###### Accueil » Publications dans le domaines des technologies » 10-2017
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 Publications dans les journaux scientifiques dans le domaine de l'ingénierie : 10-2017 trié par par titre, page: 3
» Channel Equalization and Phase Noise Compensation Free DAPSK-OFDM Transmission for Coherent PON System
 Résumé:Channel equalization and phase noise compensation are required in coherent optical orthogonal frequency-division multiplexing (CO-OFDM) transmission systems for reliable performance. In general, redundant data such as training symbols and pilot tones are necessary for channel and phase noise estimation in quadrature amplitude modulation (QAM) based CO-OFDM systems, which reduces the spectral efficiency of the system. Especially, in the coherent passive optical network (PON), the redundancy increases as the number of subscribers increases. In this letter, we propose a differential amplitude shift keying (DAPSK)-based CO-OFDM transmission for PON system, which does not require channel equalization and phase noise compensation processes. The proposed DAPSK-based CO-OFDM transmission was experimentally demonstrated, and the performance according to receiver launched power and the number of subcarriers was compared with QAM-based CO-OFDM. Auteurs: Kyoung-Hak Mun;Sang-Min Jung;Soo-Min Kang;Sang-Kook Han; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 9 Editeur: IEEE Document complet vers site de l'éditeur
» Channel Estimation for Optical-OFDM-Based Multiuser MISO Visible Light Communication
 Résumé:A least squares-based channel estimation algorithm is proposed for optical orthogonal frequency division multiplexing-based multiuser multiple input single output visible light communications. The pilot sequence and pilot tones are optimized to derive the minimum-mean-square error of the channel estimation. Each user estimates the channel independently, and sends the estimates of the channels to the transmitter. Based on the estimated channels, zero-forcing precoding is applied at the transmitter to achieve the spatial multiplexing gain. The simulated performances of channel estimation and data detection are provided. Auteurs: Liang Wu;Julian Cheng;Zaichen Zhang;Jian Dang;Huaping Liu; Apparue dans: IEEE Photonics Technology Letters Date publication: 10.-2017, volume: 29, issue:20, pages: 1727 - 1730 Editeur: IEEE Document complet vers site de l'éditeur
» Channel Selection for Secondary Users in Decentralized Network of Unknown Size
 Résumé:In this letter, the challenge of optimal channel selection among the non-cooperative and unknown number of secondary (i.e., unlicensed) users (SUs) in the decentralized network is addressed. The proposed scheme consists of two phases: estimation and ranking (ER) phase and high throughput (HT) phase. In the ER phase, each SU chooses the channel randomly. Based on the sensing and collision outcomes, the proposed mathematical expression allows the SUs to independently estimate the channel ranking and the number of active SUs, $U$ . In the HT phase, the SUs follow collision-free hopping to exploit top $U$ channels. An upper bound on the time required for the SU orthogonalization in the HT phase, loss in throughput, and number of channel switchings are derived. Theoretical analysis and simulation results validate the superiority of the proposed scheme over existing state-of-the-art schemes. Auteurs: Rohit Kumar;Sumit J. Darak;Ankit Yadav;Ajay K. Sharma;Rajiv K. Tripathi; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2186 - 2189 Editeur: IEEE Document complet vers site de l'éditeur
» Characteristics of Doped n+ GaAs Thermopile-Based RF MEMS Power Sensors for MMIC Applications
 Résumé:This letter presents characteristics of thermopile-based radio frequency microelectromechanical system (RF MEMS) power sensors with different doped n+ GaAs concentrations, in order to improve sensitivity and signal-noise ratio (SNR). These sensors employ the conversion principle of RF power-heat-electricity, where two materials of AuGeNi/Au and n+ GaAs are designed to constitute two arms of the thermopile. The effects of four doping concentrations of n+ GaAs on the sensitivity and SNR of the power sensors are investigated. The RF MEMS power sensors are fabricated by a GaAs monolithic microwave integrated circuit (MMIC)-compatible process. Experiments show that these power sensors produce return losses of less than −28.3 dB up to 20 GHz. For the doped n+ GaAs concentrations of $2.4\times 10^{{18}}$ , $8.5\times 10^{{17}}$ , $3.2\times 10^{{17}}$ , and $1.9\times 10^{{17}}$ cm−3, measured sensitivities are about 84.10, 101.04, 209.82, and $395.52~\mu \text{V}$ /mW at 1 GHz and about 45.87, 54.11, 104.15, and $212.53~\mu \text{V}$ /mW at 20 GHz, respectively, while the resulting SNR are about $4.27\times 10^{{6}}$ , $3.08 \times 10^{{6}}$ , $3.91\times 10^{{6}}$ , and $5.70\times 10^{{6}}~\text{W}^{{-1}}$ at 1 GHz and about $2.33\times 10^{{6}}, 1.65\times 10^{{6}}$ , $1.94\times 10^{{6}}$ , and $3.06\times 10^{{6}}~\text{W}^{{-1}}$ at 20 GHz, respectively. With the decrease of doping concentration, the sensitivity increases but the SNR decreases first and then increases. Auteurs: Zhiqiang Zhang;Xiaoping Liao; Apparue dans: IEEE Electron Device Letters Date publication: 10.-2017, volume: 38, issue:10, pages: 1473 - 1476 Editeur: IEEE Document complet vers site de l'éditeur
» Characteristics of Electromagnetic Disturbance for Intelligent Component Due to Switching Operations via a 1100 kV AC GIS Test Circuit
 Résumé:Switching operation of the disconnector in gas-insulated switchgear (GIS) results in very fast transient overvoltage in GIS pipes. In a smart substation, this process induces disturbance voltage on the port of the intelligent component fixed on GIS pipes or placed in the local cabinet nearby, which then may lead to the failure of the equipment. The experimental results of the port disturbance voltage during the switching operation via a 1100 kV test circuit are first reported in this paper. The test arrangement, including both 70 opening operations and 70 closing operations, had been performed. The influences of different grounding schemes of cable shield on port disturbance had been investigated. Three different cases of the terminal load had also been considered: open circuit, short circuit, and 50 Ω. Over 100 000 micro-pulses had been extracted from the disturbance voltage waveforms. The waveform characteristics including peak voltage, rise-time, oscillation frequency, and decaying had been obtained by statistical analysis of these micro-pulses. Furthermore, the differences between measured waveforms and the IEC 61000-4-18 immunity test standard waveform had been discussed. Auteurs: Heng-Tian Wu;Xiang Cui;Xiao-Fan Liu;Chong-Qing Jiao;Rong Hu;Wei-Jiang Chen;Lei Wang; Apparue dans: IEEE Transactions on Power Delivery Date publication: 10.-2017, volume: 32, issue:5, pages: 2228 - 2237 Editeur: IEEE Document complet vers site de l'éditeur
» Characterization and Evaluation of the State-of-the-Art 3.3-kV 400-A SiC MOSFETs
 Résumé:Since their introduction, the SiC-based semiconductors have been of special interest to the field of power electronics, enabling increase in system efficiency, maximum operating temperature, and power density. In higher voltage range, these semiconductors are at early stage of development and yet are not commercialized. This paper investigates state-of-the-art noncommercialized 3.3-kV 400-A full-SiC MOSFETs where for the first time such MOSFETs are thoroughly characterized and their performance is evaluated and compared against similar rating Si counterparts. Extensive static and dynamic characterizations are done with emphasize on enabling conduction and switching loss calculation in any target application. I-V curves for MOSFET and Shottky-barrier diode (SBD), RDSon, C-V curves and threshold voltages are addressed by measurement at different temperatures. Moreover, the SiC MOSFETs are tested in chopper circuit with an inductive load for measurement of switching losses. This is done at 2-kV bus voltage from 50 up to 400 A load current. Finally, simulations are done in MATLAB/Simulink to evaluate the performance of 3.3-kV 400-A modules in medium-voltage high-power industrial drive application. The case study shows advantages of the 3.3-kV SiC MOSFET technology over 3.3-kV Si IGBTs and 1.7-kV SiC MOSFETs from efficiency, installed die area and power density points of view. Auteurs: Alinaghi Marzoughi;Jun Wang;Rolando Burgos;Dushan Boroyevich; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 8247 - 8257 Editeur: IEEE Document complet vers site de l'éditeur
» Characterization of $\gamma$ -Ray Cross Talk in Cherenkov-Based Detectors for Active Interrogation Imaging Applications
 Résumé:In imaging arrays, the sensors are typically packed as tightly as possible to maximize spatial resolution, which leads to detector-to-detector scatter, or cross talk, adding to image noise and hindering contrast. In this paper, we compare custom-made quartz-based Cherenkov detectors with an inherent energy threshold to low-energy photons to standard sodium iodide detectors, which are typically used for x-ray detection due to their efficiency and spectroscopic capabilities. In particular, we evaluate pulse pileup and cross talk effects in high-flux applications. The quartz detectors, while having reduced intrinsic efficiency, outperform the sodium iodide with regards to pileup and cross talk. Simulation further shows that even at a 4 mm edge-to-edge separation, cross talk contributes less than 2% of the total signal in Cherenkov detectors. Auteurs: Joseph Harms;Paul B. Rose;Anna Erickson; Apparue dans: IEEE Sensors Journal Date publication: 10.-2017, volume: 17, issue:20, pages: 6707 - 6715 Editeur: IEEE Document complet vers site de l'éditeur
» Characterization of $\gamma$ -Ray Cross Talk in Cherenkov-Based Detectors for Active Interrogation Imaging Applications
 Résumé:In imaging arrays, the sensors are typically packed as tightly as possible to maximize spatial resolution, which leads to detector-to-detector scatter, or cross talk, adding to image noise and hindering contrast. In this paper, we compare custom-made quartz-based Cherenkov detectors with an inherent energy threshold to low-energy photons to standard sodium iodide detectors, which are typically used for x-ray detection due to their efficiency and spectroscopic capabilities. In particular, we evaluate pulse pileup and cross talk effects in high-flux applications. The quartz detectors, while having reduced intrinsic efficiency, outperform the sodium iodide with regards to pileup and cross talk. Simulation further shows that even at a 4 mm edge-to-edge separation, cross talk contributes less than 2% of the total signal in Cherenkov detectors. Auteurs: Joseph Harms;Paul B. Rose;Anna Erickson; Apparue dans: IEEE Sensors Journal Date publication: 10.-2017, volume: 17, issue:20, pages: 6707 - 6715 Editeur: IEEE Document complet vers site de l'éditeur
» Characterization of $\gamma$ -Ray Cross Talk in Cherenkov-Based Detectors for Active Interrogation Imaging Applications
 Résumé:In imaging arrays, the sensors are typically packed as tightly as possible to maximize spatial resolution, which leads to detector-to-detector scatter, or cross talk, adding to image noise and hindering contrast. In this paper, we compare custom-made quartz-based Cherenkov detectors with an inherent energy threshold to low-energy photons to standard sodium iodide detectors, which are typically used for x-ray detection due to their efficiency and spectroscopic capabilities. In particular, we evaluate pulse pileup and cross talk effects in high-flux applications. The quartz detectors, while having reduced intrinsic efficiency, outperform the sodium iodide with regards to pileup and cross talk. Simulation further shows that even at a 4 mm edge-to-edge separation, cross talk contributes less than 2% of the total signal in Cherenkov detectors. Auteurs: Joseph Harms;Paul B. Rose;Anna Erickson; Apparue dans: IEEE Sensors Journal Date publication: 10.-2017, volume: 17, issue:20, pages: 6707 - 6715 Editeur: IEEE Document complet vers site de l'éditeur
» Characterization of CMOS-MEMS Resonant Pressure Sensors
 Résumé:Comprehensive characterization results of CMOS-microelectromechanical systems resonant pressure sensor are presented. We have extensively evaluated the key performance parameters of our device in terms of quality factor ( $Q$ ) variations under variable conditions of temperature and pressure, characterized by Knudsen number ( $K_{n}$ ). The fundamental frequency of the reported device is 104.3 kHz. Over the full-scale pressure range of 0.1 to 100 kPa and a temperature range of −10 °C to 85 °C, $Q$ from 450 to 62.6 have been obtained. Besides, static variations of the device capacitance have been measured and analyzed with temperature to evaluate the spring softening and the pull-in effects. A nonlinearity analysis has been performed to assess the device stability. Furthermore, a statistical mismatch analysis has been carried out to determine the deviation of resonance with etching time and ascertain maximum device yield. With our in-house back-end of line metal-layer release, this sensor can be monolithically embedded in the same substrate as standard CMOS integrated circuits, resulting in a significant cost and area reduction. Auteurs: Saoni Banerji;Daniel Fernández;Jordi Madrenas; Apparue dans: IEEE Sensors Journal Date publication: 10.-2017, volume: 17, issue:20, pages: 6653 - 6661 Editeur: IEEE Document complet vers site de l'éditeur
» Characterization of Seafloor Roughness to Support Modeling of Midfrequency Reverberation
 Résumé:A seafloor laser scanner was deployed in the Gulf of Mexico during the 2013 Target and Reverberation Experiment (TREX13). This system collected digital elevation maps at 14 locations along the main reverberation track, and these measurements provide roughness power spectra for modeling seafloor acoustic scattering. The spectra were divided into two regimes according to the mid and high-frequency acoustic measurements made during the experiment. For the wave numbers corresponding to the midfrequency regime (2–4 kHz), the spectra could be approximated using the mean spectral exponent derived from the all of the spectra. With this spectral exponent, the best fit spectral strengths were found to be negatively correlated to the backscatter levels measured at 400 kHz using a multibeam echosounder (MBES). While the scattering mechanisms at 400 kHz are not influenced by the roughness at these low wave numbers, this correlation may be indirectly related to the bioturbation and the spatial variation of the shell content. A more pronounced correlation was found for the high wave numbers, where again a single spectral exponent could be used to a good approximation. In this case, the spectral strengths were also linearly related to the MBES backscattering level but with a positive correlation. For these wave numbers, the roughness is largely influenced by the shell content, which is also the dominant scattering mechanism at 400 kHz. The correlations between the roughness and the MBES measurements provide a means to approximate the seafloor roughness parameters in both wave number regimes throughout the experiment site. For the low wave number spectrum, an alternative approach is also proposed, which uses the spectral parameters for the mean spectrum to approximate the roughness throughout the TREX13 site. Auteurs: Brian T. Hefner; Apparue dans: IEEE Journal of Oceanic Engineering Date publication: 10.-2017, volume: 42, issue:4, pages: 1110 - 1124 Editeur: IEEE Document complet vers site de l'éditeur
» Characterization of the CVD Graphene Monolayer as an Active Element of a One-Port Microwave Device
 Résumé:The one-port configuration of a microwave device is the simplest architecture for graphene ultrafast (photo-)resistors, (photo-)diodes, sensors, and photodetectors. Here, this configuration is realized by a segment of coplanar waveguide (CPW) loaded with a CVD graphene monolayer shorted to the ground. The magnitude and phase of the reflection coefficient ( ${S}_{11}$ parameter) measured in the $0.1~\div ~26$ GHz frequency range are presented for undisturbed structures as well as for structures illuminated by white light and electrostatically polarized with the backgate. A simple and robust de-embedding procedure based on the signal flow graph and allowing for a simultaneous extraction of the parameters characterizing the CPW segment and the graphene monolayer is proposed. The graphene impedance at microwave frequencies is in good agreement with the value of dc sheet resistance obtained from van der Pauw measurements. The back-gate voltage modulation is an efficient way to modulate both the dc sheet resistance and the impedance. In particular, the Dirac point can be achieved both at microwave frequencies and at dc. An equivalent circuit model consists of only the resistance and capacitance connected in parallel, because of good quality ohmic contacts and a negligible inductance as a result of low-current flow in high-resistance graphene samples. Auteurs: Jarosław Judek;Mariusz Zdrojek;Jan Sobieski;Aleksandra Przewłoka;Jerzy K. Piotrowski; Apparue dans: IEEE Transactions on Electron Devices Date publication: 10.-2017, volume: 64, issue:10, pages: 4340 - 4345 Editeur: IEEE Document complet vers site de l'éditeur
» Characterization of Y-Bias Ferrite Materials for Tunable Antenna Applications Using a Partially Filled Rectangular Waveguide
 Résumé:A methodology for measuring the constitutive parameters of a ferrite material is presented. This method can be used to assist the prediction of the properties of tunable antennas that use ferrite material as a substrate or tuning component. A nontraditional characterization method is required due to the general unavailability of samples of a sufficient size to fill the entire cross sections of waveguides appropriate for lower frequencies where gyromagnetic properties are most pronounced, and the difficulty of predicting or approximating the applied bias magnetic field. The proposed method overcomes the limitation of sample size by requiring only partial filling of a rectangular waveguide. It overcomes a lack of knowledge of the bias field by including the field as an unknown to be determined by the extraction process. The required theoretical reflection and transmission coefficients of the partially filled waveguide are determined using a mode-matching technique. A nonlinear least squares method is employed to extract the gyromagnetic material parameters and the bias field using optimization algorithms in MATLAB. The extracted parameters of a representative commercial ferrite obtained from multiple experimental configurations are compared with the values provided by the sample manufacturer to demonstrate the feasibility of this technique. Auteurs: Junyan Tang;Amin Tayebi;Benjamin Crowgey;Edward J. Rothwell;Balasubramaniam Shanker;Leo C. Kempel;Michael J. Havrilla; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5279 - 5288 Editeur: IEEE Document complet vers site de l'éditeur
» Characterizing Transmission Loss Variability During the Target and Reverberation Experiment 2013
 Résumé:A significant driver of uncertainty in sonar performance is the variability in underwater acoustical propagation caused by environmental fluctuations and uncertainty in the position of sources, targets, and receivers. A set of echo-repeat experiments was conducted during the Target and Reverberation Experiment 2013 (TREX13), a sea trial that took place in April to May 2013 in the Gulf of Mexico near Panama City, FL, USA. The variability in measured transmission loss (TL) was characterized using two different methods: Variability with respect to a mean observed TL, and variability with respect to modeled TL. Both one-way and quasi-reciprocal two-way TL measurements at 2250 and 7500 Hz were analyzed to characterize the variability at timescales ranging from less than one second to several days, with the results indicating that the acoustic propagation fluctuates stochastically on all these time scales. The results of statistical tests suggest that the TL variability can be treated as Gaussian fluctuations about a central TL obtained from an acoustic propagation model, with standard deviations of 5 dB over timescales up to one day, or 10 dB over timescales from one to six days. Auteurs: Cristina D. S. Tollefsen;Sean P. Pecknold; Apparue dans: IEEE Journal of Oceanic Engineering Date publication: 10.-2017, volume: 42, issue:4, pages: 1135 - 1145 Editeur: IEEE Document complet vers site de l'éditeur
» Charge-Controlled Oscillators and Their Application in Frequency Synthesis
 Résumé:A tunable oscillator, whose frequency is a function of the total charge in the oscillating nodes, is introduced in this brief. Three variants of charge-controlled oscillators (QCOs) that oscillate around 3.6 GHz are presented. The figure-of-merits (FoMs) of these oscillators, obtained from simulation, are 169, 172, and 178 dB, respectively. The measured FoM of the third QCO is 179 dB. We also show that the use of a QCO in a frequency synthesizer eliminates the requirement of an explicit loop filter. Furthermore, an example of an all-digital phase-locked loop based on a QCO is shown. Auteurs: Roohie Kaushik;Shouri Chatterjee;G. S. Visweswaran; Apparue dans: IEEE Transactions on Circuits and Systems II: Express Briefs Date publication: 10.-2017, volume: 64, issue:10, pages: 1127 - 1131 Editeur: IEEE Document complet vers site de l'éditeur
» Chip Averaging Chaotic ON–OFF Keying: A New Non-Coherent Modulation for Ultra Wide Band Direct Chaotic Communication
 Résumé:This letter proposes a new adaptive threshold modulation scheme, called chip averaging chaotic ON–OFF keying (CA-COOK). This new scheme is applied to non-coherent modulations in ultra-wideband direct chaotic communication. Mainly, the proposed method deals with the “estimation problem” caused by the bit energy variation of the chaotic carrier signal. This is completed by adopting the Cell Averaging Constant False Alarm Rate paradigm used in radar, and each bit period is divided into several chips, where one of those chips is bearing the information. Bit-error-rate performance in additive-white-Gaussian-noise, two-path Rayleigh, and IEEE802.15.4a office NLOS channel models, is analyzed and compared with well-known and challenging chaos-based communication systems. Simulation results show the effectiveness of the proposed CA-COOK. Auteurs: Ammar Mesloub;Arezki Boukhelifa;Omar Merad;Said Saddoudi;Arezki Younsi;Mustapha Djeddou; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2166 - 2169 Editeur: IEEE Document complet vers site de l'éditeur
» Chip-Scale Near-Field Resonant Power Transfer via Elastic Waves
 Résumé:This paper reports on the proof-of-concept demonstration of an approach for the synthesis of a through package charging and authenticating communication link enabled by GHz-range aluminum nitride (AlN) piezoelectric transducers. The acoustic link is formed by two thickness-mode acoustic transducers placed on the two sides of a packaging substrate. The link leverages the enhancement of energy transfer that occurs at resonance; 1- $\mu \text{m}$ -thick (2.7 GHz) and 6- $\mu \text{m}$ -thick (500 MHz) AlN acoustic links are demonstrated showing substantial enhancement of power transfer efficiencies (PTE) when using thicker AlN substrates. PTEs of −8 dB at 2.7 GHz and −2 dB at 500 MHz are measured for transducers’ size of $1\times 100\times 100~\mu \text{m}^{3}$ and $6\times 100\times 100~\mu \text{m}^{3}$ through 700- and 500- $\mu \text{m}$ -thick silicon substrates, respectively. The experimental values are in very close agreement with the analytical model of the acoustic link. The potential misalignment between the two transducers is the main limitation of this approach. To overcome this challenge, acoustic phased arrays are devised to enable steering of the transmitted beam. Preliminary results on the steering capability demonstrate about 8 dB of improvement in PTE via a two-element array when dealing with a 100- $\mu \text{m}$ misalignment. This paper is the first step toward the development of next-generation high-efficiency and micro-scale power transfer - nits that could energize chips through packages. [2017-0010] Auteurs: Emad Mehdizadeh;Gianluca Piazza; Apparue dans: Journal of Microelectromechanical Systems Date publication: 10.-2017, volume: 26, issue:5, pages: 1155 - 1164 Editeur: IEEE Document complet vers site de l'éditeur
» Ciphertext-Only Attack on Phase-Shifting Interferometery-Based Encryption
