Electrical and Electronics Engineering publications abstract of: 07-2017 sorted by title, page: 4

» Characterization of Microring Filters for Differential Group Delay Applications
Abstract:
The longitudinal offset technique permits to improve the accuracy of the coupling coefficients of integrated directional couplers and provides designs that can be easily implemented with current fabrication tolerances. In this paper, we address the additional degree of freedom offered by this technology in order to tailor the differential group delay in coupled-resonator optical filters. We present the characterization of several devices exploiting this feature and we discuss their potential applications.
Autors: David Doménech;Pedro Chamorro-Posada;Francisco J. Fraile-Pelaez;Maria Jose Erro;Santiago Tainta Ausejo;Miguel A. Muriel;Rocio Baños;Jens Bolten;Herbert Kleinjans;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2017, volume: 35, issue:14, pages: 2943 - 2947
Publisher: IEEE
 
» Characterization of Surface Radar Cross Sections at W-Band at Moderate Incidence Angles
Abstract:
This paper presents the results of a recent flight campaign conducted over the Great Lakes region and reports the first observations of the W-band normalized backscattered cross section () for V and H polarization and the linear depolarization ratios (LDRs) from different types of surfaces at moderate incidence angles (<70°). For sea surfaces, while the observed behaves as previously reported at small incidence angles, it features a marked decrease with increasing incidence angles between 20° and 50°. There is a strong dependence of normalized backscattered cross sections both on the wind speed and on the wind direction, with larger values found in the presence of higher wind speeds and when the radar antenna is looking upwind. This is in line with theoretical models (though models tend to overpredict the range of variability at a given incidence angle) and with observations at lower frequencies. The LDRs are steadily increasing from values certainly lower than −30 dB, at vertical incidence, to the values of about −10 dB, at the incidence angles of about 60°–70°, with a good matching between observations and theoretical predictions. On the other hand, land surface backscattering properties are not characterized by a strong angular dependence: and LDR values typically range between −20 and 0 dB and between −15 and −5 dB, respectively. This paper is relevant for spaceborne concepts of W-band radars, which envisage moderate incidence angles to achieve a broad swath needed for global cov- rage.
Autors: Alessandro Battaglia;Mengistu Wolde;Leo Pio D’Adderio;Cuong Nguyen;Franco Fois;Anthony Illingworth;Rolv Midthassel;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jul 2017, volume: 55, issue:7, pages: 3846 - 3859
Publisher: IEEE
 
» Characterization of Temperature-Dependent Refractive Indices for Nematic Liquid Crystal Employing a Microfiber-Assisted Mach–Zehnder Interferometer
Abstract:
The temperature dependence of refractive indices for nematic liquid crystal (NLC) is characterized in the near-infrared region by employing an all-fiber ultrasensitive microfiber-assisted Mach–Zehnder interferometer (MAMZI). Owing to the unique thermal-optic properties of NLC, the proposed MZI shows inverse temperature sensitivities of –7.311 and 77 nm/K right above and below the clearing temperature of liquid crystal E7, respectively. Furthermore, the temperature dependences of ordinary and extraordinary refractive indices could be acquired by performing curve fitting on the experimentally measured interference dip wavelength as functions of environmental temperature based on the four-parameter model derived from Vuks equation.
Autors: Nanjie Xie;Hao Zhang;Bo Liu;Binbin Song;Jixuan Wu;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2017, volume: 35, issue:14, pages: 2966 - 2972
Publisher: IEEE
 
» Characterization of the Timing Homogeneity in a CMOS SPAD Array Designed for Time-Gated Raman Spectroscopy
Abstract:
A characterization environment was built to verify the timing characteristics of a single photon avalanche diode (SPAD) array designed for time-gated Raman spectroscopy. The characterization was applied to a 256 × 16 SPAD array that employed an on-chip time-to-digital converter (TDC) with a 50-100-ps resolution for time resolving. The timing skew and the time window homogeneity across the array were resolved, moving the time-resolving windows over an optical pulse by picosecond-level delay steps. A typical one 160-ps skew across the array was measured. The TDC time bins had average sizes of 33-144 ps while their deviation across the array was 8-12 ps. The method is applicable to multidetector time-correlated single photon counting systems that can finely adjust the delay between the optical pulse and the reference signal.
Autors: Jouni Holma;Ilkka Nissinen;Jan Nissinen;Juha Kostamovaara;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jul 2017, volume: 66, issue:7, pages: 1837 - 1844
Publisher: IEEE
 
» Charge Trapping Mechanism Leading to Sub-60-mV/decade-Swing FETs
Abstract:
In this paper, we present a novel method to reduce the subthreshold swing (SS) of FETs below 60 mV/decade. Through modeling, we directly relate trap charge movement between the gate electrode and the gate dielectric to SS reduction. We experimentally investigate the impact of charge exchange between a Cu gate electrode and a 5-nm-thick amorphous Al2O3 gate dielectric in an InGaZnO4 thin-film transistor. Positive trap charges are generated inside the gate dielectric while the semiconductor is in accumulation. During the subsequent detrapping, the SS diminishes to a minimum value of 46 mV/decade at room temperature. Furthermore, we relate the charge trapping/detrapping effects to a negative capacitance behavior of the Cu/Al2O3 metal–insulator structure.
Autors: Alwin Daus;Christian Vogt;Niko Münzenrieder;Luisa Petti;Stefan Knobelspies;Giuseppe Cantarella;Mathieu Luisier;Giovanni A. Salvatore;Gerhard Tröster;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2017, volume: 64, issue:7, pages: 2789 - 2796
Publisher: IEEE
 
» Circuit Modeling of Waveguide Grating Nanostructures in Ultrathin Solar Cells
Abstract:
In this paper, a circuit modeling is used to investigate the effects of waveguide grating nanostructures on the performance of ultrathin solar cells. The proposed method is based on transmission line equivalent circuit (TLEC) and it is identified for both of the transverse electric and transverse magnetic polarizations. Under assumption of weak-coupling condition, this method can effectively describe the absorption inside ultrathin solar cells with the one-dimensional grating nanostructure etched into the anti-reflection coating layers. The proposed approach consists of two different circuits accounting for the background and scattering fields. The final result of the TLEC method comprises of the superposition of the background and scattering TLEC circuits.
Autors: Mohammad Reza Salehi;Mojtaba Shahraki;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jul 2017, volume: 16, issue:4, pages: 616 - 623
Publisher: IEEE
 
» Circulating Current Suppression for MMC-HVDC under Unbalanced Grid Conditions
Abstract:
Modular multilevel converter (MMC) is believed the most competitive solution for high-voltage direct current (HVDC) transmission using voltage source converters. Circulating current suppressing strategies based on proportional resonant (PR) controllers are widely used in MMC. This kind of strategies can effectively eliminate all the circulating current components in MMC-HVDC. Unfortunately, it can result in dc-line voltage ripples under unbalanced grid conditions, and thus, deteriorates system performance and stability. Moreover, its existing control model may not exactly reveal the inherent characteristic of MMC, and consequently blocks the further understanding and application. To solve these two problems, first, this paper builds a new and effective control model for this strategy. Second, based on the new model, this paper studies the relationship between circulating current reference value and submodule capacitor voltage, modulation index, and arm current to correct and improve the current understanding of this control strategy. Finally, three improved strategies based on PR controllers are proposed. These improved control strategies can eliminate both circulating current and dc-line voltage ripples, which greatly enhance the fault ride-through capability of MMC-HVDC without adding extra control cost or the number of controllers.
Autors: Jinyu Wang;Jun Liang;Chengfu Wang;Xiaoming Dong;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3250 - 3259
Publisher: IEEE
 
» City-Scale Localization for Cameras with Known Vertical Direction
Abstract:
We consider the problem of localizing a novel image in a large 3D model, given that the gravitational vector is known. In principle, this is just an instance of camera pose estimation, but the scale of the problem introduces some interesting challenges. Most importantly, it makes the correspondence problem very difficult so there will often be a significant number of outliers to handle. To tackle this problem, we use recent theoretical as well as technical advances. Many modern cameras and phones have gravitational sensors that allow us to reduce the search space. Further, there are new techniques to efficiently and reliably deal with extreme rates of outliers. We extend these methods to camera pose estimation by using accurate approximations and fast polynomial solvers. Experimental results are given demonstrating that it is possible to reliably estimate the camera pose despite cases with more than 99 percent outlier correspondences in city-scale models with several millions of 3D points.
Autors: Linus Svärm;Olof Enqvist;Fredrik Kahl;Magnus Oskarsson;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jul 2017, volume: 39, issue:7, pages: 1455 - 1461
Publisher: IEEE
 
» Clock Sequences for Increasing the Fault Coverage of Functional Test Sequences
Abstract:
A functional test sequence for a design may not be effective as a manufacturing test for a logic block in the design because it achieves a low gate-level fault coverage. This paper describes a procedure for selecting a clock sequence that increases the gate-level fault coverage of a functional test sequence when it is used for testing a subset of logic blocks. The procedure deactivates the clocks to the logic blocks in the subset when a primary input vector has a negative effect on their fault coverage. The procedure is different from earlier test generation and test compaction procedures in that it increases the fault coverage without modifying the functional test sequence. It thus preserves some of the functional characteristics and the test application process for the sequence. Experimental results for benchmark circuits are presented to demonstrate the effectiveness of the procedure.
Autors: Irith Pomeranz;
Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Publication date: Jul 2017, volume: 36, issue:7, pages: 1231 - 1235
Publisher: IEEE
 
» Closed-Loop Control of a Magnetic Particle at the Air–Liquid Interface
Abstract:
One of the greatest challenges in microrobotics is the development of robotic devices for high-speed transportation and precise positioning of microcomponents. This paper proposes to use non contact magnetic actuation in which objects are placed at the air/liquid interface and are actuated through magnetic field gradients. A physical model is developed and identified to perform closed-loop control. This approach is validated through several experiments in 1-D. Precise positioning and high-speed trajectory tracking of objects smaller than 100 are achieved. The position error of an object of 60 is less than 10% of its size and the maximum velocity reached is about . The closed-loop control has been tested on objects as small as 30 and demonstrates its ability to perform precise positioning (the position error is less than 7% of the size of the object). This approach represents a promising solution to design devices for high throughput transportation and precise positioning of micro-objects, which will lead to magnetic smart surfaces at micrometer scale.
Autors: Mohamed Dkhil;Mohamed Kharboutly;Aude Bolopion;Stéphane Régnier;Michaël Gauthier;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jul 2017, volume: 14, issue:3, pages: 1387 - 1399
Publisher: IEEE
 
» Cloud Free Line of Sight Prediction Modeling for Optical Satellite Communication Networks
Abstract:
Analytical models for the prediction of cloud-free line-of-sight (CFLOS) probability for a single optical satellite link and for multiple spatially separated optical satellite links are presented. The presence of clouds along the slant paths causes their blockage. As a result, an ON/OFF channel with the presence of clouds is assumed. The proposed model for the calculation of CFLOS considers the elevation angle of the optical satellite links, the altitude of ground stations, and the spatial variability of clouds. The methodology is based on the assumption that integrated liquid water content (ILWC) follows lognormal distribution and a well-defined relationship between ILWC and liquid water density. Moreover, joint CFLOS statistics are evaluated and CFLOS probability for simultaneously available optical links for the application of spatial multiplexing transmission techniques is estimated. The models are validated through simulated results and finally, the numerical results are devoted to optical satellite network examples with a view to achieving specific availability percentage.
Autors: Nikolaos K. Lyras;Charilaos I. Kourogiorgas;Athanasios D. Panagopoulos;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1537 - 1540
Publisher: IEEE
 
» Cluster-CMSS: A Cluster-Based Coordinated Spectrum Sensing in Geographically Dispersed Mobile Cognitive Radio Networks
Abstract:
A coordinated multiband spectrum sensing (CMSS) policy for mobile and geographically dispersed cognitive radio networks (CRNs), referred to as cluster-CMSS, is proposed. The goal is to detect the spectrum holes and to assign each secondary user (SU) a sensing channel with the maximum probability of being empty. In geographically dispersed CRNs, channel availability varies over the space, and this makes the sensing outcomes and sensing assignments location dependent. However, if the SUs are not equipped with location-finding technologies, fusing the sensing outcomes to find the optimal spectrum sensing assignments for the next sensing time becomes challenging for the base station (BS). To tackle this problem, we introduce a metric solely based on the sensing outcomes of SUs. Using this metric, along with a low-complexity clustering algorithm, enables the BS to efficiently divide the network into clusters. Further, we present an adaptive learning algorithm, to learn the dynamic behavior of channel occupancy in the primary network. The proposed learning algorithm considers SUs mobility model to determine the optimal learning window. To determine the sensing assignments, the BS performs a graph-theory-based coordinated multiband spectrum sensing within each cluster. Specifically, a weighted bipartite matching is employed. We have shown that cluster-CMSS significantly increases the spectrum opportunity discovery ratio for SUs at the cost of a slight increase in the energy consumption associated with spectrum sensing.
Autors: Behzad Shahrasbi;Nazanin Rahnavard;Azadeh Vosoughi;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 6378 - 6387
Publisher: IEEE
 
» Code Division Multiplexing Applied to FBG Sensing Networks: FBG Sensors Designed as Discrete Prolate Spheroidal Sequences (DPSS-FBG Sensors)
Abstract:
We propose and demonstrate a sensing system with fiber Bragg grating sensors designed as discrete prolate spheroidal sequences (DPSS). In this way, we can encode all of the sensing devices in the network making sure that each sensor is completely distinguishable from each other even under overlapping conditions. Since these devices are complex structures involving unique magnitude and phase response, the demodulation method should be able to recover the associated magnitude and phase response in order to identify each device in the sensing network. To do so, we use a single side band modulated optical source sweeping over the operational wavelength range of the sensors, the reflected signal from the sensors is sent to a vector network analyzer in which it is obtained the magnitude and phase ratio of the network in the microwave domain. Experimental demonstration has been carried out including the manufacturing of DPSS structures. Feasibility of the interrogation technique for devices involving magnitude and phase distinction has been validated, not only to identify encoded sensors in a measurement network but also to allow overlapping between them, which allow to increase the number of sensors allocated in the sensing network.
Autors: Andrés Triana;Daniel Pastor;Margarita Varón;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2017, volume: 35, issue:14, pages: 2880 - 2886
Publisher: IEEE
 
