#### Electrical and Electronics Engineering publications abstract of: 10-2017 sorted by title, page: 16

» 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 Multicell Coordinated Beamforming for Downlink High-Speed Railway Communications
 Abstract:This paper investigates the multicell coordinated beamforming (MCBF) design for high-speed railway communications, where a high-mobility train goes through a multicell multiuser system in urban areas. All passengers in the train are aggregated to be a high-mobility “big user.” In order to explore the downlink system performance limit, we formulate an optimization problem to maximize the information rate from the serving base station to the high-mobility train while guaranteeing the minimal required achievable information rates of all low-mobility users outside the train by optimizing MCBF vectors. The interchannel interference (caused by Doppler effect to the train), the intercell interference and the interuser interference are jointly considered. Since the problem is nonconvex and cannot be solved directly, we first introduce an auxiliary variable (AV), and for a given AV, we find the optimal MCBF vectors via solving a second-order cone programming. Then, by updating the AV with the bisection method, the corresponding global optimal MCBF vectors are numerically obtained. Simulation results show that our proposed MCBF design greatly enhances the information throughput of the high-mobility train without degrading the required data rates of low-mobility users. Autors: Yang Lu;Ke Xiong;Pingyi Fan;Zhangdui Zhong; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Oct 2017, volume: 66, issue:10, pages: 9603 - 9608 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 Portable Electronically Controlled Needle-Free Jet Injection Systems
 Abstract:Jet injection is a process by which a fluid drug is delivered through the skin in the form of a high-velocity jet. Powering jet injection using a controllable actuator, such as a moving-coil permanent magnet motor, offers many advantages, but to date has required large and heavy injection systems to provide the required power and control bandwidth. In order to minimize the size of the injection system, we developed a scaling model for jet injection systems powered by permanent magnet motors, giving the optimal actuator mass as a function of jet velocity, injection volume, motor efficiency, and energy storage density. We combined this model with an existing electromagnetic model to confirm the predicted scaling relationships and find optimal actuator designs. On this basis, we designed an injection system for 50  volumes, including a compact power amplifier and control system, and verified its performance by performing injections into pig skin. The total mass of the injector system was 578 g, with a 178 g handpiece. This model illustrates fundamental relationships that govern the design of any jet-production device powered by linear electric motors for jet injection or other applications. Autors: Bryan P. Ruddy;Alex William Dixon;Rhys Michael James Williams;Andrew James Taberner; Appeared in: IEEE/ASME Transactions on Mechatronics Publication date: Oct 2017, volume: 22, issue:5, pages: 2013 - 2021 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 Error Probability for Weighted Collaborative Spectrum Sensing in Time- and Energy-Limited Cognitive Radio Networks
 Abstract:In this paper, a collaborative energy-harvesting cognitive radio (CR) network is considered such that the transmitter of the secondary user (SU) is allowed to harvest signal energy of the primary user (PU) when the presence of the PU is detected. The harvested energy is converted to electrical power in order to supply the sensing and transmission energy of SUs. The time frame (time slot) is divided into two phases allocated to sensing (divided into two durations: spectrum sensing and results reporting) and transmission, respectively. The time spanned by the results reporting duration depends on the number of collaborative sensing users, while the time spent on spectrum sensing duration controls the number of sensing samples. A constrained convex optimization problem of the overall probability of error is formulated incorporating constraints on time and energy resources along with PU interference protection presented as a threshold on probability of collision. We use a soft decision rule scheme while considering two energy harvesting scenarios namely, energy surplus and energy deficit. In each scenario, the convexity of the optimization problem is established analytically and the global optimal solution is obtained. Simulation results are provided to demonstrate the impact of the different parameters on the overall system performance as well as to verify the deduced analytical results. Autors: Abbas Taherpour;Hesameddin Mokhtarzadeh;Tamer Khattab; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Oct 2017, volume: 66, issue:10, pages: 9035 - 9049 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
» Optimizing Virtual Backup Allocation for Middleboxes