 Résumé:The phase-shifting interferometry-based (PSI-based) encryption is one of most typical optical encryption systems. In this paper, we demonstrate a new approach to ciphertext-only attack (COA) on PSI-based encryption, revealing that there is serious security risk in PSI-based encryption. With the proposed COA approach, an opponent can crack the ciphertexts directly without use of the keys of the system. This demonstration, as far as our best knowledge, shows the PSI technique is vulnerable to COA for the first time. A series of attack results are shown to demonstrate the feasibility and robustness of the attack method. Our study reveals a critical security issue that should be taken in to account when designing an optical information security system. Auteurs: Tuo Li;Zongcheng Miao;Yishi Shi; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» Classification of Protein Structure Classes on Flexible Neutral Tree
 Résumé:Accurate classification on protein structural is playing an important role in Bioinformatics. An increase in evidence demonstrates that a variety of classification methods have been employed in such a field. In this research, the features of amino acids composition, secondary structure's feature, and correlation coefficient of amino acid dimers and amino acid triplets have been used. Flexible neutral tree (FNT), a particular tree structure neutral network, has been employed as the classification model in the protein structures’ classification framework. Considering different feature groups owing diverse roles in the model, impact factors of different groups have been put forward in this research. In order to evaluate different impact factors, Impact Factors Scaling (IFS) algorithm, which aim at reducing redundant information of the selected features in some degree, have been put forward. To examine the performance of such framework, the 640, 1189, and ASTRAL datasets are employed as the low-homology protein structure benchmark datasets. Experimental results demonstrate that the performance of the proposed method is better than the other methods in the low-homology protein tertiary structures. Auteurs: Wenzheng Bao;Dong Wang;Yuehui Chen; Apparue dans: IEEE/ACM Transactions on Computational Biology and Bioinformatics Date publication: 10.-2017, volume: 14, issue:5, pages: 1122 - 1133 Editeur: IEEE Document complet vers site de l'éditeur
» Classification of Schizophrenia Based on Individual Hierarchical Brain Networks Constructed From Structural MRI Images
 Résumé:With structural magnetic resonance imaging (MRI) images, conventional methods for the classification of schizophrenia (SCZ) and healthy control (HC) extract cortical thickness independently at different regions of interest (ROIs) without considering the correlation between these regions. In this paper, we proposed an improved method for the classification of SCZ and HC based on individual hierarchical brain networks constructed from structural MRI images. Our method involves constructing individual hierarchical networks where each node and each edge in these networks represents a ROI and the correlation between a pair of ROIs, respectively. We demonstrate that edge features make significant improvement in performance of SCZ/HC classification, when compared with only node features. Classification performance is further investigated by combining edge features with node features via a multiple kernel learning framework. The experimental results show that our proposed method achieves an accuracy of 88.72% and an area under the receiver operating characteristic (ROC) curve (AUC) of 0.9521 for SCZ/HC classification, which demonstrate that our proposed method is efficient and promising for clinical applications for the diagnosis of SCZ via structural MRI images. Therefore, this paper provides an alternative method for extracting high-order cortical thickness features from structural MRI images for classification of neurodegenerative diseases such as SCZ. Auteurs: Jin Liu;Min Li;Yi Pan;Fang-Xiang Wu;Xiaogang Chen;Jianxin Wang; Apparue dans: IEEE Transactions on NanoBioscience Date publication: 10.-2017, volume: 16, issue:7, pages: 600 - 608 Editeur: IEEE Document complet vers site de l'éditeur
» Closed-Form BER Expressions of QPSK Constellation for Uplink Non-Orthogonal Multiple Access
 Résumé:Non-orthogonal multiple access (NOMA) is an attractive multiple access technique to achieve the optimal system capacity region. A great deal of recent attention has been devoted to the study of the NOMA system capacity performance. However, the exact bit error rate (BER) expressions of NOMA systems have not been derived yet. We provide the exact closed-form BER expressions of the QPSK constellation for an uplink NOMA system over an additive white Gaussian noise channel. Finally, the validity of our derived BER expressions is verified through simulations. Auteurs: Xiaolu Wang;Fabrice Labeau;Lin Mei; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2242 - 2245 Editeur: IEEE Document complet vers site de l'éditeur
» Closed-Form SER Expression for APSK Based on the Kite Structure
 Résumé:In communication systems, amplitude phase shift keying (APSK) arises as a potential solution to mitigate performance degradations due to channel non-linearities. Since it combines the characteristics of PSK and those of amplitude shift keying (ASK), APSK is also likely to be robust in systems influenced by phase noise. It is, therefore, solicited in cascaded systems involving visible light communications (VLC) as the second communication technology. This letter proposes the design of an APSK constellation, based on the kite structure, suitable for such cascaded systems. The constellation design is detailed and the symbol error probability is derived in closed-form. The bit error rate performance is compared with those of quadrature amplitude modulation (QAM) and PSK. Findings reveal that for $2\eta = 4$ ( $\eta$ being the common number of symbols per ring), the proposed APSK scheme has similar performance with ${Q}$ PSK and 4QAM, and, for $2\eta > 8$ , the APSK scheme outperforms the corresponding PSK, making it a good candidate for cascaded VLC systems. Even though the proposed scheme is outperformed by QAM, it gains up to about 5 dB over the PSK for an error rate of $10^{-8}$ . Auteurs: Alain Richard Ndjiongue;Hendrik C. Ferreira;Telex M. N. Ngatched; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2182 - 2185 Editeur: IEEE Document complet vers site de l'éditeur
» Closed-Loop Neurostimulators: A Survey and A Seizure-Predicting Design Example for Intractable Epilepsy Treatment
 Résumé:First, existing commercially available open-loop and closed-loop implantable neurostimulators are reviewed and compared in terms of their targeted application, physical size, system-level features, and performance as a medical device. Next, signal processing algorithms as the primary strength point of the closed-loop neurostimulators are reviewed, and various design and implementation requirements and trade-offs are discussed in details along with quantitative examples. The review results in a set of guidelines for algorithm selection and evaluation. Second, the implementation of an inductively-powered seizure-predicting microsystem for monitoring and treatment of intractable epilepsy is presented. The miniaturized system is comprised of two miniboards and a power receiver coil. The first board hosts a 24-channel neurostimulator system on chip [15] fabricated in a $0.13\;\mu \text{m}$ CMOS technology and performs neural recording, on-chip digital signal processing, and electrical stimulation. The second board communicates recorded brain signals as well as signal processing results wirelessly. The multilayer flexible coil receives inductively-transmitted power. The system is sized at 2 $\times$ 2 $\times$ 0.7 $\text{cm}^3$ and weighs 6 g. The approach is validated in the control of chronic seizures in vivo in freely moving rats. Auteurs: Hossein Kassiri;Sana Tonekaboni;M. Tariqus Salam;Nima Soltani;Karim Abdelhalim;Jose Luis Perez Velazquez;Roman Genov; Apparue dans: IEEE Transactions on Biomedical Circuits and Systems Date publication: 10.-2017, volume: 11, issue:5, pages: 1026 - 1040 Editeur: IEEE Document complet vers site de l'éditeur
 Résumé:As accurate malware detection on mobile devices requires fast process of a large number of application traces, cloud-based malware detection can utilize the data sharing and powerful computational resources of security servers to improve the detection performance. In this paper, we investigate the cloud-based malware detection game, in which mobile devices offload their application traces to security servers via base stations or access points in dynamic networks. We derive the Nash equilibrium (NE) of the static malware detection game and present the existence condition of the NE, showing how mobile devices share their application traces at the security server to improve the detection accuracy, and compete for the limited radio bandwidth, the computational and communication resources of the server. We design a malware detection scheme with Q-learning for a mobile device to derive the optimal offloading rate without knowing the trace generation and the radio bandwidth model of other mobile devices. The detection performance is further improved with the Dyna architecture, in which a mobile device learns from the hypothetical experience to increase its convergence rate. We also design a post-decision state learning-based scheme that utilizes the known radio channel model to accelerate the reinforcement learning process in the malware detection. Simulation results show that the proposed schemes improve the detection accuracy, reduce the detection delay, and increase the utility of a mobile device in the dynamic malware detection game, compared with the benchmark strategy. Auteurs: Liang Xiao;Yanda Li;Xueli Huang;XiaoJiang Du; Apparue dans: IEEE Transactions on Mobile Computing Date publication: 10.-2017, volume: 16, issue:10, pages: 2742 - 2750 Editeur: IEEE Document complet vers site de l'éditeur
» Cluster Synchronization of Coupled Genetic Regulatory Networks With Delays via Aperiodically Adaptive Intermittent Control
 Résumé:In this paper, we study the cluster synchronization of coupled genetic regulatory networks with time-varying delays via aperiodically adaptive intermittent control on some nodes. The network is intermittently coupled and the intra-cluster coupling strength is adaptively adjusted. The graph of the coupling topology of each cluster is only required to have a directed spanning tree. Two cases of delays are considered. In the first case, by using the switching Lyapunov-based function and Razumikhin-type technique, the cluster synchronization criterion is presented which indicates that the cluster synchronization is realized via the aperiodically adaptive intermittent control. The second case is investigated by using the switching Lyapunov functional. Both the cluster synchronization criteria are established by the Linear Matrix Inequalities (LMIs), the lower bound of the aperiodical time span, and the maximum uncontrolled ratio. It is shown that the results are applicable to both the situations that the upper bound of the delay is larger and smaller than the lower bound of the aperiodical coupling and control width. Numerical simulations are carried out to illustrate the theoretical results. Auteurs: Zhi-Hong Guan;Dandan Yue;Bin Hu;Tao Li;Feng Liu; Apparue dans: IEEE Transactions on NanoBioscience Date publication: 10.-2017, volume: 16, issue:7, pages: 585 - 599 Editeur: IEEE Document complet vers site de l'éditeur
» Cluster-Aware Virtual Machine Collaborative Migration in Media Cloud
 Résumé:Media cloud has become a promising paradigm for deploying large-scale streaming media applications at a reduced cost. Due to dynamic and diverse demands of users, media cloud presents two crucial characteristics: high resource consumption and dynamic traffic among media servers. Consequently, Virtual Machine (VM) migration in media cloud is highly required to suit varying resource requirements and the dynamic traffic patterns. Moreover, migration of such bandwidth-intensive media applications in media cloud needs cautious handling, especially for the internal traffic of Data Center Networks (DCN). However, existing media cloud resource management schemes or traffic-aware VM deployment approaches are insufficient for media cloud, ignoring the characteristics of either cloud infrastructure or media streaming requirements. In this paper, we propose a cluster-aware VM collaborative migration scheme for media cloud, tightly integrating clustering, placement, and dynamic migration process. The scheme employs a clustering algorithm and a placement algorithm to obtain ideal migration strategies for newly perceived media server clusters, and a migration algorithm to effectively accomplish the migration process of media servers. Evaluation results demonstrate that our scheme can effectively migrate virtual media servers in media cloud, while reducing the total internal traffic in DCN under the resource consumption constraints of media streaming applications. Auteurs: Weizhan Zhang;Yuxuan Chen;Xiang Gao;Zhichao Mo;Qinghua Zheng;Zongqing Lu; Apparue dans: IEEE Transactions on Parallel and Distributed Systems Date publication: 10.-2017, volume: 28, issue:10, pages: 2808 - 2822 Editeur: IEEE Document complet vers site de l'éditeur
» Clustered Voltage Balancing Mechanism and Its Control Strategy for Star-Connected Cascaded H-Bridge STATCOM
 Résumé:To explore the clustered voltage balancing mechanism of the star-connected cascaded H-Bridge (SCHB) STATCOM, this paper analyzes the relationship between the active power and the control variables-modulation reference voltages in a dq frame through positive and negative sequence component decomposition. The derived relationship in the dq frame reveals that the negative sequence modulation reference voltage is capable of redistributing the active power among three phases and also the SCHB STATCOM features the clustered voltage self-stabilizing without any additional clustered voltage balancing control. To eliminate the differences of three clustered voltages, a new clustered voltage balancing control is proposed by regulating negative sequence modulation reference voltage in the dq frame. Its balancing mechanism is analyzed in detail and a simple implementation is presented as well. The effectiveness of the proposed control is verified by experimental results on a 400 V/15 kvar SCHB STATCOM. Auteurs: Daorong Lu;Jiangfeng Wang;Jianhui Yao;Sen Wang;Jianxin Zhu;Haibing Hu;Li Zhang; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7623 - 7633 Editeur: IEEE Document complet vers site de l'éditeur
» CMOS Ultralow Power Brain Signal Acquisition Front-Ends: Design and Human Testing
 Résumé:Two brain signal acquisition (BSA) front-ends incorporating two CMOS ultralow power, low-noise amplifier arrays and serializers operating in mosfet weak inversion region are presented. To boost the amplifier's gain for a given current budget, cross-coupled-pair active load topology is used in the first stages of these two amplifiers. These two BSA front-ends are fabricated in 130 and 180 nm CMOS processes, occupying 5.45 mm $^{2}$ and 0.352 mm $^{2}$ of die areas, respectively (excluding pad rings). The CMOS 130-nm amplifier array is comprised of 64 elements, where each amplifier element consumes 0.216 $\mu$ W from 0.4 V supply, has input-referred noise voltage (IRNoise) of 2.19 $\mu$V$_{\text{RMS}}$ corresponding to a power efficiency factor (PEF) of 11.7, and occupies 0.044 mm $^{2}$ of die area. The CMOS 180 nm amplifier array employs 4 elements, where each element consumes 0.69 $\mu$ W from 0.6 V supply with IRNoise of 2.3 $\mu$ V$_{\text{RMS}}$ (corresponding to a PEF of 31.3) and 0.051 mm$^{2}$ of die area. Noninvasive electroencephalographic and invasive electrocorticographic signals were recorded real time directly on able-bodied human subjects, showing feasibility of using these analog front-ends for futur- fully implantable BSA and brain– computer interface systems. Auteurs: Alireza Karimi-Bidhendi;Omid Malekzadeh-Arasteh;Mao-Cheng Lee;Colin M. McCrimmon;Po T. Wang;Akshay Mahajan;Charles Yu Liu;Zoran Nenadic;An H. Do;Payam Heydari; Apparue dans: IEEE Transactions on Biomedical Circuits and Systems Date publication: 10.-2017, volume: 11, issue:5, pages: 1111 - 1122 Editeur: IEEE Document complet vers site de l'éditeur
» Co-Design of Controller and Communication Topology for Vehicular Platooning
 Résumé:Small inter-vehicle distances can increase traffic throughput on highways. Human drivers are not able to drive safely under such conditions. To this aim, cooperative adaptive cruise control (CACC) systems have been developed, which require vehicles to communicate with each other through a wireless communication network. By communicating control-relevant information, the vehicles equipped with the CACC system are able to react more quickly to disturbances caused by preceding vehicles and, therefore, are able to maintain the desired (small) inter-vehicle distance while avoiding string instability. String stability relates to the propagation of the effect of disturbance on system states over the vehicle string. Commonly used approaches to design controllers yielding string stability, involve an iterative process requiring an a priori designed controller with a priori defined communication topology. The main contribution of this paper is to propose a synthesis strategy for both local controllers and the communication structure, while guaranteeing string stability for infinite-length vehicular strings. The obtained results are illustrated by model-based case studies. Auteurs: Amir Firooznia;Jeroen Ploeg;Nathan van de Wouw;Hans Zwart; Apparue dans: IEEE Transactions on Intelligent Transportation Systems Date publication: 10.-2017, volume: 18, issue:10, pages: 2728 - 2739 Editeur: IEEE Document complet vers site de l'éditeur
» Coastal Sea-Level Measurements Based on GNSS-R Phase Altimetry: A Case Study at the Onsala Space Observatory, Sweden
 Résumé:The characterization of global mean sea level is important to predict floods and to quantify water resources for human use and irrigation, especially in coastal regions. Recently, the application of global navigation satellite system reflectometry (GNSS-R) for water level monitoring has been successfully demonstrated. This paper focuses on the retrieval of sea surface height within a field experiment that was conducted at the Onsala Space Observatory (OSO) using the phase-based altimetry method. A continuous phase tracking algorithm, which relies on the GNSS amplitude and phase observations is proposed and works even under rough sea conditions at OSO’s coast. Factors impacting the phase-based altimetry model, i.e., atmospheric propagation effects of the GNSS signals and influence of the GNSS-R observation instrument, are discussed. The relationship between the yield of coherent GNSS-R compared to the overall recorded events and the wind speed is investigated in detail. Ground-based sea-level measurements from June 10 to July 3, 2015 demonstrate that altimetric information about the reflecting water surface can be obtained with a root mean square error of 4.37 cm with respect to a reference tide gauge (TG) data set. The sea surface changes, derived from our field experiment and the reference TG, are highly correlated with a correlation coefficient of 0.93. The altimetric information can be retrieved even when the sea surface is very rough, corresponding to wind speeds up to 13 m/s. Moreover, the use of inexpensive conventional GNSS antennas shows that the system is useful for future large-scale sea level monitoring applications including numerous low-cost coastal ground stations. Auteurs: Wei Liu;Jamila Beckheinrich;Maximilian Semmling;Markus Ramatschi;Sibylle Vey;Jens Wickert;Thomas Hobiger;Rüdiger Haas; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5625 - 5636 Editeur: IEEE Document complet vers site de l'éditeur
» Coding for Interactive Communication Correcting Insertions and Deletions
 Résumé:We consider the question of interactive communication, in which two remote parties perform a computation, while their communication channel is (adversarially) noisy. We extend here the discussion into a more general and stronger class of noise, namely, we allow the channel to perform insertions and deletions of symbols. These types of errors may bring the parties “out of sync,” so that there is no consensus regarding the current round of the protocol. In this more general noise model, we obtain the first interactive coding scheme that has a constant rate and tolerates noise rates of up to $1/18- \varepsilon$ . To this end, we develop a novel primitive we name edit-distance tree code. The edit-distance tree code is carefully designed to replace the Hamming distance constraints in Schulman’s tree codes (IEEE Trans. Inf. Theory, 1996), with a stronger edit-distance requirement. Auteurs: Mark Braverman;Ran Gelles;Jieming Mao;Rafail Ostrovsky; Apparue dans: IEEE Transactions on Information Theory Date publication: 10.-2017, volume: 63, issue:10, pages: 6256 - 6270 Editeur: IEEE Document complet vers site de l'éditeur
» Coding for the Large-Alphabet Adversarial Channel
 Résumé:We consider the problem of encoding an i.i.d. source into a set of symbols or messages that may be altered by an adversary while en route to the decoder. We focus in particular on the regime in which the number of messages is fixed while the blocklength of the source and the size of each message tend to infinity. For this fixed-blocklength, “large alphabet” channel, we show that combining an optimal rate-distortion code with an optimal error-correction code yields an optimal overall code for Gaussian sources with quadratic distortion and binary uniform sources with Hamming distortion but that it can be suboptimal by an arbitrarily large factor in general. We also consider the scenario in which the distortion constraint that the decoder must satisfy depends on the number of errors that occur. We show that the problem can be reduced operationally to one with erasures instead of errors in two special cases: one involving lossless reproduction of functions of the source and one in which the encoder and decoder share common randomness. Auteurs: Ebad Ahmed;Aaron B. Wagner; Apparue dans: IEEE Transactions on Information Theory Date publication: 10.-2017, volume: 63, issue:10, pages: 6347 - 6363 Editeur: IEEE Document complet vers site de l'éditeur
» Coding, Multicast, and Cooperation for Cache- Enabled Heterogeneous Small Cell Networks
 Résumé:Caching at the wireless edge is a promising approach to dealing with massive content delivery in heterogeneous wireless networks, which have high demands on backhaul. In this paper, a typical cache-enabled small cell network under heterogeneous file and network settings is considered using maximum distance separable (MDS) codes for content restructuring. Unlike those in the literature considering online settings with the assumption of perfect user request information, we estimate the joint user requests using the file popularity information and aim to minimize the long-term average backhaul load for fetching content from external storage subject to the overall cache capacity constraint by optimizing the content placement in all the cells jointly. Both multicast-aware caching and cooperative caching schemes with optimal content placement are proposed. In order to combine the advantages of multicast content delivery and cooperative content sharing, a compound caching technique, which is referred to as multicast-aware cooperative caching, is then developed. For this technique, a greedy approach and a multicast-aware in-cluster cooperative approach are proposed for the small-scale networks and large-scale networks, respectively. Mathematical analysis and simulation results are presented to illustrate the advantages of MDS codes, multicast, and cooperation in terms of reducing the backhaul requirements for cache-enabled small cell networks. Auteurs: Jialing Liao;Kai-Kit Wong;Yangyang Zhang;Zhongbin Zheng;Kun Yang; Apparue dans: IEEE Transactions on Wireless Communications Date publication: 10.-2017, volume: 16, issue:10, pages: 6838 - 6853 Editeur: IEEE Document complet vers site de l'éditeur
» Coherence in Multielement-Phased Vertical-Cavity Surface-Emitting Laser Arrays Using Resonance Tuning
 Résumé:We show that optical coupling can be achieved reproducibly and with high yield by resonance tuning the elements of substrate-emitting and top-emitting vertical-cavity surface-emitting laser arrays. The resonance tuning is enabled by electrical isolation of the lasing elements in the array, which in this paper is done by post fabrication processing. Prior to electrical isolation, the laser arrays exhibit incoherent optical properties. Using resonance tuning, both in-phase and out-of-phase coherent modes are observed. Auteurs: Bradley J. Thompson;Zihe Gao;Stewart T. M. Fryslie;Matthew T. Johnson;Dominic F. Siriani;Kent D. Choquette; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» Coherent Summation of Radiation From Four-Channel Shock-Excited RF Source Operating at 4 GHz and a Repetition Rate of 1000 Hz