» Coded OFDM-IM With Transmit Diversity
Abstract:
In this paper, we propose a simple transmit diversity scheme for orthogonal frequency division multiplexing (OFDM) with index modulation (IM) in order to achieve a diversity gain for index detection, which can significantly improve the performance of OFDM-IM at the cost of the spectral efficiency. An optimal approach for active index detection is derived, which has a complexity, growing linearly with the size of OFDM symbol. A salient feature of the proposed transmit diversity scheme is that it can be easily employed in conjunction with a conventional coding scheme for data symbols. Consequently, we can implement coded OFDM-IM together with the proposed transmit diversity scheme in a straightforward manner, which can provide a good performance under a frequency-fading environment.
Autors: Jinho Choi;
Appeared in: IEEE Transactions on Communications
Publication date: Jul 2017, volume: 65, issue:7, pages: 3164 - 3171
Publisher: IEEE
 
» Cogging Torque Cancellation by Magnet Shaping in Surface-Mounted Permanent-Magnet Motors
Abstract:
This paper presents a new method for cancellation cogging torque by magnet shaping. First, the conditions to be met by the induction space wave for the total cancellation of cogging torque are analytically established. These results are then used to determine the shape of the magnets. The approach followed is inverse to that used by traditional methods, whereby, based on a predetermined shape of the magnets, the cogging torque is calculated. As a result, the proposed method enables optimum results to be obtained directly and it is generalizable to any motor configuration. The methodology has been first validated by means of finite elements and then tested experimentally on a dc motor and on an ac motor for both radial and parallel magnetization.
Autors: Vicente Simón-Sempere;Manuel Burgos-Payán;José-Ramón Cerquides-Bueno;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jul 2017, volume: 53, issue:7, pages: 1 - 7
Publisher: IEEE
 
» Cognitive Radio With Self-Power Recycling
Abstract:
In cognitive radio networks, a secondary user (SU) equipped with radio frequency (RF) energy-harvesting circuits can not only harvest the RF energy from the primary transmitter, but also recycle its self-power when transmitting. In this paper, we are concerned with the following design metrics: SU's harvested energy, SU's energy efficiency, and SU's harvesting efficiency, which is defined as the ratio of the average energy harvested by SU over its average energy consumption. We are interested in two tradeoff designs: one is the tradeoff between energy efficiency and harvested energy and the other is the tradeoff between energy efficiency and harvesting efficiency. Multiobjective optimization is used to solve the tradeoff problems. To simplify the original problems, we propose two schemes to obtain the lower bounds of the objective functions. The sensing threshold, sensing time, and transmit power of SU are jointly optimized to solve the tradeoff problems. Efficient algorithms are proposed to derive these design parameters. Simulation results are presented to validate the effectiveness of the proposed algorithms, to show the two tradeoff designs, and to validate the effects of system parameters on these tradeoffs.
Autors: Hang Hu;Ying-Chang Liang;Hang Zhang;Boon-Hee Soong;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 6201 - 6214
Publisher: IEEE
 
» Collaboratively Training Sentiment Classifiers for Multiple Domains
Abstract:
We propose a collaborative multi-domain sentiment classification approach to train sentiment classifiers for multiple domains simultaneously. In our approach, the sentiment information in different domains is shared to train more accurate and robust sentiment classifiers for each domain when labeled data is scarce. Specifically, we decompose the sentiment classifier of each domain into two components, a global one and a domain-specific one. The global model can capture the general sentiment knowledge and is shared by various domains. The domain-specific model can capture the specific sentiment expressions in each domain. In addition, we extract domain-specific sentiment knowledge from both labeled and unlabeled samples in each domain and use it to enhance the learning of domain-specific sentiment classifiers. Besides, we incorporate the similarities between domains into our approach as regularization over the domain-specific sentiment classifiers to encourage the sharing of sentiment information between similar domains. Two kinds of domain similarity measures are explored, one based on textual content and the other one based on sentiment expressions. Moreover, we introduce two efficient algorithms to solve the model of our approach. Experimental results on benchmark datasets show that our approach can effectively improve the performance of multi-domain sentiment classification and significantly outperform baseline methods.
Autors: Fangzhao Wu;Zhigang Yuan;Yongfeng Huang;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jul 2017, volume: 29, issue:7, pages: 1370 - 1383
Publisher: IEEE
 
» Combined Model for Simulating the Effect of Transients on a Damaged Rotor Cage
Abstract:
The expansion of the transient operation of electrical machines as, for instance, in vehicle traction applications, demands an accurate computation of the thermal behavior under these conditions in order to enhance the economy of the design and provide a precise estimation of the overload capacity. In addition, heavy transients have been identified as specially damaging for the rotor cage of large induction motors. The aim of this paper is the development of a model able to simulate in detail the thermal and mechanical effects of a heavy transient on an induction's motor rotor featuring a damaged (with a reduced section on one of its ends) rotor bar. Some preliminary results that provide a qualitative understanding of the development of a bar breakage during a fatigue test are presented.
Autors: Vicente Climente-Alarcon;Devi Nair;Ravi Sundaria;Jose A. Antonino-Daviu;Antero Arkkio;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3528 - 3537
Publisher: IEEE
 
» Combined Radar–Radiometer Surface Soil Moisture and Roughness Estimation
Abstract:
A robust physics-based combined active–passive (C-AP), or active–passive, surface soil moisture and roughness estimation methodology is presented. Soil moisture and roughness retrieval is performed via optimization, i.e., minimization, of a joint objective function, which constrains similar resolution radar and radiometer observations simultaneously. A data-driven and noise-dependent regularization term has also been developed to automatically regularize and balance corresponding radar and radiometer contributions to achieve optimal soil moisture retrievals. It is shown that in order to compensate for measurement and observation noise, as well as forward model inaccuracies, in C-AP estimation, surface roughness can be considered a free parameter. Extensive Monte Carlo numerical simulations and assessment using field data have been performed both to evaluate the algorithm’s performance and to demonstrate soil moisture estimation. Unbiased root mean squared errors range from 0.18 to 0.03 cm3/cm3 for two different land-cover types of corn and soybean. In summary, in the context of soil moisture retrieval, the importance of consistent forward emission and scattering development is discussed and presented.
Autors: Ruzbeh Akbar;Michael H. Cosh;Peggy E. O’Neill;Dara Entekhabi;Mahta Moghaddam;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jul 2017, volume: 55, issue:7, pages: 4098 - 4110
Publisher: IEEE
 
» Combined Variable Speed Limit and Lane Change Control for Highway Traffic
Abstract:
Variable speed limit (VSL) control of highway traffic is expected to improve traffic mobility, safety, and environment, especially during incidents. However, most existing VSL controllers show significant benefits in macroscopic analysis but little improvement in microscopic simulations in terms of traffic mobility. We demonstrate that the lack of improvement for travel time in many incident cases is due to lane changes that are taking place close to the bottleneck leading to severe capacity drop, which is not adequately captured by most macroscopic models. In this paper, we develop a combined lane change and VSL control scheme, which generates consistent improvements both with macroscopic and microscopic models. The lane change controller generates lane change recommendations upstream the incident or bottleneck in order to reduce the effect of the capacity drop. The VSL controller is developed using a feedback linearization approach based on the cell transmission macroscopic model and is shown analytically to guarantee exponential convergence to the optimum equilibrium point. Microscopic Monte Carlo simulations of traffic on the I-710 freeway were used to demonstrate that this combined control strategy is able to generate consistent improvements with respect to travel time, safety, and environmental impact under different traffic conditions and incident scenarios.
Autors: Yihang Zhang;Petros A. Ioannou;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Jul 2017, volume: 18, issue:7, pages: 1812 - 1823
Publisher: IEEE
 
» Comments on “Verifiable and Exculpable Outsourced Attribute-Based Encryption for Access Control in Cloud Computing”
Abstract:
Recently in IEEE Transactions on Dependable and Secure Computing (TDSC) (doi: 10.1109/TDSC.2015.2499755), Ma et al. proposed a new construction of attribute-based encryption (ABE) which can outsource the complicated encryption task to Encryption Service Provider (ESP) in a verifiable manner. Despite the authors claimed that the results of the outsourced encryption can be checked by the user, we show that Ma et al.’s proposal fails to provide the verifiability property for outsourced encryption, the most essential security goal that a verifiable computation scheme should achieve. Specifically, by giving concrete attacks, we demonstrate that the ESP can return forged intermediate ciphertext to the user without being detected.
Autors: Hu Xiong;Jianfei Sun;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Jul 2017, volume: 14, issue:4, pages: 461 - 462
Publisher: IEEE
 
» Compact and Multiband Electromagnetic Bandgap Structures With Adjustable Bandgaps Derived From Branched Open-Circuit Lines
Abstract:
Branched open-circuit lines are introduced for artificial negative-permittivity media, which is a type of metamaterial, to simultaneously achieve compact unit cells and adjustable bandgaps to cover multiband frequencies. Our electromagnetic bandgap (EBG) structures, the unit cells of which are under of the wavelength in a substrate, were designed to display characteristic effects, including bandgap-separation control and enhancement of the bandgap width. We analytically and experimentally investigated these effects. The compactness is derived from the length-dependent resonances of the open-circuit line instead of inductance-capacitance resonances, and the adjustable bandgaps originate from the introduction of the branched shape, which destroys the periodic capactive-inductive-impedance alternation of not-branched open-circuit lines. The proposed EBG structures are highly promising for frequency-selective devices, such as for electromagnetic noise suppression in power distribution networks.
Autors: Yoshiaki Kasahara;Hiroshi Toyao;Eiji Hankui;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2017, volume: 65, issue:7, pages: 2330 - 2340
Publisher: IEEE
 
» Compact First-Order Probe for Spherical Near-Field Antenna Measurements at Low Frequencies
Abstract:
Guidelines for designing compact and lightweight first-order probes for spherical near-field antenna measurements at frequencies below 1 GHz that exploit first-order properties of electrically small self-resonant radiators combined into superdirective endfire arrays are established theoretically, exemplified numerically, and validated experimentally. A prototype of the probe designed to operate at a central frequency of 435 MHz exhibits the impedance bandwidth of 15 MHz with a directivity of more than 9 dBi and parasitic spherical modes suppressed to at least −42 dB. The probe height is just 343 mm above a 720-mm circular ground plane and weighs about 5 kg.
Autors: Oleksiy S. Kim;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3684 - 3690
Publisher: IEEE
 
» Compact Modeling for Silicon Photonic Heterogeneously Integrated Circuits
Abstract:
Photonic-integrated circuits fabricated on a heterogeneously integrated silicon platform have demonstrated record levels of integration and communication capacity. As photonic-integrated circuits become larger and more complex, designing and analyzing them demand modeling and simulation methodologies employed in matured electronic design automation. In this paper, the development of compact models for the building blocks of a fabricated optical network-on-a-chip is introduced. These models are implemented in both SPICE-compatible electronics design automation tools and dedicated photonic-circuit simulators. Model validation is conducted at both device and link levels, allowing the circuit designer to study the impact of individual device design on the overall link performance, paving the path for model-based design optimization of photonic-integrated circuits.
Autors: Zeyu Zhang;Rui Wu;Yuyang Wang;Chong Zhang;Eric J. Stanton;Clint L. Schow;Kwang-Ting Cheng;John E. Bowers;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2017, volume: 35, issue:14, pages: 2973 - 2980
Publisher: IEEE
 
» Compact Modeling of Drain Current Thermal Noise in FDSOI MOSFETs Including Back-Bias Effect
Abstract:
In this paper, we present an analytical charge-based model for thermal noise power spectral density in fully depleted silicon on insulator (FDSOI) MOSFETs. Two important aspects particular to FDSOI technology, namely, different inversion charges and different effective mobilities at front and back interfaces, are considered in the model. Proposed model is valid from weak to strong inversion regions of operation. Velocity saturation and channel length modulation are also incorporated to properly capture the excess noise in deep submicrometer MOSFETs. To test the quality of the model, standard benchmark tests are performed and asymptotic behavior of the model is validated in all regions of operation. The model is implemented in SPICE and validated with calibrated TCAD simulations as well as with experimental data of high frequency noise for wide range of back biases.
Autors: Yogendra Sahu;Pragya Kushwaha;Avirup Dasgupta;Chenming Hu;Yogesh Singh Chauhan;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2017, volume: 65, issue:7, pages: 2261 - 2270
Publisher: IEEE
 
» Compact Modeling of Gate Capacitance in III–V Channel Quadruple-Gate FETs
Abstract:
In this paper, we present a compact model for charge density and gate capacitance for low effective mass channel material based quadruple-gate FETs (QGFETs). The proposed model accounts for the effect of quantum capacitance and conduction band non-parabolicity, which are important in FETs comprised of the low effective mass channel material. In modeling of QGFET, we propose and use a new form of Fermi–Dirac integral of order 1/2, which matches closely with the numerical data. Our model for the charge density and gate capacitance is compared with three-dimensional technology computer aided design (TCAD) simulations data, and shows excellent match. The proposed explicit compact model can be easily employed in efficient exploration of circuits based on the low effective mass QGFET nanowires.
Autors: Chandan Yadav;Mohit D. Ganeriwala;Nihar R. Mohapatra;Amit Agarwal;Yogesh Singh Chauhan;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jul 2017, volume: 16, issue:4, pages: 703 - 710
Publisher: IEEE
 
