#### Electrical and Electronics Engineering publications abstract of: 10-2017 sorted by title, page: 13

» On Multiple AER Handshaking Channels Over High-Speed Bit-Serial Bidirectional LVDS Links With Flow-Control and Clock-Correction on Commercial FPGAs for Scalable Neuromorphic Systems
 Abstract:Address event representation (AER) is a widely employed asynchronous technique for interchanging “neural spikes” between different hardware elements in neuromorphic systems. Each neuron or cell in a chip or a system is assigned an address (or ID), which is typically communicated through a high-speed digital bus, thus time-multiplexing a high number of neural connections. Conventional AER links use parallel physical wires together with a pair of handshaking signals (request and acknowledge). In this paper, we present a fully serial implementation using bidirectional SATA connectors with a pair of low-voltage differential signaling (LVDS) wires for each direction. The proposed implementation can multiplex a number of conventional parallel AER links for each physical LVDS connection. It uses flow control, clock correction, and byte alignment techniques to transmit 32-bit address events reliably over multiplexed serial connections. The setup has been tested using commercial Spartan6 FPGAs attaining a maximum event transmission speed of 75 Meps (Mega events per second) for 32-bit events at a line rate of 3.0 Gbps. Full HDL codes (vhdl/verilog) and example demonstration codes for the SpiNNaker platform will be made available. Autors: Amirreza Yousefzadeh;Mirosław Jabłoński;Taras Iakymchuk;Alejandro Linares-Barranco;Alfredo Rosado;Luis A. Plana;Steve Temple;Teresa Serrano-Gotarredona;Steve B. Furber;Bernabé Linares-Barranco; Appeared in: IEEE Transactions on Biomedical Circuits and Systems Publication date: Oct 2017, volume: 11, issue:5, pages: 1133 - 1147 Publisher: IEEE
» On Network Footprint of Traffic Inspection and Filtering at Global Scrubbing Centers
 Abstract:Traffic diversion through powerful cloud-based scrubbing centers provides a solution for protecting against various DDoS attacks. In one respect, such a solution enables sanitizing attack traffic close to its source and saves precious resources for the network service provider. Contrarily, the diversion of the inspected traffic toward the scrubbing centers may increase its footprint in the network. The location of the scrubbing centers greatly affects the network resource utilization and, therefore, should be carefully considered in the design of the security service. In this paper, we investigate four deployment strategies and compare their performance on a network of Points-of-Presence and on several router level topologies obtained from the RocketFuel project. The deployment quality was measured using the following criteria: the footprint of the inspected traffic, the redistribution of load on the links, and the increase in communication latency. Our results show that the deployment strategy that is considered to perform well for locating network monitors by maximizing flow coverage results in the worst footprint when traffic diversion is employed. Overall, we show that the deployment strategy that is tailored for traffic filtering is also suitable for traffic monitoring, but not the other way around. Autors: Polina Zilberman;Rami Puzis;Yuval Elovici; Appeared in: IEEE Transactions on Dependable and Secure Computing Publication date: Oct 2017, volume: 14, issue:5, pages: 521 - 534 Publisher: IEEE
» On Secondary Control Approaches for Voltage Regulation in DC Microgrids
 Abstract:Centralized or decentralized secondary controller is commonly employed to regulate the voltage drop raised by the primary controller. However, in the case of high capacity microgrids (MGs) and long feeders with much voltage drop on the line resistances, the conventional methods may not guarantee the voltage regulation on the load busses within a suitable range. Therefore, in addition to compensate the voltage drop of the primary controller, it is necessary to regulate the voltage of critical loads. In this paper, a new voltage regulation strategy is proposed to regulate the voltage of MG by employing the average voltage of identified critical busses, which are determined by the proposed modal analysis. Numerical steady-state analysis and preliminary simulation results validate effectiveness of the proposed scheme. Furthermore, experimental results are performed to demonstrate the viability of the proposed approach. Autors: Saeed Peyghami;Hossein Mokhtari;Pooya Davari;Poh Chiang Loh;Frede Blaabjerg; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4855 - 4862 Publisher: IEEE
» On Synchronous and Asynchronous Discrete Time Heterogeneous Cyclic Pursuit
 Abstract:This paper considers synchronous and asynchronous heterogeneous cyclic pursuit in discrete time and obtains results on the consensus of both. It is shown that agents in synchronous heterogeneous cyclic pursuit system can achieve consensus with at most one negative gain, subject to a lower limit, which expands the reachable set although the asynchronous case may diverge when one of the agents has a negative gain. However, when all the gains are positive, positional consensus is achieved even in the asynchronous mode. The theoretical results are illustrated through simulations. Autors: Dwaipayan Mukherjee;Debasish Ghose; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5248 - 5253 Publisher: IEEE
» On the Complexity of Optimal Power Allocation in a Multi-Tone Multiuser Communication System
 Abstract:Consider a multi-tone multi-user communication system with interfering users and available tones. An effective approach to mitigate interference is through power control at transmitters. In this paper, we consider optimal power allocation to maximize a system utility function, and show that for the two tone cases () with min-rate, harmonic mean, and geometric mean utility functions, the corresponding optimal power allocation problem is NP-hard. This result fills an important gap in the existing literature, which settled the complexity status of different cases involving various utility functions and values of . Our proof is through a reduction from the partitioning problem for the min-rate utility function, and from the independent set problem for the harmonic mean and geometric mean utility functions. Autors: Marco Locatelli;Zhi-Quan Luo; Appeared in: IEEE Transactions on Information Theory Publication date: Oct 2017, volume: 63, issue:10, pages: 6622 - 6627 Publisher: IEEE
» On the Consensus of Homogeneous Multiagent Systems With Positivity Constraints
 Abstract:This paper investigates the consensus problem for multiagent systems, under the assumptions that the agents are homogeneous and described by a single-input positive state-space model, the mutual interactions are cooperative, and the static state-feedback law that each agent adopts to achieve consensus preserves the positivity of the overall system. Necessary conditions for the problem solvability, which allow us to address only the special case when the state matrix is irreducible, are provided. Under the irreducibility assumption, equivalent sets of sufficient conditions are derived. Special conditions either on the system description or on the Laplacian of the communication graph allow us to obtain necessary and sufficient conditions for the problem solvability. Finally, by exploiting some results about robust stability either of positive systems or of polynomials, further sufficient conditions for the problem solvability are derived. Numerical examples illustrate the proposed results. Autors: Maria Elena Valcher;Irene Zorzan; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5096 - 5110 Publisher: IEEE
» On the Design of Secure Non-Orthogonal Multiple Access Systems
 Abstract:This paper proposes a new design of non-orthogonal multiple access (NOMA) under secrecy considerations. We focus on a NOMA system, where a transmitter sends confidential messages to multiple users in the presence of an external eavesdropper. The optimal designs of decoding order, transmission rates, and power allocated to each user are investigated. Considering the practical passive eavesdropping scenario where the instantaneous channel state of the eavesdropper is unknown, we adopt the secrecy outage probability as the secrecy metric. We first consider the problem of minimizing the transmit power subject to the secrecy outage and quality of service constraints, and derive the closed-form solution to this problem. We then explore the problem of maximizing the minimum confidential information rate among users subject to the secrecy outage and transmit power constraints, and provide an iterative algorithm to solve this problem. We find that the secrecy outage constraint in the studied problems does not change the optimal decoding order for NOMA, and one should increase the power allocated to the user whose channel is relatively bad when the secrecy constraint becomes more stringent. Finally, we show the advantage of NOMA over orthogonal multiple access in the studied problems both analytically and numerically. Autors: Biao He;An Liu;Nan Yang;Vincent K. N. Lau; Appeared in: IEEE Journal on Selected Areas in Communications Publication date: Oct 2017, volume: 35, issue:10, pages: 2196 - 2206 Publisher: IEEE
» On the Estimation of Ground and Volume Polarimetric Covariances in Forest Scenarios With SAR Tomography
 Abstract:A two-layer model composed by ground and volume contributions has been proven suitable to describe the 3-D backscattering signatures of forest scenarios in a number of experiments. Under this hypothesis, the purpose of this letter is to investigate how synthetic aperture radar tomography (TomoSAR) can be used to estimate ground and volume polarimetric covariances and with which performance. An algorithm which is able to overcome the intrinsic ambiguity in the estimation problem is proposed, and it is shown to be a reliable alternative to the poorly performing full-rank Capon beamformer for estimating the ground polarimetric covariances. This performance improvement can be achieved, for instance, if an a priori knowledge of the ground topography (or an accurate estimate of it) is available. This analysis is carried out by processing an L-band TomoSAR stack acquired by the DLR’s E-SAR sensor over the temperate forest site of Traunstein. Autors: Matteo Pardini;Konstantinos Papathanassiou; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Oct 2017, volume: 14, issue:10, pages: 1860 - 1864 Publisher: IEEE
» On the Evaluation of the 4-D Reaction Integral for the Scalar Potential in Galerkin’s Method of Moments
 Abstract:Despite the great progress made in the evaluation of the 4-D reaction integrals arising in the method of moments applied to the surface integral equation formulations, there are still some aspects that deserve to be explored further. The focus in this paper lies in the evaluation of the 4-D reaction integral for the scalar potential. We demonstrate that, unless this integral is computed to machine precision in the whole impedance matrix, it is imperative to maintain the trianglewise balance in the evaluation of the scalar potential part. A small imbalance, even at very small error, results in a loss of degrees of freedom (DOFs) for the charge distribution, violating the null-space property of the divergence operator and yielding potentially spurious solutions. The effect, although present, may go unnoticed at the conventional frequency regimes, where the usual mesh sizes can be applied. However, it becomes more pronounced as we approach the quasi-static limit, eventually rendering spurious solutions at the frequencies higher than the classical low-frequency breakdown would. Autors: Diego Martínez Solís;Fernando Obelleiro Basteiro;Jose Manuel Taboada; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5356 - 5364 Publisher: IEEE
» On the Fundamental Limits of Random Non-Orthogonal Multiple Access in Cellular Massive IoT
 Abstract:Machine-to-machine (M2M) constitutes the communication paradigm at the basis of Internet of Things vision. M2M solutions allow billions of multi-role devices to communicate with each other or with the underlying data transport infrastructure without, or with minimal, human intervention. Current solutions for wireless transmissions originally designed for human-based applications thus require a substantial shift to cope with the capacity issues in managing a huge amount of M2M devices. In this paper, we consider the multiple access techniques as promising solutions to support a large number of devices in cellular systems with limited radio resources. We focus on non-orthogonal multiple access (NOMA) where, with the aim to increase the channel efficiency, the devices share the same radio resources for their data transmission. This has been shown to provide optimal throughput from an information theoretic point of view. We consider a realistic system model and characterize the system performance in terms of throughput and energy efficiency in an NOMA scenario with a random packet arrival model, where we also derive the stability condition for the system to guarantee the performance. Autors: Mahyar Shirvanimoghaddam;Massimo Condoluci;Mischa Dohler;Sarah J. Johnson; Appeared in: IEEE Journal on Selected Areas in Communications Publication date: Oct 2017, volume: 35, issue:10, pages: 2238 - 2252 Publisher: IEEE
» On the Generation of Nondiffracting Beams in Extremely Subwavelength Applications
 Abstract:In this paper, extremely subwavelength evanescent Bessel beam launchers are designed, simulated, and experimentally tested to generate nondiffracting beams. The launching apertures consist of several concentric coils strategically positioned to spatially filter the fields of a single actively fed radiating coil. The geometrical properties of each coil element of the aperture were obtained through a procedure based on the orthogonal matching pursuit algorithm in order to maximize the quality of the launched beam while minimizing manufacturing complexity. Two apertures with outer diameters of 64 and 48 mm were fabricated and the generated field distributions were measured at the operating frequencies of 13.66 and 13.86 MHz, respectively. Desired and measured field distributions exhibited correlations above 0.9 even as the distance from the aperture was increased, demonstrating the ability of the apertures to approximate the field distribution and harmonic content of a Bessel beam. This paper furthers the study and practical implementation of Bessel beams and other types of beams in extremely subwavelength applications such as focusing, wireless power transfer, magnetic stimulation, and microwave ablation. Autors: Erik Saturnino Gámez Rodríguez;Manjunath Machnoor;Gianluca Lazzi; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5228 - 5237 Publisher: IEEE
» On the Latent Variable Interpretation in Sum-Product Networks
 Abstract:One of the central themes in Sum-Product networks (SPNs) is the interpretation of sum nodes as marginalized latent variables (LVs). This interpretation yields an increased syntactic or semantic structure, allows the application of the EM algorithm and to efficiently perform MPE inference. In literature, the LV interpretation was justified by explicitly introducing the indicator variables corresponding to the LVs’ states. However, as pointed out in this paper, this approach is in conflict with the completeness condition in SPNs and does not fully specify the probabilistic model. We propose a remedy for this problem by modifying the original approach for introducing the LVs, which we call SPN augmentation. We discuss conditional independencies in augmented SPNs, formally establish the probabilistic interpretation of the sum-weights and give an interpretation of augmented SPNs as Bayesian networks. Based on these results, we find a sound derivation of the EM algorithm for SPNs. Furthermore, the Viterbi-style algorithm for MPE proposed in literature was never proven to be correct. We show that this is indeed a correct algorithm, when applied to selective SPNs, and in particular when applied to augmented SPNs. Our theoretical results are confirmed in experiments on synthetic data and 103 real-world datasets. Autors: Robert Peharz;Robert Gens;Franz Pernkopf;Pedro Domingos; Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence Publication date: Oct 2017, volume: 39, issue:10, pages: 2030 - 2044 Publisher: IEEE
» On the m-CAP Performance with Different Pulse Shaping Filters Parameters for Visible Light Communications
