge as a promising approach for coping with the substantial increase in lookup table memory requirements associated with the growing number of end-hosts in DataCenters. In this paper, we present for the first time the successful implementation of a BF-label forwarding scheme over a silicon photonic switch fabric and we demonstrate its functionality with 10 Gb/s data packets that carry BF-encoded labels. The optically enabled BF-label forwarding setup utilizes a Si-based 4 × 4 electro-optic switch directly controlled by an amplifier-less and digital-to-analog-converter-less high speed Field Programmable Gate Array board. The FPGA is responsible for extracting the BF-label from the incoming packets and for carrying out the BF-based forwarding function, determining the appropriate switching state towards conveying incoming packets to the desired output. The use of BF-label forwarding allows for rapid switch reconfiguration avoiding the need for large look-up table updates as the network topology changes and devices are added, removed or simply change physical location. Successful operation for 10 Gb/s data packets has been obtained for a 1 × 4 routing layout.
Autors: N. Terzenidis;M. Moralis-Pegios;C. Vagionas;S. Pitris;E. Chatzianagnostou;P. Maniotis;D. Syrivelis;L. Tassiulas;A. Miliou;N. Pleros;K. Vyrsokinos;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4758 - 4765
Publisher: IEEE
 
» Optimal Allocation of Dynamic Var Sources Using the Voronoi Diagram Method Integrating Linear Programing
Abstract:
Dynamic reactive power (var) sources can effectively mitigate fault-induced delayed voltage recovery (FIDVR) issues. This paper optimizes the sizes of dynamic var sources at given locations against FIDVR issues under severe contingencies. First, the geometric characteristics about the non-convex solution space of this problem are studied. Accordingly, a Voronoi diagram approach integrating linear programming (LP) is proposed, which disperses a number of sample points of potential solutions in the searching space to construct a Voronoi diagram blending the local cost functions over the entire space by Barycentric interpolation in Voronoi regions. New sample points are then recursively added, including the tentative optimal point using LP, the most depopulated area point ensuring global fidelity, and the connecting point, until the stopping criterion is met. The new approach is demonstrated in detail on the WSCC 9-bus system. A case study on the NPCC 140-bus system also validates that the proposed approach can effectively estimate the boundary and the geometry of the feasible solution region in the searching space and find the optimal solution.
Autors: Weihong Huang;Kai Sun;Junjian Qi;Jiaxin Ning;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4644 - 4655
Publisher: IEEE
 
» Optimal Angle Combination for Improving Electromagnetic Torque in Induction Motor With Double-Skewed Rotor
Abstract:
Double-skewed rotor is of great benefit to decrease harmonic magnetic fields in induction motors. But the fundamental magnetic field is damaged as well as the electromagnetic torque, like the case of normal skewed rotor. The effect of skew angle and stagger angle on the fundamental torque is studied in this paper. With the multi-slice theory, the double-skewing factor is proposed to determine the range of angle combination. Then, the range is shortened by the deduced torque coefficient with virtual displacement method. Compared with the general recommendation, the final angle combination is optimal and widely suitable for the double-skewed rotor. A higher pullout electromagnetic torque will be attained under this condition. With the finite elements-method, the validity of analysis model can be verified by the comparison of two kinds of motors.
Autors: Wei Xu;Xiaohua Bao;Chong Di;Lang Wang;Yuanyang Chen;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Optimal Bit Allocation for CTU Level Rate Control in HEVC
Abstract:
For High Efficiency Video Coding (HEVC), the R– scheme is the latest rate control (RC) scheme, which investigates the relationships among allocated bits, the slope of rate-distortion (R-D) curve , and quantization parameter. However, we argue that bit allocation in the existing R– scheme is not optimal. In this paper, we therefore propose an optimal bit allocation (OBA) scheme for coding tree unit level RC in HEVC. Specifically, to achieve the OBA, we first develop an optimization formulation with a novel R-D estimation, instead of the existing R– estimation. Unfortunately, it is intractable to obtain a closed-form solution to the optimization formulation. We thus propose a recursive Taylor expansion (RTE) method to iteratively solve the formulation. As a result, an approximate closed-form solution can be obtained, thus achieving OBA and bit reallocation. Both theoretical and numerical analyses show the fast convergence speed and little computational time of the proposed RTE method. Therefore, our OBA scheme can be achieved at little encoding complexity cost. Finally, the experimental results validate the effectiveness of our scheme in three aspects: R-D performance, RC accuracy, and robustness over dynamic scene changes.
Autors: Shengxi Li;Mai Xu;Zulin Wang;Xiaoyan Sun;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Nov 2017, volume: 27, issue:11, pages: 2409 - 2424
Publisher: IEEE
 