» Compact Wideband Bandpass Filter for TETRA Band Applications
Abstract:
This letter proposes a compact wideband bandpass filter using Short Circuited line Loaded Triangular Stub Resonator (SCLTR). The SCLTR makes the filter compact and simultaneously shifts the harmonics to higher frequencies. Six transmission poles generated by six resonators provide wide passband bandwidth and three Transmission Zeros (TZs) escalate the selectivity of the bandpass filter response. Two transmission zeros are created by virtue of Simultaneous Electric and Magnetic Coupling (SEMC) and one because of source to load cross coupling. The designed and fabricated filter is very compact with a size of , providing −3 dB fractional bandwidth of 20.5% and wide stopband bandwidth from 0.42 to 1.55 GHz. The experimental results are in compliance with the simulated results, which show that the filter is viable for practical use.
Autors: Vinay Kumar Killamsetty;Biswajeet Mukherjee;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2017, volume: 27, issue:7, pages: 630 - 632
Publisher: IEEE
 
» Compact Wideband LNA With Gain and Input Matching Bandwidth Extensions by Transformer
Abstract:
This letter presents a compact wideband low-noise amplifier (LNA) with utilizing the transformers for gain and input matching bandwidth extensions based on the source degeneration topology. The wideband gain response is achieved by using a transformer gate–drain feedback technique to peak the gain at high frequency while the wideband input matching is obtained by employing a new transformer-based input matching network to produce two resonant points separately located at low and high frequencies within the operating band. Implemented in 65-nm CMOS process, the proposed LNA shows a measured peak gain of 10.2 dB with its 3-dB bandwidth ranging from 15.8 to 30.3 GHz and minimum noise figure of 3.3 dB. Taking advantage of the superior compactness from the transformer-based techniques, the LNA occupies very compact chip area of only 0.18 mm2, exhibiting as one of the most compact wideband LNAs.
Autors: Pei Qin;Quan Xue;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2017, volume: 27, issue:7, pages: 657 - 659
Publisher: IEEE
 
» Comparison of Spectral Estimation Methods for Rapidly Varying Currents Obtained by High-Frequency Radar
Abstract:
A comparative study of the periodogram method and high-resolution techniques (the autoregressive and multiple signal classification methods) for current mapping by a high-frequency (HF) surface wave radar is undertaken for the case of 66-s-long data. This analysis is extended from a previous study that used the commonly adopted 6–13-min coherent integration times. This reduction in the sample size will result in poor Doppler resolution and reduction in signal-to-noise ratio (SNR) for the conventional periodogram method. Two Bragg-peak identification methods for current estimation, the conventional centroid method and the symmetric-peak-sum (SPS) method, are examined in conjunction with each of the spectral estimation techniques. A weighted sum of the current estimates using the two Doppler shift identification methods is also recommended to provide a lower root mean square (RMS) difference. The weight is optimized using a genetic algorithm. Field data comparison with current measurements obtained from a current meter indicates that the high-resolution spectral estimation method is capable of providing the same RMS difference level for short and long time series, while the RMS difference for currents obtained from the periodogram method increases dramatically for short time series. Significant improvement in the current velocities retrieved from a short time series indicates the potential for measuring rapidly changing currents using the suggested technique.
Autors: Wei Wang;Eric W. Gill;Weimin Huang;
Appeared in: IEEE Journal of Oceanic Engineering
Publication date: Jul 2017, volume: 42, issue:3, pages: 556 - 565
Publisher: IEEE
 
» Complementary Networking for C-RAN: Spectrum Efficiency, Delay and System Cost
Abstract:
Cloud radio access networks (C-RANs) architecture is a cost-efficient and energy-efficient solution for increasing the capacity of the cellular network. In order to adapt the traffic and reduce the system cost, we propose complementary networking architecture for the C-RAN, which takes advantage of both the C-RAN and traditional base stations (BSs).We propose combining the Neyman-Scott cluster process and the Poisson hole process to model the architecture; then, the interference in the large-scale network with cooperation is well characterized through the Poisson point process approximation. By mixing the two multiple association mechanisms, i.e., the RRH-selection mode and the cooperation mode, we explore the tradeoffs between the area spectrum efficiency (ASE), the mean delay, and the system cost both analytically and numerically. The results reveal that the mean delay is negative correlated to the ASE for small ASE and is reversed for large ASE, while the cost is always positively correlated to the ASE. The cooperation mode increases the useful signal as well as the interference, which becomes dominant when the radius of the RRH cluster is large. The proportion of sub-frames operating in the two modes can be configured to tradeoff the ASE, the mean delay, and the cost.
Autors: Yi Zhong;Tony Q. S. Quek;Wenyi Zhang;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4639 - 4653
Publisher: IEEE
 
» Complete Characterization of Generalized Bent and 2k-Bent Boolean Functions
Abstract:
In this paper, we investigate properties of generalized bent Boolean functions and -bent (i.e., negabent, octabent, hexadecabent, et al.) Boolean functions in a uniform framework. From the Hadamard matrices, Hodžić and Pasalic presented sufficient conditions for generalized bent functions. Using cyclotomic fields and the decomposition of generalized bent functions, we generalize their results, prove that Hodžić and Pasalic’s conditions of generalized bent functions are not only sufficient but also necessary, and completely characterize generalized bent functions in terms of their component functions. Furthermore, we present a secondary construction of bent functions or semi-bent functions from generalized bent functions. Finally, we give the relations of generalized bent functions and -bent functions, demonstrate that -bent functions are actually a special class of generalized bent functions, and completely characterize -bent functions.
Autors: Chunming Tang;Can Xiang;Yanfeng Qi;Keqin Feng;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4668 - 4674
Publisher: IEEE
 
» Comprehending Cognitive Radios [Book\Software Reviews]
Abstract:
This book provides an excellent overview of all aspects of cognitive radio. While the book draws most of its examples from work done at Virginia Tech, the scope of the book is comprehensive. Its eight chapters lead readers from the basic definition of a cognitive radio through cognitive radio hardware and software and finally into the performance evaluation and application of a cognitive radio. This book is primarily for practicing engineers and managers, as it surveys the broad area of cognitive radio and includes a substantial reference list for further research. For anyone interested in radio design, this book has much to recommend.
Autors: Alfy Riddle;
Appeared in: IEEE Microwave Magazine
Publication date: Jul 2017, volume: 18, issue:5, pages: 120 - 132
Publisher: IEEE
 
» Comprehensive Analysis on Electrical Characteristics of Pi-Gate Poly-Si Junctionless FETs
Abstract:
In this paper, the electrical characteristics of the Pi-gate junctionless FETs (PG JL FETs) with the in situ n+ doped poly-Si (DP-Si) fin-channels have been experimentally investigated and comprehensively discussed. The subthreshold behavior and threshold voltage of the PG JL FETs are sensitive to the channel dimensions, especially the channel width. The crystallinity, carrier mobility, and effective carrier concentration in the DP-Si films are dependent on the initial DP-Si film thicknesses, which directly influence the on current and threshold voltage of the PG JL FETs. Based on an evaluation on the subthreshold behavior and the driving current, we found that the PG JL FETs with the low/high aspect ratio (A.R. = channel thickness/channel width) are separately suitable for the low-power/high-performance applications. Among these PG JL FETs, the device with a proper A.R. (3.35) exhibits a relatively steep subthreshold swing (S.S.) of 66 mV/decade and the highest ON/OFF currents ratio ( of ( V). These devices are very promising candidates for future multifunctional 3-D integrated circuit applications.
Autors: Dong-Ru Hsieh;Jer-Yi Lin;Po-Yi Kuo;Tien-Sheng Chao;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2017, volume: 64, issue:7, pages: 2992 - 2998
Publisher: IEEE
 
» Comprehensive Comparison of Compact UWB Antenna Performance by Means of Multiobjective Optimization
Abstract:
An optimization-based procedure for comprehensive performance comparison of alternative compact UWB antenna topologies is discussed. The assessment of the antenna performance is conducted with respect to the structure size and its reflection response. More specifically, the best possible tradeoffs between these two figures of merit are identified through multiobjective optimization at the level of full-wave electromagnetic (EM) simulation. Analysis of Pareto-optimal designs obtained for various antenna topologies allow for their fair comparison; particularly in terms of the minimum size, they can be designed for (assuming acceptable reflection response levels) or the best attainable reflection characteristics. For the sake of computational efficiency, the multiobjective optimization algorithm utilized in this paper exploits sequential domain patching technique and variable-fidelity EM simulation models, which is a fully automated procedure that permits finding Pareto set representations at the cost corresponding to about a hundred of high-fidelity EM analyses of a given structure. The proposed approach is demonstrated using three topologies of compact UWB-monopole antennas. Comparison of antenna with respect to three objectives (also including total efficiency) is also discussed. Simulation results are verified using experimental data.
Autors: Slawomir Koziel;Adrian Bekasiewicz;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3427 - 3436
Publisher: IEEE
 
» Compressed Sensing With Prior Information: Strategies, Geometry, and Bounds
Abstract:
We address the problem of compressed sensing (CS) with prior information: reconstruct a target CS signal with the aid of a similar signal that is known beforehand, our prior information. We integrate the additional knowledge of the similar signal into CS via - and - minimization. We then establish bounds on the number of measurements required by these problems to successfully reconstruct the original signal. Our bounds and geometrical interpretations reveal that if the prior information has good enough quality, - minimization improves the performance of CS dramatically. In contrast, - minimization has a performance very similar to classical CS, and brings no significant benefits. In addition, we use the insight provided by our bounds to design practical schemes to improve prior information. All our findings are illustrated with experimental results.
Autors: João F. C. Mota;Nikos Deligiannis;Miguel R. D. Rodrigues;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4472 - 4496
Publisher: IEEE
 
» Compressed Sensing-Aided Downlink Channel Training for FDD Massive MIMO Systems
Abstract:
There is much discussion in industry and academia about possible technical solutions to address the growth in demand for wireless broadband. Massive multiple-input multiple-output (MIMO) systems are one of the most popular solutions to addressing this broadband demand in fifth generation (5G) cellular systems. Massive MIMO systems employ tens or hundreds of antennas at the base station to enable advanced multiuser MIMO communications. To reap the massive MIMO throughput gain, coherent transmission exploiting accurate channel state information at the transmitter is required. While it is expected that many 5G systems will employ frequency division duplexing (FDD), channel sounding for FDD systems requires a large pilot overhead, which usually scales proportionally to the number of transmit antennas. To resolve this problem, a compressed sensing (CS)-aided channel estimation scheme is proposed, which exploits the observation that the channel statistics change slowly in time. By utilizing a conventional least squares approach and a CS technique simultaneously, the proposed scheme reduces the pilot overhead. Simulation results show that the proposed scheme can estimate the channel with a reduced pilot overhead even when conventional CS cannot be applied.
Autors: Yonghee Han;Jungwoo Lee;David J. Love;
Appeared in: IEEE Transactions on Communications
Publication date: Jul 2017, volume: 65, issue:7, pages: 2852 - 2862
Publisher: IEEE
 
» Compressive Sensing Reconstruction for Video: An Adaptive Approach Based on Motion Estimation
Abstract:
This paper focuses on the problem of causally reconstructing compressive sensing (CS) captured video. The state-of-the-art causal approaches usually assume that the signal support is static or changing sufficiently slowly over time, where magnetic resonance imaging is widely used as a motivating example. However, such an assumption is too restrictive for many other video applications, where the signal support changes rapidly. In this paper, we propose a framework that combines motion estimation (ME), the Kalman filter (KF), and CS to adapt the reconstruction process to motions in the video so that the slowly changing assumption on the signal support is relaxed and consequently is more suitable for video reconstruction. Explicit and implicit ME are designed to provide motion-aware predictions, upon which a modified KF procedure is applied. Furthermore, three CS algorithms with embedded ME and KF are developed, and theoretical analyses are conducted via reconstruction error upper bounds to characterize the various factors that affect reconstruction accuracy. Extensive simulations utilizing actual videos are carried out, and the superiority of our methods is demonstrated.
Autors: Xin Ding;Wei Chen;Ian J. Wassell;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jul 2017, volume: 27, issue:7, pages: 1406 - 1420
Publisher: IEEE
 
» Computationally Efficient Analysis of Double PM-Rotor Radial-Flux Eddy Current Couplers
Abstract:
In this study, a semianalytical calculation method for obtaining 3-D solutions for the torque of radial-flux permanent magnet eddy current couplers is presented. In this way, the use of computationally expensive transient 3-D finite element solutions is avoided, which is very important when it comes to the design optimization of these machines. The proposed analytical method takes the effect of flux density harmonics into account. The 3-D end-effects are taken into account by using Russell's coefficient. The accuracy of the proposed semianalytical calculation method is evaluated against extreme variation of machine dimensions. The Russell end-effect factor is evaluated and found to be inaccurate for axially short and radially large couplers. A prototype coupler with different conductors was tested to validate the proposed semianalytical torque calculation method.
Autors: Abram S. Erasmus;Maarten J. Kamper;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3519 - 3527
Publisher: IEEE
 
» Computationally Efficient Tolerance Analysis of the Cogging Torque of Brushless PMSMs
Abstract:
This paper investigates the impact of tolerances related to permanent magnets on the cogging torque performance of Permanent magnet synchronous machines (PMSMs). These machines usually show a considerable sensitivity regarding tolerances for geometric dimensions and material characteristics. A consistent approach is presented in order to minimize the computational effort for evaluating the sensitivity, robustness, or reliability. Thereby, design of experiments is used to minimize the required number of finite element simulations. In this work, a Box–Behnken-based approach is considered. Subsequently, a surrogate modeling technique based on a second-order equation is applied. As a consequence, a reduction of the computational cost by 96% is achieved. The obtained results are compared with outcomes solely derived by means of finite element computations and very good agreement is observed. This is illustrated by providing the probability distribution of the cogging torque for the considered machine design. In addition, the cumulative distribution is presented, which usually is applied for analyzing the reliability. Considering the analysis of the impact of tolerances as part of optimization scenarios increases the number of designs to be analyzed by at least one degree of magnitude. The obtained results look promising for achieving this at feasible computational cost.
Autors: Gerd Bramerdorfer;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3387 - 3393
Publisher: IEEE
 