 Abstract:In pulse shaping filters, parameters such as the roll-off factor and the symbol span, which determine the overall performance, are of great importance when implementing a real-time system due to limited hardware resources. In this paper, we experimentally investigate a multiband carrier-less amplitude and phase (m-CAP) visible light communications (VLC) system employing such filters and assess the link performance for a range of filter lengths and show the relationship between the system data rate (or spectral efficiency) and computational complexity. We show that lower order m-CAP can offer the same system performance as higher order systems while offering much lower computational complexity. By optimizing the filter parameters and the order m of an m-CAP VLC link, we achieve the largest improvement in the data rate and bandwidth efficiency of 9.69% and 40.43%, respectively, when compared with 2- and 8-CAP. We also show that the m-CAP VLC link with can be designed with the same filter parameters to demonstrate a link with both the highest data rate and spectral efficiency simultaneously in contrast to lower order systems. Autors: Petr Chvojka;Khald Werfli;Stanislav Zvanovec;Paul Anthony Haigh;Vaclav Hubata Vacek;Petr Dvorak;Petr Pesek;Zabih Ghassemlooy; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 12 Publisher: IEEE
» On the Oblivious Transfer Capacity of Generalized Erasure Channels Against Malicious Adversaries: The Case of Low Erasure Probability
 Abstract:Noisy channels are a powerful resource for cryptography as they can be used to obtain information-theoretic secure key agreement, commitment, and oblivious transfer protocols, among others. Oblivious transfer (OT) is a fundamental primitive, since it is complete for secure multi-party computation, and the OT capacity characterizes how efficiently a channel can be used for obtaining string oblivious transfer. Ahlswede and Csiszár (ISIT’07) presented upper and lower bounds on the OT capacity of generalized erasure channels (GECs) against passive adversaries. In the case of GEC with erasure probability at least 1/2, the upper and lower bounds match and, therefore, the OT capacity was determined. It was later proved by Pinto et al. [IEEE Trans. Inf. Theory 57(8)] that the OT capacity is identical for passive and malicious adversaries. In the case of GEC with erasure probability smaller than 1/2, the known lower bound against passive adversaries that was established by Ahlswede and Csiszár does not match their upper bound and it was unknown whether this OT rate could be achieved against malicious adversaries as well. In this paper, we show that there is a protocol against malicious adversaries achieving the same OT rate that was obtained against passive adversaries. We obtain our results by a new combination of interactive hashing and typicality tests that are suitable for dealing with the case of low erasure probability (). Autors: Rafael Dowsley;Anderson C. A. Nascimento; Appeared in: IEEE Transactions on Information Theory Publication date: Oct 2017, volume: 63, issue:10, pages: 6819 - 6826 Publisher: IEEE
» On the Performance of Visible Light Communication Systems With Non-Orthogonal Multiple Access
 Abstract:Visible light communication (VLC) has been proposed as a promising and efficient solution to indoor ubiquitous broadband connectivity. In this paper, non-orthogonal multiple access, which has been recently introduced as an effective scheme for fifth generation (5G) wireless networks, is considered in the context of VLC systems under different channel uncertainty models. To this end, we first derive a novel closed-form expression for the bit-error-rate (BER) under perfect channel state information (CSI). Capitalizing on this, we then quantify the effect of noisy and outdated CSI by deriving a simple and accurate approximation for the former and a tight upper bound for the latter. The offered results are corroborated by respective results from extensive Monte Carlo simulations and assist in developing useful insights on the effect of imperfect CSI knowledge on the overall system performance. Furthermore, it was shown that while noisy CSI leads to slight degradation in the BER performance, outdated CSI can cause considerable performance degradation, if the order of the users’ channel gains change due to the involved mobility. Autors: Hanaa Marshoud;Paschalis C. Sofotasios;Sami Muhaidat;George K. Karagiannidis;Bayan S. Sharif; Appeared in: IEEE Transactions on Wireless Communications Publication date: Oct 2017, volume: 16, issue:10, pages: 6350 - 6364 Publisher: IEEE
» On the Practical Design of a High Power Density SiC Single-Phase Uninterrupted Power Supply System
 Abstract:This paper proposes a high power density SiC single-phase system potential for uninterrupted power supply applications. To get the high power density, the semiconductors, packaging, circuit topology, and thermal design are synthetically considered. To increase the switching frequency and reduce the size of the passive components, the SiC MOSFETs and diodes are chosen; to minimize the parasitic inductances and eliminate the snubbers, the SiC bare dies are packaged as the half-bridge (HB) modules; to remove the bulky dc-link capacitors, the full-bridge inverter and the active power filter are designed, and they are structured by using the fabricated SiC HB modules; and finally to dissipate the heat from such a compact enclosure in the cost-efficient way, the heat sink of the modules and the forced air cool system are well designed, and the thermal 3-D finite-element analysis model is built to survey the best cooling configuration. A 2-kVA prototype is built and tested, and the power density of the system is up to 58 W/in3 and the maximal efficiency is up to 98.3%. Autors: Cai Chen;Yu Chen;Yifan Tan;Jianming Fang;Fang Luo;Yong Kang; Appeared in: IEEE Transactions on Industrial Informatics Publication date: Oct 2017, volume: 13, issue:5, pages: 2704 - 2716 Publisher: IEEE
» On the Solution Set of the Admissible Bounded Control Problem via Orthogonal Polynomials
 Abstract:The complete set of solutions to the admissible bounded control problem of the Brunovsky control system of dimension for via orthogonal polynomials on and their second kind polynomials is obtained. For given an initial position and a time greater than the optimal time , we prove that there are only two bang-bang controls with switchings that steer the state trajectory to the origin exactly at time . Autors: Abdon E. Choque-Rivero; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5213 - 5219 Publisher: IEEE
» On the Stability Margin of Networked Dynamical Systems
 Abstract:This paper is concerned with the stability (gain and phase) margin of networked dynamical systems, e.g., vehicles in formation, each of which has access to the state of its neighbors and subsequently uses a state feedback gain for a certain global objective such as attitude synchronization. Here, the network topology is directed and described by a generalized Laplacian matrix . An individual dynamical system can adopt its own state feedback control law such as a linear-quadratic-regulator controller for an ample stability margin, but it may lose the stability margin to a great extent when the same control strategy utilizing relative state information is used after being interconnected with other dynamical systems. This paper reveals and elaborates upon the following four facts: First, the stability margin after interconnection is quantified via the minimum singular value of a frequency-dependent matrix made up of and ; Second, the stability margin of a networked dynamical system having a pole at the origin is at most the inverse of the zero-eigenvalue sensitivity of ; Third, there exists an upper bound of the stability margin that has a computational merit, and asymptotically converges to the exact margin with respect to network size, probability of link existence, and control gain in a random network setting; and finally, can be designed to maximize the stability margin. Numerical examples are provided to demonstrate the elaboration. Autors: Yoonsoo Kim; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5451 - 5456 Publisher: IEEE
» On the Sum-Rate Capacity of Poisson MISO Multiple Access Channels
 Abstract:In this paper, we analyze the sum-rate capacity of two-user Poisson multiple access channels (MAC), when the receiver is equipped with single antenna. We first characterize the sum-rate capacity of the non-symmetric Poisson MAC when each transmitter has a single antenna. While the sum-rate capacity of the symmetric Poisson MAC with single antenna at each transmitter has been characterized in the literature, the special property exploited in the existing method for the symmetric case does not hold for the non-symmetric channel anymore. We obtain the optimal input that achieves the sum-rate capacity by solving a non-convex optimization problem. We show that, for certain channel parameters, it is optimal for a single user to transmit to achieve the sum-rate capacity. This is in sharp contrast to the Gaussian MAC, in which both users must transmit, either simultaneously or at different times, in order to achieve the sum-rate capacity. We then characterize the sum-rate capacity of the Poisson multiple-input single-output (MISO) MAC with multiple antennas at each transmitter and single antenna at the receiver. By converting a non-convex optimization problem with a large number of variables into a non-convex optimization problem with two variables, we show that the sum-rate capacity of the Poisson MISO MAC with multiple transmit antennas is equivalent to a properly constructed Poisson MAC with a single antenna at each transmitter. Autors: Ain-ul-Aisha;Lifeng Lai;Yingbin Liang;Shlomo Shamai Shitz; Appeared in: IEEE Transactions on Information Theory Publication date: Oct 2017, volume: 63, issue:10, pages: 6457 - 6473 Publisher: IEEE
» On the Validity of an Analytical Solution for Characterizing Backscattering From Tree Trunks for FOPEN Sensing at $P$ -Band
 Abstract:A comprehensive set of simulations is performed to analyze the accuracy of an analytical solution for characterizing the backscattering responses of circular cylindrical tree trunks located above a dielectric ground. The formulation of interest here is from the volumetric current integration method, combined with a ray-based approach for the treatment of ground effects. Through comparisons with a reference solution provided by a full-wave solver, the region of validity of the closed-form approximate solution as a function of trunk length, trunk radius, incidence angle, and polarization is derived. Trunks with and without tapering along their lengths are considered. It is noted that, in general, the error behavior of the vv solution exhibits more complexity than that of the hh solution, due to the Brewster angle effects of the trunk and the ground; consequently, the hh solution is valid over a wider range of length and radius values. The backscattering signatures of the trunks are also examined in the imaging domain. It is found that the analytical solution can correctly predict the single ground-bounce returns but may not consistently capture other less prominent effects, such as scattering from the top of the trunk and higher order interactions. Autors: DaHan Liao; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5639 - 5644 Publisher: IEEE
» On Turing Instability in Nonhomogeneous Reaction-Diffusion CNN’s
 Abstract:Several results on instability in nonhomogeneous architectures able to generate Turing patterns are presented. The approach makes use of the continuity theorem regarding the dependence of polynomial roots on coefficients and of the root-locus techniques for small, and large parameter deviations from their homogeneous values, respectively. The results are valid for any linearized nonhomogeneous discrete model capable of generating Turing patterns. Autors: Liviu Goras;Paul Ungureanu;Leon O. Chua; Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers Publication date: Oct 2017, volume: 64, issue:10, pages: 2748 - 2760 Publisher: IEEE
» On-Chip ESD Protection Device for High-Speed I/O Applications in CMOS Technology
 Abstract:The diode operated under forward-biased condition has been widely used as an on-chip electrostatic discharge (ESD) protection device for high-speed circuits to sustain high ESD robustness, but the parasitic capacitance of diode may bring a negative impact to the circuits operating at higher speed. The ESD protection design with low parasitic capacitance has been strongly requested in high-speed I/O applications. The traditional methods to reduce parasitic capacitance were using a stacked diode or a stacked diode with embedded silicon-controlled rectifier (SCR). The stacked diode or the stacked diode with embedded SCR would have larger turn-on resistance to cause a higher clamping voltage. It should be further improved to achieve good ESD protection effectiveness for the high-speed I/O applications. In this paper, a new ESD protection device with reduced parasitic capacitance and smaller turn-on resistance to improve ESD protection effectiveness is proposed. The measurement results from the silicon chip have demonstrated that the proposed ESD device can achieve smaller parasitic capacitance, lower turn-on resistance, and higher ESD robustness, compared with the conventional devices. The proposed ESD protection device is very suitable to protect the high-speed I/O circuits in nanoscale CMOS technology. Autors: Jie-Ting Chen;Chun-Yu Lin;Ming-Dou Ker; Appeared in: IEEE Transactions on Electron Devices Publication date: Oct 2017, volume: 64, issue:10, pages: 3979 - 3985 Publisher: IEEE
» On-Demand Disassembly of Paramagnetic Nanoparticle Chains for Microrobotic Cargo Delivery
 Abstract:Paramagnetic nanoparticles are considered as attractive building blocks, particularly for robotic delivery of drugs. Although paramagnetic nanoparticles can be effectively gathered and transported using external magnetic fields, the disassembly process is yet to be fully investigated to avoid the formation of aggregations. In this paper, we report a novel method of controllable disassembly of paramagnetic nanoparticle chains using a predefined dynamic magnetic field. The dynamic field is capable of performing spreading and fragmentation of the particle chains simultaneously. Using the magnetic dipole–dipole repulsive forces, the final area covered by the particle chains swells up to 545% of the initial area. The final length distribution presents a strong relationship with the frequency of the dynamic field in deionized (DI) water and two kinds of biofluids. An analytical model of phase lag is proposed, which shows good agreement with the experimental results. Furthermore, we also present an assembly process using a rotating magnetic field, indicating that the assembly disassembly process is reversible. In addition, batch-cargo delivery of polystyrene microbeads using the nanoparticle chains as swarm-like nanorobots is demonstrated. Autors: Jiangfan Yu;Tiantian Xu;Zheyu Lu;Chi Ian Vong;Li Zhang; Appeared in: IEEE Transactions on Robotics Publication date: Oct 2017, volume: 33, issue:5, pages: 1213 - 1225 Publisher: IEEE
» Online Combination of EPID & Cherenkov Imaging for 3-D Dosimetry in a Liquid Phantom
 Abstract:Online acquisition of Cherenkov and portal imaging data was combined with a reconstruction scheme called EC3-D, providing a full 3-D dosimetry of megavoltage X-ray beams in a water tank. The methodology was demonstrated and quantified in a single static beam. Furthermore, the dynamics and visualization of the 3-D dose reconstruction were demonstrated with a volumetric modulated arc therapy plan for TG-119 C-Shape geometry. The developed algorithm combines depth dose information, provided by Cherenkov images, with the lateral dose distribution, provided by the electronic portal imaging device. The strength of our approach lies in the acquisition of both imaging data streams with sub-millimeter theoretical resolution at 5-Hz frame-rate, which can be concurrently processed by the fast Fourier transform-based analysis, thus providing means for an efficient real-time 3-D dosimetry. Autors: Petr Bruza;Jacqueline M. Andreozzi;David J. Gladstone;Lesley A. Jarvis;Joerg Rottmann;Brian W. Pogue; Appeared in: IEEE Transactions on Medical Imaging Publication date: Oct 2017, volume: 36, issue:10, pages: 2099 - 2103 Publisher: IEEE
» Online Identification of Power System Equivalent Inertia Constant