» Optimal Design of an Inset PM Motor With Assisted Barriers and Magnet Shifting for Improvement of Torque Characteristics
Abstract:
This paper presents an optimal design of an inset permanent magnet (PM) motor for improved torque characteristics. The key of the design is to introduce a bidirectional way of magnet shifting, along with assisted air barriers, into an inset PM motor, where magnets are shifted clockwise or anti-clockwise as needed. The introduced bidirectional shifting way lowers the requirement for shifting space between poles and also can reduce undesirable radial force to decrease vibration and noise. Moreover, the proposed inset PM motor can guarantee the torque density with great reduction of on-load torque ripple because the assisted air barriers can not only enhance the utilization of reluctance torque but also will not introduce any other torque harmonic and even can reduce torque ripple further. Also, the analytical expressions of torques are established and the appropriate angles of magnets shifting and assisted air barriers are, respectively, chosen to obtain low torque ripple and optimal torque density. Finally, these theoretical analyses are verified by the finite-element method.
Autors: Xinxin Du;Guohai Liu;Qian Chen;Gaohong Xu;Meimei Xu;Xun Fan;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Optimal Design of Electromagnetic Energy Harvester Using Analytic Equations
Abstract:
When electromagnetic (EM) energy harvesters are designed, it is common to use finite-element analysis to investigate or verify the input–output relationships. However, it requires significant computational resources if the system is nonlinear or if it is necessary to find the time-domain behavior of the harvester. If analytic or semi-analytic equations describing the field distribution are available, it would be useful for design optimization where numerous design variations must be evaluated and compared. In this paper, the field distribution around an array of permanent magnets is obtained using the method of equivalent current sheets and the method of image sources. Then, the interaction between the magnetic force and the induced voltage is modeled as nonlinear electrical damping in contrast to a damping constant which the existing literature commonly employs. The nonlinear system model is validated against the test results obtained from a prototype EM harvester. Finally, a design optimization is performed using the proposed model, resulting in an increase in the output power by 18% from the initial design.
Autors: Hyeonseok Lee;Myounggyu D. Noh;Young-Woo Park;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Optimal Design of Wound Field Synchronous Reluctance Machines to Improve Torque by Increasing the Saliency Ratio
Abstract:
This paper proposes an optimal design for a salient pole wound field synchronous machine (WFSM) with a single flux barrier to improve torque performance and obtain a wide operating range, simultaneously. The proposed WFSM motor can effectively decrease -axis inductance to improve the saliency ratio ( and increase the reluctance torque. To maximize the saliency ratio and improve the torque characteristics, the single flux barrier is optimized, considering the magnetic saturation that uses Kriging method based on Latin hypercube sampling and a genetic algorithm. The 2-D finite element analysis results by the aid of JMAG-Designer shows that the saliency ratio , the reluctance torque, and the total torque of the optimal model are increased by 9.27%, 20.45%, and 6.17%, respectively, compared with those of the basic model. Finally, the performance of the optimal motor is verified through an experimental test, which indicates good agreement with the simulation results.
Autors: Wenping Chai;Wenliang Zhao;Byung-il Kwon;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Optimal Differentiator Filter Banks for PMUs and Their Feasibility Limits
Abstract:
In this paper, we present a very general design approach for optimal linear-phase differentiator filter banks for phasor measurement units based on convex semi-infinite optimization. A detailed presentation of the formulation of both the cost functions and constraints is included for the positive-sequence phasor estimation problem. The design method is extremely powerful and flexible as it allows to control precisely the behavior of the system in terms of the total vector error (TVE), frequency error (FE), and rate of change of frequency error (RFE) metrics for several different scenarios. This feature is extremely useful for tailored designs of these filters for different applications. We also determine numerically the uniform feasibility limits of the system as a function of the filter lengths and, in particular, study the required filter lengths for compliance with the IEEE Standards C37.118.1-2011 and C37.118.1a-2014. It is found that all requirements can be achieved with a significant margin with the exception of the M class FE constraint for interharmonic components, an issue which is also reported in other works and briefly discussed here. Finally, an interesting comparison with the Taylor-Fourier filters is made to illustrate the advantages of our approach.
Autors: Francisco Messina;Leonardo Rey Vega;Pablo Marchi;Cecilia G. Galarza;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2948 - 2956
Publisher: IEEE
 
» Optimal DoF Region of the $K$ -User MISO BC With Partial CSIT
Abstract:
We consider the -user multiple-input-single-output broadcast channel, where the transmitter, equipped with antennas, serves users, with . The transmitter has access to a partial channel state information of the users. This is modeled by letting the variance of the channel state information at the transmitter error of user scale as ) for the signal-to-noise ratio and some constant . In this letter, we derive the optimal degrees-of-freedom region in such setting, and we show that rate-splitting is the key scheme to achieve such a region.
Autors: Enrico Piovano;Bruno Clerckx;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2368 - 2371
Publisher: IEEE
 