» Computer-Aided Diagnosis of Focal Liver Lesions Using Contrast-Enhanced Ultrasonography With Perflubutane Microbubbles
Abstract:
This paper proposes an automatic classification method based on machine learning in contrast-enhanced ultrasonography (CEUS) of focal liver lesions using the contrast agent Sonazoid. This method yields spatial and temporal features in the arterial phase, portal phase, and post-vascular phase, as well as max-hold images. The lesions are classified as benign or malignant and again as benign, hepatocellular carcinoma (HCC), or metastatic liver tumor using support vector machines (SVM) with a combination of selected optimal features. Experimental results using 98 subjects indicated that the benign and malignant classification has 94.0% sensitivity, 87.1% specificity, and 91.8% accuracy, and the accuracy of the benign, HCC, and metastatic liver tumor classifications are 84.4%, 87.7%, and 85.7%, respectively. The selected features in the SVM indicate that combining features from the three phases are important for classifying FLLs, especially, for the benign and malignant classifications. The experimental results are consistent with CEUS guidelines for diagnosing FLLs. This research can be considered to be a validation study, that confirms the importance of using features from these phases of the examination in a quantitative manner. In addition, the experimental results indicate that for the benign and malignant classifications, the specificity without the post-vascular phase features is significantly lower than the specificity with the post-vascular phase features. We also conducted an experiment on the operator dependency of setting regions of interest and observed that the intra-operator and inter-operator kappa coefficients were 0.45 and 0.77, respectively.
Autors: Satoshi Kondo;Kazuya Takagi;Mutsumi Nishida;Takahito Iwai;Yusuke Kudo;Kouji Ogawa;Toshiya Kamiyama;Hitoshi Shibuya;Kaoru Kahata;Chikara Shimizu;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jul 2017, volume: 36, issue:7, pages: 1427 - 1437
Publisher: IEEE
 
» Computing Robust Controlled Invariant Sets of Linear Systems
Abstract:
We consider controllable linear discrete-time systems with bounded perturbations and present two methods to compute robust controlled invariant sets. The first method tolerates an arbitrarily small constraint violation to compute an arbitrarily precise outer approximation of the maximal robust controlled invariant set, while the second method provides an inner approximation. The outer approximation scheme is -complete, given that the constraint sets are formulated as finite unions of polytopes.
Autors: Matthias Rungger;Paulo Tabuada;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3665 - 3670
Publisher: IEEE
 
» Concurrent Learning for Parameter Estimation Using Dynamic State-Derivative Estimators
Abstract:
A concurrent learning (CL)-based parameter estimator is developed to identify the unknown parameters in a nonlinear system. Unlike state-of-the-art CL techniques that assume knowledge of the state derivative or rely on numerical smoothing, CL is implemented using a dynamic state-derivative estimator. A novel purging algorithm is introduced to discard possibly erroneous data recorded during the transient phase for CL. Asymptotic convergence of the error states to the origin is established under a persistent excitation condition, and the error states are shown to be uniformly ultimately bounded under a finite excitation condition.
Autors: Rushikesh Kamalapurkar;Benjamin Reish;Girish Chowdhary;Warren E. Dixon;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3594 - 3601
Publisher: IEEE
 
» Condition-Based Less-Error Data Selection for Robust and Accurate Mass Measurement in Large-Scale Hydraulic Manipulators
Abstract:
This paper proposes a practical scheme for measuring the mass of an object grasped by the end-effector of a large-scale hydraulic manipulator. Such a measurement system requires high accuracy and robustness considering the nonlinearity and uncertainty in hydraulic pressure-based force measurement during rigorous outdoor work. It is thus difficult to precisely model system behaviors and completely remove error force components (white-box modeling) under such conditions, so our scheme adopts a less-error data selection approach to relatively improving the accuracy and reliability of the measurand (gray-box modeling). It first removes dominant error forces, i.e., gravity and dynamic friction forces, then defines the on-load state by evaluating measurement conditions to omit data in indeterminate conditions, then extracts data during the object-grasp state identified by a grasp motion model and removes high-frequency components by a simple low-pass filter, and finally integrates data from multiple sensors using the posture-based priority and averages all selected data. Evaluation experiments were conducted using an instrumented hydraulic arm. Results indicate that our scheme can precisely measures the mass of the grasped object under various detection conditions with fewer errors.
Autors: Mitsuhiro Kamezaki;Hiroyasu Iwata;Shigeki Sugano;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jul 2017, volume: 66, issue:7, pages: 1820 - 1830
Publisher: IEEE
 
» Congestion Relief in Subway Areas by Tuning Uplink Power Control in LTE
Abstract:
Providing an adequate quality of service in subway areas is a challenging task in cellular networks, due to the complexity of the indoor propagation and the effects of group mobility. Thus, it is common that traffic congestion appears in subway cells. In this paper, a self-tuning method for uplink power control (ULPC) parameters is proposed to solve congestion problems in long-term evolution (LTE) cells located in a subway network. First, a thorough analysis of congestion phenomena in LTE subway cells is presented. The aim of the analysis is to show how uplink performance is severely degraded with group mobility in subway cells. Then, a heuristic algorithm is proposed to tune the nominal power parameter in ULPC on a cell basis to solve localized congestion problems. The aim of the algorithm is to exploit cell isolation by increasing user transmit power to improve system spectral efficiency and thus reduce the average cell load. Field trial results show that the algorithm significantly improves network accessibility and retainability in subway scenarios without any hardware upgrade.
Autors: Ana Belén Vallejo-Mora;Matías Toril;Salvador Luna-Ramírez;Adriano Mendo;Salvador Pedraza;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 6489 - 6497
Publisher: IEEE
 
» Connectivity of Magnetic Induction-Based Ad Hoc Networks
Abstract:
Magnetic induction (MI) has been proven to be an efficient wireless communication technique for overcoming the transmission challenges in some very harsh propagation environments, such as underground, underwater, etc. For a random distributed MI ad hoc network in a 3-D space composed of uniform medium, we propose a method for determining the required node density and transmitting power that creates an almost surely fully connected network. For which we involve an MI path-loss model and consider the effect of eddy currents, the effective coverage space and the expected node degree of an MI node are then calculated by a Lambert W-function-based integration. Finally, we propose optimized frequency selection methods for improving the connectivity of MI networks. In addition to an ideal frequency-switching optimization method, we provide for engineering applications a practical frequency-fixed optimization method, which is based on the gradient descent algorithm, where an improved initialization is used to reduce iterations.
Autors: Zhengqing Zhang;Erwu Liu;Xinyu Qu;Rui Wang;Honglei Ma;Zhi Sun;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4181 - 4191
Publisher: IEEE
 
» Consensus Control for a Multi-Agent System With Integral-Type Event-Triggering Condition and Asynchronous Periodic Detection
Abstract:
In this paper, we use an event-triggered control methode to study the consensus problem for an asynchronous distributed multi-agent system. An integral-type event-triggering condition is proposed. Each agent periodically checks its triggering condition by its own clock. When the triggering condition for an agent is satisfied, then control inputs of this agent and its neighbors are updated. Based on local information, we present the consensus protocol, and using Lyapunov's methods, we show that all agents asymptotically reach an agreement on states. Finally, experiments are presented to demonstrate the effectiveness of our proposed protocol.
Autors: Aiping Wang;Bingxian Mu;Yang Shi;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5629 - 5639
Publisher: IEEE
 
» Consideration of Existing Capacity in Screening Curve Method
Abstract:
The screening curve method (SCM) is an intuitive and fast model that estimates the least-cost generation mix for generation planning purposes. It calculates an economically adapted generation mix for a target load duration curve within a few seconds, but lacks many detailed considerations of the generation system. In order to improve SCM, many developments have been made in recent years. However, one of the biggest limitations had always been that the SCM assumed all capacity to be new with no existing capacity. This drawback made SCM less useful compared to other generation planning models. In this paper, we develop a direct way to model existing capacity in SCM. The proposed method is studied in this paper and is illustrated with an example. Finally, an ERCOT year 2030 case is simulated.
Autors: Tong Zhang;Ross Baldick;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 3038 - 3048
Publisher: IEEE
 
» Constraint-Tightening and Stability in Stochastic Model Predictive Control
Abstract:
Constraint tightening to non-conservatively guarantee recursive feasibility and stability in Stochastic Model Predictive Control is addressed. Stability and feasibility requirements are considered separately, highlighting the difference between existence of a solution and feasibility of a suitable, a priori known candidate solution. Subsequently, a Stochastic Model Predictive Control algorithm which unifies previous results is derived, leaving the designer the option to balance an increased feasible region against guaranteed bounds on the asymptotic average performance and convergence time. Besides typical performance bounds, under mild assumptions, we prove asymptotic stability in probability of the minimal robust positively invariant set obtained by the unconstrained LQ-optimal controller. A numerical example, demonstrating the efficacy of the proposed approach in comparison with classical, recursively feasible Stochastic MPC and Robust MPC, is provided.
Autors: Matthias Lorenzen;Fabrizio Dabbene;Roberto Tempo;Frank Allgöwer;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3165 - 3177
Publisher: IEEE
 
» Context-Aware Energy Saving System With Multiple Comfort-Constrained Optimization in M2M-Based Home Environment
Abstract:
Most previous work in household energy conservation has focused on rule-based home automation to achieve energy savings, with relatively few researchers focusing on context-aware technologies. As a result, user comfort is often disregarded and few solutions handle decision conflicts caused by multiple activities undertaken by multiple users. The main contribution of this work is twofold. First, a comprehensive human-centric and context-aware comfort index is proposed to evaluate how users feel under particular environmental conditions with regard to thermal, illumination, and appliance-usage preferences. Second, the energy savings is formulated into an optimization problem to minimize the total energy consumption, even under multiple user comfort constraints. Short-term evaluation in our simulated home environment resulted in energy savings of at least 28.98%. Long-term evaluation using a home simulator resulted in energy savings of 33.7%. Most importantly, the energy savings in both situations was achieved under multiple user comfort constraints, representing a truly human-centric living environment.
Autors: Ching-Hu Lu;Chao-Lin Wu;Mao-Yung Weng;Wei-Chen Chen;Li-Chen Fu;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jul 2017, volume: 14, issue:3, pages: 1400 - 1414
Publisher: IEEE
 
» Contingency-Constrained Unit Commitment With Intervening Time for System Adjustments
Abstract:
The -1-1 contingency reliability criterion considers the consecutive loss of two components in a power system, with intervening time for system adjustments between the two losses. In this paper, we consider the problem of optimizing generation unit while ensuring the -1-1 criterion. Due to the coupling of time periods associated with consecutive component losses, the resulting problem yields a very large-scale mixed-integer linear optimization model. For efficient solution, we introduce a novel branch-and-cut algorithm using a temporally decomposed bilevel separation oracle. The model and algorithm are assessed using multiple IEEE test systems, and a comprehensive analysis is performed to compare system performance across different contingency criteria. Computational results demonstrate the value of considering intervening time for system adjustments in terms of total cost and system robustness.
Autors: Zhaomiao Guo;Richard Li-Yang Chen;Neng Fan;Jean-Paul Watson;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 3049 - 3059
Publisher: IEEE
 
» Continuous Blood Viscosity Monitoring System for Cardiopulmonary Bypass Applications
Abstract:
This paper proposes an algorithm that estimates blood viscosity during cardiopulmonary bypass (CPB) and validates its application in clinical cases. The proposed algorithm involves adjustable parameters based on the oxygenator and fluid types and estimates blood viscosity based on pressure-flow characteristics of the fluid perfusing through the oxygenator. This novel nonlinear model requires four parameters that were derived by in vitro experiments. The results estimated by the proposed method were then compared with a conventional linear model to demonstrate the former's optimal curve fitting. The viscosity estimated using the proposed algorithm and the viscosity measured using a viscometer were compared for 20 patients who underwent mildly hypothermic CPB. The developed system was applied to ten patients, and was recorded for comparisons with hematocrit and blood temperature. The residual sum of squares between the two curve fittings confirmed the significant difference, with p < 0.001. and showed a very strong correlation with = 0.9537 and p < 0.001. Regarding the mean coefficient of determination for all cases, the hematocrit and temperature showed weak correlations at 0.33 ± 0.14 and 0.22 ± 0.21, respectively. For CPB measurements of all cases, was more th- n 98% distributed in the range from 1 to 3 mPa⋅s. This new system for estimating viscosity may be useful for detecting various viscosity-related effects that may occur during CPB.
Autors: Shigeyuki Okahara;Zu Soh;Satoshi Miyamoto;Hidenobu Takahashi;Shinya Takahashi;Taijiro Sueda;Toshio Tsuji;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jul 2017, volume: 64, issue:7, pages: 1503 - 1512
Publisher: IEEE
 
» Continuous Class-B/J Power Amplifier Using a Nonlinear Embedding Technique
Abstract:
This brief explores the design space for realizable solution of a broadband class-B/J continuous mode of power amplifier (PA). The PA is initially designed at the current-source reference plane with the correct voltage and current waveforms. The intrinsic impedances are then projected to the package reference plane using the model-based nonlinear-embedding technique. An insight is provided into engineering the extrinsic harmonic impedance to rotate clockwise on the Smith chart to be able to match it using a Foster circuit. It is concluded that decreasing the empirical parameter of a general class-B/J voltage equation with increasing frequency leads to a clockwise trajectory on the Smith chart of the second harmonic at the package plane. In order to validate the advantage of this analysis, the PA is implemented using a 15 W gallium nitride high electron mobility transistor in the frequency range of 1.3 to 2.4 GHz and drain efficiency between 63% and 72% in measurement was achieved over the entire bandwidth.
Autors: Samarth Saxena;Karun Rawat;Patrick Roblin;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2017, volume: 64, issue:7, pages: 837 - 841
Publisher: IEEE
 