 Abstract:This paper proposes a closed-loop identification method to estimate the equivalent inertia constant of a power system at the connection bus. A microperturbation is first performed with a well-designed multisine signal probed through any power electronic devices in the internal system. Then, responses of frequency and active power measured by the phase measurement unit at the connection bus are used for the closed-loop identification. Compared to the conventional transient signal based method, the proposed method has simple implementation and minimum impacts on the system security, and thus could be carried out in real-time to identify the time-varying and nonlinear equivalent inertia constant in modern power systems with complex heterogeneous components. The effectiveness of the proposed method is validated in an 8-generator 36-bus simulation system and an actual power system. Autors: Junbo Zhang;Hanchen Xu; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8098 - 8107 Publisher: IEEE
» Online Monitoring and Diagnosis of HV Cable Faults by Sheath System Currents
 Abstract:Cross-bonded metal sheath connection is applied in sectioned single-core power cables to reduce or eliminate the voltages that are induced in the sheath over long distances. However, cross-bonded cables present an opportunity as well as a challenge for online measurement and diagnosis of cable conditions. In this paper, a methodology to identify cable sheath faults through analysis of the sheath system currents in a cross-bonded cable system is presented. First, a numerical model is established to simulate the sheath currents in cross-bonded cable systems. Second, analyses of several faults, which happen frequently with serious consequences, are presented on the basis of current measurement at the link cable. Simulations of normal and fault conditions are given to determine the feasibility of fault diagnosis. A case study using field data from a cable tunnel in China considering the normal condition is presented to verify the numerical model. Results in normal condition show good consistency with field data with error less than 5%. Simulation results of fault conditions show that analysis of readings from six current sensors can distinguish different fault types and fault positions using the method proposed. Based on the analyses, criteria are established for sheath loop fault type diagnosis. Autors: Xiang Dong;Yang Yang;Chengke Zhou;Donald M. Hepburn; Appeared in: IEEE Transactions on Power Delivery Publication date: Oct 2017, volume: 32, issue:5, pages: 2281 - 2290 Publisher: IEEE
» Online Optimization of Interference Coordination Parameters in Small Cell Networks
 Abstract:This paper focuses on interference coordination between the small cell and macro cell tiers of a wireless access network. We present a self-optimization mechanism for LTE-A eICIC parameters (CRE bias and ABS ratio) following a novel approach based on a model-free learning strategy, not requiring any previous knowledge about the network (e.g., topology, interference graph, and scheduling algorithms). Our proposal is built upon a stochastic optimization algorithm known as response surface methodology (RSM), that we use to find efficient eICIC configurations during network operation (online learning), adapting to changing network conditions, such as traffic or user distribution. The objective consists of optimizing a performance metric for which, in general, mathematical expression is unavailable. In particular, we consider the fifth percentile throughput defined by the 3GPP. By means of RSM, our mechanism obtains local approximations of the objective function to perform steepest ascent iterations with an adjustable level of statistical accuracy. The algorithm can be extended to account for stochastic constraints, allowing the network to optimize one performance metric while maintaining other metrics above a desired level. Autors: Jose A. Ayala-Romero;Juan J. Alcaraz;Javier Vales-Alonso;Esteban Egea-López; Appeared in: IEEE Transactions on Wireless Communications Publication date: Oct 2017, volume: 16, issue:10, pages: 6635 - 6647 Publisher: IEEE
» Online QoS Prediction for Runtime Service Adaptation via Adaptive Matrix Factorization
 Abstract:Cloud applications built on service-oriented architectures generally integrate a number of component services to fulfill certain application logic. The changing cloud environment highlights the need for these applications to keep resilient against QoS variations of their component services so that end-to-end quality-of-service (QoS) can be guaranteed. Runtime service adaptation is a key technique to achieve this goal. To support timely and accurate adaptation decisions, effective and efficient QoS prediction is needed to obtain real-time QoS information of component services. However, current research has focused mostly on QoS prediction of working services that are being used by a cloud application, but little on predicting QoS values of candidate services that are equally important in determining optimal adaptation actions. In this paper, we propose an adaptive matrix factorization (namely AMF) approach to perform online QoS prediction for candidate services. AMF is inspired from the widely-used collaborative filtering techniques in recommender systems, but significantly extends the conventional matrix factorization model with new techniques of data transformation, online learning, and adaptive weights. Comprehensive experiments, as well as a case study, have been conducted based on a real-world QoS dataset of Web services (with over 40 million QoS records). The evaluation results demonstrate AMF’s superiority in achieving accuracy, efficiency, and robustness, which are essential to enable optimal runtime service adaptation. Autors: Jieming Zhu;Pinjia He;Zibin Zheng;Michael R. Lyu; Appeared in: IEEE Transactions on Parallel and Distributed Systems Publication date: Oct 2017, volume: 28, issue:10, pages: 2911 - 2924 Publisher: IEEE
» Online-Learning-Based Mode Prediction Method for Quality Scalable Extension of the High Efficiency Video Coding (HEVC) Standard
 Abstract:SHVC, the scalable extension of High Efficiency Video Coding (HEVC), uses advanced inter-layer prediction features in addition to the advanced compression tools of HEVC to improve the compression performance. Using combined features has brought us improved compression performance at the cost of huge computational complexity for the SHVC encoder. This complexity is mainly because of the the inter/intra-prediction mode search of the coding units. The focus of this study is on developing an efficient complexity reduction for quality scalability of SHVC encoder, with the intention to facilitate the adoption of SHVC for real-time applications. In this regard, first, we build a probabilistic model that uses the mode information and motion homogeneity of already encoded blocks in the enhancement layer (EL) and the base layer to predict the probabilities of all the available inter/intra modes of the to-be-coded block in the EL. Then, we propose an online-learning-based fast mode, assigning (FMA) method that uses the proposed probabilistic model to predict the mode of the to-be-coded block in the EL. Performance evaluation shows that our proposed FMA method reduces the total execution time of the SHVC encoder by 45.40% on average compared with unmodified SHVC codec while maintaining the overall video quality. Autors: Hamid Reza Tohidypour;Hossein Bashashati;Mahsa T. Pourazad;Panos Nasiopoulos; Appeared in: IEEE Transactions on Circuits and Systems for Video Technology Publication date: Oct 2017, volume: 27, issue:10, pages: 2204 - 2215 Publisher: IEEE
» Onto a Skewness Approach to the Generalized Curvature Ocean Surface Scattering Model
 Abstract:The generalized curvature ocean surface scattering model [general curvature model (GCM)] is extended and revisited. Two key steps are addressed in this paper, namely, a necessary sea surface spectrum undressing procedure and the inclusion of a skewness phase-related component. Normalized radar cross-section (NRCS) simulations are generated at C-band for various wind conditions, polarizations, and incidence angles. Results are compared with CMOD5.n. Although the sea surface spectrum undressing procedure is a necessary step, the overall NRCS dynamic is notably affected only in low wind conditions (≤5 m/s). The inclusion of the skewness phase-related component makes the most impact to the NRCS dynamic where the upwind/downwind asymmetry is clearly detectable. A good agreement between the upwind/downwind asymmetry of the extended GCM and CMOD5.n is achieved for moderate winds (≈5–10 m/s) and moderate incidence angles (≈32°–40°). For low incidence angles (<26°), the GCM tends to overestimate the upwind/downwind asymmetry compared with CMOD5.n. Autors: Faozi Saïd;Harald Johnsen;Frédéric Nouguier;Bertrand Chapron;Geir Engen; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Oct 2017, volume: 55, issue:10, pages: 5843 - 5853 Publisher: IEEE
» Opportunities for Energy Storage: Assessing Whole-System Economic Benefits of Energy Storage in Future Electricity Systems
 Abstract:Any Cost-effective transition toward low-carbon electricity supply will necessitate improved system flexibility to address the challenges of increased balancing requirements and degradation in asset use. Energy storage (ES) represents a flexible option that can bring significant, fundamental economic benefits to various areas in the electric power sector, including reduced investment requirements for generation, transmission, and distribution infrastructure as well as reduced system operation and balancing costs. The additional flexibility offered by ES could also significantly reduce the requirement for investment in low-carbon generation capacity while achieving the established carbon intensity targets. Moreover, ES may present significant option value, as it can provide flexibility for dealing with uncertainty in future system development. Autors: Goran Strbac;Marko Aunedi;Ioannis Konstantelos;Roberto Moreira;Fei Teng;Rodrigo Moreno;Danny Pudjianto;Adriana Laguna;Panagiotis Papadopoulos; Appeared in: IEEE Power and Energy Magazine Publication date: Oct 2017, volume: 15, issue:5, pages: 32 - 41 Publisher: IEEE
» Optical Frequency Comb Generation Based on Dual-Polarization IQ Modulator Shared by Two Polarization-Orthogonal Recirculating Frequency Shifting Loops
 Abstract:A novel optical frequency comb generator (OFCG) based on a dual-polarization IQ modulator shared by two polarization-orthogonal recirculating frequency shifting (RFS) loops has been proposed. The states of polarization of two optical subcombs output from the respective loops are kept orthogonal in the proposed scheme. More than 80 carriers, whose carrier-to-noise ratio (CNR) can be further improved with better conditions, have been demonstrated experimentally. Meanwhile, the number and frequency spacing of the carriers of both the two optical subcombs can be easily tuned due to the unique feature of flexible controls, which is different from the previous dual-RFS-loop-based OFCG in which the carrier frequency spacing must be kept fixed. Based on the theoretical and experimental results, the proposed scheme has the advantages of good feasibility, tunability, and flexibility, which can find the potential applications in various fields. Autors: Jianping Li;Huatao Ma;Zhaohui Li;Xiaoguang Zhang; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 10 Publisher: IEEE
» Optical Power Monitoring with Ultrahigh Sensitivity in Silicon Waveguides and Ring Resonators
 Abstract:We demonstrate optical power monitoring using a silicon resistor enabled by the surface and defect states-induced photoconductance effect. Ultrahigh optical power detection sensitivity of −40 dBm under a low AC drive voltage of 5 mV is obtained with the facilitation of a lock-in amplifier circuitry. The detection scheme is applied to monitor the resonances in single and coupled-ring resonators. Intracavity resonance spectrum is successfully measured at both the static and the thermal tuning conditions. The demonstration opens a compelling new way for nonintrusive on-chip optical power detection by exploiting doped silicon resistor-based thermooptic heaters. Autors: Dong Li;Linjie Zhou;Liangjun Lu;Jianping Chen; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 10 Publisher: IEEE
» Optical–Optical Synchronization Between Two Independent Femtosecond Yb-Fiber Lasers With 10 –20 Instability in 105 s
 Abstract:Optical–optical synchronization between independent mode-locked lasers with attosecond timing precision is essential for arbitrary electric-field waveform generation, subcycle optical pulse synthesis, optical frequency transfer as well as next-generation photon-science facilities, e.g., X-ray free-electron lasers. Long-term stable operation with low timing drift is highly desired for all above applications. Here, we present a five-day uninterrupted timing synchronization between two independent femtosecond Yb-fiber lasers via balanced optical correlation method. The out-of-loop residual timing drift over the entire time frame reaches 733 as rms, corresponding to instability at . To the best of our knowledge, it is the first characterization of 105 s instability for subfemtosecond optical–optical synchronization based on mode-locked lasers. Autors: Haochen Tian;Youjian Song;Jiahe Yu;Haosen Shi;Minglie Hu; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 7 Publisher: IEEE
» Optically-Pumped Single-Mode Deep-Ultraviolet Microdisk Lasers With AlGaN-Based Multiple Quantum Wells on Si Substrate
 Abstract:In this work, we report demonstration of optically-pumped single-mode deep-ultraviolet lasing actions operating at room temperature from ∼1-μm 150-nm-thick undercut microdisks with AlN/Al0.35Ga 0.65N (5.5 nm/2.5 nm) multiple quantum wells. These AlGaN-based microdisks are grown on Si substrate by metal-organic chemical vapor deposition. The lasing wavelength centers at ∼300.1 nm with the linewidth of ∼1.0 nm as the excitation exceeds the lasing threshold of ∼24.2 mJ/cm2. An emission coupling factor (β) of 9.2 × 10−2 is estimated based on the light output characteristics of the AlN/AlGaN microdisks with increasing the pumping densities. Concurrently, a 100 meV blue-shift in the mode energy has also been observed. The lasing spectral peak is attributed to fundamental-order transverse-electric whispering-gallery modes, confirmed by three-dimensional finite-difference time-domain simulations. Autors: Yiyun Zhang;Hongjian Li;Panpan Li;Arash Dehzangi;Liancheng Wang;Xiaoyan Yi;Guohong Wang; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 8 Publisher: IEEE
» Optimal Aircraft Planar Navigation in Static Threat Environments
 Abstract:We consider the problem of navigating a military aircraft in a threat environment to its final destination while minimizing the maximum threat level and the length of the aircraft path. The proposed method to construct optimal low-risk aircraft paths involves a simple geometric procedure and is very computationally efficient. The effectiveness of the developed algorithm is illustrated by a number of examples and comparisons with a fuzzy logic based algorithm. Autors: Andrey V. Savkin;Hailong Huang; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2413 - 2426 Publisher: IEEE
» Optimal Beamforming for Gaussian MIMO Wiretap Channels With Two Transmit Antennas
 Abstract:A Gaussian multiple-input multiple-output wiretap channel in which the eavesdropper and legitimate receiver are equipped with arbitrary numbers of antennas and the transmitter has two antennas is studied in this paper. The input covariance matrix that achieves the secrecy capacity is determined. In particular, it is shown that the secrecy capacity of this channel can be achieved by linear precoding. Precoding and power allocation schemes that maximize the achievable secrecy rate, and thus achieve the secrecy capacity, are developed. The secrecy capacity is then compared with the achievable secrecy rate of generalized singular value decomposition (GSVD)-based precoding, which is the best previously proposed technique for this problem. Numerical results demonstrate that substantial gain can be obtained in secrecy rate between the proposed and GSVD-based precodings. Autors: Mojtaba Vaezi;Wonjae Shin;H. Vincent Poor; Appeared in: IEEE Transactions on Wireless Communications Publication date: Oct 2017, volume: 16, issue:10, pages: 6726 - 6735 Publisher: IEEE
» Optimal Broadband Noise Matching to Inductive Sensors: Application to Magnetic Particle Imaging