» Optimal Estimation With Missing Observations via Balanced Time-Symmetric Stochastic Models
Abstract:
We consider data fusion for the purpose of smoothing and interpolation based on observation records with missing data. Stochastic processes are generated by linear stochastic models. The paper begins by drawing a connection between time reversal in stochastic systems and all-pass extensions. A particular normalization (choice of basis) between the two time-directions allows the two to share the same orthonormalized state process and simplifies the mathematics of data fusion. In this framework, we derive symmetric and balanced Mayne–Fraser-like formulas that apply simultaneously to continuous-time smoothing and interpolation, providing a definitive unification of these concepts. The absence of data over subintervals requires in general a hybrid filtering approach involving both continuous-time and discrete-time filtering steps.
Autors: Tryphon T. Georgiou;Anders Lindquist;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5590 - 5603
Publisher: IEEE
 
» Optimal Finite-Length and Asymptotic Index Codes for Five or Fewer Receivers
Abstract:
Index coding models broadcast networks in which a sender sends different messages to different receivers simultaneously, where each receiver may know some of the messages a priori. The aim is to find the minimum (normalized) index codelength that the sender sends. This paper considers unicast index coding, where each receiver requests exactly one message, and each message is requested by exactly one receiver. Each unicast index-coding instances can be fully described by a directed graph and vice versa, where each vertex corresponds to one receiver. For any directed graph representing a unicast index-coding instance, we show that if a maximum acyclic induced subgraph (MAIS) is obtained by removing two or fewer vertices from the graph, then the minimum index codelength equals the number of vertices in the MAIS, and linear codes are optimal for the corresponding index-coding instance. Using this result, we solved all unicast index-coding instances with up to five receivers, which correspond to all graphs with up to five vertices. For 9818 non-isomorphic graphs among all graphs up to five vertices, we obtained the minimum index codelength for all message alphabet sizes; for the remaining 28 graphs, we obtained the minimum index codelength if the message alphabet size is for any positive integer . This work complements the result by Arbabjolfaei et al. (ISIT 2013), who solved all unicast index-coding instances with up to five receivers in the asymptotic regime, where the message alphabet size tends to infinity.
Autors: Lawrence Ong;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7116 - 7130
Publisher: IEEE
 
» Optimal Illumination and Color Consistency for Optical Remote-Sensing Image Mosaicking
Abstract:
Illumination and color consistency are very important for optical remote-sensing image mosaicking. In this letter, we propose a simple but effective technique that simultaneously performs image illumination and color correction for multiview images. In this framework, we first present an uneven illumination removal algorithm based on bright channel prior, which guarantees the illumination consistency inside a single image. We then adapt a pairwise color-correction method to coarsely align the color tone between source and reference images. In this stage, we give a new single-image quality metric which combines brightness deviation, color cast, and entropy together for automatic reference-image selection. Finally, we perform a least-squares adjustment (LSA) procedure to obtain optimal illumination and color consistency among multiview images. In detail, we first perform a pairwise image matching by using SIFT algorithm; once sparse local patch correspondences obtained, the illumination and color relationship between images can be established based on a global gamma correction model; the illumination and color errors can then be minimized by LSA. Extensive experiments on both challenging synthetic and real optical remote-sensing image data sets show that it significantly outperforms the compared state-of-the-art approaches. All the source code and data sets used in this letter are made public.1

https://sites.google.com/site/jiayuanli2016whu/home

Autors: Jiayuan Li;Qingwu Hu;Mingyao Ai;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1943 - 1947
Publisher: IEEE
 
» Optimal Offering and Operating Strategy for a Large Wind-Storage System as a Price Maker
Abstract:
Wind farms and energy storage systems are playing increasingly more important roles in power systems, which makes their offering nonnegligible in some markets. From the perspective of wind farm-energy storage systems (WF-ESS), this paper proposes an integrated strategy of day-ahead offering and real-time operation policies to maximize their overall profit. As participants with large capacity in electricity markets can influence cleared prices by strategic offering, a large scaled WF-ESS is assumed to be a price maker in day-ahead markets. Correspondingly, the strategy considers influence of offering quantity on cleared day-ahead prices, and adopts linear decision rules as the real-time control strategy. These allow enhancing overall profits from both day-ahead and balancing markets. The integrated price-maker strategy is formulated as a stochastic programming problem, where uncertainty of wind power generation and balancing prices are taken into account in the form of scenario sets, permitting to reformulate the optimization problem as a linear program. Case studies validate the effectiveness of the proposed strategy by highlighting and quantifying benefits comparing with the price-taker strategy, and also show the profit enhancement brought to the distributed resources.
Autors: Huajie Ding;Pierre Pinson;Zechun Hu;Jianhui Wang;Yonghua Song;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4904 - 4913
Publisher: IEEE
 