 Abstract:In enterprise networks, network functions, such as address translation, firewall, and deep packet inspection, are often implemented in middleboxes. Those can suffer from temporary unavailability due to misconfiguration or software and hardware malfunction. Traditionally, middlebox survivability is achieved by an expensive active-standby deployment where each middlebox has a backup instance, which is activated in case of a failure. Network function virtualization (NFV) is a novel networking paradigm allowing flexible, scalable and inexpensive implementation of network services. In this paper, we suggest a novel approach for planning and deploying backup schemes for network functions that guarantee high levels of survivability with significant reduction in resource consumption. In the suggested backup scheme, we take advantage of the flexibility and resource-sharing abilities of the NFV paradigm in order to maintain only a few backup servers, where each can serve one of multiple functions when corresponding middleboxes are unavailable. We describe different goals that network designers can consider when determining which functions to implement in each of the backup servers. We rely on a graph theoretical model to find properties of efficient assignments and to develop algorithms that can find them. Extensive experiments show, for example, that under realistic function failure probabilities, and reasonable capacity limitations, one can obtain 99.9% survival probability with half the number of servers, compared with standard techniques. Autors: Yossi Kanizo;Ori Rottenstreich;Itai Segall;Jose Yallouz; Appeared in: IEEE/ACM Transactions on Networking Publication date: Oct 2017, volume: 25, issue:5, pages: 2759 - 2772 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
» Ortholeg 2.0 ‑ Design of a Transparent Active Orthosis
 Abstract:In this work we propose a conceptual solution for performance limitation observed in many lower limb active orthosis. The concept is called transparent orthosis, and its objective is to improve the user walking experience to a more natural level, through the design of a lightweight and ergonomic mechanical structure, while using an autonomous and interactive software architecture. The details of transparency are shown through the design and development of a real transparent orthosis, called Ortholeg 2.0. Some aspects of the presented concept were tested in a previous developed device, the Ortholeg orthosis. Autors: Nicholas Bastos Melo;Carlos Eduardo Dorea;Pablo Javier Alsina;Marcio Valerio Araujo;Michael Gloger; Appeared in: IEEE Latin America Transactions Publication date: Oct 2017, volume: 15, issue:10, pages: 1869 - 1874 Publisher: IEEE
» OSNR aware composition of an open and disaggregated optical node and network
 Abstract:A function programmable optical network has been recently proposed to enhance the flexibility of an optical transport based on architecture-on-demand (AoD). The flexible synthesis of optical node architectures provided by AoD enables an open and disaggregated optical layer thanks to the available deep programmability. However, previous studies have focused on how to synthesize a single node out of switching function blocks, thus neglecting the optical signal-to-noise ratio (OSNR) impact, power imbalance effects due to the diverse set of devices traversed per input–output configuration, and networkwide implications. In this work, we present an optical network-wide function synthesis (ONetFuS), which is an algorithm to compose AoD nodes that consider placement and configuration of both switches and amplifiers. ONeFuS minimizes OSNR degradation and deviation across channels and offers enhanced power balance performance. Moreover, ONetFuS addresses multiple-node scenarios to investigate cascading, transmission distance, and networking effects. We compare the number of optical cross-connections computed by our proposal against solutions in the literature. Results in network scenarios, including the number of components, power balance, OSNR variations, and OSNR penalty reductions, prove the suitability of our proposed ONetFuS for open and functional programmable optical networks. Autors: Heng Liu;Adaranijo Peters;Miquel Garrich;Georgios Zervas; Appeared in: IEEE/OSA Journal of Optical Communications and Networking Publication date: Oct 2017, volume: 9, issue:10, pages: 844 - 854 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
» Outage and diversity analysis of underlay cognitive mixed RF-FSO cooperative systems
» 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
» PAM Decomposition of Ternary CPM With Duobinary Encoding
 Abstract:In this paper, we investigate the pulse amplitude modulation (PAM) decomposition and the spectral efficiency of duobinary continuous phase modulation (CPM), where duo- binary CPM represents a ternary CPM whose symbols are generated using a duobinary encoder. We show that this precoder ensures a higher spectral efficiency compared with binary CPM and we propose a PAM decomposition characterized by the presence of a single main pulse and by uncorrelated pseudo-symbols for a half integer modulation index value for this ternary CPM. We show that shaped offset quadrature phase shift keying belongs to this CPM family and we provide a new reduced complexity trellis detector capable of reaching identical performance as the one introduced by Perrins as well as new linear detectors. Autors: Rami Othman;Alexandre Skrzypczak;Yves Louët; Appeared in: IEEE Transactions on Communications Publication date: Oct 2017, volume: 65, issue:10, pages: 4274 - 4284 Publisher: IEEE
» PAPR Reduction for Hybrid ACO-OFDM Aided IM/DD Optical Wireless Vehicular Communications
 Abstract:Hybrid asymmetrically clipped optical orthogonal frequency division multiplexing (HACO-OFDM) improves the spectral efficiency compared to asymmetrically clipped optical OFDM (ACO-OFDM) and pulse-amplitude-modulated discrete multitone (PAM-DMT) modulation, while retaining the advantage of high power efficiency. HACO-OFDM has found favor in numerous applications, but its peak-to-average-power ratio (PAPR) has remained a concern in optical wireless communications, since the family of existing PAPR reduction methods cannot be directly invoked for the superimposed HACO-OFDM signals. Hence, we analyze the characteristics of HACO-OFDM signals and develop a specific PAPR reduction technique relying on tone injection. Our numerical results show that the proposed method achieves significantly improved PAPR statistics compared to the conventional methods, leading to a significant bit error ratio (BER) reduction. Autors: Baolong Li;Wei Xu;Hua Zhang;Chunming Zhao;Lajos Hanzo; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Oct 2017, volume: 66, issue:10, pages: 9561 - 9566 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