 Abstract:Inductive sensor-based measurement techniques are useful for a wide range of biomedical applications. However, optimizing the noise performance of these sensors is challenging at broadband frequencies, owing to the frequency-dependent reactance of the sensor. In this work, we describe the fundamental limits of noise performance and bandwidth for these sensors in combination with a low-noise amplifier. We also present three equivalent methods of noise matching to inductive sensors using transformer-like network topologies. Finally, we apply these techniques to improve the noise performance in magnetic particle imaging, a new molecular imaging modality with excellent detection sensitivity. Using a custom noise-matched amplifier, we experimentally demonstrate an 11-fold improvement in noise performance in a small animal magnetic particle imaging scanner. Autors: Bo Zheng;Patrick W. Goodwill;Neerav Dixit;Di Xiao;Wencong Zhang;Beliz Gunel;Kuan Lu;Greig C. Scott;Steven M. Conolly; Appeared in: IEEE Transactions on Biomedical Circuits and Systems Publication date: Oct 2017, volume: 11, issue:5, pages: 1041 - 1052 Publisher: IEEE
» Optimal Control of State-Dependent Service Rates in a MAP/M/1 Queue
 Abstract:In this paper, we study the optimal control of service rates in a queueing system with a Markovian arrival process (MAP) and exponential service times. The service rate is allowed to be state dependent, i.e., we can adjust the service rate according to the queue length and the phase of the MAP. The cost function consists of holding cost and operating cost. The goal is to find the optimal service rates that minimize the long-run average total cost. To achieve that, we use the matrix-analytic methods (MAM) together with the sensitivity-based optimization (SBO) theory. A performance difference formula is derived, which can quantify the difference of the long-run average total cost under any two different settings of service rates. Based on the difference formula, we show that the long-run average total cost is monotone in the service rate and the optimal control is a bang–bang control. We also show that, under some mild conditions, the optimal control policy of service rates is of a quasi-threshold-type. By utilizing the MAM theory, we propose a recursive algorithm to compute the value function related quantities. An iterative algorithm to efficiently find the optimal policy, which is similar to policy iteration, is proposed based on the SBO theory. We further study some special cases of the problem, such as the optimality of the threshold-type policy for the M/M/1 queue. Finally, a number of numerical examples are presented to demonstrate the main results and explore the impact of the phase of the MAP on the optimization in the MAP/M/1 queue. Autors: Li Xia;Qi-Ming He;Attahiru Sule Alfa; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 4965 - 4979 Publisher: IEEE
» Optimal Datalink Selection for Future Aeronautical Telecommunication Networks
 Abstract:Modern aeronautical telecommunication networks (ATN) make use of different simultaneous datalinks to deliver robust, secure, and efficient ATN services. This paper proposes a multiple attribute decision making based optimal datalink selection algorithm, which considers different attributes including safety, QoS, costs, and user/operator preferences. An intelligent TRigger-based aUtomatic Subjective weighTing (i-TRUST) method is also proposed for computing subjective weights necessary to provide user flexibility. Simulation results demonstrate that the proposed algorithm significantly improves the performance of the ATN system. Autors: Atm S. Alam;Yim-Fun Hu;Prashant Pillai;Kai Xu;Jim Baddoo; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2502 - 2515 Publisher: IEEE
» Optimal Definition of Class F for Realistic Transistor Models
 Abstract:An optimal three-harmonic definition of class F at the intrinsic level is presented for realistic transistor models exhibiting IV characteristics with a nonzero knee voltage. This updated class-F definition is needed for use with the recently reported embedding device model, which predicts in a single harmonic balance simulation the voltage and current waveforms required at the package reference planes to sustain an intrinsic mode of operation. Optimal class-F operation is obtained by setting to infinite the third-harmonic output impedance of the transistor IV characteristics instead of using an open load for the third-harmonic termination. This is achieved by fine tuning the class-F quasi-rectangular drain voltage waveform. The required third-harmonic component of the drain voltage in the optimal class F is then found to be generated by the lossless inductive termination of the third-harmonic component of the drain displacement current arising from the nonlinear drain-to-source capacitance. The proposed class-F definition is verified for a gallium nitride (GaN) high electron mobility transistor using third-harmonic load–pull simulations with a realistic GaN transistor model. The optimal third-harmonic load termination predicted using the class-F definition is found to be in full agreement with the one obtained from the drain efficiency contour plots. A close agreement is also obtained for the predicted and measured optimal third-harmonic load termination, bringing experimental support for the proposed class-F definition. Autors: Francisco J. Martinez-Rodriguez;Patrick Roblin;Zoya Popovic;Jose I. Martinez-Lopez; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Oct 2017, volume: 65, issue:10, pages: 3585 - 3595 Publisher: IEEE
» Optimal Demand Response Bidding and Pricing Mechanism With Fuzzy Optimization: Application for a Virtual Power Plant
 Abstract:In this paper, a virtual power plant (VPP) that consists of generation, both renewable and conventional, and controllable demand is enabled to participate in the wholesale markets. The VPP makes renewable energy sources (RES) and distributed generations controllable and observable to the system operator. The main objective is to introduce a framework that optimizes the bidding strategies and maximizes the VPP's profit on day-ahead and real-time bases. To achieve this goal, the VPP trades energy externally with a wholesale market, and trades energy and demand response (DR) internally with the consumers in its territory. That is, when generation exceeds demand, the VPP sells the excess energy to the market, and it buys energy from the market when the generation and reduction in demand due to DR scheme are less than the required demand in its territory. Both load curtailment and load shift are modeled. For the day-ahead internal VPP market, fuzzy optimization is proposed to consider the uncertainty in the RES. Comparison results with deterministic and probabilistic optimizations demonstrate the effectiveness of the fuzzy approach in terms of achieving higher realized profits with reasonable computation effort. It is also shown that considering uncertainties in the optimization can result in reduced dependence on the conventional generator. Autors: Ali T. Al-Awami;Nemer A. Amleh;Ammar M. Muqbel; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 5051 - 5061 Publisher: IEEE
» Optimal Design of Semi-Orthogonal Multiple-Access Massive MIMO Systems
 Abstract:We study an uplink scenario of single-cell multi-user massive multiple-input multiple-output (mMIMO) communication systems with a semi-orthogonal multiple-access (SOMA), where the channel state information is acquired by transmitting uplink pilot signals superimposed on uplink data signals. We analytically find the optimal resource allocation parameters; e.g., pilot and data transmit power and training duration, which maximize achievable sum-rates by minimum mean-square error (MMSE) channel estimation and maximum ratio combining (MRC) for data detection. Our results indicate that the optimized SOMA encouragingly outperforms the optimized conventional time-division duplex protocol in terms of both energy- and spectral efficiency. Autors: Amirreza Kabiri;Mohammad Javad Emadi;Majid Nasiri Khormuji; Appeared in: IEEE Communications Letters Publication date: Oct 2017, volume: 21, issue:10, pages: 2230 - 2233 Publisher: IEEE
» Optimal Power Allocation Scheme for Non-Orthogonal Multiple Access With $\alpha$ -Fairness
 Abstract:This paper investigates the optimal power allocation scheme for sum throughput maximization of non-orthogonal multiple access (NOMA) system with -fairness. In contrast to the existing fairness NOMA models, -fairness can only utilize a single scalar to achieve different user fairness levels. Two different channel state information at the transmitter (CSIT) assumptions are considered, namely, statistical and perfect CSIT. For statistical CSIT, fixed target data rates are predefined, and the power allocation problem is solved for sum throughput maximization with -fairness, through characterizing several properties of the optimal power allocation solution. For perfect CSIT, the optimal power allocation is determined to maximize the instantaneous sum rate with -fairness, where user rates are adapted according to the instantaneous channel state information (CSI). In particular, a simple alternate optimization algorithm is proposed, which is demonstrated to yield the optimal solution. Numerical results reveal that, at the same fairness level, NOMA significantly outperforms the conventional orthogonal multiple access for both the scenarios with statistical and perfect CSIT. Autors: Peng Xu;Kanapathippillai Cumanan; Appeared in: IEEE Journal on Selected Areas in Communications Publication date: Oct 2017, volume: 35, issue:10, pages: 2357 - 2369 Publisher: IEEE
» Optimal Protection Coordination for Microgrids Considering N $-$1 Contingency
 Abstract:Usually, protection coordination problems are solved under the assumption that the network topology is fixed. Yet, in practice, any power system can encounter changes in the network topology due to transient events. These transient events can be in the form of line or generation source outage. Furthermore, in the presence of distributed generation, the network topology can change depending on whether the system is operating in the grid-connected or islanded mode. Thus, it is essential to consider all possible network topologies while designing a protection scheme for distribution systems with distributed generation (DG). In this paper, the protection coordination problem is solved to determine the optimal relay settings considering N1 contingency, which can result from a single line, DG unit, or substation outage. In addition, the relays are designed taking into account both grid-connected and islanded operation modes. The problem has been formulated as a mixed integer nonlinear programming problem including coordination constraints corresponding to the various possible outages. The proposed approach is tested on a 9-bus radial distribution system and on the IEEE 14-bus meshed distribution system, both equipped with DG units. Autors: Khaled A. Saleh;Hatem H. Zeineldin;Ehab F. El-Saadany; Appeared in: IEEE Transactions on Industrial Informatics Publication date: Oct 2017, volume: 13, issue:5, pages: 2270 - 2278 Publisher: IEEE
» Optimal Stochastic Design of Wind Integrated Energy Hub
 Abstract:This study presents a stochastic approach to design a wind integrated energy hub with multiple energy systems. Energy hub system offers significant advantages to energy services by providing the flexibility to cope with the challenging effects of intermittent renewable energy sources penetration. To this end, the wind integrated energy hub design problem would optimally determine appropriate number and size of system components that satisfy electricity and thermal demand and system constraints. To secure operation, the reliability indices such as the loss-of-load expectation and the expected energy not supplied are considered. The wind power generation and load forecasting uncertainties as well as the random outages of components are modeled as a scenario using proper scenario generation methods. The scenario reduction technique is also introduced to reduce the computational burden of the scenario-based design model. Finally, the proposed model is applied to a test case to illustrate effectiveness of the proposed approach. Autors: Amirhossein Dolatabadi;Behnam Mohammadi-ivatloo;Mehdi Abapour;Sajjad Tohidi; Appeared in: IEEE Transactions on Industrial Informatics Publication date: Oct 2017, volume: 13, issue:5, pages: 2379 - 2388 Publisher: IEEE
» Optimal-Vector-Based Algorithm for Solving Min-Max Programming Subject to Addition-Min Fuzzy Relation Inequality
 Abstract:Optimal management model in BitTorrent-like peer-to-peer (P2P) file sharing system can be reduced into a min–max programming problem subject to addition-min fuzzy relation inequality. To deal with such problem, we introduce the concept of optimal vector. Besides, a novel optimal-vector-based (OVB) algorithm is developed to find a minimal optimal solution. Based on practical application consideration, solution obtained by the OVB algorithm is theoretically demonstrated to be better than or equal to that obtained by the existing method. Advantage of our proposed OVB algorithm is illustrated by detailed numerical examples. Autors: Xiao-Peng Yang; Appeared in: IEEE Transactions on Fuzzy Systems Publication date: Oct 2017, volume: 25, issue:5, pages: 1127 - 1140 Publisher: IEEE
» Optimization and Design of Wireless Systems for the Implementation of Context Aware Scenarios in Railway Passenger Vehicles
 Abstract:In this paper, intra-wagon wireless communication performance is analyzed, in order to account for inherent scenario complexity in the deployment phase of wireless systems toward the implementation of a context-aware environment. A real commercial passenger wagon has been simulated by means of an in-house-developed 3-D ray launching code, accounting for embedded wagon elements as well as variable user densities within the passenger wagon. Onboard measurements of a designed and deployed wireless sensor network are obtained, showing good agreement with wireless channel estimations for two different frequencies of operation. Energy consumption behavior and user density impact have also been analyzed and estimated as a function of network topology and the operational mode. These results can aid in wireless transceivers deployment configurations, in order to minimize power consumption, optimize interference levels, and increase overall service performance. Autors: Leyre Azpilicueta;José Javier Astrain;Peio Lopez-Iturri;Fausto Granda;Cesar Vargas-Rosales;Jesús Villadangos;Asier Perallos;Alfonso Bahillo;Francisco Falcone; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Oct 2017, volume: 18, issue:10, pages: 2838 - 2850 Publisher: IEEE
» Optimization of a Wireless Power Transfer System With a Repeater Against Load Variations
 Abstract:Power transfer efficiency (PTE) and transferred power (TP) are the key performance indices for the design of wireless power transfer (WPT) systems. An optimization method for WPT system with the use of a repeater is presented to enhance both PTE and TP. A tuning technique is investigated for the performance improvement against load variations. The self-resonance frequencies of transmitter, receiver, and repeater coils, and the operating frequency can be optimized to improve the load characteristics. The analytical approach presented in this paper is found to be capable of reaching the global optimum solution for a given design condition. Theoretical analysis is supported with the numerical and experimental results. Autors: Prasad Kumara Sampath Jayathurathnage;Arokiaswami Alphones;D. Mahinda Vilathgamuwa; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 7800 - 7809 Publisher: IEEE
» Optimization of the Source Power Usage in Spectral-Domain Optical Coherence Tomography
 Abstract:Source power consumption and system sensitivity of a spectrometer-based optical coherence tomography (SD-OCT) system are investigated. Our study shows that the performance of an SD-OCT system can be classified into two categories based on the beam-splitting ratio R between the sample and reference rams in the Michelson interferometer. For the classic SD-OCT configuration, R is less than 1.0, and the improvement of the sample light collection efficiency through reducing R will increase the cost of OCT source power. We find that through combining the detection and source arms of a Michelson interferometer together with a fiber optic circulator and choosing a beam splitter with R > 1.0, OCT source power can be reduced greatly without losing the system sensitivity. Light squandered in the reference arm is minimized, and efficiencies of source power usage and sample light collection can be improved at the same time. Further analysis shows that the optimized signal-to-noise ratio of our approach is higher than that of the classic SD-OCT system. Measured sensitivity of our SD-OCT setup is 98.56 dB when the source power is 1.38 mW. Chicken trachea and heart are imaged successfully in vitro. Autors: Yimin Wang;Xiangyang Zhang;Xiaobing Chen;Zhong Chen; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 10 Publisher: IEEE