 Résumé:Testing results of a generator based on the parallel gyromagnetic nonlinear transmission lines with saturated ferrite are presented. Practically identical and stable RF-modulated high-voltage nanosecond pulses were shaped in each of the four channels. The pulse amplitude reaches −175 kV at a modulation depth of RF oscillations to 50% and an effective frequency ~4 GHz. Power in the packet operation mode with a 1-s packet duration at pulse repetition frequencies up to 1000 Hz (in packet) was supplied by a solid-state driver. The electric field strength achieved 250 kV/m at a distance of 3 m from antennas. Auteurs: Marat R. Ul’maskulov;Sergei A. Shunailov;Konstantin A. Sharypov;Michael I. Yalandin;Valery G. Shpak;Maxim S. Pedos;Sergei N. Rukin; Apparue dans: IEEE Transactions on Plasma Science Date publication: 10.-2017, volume: 45, issue:10, pages: 2623 - 2628 Editeur: IEEE Document complet vers site de l'éditeur
» Coiling Size Dependence of Group Delay Spread in Coupled Multicore Fibers Without Intentional Twisting
 Résumé:Coiling size dependence of group delay spread (GDS) in coupled multicore fibers (MCFs) without intentional twisting is investigated by using a coupled-wave theory. It is shown that the GDS does not simply decrease with increasing bending radius and the optimum coiling size to decrease GDS depends on a core-to-core distance of MCFs. It is also found that a coupled MCF with a trench-assisted profile is suitable for realizing lower GDS with higher spatial density compared with a coupled MCF with a step-index profile. Auteurs: Kunimasa Saitoh;Takeshi Fujisawa;Takanori Sato; Apparue dans: Journal of Lightwave Technology Date publication: 10.-2017, volume: 35, issue:20, pages: 4559 - 4566 Editeur: IEEE Document complet vers site de l'éditeur
» Collaborative Multi-Tier Caching in Heterogeneous Networks: Modeling, Analysis, and Design
 Résumé:To deal with the explosive growth in multimedia service requests in mobile networks, caching contents at the cells (base stations) is regarded as an effective emerging technique to reduce the duplicated transmissions of content downloads, while heterogeneous networks (HetNets) are regarded as an effective technique to increase the network capacity. Yet, the combination of content caching and HetNets for future networks (i.e., 5G) is still not well explored. In this paper, we propose an efficient collaborative multi-tier caching framework in Het-Nets. In particular, based on patterns of user requests, link capacities, heterogenous cache sizes, and the derived system topology, we focus on exploring the maximum capacity of the network infrastructure so as to offload the network traffic and support users’ content requests locally. Due to the NP-hardness of the complex multi-tier caching problem, we approximately decompose it into some subproblems that focus on the caching cooperation at different tiers by utilizing the derived system topology. Our proposed framework is low-complexity and distributed, and can be used for practical engineering implementation. Trace-based simulation results demonstrate the effectiveness of the proposed framework. Auteurs: Xiuhua Li;Xiaofei Wang;Keqiu Li;Zhu Han;Victor C. M. Leung; Apparue dans: IEEE Transactions on Wireless Communications Date publication: 10.-2017, volume: 16, issue:10, pages: 6926 - 6939 Editeur: IEEE Document complet vers site de l'éditeur
» Collaborators & Friends: The General Meeting Brings Us Together [Leader's Corner]
 Résumé:Presents highlights of the PES society 2017 General Meeting. Auteurs: Jessica Bian; Apparue dans: IEEE Power and Energy Magazine Date publication: 10.-2017, volume: 15, issue:5, pages: 10 - 10 Editeur: IEEE Document complet vers site de l'éditeur
» Colloidal CdSe Quantum Dots and PQT-12-Based Low-Temperature Self-Powered Hybrid Photodetector
 Résumé:In this letter, a novel dual junction self-powered hybrid photodetector is proposed using colloidal CdSe quantum dots (QDs) as an active layer (~50-nm thickness), and PQT-12 polymer as filter layer subsequently deposited on an ITO-coated glass substrate by the spin coating method. The colloidal CdSe QDs are deposited on the PQT-12 film at 80 °C, which is much smaller than the growth temperature (usually >300 °C) of the inorganic layer of other reported hybrid self-powered detectors. The Au metal dots are deposited on the CdSe QD layer for anode electrodes while the ITO acts as the cathode electrode of the device. Two asymmetric depletion widths formed at PQT-12/CdSe and Au/CdSe junctions at two sides of the active layer controls the operation of the proposed detector. The photodetector shows band-pass response over the visible spectrum with a sharp cutoff for higher wavelengths at ~610 nm. The maximum responsivity and detectivity of the self-powered photodetector are achieved to be ~3.3 mA/W and $5.4\times 10^{9}$ cmHz $^{1/2}\text{W}^{-1}$ , respectively, at a wavelength of ~420 nm under the optical power density of $\sim 130\mu \text{W}$ /cm2. The rise time and fall time of the device are found to be ~12.01 and ~15.32 ms, respectively. Auteurs: Hemant Kumar;Yogesh Kumar;Gopal Rawat;Chandan Kumar;Bratindranath Mukherjee;Bhola N. Pal;Satyabrata Jit; Apparue dans: IEEE Photonics Technology Letters Date publication: 10.-2017, volume: 29, issue:20, pages: 1715 - 1718 Editeur: IEEE Document complet vers site de l'éditeur
» Combination of SHE- and SHM-PWM Techniques for VSI DC-Link Current Harmonics Control in Railway Applications
 Résumé:The paper presents an innovative concept of applying a combination of well-known selective harmonic elimination (SHE) and selective harmonics mitigation (SHM) methods to shape a spectrum of catenary current harmonics, generated by a traction drive system equipped with a voltage source inverter. Application of this method allows for reducing distorting influence of a modern rolling stock supplied by a 3 kV dc catenary on the railway signaling, command, and control systems. The efficiency of the proposed method is independent of synchronization of a vehicle's inverters and of load balance of traction motors, which makes it more reliable than as it is proposed in the literature. Results of computer simulations were presented and compared with laboratory measurements. The obtained dc-link current spectrum using the proposed SHE/SHM method was compared with spectra received using synchronized and unsynchronized sinusoidal pulse-width modulations (SPWMs). Based on the conducted tests, it was shown that the proposed method of control, which was implemented in a laboratory drive system, is effective in reducing dc side current harmonics in a frequency range of 1300-3100 Hz, which is used by track circuits on railway lines, e.g., in Poland. The technique proposed by the authors allows taking into account any restrictions arising from the technical nature of low-frequency traction drives. Auteurs: Marcin Steczek;Piotr Chudzik;Adam Szeląg; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7666 - 7678 Editeur: IEEE Document complet vers site de l'éditeur
» Combined Pulse-Echo Ultrasound and Multispectral Optoacoustic Tomography With a Multi-Segment Detector Array
 Résumé:The high complementarity of ultrasonography and optoacoustic tomography has prompted the development of combined approaches that utilize the same transducer array for detecting both optoacoustic and pulse-echo ultrasound responses from tissues. Yet, due to the fundamentally different physical contrast and image formation mechanisms, the development of detection technology optimally suited for image acquisition in both modalities remains a major challenge. Herein, we introduce a multi-segment detector array approach incorporating array segments of linear and concave geometry to optimally support both ultrasound and optoacoustic image acquisition. The various image rendering strategies are tested and optimized in numerical simulations and calibrated tissue-mimicking phantom experiments. We subsequently demonstrate real-time hybrid optoacoustic ultrasound image acquisition in a healthy volunteer. The new approach enables the acquisition of high-quality anatomical data by both modalities complemented by functional information on blood oxygenation status provided by the multispectral optoacoustic tomography. Auteurs: Elena Merčep;Xosé Luís Deán-Ben;Daniel Razansky; Apparue dans: IEEE Transactions on Medical Imaging Date publication: 10.-2017, volume: 36, issue:10, pages: 2129 - 2137 Editeur: IEEE Document complet vers site de l'éditeur
» Command and Control for Multifunction Phased Array Radar
 Résumé:We discuss the challenge of managing the Multifunction Phased Array Radar (MPAR) timeline to satisfy the requirements of its multiple missions, with a particular focus on weather surveillance. This command and control (C2) function partitions the available scan time among these missions, exploits opportunities to service multiple missions simultaneously, and utilizes techniques for increasing scan rate where feasible. After reviewing the candidate MPAR architectures and relevant previous research, we describe a specific C2 framework that is consistent with a demonstrated active array architecture using overlapped subarrays to realize multiple, concurrent receive beams. Analysis of recently articulated requirements for near-airport and national-scale aircraft surveillance indicates that with this architecture, 40–60% of the MPAR scan timeline would be available for the high-fidelity weather observations currently provided by the Weather Service Radar (WSR-88D) network. We show that an appropriate use of subarray generated concurrent receive beams, in concert with previously documented, complementary techniques to increase the weather scan rate, could enable MPAR to perform full weather volume scans at a rate of 1 per minute. Published observing system simulation experiments, human-in-the-loop studies and radar-data assimilation experiments indicate that high-quality weather radar observations at this rate may significantly improve the lead time and reliability of severe weather warnings relative to current observation capabilities. Auteurs: Mark E. Weber;John Y. N. Cho;Henry G. Thomas; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5899 - 5912 Editeur: IEEE Document complet vers site de l'éditeur
» Comments on “Tracking Control of Robotic Manipulators With Uncertain Kinematics and Dynamics”
 Résumé:This letter considers the paper entitled “Tracking Control of Robotic Manipulators With Uncertain Kinematics and Dynamics” by B. Xiao, S. Yin, and O. Kaynak [IEEE Trans. Ind. Electron., vol. 63, no. 10, pp. 6439–6449, Oct. 2016], where the authors meant to provide an effective control for finite-time tracking of robot manipulators with both kinematic and dynamic uncertainties. This letter points out several flaws leading to the ineffectiveness of the main result in the paper. A correction is proposed. Auteurs: Yuxin Su;Chunhong Zheng;Paolo Mercorelli; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 8187 - 8189 Editeur: IEEE Document complet vers site de l'éditeur
 Résumé:A new effective interference-based capacity model was proposed for vehicular ad hoc network safety message broadcast scenario in M. Ni et al. (Commun. Lett., vol. 19, no. 4, pp. 621–624, Apr. 2015). This letter is a reconsideration and extension of the model in Ni et al.. First, we point out that the analysis in Ni et al. is incomplete and show a new derivation of the node transmission probability and the SIR distribution accounting for the impact of asynchronous timing of hidden terminals and all possible interference occurrence cases. Second, the analysis is extended to the derivation of other important quality of service metrics, such as packet reception probability, packet reception ratio, and transmission capacity. The proposed analysis is cross validated by MATLAB, PYTHON, and NS2 simulations. Auteurs: Xiaomin Ma;Hualin Lu;Jing Zhao;Yanbin Wang;Jingyu Li;Minming Ni; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2322 - 2325 Editeur: IEEE Document complet vers site de l'éditeur
» Communication With Imperfectly Shared Randomness
 Résumé:Communication complexity investigates the amount of communication needed for two or more players to determine some joint function of their private inputs. For many interesting functions, the communication complexity can be much smaller than basic information theoretic measures associated with the players’ inputs such as the input length, the entropy, or even the conditional entropy. Communication complexity of many functions reduces further when the players share randomness. Classical works studied the communication complexity of functions when the interacting players share randomness perfectly, i.e., they get identical copies of randomness from a common source. This paper considers the variant of this question when the players share randomness imperfectly, i.e., when they get noisy copies of the randomness produced by some common source. Our main result shows that any function that can be computed by a $k$ -bit protocol in the perfect sharing model has a $2^{k}$ -bit protocol in the setting of imperfectly shared randomness and such an exponential growth is necessary. Our upper bound relies on ideas from locality sensitive hashing, while lower bounds rely on hypercontractivity and a new invariance principle tailored for communication protocols. Auteurs: Clément L. Canonne;Venkatesan Guruswami;Raghu Meka;Madhu Sudan; Apparue dans: IEEE Transactions on Information Theory Date publication: 10.-2017, volume: 63, issue:10, pages: 6799 - 6818 Editeur: IEEE Document complet vers site de l'éditeur
» Compact and High-Gain UHF/UWB RFID Reader Antenna
 Résumé:A linearly polarized, dual-port, and dual-band radio frequency identification reader antenna is designed to simultaneously operate at ultrahigh frequency (UHF) and ultra-wideband bands for positioning systems. A hybrid design using patch and slot structures within a shared radiating aperture is proposed and demonstrated to achieve a high gain and wideband operation with a limited profile. The size of the total antenna is 200 mm $\times200$ mm $\times10$ mm. The measured impedance bandwidth of the UHF antenna ranges from 0.890 to 0.907 GHz with a minimum antenna gain of 9 dBi. The measured impedance bandwidth of the ultra-wideband antenna can cover the frequency band from 3 to 4.99 GHz with a minimum antenna gain of 9 dBi. The antenna gains near two WLAN bands are less than −15 dBi at 2.45 GHz and −5 dBi at 5.8 GHz, respectively. The mutual coupling between the two ports is less than −30 dB over the two bands. Auteurs: Jun Zhang;Zhongxiang Shen; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5002 - 5010 Editeur: IEEE Document complet vers site de l'éditeur
» Compact and Low-Cost Optical Fiber Respiratory Monitoring Sensor Based on Intensity Interrogation
 Résumé:In this paper, a plastic optical fiber sensor for respiratory monitoring purposes is presented. The sensor was integrated into a small, robust, and flexible package to be attached directly on a wide variety of positions on the upper body to monitor the motion induced by breathing. The sensor's operating principle is based on the variation in the intensity of the optical coupling intensity ratio between an input and a set of aligned output optical fibers. The system is demonstrated to be able to track the time-varying breathing signal when the sensor is placed at four different positions of the torso (including diaphragmatic and upper costal). The accuracy of the device is confirmed by a simultaneous comparison of the results with a commercial respiratory monitoring device. Measurement of breathing rate on four different healthy subjects showed excellent agreement with the measurement from the commercial respiratory monitoring device. The proposed fiber optic respiration sensor provides the advantages of being relatively low cost, compact, and simple in construction compared to the conventional existing respiration sensors. Auteurs: Wern Kam;Waleed Soliman Mohammed;Gabriel Leen;Mary O'Keeffe;Kieran O'Sullivan;Sinead O'Keeffe;Elfed Lewis; Apparue dans: Journal of Lightwave Technology Date publication: 10.-2017, volume: 35, issue:20, pages: 4567 - 4573 Editeur: IEEE Document complet vers site de l'éditeur
» Compact Differential Wideband Bandpass Filters Based on Half-Wavelength Lines
 Résumé:A compact differential wideband bandpass filter is proposed based on three half-wavelength transmission lines. The main advantages of small size and simple configuration are achieved. The improved design with two cascaded quarter-wavelength coupled lines can further improve the bandwidth of common-mode (CM) suppression and frequency selectivity. Two prototypes centered at 1.8 GHz with the size of $0.07\lambda _{g}^{2}(\lambda _{g}$ is the guided wavelength at the center frequency $f_{0}$ ) and $0.056\lambda _{g}^{2}$ are designed, fabricated, and measured. The measured results of Design I (Design II) exhibit the minimum insertion loss of 0.27 dB (0.6 dB), 3-dB fractional bandwidth of 57.8% (52%), and the bandwidth of 20-dB CM suppression of $0.67 f_{0}~(4.1 f_{0})$ . Auteurs: Jun Qiang;Jin Shi;Qinghua Cao;Zhidan Shen; Apparue dans: IEEE Microwave and Wireless Components Letters Date publication: 10.-2017, volume: 27, issue:10, pages: 906 - 908 Editeur: IEEE Document complet vers site de l'éditeur
» Compact On-Chip Bandpass Filter With Improved In-Band Flatness and Stopband Attenuation in 0.13- $\mu \text{m}$ (Bi)-CMOS Technology
 Résumé:In this letter, an on-chip miniaturized bandpass filter (BPF) is presented, which is based on a grounded center-tapped ring resonator (CTRR) with shunt capacitive loading. To analyze the principle of this design, a simple but effective equivalent circuit model is provided. Using this model, it is easy to show that the CTRR-based approach has a potential to generate two transmission poles within the passband. Compared with the conventional single-pole-based approach, this dual-pole design not only possesses a flexibility of controlling the passband width, but also has better flatness of insertion loss in the passband. In addition, this approach is able to significantly improve the stopband performance. To further demonstrate the feasibility of this approach in practice, the structure is implemented and fabricated in a commercial 0.13- $\mu \text{m}$ (Bi)-CMOS SiGe technology. The measured results show that the BPF has a center frequency at 33 GHz with a bandwidth of 42.4%. The minimum insertion loss is 2.6 dB, while the stopband rejection is maintained to be better than 20 dB beyond 58 GHz. The chip, excluding the pads, is very compact at only 0.03 mm2 ( $0.11\times0.28$ mm $^{{2}}{)}$ . Auteurs: Yang Yang;Hang Liu;Zhang Ju Hou;Xi Zhu;Eryk Dutkiewicz;Quan Xue; Apparue dans: IEEE Electron Device Letters Date publication: 10.-2017, volume: 38, issue:10, pages: 1359 - 1362 Editeur: IEEE Document complet vers site de l'éditeur
» Compact Polygonal Active-Mirror Laser With Composite Nd:YAG/YAG Gain Medium
 Résumé:A compact polygonal active-mirror (PAM) laser with composite Nd: YAG/YAG multithin-disk gain medium has been demonstrated with total internal reflection scheme. Five Nd:YAG thin disks with a neodymium concentration of 0.7 at.% and thickness of ∼0.2 mm were bonded to five different surfaces of a hexagonal YAG substrate. With no heat sink, output power of 1.03 W at 1064 nm and beam quality of M2 = 1.21 was obtained from a short-cavity oscillator based on the PAM architecture, under an absorption pump power of 2.30 W, with a slope efficiency and optical to optical efficiency of 55.8% and 44.8%, respectively. Auteurs: Yanzhong Chen;Ye Lang;Lifen Liao;Zhongwei Fan;Jianguo He;Guangyan Guo;Weiran Lin;Yunfeng Ma;Hongbo Zhang;Jian Zhang; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» Compact Wideband Dual Loop Coupler With High Power Handling Capability for Radar Applications
 Résumé:Couplers are widely used in microwave subsystems, especially for radar applications. They are used to extract a directive sample of the output signal of an RF source. Typically, a coupler consists of a main arm and a secondary arm connected via coupling section. For couplers used in radar applications, power handling is a limiting factor for designers. In addition, the coupling value must be kept a flat with a high directivity over the operating bandwidth of the coupler. In this letter, we provide designs for two compact loop couplers, operating in the frequency range of 1–2 GHz and 2–4 GHz. These designs have flat coupling of −60 dB and achieve matching below −22 dB. Auteurs: Shoukry I. Shams;Mahmoud Elsaadany;Gada Saad;Ahmed A. Kishk; Apparue dans: IEEE Microwave and Wireless Components Letters Date publication: 10.-2017, volume: 27, issue:10, pages: 900 - 902 Editeur: IEEE Document complet vers site de l'éditeur
» Compact, Frequency-Reconfigurable Filtenna With Sharply Defined Wideband and Continuously Tunable Narrowband States
 Résumé:A compact, frequency-reconfigurable filtenna with sharp out-of-band rejection in both its wideband and continuously tunable narrowband states is presented. It is intended for use in cognitive radio applications. The wideband state is the sensing state and operationally covers 2.35–4.98 GHz. The narrowband states are intended to cover communications within the 3.05–4.39 GHz range, which completely covers the Worldwide Interoperability for Microwave Access (WiMAX) band and the satellite communications C-band. A p-i-n diode is employed to switch between these wide and narrowband operational states. Two varactor diodes are used to shift the operational frequencies continuously among the narrowband states. The filtenna consists of a funnel-shaped monopole augmented with a reconfigurable filter; it has a compact electrical size: $0.235\lambda _{\textrm {L}} \times 0.392\lambda _{\textrm {L}}$ , where the wavelength $\lambda _{\textrm {L}}$ corresponds to the lower bound of its operational frequencies. The measured reflection coefficients, radiation patterns, and realized gains for both operational states are in good agreement with their simulated values. Auteurs: Ming-Chun Tang;Zheng Wen;Hao Wang;Mei Li;Richard W. Ziolkowski; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5026 - 5034 Editeur: IEEE Document complet vers site de l'éditeur
» Comparative Analysis on Conducted CM EMI Emission of Motor Drives: WBG Versus Si Devices
 Résumé:Silicon carbide (SiC) MOSFETs and gallium nitride (GaN) high-electron mobility transistors are perceived as future replacements for Si IGBTs and MOSFETs in medium- and low-voltage drives due to their low conduction and switching losses. However, it is widely believed that the already significant conducted common-mode (CM) electromagnetic interference (EMI) emission of motor drives will be further exacerbated by the high-speed switching operation of these new devices. Hence, this paper investigates and quantifies the increase in the conducted CM EMI emission of a pulse width modulation inverter-based motor drive when SiC and GaN devices are adopted. Through an analytical approach, the results reveal that the influence of dv/dt on the conducted CM emission is generally limited. On the other hand, the influence of switching frequency is more significant. Lab tests are also conducted to verify the analysis. Auteurs: Di Han;Silong Li;Yujiang Wu;Wooyoung Choi;Bulent Sarlioglu; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 8353 - 8363 Editeur: IEEE Document complet vers site de l'éditeur
» Comparative Study of the Biological Responses to Conventional Pulse and High-Frequency Monopolar Pulse Bursts
 Résumé:Given its nonthermal property and other advantages, irreversible electroporation (IRE) has quickly translated into clinical applications. An increasing number of clinical cases using IRE have also revealed crucial issues. The uneven distribution of the electric field caused by the heterogeneity of biological tissues has not been completely and effectively addressed to date. The use of high-frequency monopolar pulse bursts (HFMPBs) is expected to solve this problem. The high-frequency content of the HFMPB is used to ensure the uniform distribution of the electric field in the tissue. A temperature increase similar to that of the conventional pulse method does not cause thermal damage and results in a killing effect similar to that of the conventional technique. Meanwhile, the subpulse has a pulse duration of 1– $100~\mu \text{s}$ , which remains unexplored and may induce new cell responses. This paper analyzes the HFMPB based on the frequency domain and infers that the cell death pathways under this pulse induce necrosis and other processes, such as apoptosis. The phosphatidylserine externalization rate had a peak value at a different inner frequency of HFMPB when the electric field was 1 kV/cm for melanoma cells. This new type of pulse is expected to solve the problem of the uneven distribution of the electric field without altering the cell killing effect. If this effect is also verified in tissue ablation, these new types of pulses will promote the clinical application of IRE. Auteurs: Chenguo Yao;Yajun Zhao;Yan Mi;Shoulong Dong;Yanpeng Lv;Hongmei Liu;Xiaoyu Wang;Liling Tang; Apparue dans: IEEE Transactions on Plasma Science Date publication: 10.-2017, volume: 45, issue:10, pages: 2629 - 2638 Editeur: IEEE Document complet vers site de l'éditeur