» Parameter Estimation-Based Time-Varying Sliding Mode Control for Multimotor Driving Servo Systems
 Abstract:This paper presents a parameter estimation-based time-varying sliding mode controller for the multimotor driving servo systems with the unknown parameters and actuator saturation, such that the finite-time coupling control of load output tracking and motors synchronization is achieved. First, the parameter estimation scheme employs the filtered representation of the load system dynamics to obtain the parameter estimation error, which is utilized to design the adaptive parameter law with dynamic gain to attain the finite-time parameter estimation with the prescribed transient and steady-state performances. Then, the generalized coupling error (GCE) is designed based on the estimation results to transform the complicated coupling control problem into the GCE convergence, which would extremely simplify the controller design. By incorporating the fuzzy echo state network (FESN), a time-varying sliding mode controller is presented to successfully eliminate the reaching phase and guarantee the finite-time GCE convergence with norm performance. For the FESN compensation, a novel learning law is derived based on the norm of FESN weight vector to reduce the computational cost where only a scalar weight needs to be updated online. Finally, the comparative experiments illustrate the benefits and reliability of the proposed algorithms. Autors: Wei Zhao;Xuemei Ren;Shubo Wang; Appeared in: IEEE/ASME Transactions on Mechatronics Publication date: Oct 2017, volume: 22, issue:5, pages: 2330 - 2341 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 Neutron Coincidence Counting With Plastic Scintillators for the Characterization of Radioactive Waste Drums
 Abstract:This paper reports a feasibility study, performed by numerical simulation with MCNPX-PoliMi v2.0, for plutonium quantitative assessment in radioactive waste packages by passive neutron coincidence counting with plastic scintillators. Owing to their low cost and good detection efficiency for fast neutrons, plastic scintillators could indeed constitute a good alternative to 3He proportional counters, which have become too costly because of 3He global shortage. However, their high-sensitivity to gamma rays and crosstalk are well-known drawbacks that need to be carefully studied. A measurement system for 118 L drums filled either with metallic or organic technological wastes have been modeled with MCNPX-PoliMi, and output data have been processed with ROOT. A 5-cm-thick lead shield is used in front of the detectors to attenuate plutonium and americium gamma radiation. In the studied cases, triple coincidences due to 240Pu spontaneous fissions represent more than 85% of the total signal when using crosstalk rejection algorithms, the 15% remaining coincidences being due to parasitic coincidences caused by () reactions or Am and Pu gamma rays. Although crosstalk rejection significantly reduces counting statistics, a few thousand triple coincidences are still recorded for 1 g of Pu homogeneously distributed in both metallic and organic matrices in a 25 min acquisition. For higher masses of Pu, a linear evolution of the number of coincidences with the mass is observed up to about 10 g. In addition, a study of Pu localization effects has shown that the triple coincidence difference is smaller than 20% between a point-like fission source and the homogeneous distribution in the drum. Autors: Benoît Simony;Bertrand Pérot;Cédric Carasco;Fanny Jallu;Nicolas Saurel;Sébastien Colas;Philippe Gironès;Johann Collot; Appeared in: IEEE Transactions on Nuclear Science Publication date: Oct 2017, volume: 64, issue:10, pages: 2719 - 2724 Publisher: IEEE
» Passive optical network based mobile backhaul enabling ultra-low latency for communications among base stations
 Abstract:Low latency is of key importance for mobile networks to support emerging time-critical applications, such as road traffic safety and efficiency. Meanwhile, a passive optical network (PON) is widely recognized as a promising solution for mobile backhaul networks thanks to its high capacity and low energy consumption. In the conventional PON-based mobile backhaul network, where base stations (BSs) are co-located with optical network units, the traffic between the neighboring BSs that are mainly caused by user mobility has to be first sent to the optical line terminal and even further, e.g., edge nodes of mobile core networks, resulting in high latency, although the adjacent BSs are geographically located close to each other. In this paper, a novel PON-based architecture is proposed for mobile backhaul to enhance the connectivity between neighboring BSs. Meanwhile, a tailored medium access control protocol and dynamic bandwidth allocation algorithm are introduced to support fast inter-BS communications. The results reveal that a low latency (less than 1 ms packet delay) for communications among any adjacent BSs can be achieved in the proposed PON-based mobile backhaul network, demonstrating great potential to support future time-critical applications. Autors: Jun Li;Jiajia Chen; Appeared in: IEEE/OSA Journal of Optical Communications and Networking Publication date: Oct 2017, volume: 9, issue:10, pages: 855 - 863 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 Downlink MU-TXOP Sharing in IEEE 802.11ac