» Optimization of Wireless Power Transfer Systems Enhanced by Passive Elements and Metasurfaces
 Abstract:This paper presents a rigorous optimization technique for wireless power transfer (WPT) systems enhanced by passive elements, ranging from simple reflectors and intermediate relays all the way to general electromagnetic guiding and focusing structures, such as metasurfaces and metamaterials. At its core is a convex semidefinite relaxation formulation of the otherwise nonconvex optimization problem, of which tightness and optimality can be confirmed by a simple test of its solutions. The resulting method is rigorous, versatile, and general—it does not rely on any assumptions. As shown in various examples, it is able to efficiently and reliably optimize such WPT systems in order to find their physical limitations on performance, optimal operating parameters, and inspect their working principles, even for a large number of active transmitters and passive elements. Autors: Hans-Dieter Lang;Costas D. Sarris; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5462 - 5474 Publisher: IEEE
» Optimization-Based AC Microgrid Synchronization
 Abstract:This paper casts the synchronization phenomena in inverter-based ac microgrids as an optimization problem solved using alternating direction method of multipliers (ADMM). Existing cooperative control techniques are based on the standard voting protocols in multiagent systems, and assume ideal communication among inverters. Alternatively, this paper presents a recursive algorithm to restore synchronization in voltage and frequency using ADMM, which results in a more robust secondary control even in the presence of noise. The performance of the control algorithm, for an islanded microgrid test system with additive noise in communication links broadcasting reference signals and communication links connecting neighboring inverters, is evaluated for a modified IEEE 34-bus feeder system. An upper bound for the deviation due to communication noise from the reference set point is analytically derived and verified by the simulated microgrid test system. Autors: Shankar Abhinav;Ioannis D. Schizas;Frank Ferrese;Ali Davoudi; Appeared in: IEEE Transactions on Industrial Informatics Publication date: Oct 2017, volume: 13, issue:5, pages: 2339 - 2349 Publisher: IEEE
» Optimization-Based Synthesis of Photonic IIR Filters Accounting for Internal Losses in Microresonators
 Abstract:We present a new optimization-based approach for synthesizing photonic infinite impulse response filters formed using microresonators. Taking into account the finite internal losses in these resonators, we cast the synthesis of filter coefficients as a semidefinite programming problem designed to restrict root-magnitudes set by the internal loss, while meeting filter-mask specifications. We provide a discussion on the formulation of the algorithm, and show how it can be used to design the optical components in a second-order unit cell. In addition, we provide an example of forming a fourth-order low-pass filters by cascading two unit cells. Our simulations show that fourth-order low-pass filters can achieve band-rejection ratios of 60 dB with integrated microresonators that possess an intrinsic quality-factor Q0 of . Autors: B. Limketkai;W. Ng;T. Rockwood; Appeared in: Journal of Lightwave Technology Publication date: Oct 2017, volume: 35, issue:20, pages: 4459 - 4467 Publisher: IEEE
» Optimized Phase Disposition (PD) Modulation of a Modular Multilevel Converter
 Abstract:This paper presents a theoretical harmonic analysis of phase disposition (PD) and phase-shifted carrier pulse-width modulation strategies for modular multilevel converters (MMCs). It is shown that when these strategies are implemented on a per MMC arm basis, their spectral performances converge because of cancellation of odd carrier sideband groups between each phase leg's arms. An improved PD modulation strategy is then presented that uses a single PD modulator for the entire phase leg, followed by a state machine decoder that evenly distributes switching pulses to all submodules across the phase leg upper and lower arms to balance the distribution of submodule commutation events. The resulting strategy achieves optimum phase leg PD spectral performance and also achieves natural voltage balancing of the MMC submodules. All theoretical findings are supported by simulation and experimental results obtained using a five-level MMC prototype. Autors: Brendan Peter McGrath;Carlos Alberto Teixeira;Donald Grahame Holmes; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4624 - 4633 Publisher: IEEE
» Optimizing Itinerary Selection and Charging Association for Mobile Chargers
 Abstract:Wireless power transfer provides a promising way to extend the battery lifetime of our energy-hungry rechargeable devices. Previous studies have envisioned using mobile vehicles/robots/drones equipped with high capacity batteries as mobile chargers to replenish those devices, and they mainly focus on maximizing network lifetime, optimizing efficiency of charging scheduling, minimizing total charging delay, etc. However, existing methods may be insufficient and inflexible when the energy consumption of rechargeable devices fluctuates overtime, or when rechargeable devices are sparse. In this paper, we consider how to efficiently provide flexible wireless charging using pre-planned charging itineraries. We present the Itinerary Selection and Charging Association (ISCA) problem: given a set of rechargeable devices and a set of candidate charging itineraries, how can we select itineraries and determine a corresponding charging association to minimize the amount of energy which is due to mobile chargers' movement and wireless charging loss, so that every device gets its required energy. We prove that ISCA is NP-complete by reducing the set cover problem to it. We start solving this problem by first looking at the case in which an itinerary can only be used once, and we propose an algorithm with approximation ratio of O (lnM) and a practical heuristic algorithm, where M is the number of devices. For the general case in which an itinerary may be used multiple times, we propose an approximation algorithm of factor 10 using the Primal-Dual schema. Evaluations results from real field experiments and extensive simulations show that the proposed algorithms have near-optimal performance and PDA reduces the amount of wasted energy by up to 65 percent compared with a set cover-based algorithm. Autors: Sheng Zhang;Zhuzhong Qian;Jie Wu;Fanyu Kong;Sanglu Lu; Appeared in: IEEE Transactions on Mobile Computing Publication date: Oct 2017, volume: 16, issue:10, pages: 2833 - 2846 Publisher: IEEE
» Optimizing Opportunistic Routing in Asynchronous Wireless Sensor Networks
 Abstract:Asynchronous sleep schedule and geographical routing are two efficient and scalable solutions for wireless sensor networks (WSNs). However, the schedule may degrade the delay performance of the routing protocol, and the optimal combined utilization of these two solutions is still an open question. In this letter, we propose a geographical-based opportunistic routing protocol for asynchronous WSNs. Each node maintains multiple relay candidates that make geographical progresses of more than a threshold , and opportunistically forwards data packet to the first candidate that wakes up. We can obtain the optimal end-to-end delay performance, by just tuning . Analytical and simulation results show that the derived optimal can make a good tradeoff between the single-hop delay and the hop count of forwarding path, and minimize the end-to-end delay of forwarding path. Autors: Xinguo Wang;Xi Wu;Xinming Zhang; Appeared in: IEEE Communications Letters Publication date: Oct 2017, volume: 21, issue:10, pages: 2302 - 2305 Publisher: IEEE
» Optimizing Temperature Coefficient and Frequency Response of Rogowski Coils
 Abstract:This paper describes a new method for optimizing both Rogowski coil’s temperature coefficient and its high frequency response. The proposed scheme is based on finding a value for coil termination resistance and for its temperature coefficient, which result in negligible change of coil output voltage versus temperature while still allowing for any damping ratio desired. The method is tested in a proof-of-concept setup with an openable, rigid Rogowski coil. The result shows that a well-damped LC-resonance of the coil is possible without having to make a compromise with temperature coefficient and vice versa. The proof-of-concept measurement is done for a broad temperature range around room temperature and works for any range where the coil‘s temperature expansion is sufficiently linear. At the same time, the frequency response is preserved, giving an extension of at least an order of magnitude with respect to previous work. Autors: Tapio A. Lehtonen;Jari Hällström; Appeared in: IEEE Sensors Journal Publication date: Oct 2017, volume: 17, issue:20, pages: 6646 - 6652 Publisher: IEEE
» ORB-SLAM2: An Open-Source SLAM System for Monocular, Stereo, and RGB-D Cameras
 Abstract:We present ORB-SLAM2, a complete simultaneous localization and mapping (SLAM) system for monocular, stereo and RGB-D cameras, including map reuse, loop closing, and relocalization capabilities. The system works in real time on standard central processing units in a wide variety of environments from small hand-held indoors sequences, to drones flying in industrial environments and cars driving around a city. Our back-end, based on bundle adjustment with monocular and stereo observations, allows for accurate trajectory estimation with metric scale. Our system includes a lightweight localization mode that leverages visual odometry tracks for unmapped regions and matches with map points that allow for zero-drift localization. The evaluation on 29 popular public sequences shows that our method achieves state-of-the-art accuracy, being in most cases the most accurate SLAM solution. We publish the source code, not only for the benefit of the SLAM community, but with the aim of being an out-of-the-box SLAM solution for researchers in other fields. Autors: Raúl Mur-Artal;Juan D. Tardós; Appeared in: IEEE Transactions on Robotics Publication date: Oct 2017, volume: 33, issue:5, pages: 1255 - 1262 Publisher: IEEE
» Order-Controllable Cylindrical Vector Vortex Beam Generation by Using Spatial Light Modulator and Cascaded Metasurfaces
 Abstract:Cylindrical vector vortex (CVV) beam, which possesses both helical phase front and spatially inhomogeneous polarization, is a promising structured light for its various applications ranging from optical communication to optical field manipulation and optical microscopy. However, approaches to generate CVV beams with switchable and tunable polarization order and topological charge are still immature, which hinders the wide application of CVV beams. In this paper, we have experimentally demonstrated that order-controllable CVV beams can be produced by using spatial light modulator (SLM) and equivalent q-plate system at wavelength of 1550.8 nm. It is shown that the topological charge of the CVV beam can be switched by directly programming the SLM. We have also demonstrated that the polarization order of the CVV beam can be tuned to as high as eight by employing an equivalent q -plate system, which consists of two cascaded metasurfaces and a half-wave plate. To further verify the helical phase of the CVV beam, we have proposed a novel measurement method based on first removing the vector property and then interfering the remaining helical phase with plane wave or spherical wave. Autors: Yanliang He;Huapeng Ye;Junmin Liu;Zhiqiang Xie;Xiaoke Zhang;Yuanjiang Xiang;Shuqing Chen;Ying Li;Dianyuan Fan; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 10 Publisher: IEEE
» Origami-Like 3-D Folded MEMS Approach for Miniature Inertial Measurement Unit
 Abstract:This paper presents a miniature 50 mm3 inertial measurement unit (IMU) implemented using a folded microelectromechanical systems (MEMS) process. The approach is based on wafer-level fabrication of high aspect-ratio single-axis sensors interconnected by flexible hinges and folded into a 3-D configuration, like a silicon Origami [1]. Two different materials for flexible hinges have been explored, including photo-definable polyimide and parylene-C. We report, for the first time, an IMU prototype with seven operational sensors: three accelerometers, three gyroscopes, and a prototype of a reference clock. This paper concludes with the results of experimental characterization of inertial sensors demonstrating the feasibility of the proposed approach for a compact IMU. [2016-0267] Autors: Alexandra Efimovskaya;Yu-Wei Lin;Andrei M. Shkel; Appeared in: Journal of Microelectromechanical Systems Publication date: Oct 2017, volume: 26, issue:5, pages: 1030 - 1039 Publisher: IEEE
» Our Hidden Figures {Point of View]
 Abstract:“Your mom made five palačinke (crêpe in Serbian), your brother ate two; how many are left for you?” For some reason, this “sweet” math got etched in my mind as one of my earliest memories. It was my dad, playing number games with me. And many others: card games, puzzles, word riddles, brainteasers, anything where you had to figure out things, he loved. Then of course, so did I. Autors: Jelena Kovačević; Appeared in: Proceedings of the IEEE Publication date: Oct 2017, volume: 105, issue:10, pages: 1847 - 1850 Publisher: IEEE
» Output Reachable Set Estimation for Switched Linear Systems and Its Application in Safety Verification
 Abstract:This paper addresses the output reachable set estimation problem for continuous-time switched linear systems consisting of Hurwtiz stable subsystems. Based on a common Lyapunov function approach, the output reachable set is estimated by a union of bounding ellipsoids. Then, multiple Lyapunov functions with time-scheduled structure are employed to estimate the output reachable set for switched systems under dwell-time constraint. Furthermore, the safety verification problem of uncertain switched systems is investigated based on the result of output reachable set estimation. First, a sufficient condition ensuring the existence of an approximate bisimulation relation between two switched linear systems with a prescribed precision is proposed. Then, the safety verification for an uncertain switched system can be performed through an alternative safety verification for a switched system with exact parameters. Numerical examples are provided to illustrate our results. Autors: Weiming Xiang;Hoang-Dung Tran;Taylor T. Johnson; Appeared in: IEEE Transactions on Automatic Control Publication date: Oct 2017, volume: 62, issue:10, pages: 5380 - 5387 Publisher: IEEE
» Outstanding Members and Chapters [Chapter News]
 Abstract:Presents information on IAS society Outstanding Chapter and Member awards. Autors: Peter Magyar; Appeared in: IEEE Industry Applications Magazine Publication date: Oct 2017, volume: 23, issue:5, pages: 72 - 74 Publisher: IEEE
» Overview of Environment Perception for Intelligent Vehicles
 Abstract:This paper presents a comprehensive literature review on environment perception for intelligent vehicles. The state-of-the-art algorithms and modeling methods for intelligent vehicles are given, with a summary of their pros and cons. A special attention is paid to methods for lane and road detection, traffic sign recognition, vehicle tracking, behavior analysis, and scene understanding. In addition, we provide information about datasets, common performance analysis, and perspectives on future research directions in this area. Autors: Hao Zhu;Ka-Veng Yuen;Lyudmila Mihaylova;Henry Leung; Appeared in: IEEE Transactions on Intelligent Transportation Systems Publication date: Oct 2017, volume: 18, issue:10, pages: 2584 - 2601 Publisher: IEEE
» Pairwise Force SPH Model for Real-Time Multi-Interaction Applications
 Abstract:In this paper, we present a novel pairwise-force smoothed particle hydrodynamics (PF-SPH) model to enable simulation of various interactions at interfaces in real time. Realistic capture of interactions at interfaces is a challenging problem for SPH-based simulations, especially for scenarios involving multiple interactions at different interfaces. Our PF-SPH model can readily handle multiple types of interactions simultaneously in a single simulation; its basis is to use a larger support radius than that used in standard SPH. We adopt a novel anisotropic filtering term to further improve the performance of interaction forces. The proposed model is stable; furthermore, it avoids the particle clustering problem which commonly occurs at the free surface. We show how our model can be used to capture various interactions. We also consider the close connection between droplets and bubbles, and show how to animate bubbles rising in liquid as well as bubbles in air. Our method is versatile, physically plausible and easy-to-implement. Examples are provided to demonstrate the capabilities and effectiveness of our approach. Autors: Tao Yang;Ralph R. Martin;Ming C. Lin;Jian Chang;Shi-Min Hu; Appeared in: IEEE Transactions on Visualization and Computer Graphics Publication date: Oct 2017, volume: 23, issue:10, pages: 2235 - 2247 Publisher: IEEE