» Comparison of Elevation Change Detection Methods From ICESat Altimetry Over the Greenland Ice Sheet
 Résumé:Estimation of the surface elevation change of the Greenland Ice Sheet (GrIS) is essential for understanding its response to recent and future climate change. Laser measurements from the NASA’s Ice, Cloud, and land Elevation Satellite (ICESat) created altimetric surveys of GrIS surface elevations over the 2003–2009 operational period of the mission. This paper compares four change detection methods using Release 634 ICESat laser altimetry data: repeat tracks (RTs), crossovers (XOs), overlapping footprints (OFPs), and triangulated irregular networks (TINs). All four methods begin with a consistently edited data set and yield estimates of volumetric loss of ice from the GrIS ranging from −193 to −269 km3/yr. Using a uniform approach for quantifying uncertainties, we find that volume change rates at the drainage system scale from the four methods can be reconciled within 1- $\sigma$ uncertainties in just 5 of 19 drainage systems. Ice-sheet-wide volume change estimates from the four methods cannot be reconciled within 1- $\sigma$ uncertainties. Our volume change estimates lie within the range of previously published estimates, highlighting that the choice of method plays a dominant role in the scatter of volume change estimates. We find that for much of the GrIS, the OFP and TIN methods yield the lowest volume change uncertainties because of their superior spatial distribution of elevation change rate estimates. However, the RT and XO methods offer inherent advantages, and the future work to combine the elevation change detection methods to produce better estimates is warranted. Auteurs: Denis Felikson;Timothy J. Urban;Brian C. Gunter;Nadège Pie;Hamish D. Pritchard;Robert Harpold;Bob E. Schutz; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5494 - 5505 Editeur: IEEE Document complet vers site de l'éditeur
» Comparison of Fabrication Techniques for Flexible UHF RFID Tag Antennas [Wireless Corner]
 Résumé:The astonishing boom of radio-frequency identification (RFID) technology is stimulating plenty of new RFID-based industrial applications. Consequently, in the very near future, an almost unlimited number of RFID tags could be embedded into manufactured goods of various shapes, assets, and machineries to enable their communication abilities. As a result, prototyping techniques of RFID tags on flexible substrates are becoming more crucial. In this article, four different techniques suitable for prototyping flexible tags are briefly explained and tested from many points of view: ease of use, processing time, cost, tag sensitivity, radiation pattern, impedance, and robustness of the realized prototype. Characterization methods and experimental setups are presented, and two tag layouts, one commercial and one appositely designed, are used to compare the different techniques. Auteurs: Riccardo Colella;Almudena Rivadeneyra;Alberto J. Palma;Luciano Tarricone;Luis Fermin Capitan-Vallvey;Luca Catarinucci;Jose F. Salmeron; Apparue dans: IEEE Antennas and Propagation Magazine Date publication: 10.-2017, volume: 59, issue:5, pages: 159 - 168 Editeur: IEEE Document complet vers site de l'éditeur
» Comparison of High-Speed Electrical Motors for a Turbo Circulator Application
 Résumé:This paper presents an analysis of three different electrical machine topologies for a turbo circulator application. The electrical machines are designed to operate with 6 kW output power at 120 000 r/min. This paper demonstrates the design aspects of one solid rotor squirrel cage induction motor and two permanent magnet synchronous machines. The machines are compared using electromagnetic, thermal, and mechanical analyses. The benefits and disadvantages of each topology under study are discussed. For other high-speed applications presented, a comparative approach helps in selecting the suitable electrical machine topology by analyzing the performance criteria discussed. The prototype construction of one of the topologies is analyzed. Auteurs: Nikita Uzhegov;Jan Barta;Jiri Kurfürst;Cestmir Ondrusek;Juha Pyrhönen; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4308 - 4317 Editeur: IEEE Document complet vers site de l'éditeur
» Comparison of Two-Individual Current Control and Vector Space Decomposition Control for Dual Three-Phase PMSM
 Résumé:The relationship between the two-individual current control and the vector space decomposition (VSD) control for a dual three-phase permanent magnet synchronous machine (PMSM) is investigated in this paper. It is found that the VSD control is more flexible in controlling the fundamental current in $\alpha \beta$ subplane and the fifth, seventh current harmonics in $z_{1}z_{2}$ subplane with different proportional and integral (PI) gains, while the two-individual current control is comparable with the VSD control in having the same PI gains in the $\alpha \beta$ and $z_{1}z_{2}$ subplanes. It is also found that the two-individual current control may have potential instability issues due to the mutual coupling between the two sets of three-phase windings. If the mutual coupling between the two sets is weak to some extent, then the two-individual current control could have the same dynamic performance as the VSD control without the stability issues. Experiments are conducted on a prototype dual three-phase PMSM to validate the theoretical analysis. Auteurs: Yashan Hu;Z. Q. Zhu;Milijana Odavic; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4483 - 4492 Editeur: IEEE Document complet vers site de l'éditeur
» Compete or Collaborate: Architectures for Collaborative DASH Video Over Future Networks
 Résumé:Dynamic adaptive streaming over HTTP (DASH) clients compete with each other over one or more bottleneck links in a network, which results in fluctuations in TCP throughput and QoE, QoE unfairness among clients, and underutilization of the network capacity. We propose centralized and distributed architectures for collaboration between network service provider (NSP), video service provider (VSP), and users (DASH clients) to provide NSP-managed or VSP-managed DASH services over software-defined networks (SDN) with quality-of-service (QoS) reserved network slices. We show that QoS reservation alone is not sufficient to overcome QoE fluctuations per client and unfairness between heterogeneous video clients, and clients also need to employ TCP receive-window adaptation knowing their fair-share bitrate. To this effect, we propose two collaborative streaming service models to inform clients about their fair-share bitrates. We first present an NSP-managed service model with centralized collaboration between the NSP, VSP, and the users, where a traffic engineering manager at the NSP assigns a fair-share bitrate to each DASH client. We then present a VSP-managed service model with centralized or distributed collaboration architectures, where in the former the VSP determines the fair-share bitrate for each client over a reserved network slice and in the latter a group of DASH clients sharing a reserved network slice collaborate among themselves. In the novel distributed collaboration framework, collaboration groups are identified by the VSP, and clients within a group share critical parameters with each other so that each client can estimate its fair-share bitrate. Experimental results demonstrate that collaboration rather than competition between clients not only helps them achieve a smooth goodput near their fair-share bitrate, but also improves the total goodput over the reserved slice. Auteurs: Kadir Tolga Bagci;Kemal Emrecan Sahin;A. Murat Tekalp; Apparue dans: IEEE Transactions on Multimedia Date publication: 10.-2017, volume: 19, issue:10, pages: 2152 - 2165 Editeur: IEEE Document complet vers site de l'éditeur
» Complete Electrical Arc Hazard Classification System and Its Application
 Résumé:The standard for electrical safety in the workplace, National Fire Protection Association 70E, and relevant Occupational Safety and Health Act electrical safety standards evolved in the U.S. over the past 40 years to address the hazards of 60-Hz power that are faced primarily by electricians, linemen, and others performing facility and utility work. This leaves a substantial gap in the management of other types of electrical hazards including battery banks, dc power systems, capacitor banks, and solar power systems. Although many of these systems are fed by 50/60-Hz energy, we find substantial use of electrical energy, and the use of capacitors, inductors, batteries, solar, and radiofrequency (RF) power. The electrical hazards of these forms of electricity and their systems are different than for 50/60 Hz ac power. At the IEEE Electrical Safety Workshop in 2009, we presented a comprehensive approach to classifying the electrical shock hazards of all types of electricity, including various waveforms and various types of sources of electrical energy. That paper introduced a new comprehensive electrical shock hazard classification system that used a combination of voltage, shock current available, fault current available, power, energy, and waveform to classify all forms of electrical hazards with a focus on the shock hazard. That paper was based on research conducted over the past 100 years and on decades of experience. This paper continues the effort in understanding and managing all forms of injury from all forms of electricity with the introduction of a comprehensive approach to classifying all forms of injury from the electrical arc, including thermal, blast pressure, hearing, radiation, and shrapnel injury. The general term “arc” is divided into the arc, arc flash, and arc blast as a first subdivision of type of source of injury. Then, the parameters of voltage, short-circuit current, energy, waveform, gap distance, gap geom- try, enclosure geometry, and time are used to choose various approaches to analysis. Recent efforts to understand, model, and estimate injury for these types of systems are reviewed. Most of the focus to understand and predict injury for dc, capacitor, solar, and RF arc hazards has been only in the past 10 years. A comprehensive approach to analyzing all forms of injury from all forms of electrical arcs is presented. Auteurs: Lloyd B. Gordon;Kyle D. Carr;Nicole Graham; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 5078 - 5087 Editeur: IEEE Document complet vers site de l'éditeur
» Completion Time Analysis of Wafer Lots in Single-Armed Cluster Tools With Parallel Processing Modules
 Résumé:We analyze the completion time of wafer lots in single-armed cluster tools with parallel processing modules (PMs) by considering the lot switching operation. To effectively assign wafer lots and dispatch overhead hoist transports (OHTs) to manufacturing tools, it is crucial to obtain the completion time of wafer lots. However, estimating the completion time is not straightforward, due to the concurrent processing of two consecutive wafer lots during lot switching operation, which often increases wafer sojourn times in PMs. In this paper, we derive closed-form expressions of the completion time of wafer lots in single-armed cluster tools with parallel PMs. We assume that the robot unloads wafers in the order of their loading sequence. We then experimentally show that the formulas derived can be used even when processing time variation exists or another robot task sequence, which is of first-in first-out (FIFO), is assumed.Note to Practitioners—Due to the larger wafer size and circuit width reduction, cluster tools often perform the lot switching operation with each pair of consecutive wafer lots. In addition, since most tools are operated with parallel chambers, concurrent processing with two different wafer lots occurs frequently. Such transient periods in operating tools make it hard to estimate the completion time of wafer lots. In this paper, we derive closed-form expressions to obtain the completion time of wafer lots in single-armed cluster tools with parallel chambers. We further show that the formulas can be used with processing time variation or the FIFO rule. With the formulas, OHTs can be sent just-in-time to tools to load or unload wafer cassettes, and wafer lots can be assigned while minimizing the transient periods. In addition, the estimated completion time can be utilized in the planning and scheduling of wafer fabrication processes. Auteurs: Jun-Ho Lee;Hyun-Jung Kim; Apparue dans: IEEE Transactions on Automation Science and Engineering Date publication: 10.-2017, volume: 14, issue:4, pages: 1622 - 1633 Editeur: IEEE Document complet vers site de l'éditeur
» Complexity Reduction by Modified Scale-Space Construction in SIFT Generation Optimized for a Mobile GPU
 Résumé:Scale-invariant feature transform (SIFT) is one of the most widely used local features for computer vision in mobile devices. A mobile graphic processing unit (GPU) is often used to run computer-vision applications using SIFT features, but the performance in such a case is not powerful enough to generate SIFT features in real time. This paper proposes an efficient scheme to optimize the SIFT algorithm for a mobile GPU. It analyzes the conventional scale-space construction step in the SIFT generation, finding that reducing the size of the Gaussian filter and the scale-space image leads to a significant speedup with only a slight degradation of the quality of the features. Based on this observation, the SIFT algorithm is modified and implemented for real-time execution. Additional optimization techniques are employed for a further speedup by efficiently utilizing both the CPU and the GPU in a mobile processor. The proposed SIFT generation scheme achieves a processing speed of 28.30 frames/s for an image with a resolution of $1280 \times 720$ running on a Galaxy S5 LTE-A device, thereby gaining a speedup by the factors of 114.78 and 4.53 over CPU- and GPU-only implementations, respectively. Auteurs: Chulhee Lee;Chae Eun Rhee;Hyuk-Jae Lee; Apparue dans: IEEE Transactions on Circuits and Systems for Video Technology Date publication: 10.-2017, volume: 27, issue:10, pages: 2246 - 2259 Editeur: IEEE Document complet vers site de l'éditeur
» Composability Verification of Multi-Service Workflows in a Policy-Driven Cloud Computing Environment
 Résumé:The emergence of cloud computing infrastructure and Semantic Web technologies has created unprecedented opportunities for composing large-scale business processes and workflow-based applications that span multiple organizational domains. A key challenge related to composition of such multi-organizational business processes and workflows is posed by the security and access control policies of the underlying organizational domains. In this paper, we propose a framework for verifying secure composability of distributed workflows in an autonomous multi-domain environment. The objective of workflow composability verification is to ensure that all the users or processes executing the designated workflow tasks conform to the time-dependent security policy specifications of all collaborating domains. A key aspect of such verification is to determine the time-dependent schedulability of distributed workflows, assumed to be invoked on a recurrent basis. We use a two-step approach for verifying secure workflow composability. In the first step, a distributed workflow is decomposed into domain-specific projected workflows and is verified for conformance with the respective domain's security and access control policy. In the second step, the cross-domain dependencies amongst the workflow tasks performed by different collaborating domains are verified. Auteurs: Basit Shafiq;Sameera Ghayyur;Ammar Masood;Zahid Pervaiz;Abdulrahman Almutairi;Farrukh Khan;Arif Ghafoor; Apparue dans: IEEE Transactions on Dependable and Secure Computing Date publication: 10.-2017, volume: 14, issue:5, pages: 478 - 493 Editeur: IEEE Document complet vers site de l'éditeur
» Compression-Based Compressed Sensing
 Résumé:Modern compression codes exploit signals’ complex structures to encode them very efficiently. On the other hand, compressed sensing algorithms recover “structured” signals from their under-determined set of linear measurements. Currently, there is a noticeable gap between the types of structures used in the area of compressed sensing and those employed by state-of-the-art compression codes. Recent results in the literature on deterministic signals aim at bridging this gap through devising compressed sensing decoders that employ compression codes. This paper focuses on structured stochastic processes and studies application of lossy compression codes to compressed sensing of such signals. The performance of the formerly proposed compressible signal pursuit (CSP) optimization is studied in this stochastic setting. It is proved that in the low-distortion regime, as the blocklength grows to infinity, the CSP optimization reliably and robustly recovers $n$ instances of a stationary process from its random linear measurements as long as $n$ is slightly more than $n$ times the rate-distortion dimension (RDD) of the source. It is also shown that under some regularity conditions, the RDD of a stationary process is equal to its information dimension. This connection establishes the optimality of CSP at least for memoryless stationary sources, which have known fundamental limits. Finally, it is shown that CSP combined by a family of universal variable-length fixed-distortion compression codes yields a family of universal compressed sensing recovery algorithms. Auteurs: Farideh E. Rezagah;Shirin Jalali;Elza Erkip;H. Vincent Poor; Apparue dans: IEEE Transactions on Information Theory Date publication: 10.-2017, volume: 63, issue:10, pages: 6735 - 6752 Editeur: IEEE Document complet vers site de l'éditeur
» Compressive Sensing as Applied to Inverse Problems for Imaging: Theory, Applications, Current Trends, and Open Challenges.
 Résumé:Compressive sensing (CS) is currently one the most active research fields in information engineering and science. The flexibility, robustness, accuracy, effectiveness, and sound theory behind such a paradigm have motivated a great interest in developing and applying CS to many domains, including inverse scattering. Unfortunately, electromagnetic imaging problems have some unique theoretical features that prevent a straightforward exploitation of CS tools. Therefore, suitable CS-based strategies must be considered in such a framework. Auteurs: Giacomo Oliveri;Marco Salucci;Nicola Anselmi;Andrea Massa; Apparue dans: IEEE Antennas and Propagation Magazine Date publication: 10.-2017, volume: 59, issue:5, pages: 34 - 46 Editeur: IEEE Document complet vers site de l'éditeur
» Compressive Sensing Techniques for mm-Wave Nondestructive Testing of Composite Panels
 Résumé:This paper presents imaging results from measurements of an industrially manufactured composite test panel, utilizing two introduced algorithms for data postprocessing. The system employs a planar near-field scanning setup for characterizing defects in composite panels in the 50–67-GHz band, and can be considered as a complementary diagnostic tool for nondestructive testing purposes. The introduced algorithms are based on the reconstruction of the illuminating source at the transmitter, enabling a separation of the sampled signal with respect to the location of its potential sources, the scatterers within the device under test or the transmitter. For the second algorithm, an $L_{1}$ -minimization problem formulation is introduced that enables compressive sensing techniques to be adapted for image retrieval. The algorithms are benchmarked against a more conventional imaging technique, based on the Fourier transform, and it is seen that the complete imaging system provides increased dynamic range, improved resolution, and reduced measurement time by removal of a reference measurement. Moreover, the system provides stable image quality over a range of frequencies. Auteurs: Jakob Helander;Andreas Ericsson;Mats Gustafsson;Torleif Martin;Daniel Sjöberg;Christer Larsson; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5523 - 5531 Editeur: IEEE Document complet vers site de l'éditeur
» Computable Delay Margins for Adaptive Systems With State Variables Accessible
 Résumé:Robust adaptive control of plants whose state variables are accessible in the presence of an input time delay is established in this paper. It is shown that a standard model reference adaptive controller modified with projection ensures global boundedness of the overall adaptive system for a range of nonzero delays. The upper bound of such delays, that is, the delay margin, is explicitly defined and can be computed a priori. Auteurs: Heather S. Hussain;Yildiray Yildiz;Megumi Matsutani;Anuradha M. Annaswamy;Eugene Lavretsky; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5039 - 5054 Editeur: IEEE Document complet vers site de l'éditeur
» Concealment of Chaos Time-Delay Signature Through Phase-Conjugate Feedback and Chaos Optical Injection
 Résumé:In this paper, we numerically demonstrate that the concealment of time-delay signature (TDS) can be readily achieved via the combined mechanism of phase-conjugate feedback (PCF) and chaotic optical injection. To show the potential advantages of the proposed scheme, its counterpart, i.e., a slave semiconductor laser (SSL) subjected to chaotic optical injection from a master semiconductor laser (MSL) with conventional optical feedback (COF) is studied in parallel. In particular, we consider a fair situation where the MSL in both PCF and COF shows a comparable peak value in the autocorrelation function computed from the intensity time series. Our simulations uncover that combining the mechanism of PCF and chaotic optical injection is beneficial for TDS concealment in the SSL. To better understand this, the effects of some control parameters including injection and feedback are comparably studied. The results further prove that, as the injection or feedback parameters are varied, the proposed PCF-system always exhibits weaker autocorrelation around the feedback delay value when compared to the COF-system. In the meantime, the former system allows for larger bandwidth and, thus, paves way for important applications to secure communication and random-number generation. Auteurs: Penghua Mu;Wei Pan;Lianshan Yan;Bin Luo;Xihua Zou; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» Concise Planning and Filtering: Hardness and Algorithms
 Résumé:Motivated by circumstances with severe computational resource limits (e.g., settings with strong constraints on memory or communication), this paper addresses the problem of concisely representing and processing information for estimation and planning tasks. In this paper, conciseness is a measure of explicit representational complexity: for filtering, we are concerned with maintaining as little state as possible to perform a given task; for the planning case, we wish to generate the plan graph (or policy graph) with the fewest vertices that is correct and also complete. We present hardness results showing that both filtering and planning are NP-hard to perform in an optimally concise way, and that the related decision problems are NP-complete. We also describe algorithms for filter reduction and concise planning, for which these hardness results justify the potentially suboptimal output. The filter-reduction algorithm accepts as input an arbitrary combinatorial filter, expressed as a transition graph, and outputs an equivalent filter that uses fewer I-states to complete the same filtering task. The planning algorithm, using the filter-reduction algorithm as a subroutine, generates concise plans for planning problems that may involve both nondeterminism and partial observability. Both algorithms are governed by parameters that encode tradeoffs between computational efficiency and solution quality. We describe implementation of both algorithms and present a series of experiments evaluating their effectiveness. Auteurs: Jason M. O’Kane;Dylan A. Shell; Apparue dans: IEEE Transactions on Automation Science and Engineering Date publication: 10.-2017, volume: 14, issue:4, pages: 1666 - 1681 Editeur: IEEE Document complet vers site de l'éditeur
» Concurrent Control of Mobility and Communication in Multirobot Systems