 Abstract:The 802.11ac version of the popular IEEE 802.11 protocol aims to boost performance by increasing the channel bandwidth and allowing downlink multiuser multiple-input multiple-output (MIMO)—i.e., simultaneous transmission to multiple clients in the downlink direction. In this paper, we evaluate the performance improvements of multiuser Transmission Opportunity (MU-TXOP) sharing in this scenario under nonsaturated load and non-ideal channel condition, using a novel analytical model based on discrete Markov chain and E-limited M/G/1 queuing model. Our results show that MU-TXOP sharing achieves up to 105% gain in throughput compared to the case without MU-TXOP sharing. Moreover, the low-priority traffic benefits most from MU-TXOP sharing, with up to 150% throughput gain at low traffic intensity due to availability of additional transmission opportunities for secondary ACs. Autors: M. Zulfiker Ali;Jelena Mišić;Vojislav B. Mišić; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Oct 2017, volume: 66, issue:10, pages: 9365 - 9380 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 physical-layer security in an OCDMA-based wiretap channel
 Abstract:Based on information-theoretic security, physical-layer security in an optical code division multiple access (OCDMA) system is analyzed. For the first time, the security leakage factor is employed to evaluate the physicallayer security level, and the safe receiving distance is used to measure the security transmission range. By establishing the wiretap channel model of a coherent OCDMA system, the influences of the extraction location, the extraction ratio, the number of active users, and the length of the code on the physical-layer security are analyzed quantitatively. The physical-layer security and reliability of the coherent OCDMA system are evaluated under the premise of satisfying the legitimate user’s bit error rate and the security leakage factor. The simulation results show that the number of users must be in a certain interval in order to meet the legitimate user’s reliability and security. Furthermore, the security performance of the coherent OCDMA-based wiretap channel can be improved by increasing the code length. Autors: Jianhua Ji;Guirong Zhang;Wenjun Li;Lu Sun;Ke Wang;Ming Xu; Appeared in: IEEE/OSA Journal of Optical Communications and Networking Publication date: Oct 2017, volume: 9, issue:10, pages: 813 - 818 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 a Boron-Coated-Straw- Based HLNCC for International Safeguards Applications
 Abstract:3He gas has been used in various scientific and security applications for decades, but it is now in short supply. Alternatives to 3He detectors are currently being integrated and tested in neutron coincidence counter designs, of a type which are widely used in nuclear safeguards for nuclear materials assay. A boron-coated-straw-based design, similar to the High-Level Neutron Coincidence Counter-II, was built by Proportional Technologies Inc., and has been tested by the Oak Ridge National Laboratory (ORNL) at both the JRC in Ispra and ORNL. Characterization measurements, along with nondestructive assays of various plutonium samples, have been conducted to determine the performance of this coincidence counter replacement in comparison with other similar counters. This paper presents results of these measurements. Autors: Angela T. Simone;Stephen Croft;Robert D. McElroy;Liang Sun;Jeffrey L. Lacy;Athanasios Athanasiades;Jason P. Hayward; Appeared in: IEEE Transactions on Nuclear Science Publication date: Oct 2017, volume: 64, issue:10, pages: 2690 - 2697 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
» Performance of Secondary Network With Primary Beamforming-Assisted Energy Harvesting Transmitters
 Abstract:In this paper, we consider a novel energy-harvesting (EH) cognitive radio framework in which the primary source beamforms excess available energy to an EH secondary transmitter (ST) so as to enable it to share the spectrum. In the first phase of transmission, the multi-antenna primary source optimally beamforms symbols to its decode and forward relay while beamforming all excess energy to a selected EH ST. In the second phase while the relay transmits symbols to a selected primary receiver, the EH ST transmits symbols using underlay principles to its secondary receiver. Assuming peak interference constraints at the STs, we derive approximate expressions for outage probability and ergodic rate of the secondary link with the optimal beamformer. Using asymptotic expressions for outage and ergodic rate, we derive useful insights into performance of the system. We show that diversity equal to the number of secondary transmitters is achieved by the considered system. Computer simulations confirm accuracy of the derived expressions. Autors: Komal Janghel;Shankar Prakriya; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Oct 2017, volume: 66, issue:10, pages: 8895 - 8909 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
» Pervasive Monitoring of Motion and Muscle Activation: Inertial and Mechanomyography Fusion
 Abstract:Muscle activity and human motion are useful parameters to map the diagnosis, treatment, and rehabilitation of neurological and movement disorders. In laboratory and clinical environments, electromyography and motion capture systems enable the collection of accurate, high-resolution data on human movement and corresponding muscle activity. However, controlled surroundings limit both the length of time and the breadth of activities that can be measured. Features of movement, critical to understanding patient progress, can change during the course of a day and daily activities may not correlate to the limited motions examined in a laboratory. We introduce a system to measure motion and muscle activity simultaneously over the course of a day in an uncontrolled environment with minimal preparation time and ease of implementation that enables daily usage. Our system combines a bespoke inertial measurement unit (IMU) and mechanomyography sensor, which measures the mechanical