» Parallel List Decoding of Convolutional Codes: Algorithm and Implementation
 Abstract:List decoding is a promising technique for machine type communications (MTC) and other applications that pursue the high-coding gain of convolutional codes. However, there are obstacles that degrade the availability of list decoding. In specific, non-tail-biting list decoding involves high demands of data storage, while tail-biting list decoding requires substantial computational resources to preserve the optimal performance. In this paper, we rethink the parallel list decoder design from the aspects of algorithm and implementation to circumvent the foregoing obstacles. On the one hand, internal relations among the multiple decoding sequences are revealed and leveraged to redesign the non-tail-biting list decoding algorithm, which enables the design to extricate from the massive storage expense. On the other hand, a reliability-ordered initial-state estimator is designed for the tail-biting list decoder, which helps to alleviate the computational burden while retaining the optimal error-correction performance. In conjunction with the optimizations on underlying structures, the proposed list decoder achieves better energy efficiency than existing work under the same coding gain. In the MTC scenario, moreover, the proposed design will be less area consuming than existing schemes to fulfill coding gain enhancement. Autors: Jian Wang;Matthias Korb;Kangli Zhang;Harald Kröll;Qiuting Huang;Jibo Wei; Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers Publication date: Oct 2017, volume: 64, issue:10, pages: 2806 - 2817 Publisher: IEEE
» Parallel Multiclass Support Vector Machine for Remote Sensing Data Classification on Multicore and Many-Core Architectures
 Abstract:Support Vector Machine (SVM) is a classification method that has been widely used in the domain of remote sensing for decades. Although SVM-based classification method achieves good performance for classification accuracy in many studies, it can become very time-consuming in some remote sensing applications such as hyperspectral image classification or large-scale land cover mapping. To improve the efficiency for SVM training and classification in remote sensing applications, we designed and implemented a highly efficient multiclass support vector machine (MMSVM) for × 86-based multicore and many-core architectures such as the Ivy Bridge CPUs and the Intel Xeon Phi coprocessor (MIC) based on our previous MIC-SVM library. Various analysis methods and optimization strategies are employed to fully utilize the multilevel parallelism of our studied architectures. We select several real-world remote sensing datasets to evaluate the performance of our proposed MMSVM. Compared with the widely used serial LIBSVM, our MMSVM achieves 6.3–31.1 (in training) and 4.9–32.2 (in classification) speedups on MIC, and 6.9–14.9 (in training) and 5.5–22.1 (in classification) speedups on the Ivy Bridge CPUs. We also conduct a performance comparison analysis on different platforms and provide some ideas on how to select the most suitable architecture for specific remote sensing classification problems in order to achieve the best performance. Autors: Weijia Li;Haohuan Fu;Yang You;Le Yu;Jiarui Fang; Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Publication date: Oct 2017, volume: 10, issue:10, pages: 4387 - 4398 Publisher: IEEE
» Parallel Operation of Inverters With Isolated DC Link for Minimizing Sharing Inductor
 Abstract:In this paper, it is described how the circulating current flows between inverters that have isolated dc link such as cascaded H-bridge (CHB) topology when they are operating in parallel. In this case, zero sequence circulating current, which normally flows through shared dc link, cannot flow between inverters in parallel. However, circulating current is provoked by asynchronous switching instant of devices, difference of dc-link voltages of parallel inverters, and unbalanced impedance. The circulating current should be suppressed by a sharing inductor that is inserted between inverters. Generally, all of the inverters should synthesize the same output voltage reference for load current control to minimize the size of this sharing reactor. However, this conventional method cannot guarantee diminishing circulating current in the transient state and even in the steady state. In this paper, in order to reduce sharing reactance, after deriving circulating current model from general case of n-parallel operation, circulating current control method is devised based on the model. This proposed algorithm is applied to active front end five-level-CHB inverter system for medium voltage drive. Simulation and experimental results are provided to verify the effectiveness of the proposed control scheme. Autors: Hyun-Sam Jung;Jeong-Mock Yoo;Seung-Ki Sul;Hak-Jun Lee;Chanook Hong; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4450 - 4459 Publisher: IEEE
» Parallel Resonance Detection and Selective Compensation Control for SAPF With Square-Wave Current Active Injection
 Abstract:Due to capacitor elements and inductive line impedance in power system, parallel resonance could be triggered in the presence of harmonic currents from nonlinear load, whose frequency may shift resulting from intermittent switching of the capacitor devices. So it is difficult for shunt active power filter (SAPF) to damp parallel resonance. This paper investigates parallel resonance detection with square-wave current active injection and selective compensation control with closed-loop regulation of point of common coupling (PCC) voltage for SAPF. The principles of parallel resonance and its frequency detection are analyzed by means of equivalent circuit. Through injecting given square-wave current lasting for 0.5 s, SAPF could fast detect parallel resonance with the help of spectrum analysis of resonance power index. In order to improve power quality of both PCC voltage and grid current, SAPF is controlled to suppress specified harmonic currents from nonlinear load and selectively damp parallel resonance at the same time. In addition, ordinary proportional-integral plus advanced repetitive controller in parallel is used to improve current tracking performance. Experiment test results are provided to verify the validity of proposed detection and control methods. Autors: Chen Xu;Ke Dai;Xinwen Chen;Li Peng;Yuxiao Zhang;Ziwei Dai; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8066 - 8078 Publisher: IEEE
» Parameter Estimation via Unlabeled Sensing Using Distributed Sensors
 Abstract:In this letter, the problem of estimating an unknown deterministic parameter is studied, where each sensor acquires a noisy version of the signal and the data at fusion center are unlabeled. Two scenarios are studied: one in which each sensor uses analog communication to transmit its observations with different channel coefficients, and the other in which each sensor uses a different threshold to quantize the noisy signal with a transition matrix describing the channel. Sufficient conditions are provided, under which maximum likelihood (ML) estimators can be found in polynomial time, and numerical simulations are conducted to evaluate performances of ML estimators. Autors: Jiang Zhu;Hangting Cao;Chunyi Song;Zhiwei Xu; Appeared in: IEEE Communications Letters Publication date: Oct 2017, volume: 21, issue:10, pages: 2130 - 2133 Publisher: IEEE
» Parametric Detection and Classification of Compact Conductivity Contrasts With Electrical Impedance Tomography
 Abstract:Electrical impedance tomography is a noninvasive and cost-effective imaging method that is increasingly attractive in the field of medical diagnostics. Several health conditions, such as stroke and solid tumors, are characterized by compact conductivity anomalies surrounded by a fairly regular background. Commonly employed voxel-by-voxel reconstruction methods for impedance imaging share the disadvantages of high computational cost and substantial sensitivity to measurement noise and imperfections in the electrical model describing the domain of interest. We present a special purpose algorithm for automatic detection and identification of compact conductivity variations. The technique exploits a priori structural information and, by reconstructing only the limited number of parameters required to describe a compact conductivity contrast, does not depend on a critical regularization parameter. The most demanding kernels are implemented to run on graphics processing units to accelerate computation. The parametric reconstruction is quicker and more robust than widely employed approaches with respect to measurement noise and imperfections in the electrical model, as shown by computational analysis performed on a segmented head domain and experimental measurements acquired on a cylindrical phantom. When the goal is quick detection of compact conductivity contrasts in complex 3-D domains, the inclusion of specific constraints relating to the problem considered leads to enhanced quality of reconstruction, making the presented technique a promising alternative to common voxel-by-voxel reconstruction methods. Autors: Andrea Samorè;Marco Guermandi;Silvio Placati;Roberto Guerrieri; Appeared in: IEEE Transactions on Instrumentation and Measurement Publication date: Oct 2017, volume: 66, issue:10, pages: 2666 - 2679 Publisher: IEEE
» Parasitic Inductance and Capacitance-Assisted Active Gate Driving Technique to Minimize Switching Loss of SiC MOSFET
 Abstract:High di/dt and dv/dt of SiC MOSFET cause a considerable amount of overshoot in device voltage and current during switching transients in the presence of inverter layout parasitic inductance and load parasitic capacitance. The excessive overshoots in device voltage and current cause failure of the device. Moreover, these uncontrolled overshoots increase the switching loss in the inverter. It is difficult to reduce parasitic inductance beyond a certain point. This paper proposes an active gate driving technique, which allows inverter to operate with moderate amount of layout parasitic inductance and load parasitic capacitance. The proposed technique dramatically reduces switching loss of the SiC MOSFET with the help of existing parasitic elements. The proposed switching loss reduction technique is termed as quasi zero switching. The developed active gate driver has been tested in a double pulse test setup and a 10 kW two-level voltage source inverter driving an induction motor. Autors: Parthasarathy Nayak;Kamalesh Hatua; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Oct 2017, volume: 64, issue:10, pages: 8288 - 8298 Publisher: IEEE
» Pareto Optimality for the Single-Stream Transmission in Multiuser Relay Networks
 Abstract:In this paper, we study Pareto optimality for multiuser relay networks. We adopt single-stream transmission and amplify-and-forward relays. First, with fixed relay processing matrices and transmit and receive beamforming vectors, we study Pareto optimality with respect to the power of the transmitters. Based on the signal-to-noise-plus-interference ratio (SINR) balancing analysis, we give a necessary and sufficient condition for a set of SINRs to be Pareto optimal. Second, we consider Pareto optimality with respect to the relay processing matrices, where the power of the transmitters and the transmit and receive beamforming vectors is fixed. Taking advantage of multi-objective optimization analysis, we present a necessary and sufficient condition for a set of SINRs to be Pareto optimal. We also give a necessary condition to check whether Pareto optimality is fulfilled. Finally, with fixed relay processing matrices, we study Pareto optimality with respect to the transmit and receive beamforming vectors. Simulations show that our proposed algorithms outperform the compared schemes. Autors: Ruixue Hu;Tat-Ming Lok; Appeared in: IEEE Transactions on Wireless Communications Publication date: Oct 2017, volume: 16, issue:10, pages: 6503 - 6513 Publisher: IEEE
» Passive Loop Filter Assistance for CTSDMs
 Abstract:This brief presents a power reduction technique for continuous time sigma–delta modulators (CTSDMs). The approach consists of two elements. First, a passive low-pass filter is added in front of the modulator’s loop filter to reduce the high frequency components in the loop. As a result, the slew rate requirements of the opamps can be greatly reduced which allows a significant power saving. Unfortunately, the insertion of this low-pass filter also changes the modulator’s loop gain, and hence affects the noise transfer functions (NTFs) and signal transfer functions (STFs), in an undesired way. Therefore, the second proposed element consists of inserting a compensation branch which is such that the original loop gain, NTF and STF are restored. Thanks to this, our power saving technique is completely transparent on the system level such that all established techniques and toolboxes for CTSDM design can still be used. The technique is especially suited for one-bit CTSDMs, where the amount of high-frequency components in the loop is excessive. To showcase the technique, a self-oscillating sigma–delta modulator (which is a dedicated type of one-bit CTSDM) was implemented in a 65-nm CMOS process. It achieves a peak signal to noise and distortion ratio of 63 dB over a 20-MHz bandwidth at a power consumption of 1.7 mW while occupying a very small chip area of only 0.009 mm2. Autors: Dries Vercaemer;Johan Raman;Pieter Rombouts; Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs Publication date: Oct 2017, volume: 64, issue:10, pages: 1157 - 1161 Publisher: IEEE
» Passive-Compensation-Based Stable RF Phase Dissemination for Multiaccess Trunk Fiber Link With Anti-GVD and Anti-Backscattering Function
 Abstract:We propose and demonstrate a scheme of stable radio frequency (RF) phase dissemination for multiaccess trunk fiber link by passive frequency mixing with anti-group velocity dispersion (GVD) and anti-backscattering function. The propagation delay of the entire fiber link is detected by a round-trip probe signal. After converting the frequency of the precompensated signal to the same frequency as the backward probe signal, the phase drifts can be eliminated automatically by frequency mixing at an arbitrary receiving node. Signals with different radio frequencies at the same wavelength are employed in the forward and backward transmissions to efficiently suppress the effect of the GVD and Rayleigh backscattering at the same time. In the experiment, a 2.4-GHz RF signal is delivered through a 50.2-km single mode fiber with autophase correction. The residual phase jitter of the recovered signals is no more than 0.031 rd at two points along the trunk fiber link. Autors: Yajie Cui;Tianwei Jiang;Song Yu;Ruihuan Wu;Wanyi Gu; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 8 Publisher: IEEE
» Passively Q-Switched Ho,Pr:LiLuF4 Laser at 2.95 μm Using MoSe2
 Abstract:In this letter, we report a diode-end-pumped continuous wave (CW) and passively Q-switched Ho,Pr:LLF laser at 2.95 μm. A maximum CW output power of 98 mW was achieved. The highest output power of 58 mW was radiated with a pulse duration of 818.8 ns and a repetition rate of 71.05 kHz. Even shorter pulse duration of 731.5 ns was obtained at a minor output coupler transmission. Autors: Zhengyu Yan;Guoqiang Li;Tao Li;Shengzhi Zhao;Kejian Yang;Shuaiyi Zhang;Mingqi Fan;Lei Guo;Baitao Zhang; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 7 Publisher: IEEE
» Pathway Analysis with Signaling Hypergraphs