» Continuous Fabrication of Highly Conductive and Transparent Ag Mesh Electrodes for Flexible Electronics
Abstract:
Flexible transparent conductive electrodes are essential components for flexible electronics and more functions are combined in such components for miniaturization and design flexibility. The embedded metal mesh, due to the merits of good transparency, conductivity, and flexibility, is regarded as a promising candidate for transparent conductive electrodes. This study reports a continuous fabrication approach of roll-to-roll ultraviolet-nanoimprint lithography (R2R UV-NIL) for the large-area fabrication of embedded Ag mesh electrodes on polyethylene terephthalate (PET) substrates. It has the potential to replace the vacuum-based metal deposition process in flexible transparent electrodes fabrication for large-area, high-throughput, and low-cost production. A R2R UV-NIL system is developed that consists of microchannels patterning stage, doctor blading stage, and Ag residual layer removing stage. A nickel mold for the R2R UV-NIL process is theoretically designed and practically developed. A prototype of embedded metal mesh has been fabricated using water-based, nanosilver paste, and the electrical and optical performance have been further improved by wet etching. The optical transmittance and the sheet resistance are 82.0% and 22.1 Ω/sq, respectively. The electrical and optical performance is excellent with a high value of 81. It is demonstrated that the R2R UV-NIL process is feasible for the large-area fabrication of embedded Ag mesh for flexible transparent electrodes.
Autors: Zhaozhao Wang;Peiyun Yi;Linfa Peng;Xinmin Lai;Jun Ni;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jul 2017, volume: 16, issue:4, pages: 687 - 694
Publisher: IEEE
 
» Contrasting Laser Power Requirements of Wavelength-Routed Optical NoC Topologies Subject to the Floorplanning, Placement, and Routing Constraints of a 3-D-Stacked System
Abstract:
A realistic assessment of optical networks-on-chip (ONoCs) can be performed only in the context of a comprehensive floorplanning strategy for the system as a whole, especially when the 3-D stacking of electronic and optical layers is implemented. This paper fosters layout-aware ONoC design by developing a physical mapping methodology for wavelength-routed ONoC topologies subject to the floorplanning, placement, and routing constraints that arise in a 3-D-stacked environment. As a result, this paper is able to compare the power efficiency and signal-to-noise ratio of ring-based versus filter-based wavelength-routed topologies as determined by their physical design flexibility.
Autors: Marta Ortín-Obón;Mahdi Tala;Luca Ramini;Víctor Viñals-Yufera;Davide Bertozzi;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jul 2017, volume: 25, issue:7, pages: 2081 - 2094
Publisher: IEEE
 
» Control and Performance of Five-Phase Dual Stator-Winding Induction Generator DC Generating System
Abstract:
In this paper, the five-phase dual stator-winding induction generator dc generating system with the static excitation controller is presented, and two kinds of control strategies for this system are proposed. In this generator, the cage-type rotor is employed, and two sets of five-phase windings are placed in the stator, namely, the power winding and control winding. Using the instantaneous power theory, the control-winding-flux-oriented control (CWFOC) strategy without harmonic injection is obtained. To improve power density, the CWFOC with harmonic injection is proposed as well. For these two strategies, the detailed implementation is studied. The results (simulation and experiment) support the correctness and effectiveness of the proposed control strategies, and the corresponding results show that, using the CWFOC strategy with harmonic injection, the output power of this system can be improved by about 11%.
Autors: Haijun Xu;Feifei Bu;Wenxin Huang;Yuwen Hu;Haozhe Liu;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5276 - 5285
Publisher: IEEE
 
» Control of Growth Modes by Carbon Mediation in Formation of Ge Quantum Dots on Si(100)
Abstract:
Control and mechanism analysis of a Ge quantum dot (QD) formation on a Si(100) substrate by using carbon (C)-mediated c(4 × 4) surface reconstruction (SR) and solid-phase epitaxy (SPE) methods is demonstrated. The Si surface was reconstructed via the formation of C–Si bonds before Ge deposition in the SR method, while the QDs were formed by annealing of an amorphous Ge/C/Si heterostructure in the SPE method. In the SR method, the QDs grew in the Volmer–Wever (VW) mode at C = 0.25 and 0.50 monolayer (ML), and in the Stranski–Krastanov (SK) mode at C = 0.75 ML. The VW-mode QDs were formed owing to the c(4 × 4) surface reconstruction that acted like a virtual partition for Ge nucleation. At C = 0.5 and 0.75 ML, it was confirmed that the C–Ge bonds were formed near the Ge/Si interface because the unreacted excessive C atoms remained at the Ge/Si interface. The formation of C–Ge bonds induced the strain relief of the Ge layer and acted to change the growth mode to the SK mode at C = 0.75 ML. On the other hand, in the SPE method, the QDs grew in the VW mode at C = 0.1 and 0.25 ML due to the Ge aggregation, and in the SK mode at C ≥ 0.4 ML. It was found that a large number of C–Ge bonds owing to the incorporation of C into the Ge layer during the SPE induced the formation of a wetting layer. Therefore, the reduction of the strain energy in the Ge layer occurred at the low C coverage and induced the transition to the SK mode. These results suggest that the growth modes of the QDs via C mediation are controllable in both methods by changing the amount of C used as the mediation layer owing to the change in the C binding states at the Ge&#- 002F;Si interface or in the Ge layer.
Autors: Yuhki Itoh;Tomoyuki Kawashima;Katsuyoshi Washio;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jul 2017, volume: 16, issue:4, pages: 595 - 599
Publisher: IEEE
 
» Controllability Analysis for a Networked Dynamic System With Autonomous Subsystems
Abstract:
This technical note investigates the controllability of networked dynamic systems of which some subsystems are not directly affected by external inputs (i.e., autonomous). The topology can be arbitrary, and every subsystem can have different dynamics and even different number of states, inputs and outputs. We show that to guarantee the controllability of the whole system, every subsystem should be controllable when isolated. We establish some necessary and sufficient conditions for the system to be controllable. These conditions essentially depend on the parameters of every subsystem separately or the strongly connected autonomous subsystems, which reduce significantly computation complexity for large-scale networked systems. We reveal that heterogenous networked systems under some assumptions can be separated into several independent subnetworks, such that the controllability of the whole system is equal to the controllability of each subnetwork. Based on these conditions, criteria that can be easily verified are given for the controllability of networked systems with some special topologies.
Autors: Yuan Zhang;Tong Zhou;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3408 - 3415
Publisher: IEEE
 
» Controlled Flooding of Fountain Codes
Abstract:
We consider a multihop network where a source node must reliably deliver a set of data packets to a given destination node. To do so, the source applies a fountain code and floods the encoded packets through the network, until they reach their destination or are lost in the process. We model the probability that the destination can recover the original transmissions from the received coded packets as a function of the network topology and of the code redundancy, and show that our analytical results predict the outcome of simulations very well. These results are employed to design distributed forwarding policies that achieve a good tradeoff between the success probability and the total number of transmissions required to advance a packet toward the destination. We finally develop in detail the case where intermediate relays can inject additional redundancy in the network, provided that they have successfully decoded the source packets.
Autors: Waqas Bin Abbas;Paolo Casari;Michele Zorzi;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4698 - 4710
Publisher: IEEE
 
» Controlling the Electron Coupled State in the Superlattice of PbS Quantum Dots by Replacing Ligands
Abstract:
We report that the emission wavelength of a superlattice of colloidal PbS quantum dots (QDs) was greatly lengthened on replacing their ligands with shorter ones. The long-period close packing was achieved with the aid of a pyramidal hole array prepared on a Si substrate using selective wet etching. The emission energy shift at the ground state was accompanied by an increase in the emission lifetime. These emission properties were attributed to the significant delocalization of the carrier wave function in the QD superlattice having long periodicity.
Autors: Kohki Mukai;Fumimasa Suetsugu;Keisuke Niwa;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jul 2017, volume: 16, issue:4, pages: 600 - 605
Publisher: IEEE
 
» Convergence Analysis of Cooperative Braking Control for Interconnected Vehicle Systems
Abstract:
Cooperative braking control is a very important operation in vehicle platoon control for developing intelligent transportation systems, which can effectively increase road capacity, decrease safety hazard, and avoid serial rear-end collisions. This paper focuses on cooperative braking control of autonomous vehicles, the objectives of which are to ensure intervehicles keep within the safe spacing range and rapidly, smoothly, and accurately stop at the desired target stopping positions with zero velocity. To achieve these goals, a three-vehicle platoon framework is presented and the corresponding dynamic model is established based on only information about front-end and rear-end sensors of vehicles, so communication is not needed. The explicit solutions on the three-vehicle platoon are derived by rigorous convergent analysis and detailed proof, such that intrinsic characteristic of the interconnected vehicles is revealed. The resulting convergent conditions and convergent rate are obtained under three cases including: 1) considering internal virtual forces; 2) considering external braking forces; and 3) considering both the internal virtual forces and external braking forces simultaneously. Moreover, an example is further provided to verify that the derived convergence conditions are effective and sufficient under the different controller parameter selection. These results can provide a solution for a wide class of interconnected systems and a guide for controller design to select control parameters in real engineering applications. Simulation results demonstrate the validity of the proposed control approaches.
Autors: Yonggui Liu;Bugong Xu;Yuehua Ding;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Jul 2017, volume: 18, issue:7, pages: 1894 - 1906
Publisher: IEEE
 
» Convex Parameterizations and Fidelity Bounds for Nonlinear Identification and Reduced-Order Modelling
Abstract:
Model instability and poor prediction of long-term behavior are common problems when modeling dynamical systems using nonlinear “black-box” techniques. Direct optimization of the long-term predictions, often called simulation error minimization, leads to optimization problems that are generally nonconvex in the model parameters and suffer from multiple local minima. In this paper, we present methods which address these problems through convex optimization, based on Lagrangian relaxation, dissipation inequalities, contraction theory, and semidefinite programming. We demonstrate the proposed methods with a model order reduction task for electronic circuit design and the identification of a pneumatic actuator from experiment.
Autors: Mark M. Tobenkin;Ian R. Manchester;Alexandre Megretski;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3679 - 3686
Publisher: IEEE
 
» ConvNet-Based Localization of Anatomical Structures in 3-D Medical Images
Abstract:
Localization of anatomical structures is a prerequisite for many tasks in a medical image analysis. We propose a method for automatic localization of one or more anatomical structures in 3-D medical images through detection of their presence in 2-D image slices using a convolutional neural network (ConvNet). A single ConvNet is trained to detect the presence of the anatomical structure of interest in axial, coronal, and sagittal slices extracted from a 3-D image. To allow the ConvNet to analyze slices of different sizes, spatial pyramid pooling is applied. After detection, 3-D bounding boxes are created by combining the output of the ConvNet in all slices. In the experiments, 200 chest CT, 100 cardiac CT angiography (CTA), and 100 abdomen CT scans were used. The heart, ascending aorta, aortic arch, and descending aorta were localized in chest CT scans, the left cardiac ventricle in cardiac CTA scans, and the liver in abdomen CT scans. Localization was evaluated using the distances between automatically and manually defined reference bounding box centroids and walls. The best results were achieved in the localization of structures with clearly defined boundaries (e.g., aortic arch) and the worst when the structure boundary was not clearly visible (e.g., liver). The method was more robust and accurate in localization multiple structures.
Autors: Bob D. de Vos;Jelmer M. Wolterink;Pim A. de Jong;Tim Leiner;Max A. Viergever;Ivana Išgum;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jul 2017, volume: 36, issue:7, pages: 1470 - 1481
Publisher: IEEE
 
» Cooperative Control for Moving-Target Circular Formation of Nonholonomic Vehicles
Abstract:
This note investigates the problem of moving-target circular formation of nonholonomic vehicles, such that the controlled vehicles orbit around a target moving with a time-varying velocity and maintain even spacing along the common circle. A cooperative controller is developed for each vehicle via local measurements only. The topology of the sensor graph may dynamically switch based on the relative positions between vehicles and the target. Moreover, measurements in the local Frenet-Serret frame of each vehicle rather than in a global coordinate frame are used. Finally, the effectiveness of the proposed controller is verified by the simulation results of an example.
Autors: Xiao Yu;Lu Liu;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3448 - 3454
Publisher: IEEE
 
» Cooperative Internet Access Using Helper Nodes and Opportunistic Scheduling
Abstract:
Having ubiquitous access to the Internet is becoming a necessity of life. Furthermore, we are witnessing a rapid increase in the amount of data requested by mobile users. Cooperative Internet access is a promising approach for addressing these demands, which gives the mobile devices the opportunity to receive help from other mobile devices in order to access the Internet. The helpers can download the data requested by the other users, called clients, through their cellular connections. Then, they transmit the downloaded data to the clients using Wi-Fi or Bluetooth connections. In this paper, we consider the problem of how to share the resources of helpers among a set of clients that request their assistance. Opportunistic scheduling is an effective method that uses the dynamic channel conditions to elevate the systems’ overall utilities. We propose an opportunistic scheduling algorithm in order to efficiently use the helper nodes and share them among the clients fairly. We propose a rate control and scheduling method in the case of using only Wi-Fi connections. We also propose a solution for the case of using Wi-Fi and Bluetooth at the same time. Through simulation results, we show the effectiveness of our cooperative downloading methods.
Autors: Pouya Ostovari;Jie Wu;Abdallah Khreishah;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 6439 - 6448
Publisher: IEEE
 