signal of muscular activity. The IMU can collect data continuously, and transmit wirelessly, for up to 10 h. We describe the hardware design and validation, and outline the data analysis (including data processing and activity classification algorithms) for the sensing system. Furthermore, we present two pilot studies to demonstrate utility of the system, including activity identification in six able-bodied subjects with an accuracy of 98%, and monitoring motion/muscle changes in a subject with cerebral palsy and of a single leg amputee over extended periods (5 h). We believe these results provide a foundation for mapping human muscle activity and corresponding motion changes over time, providing a basis for a range of novel rehabilitation therapies. Autors: Richard B. Woodward;Sandra J. Shefelbine;Ravi Vaidyanathan; Appeared in: IEEE/ASME Transactions on Mechatronics Publication date: Oct 2017, volume: 22, issue:5, pages: 2022 - 2033 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
» Photocontrolled Terahertz Amplified Modulator via Plasma Wave Excitation in ORTD-Gated HEMTs
 Abstract:This paper theoretically explores photocontrolled terahertz amplified modulator in electron plasma wave optically switched resonant tunneling diode (ORTD) gate high-electron mobility transistor. We present a developed distributed circuit model based on the Khmyrova model. Photoexcitation causes ORTD operating state between negative differential conductivity and positive differential conductivity, which power gain of the device can be control by photoexcitation. Numerical and analytical results show that photoexcitation enabling amplified modulator can realize much larger modulation depth (>95%) than what has been reported in photocontrolled modulator. Our results show the potential of this device in several fields of terahertz technology, such as photocontrolled modulator, mixer, and other two port networks. Autors: Changju Zhu;Luhong Mao;Fan Zhao;Xurui Mao;Weilian Guo; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 8 Publisher: IEEE
» Photonic Crystal Lasers Fabricated by MOVPE Based on Organic Arsenic Source
 Abstract:We demonstrate the characteristics of photonic crystal lasers fabricated by air hole retained regrowth using metal-organic vapor-phase epitaxy based on an organic arsenic source [tertiary-butyl arsine (TBAs)]. TBAs has the advantage of high decomposition efficiency compared with AsH3, which enables us to achieve a unique air hole shape under the crystal regrowth. We demonstrate that photonic crystal lasers with an area of exhibit single-mode lasing with a low lasing threshold of ~0.5 kAcm−2. The effect of the unique shape of the air holes obtained by the TBAs-based regrowth on the laser performance is discussed using coupled-wave theory. Autors: M. De Zoysa;M. Yoshida;M. Kawasaki;K. Ishizaki;R. Hatsuda;Y. Tanaka;S. Noda; Appeared in: IEEE Photonics Technology Letters Publication date: Oct 2017, volume: 29, issue:20, pages: 1739 - 1742 Publisher: IEEE
» Photonic Crystal Surface Emitting Lasers With Quantum Dot Active Region
 Abstract:GaAs-based InAs/InGaAs/GaAs quantum dot (QD) photonic crystal (PC) surface emitting lasers of 1.3 μ m wavelength range are fabricated and room-temperature lasing emissions by optical pumping are demonstrated for the first time. Laser devices are characterized in terms of PC parameters and temperature-dependent measurements are also carried out. The impact of wavelength detuning between PC resonant wavelength and QD gain peak is manifested in the experiments. Moreover, simplified simulation reveals that etched PC depth plays an even more critical role in active region of QD compared to that of quantum well. Autors: Tzu-Shan Chen;Zong-Lin Li;Ming-Yang Hsu;Gray Lin;Sheng-Di Lin; Appeared in: Journal of Lightwave Technology Publication date: Oct 2017, volume: 35, issue:20, pages: 4547 - 4552 Publisher: IEEE
» Photonics enhanced sensors for food monitoring: Part 3
 Abstract:Food quality and food safety are gaining more and more importance in recent decades. In particular, applications have included domains such as the identification of foreign bodies in solid food streams, the quality screening of vegetables and fruits, the recognition of food products inducing a health risk and the monitoring of the quality and authentication of liquids. Solid food sensing methods are often insufficient in the sense that they are error-sensitive and time-consuming caused by the manual or chemical, sample- based screening of the products. For most liquids a decent monitoring method is missing. In view of this, the authors started exploring the potential of photonics to answer the question if food screening methods could be photonics-based. This paper gives an overview of our research of the past eighteen years. Autors: Wendy Meulebroeck;Hugo Thienpont;Heidi Ottevaere; Appeared in: IEEE Instrumentation & Measurement Magazine Publication date: Oct 2017, volume: 20, issue:5, pages: 46 - 55 Publisher: IEEE
» Photonics-Based Broadband RF Spectrum Measurement With Sliced Coherent Detection and Spectrum Stitching Technique
 Abstract:A novel photonics-based channelization approach is proposed for broadband radio frequency (RF) spectrum measurement with a single optical frequency comb, sliced coherent detection (SCD), and improved fast fourier transform-based digital signal processing. Through SCD, channel estimation and spectrum stitching, a broadband and complex RF spectrum can be detected and reconstructed with vector information in a high fidelity. A two-channel architecture as a proof of concept is characterized numerically with up to 40 GHz operation bandwidth, ≤12.5 GHz analysis bandwidth per channel, 113 dB·Hz2/3 spurious free dynamic range, and 161 dB·Hz linear dynamic range. The potentials for further system developments in practice are also discussed. Autors: Guangyu Gao;Lihua Lei; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 11 Publisher: IEEE