 Résumé:We develop a hybrid system architecture that enables a team of mobile robots to complete a task in a complex environment by self-organizing into a multihop ad hoc network and solving the concurrent communication and mobility problem. The proposed system consists of a two-layer feedback loop. An outer loop performs infrequent global coordination and a local inner loop determines motion and communication variables. This system provides the lightweight coordination and responsiveness of decentralized systems while avoiding local minima. This allows a team to complete a task in complex environments while maintaining desired end-to-end data rates. The behavior of the system is evaluated in experiments that demonstrate: 1) successful task completion in complex environments; 2) achievement of equal or greater end-to-end data rates as compared to a centralized system; and 3) robustness to unexpected events such as motion restriction. Auteurs: James Stephan;Jonathan Fink;Vijay Kumar;Alejandro Ribeiro; Apparue dans: IEEE Transactions on Robotics Date publication: 10.-2017, volume: 33, issue:5, pages: 1248 - 1254 Editeur: IEEE Document complet vers site de l'éditeur
» Conditions for Almost Global Attractivity of a Synchronous Generator Connected to an Infinite Bus
 Résumé:Conditions for existence and global attractivity of the equilibria of a realistic model of a synchronous generator with constant field current connected to an infinite bus are derived. First, necessary and sufficient conditions for existence and uniqueness of equilibrium points are provided. Then, sufficient conditions for local asymptotic stability and almost global attractivity of one of these equilibria are given. The analysis is carried out by employing a new Lyapunov-like function to establish convergence of bounded trajectories, while the latter is proven using the powerful theoretical framework of cell structures pioneered by Leonov and Noldus. The efficiency of the derived sufficient conditions is illustrated via extensive numerical experiments based on two benchmark examples taken from the literature. Auteurs: Nikita Barabanov;Johannes Schiffer;Romeo Ortega;Denis Efimov; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 4905 - 4916 Editeur: IEEE Document complet vers site de l'éditeur
» Conductor Surface Conditions Effects on the Ion-Flow Field of Long-Term Operating Conductors of the HVDC Transmission Line
 Résumé:The influence of conductor surface conditions of new and aged conductors on ground-level resultant electric field and ion current density is analyzed in this paper. The surface roughness and morphology of conductors are measured and analyzed by 3-D phase shift Micro-Xam (MicroXAM-3D) and scanning electron microscopy. Calculations are made using the upstream finite-element-finite difference method for the corona cage model to obtain the influence of surface conditions on the ion-flow field, consequently, changing the resulting electric field and ion current density. An indoor corona cage platform is build up to check the impact of surface conditions on the ground-level resultant electric field and ion current density in the laboratory. Considering the aging characteristics of the conductor surface, a typical ±800 kV ultra-high voltage direct current transmission line is analyzed. The calculated results show that compared with the new conductor, the electric field and ion current density of the long-term operation conductors increase very significantly. Auteurs: Yong Yi;Chuyan Zhang;Liming Wang;Zhengying Chen; Apparue dans: IEEE Transactions on Power Delivery Date publication: 10.-2017, volume: 32, issue:5, pages: 2171 - 2178 Editeur: IEEE Document complet vers site de l'éditeur
» Conformational Space Sampling Method Using Multi-Subpopulation Differential Evolution for De novo Protein Structure Prediction
 Résumé:Protein structure prediction can be considered as a multimodal optimization problem for sampling the protein conformational space associated with an extremely complex energy landscape. To address this problem, a conformational space sampling method using multi-subpopulation differential evolution, MDE, is proposed. MDE first devotes to generate given numbers of concerned modal under the ultrafast shape recognition-based modal identification protocol, which regards each individual as one modal at beginning. Then, differential evolution is used for keeping the preserved modal survival in the evolution process. Meanwhile, a local descent direction used to sample along with is constructed based on the abstract convex underestimate technique for modal enhancement, which could enhance the ability of sampling in the region with lower energy. Through the sampling process of evolution, several certain clusters contain a series of conformations in proportion to the energy score will be obtained. Representative conformations in the generated clusters can be directly picked out as decoy conformations for further refinement with no extra clustering operation needs. A total of 20 target proteins are tested, in which ten target proteins are tested for comparison with Rosetta and three evolutionary algorithms, and ten easy/hard target proteins in CASP 11 are tested for further verifying the effectiveness of MDE. Test results show strong sampling ability that MDE holds, and near-native conformations can be effectively obtained. Auteurs: Xiao-Hu Hao;Gui-Jun Zhang;Xiao-Gen Zhou; Apparue dans: IEEE Transactions on NanoBioscience Date publication: 10.-2017, volume: 16, issue:7, pages: 618 - 633 Editeur: IEEE Document complet vers site de l'éditeur
» Consensus With Output Saturations
 Résumé:This paper considers a standard consensus algorithm under output saturations. In this case, the global consensus cannot be realized due to the existence of stable equilibrium points that do not belong to the consensus manifold. Therefore, this paper investigates necessary and sufficient initial conditions for the achievement of consensus that characterize an exact domain of attraction. Specifically, this paper considers single-integrator agents with both fixed and time-varying undirected graphs. Then, we show that the consensus will be achieved if and only if the average of the initial states is within the minimum saturation level. Auteurs: Young-Hun Lim;Hyo-Sung Ahn; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5388 - 5395 Editeur: IEEE Document complet vers site de l'éditeur
» Considering Backhaul [Book\Software Reviews]
 Résumé:This book offers a comprehensive guide to the subject of microwave backhaul. Design information on this subject is sparse, and it is not easy to collect and interpret. This fact was the driving force behind the creation of this book, which focuses on the electronics of backhaul and describes in detail all the subsystems responsible for transforming the information signal that comes from baseband processing into an electromagnetic wave traveling through the air. Electronics for Microwave Backhaul presents an overview of the evolution of the electronics for microwave radios, from their initial development to present implementations and future trends. The authors have stayed abreast of current real-world industry products and present many real-world solutions to the design issues. Auteurs: James Chu; Apparue dans: IEEE Microwave Magazine Date publication: 10.-2017, volume: 18, issue:6, pages: 125 - 126 Editeur: IEEE Document complet vers site de l'éditeur
» Constrained Dynamic Systems: Generalized Modeling and State Estimation
 Résumé:Due to physical laws or mathematical properties the states of some dynamic systems satisfy certain constraints, and taking advantage of such constraints generally will produce more accurate system models. This paper is concerned with dynamic modeling and state estimation of equality constrained systems. First, an effective framework for constrained dynamic modeling is proposed by which equality constraints and an original dynamics are optimally fused. In particular, modeling of linear and quadratic equality constrained dynamic systems is systematically investigated. Meanwhile, the effects of the original dynamics on the constructed dynamic model are analyzed. Next, properties of the constrained state estimation are presented, and in particular, the constrained minimum mean square error (CMMSE) estimator is proposed and its differences from the conventional constrained estimators are illustrated. Finally, the proposed modeling is assessed on benchmark scenarios of road-confined vehicle tracking. Simulation results demonstrate that the proposed CMMSE estimator outperforms the conventional constrained ones. Auteurs: Linfeng Xu;X. Rong Li;Yan Liang;Zhansheng Duan; Apparue dans: IEEE Transactions on Aerospace and Electronic Systems Date publication: 10.-2017, volume: 53, issue:5, pages: 2594 - 2609 Editeur: IEEE Document complet vers site de l'éditeur
» Constructions of Binary Sequence Pairs of Period $3p$ With Optimal Three-Level Correlation
 Résumé:In this letter, we present a new generalized cyclotomic method over $Z_{3p}$ based on the Chinese remainder theorem and the cyclotomic classes of order 2. Two new families of binary sequence pairs of period $N=3p$ with optimal three-level correlation values are constructed by utilizing these new generalized cyclotomic classes, where $p>3$ is an odd prime. All the constructed binary sequence pairs have optimal correlation values {−3, 1} or {−1, 3}. Auteurs: Xiumin Shen;Yanguo Jia;Xiaofei Song; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2150 - 2153 Editeur: IEEE Document complet vers site de l'éditeur
» Contact Force Monitoring and Its Application in Vacuum Circuit Breakers
 Résumé:Condition monitoring of circuit-breaker (CB) operating mechanisms is one the most important aspects of predictive maintenance. This paper proposes a contact force monitoring scheme for 10 ~ 35-kV vacuum CB. With specially designed force sensors and a signal-processing method, we can accurately find the instants of contact touch and separation. With the indirectly measured contact touch-and-separation instants, we can measure the opening speed, closing speed, and open gap over the travel of each phase. The accuracy of our online monitoring scheme is compared with the conventional offline methods that can directly obtain the instants of contact touch and separation by measuring the connectivity of the contacts. The results show that the accuracy of the scheme proposed in this paper is satisfactory and it can meet the engineering requirements of online condition monitoring of CBs. By introducing a set of new force sensors, some additional information that is useful for overall condition assessment of CB operating mechanism can also be extracted; this will help us to find new ways to improve our CB condition monitoring systems. Auteurs: Jianzhong Tang;Shisong Lu;Jingwei Xie;Zhengmin Cheng; Apparue dans: IEEE Transactions on Power Delivery Date publication: 10.-2017, volume: 32, issue:5, pages: 2154 - 2161 Editeur: IEEE Document complet vers site de l'éditeur
» Contactless Current Measurement for Enclosed Multiconductor Systems Based on Sensor Array
 Résumé:How to measure ac currents in a bundle of inaccessible, enclosed conductors has been a challenging problem but with many potential applications. This paper presents a method to solve the problem using an array of magnetic field sensors. The proposed method consists of two novel ideas. The first idea is to use an off-site calibration method to establish sensor parameters including sensing position and angle, which provides more accurate sensor parameter estimation than their nominal values. The second idea is to “measure” (i.e., calculate) conductor currents and positions based on the sensed magnetic fields and preestablished sensor parameters. This process is simplified since the sensor information is obtained by the first idea. Both calibration and measurement tasks are formulated as nonlinear least square problems and solved efficiently. The proposed method is demonstrated for the cases involving ideal three-conductor system and practical residential service cable enclosed in a plastic conduit. The method has the potential for contactless current measurement of Romex cables and overhead distribution lines. Auteurs: Guangchao Geng;Juncheng Wang;Kun-Long Chen;Wilsun Xu; Apparue dans: IEEE Transactions on Instrumentation and Measurement Date publication: 10.-2017, volume: 66, issue:10, pages: 2627 - 2637 Editeur: IEEE Document complet vers site de l'éditeur
» Content Placement for Wireless Cooperative Caching Helpers: A Tradeoff Between Cooperative Gain and Content Diversity Gain
 Résumé:Depending on what and how caching helpers cache content in their finite storage, the caching helpers can offer either a content diversity gain by serving diverse content or a cooperative gain by jointly transmitting the same content. This paper identifies a tradeoff between the content diversity gain and the cooperative gain according to content placements and proposes a probabilistic content placement to optimally balance the tradeoff. Using stochastic geometry, we quantify this tradeoff by deriving the cache hit rate and the rate coverage probability. To efficiently control the tradeoff, we determine the near-optimal caching probabilities that maximize the average content delivery success probability with the cooperative caching helpers. Our analysis and numerical results reveal that our proposed content placement outperforms the conventional caching schemes, such as caching with uniform probabilities, caching the most popular contents, and caching the content maximizing the cache hit, in terms of the average content delivery success probability. Auteurs: Seong Ho Chae;Tony Q. S. Quek;Wan Choi; Apparue dans: IEEE Transactions on Wireless Communications Date publication: 10.-2017, volume: 16, issue:10, pages: 6795 - 6807 Editeur: IEEE Document complet vers site de l'éditeur
» Context-Aware Architecture for Probabilistic Voting-based Filtering Scheme in Sensor Networks
 Résumé:Wireless sensor networks are widely deployed and implicitly characterized by stringent energy and computation constraints. Sensor nodes are vulnerable to false positive and false negative attacks that inject false data through compromised nodes. Such attacks cause false alarms with energy drain and information loss. Although several en-route filtering schemes have been designed to detect the attacks, they focus on saving energy through early filtering or continuous delivery of data in accordance with verification records; they cannot exclude compromised nodes. In this paper, we propose a scheme that effectively identifies the compromised nodes and copes with new attacks using a context-aware architecture. In addition, the proposed scheme improves the security strength and energy efficiency of the network. Simulation results validate that the proposed scheme provides energy savings of up to 45 percent and allows fewer attack successes than the existing scheme. Auteurs: Su Man Nam;Tae Ho Cho; Apparue dans: IEEE Transactions on Mobile Computing Date publication: 10.-2017, volume: 16, issue:10, pages: 2751 - 2763 Editeur: IEEE Document complet vers site de l'éditeur
» Continuous and Singular Micromagnetic Configurations
 Résumé:Up to the present time [1965], only magnetic configurations that are continuous in the micromagnetic sense have been described in the literature. The consequences of this continuity restriction on possible types of magnetization reversal processes have received no attention. These consequences are discussed here. It is also shown that micromagnetic discontinuities are allowed theoretically. In particular, a micromagnetically singular point may exist that is the zero-dimensional analog of the two-dimensional wall and the one-dimensional Bloch or Néel line of magnetic domain theory. Auteurs: Ernst Feldtkeller; Apparue dans: IEEE Transactions on Magnetics Date publication: 10.-2017, volume: 53, issue:10, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» Control and Emulation of Small Wind Turbines Using Torque Estimators
 Résumé:Soft-stall control of small wind turbines is a method to protect the generation system and/or load from excessive wind speeds and wind gusts without discontinuing power generation. Soft-stall can be activated due to an excess of the power and/or torque/current. This paper proposes a method to improve the existing soft-stall methods for over torque/current protection using a turbine torque estimator. In addition, this paper also proposes two methods to emulate the wind turbine inertia without communications between the load drive (wind turbine emulator) and the generation system controller. This will allow the evaluation of the proposed methods in working conditions. Auteurs: Juan M. Guerrero;Carlos Lumbreras;David Díaz Reigosa;Pablo Garcia;Fernando Briz; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4863 - 4876 Editeur: IEEE Document complet vers site de l'éditeur
» Control Design for Disturbance Rejection in the Presence of Uncertain Delays
 Résumé:This paper is concerned with control of processes with uncertain delays for disturbance rejection. The effect of the uncertain delays on the stability is studied. First, the method to compute the maximum uncertain delay that a given controller can tolerate is described. Second, in the case of PI/PID controller, all of the admissible controller parameters stabilizing a system with uncertain but bounded delays are determined. Meanwhile, we propose a simple method to construct the parameter space satisfying a given robustness index for the nominal model. In the admissible regions satisfying various objectives, the global optimum controller is achieved for disturbance rejection in the presence of uncertain delay. As a result, the MIGO ( -constrained Integral Gain Optimization) method is revisited in the case of uncertain delay, and the rule of selecting the value of maximum sensitivity function is proposed in terms of the bound on the uncertain delay. Two simulation examples and an experiment are given to demonstrate the effectiveness and advantage of the proposed method. Auteurs: Qibing Jin;Qie Liu;Biao Huang; Apparue dans: IEEE Transactions on Automation Science and Engineering Date publication: 10.-2017, volume: 14, issue:4, pages: 1570 - 1581 Editeur: IEEE Document complet vers site de l'éditeur
» Control Method of Double Inverter Fed Wound Machine for Minimizing Copper Loss in Maximized Operating Area
 Résumé:A double inverter fed wound machine (DFWM) needs two inverters on the rotor as well as the stator side. This scheme gives more freedom to operation of an electric machine and improves the output power capability and the efficiency, but its control method becomes more complex because the number of control variables and the operating constraints increase. This paper deals with a control method of DFWM for minimizing the copper loss in maximized operating area. The possible operation area considering all constraints of currents, voltages, and flux is analyzed on the stator currents plane to maximize the operating area. For the minimum copper loss operation in the operating area, different modes are defined and the optimal currents are determined in each mode. Also, the optimal current selection algorithm is proposed to achieve the torque control using the optimal currents. The simulation and experimental results about wound machines are presented to show the feasibility of the proposed control method. Auteurs: Yongsu Han;Jung-Ik Ha; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7700 - 7710 Editeur: IEEE Document complet vers site de l'éditeur
» Control of a City Road Network: Distributed Exact Verification of Traffic Safety
 Résumé:A least-restrictive supervisor for vehicle collision avoidance is a control algorithm that can detect an unsafe maneuver by a set of human-driven or autonomous vehicles, intervening with a corrective action only when needed to avoid a collision. It can help prevent collisions, and facilitate coexistence of autonomous and human-driven vehicles. Such an algorithm is based on a formal verification problem which, unfortunately, is known to be NP-hard in many cases of interest, for instance at traffic intersections. Here, we propose a strategy to dynamically decompose the formal verification problem of a large road network, exploiting vehicle dynamics and the constraints induced by road topology to separate nonconflicting vehicles. We split the global problem into smaller and treatable subproblems, while still allowing to compute an exact solution. We illustrate our results on three different scenarios. Auteurs: Alessandro Colombo;Gabriel Rodrigues de Campos;Fabio Della Rossa; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 4933 - 4948 Editeur: IEEE Document complet vers site de l'éditeur
» Control of Buffer-Induced Current Collapse in AlGaN/GaN HEMTs Using SiNx Deposition
 Résumé:The stoichiometry of low-pressure chemical vapor deposition SiNx surface passivation is shown to change vertical conductivity at the top of the epitaxial stack in GaN-on-Si power high-electron mobility transistors (HEMTs). This changes the charge stored in the carbon-doped GaN layer during high-voltage operation, and allows direct control of buffer-related current collapse in HEMTs. Substrate bias ramps are used to identify the changes in C:GaN charge trapping and vertical leakage. Channel length dependence indicates a lateral conductivity in the C:GaN with a localized increase in vertical conductivity under the ohmic contacts. An optimum SiNx recipe is identified which simultaneously delivers low current collapse and low drain leakage. Auteurs: William M. Waller;Mark Gajda;Saurabh Pandey;Johan J. T. M. Donkers;David Calton;Jeroen Croon;Jan Šonský;Michael J. Uren;Martin Kuball; Apparue dans: IEEE Transactions on Electron Devices Date publication: 10.-2017, volume: 64, issue:10, pages: 4044 - 4049 Editeur: IEEE Document complet vers site de l'éditeur
» Control of Junction Temperature and Its Rate of Change at Thermal Boundaries via Precise Loss Manipulation
 Résumé:To optimize the lifetime of switching power semiconductors, this paper presents a methodology to control power device junction temperature ${T_j}$ and its change during power cycles $\Delta {T_j}$ at thermal boundaries. This paper proposes a supervisory state machine to interrupt nominal system-level control only when temperature bounds are exceeded, and coordinates smooth transitions as ${T_j}(k)$ and $\Delta {T_j}(k)$ approach their respective boundaries. To ensure that thermal states are regulated via precise and independent modulation of conduction and switching loss elements, decoupling methods are proposed. Also proposed is a $\Delta {T_j}$ control law that closes a control loop on the rate of change state ${\bar{\dot{T}}_j}$ , and introduces active thermal capacitance and conductance into the closed-loop thermal system dynamics. Experimental evaluation of the proposed system illustrates well damped ${T_j}(k)$ and $\Delta {T_j}(k)$ responses, and gradual adjustment of the manipulated inputs switching frequency and duty ratio. Finally, comparison with a current limit-based ${T_j}$ regulation method illustrates how the proposed system allows power converters to push harder against their thermal limits. Auteurs: Timothy Allen Polom;Boru Wang;Robert D. Lorenz; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4796 - 4806 Editeur: IEEE Document complet vers site de l'éditeur
» Control Scheme for Open-Ended Induction Motor Drives With a Floating Capacitor Bridge Over a Wide Speed Range
 Résumé:An electric drive for high-speed applications is analyzed in this paper. The drive consists of a dual two-level inverter with a floating bridge, fed by a single voltage source, and a three-phase induction motor with open-ended stator windings. The floating bridge compensates the reactive power of the motor, so that the main inverter operates at unity power factor and fully exploits its current capability. The constant power speed range of the motor can be significantly extended depending on the dc-link voltage of the floating inverter. The details of the control system are examined and the feasibility of an electric drive is experimentally assessed. Auteurs: Michele Mengoni;Albino Amerise;Luca Zarri;Angelo Tani;Giovanni Serra;Domenico Casadei; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4504 - 4514 Editeur: IEEE Document complet vers site de l'éditeur
» Control Strategy for a Modified Cascade Multilevel Inverter With Dual DC Source for Enhanced Drivetrain Operation