» Optimal Positioning Coordination for Multiple Linear Switched Reluctance Machines
Abstract:
This paper proposes a coordinated positioning control network for three direct drive, linear switched reluctance machines. To obtain the optimized network control parameters, the distributed linear quadratic regulator is applied. Different communication topologies are studied for both the dynamic tracking and the coordination performance of the network. Experimental results demonstrate that an absolute static tracking precision of can be achieved from the “cycle” communication topology and an absolute static coordination precision of can be obtained from the “path” communication topology.
Autors: J. F. Pan;Li Qiu;J. Zhu;Eric Cheng;Bo Zhang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» Optimal Rotor Design of an 150 kW-Class IPMSM by the 3-D Voltage–Inductance-Map Analysis Method
Abstract:
A method is presented to determine the detailed design of a 150 kW-class interior permanent-magnet synchronous motor. The basic designs of stator and rotor were determined, after dividing the designed models into the best and worst cases on the basis of the rotor-shaped parameters. First, the three-bridge basic model satisfying the structural (mechanical) safety factor of the rotor is proposed. The three-bridge basic model does not meet the required torque at rated and maximum speed compared to the no-bridge model. Therefore, it is necessary to perform the design analysis through the selection of various design parameters. However, it is hard and takes alot of time to perform an analysis with numerous shape parameters. Therefore, design parameters with the greatest effect on torque and induced voltage are found using the sensitivity analysis. And the 3-D voltage–inductance map parameters were analyzed. Then, the design of the final model was predicted. On the basis of this prediction, the final model was extracted with a trend analysis. Finally, the final model was validated with experiments.
Autors: Jun-Young Kim;Dong-Woo Kang;Tae-Chul Jeong;Dong-Hoon Jeong;Ju Lee;Sung-Gu Lee;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Optimal Scheduling for Interference Mitigation by Range Information
Abstract:
The multiple access scheduling decides how the channel is shared among the nodes in the network. Typically scheduling algorithms aims at increasing the channel utilization and thereby throughput of the network. This paper describes several algorithms for generating an optimal schedule in terms of channel utilization for multiple access by utilizing range information in a fully connected network. We also provide detailed analysis for the proposed algorithms performance in terms of their complexity, convergence, and effect of non-idealities in the network. The performance of the proposed schemes are compared with non-aided methods to quantify the benefits of using the range information in the communication. The proposed methods have several favorable properties for the scalable systems. We show that the proposed techniques yields better channel utilization and throughput as the number of nodes in the network increases. We provide simulation results in support of this claim. The proposed methods indicate that the throughput can be increased on average by times for typical network configurations.
Autors: Vijaya Yajnanarayana;Klas E. G. Magnusson;Rasmus Brandt;Satyam Dwivedi;Peter Händel;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Nov 2017, volume: 16, issue:11, pages: 3167 - 3181
Publisher: IEEE
 
» Optimal Structure Design of Permanent Magnet Motors Based on a General Pattern of Rotor Topologies
Abstract:
For the purpose of saving energy resources, it is extremely expected to develop highly efficient electric motors. Different types of permanent magnet (PM) arrangement can significantly affect the performance of the motors. Conventionally, the arrangement of the PMs is determined by designer’s experience. This paper focuses on the optimal design of PM arrangement in PM synchronous motors (PMSMs). We present a general pattern of the PM arrangement in PMSM. By varying the parameters of the general pattern, it can produce different types of PM arrangement in the rotor. The employed approach combines the global optimization method with the finite-element method for solving the optimization of the PM structures. Based on the proposed general pattern and optimization methods, the best PM arrangement in the motor can be automatically determined. In order to reduce computing loading, this paper employs the response surface models for reducing the computing time of objective functions. In the end, numerical tests are designed to showcase the effectiveness of the proposed method.
Autors: Xiaoyu Liu;W. N. Fu;Shuangxia Niu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Optimal Transmit Beamforming for Secure SWIPT in a Two-Tier HetNet
Abstract:
This letter investigates the artificial noise aided beamforming design for secure simultaneous wireless information and power transfer in a two-tier downlink heterogeneous network (HetNet), where one femtocell underlays one macrocell in co-channel deployment. Each energy receiver in femtocell can be considered as a potential eavesdropper for messages intended for information receiver (IR). Our objective is to maximize the secrecy rate at IR subject to the signal-to-interference-plus noise ratio requirements of macro users, transmit power constraint and energy harvesting constraint. Due to the non-convexity of the formulated problem, it cannot be solved directly. Thus, we propose a novel reformulation by using first-order Taylor expansion and successive convex approximation (SCA) techniques. Furthermore, an SCA-based algorithm with low complexity is proposed to arrive at provably convergent solution. Finally, numerical results evaluate the performance of the proposed algorithm.
Autors: Bin Li;Zesong Fei;Zheng Chu;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2476 - 2479
Publisher: IEEE
 
» Optimally Controlled Pure ALOHA Systems for Wireless Sensor Networks
Abstract:
Pure ALOHA would be one of the candidate techniques to realize low-power wide-area networks and various applications of Internet of Things with a huge number of low-cost end-devices (EDs) and sensors. No strict time-synchronization of pure ALOHA systems may reduce the hardware cost of sensors and system significantly. As such, this letter characterizes the performance of pure ALOHA systems in terms of throughput, access delay, and stability, and further proposes a particle-filter-based control algorithm for retransmission intervals of EDs to achieve near-optimal throughput performance.
Autors: Jun-Bae Seo;Hu Jin;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2460 - 2463
Publisher: IEEE
 
» Optimization Design of PMSM With Hybrid-Type Permanent Magnet Considering Irreversible Demagnetization
Abstract:
This paper proposes optimization design of permanent-magnet synchronous motor (PMSM) using hybrid-type permanent magnet (PM) considering irreversible demagnetization. Here, the hybrid-type PM is defined as using both of neodymium PM (Nd-PM) and ferrite PM (Fe-PM) in a rotor. First, irreversible demagnetization of Fe-PM occurring by reversed magnetic field of Nd-PM is analyzed by using a finite-element method, when a rotor is inside or without a stator in order to improve reliability of PMSM using hybrid-type PM. Second, the optimized design considering demagnetization phenomenon is suggested for analyzing exactly output characteristics of the motor using hybrid-type PM. Finally, the prototypes based on proposed design are developed for evaluating the performance and demagnetization phenomenon through experiment.
Autors: Chae-Lim Jeong;Jin Hur;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Optimization of Vibration and Noise Characteristics of Skewed Permanent Brushless Direct Current Motor
Abstract:
In this paper, we analyze the vibration and noise characteristics of the basic and skewed models of permanent brushless direct current (BLDC) motor. The electromagnetic characteristics of the basic model are analyzed by the finite-element method. We analyzed the electromagnetic characteristics for skew angles from 15° to 25°. The skew angle was selected based on the analytical results of the electromagnetic characteristics. We analyzed the characteristics of radial force density for the basic model and the skewed model. The vibration and noise characteristics were analyzed through the mechanical harmonic analysis of the radial force and tangential force generated in the motor. We developed the basic and skewed models, and performed vibration and noise tests. The validity of this analysis is verified by comparing the simulation results with the actual test results of the model. Finally, for the optimal design of the BLDC motor considering vibration, the design variables such as teeth shoe length, yoke thickness, and teeth thickness were used. Based on the results of vibration analysis, the final model is derived and its performance is described.
Autors: Chang-Min Lee;Hyun-Soo Seol;Jae-yong Lee;Seung-Hwan Lee;Dong-Woo Kang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Optimized Manipulation of the Network Characteristic Modes for Wideband Small Antenna Matching
Abstract:
Multiport antenna systems can be regarded as -port networks, which can be analyzed using the theory of network characteristic modes (NCMs). Due to the profound physical insights provided by an NCM, a desired antenna performance can be achieved by properly manipulating the modes through reactive loading at specified ports. This paper presents a new matching technique for an -port internally loaded small antenna. By combining the NCM with the differential evolution algorithm, optimal reactive load values can be calculated. These loads can manipulate the NCMs to match the antenna in a desired bandwidth. Unlike other matching techniques based on the NCM, the desired bandwidth is achieved through internal reactive loading without the need for an input matching network. Two examples of electrically small monopole antennas are studies. In both examples, we study the possibility to match the antennas in the GSM 900 band, and we further investigate the possibility to achieve wider bandwidths by varying the number of ports and the loading topologies based on the interpretation of the characteristic modes. The loaded antennas are wideband with a relatively stable radiation pattern and an efficiency higher than 90%. To confirm the theoretical results, a prototype is fabricated and measured.
Autors: Hussein Jaafar;Sylvain Collardey;Ala Sharaiha;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 5757 - 5767
Publisher: IEEE
 
» Optimized Measurement Allocation for Power Distribution Systems Using Mixed Integer SDP
Abstract:
This paper presents a method for placement of metering systems in distribution grids taking into account the aspects of observability and state estimation accuracy. The measurement placement problem is conceptualized as the optimized allocation of a prespecified number of measurements in order to minimize the error variances of the state estimates either for observable or nonobservable networks. The proposed approach exploits the M-optimal experimental design technique to formulate the problem as a mixed integer semidefinite programming model. We demonstrate the efficacy of the proposed approach in terms of optimality and convergence speed through simulations on a 95-bus distribution grid.
Autors: Themistoklis C. Xygkis;George N. Korres;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2967 - 2976
Publisher: IEEE
 