 Abstract:Signaling pathways play an important role in the cell’s response to its environment. Signaling pathways are often represented as directed graphs, which are not adequate for modeling reactions such as complex assembly and dissociation, combinatorial regulation, and protein activation/inactivation. More accurate representations such as directed hypergraphs remain underutilized. In this paper, we present an extension of a directed hypergraph that we call a signaling hypergraph. We formulate a problem that asks what proteins and interactions must be involved in order to stimulate a specific response downstream of a signaling pathway. We relate this problem to computing the shortest acyclic -hyperpath in a signaling hypergraph—an NP-hard problem—and present a mixed integer linear program to solve it. We demonstrate that the shortest hyperpaths computed in signaling hypergraphs are far more informative than shortest paths, Steiner trees, and subnetworks containing many short paths found in corresponding graph representations. Our results illustrate the potential of signaling hypergraphs as an improved representation of signaling pathways and motivate the development of novel hypergraph algorithms. Autors: Anna Ritz;Brendan Avent;T. M. Murali; Appeared in: IEEE/ACM Transactions on Computational Biology and Bioinformatics Publication date: Oct 2017, volume: 14, issue:5, pages: 1042 - 1055 Publisher: IEEE
» PBTI in HKMG nMOS Transistors— Effect of Width, Layout, and Other Technological Parameters
 Abstract:This paper discusses in detail the effects of transistor width, layout, and technological parameters like gate dielectric and Lanthanum capping layer thickness on positive bias temperature instability (PBTI) of nMOS transistors fabricated using 28-nm gate-first High- metal gate CMOS technology. It is shown that the PBTI reduces with decrease in width (), increase in capping layer thickness and decrease in high- dielectric thickness. The physical mechanisms responsible for these dependencies are investigated and attributed to the modulation of preexisting traps in the high- dielectric and the modulation of electron injection into these traps. It is also shown that the PBTI of the devices could be improved by dividing a single active into multiple actives, by increasing active-to-active spacing and gate pitch. Autors: Pardeep Duhan;V. Ramgopal Rao;Nihar Ranjan Mohapatra; Appeared in: IEEE Transactions on Electron Devices Publication date: Oct 2017, volume: 64, issue:10, pages: 4018 - 4024 Publisher: IEEE
» Pea-Sized mmW Transceivers: QFN-?Based Packaging Concepts for Millimeter-Wave Transceivers
 Abstract:Enormous technological progress accomplished over the last several decades has facilitated the use of millimeter-wave (mmW) frequencies for mass-produced products such as automotive radars, industrial sensors, highspeed data communication links, and medical devices. The main enablers are new semiconductor technologies, with constantly improving cut-off frequencies reaching several hundred gigahertz. However, the dominant limiting factor for the mass production of low-cost mmW systems above 100 GHz is that suitable packaging technologies are not yet available. Still, a dramatic increase in research and development is taking place in the area of mmW packaging. The goal of this article is to provide a short overview of the topic and then present one particular approach in detail: the idea of integrating a complete mmW front end, including the antenna, into one small solderable surface mount device (SMD). Autors: Thomas Zwick;Florian Boes;Benjamin Göttel;Akanksha Bhutani;Mario Pauli; Appeared in: IEEE Microwave Magazine Publication date: Oct 2017, volume: 18, issue:6, pages: 79 - 89 Publisher: IEEE
» Perceptually Driven Nonuniform Asymmetric Coding of Stereoscopic 3D Video
 Abstract:Asymmetric stereoscopic video coding has already proven its effectiveness in reducing the bandwidth required for stereoscopic 3D delivery without degrading the visual quality. This approach, in which the left and right views are encoded with different levels of quality, relies on the perceptual theory of binocular suppression. However, to ensure comfortable 3D viewing, the just-noticeable level of asymmetry, i.e., the maximum quality gap between views, has to be carefully defined. Both subjectively and empirically fixed thresholds of asymmetry demonstrated either the maladjustment to content or dependency to the experimental design. This paper describes a new nonuniform asymmetric stereoscopic video coding method adaptively adjusting the level of asymmetry for each region of the image based on its perceptual significance. The proposed method uses a fully automated model that dynamically determines the best bounds of asymmetry for which the 3D viewing experience will not be altered. This is achieved by exploiting several human-visual-system-inspired models, namely, the binocular just-noticeable difference, and the visual saliency map and depth information. The simulation results show that the proposed method results in bit rate saving of up to 26% and provides better 3D visual quality compared with state-of-the-art asymmetric coding methods. Autors: Sid Ahmed Fezza;Mohamed-Chaker Larabi; Appeared in: IEEE Transactions on Circuits and Systems for Video Technology Publication date: Oct 2017, volume: 27, issue:10, pages: 2231 - 2245 Publisher: IEEE
» Performance Analysis and Optimization in Downlink NOMA Systems With Cooperative Full-Duplex Relaying
 Abstract:We study a downlink non-orthogonal multiple access system with cooperative full-duplex relaying, where the near user in terms of the base station (BS) is enabled to act as a full-duplex relay for the far user. In particular, we first derive the outage probability and ergodic sum rate with closed-form expressions when the power allocations at the BS and relay (or the near user) are fixed. Then, we analytically obtain the optimal power allocations with closed-form expressions at the BS and relay to minimize the outage probability. Furthermore, by taking the fairness between the near user and far user into account, we characterize the optimal power allocations with closed-form expressions at the BS and relay to maximize the minimum achievable rate of users. Simulation results validate the correctness of the theoretical analysis and demonstrate the advantages of the proposed algorithms over the state of the art. Autors: Lin Zhang;Jiaqi Liu;Ming Xiao;Gang Wu;Ying-Chang Liang;Shaoqian Li; Appeared in: IEEE Journal on Selected Areas in Communications Publication date: Oct 2017, volume: 35, issue:10, pages: 2398 - 2412 Publisher: IEEE
» Performance Analysis of Overlay Spectrum Sharing in Hybrid Satellite-Terrestrial Systems With Secondary Network Selection
 Abstract:In this paper, we study a hybrid satellite-terrestrial spectrum sharing system (HSTSSS) in which multiple terrestrial secondary networks cooperate with a primary satellite network for dynamic spectrum access. For complexity-aware HSTSSS design, we propose an amplify-and-forward-based overlay spectrum sharing protocol using partial and opportunistic secondary network selection schemes. The secondary network selection aims to minimize the outage probability of the primary satellite system and, thereby, to explore spectrum sharing opportunities. With the overlay approach, the selected secondary network allocates part of its power to relay the satellite signal and utilizes the remaining power to transmit its own signal. Considering Shadowed-Rician fading for satellite links, and Nakagami- as well as Rician fading for terrestrial links, we derive closed-form expressions for the outage probability of both primary and secondary networks, and examine their achievable diversity orders. Numerical and simulation results validate our analysis and highlight the performance gains of the proposed schemes for an HSTSSS with and without a direct satellite primary communication link. Autors: Pankaj K. Sharma;Prabhat K. Upadhyay;Daniel Benevides da Costa;Petros S. Bithas;Athanasios G. Kanatas; Appeared in: IEEE Transactions on Wireless Communications Publication date: Oct 2017, volume: 16, issue:10, pages: 6586 - 6601 Publisher: IEEE
» Performance Analysis of RSS Fingerprinting Based Indoor Localization
 Abstract:Indoor localization has been an active research field for decades, where received signal strength (RSS) fingerprinting based methodology is widely adopted and induces many important localization techniques, such as the recently proposed one building fingerprints database with crowdsourcing. While efforts have been dedicated to improve accuracy and efficiency of localization, performance of the RSS fingerprinting based methodology itself is still unknown in a theoretical perspective. In this paper, we present a general probabilistic model to shed light on a fundamental issue: how good the RSS fingerprinting based indoor localization can achieve? Concretely, we present the probability that a user can be localized in a region with certain size. We reveal the interaction among accuracy, reliability, and the number of measurements in the localization process. Moreover, we present the optimal fingerprints reporting strategy that can achieve the best localization accuracy with given reliability and the number of measurements, which provides a design guideline for the RSS fingerprinting based indoor localization system. Further, we analyze the influence of imperfect database information on the reliability of localization, and find that the impact of imperfect information is still under control with reasonable number of samplings when building the database. Autors: Xiaohua Tian;Ruofei Shen;Duowen Liu;Yutian Wen;Xinbing Wang; Appeared in: IEEE Transactions on Mobile Computing Publication date: Oct 2017, volume: 16, issue:10, pages: 2847 - 2861 Publisher: IEEE
» Performance Analysis of Single-Photon Avalanche Diode Underwater VLC System Using ARQ
 Abstract:Single-photon avalanche diode (SPAD) has recently been introduced as a powerful detector for long-distance underwater visible light communication (UVLC). In this paper, the performance of the SPAD detector in UVLC is analyzed considering the effect of the turbulence-induced fading resulting from air bubbles in addition to the combined effect of attenuation and scattering. An automatic repeat request (ARQ) system is adopted to mitigate different underwater impairments and reduce the error probability at the receiver side. Approximate packet error rate (PER) expressions are derived using Laguerre Gauss polynomial for a finite number of transmission. Next, the average energy efficiency and throughput are analyzed to account for the increased energy consumption cost and the decreased effective transmission rate, which results from adopting the ARQ scheme. Finally, different numerical results are introduced to verify the derived PER expressions, demonstrate the ability of the proposed ARQ system in extending the transmission range, and show the tradeoff between energy efficiency and throughput. Autors: Taniya Shafique;Osama Amin;Mohamed Abdallah;Imran Shafique Ansari;Mohamed-Slim Alouini;Khalid Qaraqe; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 11 Publisher: IEEE
» Performance and Reliability Codesign for Superjunction Drain Extended MOS Devices
 Abstract:Conventionally, integrated drain-extended MOS (DeMOS) like high-voltage devices are designed while keeping only performance targets for a given application in mind. In this paper, for the first time, performance and reliability codesign approach using 3-D TCAD has been presented for various superjunction (SJ) type DeMOS devices. In this context, how to effectively utilize the SJ concept in a DeMOS device for System on Chip applications, which often has stringent switching and RF performance targets, is explored in detail in this paper. Moreover, design and reliability tradeoffs for switching and RF applications are discussed, while considering two unique sets, one with fixed breakdown voltage and other with fixed ON-resistance. Finally, hot carrier generation, safe operating area concerns, and electrostatic discharge physics are explored and compared using 3-D TCAD simulations. Autors: Jhnanesh Somayaji;B. Sampath Kumar;M. S. Bhat;Mayank Shrivastava; Appeared in: IEEE Transactions on Electron Devices Publication date: Oct 2017, volume: 64, issue:10, pages: 4175 - 4183 Publisher: IEEE
» Performance Assessment of a Custom, Portable, and Low-Cost Brain–Computer Interface Platform
 Abstract:Objective: Conventional brain-computer interfaces (BCIs) are often expensive, complex to operate, and lack portability, which confines their use to laboratory settings. Portable, inexpensive BCIs can mitigate these problems, but it remains unclear whether their low-cost design compromises their performance. Therefore, we developed a portable, low-cost BCI and compared its performance to that of a conventional BCI. Methods: The BCI was assembled by integrating a custom electroencephalogram (EEG) amplifier with an open-source microcontroller and a touchscreen. The function of the amplifier was first validated against a commercial bioamplifier, followed by a head-to-head comparison between the custom BCI (using four EEG channels) and a conventional 32-channel BCI. Specifically, five able-bodied subjects were cued to alternate between hand opening/closing and remaining motionless while the BCI decoded their movement state in real time and provided visual feedback through a light emitting diode. Subjects repeated the above task for a total of 10 trials, and were unaware of which system was being used. The performance in each trial was defined as the temporal correlation between the cues and the decoded states. Results: The EEG data simultaneously acquired with the custom and commercial amplifiers were visually similar and highly correlated ( = 0.79). The decoding performances of the custom and conventional BCIs averaged across trials and subjects were 0.70 0.12 and 0.68 0.10, respectively, and were not significantly different. Conclusion: The performance of our portable, low-cost BCI is comparable to that of the conventional BCIs. Significance: Platforms,- such as the one developed here, are suitable for BCI applications outside of a laboratory. Autors: Colin M. McCrimmon;Jonathan Lee Fu;Ming Wang;Lucas Silva Lopes;Po T. Wang;Alireza Karimi-Bidhendi;Charles Y. Liu;Payam Heydari;Zoran Nenadic;An Hong Do; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Oct 2017, volume: 64, issue:10, pages: 2313 - 2320 Publisher: IEEE
» Performance Characterization on Handling Large-Scale Partitionable Workloads on Heterogeneous Networked Compute Platforms
 Abstract:Multi-installment scheduling (MIS) has shown great effectiveness in minimizing the processing time for large-scale partitionable workloads. To derive an optimal MIS strategy, one has to explicitly determine optimal numbers of installments and processors. Existing studies tend to solve this problem by treating the influence of number of installments (and processors) w.r.t processing time as time-continuous functions and taking the derivative of these functions to determine the optimal values, which may lead to invalid solutions. In this paper, we employ periodic multi-installment scheduling (P-MIS) models for homogeneous and heterogeneous single-level tree networks. Using these models we make the following significant contributions. First, we derive a closed-form solution for an optimal number of installments based on a given network size and a fixed load distribution sequence. Second, we propose a heuristic algorithm for determining an optimal number of processors by first proving several important intermediate lemmas and theorems. Third, for heterogeneous systems, we propose a genetic algorithm to determine an optimal load distribution sequence. Finally, we conduct various experiments to illustrate the effectiveness of the proposed algorithms and perform rigorous analysis on the influence of load distribution sequence on processing time, on the basis of which a practical advice for determining a near-optimal load distribution sequence is given. Autors: Xiaoli Wang;Bharadwaj Veeravalli; Appeared in: IEEE Transactions on Parallel and Distributed Systems Publication date: Oct 2017, volume: 28, issue:10, pages: 2925 - 2938 Publisher: IEEE
» Performance Comparison of a Freeform Lens and a CDTIRO When Combined With an LED
 Abstract:This paper compares the features and performance of two secondary optics when combined with an LED. The aim and application of the secondary optic are explained in the introduction section. Sections 2 and 3 introduce two optics: A freeform lens and a novel circular dielectric totally internally reflecting optic (CDTIRO), which can provide uniform illumination. The design process, ray tracing simulations and experimental performance of the freeform lens are described in detail in Section 2. The ray tracing simulation and experimental performance of the CDTIRO are presented in Section 3. Section 4 presents a comparison of the features of both lenses and their performance. Both optics can produce over 95% uniformity within an illuminated area. However, the uniformity produced by the freeform lens reduces abruptly compared with the CDTIRO when some parameters such as size and the position of the light source are changed. Autors: Sina Babadi;Roberto Ramirez-Iniguez;Tuleen Boutaleb;Tapas Mallick; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 8 Publisher: IEEE