 Résumé:This paper presents a new control strategy for a modified cascade multilevel inverter used in drivetrain operations. The proposed inverter is a three-phase bridge with its dc link fed by a dc source (battery), and each phase series-connected to an H-bridge fed with a floating dc source (ultracapacitor). To exploit the potentials of the inverter for enhanced drivetrain performance, a sophisticated yet efficient modulation method is proposed to optimize energy transfer between the dc sources and with the load (induction motor) during typical operations, and to minimize switching losses and harmonics distortion. Detailed analysis of the proposed control method is presented, which is supported by experimental verifications. Auteurs: Maciej S. Bendyk;Patrick Chi-Kwong Luk;Mohammed H. Alkhafaji; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4655 - 4664 Editeur: IEEE Document complet vers site de l'éditeur
» Controllability of Multiagent Networks With Antagonistic Interactions
 Résumé:This paper addresses the controllability of a class of antagonistic multiagent networks with both positive and negative edges. All the agents of the multiagent network run a consensus algorithm using a signed Laplacian. Based on the generalized equitable partition, we propose a graph-theoretic characterization of an upper bound on the controllable subspace. Then, we provide a necessary condition for the controllability of the system and give an algorithm to compute the partition. Furthermore, we prove that for a structurally balanced network, the controllability is equivalent to that of the corresponding all-positive network, if the leaders are chosen from the same vertex set. Several examples are given to illustrate these results. Auteurs: Chao Sun;Guoqiang Hu;Lihua Xie; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5457 - 5462 Editeur: IEEE Document complet vers site de l'éditeur
» Controllable Rotations of Spiraling Elliptic Beams in Anisotropic Linear Media
 Résumé:We study the rotation properties of spiraling elliptic beams in the anisotropy media. Based on the Collins formula, we obtain the exact analytical solution of the spiraling elliptic beams carrying the orbital angular momentum (OAM) to the paraxial wave equation. It is found that the rotation property is closely relevant to the OAM, which can be controlled by the linear anisotropy of media. For an anisotropic media such as the uniaxial crystal, the rotation velocity of spiraling elliptic beams at the output can be controlled only by changing the direction of the optic axis of the uniaxial crystal. Depending on the anisotropy parameter, two rotation modes are predicted for the spiraling elliptic beam. For small anisotropy parameter, the rotation direction of the spiraling elliptic beam is inverted at a certain propagation distance. When the anisotropy parameter is large enough, the invertion of the rotation direction disappears. The results are potentially useful in controlling the optical beams. Auteurs: Guo Liang;Tingjian Jia;Zhanmei Ren; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» Controllable Unidirectional Emission With Double-Resonant Plasmonic Antenna
 Résumé:A double-resonant metal–insulator–metal (MIM) optical antenna is theoretically proposed to control the emission directivity of a dipolar emitter. The nanoantenna consists of an in-plane side-by-side assembling metallic nanobar dimer on the top and a metallic nanoplate on the bottom, separated by a dielectric spacer. Unidirectional and enhanced emission of the emitter is wavelength dependent. It is controllable by changing the phase differences of constituting elements of the antenna, induced by the double magnetic resonances at different wavelengths. The results can be potentially used in near-field sample detection, solar cell, and single-photon source. Auteurs: Fei Liu;Shengyin Ye;Kailiang Zhang;Guangjun Ren; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 10 Editeur: IEEE Document complet vers site de l'éditeur
» Controlled Kink Effect in a Novel High-Voltage LDMOS Transistor by Creating Local Minimum in Energy Band Diagram
 Résumé:A new technique to control the kink effect in the high-voltage lateral double-diffused MOSFET (LDMOS) is presented in this paper. This technique produces a local minimum in the band diagram of the proposed structure, which causes the lower barrier height for the holes from the channel to the source region. So, the produced excess holes during the impact ionization process in the channel are reduced significantly. We have called the proposed structure as local minimum energy band LDMOS (LMEB-LDMOS) transistor. The LMEB-LDMOS structure contains modified source and drain regions. The modified source region creates a local minimum in the energy band diagram for absorbing the excess holes, and the modified drain region causes high breakdown voltage (462 V) and low specific on-resistance ( $5.1~\text {m}\Omega \cdot ~\text {cm}^{{{{2}}}})$ . Also, the drift region with lower doping density than drain is deleted in LMEB-LDMOS transistor. The simulation with 2-D ATLAS simulator shows that the proposed structure improves the device performance. Auteurs: Mahsa Mehrad;Meysam Zareiee;Ali A. Orouji; Apparue dans: IEEE Transactions on Electron Devices Date publication: 10.-2017, volume: 64, issue:10, pages: 4213 - 4218 Editeur: IEEE Document complet vers site de l'éditeur
» Controlled Voltage Breakdown in Disconnector Contact System for VFTO Mitigation in Gas-Insulated Switchgear (GIS)
 Résumé:Several methods have been proposed and investigated so far on mitigation of very fast transient overvoltages (VFTO) in gas-insulated switchgear (GIS). The state-of-the-art methods are primarily based on dissipation of the energy associated with electromagnetic waves that the VFTO originate from and are composed of. Present paper reports on an alternative concept of VFTO mitigation based on the principle of controlling voltage conditions preceding voltage breakdown in SF6 gas that leads to VFTO generation. The paper introduces different control algorithms and shows how the algorithms can limit VFTO maximum value and total number of voltage breakdowns during operation of the GIS disconnector. The concept is applied for mitigation of VFTO in ultra-high voltage GIS. As the study case, an 1100 kV test set-up is used as recently reported for Wuhan (China) GIS station, with the disconnector characteristics obtained from 1100 kV development tests. Auteurs: Marcin Szewczyk;Maciej Kuniewski; Apparue dans: IEEE Transactions on Power Delivery Date publication: 10.-2017, volume: 32, issue:5, pages: 2360 - 2366 Editeur: IEEE Document complet vers site de l'éditeur
» Convergence Rate of Distributed ADMM Over Networks
 Résumé:We propose a new distributed algorithm based on alternating direction method of multipliers (ADMM) to minimize sum of locally known convex functions using communication over a network. This optimization problem emerges in many applications in distributed machine learning and statistical estimation. Our algorithm allows for a general choice of the communication weight matrix, which is used to combine the iterates at different nodes. We show that when functions are convex, both the objective function values and the feasibility violation converge with rate $O(1/T)$, where $T$ is the number of iterations. We then show that when functions are strongly convex and have Lipschitz continuous gradients, the sequence generated by our algorithm converges linearly to the optimal solution. In particular, an $\epsilon$-optimal solution can be computed with $O\left(\sqrt{\kappa _f} \log (1/\epsilon) \right)$ iterations, where $\kappa _f$ is the condition number of the problem. Our analysis highlights the effect of network and communication weights on the convergence rate through degrees of the nodes, the smallest nonzero eigenvalue, and operator norm of the communication matrix. Auteurs: Ali Makhdoumi;Asuman Ozdaglar; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5082 - 5095 Editeur: IEEE Document complet vers site de l'éditeur
» Convex Distributed Controller Synthesis for Interconnected Heterogeneous Subsystems Via Virtual Normal Interconnection Matrices
 Résumé:Based on a previously introduced framework for distributed controller synthesis, in this note a novel transformation of interconnection matrices is proposed that enables to consider arbitrary, time-varying and directed interaction topologies. It represents any interconnection as a virtual interconnection matrix that has the property of being normal, i.e., that guarantees the existence of a unitary diagonalizing transformation, which admits to decompose the synthesis problem in terms of the entire interconnected system into problems of subsystem scale, which can then be solved by standard convex multiplier-based gain-scheduling synthesis methods with complexity in the order of a single subsystem. When compared with a method from the literature, the method shows superior performance in both a numerical example and the leader-follower formation control problem of nonlinear quadrocopter models. Auteurs: C. Hoffmann;H. Werner; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5337 - 5342 Editeur: IEEE Document complet vers site de l'éditeur
» Cooperative Modulation Classification for Multipath Fading Channels via Expectation-Maximization
 Résumé:In this paper, we investigate the cooperative modulation classification problem under multipath scenarios with blind channel information. Multipath channels cause severe degradation on the modulation classification performance, which has not yet been thoroughly solved in the existing literature. To address this issue, a likelihood-based classifier using the expectation-maximization algorithm is proposed, which is capable of finding the maximum likelihood estimates of unknown parameters in a tractable way. Furthermore, to evaluate the upper bound performance of the proposed algorithm, the Cramér–Rao lower bounds of the joint estimates of unknown parameters are derived. Extensive simulations show that the classification performance of the proposed algorithm with good initialization scheme is close to the performance upper bound in the high signal-to-noise ratio region. The results also demonstrate that the proposed algorithm provides significant performance improvement in the multipath channels compared with conventional approaches. Auteurs: Jingwen Zhang;Danijela Cabric;Fanggang Wang;Zhangdui Zhong; Apparue dans: IEEE Transactions on Wireless Communications Date publication: 10.-2017, volume: 16, issue:10, pages: 6698 - 6711 Editeur: IEEE Document complet vers site de l'éditeur
» Cooperative Raman Spectroscopy for Real-Time In Vivo Nano-Biosensing
 Résumé:In the last few decades, the development of miniature biological sensors that can detect and measure different phenomena at the nanoscale has led to transformative disease diagnosis and treatment techniques. Among others, biofunctional Raman nanoparticles have been utilized in vitro and in vivo for multiplexed diagnosis and detection of different biological agents. However, existing solutions require the use of bulky lasers to excite the nanoparticles and similarly bulky and expensive spectrometers to measure the scattered Raman signals, which limit the practicality and applications of this nano-biosensing technique. In addition, due to the high path loss of the intra-body environment, the received signals are usually very weak, which hampers the accuracy of the measurements. In this paper, the concept of cooperative Raman spectrum reconstruction for real-time in vivo nano-biosensing is presented for the first time. The fundamental idea is to replace the single excitation and measurement points (i.e., the laser and the spectrometer, respectively) by a network of interconnected nano-devices that can simultaneously excite and measure nano-biosensing particles. More specifically, in the proposed system, a large number of nanosensors jointly and distributively collect the Raman response of nano-biofunctional nanoparticles (NBPs) travelling through the blood vessels. This paper presents a detailed description of the sensing system and, more importantly, proves its feasibility, by utilizing the accurate models of optical signal propagation in intra-body environment and low-complexity estimation algorithms. The numerical results show that with a certain density of NBPs, the reconstructed Raman spectrum can be recovered and utilized to accurately extract the targeting intra-body information. Auteurs: Hongzhi Guo;Josep Miquel Jornet;Qiaoqiang Gan;Zhi Sun; Apparue dans: IEEE Transactions on NanoBioscience Date publication: 10.-2017, volume: 16, issue:7, pages: 571 - 584 Editeur: IEEE Document complet vers site de l'éditeur
» Coprime Factors Model Reduction of Spatially Distributed LTV Systems Over Arbitrary Graphs
 Résumé:This technical note is on the model reduction of distributed systems formed by discrete-time, linear time-varying, heterogeneous subsystems interconnected over arbitrary directed graphs and subjected to communication latency. We give two procedures to construct a strongly stable coprime factorization for a strongly stabilizable and strongly detectable system. One of the procedures ensures the contractiveness of the resulting factorization. Then, we apply the structure-preserving balanced truncation method for distributed systems. We illustrate the proposed methods through an example. Auteurs: Dany Abou Jaoude;Mazen Farhood; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5254 - 5261 Editeur: IEEE Document complet vers site de l'éditeur
» Copula-Based Joint Statistical Model for Polarimetric Features and Its Application in PolSAR Image Classification
 Résumé:Polarimetric features are essential to polarimetric synthetic aperture radar (PolSAR) image classification for their better physical understanding of terrain targets. The designed classifiers often achieve better performance via feature combination. However, the simply combination of polarimetric features cannot fully represent the information in PolSAR data, and the statistics of polarimetric features are not extensively studied. In this paper, we propose a joint statistical model for polarimetric features derived from the covariance matrix. The model is based on copula for multivariate distribution modeling and alpha-stable distribution for marginal probability density function estimations. We denote such model by CoAS. The proposed model has several advantages. First, the model is designed for real-valued polarimetric features, which avoids the complex matrix operations associated with the covariance and coherency matrices. Second, these features consist of amplitudes, correlation magnitudes, and phase differences between polarization channels. They efficiently encode information in PolSAR data, which lends itself to interpretability of results in the PolSAR context. Third, the CoAS model takes advantage of both copula and the alpha-stable distribution, which makes it general and flexible to construct the joint statistical model accounting for dependence between features. Finally, a supervised Markovian classification scheme based on the proposed CoAS model is presented. The classification results on several PolSAR data sets validate the efficacy of CoAS in PolSAR image modeling and classification. The proposed CoAS-based classifiers yield superior performance, especially in building areas. The overall accuracies are higher by 5%–10%, compared with other benchmark statistical model-based classification techniques. Auteurs: Hao Dong;Xin Xu;Haigang Sui;Feng Xu;Junyi Liu; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5777 - 5789 Editeur: IEEE Document complet vers site de l'éditeur
» Correction to “The Generalized Stochastic Likelihood Decoder: Random Coding and Expurgated Bounds” [Aug 17 5039-5051]
 Résumé:The purpose of this paper is to handle a gap that was found in the proof of Theorem 2 in the paper “The generalized stochastic likelihood decoder: random coding and expurgated bounds.” Auteurs: Neri Merhav; Apparue dans: IEEE Transactions on Information Theory Date publication: 10.-2017, volume: 63, issue:10, pages: 6827 - 6829 Editeur: IEEE Document complet vers site de l'éditeur
» Corrections to “JANUS-Based Services for Operationally Relevant Underwater Applications” [ IEEE J. Ocean. Eng., 2017, DOI: 10.1109/JOE.2017.2722018]
 Résumé: Auteurs: R. Petroccia;J. Alves;G. Zappa; Apparue dans: IEEE Journal of Oceanic Engineering Date publication: 10.-2017, volume: 42, issue:4, pages: 1162 - 1162 Editeur: IEEE Document complet vers site de l'éditeur
» Corrections to “Density of Traps at the Insulator/III-N Interface of GaN Heterostructure Field-Effect Transistors Obtained by Gated Hall Measurements”
 Résumé:In the above paper [1], equation 5 should read (1) $dV_{B} ={d\left ({ {q\Delta n} }\right )} / {C_{B} }$ Equation 6 should read(2) $D_{it} \left ({ {E_{f} +{q\Delta n}/ {C_{B} }} }\right )\approx \frac {C_{B} C_{I} }{q^{2}}\left [{ {\left ({ {\frac {d\left ({ {q\Delta n} }\right )}{dV_{G} }} }\right )^{-1}-\frac {1}{C_{HF} }} }\right ]$ Auteurs: Shlomo Mehari;Arkady Gavrilov;Moshe Eizenberg;Dan Ritter; Apparue dans: IEEE Electron Device Letters Date publication: 10.-2017, volume: 38, issue:10, pages: 1504 - 1504 Editeur: IEEE Document complet vers site de l'éditeur
» Corrections to “On-Chip Investigation of Phase Noise in Monolithically Integrated Gain-Switched Lasers”
 Résumé:In the above letter equations (2) and (6) are incorrect due to an additional $S$ present within the bracketed term. Auteurs: Justin K. Alexander;Padraic E. Morrissey;Ludovic Caro;Mohamad Dernaika;Niall P. Kelly;Frank H. Peters; Apparue dans: IEEE Photonics Technology Letters Date publication: 10.-2017, volume: 29, issue:20, pages: 1755 - 1755 Editeur: IEEE Document complet vers site de l'éditeur
» Correlated Random Bit Generation Using Chaotic Semiconductor Lasers Under Unidirectional Optical Injection
 Résumé:Correlated random bit generation is investigated using three optically injected chaotic semiconductor lasers. Based on a rate-equation model, a continuous-wave injection first perturbs a common laser into chaos. The common laser then optically injects a pair of response lasers through a public channel unidirectionally. The two response lasers of identical parameters are synchronized. Their chaotic emissions are digitized in yielding correlated random bit streams. As the scheme advantageously involves no feedback loops, the output bits contain no undesirable time-delay information artifacts. Security is ensured as the response lasers produce bits that cannot be extracted using the information in the public channel alone. Output bit streams are generated at a tunable rate of up to about 2 Gbps with randomness verified by a test suite of the National Institute of Standards and Technology. The streams are correlated with a low bit error ratio of less than 4$\%$ , which is sensitive to parameter mismatch between the response lasers. Auteurs: Xiao-Zhou Li;Song-Sui Li;Sze-Chun Chan; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 11 Editeur: IEEE Document complet vers site de l'éditeur
» Correlation of Gate Capacitance with Drive Current and Transconductance in Negative Capacitance Ge PFETs
 Résumé:Correlation of gate capacitance ${C} _{G}$ with drive current ${I} _{\textsf {DS}}$ and transconductance ${G} _{m}$ in negative capacitance (NC) Ge pFETs is first investigated. Hysteresis-free NC Ge pFETs integrated with 4.5-nm HZO achieving the improved ${I} _{\textsf {DS}}$ and ${G} _{m}$ over the control devices are fabricated. A peak in the ${C} _{G}$ versus gate voltage curve is demonstrated in the NC Ge pFET, indicating the NC effect induced by HZO film. It is observed that ${I} _{\textsf {DS}}$ and ${G} _{m}$ of the NC transistors are enhanced as the ${C} _{G}$ peak gets increased. This is attributed to the fact that, as the device operates in the NC region, both ${C} _{G}$ and internal gate voltage amplification are proportional to ${C} _{\textsf {FE}}$ /( ${C} _{\textsf {FE}}+{C}_{\textsf {MOS}}$ ), where ${C} _{\textsf {FE}}$ and ${C} _{\textsf {MOS}}$ are the NC of HZO and the MOS capacitance of the device, respectively. Auteurs: Jing Li;Jiuren Zhou;Genquan Han;Yan Liu;Yue Peng;Jincheng Zhang;Qing-Qing Sun;David Wei Zhang;Yue Hao; Apparue dans: IEEE Electron Device Letters Date publication: 10.-2017, volume: 38, issue:10, pages: 1500 - 1503 Editeur: IEEE Document complet vers site de l'éditeur
» Cost Effective Laser Structuration of Optical Waveguides on Thin Glass Interposer
 Résumé:In order to enhance electro–optical system-in-package capabilities for silicon photonics, a cost effective fabrication process for optical waveguides integration on thin glass substrate interposer is demonstrated. First, a femtosecond laser ablation coupled with a hydrofluoric acid etching is developed to create microgrooves at the glass surface. Second, a dry film lamination followed by chemical mechanical planarization is achieved to define surface optical waveguides by filling the microchannels. Physical characterizations of the fabricated waveguides are performed using optical and scanning electron microscopy. Finally, optical mode profile and loss characterizations confirm the optical functionality of waveguides which prove to be multimodal at 1550 nm. Auteurs: Jean-Marc Boucaud;Folly-Eli Ayi-Yovo;Quentin Hivin;Matthieu Berthomé;Cédric Durand;Frédéric Gianesello;Davide Bucci;Guillaume Ducournau;Jean-François Robillard;Jean-Emmanuel Broquin;Emmanuel Dubois; Apparue dans: Journal of Lightwave Technology Date publication: 10.-2017, volume: 35, issue:20, pages: 4445 - 4450 Editeur: IEEE Document complet vers site de l'éditeur
» Coupled Parametric Effects on Magnetic Fields of Eddy-Current Induced in Non-Ferrous Metal Plate for Simultaneous Estimation of Geometrical Parameters and Electrical Conductivity
 Résumé:Illustrated with a magnetic field based eddy-current (EC) sensor which utilizes an anisotropic magneto-resistive sensor to directly measure the magnetic flux density (MFD) generated by the EC induced in a non-ferrous metal plate, this paper presents a material-independent method for multi-objective estimation of the plate geometrical parameters and/or electrical conductivity using frequency response analysis. The model, which agrees well with a 2-D axis-symmetric finite-element analysis, relates the measured (EC-generated) MFD to three dimensionless parameters (skin depth, plate thickness, and sensor-plate distance) normalized relative to a specified coil design. Data in the material-independent model that provides the basis to investigate the parametric effects on measured MFD can be regrouped in 2-D maps for simultaneously measuring any two of the three parameters. Experimental measurements were conducted on three different materials (Aluminum, Titanium, and Titanium alloy) with different thicknesses and sensor-plate distances between 1 and 5 mm operating in the frequency range from 100 Hz to 42.8 kHz. Experimental results show that the maximum difference between the analytically computed and experimental data is in the order of 5%, and demonstrate that the method has the capability of simultaneously measuring two unknowns out of three geometrical and/or material properties using a material-independent 2-D map. Auteurs: Kok-Meng Lee;Chun-Yeon Lin;Bingjie Hao;Min Li; Apparue dans: IEEE Transactions on Magnetics Date publication: 10.-2017, volume: 53, issue:10, pages: 1 - 9 Editeur: IEEE Document complet vers site de l'éditeur
» Coupling Characteristics of Selective-Infiltration-Based Locally Tapered Photonic Crystal Fiber
 Résumé:We have proposed and experimentally demonstrated a novel compound structure based on selectively infiltrating of a local tapered photonic crystal fiber (TPCF). Theoretical and experimental investigations indicate that tapering photonic crystal fiber (PCF) can change the material refractive index (RI) of silica core, and the RI change can be revealed and proved to influence the effective RI curve of the PCF core mode, which results in the shifting of the phase matching point. Moreover, strong coupling can occur in the infiltrated TPCF due to the increased overlap integral of the involved coupled modes. As application, the proposed configuration based on TPCF has huge potential use in microfluidic, RI, and dual-parameter sensing with high sensitivity, such as ultrahigh strain sensitivity of –139.78 nm/N (–167.74 pm/μϵ). Auteurs: Hu Liang;Zhi Wang;Yange Liu;Hongye Li;Hongwei Zhang; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 7 Editeur: IEEE Document complet vers site de l'éditeur
» Coupling Matrix Synthesis of Microwave Differentiators
 Résumé:This letter presents a new design of microwave differentiators using coupled-resonator network. It is synthesized using coupling matrix techniques in the low-pass domain and subsequently transformed and implemented in the bandpass domain. Two numerical examples and one experimental validation are provided to illustrate the approach, which finally validates the proposed approach. Auteurs: Qingfeng Zhang;Fen Xia;Ge Zhang;Yifan Chen; Apparue dans: IEEE Microwave and Wireless Components Letters Date publication: 10.-2017, volume: 27, issue:10, pages: 879 - 881 Editeur: IEEE Document complet vers site de l'éditeur
» Coupling Quality [Enigmas, etc.]