» Cooperative Management in Full-Truckload and Less-Than-Truckload Vehicle System
Abstract:
In cooperative logistics, shippers can cooperate to improve efficiency and reduce the cost of product/package delivery services. In this paper, we consider the resource, i.e., vehicles, sharing problem to serve customers in the cooperative logistics environment. In the environment, small shippers cooperate by forming a coalition to create a vehicle pool and to allow sharing of their own vehicles with each other. The vehicles in the pool are used to deliver packages to customers. To minimize the delivery cost to the shippers, we propose a framework for the capacitated vehicle routing problem with time windows. The framework is composed of joint vehicle allocation, cost management, and overlapping coalition formation among shippers. For vehicle allocation, we formulate and solve optimization models to determine the number of vehicles and their delivery routes to meet customer demand and service time. The uncertainty of customer demand is taken into consideration. For sharing the delivery cost generated in the vehicle pool, i.e., cost management, among the cooperative shippers in a coalition, we apply the concept of Myerson value from the cooperative game theory as a solution. Based on the cost, the shippers then decide whether to cooperate and share the vehicles or not. The performance evaluation based on the test and actual road networks clearly shows the benefits of the proposed framework.
Autors: Rakpong Kaewpuang;Dusit Niyato;Puay-Siew Tan;Ping Wang;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 5707 - 5722
Publisher: IEEE
 
» Cooperative Relaying Using Space-Time Block Coded Non-orthogonal Multiple Access
Abstract:
Non-orthogonal multiple access (NOMA) has attracted significant attention in the research community as a potential radio access technology for future wireless networks. In this work, we propose a two-phase cooperative decode-and-forward (DF) relaying scheme based on Alamouti (2  1 multiple-input single-output mode) space-time block-coded non-orthogonal multiple access (STBC-NOMA). Closed-form solutions for ergodic sum capacity and outage probability of the proposed scheme are analyzed over independent Rayleigh fading channels. Asymptotic approximations for ergodic sum capacity, outage probability, and outage sum capacity at the high signal-to-noise ratio regime are also provided. It has been pointed out that the proposed cooperative relaying system (CRS) using STBC-NOMA can attain significant performance gains compared to the conventional CRS using NOMA and the traditional DF relaying schemes. It is also demonstrated that the relay position between the transmitter and the receiver has a significant impact on the performance of the proposed protocol. In addition, the proximity between analytical and simulation results confirms the efficiency of the proposed protocol.
Autors: Md. Fazlul Kader;Soo Young Shin;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 5894 - 5903
Publisher: IEEE
 
» Cooperative Stabilization of a Class of LTI Plants With Distributed Observers
Abstract:
Over the last decades, the cooperative design of complex networked systems has received an increasing attention in real-world engineering practices. Traditionally, each node in the network is assumed to obtain the same signal. However, each agent often possesses different measurement due to the observability or configuration of the systems. To solve the stabilization problem in this case, we aim to establish a unified framework for the cooperative control of complex network with distributed observers. In detail, different from the traditional centralized design, this paper initiates a cooperative approach by only using the local information of the networked systems. In allusion to the three kinds of representative networks, this paper establishes some sufficient or necessary conditions for the existence of network parameters that guarantee the stabilization of the LTI plants. Moreover, some corresponding algorithms are developed to find the suitable parameters of networked observers. Last but not least, numerical simulations are also provided to verify the above theoretical results.
Autors: Kexin Liu;Henghui Zhu;Jinhu Lü;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2017, volume: 64, issue:7, pages: 1891 - 1902
Publisher: IEEE
 
» Coordinated Multicell Multicast Beamforming Based on Manifold Optimization
Abstract:
Multicast beamforming is a key technology for next-generation wireless cellular networks to support high-rate content distribution services. In this letter, the coordinated downlink multicast beamforming design in multicell networks is considered. The goal is to maximize the minimum signal-to-interference-plus-noise ratio of all users under individual base station power constraints. We exploit the fractional form of the objective function and geometric properties of the constraints to reformulate the problem as a parametric manifold optimization program. Afterwards we propose a low-complexity Dinkelbach-type algorithm combined with adaptive exponential smoothing and Riemannian conjugate gradient iteration, which is guaranteed to converge. Numerical experiments show that the proposed algorithm outperforms the existing SDP-based method and DC-programming-based method and achieves near-optimal performance.
Autors: Longfei Zhou;Le Zheng;Xiaodong Wang;Wei Jiang;Wu Luo;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1673 - 1676
Publisher: IEEE
 
» Coordinated Power Control of Variable-Speed Diesel Generators and Lithium-Battery on a Hybrid Electric Boat
Abstract:
This paper presents coordinated power management strategies for a hybrid electric boat (HEB) based on dynamic load's power distribution approach using diesel generators and batteries. Two variable-speed diesel generator sets connecting to dc-bus via fully controlled rectifiers serve as the main power supply source; one lithium-battery pack linked to dc-bus through a bidirectional DC/DC converter serves as an auxiliary power supply source. The power requirement of the thrusters and other onboard equipment is represented by a load power profile. The main contribution of this paper is focused on the load power sharing of the HEB between the two variable-speed diesel generators and the lithium-battery pack, through the fluctuations extracted from load power and their assignation to the batteries. Another important issue is that when the total load demand is low, one of the diesel generator set will be switched off to improve the diesel-fuel efficiency. The output powers of the diesel generators and the batteries are controlled based on the power distribution strategy via the converters controlling. The performances of the proposed hybrid power system control are evaluated through simulations in MATALB/Simulink, and through reduced-scale experimental tests carried out for a specific driving cycle of the HEB.
Autors: Zhibin Zhou;Mamadou Baïlo Camara;Brayima Dakyo;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 5775 - 5784
Publisher: IEEE
 
» Coregistration of Interferometric Stacks of Sentinel-1 TOPS Data
Abstract:
The coregistration of synthetic aperture radar images is of fundamental importance for the generation of interferograms. The high azimuth coregistration requirements imposed by the TOPS acquisition mode imply that an advanced approach for the coregistration of stacked time series images is needed due to temporal decorrelation effects. In some scenarios, the conventional approach of estimating the shifts pairwise with respect to the same master might result insufficient. Therefore, a joint estimation is proposed here, which exploits jointly all interferograms in order to retrieve more accurate results. Simulated data and Sentinel-1A images acquired in IW mode are used to validate this procedure, demonstrating the better performance of the joint approach when compared to the standard single-master approach.
Autors: Nestor Yague-Martinez;Francesco De Zan;Pau Prats-Iraola;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jul 2017, volume: 14, issue:7, pages: 1002 - 1006
Publisher: IEEE
 
» Corrections to "Efficient Adaptive Turbo Equalization for Multiple-Input–Multiple-Output Underwater Acoustic Communications" [W. Duan, J. Tao, and Y. Rosa Zheng, IEEE J. Ocean. Eng ., 2017, DOI: 10.1109/JOE.2017.2707285]
Abstract:
Equation In [1], (6) of the above named work is corrected.
Autors: W. Duan;J. Tao;Y. R. Zheng;
Appeared in: IEEE Journal of Oceanic Engineering
Publication date: Jul 2017, volume: 42, issue:3, pages: 752 - 752
Publisher: IEEE
 
» Corrections to “Optical Characterization of Chalcogenide Ge–Sb–Se Waveguides at Telecom Wavelengths”
Abstract:
The original letter [1] contains an error in the two-photon absorption coefficient of the chalcogenide waveguides. The fitting equation (1) used in [1] was incorrect, leading to an overestimation of the two-photon absorption.
Autors: Molly R. Krogstad;Sungmo Ahn;Wounjhang Park;Juliet T. Gopinath;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jul 2017, volume: 29, issue:14, pages: 1219 - 1220
Publisher: IEEE
 
» Correlation Tests and Linear Spectral Statistics of the Sample Correlation Matrix
Abstract:
Testing the independence of the entries of multidimensional Gaussian observations is a very important problem in statistics, with a number of applications in signal processing, radar, cognitive radio, seismography, and multiple other fields. Typically, the problem is formulated as a binary hypothesis test, whereby the presence of correlation is declared when the value of a certain statistic is higher than a certain predetermined threshold. Most of the statistics for correlation tests are constructed from the sample correlation matrix (also known as sample coherence matrix in signal processing), which is defined as a power-normalized version of the sample covariance matrix. In this paper, correlation tests constructed from linear spectral statistics (LSS) of the sample correlation matrix are analyzed under the asymptotic framework where both sample size and observation dimension become large but comparable in magnitude. A central limit theorem (CLT) is established on this class of statistics, which is valid for generally correlated Gaussian observations. Results show that LSS asymptotically fluctuate as Gaussian random variables under both the hypotheses, with an asymptotic mean and variance that can be established for each particular test. In particular, this general CLT can be used to establish the asymptotic behavior of two of the most important correlation test statistics, namely the generalized likelihood ratio test and the Frobenius norm test, under both null and alternative hypotheses. As a by-product, it is established that LSS of sample covariance and sample correlation matrices have exactly the same first order behavior, but quite different asymptotic fluctuations in the second-order regime. In both the cases, the LSS asymptotically behave as Gaussian random variables, although with quite different asymptotic means and variances.
Autors: Xavier Mestre;Pascal Vallet;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4585 - 4618
Publisher: IEEE
 
» Cost-Aware Region-Level Data Placement in Multi-Tiered Parallel I/O Systems
Abstract:
Multi-tiered Parallel I/O systems that combine traditional HDDs with emerging SSDs mitigate the cost burden of SSDs while benefiting from their superior I/O performance. While a multi-tiered parallel I/O system is promising for data-intensive applications in high-performance (HPC) domains, placing data on each tier of the system to achieve high I/O performance remains a challenge. In this paper, we propose a cost-aware region-level (CARL) data placement scheme in multi-tiered parallel I/O systems. CARL divides a large file into several small regions, and then places regions on different types of servers based on region access costs. CARL includes a static policy S-CARL and a dynamic policy D-CARL. For applications whose I/O access patterns are completely known, S-CARL calculates the region costs within the entire workload duration, and uses a static data placement scheme to selectively place regions on the proper servers. To adapt to applications whose access patterns are unknown in advance, D-CARL uses a dynamic data placement scheme which migrates data among different servers within each time window. We have implemented CARL under MPI-IO library and OrangeFS parallel file system environment. Our evaluation with representative benchmarks and an application shows that CARL is both feasible and able to improve I/O performance significantly.
Autors: Shuibing He;Yang Wang;Zheng Li;Xian-He Sun;Chenzhong Xu;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jul 2017, volume: 28, issue:7, pages: 1853 - 1865
Publisher: IEEE
 
» Cost-Constrained Viterbi Algorithm For Resource Allocation in Solar Base Stations
Abstract:
Solar energy is currently a popular renewable resource, yet limited daily. In green cellular networks, multiple constraints optimization (MCO) problems arise naturally. For example, a typical objective is to control the power transmission of the hybrid base stations (BSs) (connected to both solar panels and electrical grid) in order to maximize user’s average throughput, under the constraints of consumed grid energy and user’s blocking rate. However, such problems have been generally proved to be NP-hard. In this paper, we formulate this generic MCO problem as a quantized Markovian cost-reward model, with no assumption on input data. We then propose a novel algorithm, namely cost-constrained Viterbi algorithm, which recursively returns the optimal policy with linear computational complexity for this model. As an application, we provide engineering rules for the design of hybrid BSs through extensive simulations. In comparison with brute force method for a simple scenario, we find that our algorithm does achieve the constrained optimal policy.
Autors: Viet Hung Tran;Marceau Coupechoux;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4166 - 4180
Publisher: IEEE
 
» Cost-Effective Grid-Connected Inverter for a Micro Combined Heat and Power System
Abstract:
This paper proposes a novel, cost-effective grid-connected inverter for a domestic micro combined heat and power system. A high-frequency (∼12 000 r/min), high-voltage (∼425 Vdc) brushless dc machine is used as the generator. The output of the generator is injected into the grid through a novel grid-connected inverter, utilizing a digital algorithm for the implementation of a constant frequency hysteresis current control. This allows a simplified output filter with smaller components to be employed. A grid synchronization method has also been designed, based on a low-pass filter and a microcontroller to optimize/tune the output power factor. The proposed method is successfully applied to a 500-W, 230-V, 50-Hz grid-connected voltage-source inverter (VSI) prototype, where the output of the VSI has been demonstrated to comply with the operating regulations for domestic distributed power generation systems.
Autors: Ruoyang Du;Paul Robertson;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5360 - 5367
Publisher: IEEE
 
» Cost-Efficient Resource Allocation in Cloud Radio Access Networks With Heterogeneous Fronthaul Expenditures
Abstract:
As an advanced paradigm, the cloud radio access network (C-RAN) promises high spectral efficiency (SE) and energy efficiency (EE). However, the capacity-constrained front-haul has become a key performance bottleneck in C-RANs. Besides SE and EE metrics, the cost related to different kinds of fronthaul is another major concern for operators. In this paper, an economical SE (ESE) metric is proposed to jointly take traditional EE and the impact of wired/wireless fronthaul cost into account. Aiming to maximize ESE, a non-convex beamformer design problem with fronthaul capacity and transmit power constraints is formulated, and an algorithm containing outer and inner loops is proposed to deal with this non-convexity. In particular, in the outer loop, the bisection search method is adopted to transform the primal problem into an equivalent subproblem; while in the inner loop, owing to the equivalence between the subproblem and the weighted sum rate, the subproblem is solved by the weighted minimum mean square error approach. Simulation results demonstrate that the proposed ESE is more reasonable than SE and EE for the fronthaul-constrained C-RAN. Furthermore, the proposed optimization solution can significantly improve ESE, in which the impact of fronthaul cost on ESE is evaluated.
Autors: Mugen Peng;Yayun Wang;Tian Dang;Zhipeng Yan;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4626 - 4638
Publisher: IEEE
 