» Physical-Layer Security With Full-Duplex Transceivers and Multiuser Receiver at Eve
 Abstract:Full-duplex communication enables simultaneous transmission from both ends of a communication link, thereby promising significant performance gains. Generally, it has been shown that the throughput and delay gains of full-duplex communication are somewhat limited in realistic network settings, leading researchers to study other possible applications that can accord higher gains. The potential of full-duplex communication in improving the physical-layer security of a communication link is investigated in this contribution. We specifically present a thorough analysis of the achievable ergodic secrecy rate and the secrecy degrees of freedom with full-duplex communication in the presence of a half-duplex eavesdropper node, with both single-user decoding and multi-user decoding capabilities. For the latter case, an eavesdropper with successive interference cancellation and joint decoding capabilities is assumed. Irrespective of the eavesdropper capabilities and channel strengths, the ergodic secrecy rate with full-duplex communication is found to grow linearly with the log of the direct channel signal-to-noise-ratio (SNR) as opposed to the flattened out secrecy rate with conventional half-duplex communication. Consequently, the secrecy degrees of freedom with full-duplex is shown to be two as opposed to that of zero in half-duplex mode. Autors: Nurul Huda Mahmood;Imran Shafique Ansari;Petar Popovski;Preben Mogensen;Khalid A. Qaraqe; Appeared in: IEEE Transactions on Communications Publication date: Oct 2017, volume: 65, issue:10, pages: 4392 - 4405 Publisher: IEEE
» Physical-Statistical Modeling of Dynamic Indoor Power Delay Profiles
 Abstract:This paper presents a physical-statistical radio channel power delay profiles model for room-to-room communication systems combining the room electromagnetic theory for modeling deterministic channel components with a geometry-based stochastic channel model with time-variant statistics for modeling stochastic components. The deterministic channel component, i.e., mean power delay spectrum, is comprised of specularly reflected paths plus diffuse components due to scattering and diffraction. The specular components are modeled with a set Dirac function, whereas the diffuse components modeling approach is a room electromagnetic theory-based model. Dynamic indoor communication channels are characterized by a non-stationary time- and delay-fading process due to changes in the environment. We analyze and model the time-delay variability of channels using -factor for small-scale variations and the -location scale distribution parameters for large-scale variations. It turns out that these parameters cannot be assumed to be constant in time and delay. After modeling of time-delay variations of the first order statistics, we generate channel realizations with appropriate second order statistics. As the result, the presented model enables to describe the evolution of the power delay profile in the time domain. Autors: Evgenii Vinogradov;Aliou Bamba;Wout Joseph;Claude Oestges; Appeared in: IEEE Transactions on Wireless Communications Publication date: Oct 2017, volume: 16, issue:10, pages: 6493 - 6502 Publisher: IEEE
» Physically Secured Optical OFDM-PON by Employing Chaotic Pseudorandom RF Subcarriers
 Abstract:We propose a chaos-based physically-enhanced secure scheme for orthogonal frequency division multiplexing-based passive optical network (OFDM-PON). This scheme employs a pseudorandom number sequence generated by a chaotic logistic map to control the frequencies of RF subcarriers. Due to the characteristic of chaos, these chaotic frequencies of RF subcarriers are difficult to be decrypted by an eavesdropper, which could greatly enhance the security of OFDM-PON. An experiment with 10-Gb/s 16 QAM-OFDM data is successfully transmitted over 20-km fiber, and it has confirmed that the proposed security scheme can protect the system from an eavesdropper or attacker, while keep a good performance for legal optical network units. Autors: Chongfu Zhang;Wei Zhang;Xiujun He;Chen Chen;Huijuan Zhang;Kun Qiu; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 8 Publisher: IEEE
» Physiological Effects of Single- and Multi-Walled Carbon Nanotubes on Rice Seedlings
 Abstract:In this paper, single-walled carbon nano- tubes (SWCNTs) and multi-walled carbon nano- tubes (MWCNTs) were found to accelerate leaf growth and development of rice seedlings at a low concentration (20 mg/L), accompanied with the increased chlorophyll content and net photosynthetic rate (PN). Quantitative real-time polymerase chain reaction results indicated that both SWCNTs and MWCNTs significantly increased expression of genes associated with chloroplast development and cell sizes. Further analysis revealed that the abscisic acid content decreased and the gibberellin content increased while the content of and H2O2 was slightly elevated and the activities of antioxidative enzymes (SOD, EC 1.15.1.1, and POD, EC 1.11.1.7) were differently modulated after treatment with the carbon nanotube (CNT). These results suggest a possible link between reactive oxygen species and plant hormones under CNTs treatment to promote rice seedlings growth. Autors: Hao Zhang;Mengxia Yue;Xueke Zheng;Chengshen Xie;Hong Zhou;Lijia Li; Appeared in: IEEE Transactions on NanoBioscience Publication date: Oct 2017, volume: 16, issue:7, pages: 563 - 570 Publisher: IEEE
» PI and PWM Sliding Mode Control of POESLL Converter