 Résumé:Various puzzles, games, humorous definitions, or mathematical that should engage the interest of readers. Auteurs: Takashi Ohira; Apparue dans: IEEE Microwave Magazine Date publication: 10.-2017, volume: 18, issue:6, pages: 154 - 154 Editeur: IEEE Document complet vers site de l'éditeur
» Covariance Matrix Estimation for Broadband Underwater Noise
 Résumé:In this paper, a technique is presented for frequency-smoothing the sample covariance matrix observed at the output of a set of elements or beams so as to obtain a frequency-smoothed estimate of the broadband noise covariance matrix due to underwater noise. The smoothing technique is based on a linear model that is derived through analysis of the delay-domain cross covariance of the ambient noise observed by a pair of beams or omnidirectional hydrophones. A simple and robust least squares fitting algorithm allows for extraction of a frequency-smoothed broadband noise covariance estimate even in the presence of narrowband energy. Simulated passive sonar examples demonstrate the validity and utility of the estimate. Possible applications include adaptive beamforming and measuring the vertical/horizontal directionality of diffuse broadband ambient noise sources such as wind and rain. Auteurs: Ryan J. Pirkl;Jason M. Aughenbaugh; Apparue dans: IEEE Journal of Oceanic Engineering Date publication: 10.-2017, volume: 42, issue:4, pages: 936 - 947 Editeur: IEEE Document complet vers site de l'éditeur
» Cross-Entropy Method for Electromagnetic Optimization With Constraints and Mixed Variables
 Résumé:An elegant and simple approach is presented for electromagnetic (EM) optimizations, especially when mixed variables and/or constraints are involved. In mixed-variable optimization, some variables are continuous (can take any value within a range) and others are discrete (can take only values from a database). An example constraint is when the total length of a device under optimization is specified. Our approach can handle such optimization problems and is based on an abstract probabilistic evolutionary optimization algorithm, called the cross-entropy (CE) method. We believe that this is the first application of CE with full-wave EM simulations. A quick performance benchmarking on two test functions was performed to compare convergence of CE and two other established optimization algorithms. Then, the advantages of the CE method when simultaneously optimizing a mix of discrete and continuous variables and imposing geometric constraints are illustrated. Finally, six resonant cavity antennas (RCAs) were optimized, and one was prototyped and tested to verify predicted results. This one-layer-superstrate RCA prototype has a measured peak directivity of 17.6 dBi with a 3 dB directivity bandwidth of 51% and lower sidelobes, outperforming all such prototypes in the literature. Auteurs: Maria Kovaleva;David Bulger;Basit Ali Zeb;Karu P. Esselle; Apparue dans: IEEE Transactions on Antennas and Propagation Date publication: 10.-2017, volume: 65, issue:10, pages: 5532 - 5540 Editeur: IEEE Document complet vers site de l'éditeur
» Crosstalk Analysis of Heterogeneous Multicore Fibers Using Coupled-Mode Theory
 Résumé:Intercore crosstalk of heterogeneous multicore fiber is investigated based on coupled-mode theory. Random twisting model is used for estimating the crosstalk. The crosstalk of two kinds of fibers: triangular lattice 30-core fiber with four kinds of cores and square lattice 32-core fiber with two kinds of cores is investigated both theoretically and experimentally. Unlike previous study, measured crosstalk for all the combinations of cores for both fibers is in good agreement with calculated values with single correlation length, showing the validity of the theoretical model used here. Auteurs: Takeshi Fujisawa;Yoshimichi Amma;Yusuke Sasaki;Shoichiro Matsuo;Kazuhiko Aikawa;Kunimasa Saitoh;Masanori Koshiba; Apparue dans: IEEE Photonics Journal Date publication: 10.-2017, volume: 9, issue:5, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» Crowdsourcing Sensing to Smartphones: A Randomized Auction Approach
 Résumé:Crowdsourcing to mobile users has emerged as a compelling paradigm for collecting sensing data over a vast area for various monitoring applications. It is of paramount importance for such crowdsourcing paradigm to provide effective incentive mechanisms. State-of-the-art auction mechanisms for crowdsourcing to mobile users are typically deterministic in the sense that for a given sensing job from a crowdsourcer, only a small set of smartphones are selected to perform sensing tasks and the rest are not selected. One apparent disadvantage of such deterministic auction mechanisms is that the diversity with respect to the sensing job is reduced. As a consequence, the quality of the collected sensing data is also decreased. This is due to failure to exploit the intrinsic advantage of the large set of diverse mobile users in a mobile crowdsourcing network. In this paper, we propose a randomized combinatorial auction mechanism for the social cost minimization problem, which is proven to be NP-hard. We design an approximate task allocation algorithm that is near optimal with polynomial-time complexity and use it as a building block to construct the whole randomized auction mechanism. Compared with deterministic auction mechanisms, the proposed randomized auction mechanism increases the diversity in contributing users for a given sensing job. We carry out both solid theoretical analysis and extensive numerical studies and show that our randomized auction mechanism achieves approximate truthfulness, individual rationality, and high computational efficiency. Auteurs: Juan Li;Yanmin Zhu;Yiqun Hua;Jiadi Yu; Apparue dans: IEEE Transactions on Mobile Computing Date publication: 10.-2017, volume: 16, issue:10, pages: 2764 - 2777 Editeur: IEEE Document complet vers site de l'éditeur
» Cryptanalysis of Controlled Bidirectional Quantum Secure Direct Communication Network Using Classical XOR Operation and Quantum Entanglement
 Résumé:The multi-user controlled bidirectional quantum secure direct communication network protocol based on classical EXCLUSIVE-OR operation and quantum entanglement is analyzed. It is shown that this protocol has the information leakage problem, that is, one half of the information the users transmit is leaked out unconsciously. Furthermore, it is also weak against the intercept-measure-resend attack and the Controlled-Not operation attack from an outside adversary, and the different initial state attack from the controller. Auteurs: Zhihao Liu;Hanwu Chen; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2202 - 2205 Editeur: IEEE Document complet vers site de l'éditeur
» Cumulation of High-Current Electron Beams: Theory and Experiment
 Résumé:High-power electron beam cumulation in a relativistic vacuum diode with a ring-type cathode is considered. The term “electron beam cumulation” here means electron beam self-focusing accompanied with multifold beam current density increase on the beam axis compared to the average current density in the cathode-anode gap. Space-charge repulsion of electrons emitted by the explosive-emission plasma on the inner edge of the cathode is shown to be the origin of this cumulation mechanism. Current density in the vicinity of beam axis is evaluated for different cathode inner diameter values both numerically and experimentally. Cathode with eccentric apertures of different diameters is studied experimentally. Auteurs: Sergei Anishchenko;Vladimir Baryshevsky;Nikolai Belous;Alexandra Gurinovich;Elizaveta Gurinovich;Evgeny Gurnevich;Pavel Molchanov; Apparue dans: IEEE Transactions on Plasma Science Date publication: 10.-2017, volume: 45, issue:10, pages: 2739 - 2743 Editeur: IEEE Document complet vers site de l'éditeur
» Cumulative Dual Foreground Differences for Illegally Parked Vehicles Detection
 Résumé:Illegally parked vehicles on the urban road may create a traffic flow problem as well as a potential traffic accident, such as crashing between parked and other vehicles. Thus, the intelligent traffic monitoring system should be able to prevent this situation by integrating an illegally parked vehicle detection module. However, implementing such a module becomes more challenging due to road environments, such as weather conditions, occlusion, and illumination changing. Hence, this work addresses a method to implement an illegally parked vehicle detection based on the cumulative dual foreground differences from the short- and long-term background models, temporal analysis, vehicle detector, and tracking. The extensive experiments were conducted using both iLIDS and our proposed datasets to evaluate the effectiveness of the proposed method by comparing with other methods. The results showed that the method is effective in detecting illegally parked vehicles and can be considered as part of the intelligent traffic monitoring system. Auteurs: Wahyono;Kang-Hyun Jo; Apparue dans: IEEE Transactions on Industrial Informatics Date publication: 10.-2017, volume: 13, issue:5, pages: 2464 - 2473 Editeur: IEEE Document complet vers site de l'éditeur
» Current Noise Cancellation for Bearing Fault Diagnosis Using Time Shifting
 Résumé:The stator current of a typical induction motor involves the supply fundamental and its harmonics existing before and after the presence of a bearing defect, and much of the information they contain is not related to the bearing defect. In this sense, they are basically noise to bearing fault diagnosis problem. This paper develops a current noise cancellation method using time shifting. Current residue is obtained by adding digital current signal to its own sample-delayed representation as an antinoise component. The amount of the sample delay is only dependent upon the supply frequency and the sampling rate. This amount is set to eliminate the supply fundamental and its odd multiple harmonics. After obtaining the current residue, through the spectral analysis of the envelope of the current residue, the characteristic fault frequencies for a defective bearing can be revealed. To show the superiority, the developed method is experimentally compared with three of the current-based methods in the literature. Experimental results for the defects in the outer raceway, the inner raceway, and the ball of a bearing verify the merits and effectiveness of the developed method. Auteurs: Fardin Dalvand;Satar Dalvand;Fatemeh Sharafi;Michael Pecht; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 8138 - 8147 Editeur: IEEE Document complet vers site de l'éditeur
» Current-Detection-Independent Dead-Time Compensation Method Based on Terminal Voltage A/D Conversion for PWM VSI
 Résumé:Dead-time insertion increases noise and torque pulsation in motors under open-loop constant V/f control, and it results in instability in motors under sensorless field-orientated control or direct torque control at low speed, degrading performance of motor drive systems. In order to overcome the drawback of dead-time insertion, a novel current-detection-independent dead-time compensation technique based on terminal voltage A/D conversion is proposed in this paper. Both current polarity and compensation time can be extracted from the sampled terminal voltage. Experiments on an induction motor rated at 210 V, 2.2 kW demonstrated the proposed technique can significantly improve the performance of the fixed compensation, online compensation, and even the feedback compensation method. The proposed scheme does not rely on current sensors, and thus can be applied to both open-loop and closed-loop motor drive systems. When combined with the fixed compensation method, the performance of the proposed technique is even comparable with the feedback compensation method within a large frequency range, making it very attractive for open-loop constant V/f drives where current sensors are not available. Auteurs: Gang Liu;Dafang Wang;Yi Jin;Miaoran Wang;Peng Zhang; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7689 - 7699 Editeur: IEEE Document complet vers site de l'éditeur
» Current-Feed Single-Switch Forward Resonant DC Transformer (DCX) With Secondary Diode-Clamping
 Résumé:A simple current-feed single-switch forward resonant converter with secondary diode-clamping is proposed for low-power high-density bus converter applications in this paper. The quasi-zero-voltage-switching turn-on and quasi-zero-current-switching (ZCS) turn-off for switch are both achieved. Due to the quasi-ZCS turn-off , the high voltage spike in traditional single forward converter with a reset winding is much reduced. A small diode connected to the output capacitor is utilized to clamp the voltage stress of the switches. The operating principle of the proposed converter is analyzed and a MHz 66 W 24 V-to-12 V prototype with all Si devices is built up. Experimental results show good soft-switching features, and the prototype achieves 95.3% peak efficiency with 270 W/in3 power density. Auteurs: Wei Qin;Xinke Wu;Junming Zhang; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 7790 - 7799 Editeur: IEEE Document complet vers site de l'éditeur
» CUTE Mote, A Customizable and Trustable End-Device for the Internet of Things
 Résumé:The ubiquitous connectivity of the low-end devices in the Internet of Things (IoT) brings new challenges over the traditional wireless sensor networks’ architectures. Such challenges require not only security and privacy-related features, but also solutions to handle the ever-growing amount of data transferred over the network. However, performing such tasks on resource constrained devices is not straightforward. The need for energy-efficient devices, while preserving their performance and security capabilities, requires new solutions at the architectural level of the wireless device. This paper proposes a heterogeneous architecture that targets low-end and resource constrained IoT devices, combining a hardcore microcontroller unit (MCU) and a reconfigurable computing unit (RCU) with an IEEE 802.15.4 radio transceiver. The MCU hosts an embedded operating system with an IoT-enabled network stack, and exploits the available field-programmable gate array technology to implement the RCU and to deploy customized sensing- and network-related accelerators, offloading heavy, and/or complex software tasks to dedicated hardware blocks. The customizable and trustable end-device mote was implemented using the proposed architecture and the achieved results demonstrates the benefits, both in terms of performance and energy, of accelerating network-related tasks in always-connected resource constrained IoT devices. Auteurs: Tiago Gomes;Filipe Salgado;Adriano Tavares;Jorge Cabral; Apparue dans: IEEE Sensors Journal Date publication: 10.-2017, volume: 17, issue:20, pages: 6816 - 6824 Editeur: IEEE Document complet vers site de l'éditeur
» CVaR-Constrained Optimal Bidding of Electric Vehicle Aggregators in Day-Ahead and Real-Time Markets
 Résumé:An electric vehicle aggregator (EVA) that manages geographically dispersed electric vehicles offers an opportunity for the demand side to participate in electricity markets. This paper proposes an optimization model to determine the day-ahead inflexible bidding and real-time flexible bidding under market uncertainties. Based on the relationship between market price and bid price, the proposed optimal bidding model of EVA aims to minimize the conditional expectation of electricity purchase cost in two markets considering price volatility. Moreover, the penalty cost of the deviation between the bidding quantities is included to avoid large power variation and arbitrage. The conditional expectation optimization model is formulated as an expectation minimization problem with the conditional value-at-risk constraints. Based on the price data in the PJM market, simulation results verify that our model is a decision-making tool in electricity markets, which can help market players comprehend the variants of bid price, expected cost and probability of successful bidding. Auteurs: Hongming Yang;Sanhua Zhang;Jing Qiu;Duo Qiu;Mingyong Lai;ZhaoYang Dong; Apparue dans: IEEE Transactions on Industrial Informatics Date publication: 10.-2017, volume: 13, issue:5, pages: 2555 - 2565 Editeur: IEEE Document complet vers site de l'éditeur
» Cybersecurity and Rural Electric Power Systems: Considering Competing Requirements for Implementing a Protection Plan
 Résumé:Cybersecurity is a topic of increasing importance and interest to small utility operators like rural electric associations. Cyberattacks are a threat to our society's functioning, and cybersecurity is an urgent need in areas that include national security, business operations, and regulatory compliance. Several fundamental concepts can guide an operator when implementing a cybersecurity plan. Operators must consider the competing requirements of confidentiality, integrity, availability (CIA), and cost. They must also consider the potential of impact levels for an incident. While implementing a cybersecurity plan, operators will constantly identify adversaries, threats, vulnerabilities, consequences, and risks. They will implement physical, technical, and administrative controls to protect networks and other assets, detect attacks, respond to those attacks, and recover from any damage. The process will be continuous as operators respond to the changing environment. Auteurs: Paul Kaster;Pankaj P.K. Sen; Apparue dans: IEEE Industry Applications Magazine Date publication: 10.-2017, volume: 23, issue:5, pages: 14 - 20 Editeur: IEEE Document complet vers site de l'éditeur
» Cybersecurity in Power Systems
 Résumé:Did you know that cyberattackers have already created outages in Ukraine, not once but twice? On 23 December 2015, cyberintruders at three electric distribution companies in Ukraine opened breakers, creating a power outage that affected 225,000 people. Power was restored in approximately 6 h, as field personnel manually closed the breakers. Auteurs: Michael F. Ahern; Apparue dans: IEEE Potentials Date publication: 10.-2017, volume: 36, issue:5, pages: 8 - 12 Editeur: IEEE Document complet vers site de l'éditeur
» Daily Clearness Index Profiles Cluster Analysis for Photovoltaic System
 Résumé:Due to various weather perturbation effects, the stochastic nature of real-life solar irradiance has been a major issue for solar photovoltaic (PV) system planning and performance evaluation. This paper aims to discover clearness index (CI) patterns and to construct centroids for the daily CI profiles. This will be useful in being able to provide a standardized methodology for PV system design and analysis. Four years of solar irradiance data collected from Johannesburg (26.21 S, 28.05 E), South Africa are used for the case study. The variation in CI could be significant in different seasons. In this paper, cluster analysis with Gaussian mixture models (GMM), K-Means with Euclidean distance (ED), K-Means with Manhattan distance, Fuzzy C-Means (FCM) with ED, and FCM with dynamic time warping (FCM DTW) are performed for the four seasons. A case study based on sizing a stand-alone solar PV and storage system with anaerobic digestion biogas power plants is used to examine the usefulness of the clustering results. It concludes that FCM DTW and GMM can determine the correct PV farm rated capacity with an acceptable energy storage capacity, with 36 and 46 rather than 1457 solar irradiance profiles, respectively. Auteurs: Chun Sing Lai;Youwei Jia;Malcolm D. McCulloch;Zhao Xu; Apparue dans: IEEE Transactions on Industrial Informatics Date publication: 10.-2017, volume: 13, issue:5, pages: 2322 - 2332 Editeur: IEEE Document complet vers site de l'éditeur
» Damping Dependence of Spin-Torque Effects in Thermally Assisted Magnetization Reversal
 Résumé:Thermal fluctuations of nanomagnets driven by spin-polarized currents are treated via the Landau–Lifshitz–Gilbert equation as generalized to include both the random thermal noise field and Slonczewski spin-transfer torque terms. The magnetization reversal time of such a nanomagnet is then evaluated for wide ranges of damping by using a method which generalizes the solution of the so-called Kramers turnover problem for mechanical Brownian particles, thereby bridging the very low damping and intermediate damping Kramers escape rates, to the analogous magnetic turnover problem. The reversal time is then evaluated for a nanomagnet with the free energy density given in the standard form of superimposed easy-plane and in-plane easy-axis anisotropies with the dc bias field along the easy axis. Auteurs: Y. P. Kalmykov;D. Byrne;W. T. Coffey;W. J. Dowling;S. V. Titov;J. E. Wegrowe; Apparue dans: IEEE Transactions on Magnetics Date publication: 10.-2017, volume: 53, issue:10, pages: 1 - 8 Editeur: IEEE Document complet vers site de l'éditeur
» Data Backup Optimization for Nonvolatile SRAM in Energy Harvesting Sensor Nodes
 Résumé:Nonvolatile static random access memory (nvSRAM) has been widely investigated as a promising on-chip memory architecture in energy harvesting sensor nodes, due to zero standby power, resilience to power failures, and fast read/write operations. However, conventional approaches back up all data from static random access memory into nonvolatile memory when power failures happen. It leads to significant energy overhead and peak inrush current, which has a negative impact on the system performance and circuit reliability. This paper proposes a holistic data backup optimization to mitigate these problems in nvSRAM, consisting of a partial backup algorithm and a run-time adaptive write policy. A statistic dead-block predictor is employed to achieve dead block identification with trivial hardware overhead. An adaptive policy is used to switch between write-back and write-through strategy to reduce the rollback induced by backup failures. Experimental results show that the proposed scheme improves the performance by 4.6% on average while the backup power consumption and the inrush current are reduced by 38.1% and 54% on average compared to the full backup scheme. What is more, the backup capacitor size for energy buffer can be reduced by 40% on average under the same performance constraint. Auteurs: Yongpan Liu;Jinshan Yue;Hehe Li;Qinghang Zhao;Mengying Zhao;Chun Jason Xue;Guangyu Sun;Meng-Fan Chang;Huazhong Yang; Apparue dans: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems Date publication: 10.-2017, volume: 36, issue:10, pages: 1660 - 1673 Editeur: IEEE Document complet vers site de l'éditeur
» Data-Based Predictive Optimization for Byproduct Gas System in Steel Industry
 Résumé:In light of significant complexity of the byproduct gas system in steel industry (which limits an ability to establish its physics-based model), this paper proposes a data-based predictive optimization (DPO) method to carry out real-time adjusting for the gas system. Two stages of the method, namely, the prediction modeling and real-time optimization, are involved. At the prediction stage, the states of the optimized objectives, the consumption of the outsourcing natural gas and oil, the power generation, and the tank levels, are forecasted based on a proposed mixed Gaussian kernel-based prediction intervals (PIs) construction model. The Jacobian matrix of this model is represented by a kernel matrix through derivation, which greatly facilitates the subsequent calculation. At the second stage, a rolling optimization based on a mathematical programming technique involving continuous and integer decision-making variables is developed via the PIs. To demonstrate the performance of the DPO method, the practical data coming from the energy center of a steel plant are employed. The results show that the proposed DPO method can supply the human operators with effective solution for secure and economically justified optimization of the gas system.Note to Practitioners—Given that the byproduct gas system in steel industry can hardly be described by a physics or mechanism-based model, its operation is widely realized by the experience-based manual measure at present, which exhibits a very low automation level. Since a large number of real-time energy data have been accumulated by the existing SCADA system implemented in most of steel plants, a novel data-driven real-time predictive optimization method is proposed in this study.The proposed method aims at the short term energy optimization, thus the sample interval of the real-time data acquired from the SCADA system is set as 1 minute. The application system can provide the r- lling optimized solution via real-time predicting the running circumstances of the gas system. Therefore, it is required for the plant in advance to implement the SCADA system for the energy data acquisition, and the sampling interval should be less than or equal to 1 minute. Furthermore, it is necessary for the sample data to complete the preliminary processing such as data imputation if needed since there are usually a large number of possible missing data points existed in the SCADA system of the production practice. Because such preliminary processing for the sample data belongs to a class of generic methods, this study avoids the redundant technical introduction. Auteurs: Jun Zhao;Chunyang Sheng;Wei Wang;Witold Pedrycz;Quanli Liu; Apparue dans: IEEE Transactions on Automation Science and Engineering Date publication: 10.-2017, volume: 14, issue:4, pages: 1761 - 1770 Editeur: IEEE Document complet vers site de l'éditeur
» Data-Driven Distributed Local Fault Detection for Large-Scale Processes Based on the GA-Regularized Canonical Correlation Analysis
 Résumé:Large-scale processes have become common, and fault detection for such processes is imperative. This work studies the data-driven distributed local fault detection problem for large-scale processes with interconnected subsystems and develops a genetic algorithm (GA)-regularized canonical correlation analysis (CCA)-based distributed local fault detection scheme. For each subsystem, the GA-regularized CCA is first performed with its all coupled systems, which aims to preserve the maximum correlation with the minimal communication cost. A CCA-based residual is then generated, and corresponding statistic is constructed to achieve optimal fault detection for the subsystem. The distributed fault detector performs local fault detection for each subsystem using its own measurements and the information provided by its coupled subsystems and therefore exhibits a superior monitoring performance. The regularized CCA-based distributed fault detection approach is tested on a numerical example and the Tennessee Eastman benchmark process. Monitoring results indicate the efficiency and feasibility of the proposed approach. Auteurs: Qingchao Jiang;Steven X. Ding;Yang Wang;Xuefeng Yan; Apparue dans: IEEE Transactions on Industrial Electronics Date publication: 10.-2017, volume: 64, issue:10, pages: 8148 - 8157 Editeur: IEEE Document complet vers site de l'éditeur
» DC and RF Performance of AlGaN/GaN/SiC MOSHEMTs With Deep Sub-Micron T-Gates and Atomic Layer Epitaxy MgCaO as Gate Dielectric
 Résumé:In this letter, we report on the dc and RF performance of AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors (MOSHEMTs) with various gate lengths ( ${L}_{\mathsf {G}}$ ) from 90 to 500 nm using atomic-layer-epitaxy single crystalline Mg0.25Ca0.75O as gate dielectric. The 90-nm T-gate MOSHEMT simultaneously demonstrates a ft/fmax of 113/160 GHz with high on/off ratio of $5\times 10^{8}$ . The on/off ratio increases to $2\times 10^{11}$ at ${L}_{\mathsf {G}}=350$ nm by reducing short channel effects. The gate leakage current is around 10−11 A/mm at off-state and 10−5 A/mm at on-state. A 160 nm ${L}_{\mathsf {G}}$ MOSHEMT also exhibits an output power density of 4.18 W/mm at ${f} = 35$ GHz and ${V}_{\mathsf {DS}}=20$ V. MgCaO demonstrates to be a promising dielectric for GaN MOS technology in serving as the surface passivation layer and reducing the gate leakage current while maintaining high RF performances for high-power applications. Auteurs: Hong Zhou;Xiabing Lou;Karynn Sutherlin;Jarren Summers;Sang Bok Kim;Kelson D. Chabak;Roy G. Gordon;Peide D. Ye; Apparue dans: IEEE Electron Device Letters Date publication: 10.-2017, volume: 38, issue:10, pages: 1409 - 1412 Editeur: IEEE Document complet vers site de l'éditeur