» Optimized State Space Grids for Abstractions
Abstract:
The practical impact of abstraction-based controller synthesis methods is currently limited by the immense computational effort for obtaining abstractions. In this note we focus on a recently proposed method to compute abstractions whose state space is a cover of the state space of the plant by congruent hyper-intervals. The problem of how to choose the size of the hyper-intervals so as to obtain computable and useful abstractions is unsolved. This note provides a twofold contribution towards a solution. Firstly, we present a functional to predict the computational effort for the abstraction to be computed. Secondly, we propose a method for choosing the aspect ratio of the hyper-intervals when their volume is fixed. More precisely, we propose to choose the aspect ratio so as to minimize a predicted number of transitions of the abstraction to be computed, in order to reduce the computational effort. To this end, we derive a functional to predict the number of transitions in dependence of the aspect ratio. The functional is to be minimized subject to suitable constraints. We characterize the unique solvability of the respective optimization problem and prove that it transforms, under appropriate assumptions, into an equivalent convex problem with strictly convex objective. The latter problem can then be globally solved using standard numerical methods. We demonstrate our approach on an example.
Autors: Alexander Weber;Matthias Rungger;Gunther Reissig;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5816 - 5821
Publisher: IEEE
 
» Optimizing Spectrum Sensing Time With Adaptive Sensing Interval for Energy-Efficient CRSNs
Abstract:
The cognitive radio (CR) technology allows secondary users (SUs) to occupy the licensed bands opportunistically without causing interferences to primary users (PUs). SUs perform spectrum sensing to detect whether PUs are busy or idle. Therefore, spectrum sensing directly affects the performance of the PU protection and the secondary throughput. The sensing time is a critical parameter for spectrum sensing performance, and the optimum sensing time is a tradeoff between the spectrum sensing performance and the secondary throughput. In this paper, a novel spectrum sensing scheme is proposed to maximize both sensing accuracy and network energy efficiency. In order to provide a better protection for the PU, another spectrum sensing is adaptively performed according to the first sensing result. In other words, SU will perform spectrum sensing again to confirm that the PU is indeed idle when the first sensing result indicates the PU is idle. Due to the energy constraint in CR sensor networks, this adaptive sensing interval can also be adjusted according to the varying activity of the PU to maximize the network energy efficiency. Finally, our simulation study validates that the proposed scheme improves both the spectrum sensing performance and the energy efficiency compared with other existing methods.
Autors: Fanhua Kong;Jinsung Cho;Ben Lee;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7578 - 7588
Publisher: IEEE
 
» Origami: A 803-GOp/s/W Convolutional Network Accelerator
Abstract:
An ever-increasing number of computer vision and image/video processing challenges are being approached using deep convolutional neural networks, obtaining state-of-the-art results in object recognition and detection, semantic segmentation, action recognition, optical flow, and super resolution. Hardware acceleration of these algorithms is essential to adopt these improvements in embedded and mobile computer vision systems. We present a new architecture, design, and implementation, as well as the first reported silicon measurements of such an accelerator, outperforming previous work in terms of power, area, and I/O efficiency. The manufactured device provides up to 196 GOp/s on 3.09 of silicon in UMC 65-nm technology and can achieve a power efficiency of 803 GOp/s/W. The massively reduced bandwidth requirements make it the first architecture scalable to TOp/s performance.
Autors: Lukas Cavigelli;Luca Benini;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Nov 2017, volume: 27, issue:11, pages: 2461 - 2475
Publisher: IEEE
 
» Orthogonal Magnetic Field Analysis of a Double-Stator Linear-Rotary Permanent Magnet Motor With Orthogonally Arrayed Permanent Magnets
Abstract:
In this paper, a double-stator linear-rotary permanent magnet motor (DSLRPMM) for linear and/or rotary movement is presented. Since the two types of permanent magnets are orthogonally arrayed on the inner and outer surfaces of the mover core, respectively, the influences of the orthogonal magnetic field (OMF) on the motor electromagnetic characteristics cannot be ignored. Based on the 3-D finite-element method (FEM), the OMF in the motor and the iron core magnetization characteristics are investigated, and a test device is constructed to verify the results obtained by the theoretical analysis and 3-D finite-element analysis (FEA). On the basis of the measured data, the 2-D FEM is employed to analyze the electromagnetic characteristics of the DSLRPMM, including flux density, flux linkage, back-electromotive force, detent force, and cogging torque. The results are compared with that obtained by the 3-D FEA, and they are in agreement. Moreover, a prototype is built and tested. The experimental results verify the correctness of the predictions.
Autors: Lei Xu;Mingyao Lin;Xinghe Fu;Xiaoyong Zhu;Chao Zhang;Wenye Wu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Outage Performance for Cooperative NOMA Transmission with an AF Relay
Abstract:
This letter studies the outage performance of cooperative non-orthogonal multiple access (NOMA) network by adopting an amplify-and-forward relay. An accurate approximation for the outage probability is derived and then the asymptotic behaviors are investigated. It is revealed that cooperative NOMA achieves the same diversity order and the superior coding gain compared to cooperative orthogonal multiple access. It is also shown that the outage performance improves when the distance between the relay and indirect link user decreases, assuming the smaller transmit power of relay than the base station.
Autors: Xuesong Liang;Yongpeng Wu;Derrick Wing Kwan Ng;Yiping Zuo;Shi Jin;Hongbo Zhu;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2428 - 2431
Publisher: IEEE
 