» Coverage Analysis for Millimeter Wave Networks: The Impact of Directional Antenna Arrays
Abstract:
Millimeter wave (mm-wave) communications is considered a promising technology for 5G networks. Exploiting beamforming gains with large-scale antenna arrays to combat the increased path loss at mm-wave bands is one of the defining features. However, previous works on mm-wave network analysis usually adopted oversimplified antenna patterns for tractability, which can lead to significant deviation from the performance with actual antenna patterns. In this paper, using tools from stochastic geometry, we carry out a comprehensive investigation on the impact of directional antenna arrays in mm-wave networks. We first present a general and tractable framework for coverage analysis with arbitrary distributions for interference power and arbitrary antenna patterns. It is then applied to mm-wave ad hoc and cellular networks, where two sophisticated antenna patterns with desirable accuracy and analytical tractability are proposed to approximate the actual antenna pattern. Compared with previous works, the proposed approximate antenna patterns help to obtain more insights on the role of directional antenna arrays in mm-wave networks. In particular, it is shown that the coverage probabilities of both types of networks increase as a non-decreasing concave function with the antenna array size. The analytical results are verified to be effective and reliable through simulations, and numerical results also show that large-scale antenna arrays are required for satisfactory coverage in mm-wave networks.
Autors: Xianghao Yu;Jun Zhang;Martin Haenggi;Khaled B. Letaief;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: Jul 2017, volume: 35, issue:7, pages: 1498 - 1512
Publisher: IEEE
 
» CP-FPGA: Energy-Efficient Nonvolatile FPGA With Offline/Online Checkpointing Optimization
Abstract:
Field-programmable gate arrays (FPGAs) have drawn lots of attentions due to their programmability and high performance. Recently, ultralow-power FPGAs for Internet of Things, together with energy-harvesting technique, have become an emerging self-powered computing platform. However, volatile memory in FPGA will lose their states under unstable power supplies and cannot work efficiently. Nonvolatile FPGA becomes a promising alternative. This paper proposes a hardware/software codesign nonvolatile FPGA with efficient offline/online checkpointing strategy (CP-FPGA). Backup energy is reduced by offline selecting proper checkpointing locations to minimize backup data. An online scheduler is further proposed to balance computation rollback overhead against backup energy. Experimental results show that the proposed CP-FPGA reduces 39.5% energy consumption on average compared with the state-of-the-art techniques.
Autors: Zhe Yuan;Yongpan Liu;Jinyang Li;Jingtong Hu;Chun Jason Xue;Huazhong Yang;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jul 2017, volume: 25, issue:7, pages: 2153 - 2163
Publisher: IEEE
 
» CRB-RPL: A Receiver-Based Routing Protocol for Communications in Cognitive Radio Enabled Smart Grid
Abstract:
As a tool for overcoming radio spectrum shortages in wireless communications, cognitive radio technology plays a vital role in future smart grid applications, particularly in advanced metering infrastructure (AMI) networks with quality of service (QoS) requirements. This paper focuses on the investigation of the receiver-based routing protocol for enhancing QoS in cognitive radio-enabled AMI networks, due to their potentials of enhancing reliability and routing efficiency. In accordance with practical requirements of smart grid applications, a new routing protocol with two purposes is proposed: One is to address the real-time requirement while another protocol focuses on how to meet energy efficiency requirements. As a special feature of cognitive radio technology, the protocol has the mechanism for protecting primary (licensed) users while meeting the utility requirements of secondary (cognitive radio) users. System-level evaluation shows that the proposed routing protocol can achieve better performances compared with existing routing protocols for cognitive radio-enabled AMI networks.
Autors: Zhutian Yang;Shuyu Ping;Hongjian Sun;Abdol-Hamid Aghvami;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 5985 - 5994
Publisher: IEEE
 
» Cross-Layer Resource Allocation for Scalable Video Over OFDMA Wireless Networks: Tradeoff Between Quality Fairness and Efficiency
Abstract:
This work addresses the tradeoff between quality fairness and system efficiency for scalable video delivery to multiple users over OFDMA wireless networks. We consider a cross-layer optimization framework seeking to maximize the sum-PSNR corresponding to average user rates, subject to relaxed PSNR-fair constraints. More specifically, a pure quality-fairness (PF) problem is solved first to determine the maximum PSNR value obtained by imposing the same PSNR level to all users. Next the constraints in the PF problem are relaxed by allowing the relative difference between the PSNR of each video and the PF PSNR value to be within some range . Thus, the parameter controls the tradeoff between quality fairness and system efficiency. The PF problem is equivalent to the quality fairness problem proposed by Cicalò and Tralli, which was solved using a vertical decomposition approach. Further, we convert the optimization problem with the relaxed fairness constraints into a convex problem and solve it using established techniques. Our simulation results show that by varying the value of , a wide range, densely populated, of trade-off points between quality fairness and efficiency can be achieved. Additionally, a subjective quality assessment reveals that while the maximum efficiency scheme (ME), i.e., when , may compromise the quality of the high demanding videos, the PF scheme may sacrifice the quality of the low demanding videos. On the other hand, by providing a trade-off between PF and ME, the proposed scheme has the potential of finding a middle ground where all users are satisfied.
Autors: Kuan Lin;Sorina Dumitrescu;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jul 2017, volume: 19, issue:7, pages: 1654 - 1669
Publisher: IEEE
 
» Crowdsourced Coverage as a Service: Two-Level Composition of Sensor Cloud Services
Abstract:
We present a new two-level composition model for crowdsourced Sensor-Cloud services based on dynamic features such as spatio-temporal aspects. The proposed approach is defined based on a formal Sensor-Cloud service model that abstracts the functionality and non-functional aspects of sensor data on the cloud in terms of spatio-temporal features. A spatio-temporal indexing technique based on the 3D R-tree to enable fast identification of appropriate Sensor-Cloud services is proposed. A novel quality model is introduced that considers dynamic features of sensors to select and compose Sensor-Cloud services. The quality model defines Coverage as a Service which is formulated as a composition of crowdsourced Sensor-Cloud services. We present two new QoS-aware spatio-temporal composition algorithms to select the optimal composition plan. Experimental results validate the performance of the proposed algorithms.
Autors: Azadeh Ghari Neiat;Athman Bouguettaya;Timos Sellis;Sajib Mistry;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jul 2017, volume: 29, issue:7, pages: 1384 - 1397
Publisher: IEEE
 
» Cryptanalysis of Controlled Bidirectional Quantum Secure Direct Communication Network Using Classical XOR Operation and Quantum Entanglement
Abstract:
In a recent letter, a controlled bidirectional quantum secure direct communication protocol with cluster states was proposed. We analyzed the security of this protocol and found that it is insecure. In the original protocol, a dishonest controller can eavesdrop the secret messages exchanged between the users, and a dishonest user may achieve his communication goal without the permission of the controller. The corresponding two kinds of attack strategies are presented. Finally, we give a feasible improvement of this communication protocol.
Autors: Song Lin;Wenjie Liu;Gongde Guo;Binbin Cai;Xiaofen Liu;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1561 - 1564
Publisher: IEEE
 
» CSI-EPT in Presence of RF-Shield for MR-Coils
Abstract:
Contrast source inversion electric properties tomography (CSI-EPT) is a recently developed technique for the electric properties tomography that recovers the electric properties distribution starting from measurements performed by magnetic resonance imaging scanners. This method is an optimal control approach based on the contrast source inversion technique, which distinguishes itself from other electric properties tomography techniques for its capability to recover also the local specific absorption rate distribution, essential for online dosimetry. Up to now, CSI-EPT has only been described in terms of integral equations, limiting its applicability to homogeneous unbounded background. In order to extend the method to the presence of a shield in the domain—as in the recurring case of shielded radio frequency coils—a more general formulation of CSI-EPT, based on a functional viewpoint, is introduced here. Two different implementations of CSI-EPT are proposed for a 2-D transverse magnetic model problem, one dealing with an unbounded domain and one considering the presence of a perfectly conductive shield. The two implementations are applied on the same virtual measurements obtained by numerically simulating a shielded radio frequency coil. The results are compared in terms of both electric properties recovery and local specific absorption rate estimate, in order to investigate the requirement of an accurate modeling of the underlying physical problem.
Autors: Alessandro Arduino;Luca Zilberti;Mario Chiampi;Oriano Bottauscio;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jul 2017, volume: 36, issue:7, pages: 1396 - 1404
Publisher: IEEE
 
» CSI7: A Modified Three-Phase Current-Source Inverter for Modular Photovoltaic Applications
Abstract:
This paper analyzes the performance of a grid-tied, wide power range, transformerless, modified three-phase current-source inverter (CSI), named CSI7. The CSI7 topology is here analyzed along with a suitable space vector modulation strategy able to attenuate the excitation of the output CL filter. The theoretical analysis and simple analytic expressions highlighted the performance and limitations of the topology when employed as a single-stage photovoltaic (PV) inverter, with a particular emphasis on injected grid current distortion and ground leakage current values. The inverter wide input range allows interfacing PV strings of different module count with a simple closed-loop control. The principle of operation and control is described; the viability of the CSI7 topology was assessed with simulations and extensive experiments on a full-size laboratory prototype.
Autors: Emilio Lorenzani;Fabio Immovilli;Giovanni Migliazza;Matteo Frigieri;Claudio Bianchini;Matteo Davoli;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5449 - 5459
Publisher: IEEE
 
» Current Control of Grid-Connected Inverter With LCL Filter Based on Extended-State Observer Estimations Using Single Sensor and Achieving Improved Robust Observation Dynamics
Abstract:
In the context of distributed generation and renewable energy penetration toward smart grid, grid-connected inverter with LCL filter has drawn many attentions, whose current control conventionally requires several sensors to realize active damping and grid synchronization. In this paper, a novel full status observation strategy based on extended state observer (ESO) is proposed using inverter current feedback only and without grid voltage sensor. The proposed observation strategy contains observation and transformation process. Unlike conventional Luenberger observer, by using ESO, the system parameters do not appear in observation process, thus the observer dynamics and parameter mismatch error can be separately handled, providing more robust observation dynamics during parameter variation. Parameter mismatch study was carried out, and it is found that purposely choosing the observer parameters smaller than the real value can achieve relatively low estimation error and a large adaption range for parameter variation. The proposed observation strategy is simple to implement, without the need of expert knowledge-based parameter tuning such as pole placement. Experimental tests validated that the proposed observation-based control is able to give satisfactory performance in both dynamic and steady states, as well as adaption for system parameter variation.
Autors: Baochao Wang;Yongxiang Xu;Zhaoyuan Shen;Jibin Zou;Chaoquan Li;Hong Liu;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5428 - 5439
Publisher: IEEE
 
» Current Status of Korea Heat Load Test Facility KoHLT-EB for Fusion Reactor Materials
Abstract:
The Korea heat load test facility using electron beam (KoHLT-EB) was constructed and commissioned to perform high heat flux testing on plasma facing components (PFCs), such as ITER blanket first wall, the tungsten divertor, and heat transfer experiments on other cooling devices. Also it will be used for the thermo-hydraulic performance test of ITER helium cooled ceramic reflector test blanket module in Korea. Qualification tests will be performed to evaluate the use of the high heat flux test facility on PFC and fusion reactor materials. For the thermal fatigue test of PFCs, two types of tungsten mockups were fabricated. One is a coated tungsten on the ferritic–martensitic steel (FMS). The other is a hot isostatic pressing bonded tungsten with FMS. Also, the integrity and cooling performance should be tested under the same or similar operation conditions of the ITER PFCs. After the completion of the preliminary mockup test and the facility qualification, the high heat flux test facility, KoHLT-EB, will provide the performance test for the various PFCs in fusion reactor materials and PFCs.
Autors: Suk-Kwon Kim;Seong Dae Park;Hyoung Gon Jin;Eo Hwak Lee;Jae-Sung Yoon;Dong Won Lee;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jul 2017, volume: 45, issue:7, pages: 1820 - 1823
Publisher: IEEE
 
» Current-Limiting Droop Control of Grid-Connected Inverters
Abstract:
A current-limiting droop controller is proposed for single-phase grid-connected inverters with an LCL filter that can operate under both normal and faulty grid conditions. The controller introduces bounded nonlinear dynamics and, by using nonlinear input-to-state stability theory, the current-limiting property of the inverter is analytically proven. The proposed controller can be operated in the set mode to accurately send the desired power to the grid or in the droop mode to take part in the grid regulation, while maintaining the inverter current below a given value at all times. Opposed to the existing current-limiting approaches, the current limitation is achieved without external limiters, additional switches, or monitoring devices and the controller remains a continuous-time system guaranteeing system stability. Furthermore, this is achieved independently from grid voltage and frequency variations, maintaining the desired control performance under grid faults as well. Extensive experimental results are presented to verify the droop function of the proposed controller and its current-limiting capability under normal and faulty grid conditions.
Autors: Qing-Chang Zhong;George C. Konstantopoulos;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5963 - 5973
Publisher: IEEE
 