 Abstract:The positive output elementary superlift-Luo converter (POESLLC) is a type of dc/dc converter. This dc/dc converter has an attractive advantage of a high voltage transfer gain as compared with other conventional dc/dc converters. Because of the voltage and load variations and also switching operation, the dynamic and static performances of the POESLLC are nonlinear and time varying. In order to achieve an excellent performance, a nonlinear controller is required. In this paper, a robust and fast response controller for voltage regulation of a POESLLC is presented. A proportional integral and pulse width modulation sliding mode controller are combined to control a third-order POESLLC. The proposed controller can be applied in the continuous conduction mode. Some simulations and experimental results are presented to show the effectiveness of the developed controller in different operating conditions. Furthermore, it will be shown that the developed controller is successful in suppressing the steady-state error of the output voltage of the POESLLC as well as the number of reduction of sensors. Autors: Hadi Nasiri Jazi;Alireza Goudarzian;Rohallah Pourbagher;Sayed Yaser Derakhshandeh; Appeared in: IEEE Transactions on Aerospace and Electronic Systems Publication date: Oct 2017, volume: 53, issue:5, pages: 2167 - 2177 Publisher: IEEE
» Piezoelectric Performance and Hydrostatic Parameters of Novel 2–2-Type Composites
 Abstract:This paper provides a detailed study of the structure—piezoelectric property relationships and the hydrostatic response of 2–2-Type composites based on relaxor-ferroelectric 0.72 Pb (Mg1/3Nb2/3)O3–0.28PbTiO3 single crystal (SC) material. Type I layers in the composite system are represented by a single-domain [111]-poled SC. Changes in the orientation of the crystallographic axes in the Type I layer are undertaken to determine the maximum values of the hydrostatic piezoelectric coefficients , , and , and squared figure of merit of the composite. The Type II layers are a 0–3 composite whereby inclusions of modified PbTiO3 ceramic are distributed in a polymer matrix. A new effect is described for the first time due to the impact of anisotropic elastic properties of the Type II layers on the hydrostatic piezoelectric response that is coupled with the polarization orientation effect in the Type I layers. Large hydrostatic parameters –400 mV m/N, –45 C/, and Pa are achieved in the composite based on the 0.72 Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 SC. Examples of the large piezoelectric anisotropy ( or ) are discussed. The hydrostatic parameters of this novel compositesystem are compared to those of conventional 2–2 piezocomposites. Autors: Vitaly Yu. Topolov;Christopher R. Bowen;Andrey V. Krivoruchko; Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control Publication date: Oct 2017, volume: 64, issue:10, pages: 1599 - 1607 Publisher: IEEE
» Pilot Optimization for Estimation of High-Mobility OFDM Channels
 Abstract:Obtaining channel state information is very crucial for realizing high-performance high-rate wireless communications. For an orthogonal frequency-division multiplexing (OFDM) system operating in a high-mobility environment such as in high-speed trains, a sequence of pilot samples is inserted in each OFDM symbol to track the fast-varying channel responses. For such a high-mobility environment, the design of pilot sequence to minimize the mean squared error (MSE) of the channel estimate under a linear minimum mean squared error (LMMSE) estimator poses a difficult polynomial fractional optimization problem. In this paper, we develop a path-following optimization procedure, which improves the MSE in every iteration and quickly converges at least to its locally-optimal solution. Each iterative solution is given in a closed form with very low computational complexity. The developed path-following procedure can also be adapted to design pilot sequences for the least-square and maximum-likelihood estimators. Extensive simulation results demonstrate the effectiveness and superior performance of the proposed solutions and algorithms when compared to the state-of-the-art algorithms in the literature. Autors: Zhichao Sheng;Hoang Duong Tuan;Ha H. Nguyen;Yong Fang; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Oct 2017, volume: 66, issue:10, pages: 8795 - 8806 Publisher: IEEE
» PJM Integrates Energy Storage: Their Technologies and Wholesale Products
 Abstract:PJM INTERConnection (PJM) was the first U.S. independent system operator/regional transmission organization (ISO/RTO) to demonstrate how battery energy storage resources provide frequency regulation services in a competitive market. Since its first pilot in 2009, PJM has integrated nearly 300 MW of advanced energy storage resources into its market. During this time period, ISO s/RTOs have developed rules to allow energy storage resources to participate in wholesale electricity markets. The Federal Energy Regulatory Commission (FERC) and state lawmakers have also taken steps to create an environment in which energy storage resources play an increasing role in the reliable operation of the power grid. This article outlines the storage technologies operating in PJM today and the wholesale products they provide to the market as well as discusses services that energy storage resources may provide in the future along with integration opportunities, resulting in a larger amount of storage deployed within the grid. Autors: Hong Chen;Scott Baker;Scott Benner;Aaron Berner;Jianwei Liu; Appeared in: IEEE Power and Energy Magazine Publication date: Oct 2017, volume: 15, issue:5, pages: 59 - 67 Publisher: IEEE
» Planar GaN-Based Blue Light-Emitting Diodes With Surface p-n Junction Formed by Selective-Area Si–Ion Implantation