» Overview of Passive Optical Multispectral and Hyperspectral Image Simulation Techniques
Abstract:
The simulation of optical images can play key roles in the development of new instruments, the quantitative evaluation of algorithms and in the training of both image analysis software and human analysts. Methods for image simulation include surrogate data collections, operations on empirical imagery, statistical generation techniques, and full physical modeling approaches. Each method offers advantages or disadvantages in terms of time, cost, and realism. Current state of the art suggests three-dimensional radiative transfer models capture most of the significant characteristics of real imagery and find valuable use in system development and evaluation programs. Emerging computational power available from multithreading, graphical processing units, and techniques from deep learning will continue to enable even more realistic simulations in the near future.
Autors: Sanghui Han;John P. Kerekes;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 4794 - 4804
Publisher: IEEE
 
» Pairing and Power Allocation for Downlink Nonorthogonal Multiple Access Systems
Abstract:
In this paper, a greedy-search-based user pairing and selection method as well as an optimal power allocation approach is proposed to maximize the weighted sum rate of a downlink nonorthogonal multiple access (NOMA) system. The NOMA system consists of one base station and multiple users. By exploiting superposition coding and successive interference cancellation techniques at the receiver, multiple users can be multiplexed into transmit power domain, and then nonorthogonally scheduled for transmission on the same spectrum resources. The proposed greedy-search-based user pairing method has low computational complexity and the power allocation method is shown to be equivalent to a weighted minimum mean square error based problem, which is solved using an iterative procedure. The subproblem in each step of the iteration has a closed-form solution. Also, the convergence of the iteration is proved. Simulation results show that the proposed method can significantly improve the sum rate of the system over the other methods.
Autors: Lanjie Shi;Bo Li;Haihua Chen;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10084 - 10091
Publisher: IEEE
 
» Pairwise Stochastic Bounded Confidence Opinion Dynamics: Heavy Tails and Stability
Abstract:
Unlike traditional graph-based linear dynamics, where agents exchange opinions with their neighbors in a static social graph regardless of their differences in opinions, the bounded confidence opinion dynamics models exchange between agents with similar opinions. We generalize the bounded confidence opinion dynamics model by incorporating pairwise stochastic interactions, probabilistic influencing based on opinion differences and the self or endogenous evolutions of the agent opinions, which are represented by random processes. The opinion exchanges resulting from influencing have pairwise contraction effects, whereas endogenous motions have an expansive effect, for instance, of a diffusive nature. We analytically characterize the conditions under which this stochastic dynamics is stable in an appropriate sense. In the diffusive case, the presence of heavy tailed influence functions with a Pareto exponent of 2 is critical for stability (for a pair of agents an influence function maps opinion differences to probabilities of influence). Moreover, this model sheds light on dynamics that combine aspects of graph-based and bounded confidence dynamics.
Autors: François Baccelli;Avhishek Chatterjee;Sriram Vishwanath;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5678 - 5693
Publisher: IEEE
 
» Parameter Calculation and Analysis of a Novel Wind Power Generator
Abstract:
Compared with the commonly used generators, the brushless doubly fed generator (BDFG) has a commercial potential for wind power generation due to its inherent characteristics. In this paper, a novel BDFG with hybrid rotor is proposed and its structural features and operation principle are presented. Meanwhile, the performance of the proposed BDFG is analyzed in comparison with the BDFG using a radial laminated magnetic barrier rotor. Furthermore, due to the complexity of the magnetic field and the particularity of the structure, the calculation and analysis of the parameters, especially the inductance, are extremely important for the performance analysis of the proposed BDFG. Therefore, an inductance calculation method based on modified winding function is investigated. For accurate inductance calculation, the effects of magnetic layers and cage bars on the air-gap permeance of the proposed hybrid rotor are both considered. Tests are performed on a 25 kW prototype machine to verify the performance of the proposed BDFG. The experimental results show the correctness and feasibility of the proposed inductance calculation method.
Autors: Siyang Yu;Fengge Zhang;Hao Wang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 7
Publisher: IEEE
 