» Cyber-Physical Attack-Resilient Wide-Area Monitoring, Protection, and Control for the Power Grid
Abstract:
Cybersecurity and resiliency of wide-area monitoring, protection, and control (WAMPAC) applications is critically important to ensure secure, reliable, and economical operation of the bulk power system. WAMPAC relies heavily on the security of measurements and control commands transmitted over wide-area communication networks for real-time operational, protection, and control functions. The current “N–1” security criterion for grid operation is inadequate to address malicious cyber events; therefore, it is important to fundamentally redesign WAMPAC and to enhance energy management system applications to make them attack resilient. In this paper, we present three key contributions to enhance the cybersecurity and resiliency of WAMPAC. First, we describe an end-to-end attack-resilient cyber–physical security framework for WAMPAC applications encompassing the entire security life cycle including risk assessment, attack prevention, attack detection, attack mitigation, and attack resilience. Second, we describe a defense-in-depth architecture that incorporates attack resilience at both the infrastructure layer and the application layer by leveraging domain-specific security approaches at the WAMPAC application layer in addition to traditional cybersecurity measures at the information technology infrastructure layer. Third, we discuss several attack-resilient algorithms for WAMPAC that leverage measurement design and cyber–physical system model-based anomaly detection and mitigation along with illustrative case studies. We believe that the research issues and solutions identified in this paper will open up several avenues for research in this area. In particular, the proposed framework, architectural concepts, and attack-resilient algorithms would serve as essential building blocks to transform the “fault-resilient” grid of toda- into an “attack-resilient” grid of the future.
Autors: Aditya Ashok;Manimaran Govindarasu;Jianhui Wang;
Appeared in: Proceedings of the IEEE
Publication date: Jul 2017, volume: 105, issue:7, pages: 1389 - 1407
Publisher: IEEE
 
» Cybersecurity in Distributed Power Systems
Abstract:
This paper presents the application of cybersecurity to the operation and control of distributed electric power systems. In particular, the paper emphasizes the role of cybersecurity in the operation of microgrids and analyzes the dependencies of microgrid control and operation on information and communication technologies for cybersecurity. The paper discusses common cyber vulnerabilities in distributed electric power systems and presents the implications of cyber incidents on physical processes in microgrids. The paper examines the impacts of potential risks attributed to cyberattacks on microgrids and presents the affordable technologies for mitigating such risks. In addition, the paper presents a minimax-regret approach for minimizing the impending risks in managing microgrids. The paper also presents the opportunities provided by software-defined networking technologies to enhance the security of microgrid operations. It is concluded that cybersecurity could play a significant role in managing microgrid operations as microgrids strive for a higher degree of resilience as they supply power services to customers.
Autors: Zhiyi Li;Mohammad Shahidehpour;Farrokh Aminifar;
Appeared in: Proceedings of the IEEE
Publication date: Jul 2017, volume: 105, issue:7, pages: 1367 - 1388
Publisher: IEEE
 
» D–Q Impedance Based Stability Analysis and Parameter Design of Three-Phase Inverter-Based AC Power Systems
Abstract:
Small-signal stability is an important concern in three-phase inverter-based ac power systems. The impedance-based approach based on the generalized Nyquist stability criterion (GNC) can analyze the stability related with the medium and high-frequency modes of the systems. However,. the GNC involves the right-half-plane (RHP) pole calculation of return-ratio transfer function matrices, which cannot be avoided for stability analysis of complicated ac power systems. Therefore, it necessitates the detailed internal control information of the inverters, which is not normally available for commercial inverters. To address this issue, this paper introduces the component connection method (CCM) in the frequency domain for stability analysis in the synchronous d–q frame, by proposing a method of deriving the impedance matrix of the connection networks of inverter-based ac power systems. Demonstration on a two-area system and a microgrid shows that: The CCM-enabled approach can avoid the RHP pole calculation of return-ratio matrices and enables the stability analysis by using only the impedances of system components, which could be measured without the need for the internal information. A stability analysis method based on d–q impedances, the CCM, and the determinant-based GNC is also proposed to further simplify the analysis process. Inverter controller parameters can be designed as stability regions in parameter spaces, by repetitively applying the proposed stability analysis method. Simulation and experimental results verify the validity of the proposed stability analysis method and the parameter design approach.
Autors: Wenchao Cao;Yiwei Ma;Liu Yang;Fei Wang;Leon M. Tolbert;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 6017 - 6028
Publisher: IEEE
 
» Data Compression With Low Distortion and Finite Blocklength
Abstract:
This paper considers lossy source coding of -dimensional memoryless sources and shows an explicit approximation to the minimum source coding rate required to sustain the probability of exceeding distortion no greater than , which is simpler than known dispersion-based approximations. Our approach takes inspiration in the celebrated classical result stating that the Shannon lower bound to rate-distortion function becomes tight in the limit . We formulate an abstract version of the Shannon lower bound that recovers both the classical Shannon lower bound and the rate-distortion function itself as special cases. Likewise, we show that a nonasymptotic version of the abstract Shannon lower bound recovers all previously known nonasymptotic converses. A necessary and sufficient condition for the Shannon lower bound to be attained exactly is presented. It is demonstrated that whenever that condition is met, the rate-dispersion function is given simply by the varentropy of the source. Remarkably, all finite alphabet sources with balanced distortion measures satisfy that condition in the range of low distortions. Most continuous sources violate that condition. Still, we show that lattice quantizers closely approach the nonasymptotic Shannon lower bound, provided that the source density is smooth enough and the distortion is low. This implies that fine multidimensional lattice coverings are nearly optimal in the rate-distortion sense even at finite . The achievability proof technique is based on a new bound on the output entropy of lattice quantizers in terms of the differential entropy - f the source, the lattice cell size, and a smoothness parameter of the source density. The technique avoids both the usual random coding argument and the simplifying assumption of the presence of a dither signal.
Autors: Victoria Kostina;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4268 - 4285
Publisher: IEEE
 
» Data-Based Tuning of Reduced-Order Inverse Model in Both Disturbance Observer and Feedforward With Application to Tray Indexing
Abstract:
Performance of traditional model-based control relies upon accurate modeling. In motion control of flexible systems, it is desirable to use the reduced-order model for ease of trajectory planning and pole placement, but its performance is constrained by modeling inaccuracies due to the existence of friction and multiple flexible modes. To improve the tracking performance, we have developed a data-based method for iterative tuning of the parameters in the reduced-order inverse model within a three-degree-of-freedom composite control structure. The proposed method solely makes use of the input-output data obtained during closed-loop experiments to fine-tune the inverse system model, and accurate system modeling is not required. Unbiasedness of the cost function gradient estimation is proven under reasonable assumptions of stochastic properties of the perturbations. Simulation and experiments are conducted to further illustrate the proposed method and show its practical appeals in industrial applications.
Autors: Xiaocong Li;Si-Lu Chen;Chek Sing Teo;Kok Kiong Tan;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5492 - 5501
Publisher: IEEE
 
» DCT-OFDM With Index Modulation
Abstract:
In this letter, index modulation (IM) is proposed for OFDM systems based on a discrete cosine transform (DCT) implementation. The new DCT-OFDM-IM scheme is shown to yield spectral efficiency improvements of up to 38% relative to OFDM-IM and up to 55% relative to OFDM while occupying the same bandwidth and maintaining similar robustness against the frequency selective fading channels for low modulation orders.
Autors: Marwa Chafii;Justin P. Coon;Dene A. Hedges;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1489 - 1492
Publisher: IEEE
 
» Deadbeat Control Based on Current Predictive Calibration for Grid-Connected Converter Under Unbalanced Grid Voltage
Abstract:
Deadbeat control (DBC) is developed based on the system model, which is commonly used to achieve good control performance for a three-phase grid connected converter (GCC). Unbalanced grid voltage is a common phenomenon in power systems. In this study, an improved DBC based on current predictive correction (CPC_DBC) is used to control GCC under an unbalanced grid voltage. The main purposes of CPC_DBC are to reduce the adverse effects due to random sampling error to improve current control performance, and to enhance the interference rejection capability of the control system. Then, the characteristics of CPC_DBC and the conventional DBC (Con_DBC) are analyzed by transfer functions in the discrete time domain. Several common control objectives under an unbalanced grid voltage are used to demonstrate the superiority of CPC_DBC. Finally, the experimental results indicate that CPC_DBC can effectively reduce the adverse effects of random sampling error; the robustness of system due to the uncertain value of the filter inductance is improved as well.
Autors: Weidong Jiang;Weicheng Ma;Jinping Wang;Lei Wang;Yan Gao;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5479 - 5491
Publisher: IEEE
 
» Decentralized Reactive Power Sharing and Frequency Restoration in Islanded Microgrid
Abstract:
P-f and Q-V droop methods are the most common decentralized control methods in islanded microgrid. Although with the P-f droop method, an accurate active power sharing can be achieved among distributed energy resources (DERs), by Q-V droop, the reactive power sharing among DERs often deteriorates due to its highly dependence on the power line impedances and the local load. Variation of frequency and voltage by load changes is another challenge in droop control method. In this paper, a new autonomous control method is proposed to share reactive power among DERs accurately and restore frequency of a microgrid. The proposed method does not require any communication link and so maintains reliability and simplicity of the network. The synchronizing among DERs is obtained by the load change detection, which is accomplished by wavelet transform. The method operation principle is explained and analyzed. Simulation results are presented to validate the effectiveness of the proposed method.
Autors: Mojtaba Kosari;Seyed Hossein Hosseinian;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 2901 - 2912
Publisher: IEEE
 
» Decoupling Network of Field-Oriented Control in Variable-Frequency Drives
Abstract:
A synchronous current controller for field-oriented control is a popular control scheme that is used in industry to separately control the synchronous current of an induction motor in steady state. However, in some transient states such as during start-up and variation of the mechanical load, the synchronous current along the d -axis remains coupled to the q-axis current. Conventional decoupling current control considers only the model of an induction motor to compensate these coupling terms, but the motor is often powered by an inverter, which also influences the current, voltage, and torque behavior. Thus, a novel decoupling current control method is proposed to consider the coupling terms of both the motor and power converter in a synchronous current controller. Existing approaches assume that the motor is directly connected to the power supply, so a model is also suggested for a pulse width modulation (PWM) inverter. Analytical equations with simulation and experimental results prove that the coupling terms are still present when not considering the PWM inverter in the decoupling network. The proposed method shows good performance, and the d-axis current is always separated from the q-axis current during variation of the mechanical load.
Autors: Daniel Legrand Mon-Nzongo;Tao Jin;Gabriel Ekemb;Laurent Bitjoka;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5746 - 5750
Publisher: IEEE
 
» Deep Convolutional Highway Unit Network for SAR Target Classification With Limited Labeled Training Data
Abstract:
The deep convolutional neural network (CNN) has been widely used for target classification, because it can learn highly useful representations from data. However, it is difficult to apply a CNN for synthetic aperture radar (SAR) target classification directly, for it often requires a large volume of labeled training data, which is impractical for SAR applications. The highway network is a newly proposed architecture based on CNN that can be trained with smaller data sets. This letter proposes a novel architecture called the convolutional highway unit to train deeper networks with limited SAR data. The unit architecture is formed by modified convolutional highway layers, a maxpool layer, and a dropout layer. Then, the networks can be flexibly formed by stacking the unit architecture to extract deep feature representations for classification. Experimental results on the moving and stationary target acquisition and recognition data set indicate that the branched ensemble model based on the unit architecture can achieve 99% classification accuracy with all training data. When the training data are reduced to 30%, the classification accuracy of the ensemble model can still reach 94.97%.
Autors: Zhao Lin;Kefeng Ji;Miao Kang;Xiangguang Leng;Huanxin Zou;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jul 2017, volume: 14, issue:7, pages: 1091 - 1095
Publisher: IEEE
 
» Deep Learning Segmentation of Optical Microscopy Images Improves 3-D Neuron Reconstruction
Abstract:
Digital reconstruction, or tracing, of 3-D neuron structure from microscopy images is a critical step toward reversing engineering the wiring and anatomy of a brain. Despite a number of prior attempts, this task remains very challenging, especially when images are contaminated by noises or have discontinued segments of neurite patterns. An approach for addressing such problems is to identify the locations of neuronal voxels using image segmentation methods, prior to applying tracing or reconstruction techniques. This preprocessing step is expected to remove noises in the data, thereby leading to improved reconstruction results. In this paper, we proposed to use 3-D convolutional neural networks (CNNs) for segmenting the neuronal microscopy images. Specifically, we designed a novel CNN architecture, that takes volumetric images as the inputs and their voxel-wise segmentation maps as the outputs. The developed architecture allows us to train and predict using large microscopy images in an end-to-end manner. We evaluated the performance of our model on a variety of challenging 3-D microscopy images from different organisms. Results showed that the proposed methods improved the tracing performance significantly when combined with different reconstruction algorithms.
Autors: Rongjian Li;Tao Zeng;Hanchuan Peng;Shuiwang Ji;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jul 2017, volume: 36, issue:7, pages: 1533 - 1541
Publisher: IEEE
 
» Deep Recurrent Neural Networks for Hyperspectral Image Classification
Abstract:
In recent years, vector-based machine learning algorithms, such as random forests, support vector machines, and 1-D convolutional neural networks, have shown promising results in hyperspectral image classification. Such methodologies, nevertheless, can lead to information loss in representing hyperspectral pixels, which intrinsically have a sequence-based data structure. A recurrent neural network (RNN), an important branch of the deep learning family, is mainly designed to handle sequential data. Can sequence-based RNN be an effective method of hyperspectral image classification? In this paper, we propose a novel RNN model that can effectively analyze hyperspectral pixels as sequential data and then determine information categories via network reasoning. As far as we know, this is the first time that an RNN framework has been proposed for hyperspectral image classification. Specifically, our RNN makes use of a newly proposed activation function, parametric rectified tanh (PRetanh), for hyperspectral sequential data analysis instead of the popular tanh or rectified linear unit. The proposed activation function makes it possible to use fairly high learning rates without the risk of divergence during the training procedure. Moreover, a modified gated recurrent unit, which uses PRetanh for hidden representation, is adopted to construct the recurrent layer in our network to efficiently process hyperspectral data and reduce the total number of parameters. Experimental results on three airborne hyperspectral images suggest competitive performance in the proposed mode. In addition, the proposed network architecture opens a new window for future research, showcasing the huge potential of deep recurrent networks for hyperspectral data analysis.
Autors: Lichao Mou;Pedram Ghamisi;Xiao Xiang Zhu;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jul 2017, volume: 55, issue:7, pages: 3639 - 3655
Publisher: IEEE
 

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