» Performance Evaluation and Parametric Optimum Choice Criteria of a Near-Field Thermophotovoltaic Cell
 Abstract:Based on the near-field (NF) model of a thermophotovoltaic cell (TPVC) consisting of an emitter and a photovoltaic (PV) cell separated by a vacuum gap, two important formulas for the power output and efficiency are analytically derived by using fluctuation electrodynamics theory. The general performance characteristics of the NF-TPVC are evaluated. The optimum choice criteria of several key parameters, such as the power output density, efficiency, and distance of the vacuum gap of the TPVC, the current density and voltage output of the PV cell, and the band-gap of semiconductor materials in the PV cell, are supplied. Moreover, the maximum power output densities and efficiencies of three NF-TPVCs made of InSb, InAs, and InGaAsSb are calculated and the corresponding optimum values of other parameters are determined. The results obtained may provide some theoretical guidance for engineers to optimally design NF-TPVCs. Autors: Tianjun Liao;Zhimin Yang;Qingchun Dong;Xiaohang Chen;Jincan Chen; Appeared in: IEEE Transactions on Electron Devices Publication date: Oct 2017, volume: 64, issue:10, pages: 4144 - 4148 Publisher: IEEE
» Performance Investigation of Underwater Wireless Optical Communication System Using M -ary OAMSK Modulation Over Oceanic Turbulence
 Abstract:The performance of M-ary orbital angular momentum-shift keying (OAMSK) modulation-based underwater wireless optical communication (UWOC) system is investigated over oceanic turbulence with Laguerre–Gauss beam considered. On the basis of Rytov approximation, the detection probability and power distribution among the received signals are derived. The conditional probability and symbol error rate (SER) are, then, achieved by the maximum likelihood estimation. With Blahut–Arimoto algorithm, the channel capacity for this UWOC system is obtained. The results show that the optimal transmitted OAM mode set S is mainly restricted by the interfering energy and decaying effective energy. With the optimal mode interval achieved, the SER performances for different modulation orders M and the minimum required transmitting power to reach the SER of 10−9 are sensitive to the variation in oceanic turbulence conditions. Additionally, the value of capacity will shift to a higher value with the increasing M, and a suitable M should be selected to balance the transmitting power consumption and capacity gain. This work is beneficial to M-ary OAMSK modulation-based UWOC system design. Autors: Wei Wang;Ping Wang;Tian Cao;Hongxin Tian;Yan Zhang;Lixin Guo; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 15 Publisher: IEEE
» Performance of Dynamic and Static TDD in Self-Backhauled Millimeter Wave Cellular Networks
 Abstract:Initial deployments of millimeter wave (mm-wave) cellular networks are likely to be enabled with self-backhauling. In this paper, we propose a random spatial model to analyze uplink (UL) and downlink (DL) signal to interference plus noise ratio distribution and mean rates corresponding to different access-backhaul and UL–DL resource allocation schemes in a self-backhauled mm-wave cellular network with Poisson point process (PPP) deployment of users and base stations (BSs). In particular, we focus on heuristic implementations of static and dynamic time division duplexing (TDD) for access links with synchronized or unsynchronized access-backhaul (SAB or UAB) time splits. We propose PPP approximations to characterize the distribution of the new types of interference encountered with dynamic TDD and UAB. These schemes offer better resource utilization than static TDD and SAB, however, potentially higher interference makes their choice non-trivial and the offered gains sensitive to different network parameters, including UL/DL traffic asymmetry, user load per BS or number of slave BSs per master BS. One can harness notable gains from UAB and/or dynamic TDD only if backhaul links are designed to have much larger throughput than the access links. Autors: Mandar N. Kulkarni;Jeffrey G. Andrews;Amitava Ghosh; Appeared in: IEEE Transactions on Wireless Communications Publication date: Oct 2017, volume: 16, issue:10, pages: 6460 - 6478 Publisher: IEEE
» Period-Doubling and Quadrupling Bifurcation of Vector Soliton Bunches in a Graphene Mode Locked Fiber Laser
 Abstract:Period-doubling bifurcation and period-quadrupling bifurcation of vector soliton pulses in a graphene mode locked fiber laser is experimentally observed and investigated. Not only single vector soliton but also vector soliton bunches as a unity are found to exhibit period-doubling and period-quadrupling bifurcation. The experimental results suggest that period-doubling and quadrupling bifurcation are intrinsic features of the pulses circulating in a nonlinear ring cavity, which are independent of the properties of the mode-locker in the fiber lasers. Autors: Yufeng Song;Zhiming Liang;Han Zhang;Qian Zhang;Luming Zhao;Deyuan Shen;Dingyuan Tang; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 8 Publisher: IEEE
» Permanent Magnet Temperature Estimation in PM Synchronous Motors Using Low-Cost Hall Effect Sensors
 Abstract:Knowledge of the permanent magnet (PM) temperature in PM synchronous machines (PMSMs) is of great importance both for control and monitoring purposes. Increase in PM temperature during motor operation can degrade the magnetic flux strength and consequently the machine's torque production capability, and can also cause irreversible demagnetization of the PM. Direct measurement of the PM temperature is not viable in practice due to both cost and reliability issues. Indirect PM temperature estimation methods recently studied require knowledge of thermal or electrical model parameters or can have undesired effects on motor operation. In this paper, the feasibility of using low-cost Hall-effect sensors for PM temperature estimation is investigated. Hall sensors are present for detecting the initial position of the rotor in majority of PMSM applications for which incremental encoders are used for control. The proposed method can, therefore, be implemented with low or no additional cost. Experimental results on two interior PMSMs show that the method is capable of providing noninvasive estimation of the PM temperature without a priori motor parameter information for monitoring and protection against excessive increase in temperature. Autors: Daniel Fernandez;Doosoo Hyun;Yonghyun Park;David Díaz Reigosa;Sang Bin Lee;Dong-Myung Lee;Fernando Briz; Appeared in: IEEE Transactions on Industry Applications Publication date: Oct 2017, volume: 53, issue:5, pages: 4515 - 4525 Publisher: IEEE
» Petroleum Refinery Mesh Network Propagation Measurements
 Abstract:This communication presents the results of the first field measurement campaign to characterize the large- and small-scale propagation statistics of the peer-to-peer wireless link in an operating petroleum refinery. Results for ground level transmission and transmission between ground level and devices mounted 18 m from the ground on a distillation stack are included. The measurements characterize the 20-MHz multiple-input, single-output channel at 2.45 GHz. Analysis of the measurement data reveals an environment with severe small-scale fading and multipath dispersion but very mild large-scale signal attenuation given the level of obstruction on the links. Autors: Geoffrey G. Messier;Michael W. Wasson;Michael J. Herrmann; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5645 - 5648 Publisher: IEEE
» Phase Noise Compensation for Nonlinearity-Tolerant Digital Subcarrier Systems With High-Order QAM
 Abstract:The fundamental penalty of subcarrier modulation (SCM) with independent subcarrier phase noise processing is estimated. It is shown that the fundamental signal-to-noise ratio (SNR) penalty related to poorer phase noise tolerance of decreased baudrate subcarriers increases significantly with modulation format size and can potentially exceed the gains of the nonlinear tolerance of SCM. A low-complexity algorithm is proposed for joint subcarrier phase noise processing, which is scalable in the number of subcarriers and recovers almost entirely the fundamental SNR penalty with respect to single-carrier systems operating at the same net data-rate. The proposed algorithm enables high-order modulation formats with high count of subcarriers to be safely employed for nonlinearity mitigation in optical communication systems. Autors: M. P. Yankov;L. Barletta;D. Zibar; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 12 Publisher: IEEE
» Phase Partition and Online Monitoring for Batch Process Based on Multiway BEAM
 Abstract:Batch process can exhibit significantly different characteristics across different phases, hence it is significant to partition it reasonably and set up corresponding subphase models for online monitoring. Unlike traditional phase-partition algorithms that customarily exploit the result of PCA algorithm for advanced research, an innovative algorithm which directly extracts effective information from the covariance matrix is presented in this paper, which is called multiway beacon exception analysis for maintenance (MBEAM). Its theoretics and statistical characteristics are demonstrated adequately. Based on the accurate capture of the change in variable correlation caused by characteristic variance of the process, the algorithm can separate the process into major phases and transition patterns automatically. The time-varying characteristics will then remain relatively stable in each independent subphase and will be supervised by homologous monitoring model that reflects the inherent phase feature. Due to its simple and intuitive format, MBEAM has superior performance in computation efficiency and fault interpretation, which is illuminated later in this paper. Synthetical illustrations are given concerning the influences of major parameters on the monitoring performance. Comparison with the step-wise sequential phase partition algorithm is conducted for a clearer insight. Experiments are carried out to further confirm the validation of the proposed method. Autors: Runxia Guo;Kai Guo;Jiankang Dong; Appeared in: IEEE Transactions on Automation Science and Engineering Publication date: Oct 2017, volume: 14, issue:4, pages: 1582 - 1589 Publisher: IEEE
» Phase Retrieval Approach for DOA Estimation With Array Errors
 Abstract:Direction-of-arrival estimation in the presence of gain and phase errors is investigated from the phase retrieval (PR) perspective. In order to remove the influence of phase errors, they are isolated by taking the absolute values of the elements in the compensated covariance matrix. Finally, the formulated nonconvex PR optimization problem is solved by utilizing the feasible point pursuit algorithm. Simulation results demonstrate the effectiveness of the proposed algorithm. Autors: Wenyi Wang;Renbiao Wu;Junli Liang;Hing Cheung So; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2610 - 2620 Publisher: IEEE
» Phase Vector Incompressible Registration Algorithm for Motion Estimation From Tagged Magnetic Resonance Images
 Abstract:Tagged magnetic resonance imaging has been used for decades to observe and quantify motion and strain of deforming tissue. It is challenging to obtain 3-D motion estimates due to a tradeoff between image slice density and acquisition time. Typically, interpolation methods are used either to combine 2-D motion extracted from sparse slice acquisitions into 3-D motion or to construct a dense volume from sparse acquisitions before image registration methods are applied. This paper proposes a new phase-based 3-D motion estimation technique that first computes harmonic phase volumes from interpolated tagged slices and then matches them using an image registration framework. The approach uses several concepts from diffeomorphic image registration with a key novelty that defines a symmetric similarity metric on harmonic phase volumes from multiple orientations. The material property of harmonic phase solves the aperture problem of optical flow and intensity-based methods and is robust to tag fading. A harmonic magnitude volume is used in enforcing incompressibility in the tissue regions. The estimated motion fields are dense, incompressible, diffeomorphic, and inverse-consistent at a 3-D voxel level. The method was evaluated using simulated phantoms, human brain data in mild head accelerations, human tongue data during speech, and an open cardiac data set. The method shows comparable accuracy to three existing methods while demonstrating low computation time and robustness to tag fading and noise. Autors: Fangxu Xing;Jonghye Woo;Arnold D. Gomez;Dzung L. Pham;Philip V. Bayly;Maureen Stone;Jerry L. Prince; Appeared in: IEEE Transactions on Medical Imaging Publication date: Oct 2017, volume: 36, issue:10, pages: 2116 - 2128 Publisher: IEEE
» Phased Array Imaging of Complex-Geometry Composite Components
 Abstract:Progress in computational fluid dynamics and the availability of new composite materials are driving major advances in the design of aerospace engine components which now have highly complex geometries optimized to maximize system performance. However, shape complexity poses significant challenges to traditional nondestructive evaluation methods whose sensitivity and selectivity rapidly decrease as surface curvature increases. In addition, new aerospace materials typically exhibit an intricate microstructure that further complicates the inspection. In this context, an attractive solution is offered by combining ultrasonic phased array (PA) technology with immersion testing. Here, the water column formed between the complex surface of the component and the flat face of a linear or matrix array probe ensures ideal acoustic coupling between the array and the component as the probe is continuously scanned to form a volumetric rendering of the part. While the immersion configuration is desirable for practical testing, the interpretation of the measured ultrasonic signals for image formation is complicated by reflection and refraction effects that occur at the water-component interface. To account for refraction, the geometry of the interface must first be reconstructed from the reflected signals and subsequently used to compute suitable delay laws to focus inside the component. These calculations are based on ray theory and can be computationally intensive. Moreover, strong reflections from the interface can lead to a thick dead zone beneath the surface of the component which limits sensitivity to shallow subsurface defects. This paper presents a general approach that combines advanced computing for rapid ray tracing in anisotropic media with a 256-channel parallel array architecture. The full-volume inspection of complex-shape components is enabled through the combination of both reflected and transmitted signals through the part using a pair of arrays held in a yoke c- nfiguration. Experimental results are provided for specimens of increasing complexity relevant to aerospace applications such as fan blades. It is shown that PA technology can provide a robust solution to detect a variety of defects including porosity and waviness in composite parts. Autors: Alex J. Brath;Francesco Simonetti; Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control Publication date: Oct 2017, volume: 64, issue:10, pages: 1573 - 1582 Publisher: IEEE
» Phaseless Near-Field Far-Field Transformation Utilizing Combinations of Probe Signals
 Abstract:Phaseless near-field far-field transformations based on nonconvex optimization suffer from local stationary points. In order to avoid the corresponding suboptimal solutions, the incorporation of combinations of probe signals into the cost functional is proposed and investigated. The nonconvex optimization based on the Wirtinger Calculus relies on forward and adjoint radiation operator evaluations via the fast irregular antenna field transformation algorithm (FIAFTA) and is performed by a memory-limited Quasi-Newton method. This allows the solution of large scale problems with utilization of the full flexibility of the FIAFTA in terms of measurement probe correction and arbitrary sample locations. Results for synthetic and measured near-field data reveal significant improvements when the knowledge of probe signal combinations is utilized, especially in applications with a large number of unknowns. Autors: Alexander Paulus;Josef Knapp;Thomas F. Eibert; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5492 - 5502 Publisher: IEEE

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