» Parametric Optimum Design of a Graphene-Based Thermionic Energy Converter
Abstract:
A new model of the thermionic energy converter (TEC) configured with the graphene-based cathode is proposed, which includes the thermal radiation between the cathode and the anode electrodes and the heat losses from the anode to the environment. Analytic expressions for the power output density and efficiency of the TEC are derived. The performance characteristics of the TEC are analyzed by numerical calculations. It is found that the maximum efficiency and power density can, respectively, reach 30% and when the TEC is operated between the two heat reservoirs at temperatures 1500 and 300 K. In addition, the optimum regions of the efficiency, power density, voltage output, electric current, and anode temperature are determined. The maximum efficiency and power density of the graphene-based TEC operated at different temperatures are calculated and compared with those of the metal-based TEC. It shows that the graphene-based TEC operated at 1200–1800 K displays the better performance than the metal-based TEC. The results obtained here may provide guidance for the appropriate selection of electrode materials and optimum design of practical TEC devices.
Autors: Xin Zhang;Yuzhuo Pan;Jincan Chen;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4594 - 4598
Publisher: IEEE
 
» Partial Overlapped Time-Shifted Pilots for Massive MIMO Systems
Abstract:
This letter proposes a partial-time-shifted pilot scheme to find a better tradeoff between the user accommodation and orthogonality of pilots for the massive multiple-input multiple-output system. To this end, the pilot symbols rather than the pilot sequences are applied. In addition, the neighboring cells are allowed to transmit the pilot signals using the overlapped symbol periods. Despite the stronger interference, the larger user accommodation as well as the near-far effect incurred by using the pilot symbols can contribute to the higher sum transmission rates for both the uplink and downlink cases.
Autors: Wenson Chang;Yun-Kuei Hua;Shu-Fong Liao;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2480 - 2483
Publisher: IEEE
 
» Particle Adsorption Onto Si-Based Wafers in Ultrapure Water; Its Mechanism and Effect of Carbon Dioxide
Abstract:
Ultrapure water contains several kinds of contaminants. In particular, we paid much attention to particles and investigated particles adsorption onto Si-based wafers. We succeed in making a model through two experiments. One is to study an impact of spin cleaning parameters on particle adsorption, and the other is to study that of such impurities as urea, hydrogen peroxide, carbon dioxide, and so on. The former test succeeded in quantitatively estimating the magnitude of each degree of influence to some extent assuming that there are roughly two steps of attaching particles to the wafer, namely adsorption equilibrium during rinsing and residuals during drying. The latter is to confirm that substances that are likely to be mixed in ultrapure water do not affect particle adsorption in the future manufacturing process. We concluded that we need to pay attention to carbon dioxide especially in this system.
Autors: Koji Nakata;Takeo Fukui;Tatsuo Nagai;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 371 - 376
Publisher: IEEE
 
» Passively Track WiFi Users With an Enhanced Particle Filter Using Power-Based Ranging
Abstract:
Passive positioning systems produce user location information for third-party providers of positioning services. In this paper, we provide a passive tracking system for WiFi signals with an enhanced range-only particle filter using fine-grained power. Our proposed particle filter, WVT-bootstrap particle filter, provides improved observation likelihood and is equipped with a single coordinated turn model to address the challenges in passive positioning. The anchor nodes for WiFi signal sniffing use software defined radio techniques to extract channel state information for multipath mitigation and a non-linear regression method is used for the path-loss model. Our tracking system produces measured positioning errors that, in the 80th percentile, are equal to or less than 2 m; this represents a 33% improvement over the traditional bootstrap particle filter. Additionally, it requires (0.12 s for 1000 particles) only half of the computation efforts as a multi-model particle filter.
Autors: Zan Li;Torsten Braun;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7305 - 7318
Publisher: IEEE
 
» Past forward: world's most famous teapot [Past forward]
Abstract:
Do you recognize this teapot? Tea boffins might recognize it as a Melitta product. Computer graphics people, though, know this as the "Utah teapot." In the mid-1970s, Martin Newell created an impressive 3D model of the teapot for his Ph.D. work at the University of Utah. Other researchers adopted the iconic teapot to develop new graphics hardware and software. It also made cameo appearances in Toy Story, Monsters, Inc., and “The Simpsons,” eventually earning it the moniker of "World' Most Famous Teapot."
Autors: David C. Brock;
Appeared in: IEEE Spectrum
Publication date: Nov 2017, volume: 54, issue:11, pages: 68 - 68
Publisher: IEEE
 
» Patching the internet of things
Abstract:
ON 21 OCTOBER OF LAST YEAR, a variety of major websites—including those of Twitter, PayPal, Spotify, Netflix, The New York Times, and The Wall Street Journal—stopped working. The cause was a distributed denial-of-service attack, not on these websites themselves but on the provider they and many others used to support the Domain Name System, or DNS, which translates the name of the site into its numerical address on the Internet. The DNS provider in this case was a company called Dyn, whose servers were barraged by so many fake requests for DNS lookups that they couldn’t answer the real ones.
Autors: Sandip Ray;Abhishek Basak;Swarup Bhunia;
Appeared in: IEEE Spectrum
Publication date: Nov 2017, volume: 54, issue:11, pages: 30 - 35
Publisher: IEEE
 

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