 Abstract:A GaN-based blue light-emitting diode structure, featuring a surface GaN p-n junction formed by selective-area Si implantation on a p-GaN surface layer, serving as a carrier injector, is demonstrated. Blue InGaN/GaN multiple quantum wells (MQWs) located under the Si-implanted planar GaN p-n junction emit a single-peak spectrum without defect-related yellow luminescence (YL). The absence of YL-band is attributed to the fact that the Si-implanted GaN homojunction only behaves a carrier injector rather than a photon injector. In other words, the single-peak blue emission does not originate from optical pumping that UV light emitted from the surface GaN homojunction (i.e., the GaN band-edge emission) to pump the underlying blue InGaN/GaN MQWs. The analysis of current–voltage characteristics and dynamic resistance tentatively elucidate that the planar surface p-n junction induces extra current paths to facilitate the carrier injection at high current injection. Autors: Ming-Lun Lee;Yu-Hsiang Yeh;Zi-Yuan Liu;Kai-Jen Chiang;Jinn-Kong Sheu; Appeared in: IEEE Transactions on Electron Devices Publication date: Oct 2017, volume: 64, issue:10, pages: 4156 - 4160 Publisher: IEEE
» Planar Shared Antenna Structure for NFC and UHF-RFID Reader Applications
 Abstract:A novel shared antenna structure is presented in this communication for near-field communication and ultrahigh-frequency (UHF)-radio frequency identification (RFID) reader applications. This design is developed based on a circularly polarized gap-loaded loop antenna and then evolved to contain a two-turn coil for inductive coupling. The design procedure and the operating principles in the two scenarios are interpreted. Experimental results confirm the good performances of the proposed design with low profile and simple structure. The measured 15 dB impedance matching and 3 dB axial ratio bandwidths can fully cover the entire UHF-RFID band of 840–960 MHz. In the high-frequency band, the optimal matching circuit of the proposed structure is determined and an average transmission coefficient of 0.61 is achieved within the operating range of 50 mm. Autors: Meng-Shuang Wang;Yong-Xin Guo;Wen Wu; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Oct 2017, volume: 65, issue:10, pages: 5583 - 5588 Publisher: IEEE
» Planar Single/Dual-Band Crossovers With Large- Frequency Ratios Using Coupled Lines
 Abstract:Compact planar crossovers with large-frequency ratios using coupled lines for single-band and dual-band are proposed in this letter. Conventional coupled lines with different transmission lines are used to realize the single and dual passband. The center frequency of the single-band crossover and frequency ratio for the dual-band can be easily changed by changing the characteristic impedance of the coupled and transmission lines. Two compact planar crossovers located at 1.35 and 1.31/2.69 GHz are designed and measured. The measured results are in good agreement with the simulated ones. Autors: Yu Zhao;Wenjie Feng;Tianyu Zhang;Wenquan Che;Quan Xue; Appeared in: IEEE Microwave and Wireless Components Letters Publication date: Oct 2017, volume: 27, issue:10, pages: 870 - 872 Publisher: IEEE
» Polarization-Modulation, I/Q-Demodulation Photonic Bandpass Sampling for Wideband, Multicarrier RF Application
 Abstract:Radio frequency (RF) photonic link under phase or polarization modulation and coherent in-phase/quadrature (I/Q) demodulation (ΦM/IQ or PolM/IQ) has been reported with unprecedented dynamic range performance, benefiting from the ultrahigh linear transfer function of electro-optic phase modulator. But the ideal linear demodulation cannot be preserved during traditional down-conversion, which is a must from high-carrier application. In this paper, we propose and demonstrate that PolM/IQ link employing ultrashort optical bandpass sampling delivers both multicarrier down-conversion and full linearization. The pulse train, equivalently a frequency comb with uniform amplitude and phase in frequency domain, is able to down-convert signal and all nonlinear spurs that are collected by the following analog-to-digital convertor (ADC), so that the original linearization algorithm stands. Our method releases the requirement of ADC and digital processing greatly. The bandwidth after bandpass sampling is confined within the first Nyquist zone, and the minimum value can be as small as signal bandwidth, much less than original which should be several times of the maximum carrier frequency. We demonstrate such linearization experimentally with two dual-carrier RF signals as input, covering multiple octave spans. Autors: Jieyu Ning;Yitang Dai;Feifei Yin;Junyi Zhang;Jianqiang Li;Wangzhe Li;Kun Xu; Appeared in: IEEE Photonics Journal Publication date: Oct 2017, volume: 9, issue:5, pages: 1 - 8 Publisher: IEEE
» PolSAR Ship Detection Using Local Scattering Mechanism Difference Based on Regression Kernel
 Abstract:In this letter, the local scattering mechanism difference based on regression kernel (LSMDRK) is developed as a discriminative feature for ship detection. The LSMDRK measures the scattering mechanism dissimilarity of a center pixel to its neighboring pixels. A ship detection scheme is proposed based on the LSMDRK. The detection scheme consists of two stages. In the feature extraction stage, polarimetric target decomposition is required to improve the discriminative ability of the descriptor. In the detection stage, a saliency detection strategy is utilized to construct the saliency map. Then, local maximum detection is employed. Finally, an adaptive threshold method is designed to achieve the final detection. The effectiveness of the detection scheme is validated by a RADARSAT-2 data set. Experimental results demonstrate that the proposed method can acquire a better detection on weak targets and has much less false alarms than some classical detection methods. Autors: Jinglu He;Yinghua Wang;Hongwei Liu;Ning Wang; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Oct 2017, volume: 14, issue:10, pages: 1725 - 1729 Publisher: IEEE

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