» DC-Link Current and Torque Ripple Optimized Self-Sensing Control of Interior Permanent-Magnet Synchronous Machines for Hybrid and Electrical Vehicles
 Résumé:To minimize the ripple on the dc-link current and torque due to carrier signal injections, conventional saliency based self-sensing control schemes using voltage and current carrier signals for interior permanent magnet synchronous machines (IPMSMs) are optimized in this paper. Carrier signal oriented coordinates are introduced to model the high-frequency behavior of IPMSMs and are used for the analysis and signal processing of proposed methods. Moreover, stability issues are discussed in this paper. Experimental results on a commercial high voltage inverter for application in hybrid and electrical vehicles confirm the applicability of the proposed methods. Auteurs: Lei Chen;Gunther Götting;Ingo Hahn; Apparue dans: IEEE Transactions on Industry Applications Date publication: 10.-2017, volume: 53, issue:5, pages: 4536 - 4546 Editeur: IEEE Document complet vers site de l'éditeur
» Deadline-Aware Opportunistic Network Coding for Multi-Relay-Aided Single-Source Single-Destination Network
 Résumé:An opportunistic network coding (NC) scheme is proposed for the multi-relay-aided single-source single-destination network with transmission deadline. With the help of matrix analysis, the lower bound of decoding failure probability of the proposed scheme is given. Simulation results show that: 1) the proposed scheme outperforms NC based on direct recoding scheme and the lower bound is tight when the source-to-relay channel erasure probability is relatively small and 2) given fixed network parameters, the optimal number of systematic packets delivered within deadline could be determined by using the derived bound for maximizing the throughput. Auteurs: Guojie Hu;Kui Xu;Youyun Xu; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2282 - 2285 Editeur: IEEE Document complet vers site de l'éditeur
» Decomposing Joint Distortion for Adaptive Steganography
 Résumé:Recent advances on adaptive steganography imply that the security of steganography can be improved by exploiting the mutual impact of modifications between adjacent cover elements, such as pixels of images, which is called a nonadditive distortion model. In this paper, we propose a framework for nonadditive distortion steganography by defining joint distortion on pixel blocks. To reduce the complexity for minimizing joint distortion, we design a coding method to decompose the joint distortion (abbreviated to DeJoin) into distortion on individual pixels; thus, the message can be efficiently embedded with syndrome-trellis codes. We prove that DeJoin can approach the lower bound of joint distortion. As an example, we define joint distortion according to the principle of synchronizing modification direction and then design steganographic algorithms with DeJoin. The experimental results show that the proposed method outperforms previous nonadditive distortion steganography when resisting the state-of-the-art steganalysis. Auteurs: Weiming Zhang;Zhuo Zhang;Lili Zhang;Hanyi Li;Nenghai Yu; Apparue dans: IEEE Transactions on Circuits and Systems for Video Technology Date publication: 10.-2017, volume: 27, issue:10, pages: 2274 - 2280 Editeur: IEEE Document complet vers site de l'éditeur
» Decoupled Uplink-Downlink User Association in Multi-Tier Full-Duplex Cellular Networks: A Two-Sided Matching Game
 Résumé:In multi-tier cellular networks, user performance in both the downlink (DL) and uplink (UL) transmissions depend on the transmit powers of the base stations (BSs) in different network tiers, users' distances, and non-uniform traffic loads of different BSs. In such a network, decoupled UL-DL user association (DUDe), which allows users to associate with different BSs for UL and DL transmissions, can be used to optimize network performance. Again, in-band full-duplex (FD) communication is considered as a promising technique to improve the spectral efficiency of future multi-tier fifth generation (5G) cellular networks. Nonetheless, due to UL-to-DL and DL-to-UL interferences arising due to FD communications, the performance gains of DUDe in FD multi-tier networks are inconspicuous. To this end, this paper develops a comprehensive framework to analyze the usefulness of DUDe in a full-duplex multi-tier cellular network. We first formulate a joint UL and DL user association problem (with the provisioning for decoupled association) that maximizes the sum-rate for UL and DL transmission of all users. Since the formulated problem is a mixed-integer non-linear programming (MINLP) problem, we invoke approximations and binary constraint relaxations to convert the problem into a Geometric Programming (GP) problem that is solved by using Karush-Kuhn-Tucker (KKT) optimality conditions. Given the centralized nature and complexity of the GP problem, we formulate a distributed two-sided iterative matching game and obtain a solution of the game. In this game, the users and BSs rank one another using preference metrics that are subject to the externalities (i.e., dynamic interference conditions). The solution of the game is guaranteed to converge and provides Pareto-optimal stable associations. Finally, we derive efficient light-weight versions of the iterative matching solution, i.e., non-iterative matching and sequential UL-DL matching algorithms. The performances of the solutions a- e evaluated in terms of aggregate UL and DL rates of all users, the number of unassociated users, and the number of coupled/decoupled associations. Simulation results demonstrate the efficacy of the proposed algorithms over the centralized GP solution as well as traditional coupled and decoupled user association schemes. Auteurs: Silvia Sekander;Hina Tabassum;Ekram Hossain; Apparue dans: IEEE Transactions on Mobile Computing Date publication: 10.-2017, volume: 16, issue:10, pages: 2778 - 2791 Editeur: IEEE Document complet vers site de l'éditeur
» Decoy-State Reference-Frame-Independent Measurement-Device-Independent Quantum Key Distribution With Biased Bases
 Résumé:Reference-frame-independent measurement-device-independent quantum key distribution (RFI-MDI-QKD) can eschew the alignment of reference frames in practical systems and defeat all potential detector side channel attacks. Here, we propose the decoy-state RFI-MDI-QKD protocol with biased bases. In this protocol, two legitimate parties Alice and Bob prepare signal states in $Z$, $X$, and $Y$ bases and decoy states in $X$ and $Y$ bases, which avoids the futility in $Z$ basis for decoy states and simplifies the operation of existing systems. Considering the security against coherent attacks with statistical fluctuations, we investigate the performance of the decoy-state RFI-MDI-QKD protocol with biased bases in the environment of unknown and slowly drifting reference frames and make comparisons with the original decoy-state RFI-MDI-QKD protocol under the same conditions. Simulation results show that the proposed protocol can increase the achievable secret key rate and transmission distance obviously compared with the original protocol, which is very promising in real-life QKD systems. Auteurs: Chun-Mei Zhang;Jian-Rong Zhu;Qin Wang; Apparue dans: Journal of Lightwave Technology Date publication: 10.-2017, volume: 35, issue:20, pages: 4574 - 4578 Editeur: IEEE Document complet vers site de l'éditeur
» Deep Conditional Random Field Approach to Transmembrane Topology Prediction and Application to GPCR Three-Dimensional Structure Modeling
 Résumé:Transmembrane proteins play important roles in cellular energy production, signal transmission, and metabolism. Many shallow machine learning methods have been applied to transmembrane topology prediction, but the performance was limited by the large size of membrane proteins and the complex biological evolution information behind the sequence. In this paper, we proposed a novel deep approach based on conditional random fields named as dCRF-TM for predicting the topology of transmembrane proteins. Conditional random fields take into account more complicated interrelation between residue labels in full-length sequence than HMM and SVM-based methods. Three widely-used datasets were employed in the benchmark. DCRF-TM had the accuracy 95 percent over helix location prediction and the accuracy 78 percent over helix number prediction. DCRF-TM demonstrated a more robust performance on large size proteins (>350 residues) against 11 state-of-the-art predictors. Further dCRF-TM was applied to ab initio modeling three-dimensional structures of seven-transmembrane receptors, also known as G protein-coupled receptors. The predictions on 24 solved G protein-coupled receptors and unsolved vasopressin V2 receptor illustrated that dCRF-TM helped abGPCR-I-TASSER to improve TM-score 34.3 percent rather than using the random transmembrane definition. Two out of five predicted models caught the experimental verified disulfide bonds in vasopressin V2 receptor. Auteurs: Hongjie Wu;Kun Wang;Liyao Lu;Yu Xue;Qiang Lyu;Min Jiang; Apparue dans: IEEE/ACM Transactions on Computational Biology and Bioinformatics Date publication: 10.-2017, volume: 14, issue:5, pages: 1106 - 1114 Editeur: IEEE Document complet vers site de l'éditeur
» Deep Fully Convolutional Network-Based Spatial Distribution Prediction for Hyperspectral Image Classification
 Résumé:Most of the existing spatial-spectral-based hyperspectral image classification (HSIC) methods mainly extract the spatial-spectral information by combining the pixels in a small neighborhood or aggregating the statistical and morphological characteristics. However, those strategies can only generate shallow appearance features with limited representative ability for classes with high interclass similarity and spatial diversity and therefore reduce the classification accuracy. To this end, we present a novel HSIC framework, named deep multiscale spatial-spectral feature extraction algorithm, which focuses on learning effective discriminant features for HSIC. First, the well pretrained deep fully convolutional network based on VGG-verydeep-16 is introduced to excavate the potential deep multiscale spatial structural information in the proposed hyperspectral imaging framework. Then, the spectral feature and the deep multiscale spatial feature are fused by adopting the weighted fusion method. Finally, the fusion feature is put into a generic classifier to obtain the pixelwise classification. Compared with the existing spectral-spatial-based classification techniques, the proposed method provides the state-of-the-art performance and is much more effective, especially for images with high nonlinear distribution and spatial diversity. Auteurs: Licheng Jiao;Miaomiao Liang;Huan Chen;Shuyuan Yang;Hongying Liu;Xianghai Cao; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5585 - 5599 Editeur: IEEE Document complet vers site de l'éditeur
» Deep Learning of Graphs with Ngram Convolutional Neural Networks
 Résumé:Convolutional Neural Network (CNN) has gained attractions in image analytics and speech recognition in recent years. However, employing CNN for classification of graphs remains to be challenging. This paper presents the Ngram graph-block based convolutional neural network model for classification of graphs. Our Ngram deep learning framework consists of three novel components. First, we introduce the concept of $n$ -gram block to transform each raw graph object into a sequence of $n$ -gram blocks connected through overlapping regions. Second, we introduce a diagonal convolution step to extract local patterns and connectivity features hidden in these $n$ -gram blocks by performing $n$ -gram normalization. Finally, we develop deeper global patterns based on the local patterns and the ways that they respond to overlapping regions by building a $n$ -gram deep learning model using convolutional neural network. We evaluate the effectiveness of our approach by comparing it with the existing state of art methods using five real graph repositories from bioinformatics and social networks domains. Our results show that the Ngram approach outperforms existing methods with high accuracy and comparable performance. Auteurs: Zhiling Luo;Ling Liu;Jianwei Yin;Ying Li;Zhaohui Wu; Apparue dans: IEEE Transactions on Knowledge and Data Engineering Date publication: 10.-2017, volume: 29, issue:10, pages: 2125 - 2139 Editeur: IEEE Document complet vers site de l'éditeur
» Deep TSK Fuzzy Classifier With Stacked Generalization and Triplely Concise Interpretability Guarantee for Large Data
 Résumé:Although Takagi–Sugeno–Kang (TSK) fuzzy classifier has been applied to a wide range of practical scenarios, how to enhance its classification accuracy and interpretability simultaneously is still a challenging task. In this paper, based on the powerful stacked generalization principle, a deep TSK fuzzy classifier (D-TSK-FC) is proposed to achieve the enhanced classification accuracy and triplely concise interpretability for fuzzy rules. D-TSK-FC consists of base-building units. Just like the existing popular deep learning, D-TSK-FC can be built in a layer-by-layer way. In terms of the stacked generalization principle, the training set plus random shifts obtained from random projections of prediction results of current base-building unit are presented as the input of the next base-building unit. The hidden layer in each base-building unit of D-TSK-FC is represented by triplely concise interpretable fuzzy rules in the sense of randomly selected features with the fixed five fuzzy partitions, random rule combinations, and the same input space kept in every base-building unit of D-TSK-FC. The output layer of each base-building unit can be learnt quickly by least learning machine (LLM). Besides, benefiting from LLM, D-TSK-FC's deep learning can be well scaled up for large datasets. Our extensive experimental results witness the power of the proposed deep TSK fuzzy classifier. Auteurs: Ta Zhou;Fu-Lai Chung;Shitong Wang; Apparue dans: IEEE Transactions on Fuzzy Systems Date publication: 10.-2017, volume: 25, issue:5, pages: 1207 - 1221 Editeur: IEEE Document complet vers site de l'éditeur
» DeepCloud: Ground-Based Cloud Image Categorization Using Deep Convolutional Features
 Résumé:Accurate ground-based cloud image categorization is a critical but challenging task that has not been well addressed. One of the essential issues that affect the performance is to extract the representative visual features. Nearly all of the existing methods rely on the hand-crafted descriptors (e.g., local binary patterns, CENsus TRsansform hISTogram, and scale-invariant feature transform). Their limited discriminative power indeed leads to the unsatisfactory performance. To alleviate this, we propose “DeepCloud” as a novel cloud image feature extraction approach by resorting to the deep convolutional visual features. In the recent years, the deep convolutional neural network (CNN) has achieved the promising results in lots of computer vision and image understanding fields. Nevertheless, it has not been applied to cloud image classification yet. Thus, we actually pay the first effort to fill this blank. Since cloud image classification can be attributed to a multi-instance learning problem, simply employing the convolutional features within CNN cannot achieve the promising result. To address this, Fisher vector encoding is applied to executing the spatial feature aggregation and high-dimensional feature mapping on the raw deep convolutional features. Moreover, the hierarchical convolutional layers are used simultaneously to capture the fine textural characteristics and high-level semantic information in the unified manner. To further leverage the performance, a cloud pattern mining and selection method are also proposed. It targets at finding the discriminative local patterns to better distinguish the different kinds of clouds. The experiments on a challenging ground-based cloud image data set demonstrate the superiority of the proposition over the state-of-the-art methods. Auteurs: Liang Ye;Zhiguo Cao;Yang Xiao; Apparue dans: IEEE Transactions on Geoscience and Remote Sensing Date publication: 10.-2017, volume: 55, issue:10, pages: 5729 - 5740 Editeur: IEEE Document complet vers site de l'éditeur
» Degradation Effects on Energy Absorption Capability and Time to Failure of Low Voltage Metal Oxide Varistors
 Résumé:Reliability of a surge protection device depends on the health of its protecting elements. Metal oxide Varistors (MOVs) are widely used in electric appliances and power distribution systems. They are known to degrade over time when they experience high-surges and long-duration transients. In this paper, more than 120 MOVs are subjected to nominal 8/20 μs unipolar and bipolar surges of 40 kA in different groups, up to different levels of degradations. Then, they are subjected to energy absorption capability (EAC) tests with ac currents, in a UL-certified lab. Their EAC, peak currents, and time to failures (TtFs) are measured and analyzed. Results show that although degradation due to surges might decrease EAC and TtF of the MOVs in a given current, the average EAC and TtF of degraded MOVs are increased for a certain applied over-voltage. This paper explains the reasons and proposes a model for a degraded MOV that shows a realistic behavior in a transient overvoltage (TOV) condition. Auteurs: Dawood Talebi Khanmiri;Roy Ball;Brad Lehman; Apparue dans: IEEE Transactions on Power Delivery Date publication: 10.-2017, volume: 32, issue:5, pages: 2272 - 2280 Editeur: IEEE Document complet vers site de l'éditeur
» Delay Properties of Energy Efficient Ethernet Networks
 Résumé:Networking operational costs and environmental concerns have lately driven the quest for energy efficient equipment. In wired networks, energy efficient Ethernet (EEE) interfaces can greatly reduce power demands when compared with regular Ethernet interfaces. Their power saving capabilities have been studied and modeled in many research articles in the last few years, together with their effects on traffic delay. However, to this date, all articles have considered them in isolation instead of as part of a network of EEE interfaces. In this letter, we develop a model for the traffic delay on a network of EEE interfaces. We prove that, whatever the network topology, the per interface delay increment due to the power savings capabilities is bounded and, in most scenarios, negligible. This confirms that EEE interfaces can be used in all but the most delay constrained scenarios to save considerable amounts of power. Auteurs: Miguel Rodríguez-Pérez;Sergio Herrería-Alonso;Manuel Fernández-Veiga;Cándido López-García; Apparue dans: IEEE Communications Letters Date publication: 10.-2017, volume: 21, issue:10, pages: 2194 - 2197 Editeur: IEEE Document complet vers site de l'éditeur
» Delay Robustness of an $\mathcal {L}_1$ Adaptive Controller for a Class of Systems With Unknown Matched Nonlinearities
 Résumé:This paper studies the delay robustness of an $\mathcal {L}_1$ adaptive controller designed for systems with unknown matched nonlinearities and unknown input-gain matrices. The analysis establishes rigorously the existence of a positive lower bound for the closed-loop system's time-delay margin (TDM), provided that a filter bandwidth and an adaptive gain are chosen sufficiently large. In this case, if the input delay is below a critical value, then the state and control input of the control system follow those of a nonadaptive, robust reference system closely. The analysis also suggests a way to estimate this lower bound for the delay robustness using Padé approximants. Results from forward simulation are consistent with the Padé estimate and with an explicit upper bound on the TDM which decays to 0 as the filter bandwidth grows without bound. Auteurs: Kim-Doang Nguyen;Yang Li;Harry Dankowicz; Apparue dans: IEEE Transactions on Automatic Control Date publication: 10.-2017, volume: 62, issue:10, pages: 5485 - 5491 Editeur: IEEE Document complet vers site de l'éditeur
» Delivering Real-Time Information Services on Public Transit: A Framework
 Résumé:Public transit is described by a wide range of data, which include sensor data, open data, and social network data. Data come in large real-time streams, and are heterogeneous. How to integrate such data in real time? We propose MOBility ANAlyzer (MOBANA), a distributed stream-based framework. MOBANA deals with the integration of heterogeneous information, processing efficiency, and redundancy reduction. As far as integration is concerned, MOBANA integrates data at different layers, and converts them into exchangeable data formats. Specifically, to integrate feed information, MOBANA uses an improved incremental text classifier, based on Kullback Leibler distance. As far as efficiency is concerned, MOBANA is implemented by distributed stream processing engine and distributed messaging system, which enable scalable, efficient, and reliable real-time processing. Specifically, within the transport domain, MOBANA identifies the real-time position of vehicles by an as-needed adjustment of planned position against the real-time position, thus dropping network load. As far as redundancy is concerned, MOBANA filters tweets through a three-fold similarity analysis, which encompasses geo-location, text, and image. In addition, MOBANA is a complete framework, which has been tested as a pilot with real data in the city of Pavia, Italy. Auteurs: Tianyi Ma;Gianmario Motta;Kaixu Liu; Apparue dans: IEEE Transactions on Intelligent Transportation Systems Date publication: 10.-2017, volume: 18, issue:10, pages: 2642 - 2656 Editeur: IEEE Document complet vers site de l'éditeur
» DEM Retrieval From Airborne LiDAR Point Clouds in Mountain Areas via Deep Neural Networks
 Résumé:Airborne light detection and ranging (LiDAR) remote sensing enables accurate estimation and monitoring of terrain and vegetation, and digital surface model (DSM) and digital elevation model (DEM) are vital analytical tools to achieve this estimation and monitoring. Among them, DSM can be directly acquired from airborne LiDAR point clouds; nevertheless, for the production of DEM, point clouds representing a surface of ground objects should be accurately filtered out at first. In some mountain forest areas, due to the limited penetration of airborne LiDAR, ground points sustain a serious lack, which results in the difficulty in producing accurate DEMs. To reduce the intricacy and subjectivity caused by the manual supplement to ground points, this letter proposes a new DEM retrieval method from airborne LiDAR point clouds in mountain areas based on deep neural networks (DNNs). With a DNN model trained by accurate DEMs and DSMs, DEM retrieval becomes much easier by inputting their DSM into this model for prediction. Experiments on Fujian and Hainan mountain data sets demonstrate the effectiveness of this supervised method. Auteurs: Yimin Luo;Hongchao Ma;Liguo Zhou; Apparue dans: IEEE Geoscience and Remote Sensing Letters Date publication: 10.-2017, volume: 14, issue:10, pages: 1770 - 1774 Editeur: IEEE Document complet vers site de l'éditeur
» Demonstration of a Novel Technique for Non-Intrusive In-Band OSNR Derivation Using Flexible Rate Optical Transponders Over a Live 727 km Flexible Grid Optical Link
 Résumé:In high speed optical transmission networks, OSNR is the key optical performance parameter. We propose a novel technique for non-intrusive in-band OSNR derivation based on real-time pre-FEC bit error rate (BER) measurement from optical transponders, which exploits pre-measured and calibrated pre-FEC BER versus OSNR curves and multiple modulation formats to ensure accurate OSNR derivation over a wide range. We report a successful field trial of this novel in-band OSNR technique, in which we have demonstrated and verified the accurate OSNR derivation over both a 359 km field trial link and a live 727 km flexible grid optical link using 64 GBaud flexible rate optical transponders with modulation formats 100G DP-QPSK, 200G DP-16QAM, and 200G DP–QPSK. Compared with standard signal “on” and “off” measurement, an OSNR accuracy within ±1 dB was achieved for all three modulation formats. We also investigated the impact of fiber nonlinearity at different signal powers on the accuracy of this technique. It is shown that this novel technique provides reliable and accurate OSNR derivation for the optical signals operating in normal power regime making it suitable for practical network applications. Auteurs: Yu Rong Zhou;Kevin Smith;John Weatherhead;Paul Weir;Andrew Lord;Jingxin Chen;Weiwei Pan;Daniel Tanasoiu;Shipeng Wu; Apparue dans: Journal of Lightwave Technology Date publication: 10.-2017, volume: 35, issue:20, pages: 4399 - 4405 Editeur: IEEE Document complet vers site de l'éditeur
» DENA: A Configurable Microarchitecture and Design Flow for Biomedical DNA-Based Logic Design
 Résumé:DNA is known as the building block for storing the life codes and transferring the genetic features through the generations. However, it is found that DNA strands can be used for a new type of computation that opens fascinating horizons in computational medicine. Significant contributions are addressed on design of DNA-based logic gates for medical and computational applications but there are serious challenges for designing the medium and large-scale DNA circuits. In this paper, a new microarchitecture and corresponding design flow is proposed to facilitate the design of multistage large-scale DNA logic systems. Feasibility and efficiency of the proposed microarchitecture are evaluated by implementing a full adder and, then, its cascadability is determined by implementing a multistage 8-bit adder. Simulation results show the highlight features of the proposed design style and microarchitecture in terms of the scalability, implementation cost, and signal integrity of the DNA-based logic system compared to the traditional approaches. Auteurs: Zohre Beiki;Ali Jahanian; Apparue dans: IEEE Transactions on Biomedical Circuits and Systems Date publication: 10.-2017, volume: 11, issue:5, pages: 1077 - 1086 Editeur: IEEE Document complet vers site de l'éditeur
» Depth Estimation Using an Infrared Dot Projector and an Infrared Color Stereo Camera
 Résumé:This paper proposes a method of estimating depth from two kinds of stereo images: color stereo images and infrared stereo images. An infrared dot pattern is projected on a scene by a projector so that infrared cameras can capture the scene textured by the dots and the depth can be estimated even where the surface is not textured. The cost volumes are calculated for the infrared and color stereo images for each frame and are extended in the time direction to define a spatiotemporal cost volume (st-cost volume). We also extend the cost volume filter in the time direction by modifying the cross-based local multipoint filter (CLMF) and applying it to the st-cost volumes in order to restrain flicker on the time-varying depth maps. To get a reliable cost volume, the infrared and color st-cost volumes are integrated into a single cost volume by selecting the cost of either the infrared or the color st-cost volumes according to the size of the adaptive kernel used for the CLMF. Then, a graphcut is executed on the cost volume in order to estimate the disparity robustly even when the baselines of the stereo cameras are set wide enough to ensure spatially high resolution in the depth direction and the shapes of blocks are deformed by the affine transformation. A 2D graphcut is executed on each scan line to reduce the processing time and memory consumption. We experimented with the proposed method using infrared color stereo data sets of scenes in the real world and evaluated its effectiveness by comparing it with other recent stereo matching methods and depth cameras. Auteurs: Kensuke Hisatomi;Masanori Kano;Kensuke Ikeya;Miwa Katayama;Tomoyuki Mishina;Yuichi Iwadate;Kiyoharu Aizawa; Apparue dans: IEEE Transactions on Circuits and Systems for Video Technology Date publication: 10.-2017, volume: 27, issue:10, pages: 2086 - 2097 Editeur: IEEE Document complet vers site de l'éditeur

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2012:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre
2011:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre
2010:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre
2009:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre