#### Electrical and Electronics Engineering publications abstract of: 07-2017 sorted by title, page: 6

» Downlink Achievable Rate Analysis in Massive MIMO Systems With One-Bit DACs
 Abstract:In this letter, we investigate the downlink performance of massive multiple-input multiple-output (MIMO) systems where the base station is equipped with one-bit analog-to-digital/digital-to-analog converters (ADC/DACs). We assume that the base station employs the linear minimum mean-squared-error channel estimator and treats the channel estimate as the true channel to precode the data symbols. We derive an expression for the downlink achievable rate for matched-filter precoding. A detailed analysis of the resulting power efficiency is pursued using our expression of the achievable rate. Numerical results are presented to verify our analysis. In particular, it is shown that, compared with conventional massive MIMO systems, the performance loss in one-bit massive MIMO systems can be compensated for by deploying approximately 2.5 times more antennas at the BS. Autors: Yongzhi Li;Cheng Tao;A. Lee Swindlehurst;Amine Mezghani;Liu Liu; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1669 - 1672 Publisher: IEEE
» Downlink Interference Control in Heterogeneous Cellular Networks: Macroscopic and Microscopic Control
 Abstract:In heterogeneous cellular networks that consist of macrocells and small cells, efficient interference management schemes between macrocells and small cells are crucial for overall system performance. To mitigate intercell interference, we propose macroscopic and microscopic interference control schemes. First, as a macroscopic interference control scheme, we propose a dynamic coordinated silencing. This scheme dynamically controls optimal bandwidth silencing between macrocells and small cells. It is carried out from a system quality of service (QoS) perspective on a long-term basis. Second, as a microscopic interference control scheme, we propose a user QoS-based rate splitting. This scheme controls optimal transmit power and rate for the split messages of scheduled users. It works as the complements of the proposed macroscopic control and is carried out on a short-term basis. The performance evaluations with ten small-cell deployment in each macrocell confirm that the proposed macroscopic control offers and enhanced cell-average spectral efficiency when it is compared with soft fractional reuse control and static silencing control, respectively, and and enhanced cell-edge spectral efficiency when it is compared to partitioning-based control and static silencing control, respectively. Further, it is shown that the proposed microscopic control can additionally enhance cell-edge spectral efficiency by preventing users from being interfered in dead-zone area. Autors: Wonjong Noh;Kyunghun Jang; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5919 - 5932 Publisher: IEEE
» Driver Modeling for Detection and Assessment of Driver Distraction: Examples from the UTDrive Test Bed
 Abstract:Vehicle technologies have advanced significantly over the past 20 years, especially with respect to novel in-vehicle systems for route navigation, information access, infotainment, and connected vehicle advancements for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) connectivity and communications. While there is great interest in migrating to fully automated, self-driving vehicles, factors such as technology performance, cost barriers, public safety, insurance issues, legal implications, and government regulations suggest it is more likely that the first step in the progression will be multifunctional vehicles. Today, embedded controllers as well as a variety of sensors and high-performance computing in present-day cars allow for a smooth transition from complete human control toward semisupervised or assisted control, then to fully automated vehicles. Next-generation vehicles will need to be more active in assessing driver awareness, vehicle capabilities, and traffic and environmental settings, plus how these factors come together to determine a collaborative safe and effective driver-vehicle engagement for vehicle operation. This article reviews a range of issues pertaining to driver modeling for the detection and assessment of distraction. Examples from the UTDrive project are used whenever possible, along with a comparison to existing research programs. The areas addressed include 1) understanding driver behavior and distraction, 2) maneuver recognition and distraction analysis, 3) glance behavior and visual tracking, and 4) mobile platform advancements for in-vehicle data collection and human-machine interface. This article highlights challenges in achieving effective modeling, detection, and assessment of driver distraction using both UTDrive instrumented vehicle data and naturalistic driving data Autors: John H.L. Hansen;Carlos Busso;Yang Zheng;Amardeep Sathyanarayana; Appeared in: IEEE Signal Processing Magazine Publication date: Jul 2017, volume: 34, issue:4, pages: 130 - 142 Publisher: IEEE
» Dual Airgap Stator- and Rotor-Permanent Magnet Machines With Spoke-Type Configurations Using Phase-Group Concentrated Coil Windings
 Abstract:This paper presents an advanced design procedure for stator-based and rotor-based permanent magnet (PM) machines to improve the electromagnetic performance by incorporating the spoke-type magnet configurations, phase-group concentrated coil windings, and an unaligned arrangement of two rotors/stators. The dual-rotor switched flux PM machine (SFPMM), designated as the stator-PM machine, and the dual-stator spoke-type interior PM machine (S-IPMM), termed the rotor-PM machine, are designed by the proposed design procedure to obtain high torque density and low pulsating torques for direct-drive applications. A quantitative comparison is performed between the proposed SFPMM and S-IPMM, and a conventional SFPMM with concentrated windings is adopted as the referenced model to evaluate the contribution of the proposed design procedure. The machine performance including back electromotive force, cogging torque, and electromagnetic torque is first analyzed by a finite element method under the same operating conditions. Finally, a prototype of the dual-stator S-IPMM is manufactured, and some key simulation results are verified by the experimental tests. Autors: Wenliang Zhao;Dezhi Chen;Thomas A. Lipo;Byung-Il Kwon; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3327 - 3335 Publisher: IEEE
» Dual Mode Microwave Microfluidic Sensor for Temperature Variant Liquid Characterization
 Abstract:A dual mode, microstrip, microfluidic sensor was designed, built, and tested, which has the ability to measure a liquid’s permittivity at 2.5 GHz and, simultaneously, compensate for temperature variations. The active liquid volume is small, only around . The sensor comprises two quarter ring microstrip resonators, which are excited in parallel. The first of these is a microfluidic sensor whose resonant frequency and quality factor depend on the dielectric properties of a liquid sample. The second is used as a reference to adjust for changes in the ambient temperature. To validate this method, two liquids (water and chloroform) have been tested over a temperature range from 23 °C to 35 °C, with excellent compensation results. Autors: Ali A. Abduljabar;Nicholas Clark;Jonathan Lees;Adrian Porch; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Jul 2017, volume: 65, issue:7, pages: 2572 - 2582 Publisher: IEEE
» Dual Pricing Algorithm in ISO Markets
 Abstract:The challenge to create efficient market clearing prices in centralized day-ahead electricity markets arises from inherent nonconvexities in unit commitment problems. When this aspect is ignored, marginal prices may result in economic losses to market participants who are part of the welfare maximizing solution. In this essay, we present an axiomatic approach to efficient prices and cost allocation for a revenue neutral and nonconfiscatory day-ahead market. Current cost allocation practices do not adequately attribute costs based on transparent cost causation criteria. Instead we propose an ex post multipart pricing scheme, which we refer to as the dual pricing algorithm. Our approach can be incorporated into current day-ahead markets without altering the market equilibrium. Autors: Richard P. O'Neill;Anya Castillo;Brent Eldridge;Robin Broder Hytowitz; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 3308 - 3310 Publisher: IEEE
» Dual Two-Level Converters Based on Direct Power Control for an Open-Winding Brushless Doubly-Fed Reluctance Generator
 Abstract:This paper proposes a novel open-winding brushless doubly-fed reluctance generator (OW-BDFRG) with dual two-level converters in order to reduce the converter rating and switching frequency for large-scale wind turbine applications. The new converter topology is equivalent to a three-level converter directly connected to the control winding of typical BDFRG. The OW-BDFRG system with this topology structure requires lower converter rating and switching frequency, and has a more flexible control mode, better operation performance, and fault redundancy capability. For the OW-BDFRG, this paper also proposes a new control scheme combining direct power control (DPC) with sliding mode variable structure (SMVS) control to implement the power tracking. The voltage-vector switching table of DPC is redesigned according to the error signals of active and reactive powers of the power winding, as well as the sector location of control winding flux. The active and reactive powers of the OW-BDFRG can be directly decoupled and independently controlled by properly selecting the switching voltage vectors. The novelty of this paper lies in an OW-BDFRG topology driven by dual two-level converters to improve the system characteristics, and the use of SMVS control to improve the DPC accuracy and robustness to parameter variations. Finally, the effectiveness of the proposed system is verified through simulation and experimental studies. Autors: Shi Jin;Long Shi;Liancheng Zhu;Wenping Cao;Ting Dong;Fengge Zhang; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3898 - 3906 Publisher: IEEE
» Dual-Frequency Piezoelectric Endoscopic Transducer for Imaging Vascular Invasion in Pancreatic Cancer
 Abstract:Cancers of the pancreas have the poorest prognosis among all cancers, as many tumors are not detected until surgery is no longer a viable option. Surgical viability is typically determined via endoscopic ultrasound imaging. However, many patients who may be eligible for resection are not offered surgery due to diagnostic challenges in determining vascular or lymphatic invasion. In this paper, we describe the development of a dual-frequency piezoelectric transducer for rotational endoscopic imaging designed to transmit at 4 MHz and receive at 20 MHz in order to image microbubble-specific superharmonic signals. Imaging performance is assessed in a tissue-mimicking phantom at depths from 1 cm [contrast-to-tissue ratio (CTR) = 21.6 dB] to 2.5 cm (CTR = 11.4 dB), in ex vivo porcine vessels, and in vivo in a rodent. The prototyped 1.1-mm aperture transducer demonstrates contrast-specific imaging of microbubbles in a 200--diameter tube through the wall of a 1-cm-diameter porcine artery, suggesting such a device may enable direct visualization of small vessels from within the lumen of larger vessels such as the portal vein or superior mesenteric vein. Autors: Brooks D. Lindsey;Jinwook Kim;Paul A. Dayton;Xiaoning Jiang; Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control Publication date: Jul 2017, volume: 64, issue:7, pages: 1078 - 1086 Publisher: IEEE
» Dual-Mode Filtering Power Divider With High Passband Selectivity and Wide Upper Stopband
 Abstract:A novel microstrip dual-mode filtering power divider (FPD) is presented in this letter. Stemming from the distinctive voltage distribution along an open-ended one-wavelength () microstrip line, the dual-mode FPD is initially constructed by utilizing proper coupling topologies between the open-ended transmission line and two dual-mode resonators. Meanwhile, its good isolation performance is attained by introducing an isolation resistor between the two dual-mode resonators. Next, the explicit synthesis method is described to design the proposed FPD with prescribed performance. A prototype FPD at 2.4 GHz is in final implemented and measured. As theoretically expected, this proposed FPD exhibits better than 22-dB isolation within the entire operation band along with 17-dB harmonic suppression up to 7.5 GHz (3.1f0). Autors: Gang Zhang;Jianpeng Wang;Lei Zhu;Wen Wu; Appeared in: IEEE Microwave and Wireless Components Letters Publication date: Jul 2017, volume: 27, issue:7, pages: 642 - 644 Publisher: IEEE
» Dual-Scheduler Design for C/U-Plane Decoupled Railway Wireless Networks
 Abstract:Previously, we have proposed a C/U-plane (Control/User plane) decoupled railway wireless network in which higher frequency bands are adopted by small cells to provide wider available spectra for the U-plane of passengers' services. In order to guarantee reliable connectivity to wayside eNodeBs (eNBs), an onboard mobile relay (MR), consisting of two components, namely, MR-UE (User Equipment) and MR-AP (Access Point), is employed to forward passengers' services over backhaul links between MR-UE and wayside eNBs. The remaining problem here is how to utilize spectra effectively and efficiently under this new configuration. Since a given wayside eNB hosts only one single accessed user most of the time, we design an additional uplink scheduler for the MR-UE to self-manage the usage of uplink resources, avoiding the complicated uplink grant procedure commonly used in the conventional cellular systems. Moreover, we develop eNB schedulers to coordinate the spectra in small cells. To deal with occasional multi-user scenarios, we propose an uplink scheduler switcher for the macro cell to judge which uplink scheduler should be activated. Furthermore, an uplink resource allocation scheme with high spectrum efficiency is deliberately designed for the new dual-scheduler configuration. Finally, we carry out theoretical analysis and numerical simulations to demonstrate the effectiveness of our proposed scheme. Autors: Li Yan;Xuming Fang;Yuguang Fang;Xiangle Cheng; Appeared in: IEEE Transactions on Mobile Computing Publication date: Jul 2017, volume: 16, issue:7, pages: 1842 - 1855 Publisher: IEEE
» Dynamic $R_{\mathrm {ON}}$ of GaN-on-Si Lateral Power Devices With a Floating Substrate Termination
 Abstract:Dynamic ON-resistance () of 650-V GaN-on-Si lateral power devices with a floating Si-substrate termination is investigated. Compared with the grounded substrate termination, the floating substrate could deliver smaller dynamic under higher drain bias (> 400 V) switching operation, but leads to larger dynamic under low-drain bias (< 400 V). The underlying physical mechanisms are explained by the tradeoff between charge storage in the Si substrate and electron trapping effect in the GaN buffer layer. Autors: Gaofei Tang;Jin Wei;Zhaofu Zhang;Xi Tang;Mengyuan Hua;Hanxing Wang;Kevin J. Chen; Appeared in: IEEE Electron Device Letters Publication date: Jul 2017, volume: 38, issue:7, pages: 937 - 940 Publisher: IEEE
» Dynamic Clustering and User Association in Wireless Small-Cell Networks With Social Considerations
 Abstract:In this paper, a novel social network-aware user association in wireless small cell networks with underlaid device-to-device (D2D) communication is investigated. The proposed approach exploits strategic social relationships between user equipments (UEs) and their physical proximity to optimize the overall network performance. This problem is formulated as a matching game between UEs and their serving nodes (SNs) in which, an SN can be a small cell base station (SCBS) or an important UE with D2D capabilities. The problem is cast as a many-to-one matching game in which UEs and SNs rank one another using preference relations that capture both the wireless aspects (i.e., received signal strength, traffic load, etc.) and users’ social ties (e.g., UE proximity and social distance). Due to the combinatorial nature of the network-wide UE–SN matching, the problem is decomposed into a dynamic clustering problem in which SCBSs are grouped into disjoint clusters based on mutual interference. Subsequently, an UE–SN matching game is carried out per cluster. The game under consideration is shown to belong to a class of matching games with externalities arising from interference and peer effects due to users social distance, enabling UEs and SNs to interact with one another until reaching a stable matching. Simulation results show that the proposed social-aware user association approach yields significant performance gains, reaching up to , , and for 5th, 50th, and 95th percentiles for UE throughputs, respectively, as compared to the classical social-unaware baseline. Autors: Muhammad Ikram Ashraf;Mehdi Bennis;Walid Saad;Marcos Katz;Choong-Seon Hong; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6553 - 6568 Publisher: IEEE
» Dynamic Configuration of Partitioning in Spark Applications
 Abstract:Spark has become one of the main options for large-scale analytics running on top of shared-nothing clusters. This work aims to make a deep dive into the parallelism configuration and shed light on the behavior of parallel spark jobs. It is motivated by the fact that running a Spark application on all the available processors does not necessarily imply lower running time, while may entail waste of resources. We first propose analytical models for expressing the running time as a function of the number of machines employed. We then take another step, namely to present novel algorithms for configuring dynamic partitioning with a view to minimizing resource consumption without sacrificing running time beyond a user-defined limit. The problem we target is NP-hard. To tackle it, we propose a greedy approach after introducing the notions of dependency graphs and of the benefit from modifying the degree of partitioning at a stage; complementarily, we investigate a randomized approach. Our polynomial solutions are capable of judiciously use the resources that are potentially at user’s disposal and strike interesting trade-offs between running time and resource consumption. Their efficiency is thoroughly investigated through experiments based on real execution data. Autors: Anastasios Gounaris;Georgia Kougka;Ruben Tous;Carlos Tripiana Montes;Jordi Torres; Appeared in: IEEE Transactions on Parallel and Distributed Systems Publication date: Jul 2017, volume: 28, issue:7, pages: 1891 - 1904 Publisher: IEEE
» Dynamic Modeling, Analysis, and Testing of a Variable Buoyancy System for Unmanned Multidomain Vehicles
 Abstract:This paper presents the system design and dynamic model of an active variable buoyancy system (VBS) actuator with applications to unmanned multidomain vehicles. Unmanned multidomain vehicles have a unique concept of operations that require nontraditional VBS designs. We present a VBS actuator design that focuses on vehicle design objectives of high endurance, stealth, and loitering while underwater. The design consists of an elastic bladder housed within a rigid ballast tank, hydraulic pump, and proportionally controlled vent valve. Ambient surrounding water is the system working fluid and the elastic bladder serves to separate the gas–water interface, eliminating the risk of the compressed gas escaping when venting the water during extreme pitch maneuvers. A nonlinear analytic model of the VBS is derived and used to examine the parameter design space and the effects on water flow rate, actuation force, and energy efficiency. The VBS actuator design is shown to require a smaller, denser energy storage device than a comparable buoyancy system that uses consumable compressed air. A vehicle model is studied that features forward and aft VBS actuators, which enables vehicle pitch control by shifting the center of gravity along the vehicle's longitudinal axis. The coupling between the VBS actuator dynamics and vehicle dynamics is presented and discussed. A proof-of-concept demonstration is presented and compared to the analytical system model. Autors: Marc MacLeod;Matthew Bryant; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Jul 2017, volume: 42, issue:3, pages: 511 - 521 Publisher: IEEE
» Dynamic Path To Stability in LTE-Unlicensed With User Mobility: A Matching Framework
 Abstract:LTE-Unlicensed has recently captured intense attention from both academic and industrial fields. By integrating the unlicensed spectrum with the licensed spectrum, using carrier aggregation, LTE-Unlicensed users can experience enhanced transmission while maintaining the seamless mobility management and predictable performance. However, due to different transmission regulations, the coordination between LTE and Wi-Fi systems requires careful design. It is especially important to understand how to guarantee the transmission quality for LTE users and reduce Wi-Fi users’ performance degradation, under the impact of the co-channel interference. In other words, how can we solve the unlicensed resource allocation problem under both LTE and Wi-Fi transmission requirements? In this paper, we propose a matching theory framework to tackle this problem. Specifically, the coexistence between LTE and Wi-Fi systems, i.e., the interaction between LTE and Wi-Fi users, is modeled as a stable marriage game. The coexistence constraints are interpreted as the preference lists. Two semi-distributed solutions, namely, the Gale–Shapley and the random path to stability algorithms are proposed. In addition, to address the external effect in matching, the inter-channel cooperation algorithm is introduced. Last but not least, the resource allocation problem is studied with network dynamics and the proposed mechanisms are evaluated under two typical user mobility models. Autors: Yunan Gu;Chunxiao Jiang;Lin X. Cai;Miao Pan;Lingyang Song;Zhu Han; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4547 - 4561 Publisher: IEEE
» Dynamic Phosphor Sedimentation Effect on the Optical Performance of White LEDs
 Abstract:In this letter, we investigated the dynamic phosphor sedimentation effect on the optical performance of phosphor-converted light-emitting diodes (pcLEDs) with dispensed phosphor layer. To analyze the phosphor sedimentation effect, we realized two packaging structures to sediment phosphor particles above/outside LED chip separately. The phosphor sedimentation effect on the luminous efficiency and correlated color temperature (CCT) were tested by experiments, followed by a quantitative exploration to the mechanism by evaluating the angular color uniformity and light intensity distribution-based Monte Carlo ray-tracing simulations. Results show that phosphor sedimentation happened above LED chip will decrease CCT by 33.19%, and happened outside LED chip will increase CCT by 269%. For the conventional packaging structure, phosphor sedimentation will lead to the decreasing CCT at first and the increasing CCT soon afterwards, and the CCT variation is 39.62%. Autors: Xingjian Yu;Weicheng Shu;Run Hu;Bin Xie;Yupu Ma;Xiaobing Luo; Appeared in: IEEE Photonics Technology Letters Publication date: Jul 2017, volume: 29, issue:14, pages: 1195 - 1198 Publisher: IEEE
» Dynamic Robust Transmission Expansion Planning
 Abstract:Recent breakthroughs in transmission network expansion planning (TNEP) have demonstrated that the use of robust optimization, as opposed to stochastic programming methods, renders the expansion planning problem considering uncertainties computationally tractable for real systems. However, there is still a yet unresolved and challenging problem as regards the resolution of the dynamic TNEP problem, which considers the year-by-year representation of uncertainties and investment decisions in an integrated way. This problem has been considered to be a highly complex and computationally intractable problem, and most research related to this topic focuses on very small case studies or used heuristic methods and has lead most studies about TNEP in the technical literature to take a wide spectrum of simplifying assumptions. In this paper, an adaptive robust TNEP formulation is proposed for keeping the full dynamic complexity of the problem. The method overcomes the problem size limitations and computational intractability associated with dynamic TNEP for realistic cases. Numerical results from an illustrative example and the IEEE 118-bus system are presented and discussed, demonstrating the benefits of this dynamic TNEP approach with respect to classical methods. Autors: Raquel García-Bertrand;Roberto Mínguez; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 2618 - 2628 Publisher: IEEE
» Dynamics of Surface Streamer Plasmas at Atmospheric Pressure: Mixtures of Argon and Methane
 Abstract:A nonequilibrium atmospheric streamer discharge was investigated as a means to seed a large-gap arc breakdown. The dynamics of the streamer were analyzed with high speed imaging, photodiode light intensity, and current–voltage measurements. The temporal evolution of the discharge included a localized surface corona and a positive surface streamer. With the addition of an impurity gas (methane), the ionization was suppressed, which inhibited surface streamer propagation. The electron temperature was determined from time and spatially averaged spectra, coupled with a collisional–radiative model. The electron temperature in argon was measured at 1.25 eV for an electron density range of 1019 – 1020m–3. Partial local thermodynamic equilibrium calculations showed that the Ar II 4p states followed a Boltzmann distribution with an excitation temperature of 0.7 eV. The gas temperature was estimated at 815 K from a black-body distribution. The velocity of the surface streamer in argon was estimated at ~100 km/s with a diameter of . Autors: Michael V. Pachuilo;Francis Stefani;Roger D. Bengtson; Dipti;Rajesh Srivastava;Laxminarayan L. Raja; Appeared in: IEEE Transactions on Plasma Science Publication date: Jul 2017, volume: 45, issue:7, pages: 1776 - 1787 Publisher: IEEE
» E-MICE: Energy-Efficient Concurrent Exploitation of Multiple Wi-Fi Radios
 Abstract:The concurrent use of multiple Wi-Fi radios in individual frequency channels is a solution readily available today to the increase of a mobile station's communication capacity, but at the expense of occasional performance deterioration (when the heterogeneity of capacity between interfaces gets severe) and additional power consumption. This paper proposes a mobile-side solution for the concurrent use of multiple radios in a performance-aware and energy-efficient manner, with which a mobile station activates and deactivates radio interfaces dynamically according to traffic demands and a predicted capacity gain. To this end, the proposed solution is composed of multiple prediction algorithms and a control algorithm. Prediction when activating an additional radio interface is relatively difficult since no information of the disabled interface's current status (and the corresponding frequency channel's) is available at the time of prediction. Our experiments show that, despite different types and used channels, different radio interfaces have a strong correlation of received signal strengths and used PHY rates between them. Based on this observation, the proposed solution learns a correlation pattern between interfaces whenever multiple interfaces are active and makes prediction of the coverage, expected PHY rate and capacity impact of an inactive interface based on the learned correlation with a currently active interface. The design of the prediction algorithms are based on a simple or machine-learning technique (SVM). The control algorithm then keeps monitoring the utilization of active interfaces and, if any of them has utilization over a threshold, checks if each inactive interface is within coverage and a valid rate range based on an active interface's received signal strength. Finally, an action of a configuration change (either activation, deactivation, or no change) selected based on the prediction of the resulting capacity is applied. Testbed experiments - sing COTS dual-band Wi-Fi interfaces demonstrate that the solution can enhance throughput by up to 29.6 percent (in a close distance to AP) and at most halve power consumption compared to legacy aggregation while the gain varies depending on the location and traffic conditions. Autors: Yuris Mulya Saputra;Ji-Hoon Yun; Appeared in: IEEE Transactions on Mobile Computing Publication date: Jul 2017, volume: 16, issue:7, pages: 1870 - 1880 Publisher: IEEE
» EBG-Backed Flexible Printed Yagi–Uda Antenna for On-Body Communication
 Abstract:An electromagnetic bandgap (EBG) structure backed, printed Yagi–Uda antenna for on-body communication is proposed in this communication. The proposed antenna is flexible, made of copper foil tape and polyester sheet. The antenna operates at 2.4-GHz industrial, scientific and medical radio band. A printed Yagi–Uda is used to achieve high gain, endfire radiation pattern, and decreased path loss. An EBG surface is also used to reduce the frequency detuning of the antenna and specific absorption rate (SAR) while increasing the antenna gain when placed on human body. Antenna gain has been increased by 60%, and SAR has been decreased from 8.55 to 0.07 W/kg when the antenna is backed with EBG. Autors: B. Sakthi Abirami;Esther Florence Sundarsingh; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Jul 2017, volume: 65, issue:7, pages: 3762 - 3765 Publisher: IEEE
» Economic Analysis of Crowdsourced Wireless Community Networks
 Abstract:Crowdsourced wireless community networks can effectively alleviate the limited coverage issue of Wi-Fi access points (APs), by encouraging individuals (users) to share their private residential Wi-Fi APs with others. In this paper, we provide a comprehensive economic analysis for such a crowdsourced network, with the particular focus on the users' behavior analysis and the community network operator's pricing design. Specifically, we formulate the interactions between the network operator and users as a two-layer Stackelberg model, where the operator determining the pricing scheme in Layer I, and then users determining their Wi-Fi sharing schemes in Layer II. First, we analyze the user behavior in Layer II via a two-stage membership selection and network access game, for both small-scale networks and large-scale networks. Then, we design a partial price differentiation scheme for the operator in Layer I, which generalizes both the complete price differentiation scheme and the single pricing scheme (i.e., no price differentiation). We show that the proposed partial pricing scheme can achieve a good tradeoff between the revenue and the implementation complexity. Numerical results demonstrate that when using the partial pricing scheme with only two prices, we can increase the operator's revenue up to 124.44 percent comparing with the single pricing scheme, and can achieve an average of 80 percent of the maximum operator revenue under the complete price differentiation scheme. Autors: Qian Ma;Lin Gao;Ya-Feng Liu;Jianwei Huang; Appeared in: IEEE Transactions on Mobile Computing Publication date: Jul 2017, volume: 16, issue:7, pages: 1856 - 1869 Publisher: IEEE
» Eddy-Current Induction by a Coil Whose Axis is Perpendicular to that of a Tube
 Abstract:We have derived analytical expressions for the quasi-static time-harmonic electromagnetic field of a circular coil used to induce eddy currents in a tube or pipe, the axis of the coil being perpendicular to that of the conductor. The results are used to determine coil impedance variations with frequency and position due to induced current. The analysis is based on a derivation of the transverse electric field of a circular current filament in free space expressed as a single layer potential. Integration of the filament field yields the coil field and its impedance in the presence of a tube. We have used the theory and a numerical approximation in fitting the frequency dependence of experimental coil impedance and thereby determined accurate estimates of the electrical conductivity of an inconel tube and the coil lift-off. Finding these parameters is a preliminary step in evaluating coil interactions with flaws. Autors: Tao Wu;John R. Bowler;Theodoros P. Theodoulidis; Appeared in: IEEE Transactions on Magnetics Publication date: Jul 2017, volume: 53, issue:7, pages: 1 - 9 Publisher: IEEE
» Editorial Technical Communications Revisited
 Abstract:Presents a look at scholarly publishing, with particular emphasis on two different types of original research - peer-reviewed research articles and peer-reviewed technical communicaitons (TCs). Autors: N. Ross Chapman; Appeared in: IEEE Journal of Oceanic Engineering Publication date: Jul 2017, volume: 42, issue:3, pages: 509 - 510 Publisher: IEEE
» Effect of ALD-Al2O3 Passivated Silicon Quantum Dot Superlattices on p/i/n+ Solar Cells
 Abstract:The photovoltaic (PV) nature of the silicon (Si) quantum dot super lattice (QDSL) is studied with an atomic-layer-deposited aluminum oxide film (ALD-Al2O3) and a conventional sputtered-grown amorphous silicon carbide film (a-SiC). The QDSL structures act as an intermediate layer in a p/i/n+ Si solar cell. The QDSL consists of 4-nm Si on 2-nm SiC nanodisks (NDs) arrayed in an ALD-Al2O3 and a-SiC passivation matrix. Formation of Si-NDs was confirmed by bright field scanning transmission electron microscope. A significant PV response in generating a high photocurrent density of 30.15 mA/cm, open circuit voltage of 0.50 V, fill factor FF of 0.61, and efficiency of 9.12% was observed in ALD-Al2O3/QDSL solar cell with respect to a-SiC/QDSL solar cell with of 26.94 mA/cm, of 0.50 V, FF of 0.47, and of 6.42%. A wide range of photo-carrier transports by the ALD-Al2O3/QDSL structure is possible in the external quantum efficiency spectra with respect to a-SiC/QDSL solar cell. The enhanced PV performance of the QD solar cells was clarified in terms of simulating the absorption contributions for all possible tr- nsitions in the nanostructure with different passivation films. Autors: Mohammad Maksudur Rahman;Yi-Chia Tsai;Ming-Yi Lee;Akio Higo;Yiming Li;Yusuke Hoshi;Noritaka Usami;Seiji Samukawa; Appeared in: IEEE Transactions on Electron Devices Publication date: Jul 2017, volume: 64, issue:7, pages: 2886 - 2892 Publisher: IEEE
» Effect of Postoxidation Nitridation on Forward Current–Voltage Characteristics in 4H–SiC Mesa p-n Diodes Passivated With SiO2
 Abstract:An origin of shunt current, a ledge in forward current–voltage (–) characteristics, in 4H-SiC mesa p-n diodes was investigated by adopting various surface passivation processes. Experimental results indicated that the shunt current path is located along the mesa sidewall and the shunt current is enlarged with increasing NO-annealing period and temperature. Based on these results, we qualitatively explain that nitrogen-related positive charges near the SiC/SiO2 interface, which are formed by postoxidation nitridation, induce band bending and lowering of the diffusion potential along the mesa sidewall, resulting in occurrence of the shunt current. Autors: Satoshi Asada;Tsunenobu Kimoto;Jun Suda; Appeared in: IEEE Transactions on Electron Devices Publication date: Jul 2017, volume: 64, issue:7, pages: 3016 - 3018 Publisher: IEEE
» Effect of Tensile and Compressive Bending Stress on Electrical Performance of Flexible a-IGZO TFTs
 Abstract:We report the changes in device performance of flexible amorphous indium-gallium-zinc-oxide thin-film transistors (TFTs) by 1.65% tensile or compressive bending stress for 10 k times. The TFTs exhibit negative threshold voltage () shift and enhanced drain current (). TFT performance under repetitive tensile bending stress exhibits comparatively large threshold voltage shift ( V) than compressive bending stress ( V), which might be originated from both the generation of interface states ( and gap trap density (dN/dE) by /cm2 and /cm2 eV, respectively under tensile bending stress. These are much higher than those (: /cm2 and dN/dE: /cm2eV) for compressive bending. The increase in the DOS appears after both types of the bending stress which is related to the generation of oxygen vacancies. According to technology- computer aided design simulation, the 10 k times repetitive compressive bending stress generates donor like states ( cm and tensile bending stress generates cm at eV. Autors: Mohammad Masum Billah;Md Mehedi Hasan;Jin Jang; Appeared in: IEEE Electron Device Letters Publication date: Jul 2017, volume: 38, issue:7, pages: 890 - 893 Publisher: IEEE
» Effect on High-Intensity Fields of a Tough Hydrophone With Hydrothermal PZT Thick-Film Vibrator and Titanium Front Layer
 Abstract:A novel tough hydrophone was fabricated by depositing hydrothermally synthesized lead zirconate titanate polycrystalline film on the back-side surface of a titanium plate. Our developed tough hydrophone resisted damage in a high-pressure field (15 MPa) at a focal point of a sinusoidal continuous wave driven by a concave high-intensity focused ultrasound (HIFU) transducer with up to 50 W of power input to the sound source. The hydrophone was suitable for the HIFU field, even though the hydrophone has a flat-shape tip of 3.5 mm diameter, which is slightly larger than the wavelength of a few megahertz. In this paper, experiments are performed to assess the effect on the HIFU field of changing the shape of the tough hydrophone, with the aim of developing a tough hydrophone. The spatial distribution of the acoustic bubbles around the focal point was visualized by using ultrasonic diagnostic equipment with the tough hydrophone located at the focal point of the HIFU transducer. From the visualization, the trapped acoustic bubbles were seen to arise from the standing wave, which implies that the acoustic pressure is reduced by this cloud of acoustic bubbles that appeared during hydrophone measurement. Although cavitation and acoustic bubbles may be unavoidable when using high-intensity ultrasound, the estimated result of evaluating acoustic fields without misunderstanding by acoustic bubbles can be obtained by the aid of visualizing bubbles around the tough hydrophone. Autors: Nagaya Okada;Shinichi Takeuchi; Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control Publication date: Jul 2017, volume: 64, issue:7, pages: 1120 - 1126 Publisher: IEEE
» Effects of External Field Orientation on Permanent Magnet Demagnetization
 Abstract:This paper investigates how the orientation of the applied demagnetizing magnetomotive force (MMF) affects the demagnetization behavior of Nd-Fe-B magnets that are widely used for permanent-magnet synchronous machines (PMSMs). This paper designs and builds a customized test fixture that can produce a magnetic field with varying orientation and intensity to demagnetize magnet samples. A computer-controlled 2-D mapping device is used to record the flux density above the test samples. The measurement results are compared with the 3-D finite-element analysis simulations. The understanding and insights obtained from this paper will be used to improve the robustness of magnet design for high power density PMSMs with improved capability of withstanding demagnetization during overcurrent faults. Autors: Peng Peng;Han Xiong;Julia Zhang;Wanfeng Li;Franco Leonardi;Chuanbing Rong;Michael W. Degner;Feng Liang;Leyi Zhu; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3438 - 3446 Publisher: IEEE
» Effects of the Equatorial Electrojet on FM-Based Passive Radar Systems
» Efficiency Tangent [Enigmas, etc.]
 Abstract:Various puzzles, games, humorous definitions, or mathematical that should engage the interest of readers. Autors: Takashi Ohira; Appeared in: IEEE Microwave Magazine Publication date: Jul 2017, volume: 18, issue:5, pages: 134 - 134 Publisher: IEEE
» Efficient Chromatic Dispersion Compensation and Carrier Phase Tracking for Optical Fiber FBMC/OQAM Systems
 Abstract:Offset quadratic-amplitude modulation (QAM) based filterbank multicarrier (FBMC/OQAM) is an attractive candidate to improve the spectral containment of optical fiber communication systems, especially when considering a sufficiently high number of subcarriers. As for other multicarrier modulations, the chromatic dispersion (CD) compensation is simplified in FBMC/OQAM systems since it is performed in the frequency domain. Unfortunately, FBMC/OQAM systems are sensitive to the laser phase noise (PN). The PN becomes difficult to mitigate when the number of subcarriers increases due to the increased symbol period. It results in intercarrier interference and intersymbol interference due to the loss of OQAM orthogonality. In this paper, we consider the use of moderate numbers of subcarriers to allow for simpler PN tracking. Consequently, more advanced CD compensation methods are required and a trade-off between CD and PN compensations needs to be studied. In this paper, the frequency sampling equalizer is used for the CD compensation, whereas an innovative adaptive maximum likelihood estimator is used for the PN compensation. A methodology is then presented to analyze this performance trade-off between CD and PN compensations, and design the desirable system parameters such as the number of subcarriers and the equalizer length. This is illustrated in the case of a terrestrial long-haul FBMC/OQAM transmission system, with 400-kHz laser linewidth and a 1000-km optical link. Autors: Trung-Hien Nguyen;François Rottenberg;Simon-Pierre Gorza;Jérome Louveaux;François Horlin; Appeared in: Journal of Lightwave Technology Publication date: Jul 2017, volume: 35, issue:14, pages: 2909 - 2916 Publisher: IEEE
» Efficient Descriptor-Based Segmentation of Parotid Glands With Nonlocal Means
 Abstract:Objective: We introduce descriptor-based segmentation that extends existing patch-based methods by combining intensities, features, and location information. Since it is unclear which image features are best suited for patch selection, we perform a broad empirical study on a multitude of different features. Methods: We extend nonlocal means segmentation by including image features and location information. We search larger windows with an efficient nearest neighbor search based on kd-trees. We compare a large number of image features. Results: The best results were obtained for entropy image features, which have not yet been used for patch-based segmentation. We further show that searching larger image regions with an approximate nearest neighbor search and location information yields a significant improvement over the bounded nearest neighbor search traditionally employed in patch-based segmentation methods. Conclusion: Features and location information significantly increase the segmentation accuracy. The best features highlight boundaries in the image. Significance: Our detailed analysis of several aspects of nonlocal means-based segmentation yields new insights about patch and neighborhood sizes together with the inclusion of location information. The presented approach advances the state-of-the-art in the segmentation of parotid glands for radiation therapy planning. Autors: Christian Wachinger;Matthew Brennan;Greg C. Sharp;Polina Golland; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Jul 2017, volume: 64, issue:7, pages: 1492 - 1502 Publisher: IEEE
» Efficient Four-Coil Wireless Power Transfer for Deep Brain Stimulation
 Abstract:This paper demonstrates a closed-loop wireless power transfer (WPT) system for deep brain stimulation-implanted biomedical applications. A novel two-layer PCB FR4 coil design is proposed as a second coil for enlarging the WPT efficiency. High-efficiency implantable WPT technology was achieved by applying an inner dual-layer printed spiral coil (PSC) and outer helical coil and this coordinated with a T-type impedance-matching network. To reduce the loading effect, which lowers Q factor in implanted devices, four-coil WPT systems are recommended compared with two- or three-coil WPT systems. A practical four-coil system was implemented for verification, for which a dual-layer printed circuit board composed of a PSC, with a load loop on the other side of FR4, was designed and implemented around the system on a chip. PSCs for biomedical implants can be optimized by designing the geometric parameters. The implant coil occupies an area measuring mm, and is implemented on both an FR4 board and an implantable flexible substrate with the optimized geometric parameters. Finally, the transmission efficiencies of using FR4 and flexible printed circuit boards, at a distance of 10 mm, were 19.1% and 14.8% through the air and 11.7% and 7.7% through the tissue, respectively, thus enabling the supply of milliwatts of power to the stimulation circuits, and successfully demonstrating the stimulation tissue model with a V/I output current of up to 180 . Autors: Chin-Lung Yang;Chung-Kai Chang;Shuenn-Yuh Lee;Soon-Jyh Chang;Lih-Yih Chiou; Appeared in: IEEE Transactions on Microwave Theory and Techniques Publication date: Jul 2017, volume: 65, issue:7, pages: 2496 - 2507 Publisher: IEEE
» Efficient FPGA Implementation of Low-Complexity Systolic Karatsuba Multiplier Over $GF(2^{m})$ Based on NIST Polynomials
 Abstract:Systolic implementation of Karatsuba algo- rithm (KA)-based digit-serial multiplier over on field- programmable gate array (FPGA) platforms has many attractive features, such as efficient tradeoff in area-time complexity and high-throughput rate. But on the other side, it suffers from high register-complexity, which leads to increase in area and power consumption. In this paper, we present an algorithm and architecture for efficient FPGA implementation of KA-based digit-serial systolic multiplier over based on the National Institute of Standards and Technology (NIST) recommended polynomials. A number of efficient techniques have been explored and used to realize efficient implementation of these multipliers. First, we propose a novel KA-based approach, where the computational complexity is significantly reduced compared with the existing one. Second, we propose efficient register minimization techniques, such as redundant register removal, two-stage pipelining, and register sharing to reduce the register complexity of the proposed structure. Third, we adopt an efficient FPGA-specific digit-parallel implementation strategy to optimize the area-time–power complexities of the proposed structure on FPGA platforms. The results obtained from FPGA synthesis indicate that the proposed multiplier (for field based on NIST trinomial ) has significantly lower area–time–power complexities than the existing designs, e.g., the proposed structure could achieve 65.7% and 73.6% reduction on area-delay product and power-delay product over the best of existing KA-based systolic structures, respectively. Autors: Jiafeng Xie;Pramod Kumar Meher;Mingui Sun;Yuecheng Li;Bo Zeng;Zhi-Hong Mao; Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers Publication date: Jul 2017, volume: 64, issue:7, pages: 1815 - 1825 Publisher: IEEE
» Efficient Hybrid Grouping Spectrum Assignment to Suppress Spectrum Fragments in Flexible Grid Optical Networks
 Abstract:Flexible grid optical networks (FONs) can accommodate diverse kinds of service connections with higher networking flexibility and spectrum-utilization efficiency by employing a finer resource allocation granularity (known as frequency slot) and a more sophisticated path-routing and resource-allocation algorithm (known as routing and spectrum assignment algorithm), when compared to the traditional wavelength division multiplexing optical networks. However, the continuity and the contiguity constraints in spectrum allocation may possibly introduce spectrum fragments, which cannot be utilized by the subsequent service connections and thus reduce the amount of available resources as well as the networking flexibility in FONs. Therefore, many algorithms have been proposed to decrease the amount of spectrum fragments by re-optimizing the fragmented resources. These algorithms are known as spectrum defragmentation algorithms, which always induce traffic disruption or require extra components. In order to avoid traffic disruption and the requirement of extra components, some grouping RSA algorithms have been proposed to suppress spectrum fragments from their generation by pre-dividing the spectrum resources into several either fixed or variable groups. However, since the spectrum resources in one group can only be assigned to the service connections of one specific kind, the flexibility of these grouping algorithms is always limited by the kinds of service connections. In this paper, we introduce hybrid grouping mechanism into spectrum assignment and propose a hybrid-group-based RSA algorithm, most-used-first hybrid grouping (MUFHG) RSA algorithm, to suppress the spectrum fragments generated in FONs. By employing hybrid grouping mechanism, the proposed MUFHG algorithm sorts the spectrum resources into several flexible groups with specified allocation starting FSs. And each spectrum group can accommodate several kinds of service connections if the bandwidth requirements of - hese service connections have multiple relations, which guarantees that the remained or the released spectrum resources in each group can always be re-used. Therefore, spectrum fragments are only generated in the spectrum bands between two adjacent flexible groups. In this way, the proposed hybrid-group-based algorithm can significantly suppress spectrum fragments from their generation. Besides, the proposed MUFHG algorithm helps improve the blocking performance of the network by employing the most-used-first strategy to maximize the number of less frequently used spectrum resources for subsequent service connections. The simulation results indicate that the proposed MUFHG algorithm gains notable reductions in both spectrum fragments and bandwidth blocking probability with neither traffic disruption nor extra components. Autors: Yang Qiu;Jing Xu; Appeared in: Journal of Lightwave Technology Publication date: Jul 2017, volume: 35, issue:14, pages: 2823 - 2832 Publisher: IEEE
» Efficient Immobilization of Tyrosinase Enzyme on Layered Double Hydroxide Hybrid Nanomaterials for Electrochemical Detection of Polyphenols
 Abstract:Gold screen-printed electrodes coated with thin films of layered double hydroxides containing cobalt and aluminium (Co1.57 Al(OH)xSO4, shortened as CoAl) have been investigated for the design of an electrochemical tyrosinase-based biosensor used for the detection of a complex mixture of polyphenols extracted from green tea. Physicochemical analyses show that the resulted biosensor exhibits very attractive characteristics: a high sensitivity, a large dynamic range (up to 1000 ng.mL), and very low limits of detection (0.33 pg.mL and 0.03 pg.mL for oxidation and reduction, respectively). Autors: Asma Soussou;Ibtissem Gammoudi;Fabien Moroté;Adel Kalboussi;Touria Cohen-Bouhacina;Christine Grauby-Heywang;Zouhair M. Baccar; Appeared in: IEEE Sensors Journal Publication date: Jul 2017, volume: 17, issue:14, pages: 4340 - 4348 Publisher: IEEE
» Efficient Memristor Model Implementation for Simulation and Application
 Abstract:In this paper, we propose a novel Verilog-A based memristor model for effective simulation and application. Our proposed model captures desired nonlinear characteristics using voltage-based state control. This model is flexible and accurate, it can exhibit all the behaviors of HP memristive device and a general class memristive device resistive random access memory which is important in logic and memory design. Furthermore, we can antiserially connect two proposed models to capture the ideal – characteristics of complementary resistive switch (CRS). We demonstrate that our proposed CRS model-based crossbar arrays can significantly reduce sneak path currents with high noise margin compared to traditional memristor-based architectures. Autors: Xiaoping Wang;Bowen Xu;Lin Chen; Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems Publication date: Jul 2017, volume: 36, issue:7, pages: 1226 - 1230 Publisher: IEEE
» Efficient Positioning in MIMO Radars With Widely Separated Antennas
 Abstract:An algebraic closed-form solution for locating a moving target using a distributed multiple-input multiple-output radar system is proposed. The position and velocity of the target are estimated by presenting a two-stage weighted least squares algorithm. In contrast to existing research, the proposed estimator is shown analytically to be approximately unbiased and its variance is equal to the Cramer-Rao lower bound. Numerical simulations corroborate the theoretical studies and demonstrate the superiority of this algorithm over the existing methods. Autors: Rouhollah Amiri;Fereidoon Behnia;Mohammad Amin Maleki Sadr; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1569 - 1572 Publisher: IEEE
» Efficient Random-Access Scheme for Massive Connectivity in 3GPP Low-Cost Machine-Type Communications
 Abstract:In order to facilitate low-cost network connection of many devices, machine-type communication (MTC) has evolved to low-cost MTC (LC-MTC) in the third-generation partnership project standard. LC-MTC should be able to effectively handle intensive accesses through multiple narrowband random-access channels (RACHs) assigned within the bandwidth of a long-term evolution system. As the number of MTC devices and their congestion rapidly increase, the random-access scheme for the LC-MTC RACH needs to be improved. This paper presents a novel random-access scheme that introduces virtual preambles of LC-MTC devices and associates them with RACH indexes to effectively discern LC-MTC devices. In comparison with the sole use of preambles, our scheme allows an LC-MTC device to better choose a unique virtual preamble. Thereby, the probability of successful accesses of LC-MTC devices increases in contention-based random-access environments. We experimentally assessed our scheme, and the results show that our scheme performs better than the existing preamble-based scheme in terms of collision probability, access delay, and access blocking probability. Autors: Jun Suk Kim;Sungkil Lee;Min Young Chung; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6280 - 6290 Publisher: IEEE
» Efficient Resource Allocation in Cognitive Networks
 Abstract:Cognitive radio (CR) in conjunction with multiple-input multiple-output (MIMO) orthogonal frequency-division multiple access is a candidate technology for future mobile radio networks. The short communication range of underlay CR systems is commonly a major limiting factor. In this paper, we propose a computationally and spectrally efficient resource allocation scheme for multiuser MIMO orthogonal-frequency-division-multiplexing-based underlay CR networks to provide good spectral efficiency gain and, therefore, increased communication range. Since the formulated optimization problem defines a mixed-integer programming (combinatorial task) that is hard to solve, we propose a two-phase scheme to produce efficient solutions for both the downlink and the uplink. Particularly, the first procedure elaborates on an adaptive precoding that is characterized by spectral efficiency due to the degrees of freedom it can provide. The second procedure develops a fast subcarrier mapping algorithm, which can be worked out through optimal power distribution among the CR users. The proposed scheme is optimal for the downlink but, however, near-optimal for the uplink. Simulation results demonstrate the bandwidth and computational efficiencies of the proposed scheme compared with the state of the art. Autors: Abdullah Yaqot;Peter Adam Hoeher; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6349 - 6361 Publisher: IEEE
» Efficient Uncertainty Quantification in Stochastic Economic Dispatch
 Abstract:Stochastic economic dispatch models address uncertainties in forecasts of renewable generation output by considering a finite number of realizations drawn from a stochastic process model, typically via Monte Carlo sampling. Accurate evaluations of expectations or higher order moments for quantities of interest, e.g., generating cost, can require a prohibitively large number of samples. We propose an alternative to Monte Carlo sampling based on polynomial chaos expansions. These representations enable efficient and accurate propagation of uncertainties in model parameters, using sparse quadrature methods. We also use Karhunen–Loève expansions for efficient representation of uncertain renewable energy generation that follows geographical and temporal correlations derived from historical data at each wind farm. Considering expected production cost, we demonstrate that the proposed approach can yield several orders of magnitude reduction in computational cost for solving stochastic economic dispatch relative to Monte Carlo sampling, for a given target error threshold. Autors: Cosmin Safta;Richard L.-Y. Chen;Habib N. Najm;Ali Pinar;Jean-Paul Watson; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 2535 - 2546 Publisher: IEEE
» Efficient Utilization of Rare Earth Permanent-Magnet Materials and Torque Ripple Reduction in Interior Permanent-Magnet Machines
 Abstract:This paper proposes a new interior permanent-magnet machine (IPMM) design in which the rotor consists of several rotor segments arranged in the axial direction, aiming to improve the utilization of rare earth permanent-magnet (PM) materials and reduce the torque ripple. The proposed design is optimized to feature a reduction of rare earth PM materials and a reduction of ripple torque ratio compared with the Camry 2007 design, which uses the conventional pole-shaping technique to suppress its torque ripple. Although the torque is reduced by , the torque per magnet weight is improved by , indicating the PMs are more efficiently used in the proposed design. The designs are verified by 3-D finite element. Despite the small torque reduction, the efficiency of the proposed design is still about the same as the Camry design. Autors: Zhentao S. Du;Thomas A. Lipo; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3485 - 3495 Publisher: IEEE
» Efficiently List-Decodable Punctured Reed-Muller Codes
 Abstract:The Reed–Muller (RM) code, encoding -variate degree- polynomials over for , with its evaluation on , has a relative distance and can be list decoded from a fraction of errors. In this paper, for , we give a length-efficient puncturing of such codes, which (almost) retains the distance and list decodability properties of the RM code, but has a much better rate. Specifically, when , we give an explicit rate puncturing of RM codes, which have a relative distance at least and efficient list decoding up to error fraction. This almost matches the performance of random puncturings, which work with the weaker field size requirement . We can also improve the field size requirement to the optimal (up to constant factors) , at the expense of a worse list decoding radius of and rate . The first of the above tradeoffs is obtained by substituting for the variables functions with carefully chosen pole orders from an algebraic function field; this leads to a puncturing for which the RM code is a subcode of a certain algebraic-geometric code (which is known to be efficiently list decodable). The second tradeoff is obtained by concatenating this construction with a Reed–Solomon-based multiplication friendly pair, and using the list recovery property of algebraic-geometric codes. Autors: Venkatesan Guruswami;Lingfei Jin;Chaoping Xing; Appeared in: IEEE Transactions on Information Theory Publication date: Jul 2017, volume: 63, issue:7, pages: 4317 - 4324 Publisher: IEEE
» Electric Spring for Voltage and Power Stability and Power Factor Correction
 Abstract:Electric spring (ES), a new smart grid technology, has earlier been used for providing voltage and power stability in a weakly regulated/stand-alone renewable energy source powered grid. It has been proposed as a demand-side management technique to provide voltage and power regulation. In this paper, a new control scheme is presented for the implementation of the ES, in conjunction with noncritical building loads like electric heaters, refrigerators, and central air conditioning system. This control scheme would be able to provide power factor correction of the system, voltage support, and power balance for the critical loads, such as the building's security system, in addition to the existing characteristics of ES of voltage and power stability. The proposed control scheme is compared with original ES's control scheme where only reactive power is injected. The improvised control scheme opens new avenues for the utilization of the ES to a greater extent by providing voltage and power stability and enhancing the power quality in the renewable energy powered microgrids. Autors: Jayantika Soni;Sanjib Kumar Panda; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3871 - 3879 Publisher: IEEE
» Electrical and Optical Impulse Response of High-Speed Micro-OLEDs Under UltraShort Pulse Excitation
 Abstract:The electric and optical impulse response of two types of high-speed OLED (HSOLED) driven by ultrashort electrical pulses is investigated. The two HSOLED were designed and manufactured to be characterized in the presence of electrical pulses ranging from 10 to 100 ns in duration and a repetition rate of 10 Hz. The impact of the OLED geometry and the fabrication process on the time response is investigated. This is the first time that an optimized HSOLED exhibits an electrical time response as low as 2.1±0.6 ns and also shorter than the device optical decay time (9.8± 0.2 ns). Moreover, the HSOLED measured current density reaches 3.0 kA/cm2, the highest value reported in the literature, with state-of-the-art electroluminescence of 12 W/cm2. Autors: Lei Zeng;Alex Chamberlain Chime;Mahmoud Chakaroun;Souheil Bensmida;Homere Nkwawo;Azzedine Boudrioua;Alexis P. A. Fischer; Appeared in: IEEE Transactions on Electron Devices Publication date: Jul 2017, volume: 64, issue:7, pages: 2942 - 2948 Publisher: IEEE
» Electrical Loss Minimization Technique for Wind Generators Based on a Comprehensive Dynamic Modeling of Induction Machines
 Abstract:This paper proposes a novel model-based electrical loss minimization technique (ELMT), whose main original contribution lies in the overall power loss function which has been derived from a comprehensive dynamic space-vector model of the induction machine (IM) including the iron losses, expressed in the rotor flux-oriented reference frame. Such a loss formulation, obtained from the IM input–output power balance, is more general and accurate than the others in the literature; consequently, the expression of the optimal efficiency reference flux to be given to the field-oriented system is more general and accurate too. The proposed ELMT has been integrated into an IM-based wind generation system including a previously developed maximum power point tracking based on a growing neural gas artificial neural network. The obtained results show that the new formulation of the overall power losses of the IM leads to an increase of the IM efficiency with respect to the classic loss equation proposed in the scientific literature. The integration of the proposed ELMT in a real wind generation system leads to an increase of the active power injected into the grid ranging from 33% at high wind speeds up to 200% at low wind speeds. Autors: Maria Carmela Di Piazza;Massimiliano Luna;Marcello Pucci; Appeared in: IEEE Transactions on Industry Applications Publication date: Jul 2017, volume: 53, issue:4, pages: 3696 - 3706 Publisher: IEEE
» Electrical Modeling and Analysis of Cu-CNT Heterogeneous Coaxial Through-Silicon Vias
 Abstract:An equivalent-circuit model of Cu-carbon nanotube heterogeneous coaxial through-silicon vias (HCTSVs) in 3-D integrated circuits (3-D ICs) is proposed in this paper. Based on the complex effective conductivity method, the resistances and inductances of Cu-single walled carbon nanotube (SWCNT) HCTSVs and Cu-multi walled carbon nanotube (MWCNT) HCTSVs are compared with that of Cu coaxial through-silicon vias (CTSVs). Furthermore, using the proposed model, the magnitudes of their insertion losses are compared. It is shown that the transmission performance of Cu-SWCNT HCTSVs with higher metallic fraction and Cu-MWCNT HCTSVs is better than that of Cu CTSVs, and the improvement of Cu-MWCNT HCTSVs is more obvious at high frequencies. Finally, the transmission characteristics of Cu-MWCNT HCTSVs are analyzed deeply to provide helpful design guidelines for them in future high-speed 3-D ICs. Autors: Qijun Lu;Zhangming Zhu;Yintang Yang;Ruixue Ding;Yuejin Li; Appeared in: IEEE Transactions on Nanotechnology Publication date: Jul 2017, volume: 16, issue:4, pages: 695 - 702 Publisher: IEEE
» Electrical Modeling and Analysis of Differential Dielectric-Cavity Through-Silicon via Array
 Abstract:The parasitic parameters and equivalent electrical model of differential dielectric-cavity through-silicon via (DDC-TSV) array on traditional low-resistivity silicon (LRSi) are proposed in this letter. TSV plugs are placed in the dielectric-cavity etched on LRSi. Each analytical formula in the model is established as the fuction of various physical geometries. The resistance–inductance–capacitance–conductance model and S-parameters of the DDC-TSV array are constructed by the Advanced Design System (ADS), which is verified by the 3-D full-wave electromagnetic solver High Frequency Simulator Structure (HFSS). Simulation results of the ADS and HFSS accord well with each other with frequencies up to 100 GHz, which shows good accuracy of the proposed model. Autors: Xiaoxian Liu;Zhangming Zhu;Yintang Yang;Ruixue Ding;Yuejin Li; Appeared in: IEEE Microwave and Wireless Components Letters Publication date: Jul 2017, volume: 27, issue:7, pages: 618 - 620 Publisher: IEEE
» Electrochemical Rectifier Maintenance: A Primer on Preventing Downtime and Expensive Repairs
 Abstract:Electrochemical power converters (rectifiers) are robust, reliable dc power supplies when first installed. They produce tens of megawatts of power 24/7 and have a typical design life of more than 20 years. Because industrial managers have become accustomed to this reliability, they often allow demands in other parts of a plant to divert maintenance resources from these machines that are so vital to production. Rectifiers are custom made, and a lack of maintenance often results in extensive downtime and costly repairs. This article provides a review of maintenance procedures and industry best practices, based on manufacturers’ recommendations, 25 years of rectifier industry experience, and lessons learned within a wide variety of operating electrochemical plants. Autors: Paul C. Buddingh; Appeared in: IEEE Industry Applications Magazine Publication date: Jul 2017, volume: 23, issue:4, pages: 57 - 65 Publisher: IEEE
» Electronic Transport and Light Response of Air-Stable n-Type Organic Chlorophenyl-Substituted Perylene Diimide Microribbons
 Abstract:We report a new n-type single-crystalline microribbon based on a chlorophenyl-substituted perylene tetracarboxylic diimide derivative via solution-phase self-assembly. Electronic transport, environmental stability, and photoresponse properties of these microribbons are studied using field-effect transistors. Transistors based on a network of the as-prepared microribbons have moderate electron mobilities and ON/OFF current ratios on the order of cm2/ and –, respectively. The lifetime test of microribbon devices under various humidity conditions is found to be very sustainable over 100 days. Moreover, illuminating these microribbons could profoundly induce photocurrents in the visible light range, presenting good responsivity of 9.5 A/W and a high external quantum efficiency up to 2000% under 1.9 mW/cm2. In addition, these microribbon devices are processed from solution-phase at temperatures below 100 °C, making the technology a viable candidate for low-cost and plastic-based organic optoelectronic applications. Autors: Chao-Yuan Tan;Pin-Yen Tseng;Gen-Wen Hsieh; Appeared in: IEEE Transactions on Electron Devices Publication date: Jul 2017, volume: 64, issue:7, pages: 2935 - 2941 Publisher: IEEE
» Electronic Visits in Primary Care: Modeling, Analysis, and Scheduling Policies
 Abstract:Primary care, the backbone of the nation’s healthcare system, is at the risk of collapse. Patients are dissatisfied due to poor access to care, and physicians are unhappy and burning out with an enormous amount of tasks. To improve the primary care access, many healthcare organizations have introduced electronic visits (or e-visits) to provide patient-physician communications through securing messages. In this paper, we introduce an analytical model to study e-visits in primary care clinics. Analytical formulas to evaluate the mean and variance of the patient length of visit in primary care clinics with e-visits are derived. System properties are investigated. In addition, comparisons of different scheduling policies between the office and the e-visits are carried out. The first come first serve, preemptive-resume, and non-preemptive policies are studied and the results show that the first come first serve policy typically leads to the best performance.Note to Practitioners—The primary care delivery system is under a lot of strain. Due to population growth and aging, and the expanded healthcare insurance coverage, the demand for primary care services has increased substantially in the past years. Patients have difficulty of getting timely access to care, while primary care physicians are facing insurmountable tasks. Electronic visit, or e-visit, as an alternative to the traditional office visit, provides an innovative way of patient-physician communication through securing messages. The successful implementation of e-visit relies on a proper understanding of the impact of e-visit on care access, and an appropriate design and scheduling of workforce and operations. Therefore, the objective of this paper is to develop an analytical model of the primary care delivery with e-visits, using which one can investigate the impact of e-visits on patient accessibility. In particular, the average value and variance - f patients’ length of visit for their encounters are evaluated. Different policies for physicians to schedule office and e-visit patients are compared. In addition, physicians’ nondirect care activities, such as billings and documentations, are also considered in the model. Autors: Xiang Zhong;Jingshan Li;Philip A. Bain;Albert J. Musa; Appeared in: IEEE Transactions on Automation Science and Engineering Publication date: Jul 2017, volume: 14, issue:3, pages: 1451 - 1466 Publisher: IEEE
» Embedded Systems Feel the Beat in New Orleans: Highlights from the IEEE Signal Processing Cup 2017 Student Competition [SP Competitions]
 Abstract:Presents information and highlights from the IEEE Signal Processing Cup 2017 Student Competition. Autors: Craig T. Jin;Matthew E.P. Davies;Patrizio Campisi; Appeared in: IEEE Signal Processing Magazine Publication date: Jul 2017, volume: 34, issue:4, pages: 143 - 170 Publisher: IEEE
» Emitter Spacer Layers Influence on the Dynamic Characteristics of Resonant-Tunneling Diode
 Abstract:Within the framework of the coherent quantum-mechanical model, which is based on the solution of the time-dependent Schrödinger equation with exact open boundary conditions, we have numerically analyzed the behavior of the InGaAs/AlAs resonant-tunneling diode (RTD) in an alternating-current electric field in the presence of spacer layers. It is shown that the interaction of the energy levels in a quantum well of the RTD, and the same in a quantum well of the emitter spacer, leads to splitting of these levels, which sharply increases the active current of RTD. In this case, the value of the active current at the finite frequencies may exceed the active current within the low-frequency limits. For RTD, heterostructure considered active current at frequency 1.77 THz takes its maximum value at the thickness of the emitter spacer equals to 6.5 nm exceeding the corresponding value in the absence of the spacer by the factor of 32. The results obtained in this paper may be useful to improve the frequency characteristics of resonant-tunneling nanostructures. Autors: Konstantin S. Grishakov;Vladimir F. Elesin; Appeared in: IEEE Transactions on Electron Devices Publication date: Jul 2017, volume: 64, issue:7, pages: 2963 - 2969 Publisher: IEEE
» Enabling Self-Healing Smart Grid Through Jamming Resilient Local Controller Switching
 Abstract:A key component of a smart grid is its ability to collect useful information from a power grid for enabling control centers to estimate the current states of the power grid. Such information can be delivered to the control centers via wireless or wired networks. It is envisioned that wireless technology will be widely used for local-area communication subsystems in the smart grid (e.g., in distribution networks). However, various attacks with serious impact can be launched in wireless networks such as channel jamming attacks and denial-of-service attacks. In particular, jamming attacks can cause significant damages to power grids, e.g., delayed delivery of time-critical messages can prevent control centers from properly controlling the outputs of generators to match load demands. In this paper, a communication subsystem with enhanced self-healing capability in the presence of jamming is designed via intelligent local controller switching while integrating a retransmission mechanism. The proposed framework allows sufficient readings from smart meters to be continuously collected by various local controllers to estimate the states of a power grid under various attack scenarios. The jamming probability is also analyzed considering the impact of jammer power and shadowing effects. In addition, guidelines on optimal placement of local controllers to ensure effective switching of smart meters under jamming are provided. Via theoretical, experimental and simulation studies, it is demonstrated that our proposed system is effective in maintaining communications between smart meters and local controllers even when multiple jammers are present in the network. Autors: Hongbo Liu;Yingying Chen;Mooi Choo Chuah;Jie Yang;H. Vincent Poor; Appeared in: IEEE Transactions on Dependable and Secure Computing Publication date: Jul 2017, volume: 14, issue:4, pages: 377 - 391 Publisher: IEEE
» Endogenous Probabilistic Reserve Sizing and Allocation in Unit Commitment Models: Cost-Effective, Reliable, and Fast
 Abstract:In power systems with high shares of variable and limitedly predictable renewables, power system operators need to schedule flexible load, generation, and storage to maintain the power system balance when forecast errors occur. To ensure a reliable and cost-effective power system operation, novel reserve sizing and allocation methods are needed. Although stochastic formulations of the unit commitment (UC) problem allow calculating an optimal trade-off between the cost of scheduling and activating reserves, load shedding and curtailment, these models may become computationally intractable for real-life power systems. Therefore, in this paper, we develop a novel set of probabilistic reserve constraints, which allows internalizing the reserve sizing and allocation problem in a deterministic UC model, considering the full cost of reserve allocation and activation. Extensive numerical simulations show that this novel formulation yields UC schedules that are nearly as cost-effective as the theoretical optimal solution of the stochastic model in calculation times similar to that of a deterministic equivalent. Autors: Kenneth Bruninx;Erik Delarue; Appeared in: IEEE Transactions on Power Systems Publication date: Jul 2017, volume: 32, issue:4, pages: 2593 - 2603 Publisher: IEEE
» Energy Driven Avatar Migration in Green Cloudlet Networks
 Abstract:Fully utilizing green energy can remarkably decrease the operational cost of cloudlet providers in provisioning green cloudlet networks (GCNs), which are powered by both green and brown energy. Owing to the spatial and temporal dynamics of energy demands and green energy generation, migrating Avatars (i.e., virtual machines) from green energy deprived cloudlets into green energy over-provisioned cloudlets can reduce the total on-grid energy consumption of GCN. However, Avatar migration itself consumes non-negligible energy consumption. In this letter, we propose the Energy driven AvataR migration (EARN) scheme to reduce the total on-grid energy consumption of GCN by considering the energy consumption of Avatar migrations. The performance of EARN is demonstrated by extensive simulations. Autors: Qiang Fan;Nirwan Ansari;Xiang Sun; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1601 - 1604 Publisher: IEEE
» Energy Efficiency Optimization of Secondary Network Considering Primary User Return With Alternating-Phase-Type Traffic
 Abstract:Much work has been done in the area of cognitive radio networks to formulate the inherent tradeoff among different metrics, such as sensing and throughput. Primary user (PU) traffic behavior can affect the mentioned tradeoff and must be considered in analyses, especially when cognitive users coexist with the dynamic-traffic PU. In this case, PU-returns to the spectrum during secondary users’ (SUs) transmission are more likely and, hence, such kinds of interference are inevitable. Furthermore, how to model the PU traffic is important. Note that there are two kinds of interference between SU and PU in cognitive radio networks, one due to sensing error and the other due to primary user reoccupancy. In this paper, a new metric called energy per successful transmission time is defined to address both kinds of inference by formulating SUs’ successful transmission time as well as energy consumption. Furthermore, collision probability and average packet delay are formulated considering these interference metrics and the primary user traffic is modeled as an alternating phase type renewal process by which many traffic behaviors, such as long range dependency and self-similarity can be modeled. Finally, some numerical examples are given and the corresponding curves for different metrics are discussed. Autors: Mohammad Reza Amini;Mehdi Mahdavi;Mohammad Javad Omidi; Appeared in: IEEE Transactions on Communications Publication date: Jul 2017, volume: 65, issue:7, pages: 3095 - 3109 Publisher: IEEE
» Energy Efficient Clustering Algorithm for Multi-Hop Wireless Sensor Network Using Type-2 Fuzzy Logic
 Abstract:Lifetime enhancement has always been a crucial issue as most of the wireless sensor networks (WSNs) operate in unattended environment where human access and monitoring are practically infeasible. Clustering is one of the most powerful techniques that can arrange the system operation in associated manner to attend the network scalability, minimize energy consumption, and achieve prolonged network lifetime. To conquer this issue, current researchers have triggered the proposition of many numerous clustering algorithms. However, most of the proposed algorithms overburden the cluster head (CH) during cluster formation. To overcome this problem, many researchers have come up with the idea of fuzzy logic (FL), which is applied in WSN for decision making. These algorithms focus on the efficiency of CH, which could be adoptive, flexible, and intelligent enough to distribute the load among the sensor nodes that can enhance the network lifetime. But unfortunately, most of the algorithms use type-1 FL (T1FL) model. In this paper, we propose a clustering algorithm on the basis of interval type-2 FL model, expecting to handle uncertain level decision better than T1FL model. Autors: Padmalaya Nayak;Bhavani Vathasavai; Appeared in: IEEE Sensors Journal Publication date: Jul 2017, volume: 17, issue:14, pages: 4492 - 4499 Publisher: IEEE
» Energy Efficient Coverage Extension Relay Node Placement in LTE-A Networks
 Abstract:Deployed long term evolution-advanced (LTE-A) infrastructure may need coverage extension due to the exponential growth of mobile broadband data usages as well as poor network performance along the cell edges. A proper installation of relay nodes (RN) extends the network coverage in LTE-A networks. We propose an energy efficient and optimal RN placement (EEORNP) algorithm that maximizes the network coverage under the energy constraint, while maintaining the signal-to-interference ratio. The algorithm is based on an improved greedy algorithm, where an effective and optimal RN placement is guaranteed when the matroid rank function of the energy efficient coverage extension optimization is sub-modular and monotonic. The performance is investigated in terms of coverage percentage and number of RN needed to cover users. Results show that the proposed EEORNP outperforms both greedy and random placement algorithms. Autors: Armeline Dembo Mafuta;Tom Walingo;Telex M. N. Ngatched; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1617 - 1620 Publisher: IEEE
» Energy Saving With Network Coding Design Over Rayleigh Fading Channel
 Abstract:In this paper, we investigate the energy minimization problem with and without network coding (NC) while satisfying the transmission rate requirements in a bidirectional cellular relay network, where a group of mobile users communicate with a base station across a relay node. In particular, we consider the Rayleigh fading channel model and adopt a comprehensive power consumption model in the radio frequency transmission. We show that the problem of minimizing the energy consumption of the bidirectional cellular relay network in NC and non-NC (NNC) schemes can be formulated as a unified sum of fractional programming problem, which is of high complexity to solve in general. Fortunately, we derive the sufficient condition under which the problem is a convex optimization problem, and thus can be solved quite efficiently. In the case that the energy minimizing problem is not convex, we decompose it into two subproblems, and propose an iterative algorithm to solve it. Simulation results show that in NNC and NC schemes, under all configurations of power parameters, the performance of the iterative algorithm is close to the exhaustive search method; but its running time is much shorter than the exhaustive search method. Furthermore, compared with the maximum power transmission policy, the iterative algorithm achieves a maximum energy reduction of 75%–82%. Last but not least, we compare the energy performance of NNC and NC schemes and discuss the effect of the iteration number and the relay node placement. Autors: Shijun Lin;Liqun Fu;Yong Li; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4503 - 4518 Publisher: IEEE
» Energy- and Power-Split Management of Dual Energy Storage System for a Three-Wheel Electric Vehicle
 Abstract:Specific applications such as recreational vehicles require new developments with respect to their energy storage system (ESS). Despite some recent trends in battery development, the ratio between power and energy has not yet met the requirements of these specific kinds of vehicles. This paper presents the integration of a SuperCapacitors (SCs) pack in a three-wheel electric vehicle considering the energy- and power-split management strategy. An energy-management strategy based on a comprehensive fuzzy logic controller approach is fully addressed to increase the global efficiency and performance of the studied vehicle. The proposed control and management strategy ensures that the battery supplies the average portion of the power demand, while the energy level of the SCs is smartly handled. The proposed strategy is easily adaptable to other vehicles or different driving modes. The approach was validated with a power-level hardware-in-the-loop (HIL) platform for a reduced-scale hybrid dual ESS. This experimental test allows real-time verification of the proposed energy management and evaluates the ability to coordinate more efficiently the energy flow. The proposed approach enhances the battery lifetime by reducing the battery current root-mean-square (RMS) value by 12% compared to a battery-only architecture. Autors: João Pedro F. Trovão;Marc-André Roux;Éric Ménard;Maxime R. Dubois; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5540 - 5550 Publisher: IEEE
» Energy-Efficient BBU Allocation for Green C-RAN
 Abstract:Cloud radio access network (C-RAN) separates the baseband processing from the radio transmissions in the base station. The baseband processing is done at the baseband unit (BBU), centrally for a huge number of remote radio head (RRH). The BBU pool works virtually and significantly to reduce power consumption in the cellular networks. Efficient coordination among these BBUs can improve network performance in terms of resource utilization and power consumption. In this letter, we propose a BBU and RRH association scheme based on graph partitioning and rejoining to minimize the power consumption due to communication overhead. Simulation results show that the proposed algorithm improves power consumption up to 20% and reduces handover overhead up to 30% compared with the traditional approach. Autors: Bharat J. R. Sahu;Shatarupa Dash;Navrati Saxena;Abhishek Roy; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1637 - 1640 Publisher: IEEE
» Energy-Efficient D2D Overlaying Communications With Spectrum-Power Trading
 Abstract:In this paper, we investigate device-to-device (D2D) overlaying communications with spectrum-power trading, where D2D users (DUs) consume transmit power to relay cell-edge cellular users (CUs) for uplink transmission in exchange for bandwidth from CUs for D2D communications. The proposed spectrum-power trading aims at exploiting individual disparities from both the spectrum and the power perspectives. Recently, energy efficiency (EE) defined by the ratio of the date rate to the power consumption has become increasingly important for devices due to their limited capacity batteries. As such, our goal is to maximize the weighted sum EE (WSEE) of DUs via a joint D2D relay selection, bandwidth allocation, and power allocation while guaranteeing the quality of service of each CU. Specifically, we study WSEE maximization problems for two different cases, i.e., public-interest DUs and self-interest DUs, depending on whether the DUs are willing to share their obtained bandwidth with each other or not. For the case of public-interest DUs, we show that for a given D2D relay selection, the objective function of the WSEE maximization problem in a fractional form can be transformed into a subtractive form that is more tractable based on the fractional programming theory. To perform D2D relay selection, we first reveal a fundamental relationship between the WSEE and two other EE metrics, i.e., system-centric EE and fairness-centric EE, which, to the best of our knowledge, has never been found in the existing works. Based on this insight, the D2D relay selection problem can be cast as a minimum weighted bipartite matching problem. For the case of self-interest DUs, we show that the corresponding problem can also be solved with optimality by the algorithm proposed for the previous case. Simulation results demonstrate the effectiveness of the proposed algorithm. Autors: Qingqing Wu;Geoffrey Ye Li;Wen Chen;Derrick Wing Kwan Ng; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4404 - 4419 Publisher: IEEE
» Energy-Efficient Massive MIMO: Wireless-Powered Communication, Multiuser MIMO with Hybrid Precoding, and Cloud Radio Access Network with Variable-Resolution ADCs
 Abstract:Increasing access to telecommunication services in rural parts of the world has the potential to alleviate the digital divide felt by the people of these regions. Recently, both public and private sector entities have shown more interest in tackling this problem on a global scale. In the United States, for example, the Federal Communications Commission (FCC) subsidizes large telecommunication companies to offer affordable services in unserved areas through the Connect America Fund. Facebook's Internet. org [1] and Google's Project Loon [2] are some examples of large-scale rural connectivity efforts in the private sector. Deployment of connectivity solutions in rural communities, however, faces many practical challenges. Lack of availability and access to reliable electricity sources is one of the major hindrances for rural connectivity, particularly in underdeveloped countries. As such, wireless connectivity solutions for such applications must focus on low-power hardware operations and high energy efficiency (EE). Autors: Ali Yazdan;Jeonghun Park;Sungwoo Park;Talha A. Khan;Robert W. Heath; Appeared in: IEEE Microwave Magazine Publication date: Jul 2017, volume: 18, issue:5, pages: 18 - 30 Publisher: IEEE
» Energy-Efficient Query Processing in Web Search Engines
 Abstract:Web search engines are composed by thousands of query processing nodes, i.e., servers dedicated to process user queries. Such many servers consume a significant amount of energy, mostly accountable to their CPUs, but they are necessary to ensure low latencies, since users expect sub-second response times (e.g., 500 ms). However, users can hardly notice response times that are faster than their expectations. Hence, we propose the Predictive Energy Saving Online Scheduling Algorithm () to select the most appropriate CPU frequency to process a query on a per-core basis. aims at process queries by their deadlines, and leverage high-level scheduling information to reduce the CPU energy consumption of a query processing node. bases its decision on query efficiency predictors, estimating the processing volume and processing time of a query. We experimentally evaluate upon the TREC ClueWeb09B collection and the MSN2006 query log. Results show that can reduce the CPU energy consumption of a query processing node up to 48 percent compared to a system running at maximum CPU core frequency. outperforms also the best state-of-the-art competitor with a 20 percent energy saving, while the competitor requires a fine parameter tuning and it may incurs in uncontrollable latency violations. Autors: Matteo Catena;Nicola Tonellotto; Appeared in: IEEE Transactions on Knowledge and Data Engineering Publication date: Jul 2017, volume: 29, issue:7, pages: 1412 - 1425 Publisher: IEEE
» Energy-Efficient Traffic Splitting for Time-Varying Multi-RAT Wireless Networks
 Abstract:This paper investigates the energy-efficient traffic splitting for time-varying wireless networks, which have been configured with multiple radio access technologies (multi-RATs). A single stream of the media content is split into multiple segments, which could be transmitted over multiple RATs simultaneously so that the complementary advantages of different RATs can be exploited. To address this problem, we formulate the traffic splitting as a long-term energy efficiency (EE) maximization problem with respect to the time-varying channel state information (CSI). An equivalent transformation method is proposed to convert the long-term nonconvex EE maximization problem into a concave optimization. To reduce the computational complexity, we develop a dynamic traffic splitting (DTS) algorithm, which iterates only one time when the network state changes. Then, we use the definition of tracking error to describe the difference between the DTS and the target optimal traffic splitting solution. After that, an adaptive-compensation traffic splitting (ACTS) algorithm is proposed to offset the tracking error so as to enhance the EE performance. More specifically, we give a sufficient condition for significantly eliminating the tracking errors of the ACTS algorithm. Simulation results show that the proposed ACTS algorithm obtains the EE performance comparable with the optimal solution at the overhead of only a single iteration at each timeslot of the network state acquisition. Autors: Weihua Wu;Qinghai Yang;Peng Gong;Kyung Sup Kwak; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6523 - 6535 Publisher: IEEE
» Engagement and Popularity Dynamics of YouTube Videos and Sensitivity to Meta-Data
 Abstract:YouTube, with millions of content creators, has become the preferred destination for viewing videos online. Through the Partner program, YouTube allows content creators to monetize their popular videos. Of significant importance for content creators is which meta-level features (title, tag, thumbnail, and description) are most sensitive for promoting video popularity. The popularity of videos also depends on the social dynamics, i.e., the interaction of the content creators (or channels) with YouTube users. Using real-world data consisting of about 6 million videos spread over 25 thousand channels, we empirically examine the sensitivity of YouTube meta-level features and social dynamics. The key meta-level features that impact the view counts of a video include: first day view count, number of subscribers, contrast of the video thumbnail, Google hits, number of keywords, video category, title length, and number of upper-case letters in the title, respectively, and illustrate that these meta-level features can be used to estimate the popularity of a video. In addition, optimizing the meta-level features after a video is posted increases the popularity of videos. In the context of social dynamics, we discover that there is a causal relationship between views to a channel and the associated number of subscribers. Additionally, insights into the effects of scheduling and video playthrough in a channel are also provided. Our findings provide a useful understanding of user engagement in YouTube. Autors: William Hoiles;Anup Aprem;Vikram Krishnamurthy; Appeared in: IEEE Transactions on Knowledge and Data Engineering Publication date: Jul 2017, volume: 29, issue:7, pages: 1426 - 1437 Publisher: IEEE
» Enhanced Analog Beamforming for Single Carrier Millimeter Wave MIMO Systems
 Abstract:Analog beamforming has been considered an attractive technology for future single carrier millimeter-wave multiple-input multiple-output (MIMO) systems because of the high cost and huge power consumption of mixed-signal devices. Most conventional studies have focused on joint base station and user equipment (BS-UE) analog beamforming with the objective of improving the average signal to noise ratio performance before the baseband equalization. In contrast, this paper aims to optimize the BS-UE analog beamforming vectors in the sense of minimizing the mean square error of the baseband equalized signal. Considering practical implementation requirement, we combine the gradient descent (GD) method and the iterative antenna training (IAT) technique, and propose an iterative local GD (ILGD) algorithm. We analyze the convergence property, bit error rate (BER) performance, training overhead, and computational complexity of the ILGD algorithm. Simulation results show that the proposed ILGD algorithm can achieve a gain of more than 2 dB at a BER of over the conventional IAT algorithm with the same training overhead. Autors: Xianchi Li;Yu Zhu;Pengfei Xia; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4261 - 4274 Publisher: IEEE
» Enhanced Electrical Performance and Stability in Zinc Oxynitride Thin-Film Transistors via Sequential Ultraviolet and Thermal Treatment
 Abstract:In this letter, the sequential combination of ultraviolet (UV) irradiation and thermal annealing is proposed as an effective post-deposition treatment method to improve the electrical performance and stability in high-mobility zinc oxynitride (ZnON) thin-film transistors (TFTs). The results indicated that the sequential combination of UV irradiation and thermal annealing at 270 °C more effectively increased the field-effect mobility of the TFT and improved the electrical stability of the device under positive gate-bias stresses when compared with other post-deposition treatment methods of UV irradiation, thermal annealing at 270 °C, and thermal annealing at 350 °C. A decrease in the number of the defective ZnXNY bonds and an increase in that of the stoichiometric Zn3N2 bonds were clearly observed when the ZnON thin-film was post-treated by the sequential combination of UV irradiation and thermal annealing at 270 °C. A decrease in the defective ZnXNY bond-related subgap states is considered as the dominant mechanism responsible for the enhanced electrical properties of the UV-after thermally treated ZnON TFTs. Autors: Hwan-Seok Jeong;Dae-Hwan Kim;Hyuck-In Kwon; Appeared in: IEEE Electron Device Letters Publication date: Jul 2017, volume: 38, issue:7, pages: 883 - 886 Publisher: IEEE
» Enhanced Light Extraction From DUV-LEDs by AlN-Doped Fluoropolymer Encapsulation
 Abstract:AlN-doped fluoropolymer encapsulation layer was proposed for deep-ultraviolet light-emitting diodes. The proposed method can significantly enhance the light extraction from the chip-on-board packaging structure, which is attributed to the increased refractive index and light scattering ability of the encapsulant layer by the doping of AlN nanoparticles (NPs). When the AlN NPs content increases from 0.05 to 0.15 wt%, the light output power enhancement increases from 10.1% to 16.4% at a driving current of 120 mA compared with pure fluoropolymer packaging structure. Furthermore, after aging tests at 100 °C for 600 h, the relative light output power of the 0.15 wt% AlN-doped fluoropolymer structure is only reduced by 5.3%, which is much lower than the pure fluoropolymer structure of 13% and the conventional silicone structure of 23.2%. Autors: Yang Peng;Xin Guo;Renli Liang;Hao Cheng;Mingxiang Chen; Appeared in: IEEE Photonics Technology Letters Publication date: Jul 2017, volume: 29, issue:14, pages: 1151 - 1154 Publisher: IEEE
» Enhanced Orthogonal Frequency Division Multiplexing With Index Modulation
 Abstract:Index modulation concept has attracted considerable research interest in the past few years. As a realization of index modulation in the frequency domain, orthogonal frequency division multiplexing with index modulation (OFDM-IM) has recently been proposed, which conveys information bits through both the subcarrier activation patterns and the amplitude phase modulation constellation points. This paper proposes two enhanced OFDM-IM schemes aimed at achieving higher spectral efficiency and diversity gain, respectively. The first one, termed OFDM with hybrid in-phase/quadrature index modulation (OFDM-HIQ-IM), explores the I- and Q- dimensions jointly for index modulation, allowing transmission of more index modulation bits in each subcarrier group. The second one, termed linear constellation precoded OFDM-IQ-IM (LP-OFDM-IQ-IM), spreads information symbols across two adjacent active subcarriers through linear constellation precoding to harvest additional diversity gain. By maximizing the minimum squared Euclidean distance, two different realizations of LP-OFDM-IQ-IM are derived, which leads to a rotated and a diamond-shaped constellation, respectively. The proposed OFDM-HIQ-IM and LP-OFDM-IQ-IM, as revealed by both theoretical analyses and computer simulations, enable low-complexity detection and exhibit superior error rate performance over the existing OFDM-IM schemes. Autors: Miaowen Wen;Binbin Ye;Ertugrul Basar;Qiang Li;Fei Ji; Appeared in: IEEE Transactions on Wireless Communications Publication date: Jul 2017, volume: 16, issue:7, pages: 4786 - 4801 Publisher: IEEE
» Enhanced Power Flow Control for Grid-Connected Droop-Controlled Inverters With Improved Stability
 Abstract:Droop control strategy is widely applied in ac microgrid to realize the seamless mode transition and achieve average power sharing among different inverters. However, there is a lack of analysis about the operation performance of droop control strategy in grid-connected mode. In this paper, grid fluctuation and control accuracy of reactive power are illustrated to be the main influence factors for power flow control according to the small-signal model. The feedforward of grid frequency and voltage magnitude is proposed to mitigate the impacts of grid fluctuation on power flow control. Since the feedforward items are achieved through the synchronous reference frame phase-locked loop with the input of filter capacitor voltage, extra sensors for grid voltage are avoided. Moreover, voltage magnitude control is introduced to enhance the control accuracy of reactive power flow. In addition, modified droop control loops are also proposed to improve the system stability. With the implementation of the proposed control scheme, improved power flow control and enhanced system stability are achieved with the feature of seamless mode transition maintained. Finally, the major contribution of this paper is verified by a laboratory prototype. Autors: Yan Deng;Yong Tao;Guipeng Chen;Guangdi Li;Xiangning He; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Jul 2017, volume: 64, issue:7, pages: 5919 - 5929 Publisher: IEEE
» Enhanced Resolution Stripmap Mode Using Dynamic Metasurface Antennas
 Abstract:To maintain sufficient signal-to-noise ratio (SNR) for image reconstruction and image interpretation, conventional synthetic aperture radar (SAR) systems must trade off resolution and scene size. This paper proposes a new SAR mode of operation, which improves resolution while maintaining good SNR and a large scene size. It leverages the unique properties of dynamic metasurface antennas (MSAs) to subsample a large virtual beamwidth utilizing multiple small distinct antenna beams. Due to this parallelization in scene sampling, the constraints on the azimuth sampling rate can be relaxed while maintaining an aliasing-free cross range. Due to the versatile properties of MSAs and their cost effective manufacturing process, this paper proposes SAR systems, which can obtain high resolution images over a wide scene size with lower cost and complexity than competing approaches. Point-spread functions and proof-of-concept SAR simulations are shown to verify this approach. In addition, laboratory experiments using a commercial prototype MSA are presented, which show an improvement of 62% in cross-range resolution of the proposed approach, compared with the cross-range resolution of stripmap mode SAR with the same aperture. Autors: Andreas Pedross-Engel;Claire M. Watts;David R. Smith;Matthew S. Reynolds; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Jul 2017, volume: 55, issue:7, pages: 3764 - 3772 Publisher: IEEE
» Enhancing Binary Classification by Modeling Uncertain Boundary in Three-Way Decisions
 Abstract:Text classification is a process of classifying documents into predefined categories through different classifiers learned from labelled or unlabelled training samples. Many researchers who work on binary text classification attempt to find a more effective way to separate relevant texts from a large data set. However, current text classifiers cannot unambiguously describe the decision boundary between positive and negative objects because of uncertainties caused by text feature selection and the knowledge learning process. This paper proposes a three-way decision model for dealing with the uncertain boundary to improve the binary text classification performance based on the rough set techniques and centroid solution. It aims to understand the uncertain boundary through partitioning the training samples into three regions (the positive, boundary and negative regions) by two main boundary vectors C~P and C~N, created from the labeled positive and negative training subsets, respectively, and further resolve the objects in the boundary region by two derived boundary vectors B~P and B~N, produced according to the structure of the boundary region. It involves an indirect strategy which is composed of two successive steps in the whole classification process: ‘two-way to three-way’ and ‘three-way to two-way’. Four decision rules are proposed from the training process and applied to the incoming documents for more precise classification. A large number of experiments have been conducted based on the standard data sets RCV1 and Reuters-21578. The experimental results show that the usage of boundary vectors is very effective and efficient for dealing with uncertainties of the decision boundary, and the proposed model has significantly improved the performance of binary text classification in terms of F1 measure and AUC area compared with six other popular baseline models. Autors: Yuefeng Li;Libiao Zhang;Yue Xu;Yiyu Yao;Raymond Yiu Keung Lau;Yutong Wu; Appeared in: IEEE Transactions on Knowledge and Data Engineering Publication date: Jul 2017, volume: 29, issue:7, pages: 1438 - 1451 Publisher: IEEE
» Envelope-Function-Based Transport Simulation of a Graphene Ribbon With an Antidot Lattice
 Abstract:We have performed numerical simulations to study the effect of a regular lattice of antidots on the conductance, and in particular on the gap, of an armchair graphene ribbon. We have used an envelope-function approach, with a nonzero mass term mimicking the presence of the antidots. With a very efficient simulation procedure, consisting in a reciprocal space solution of the envelope-function equation in the transverse direction followed by a recursive scattering matrix calculation in the transport direction, we have been able to analyze the impact of the different geometrical parameters characterizing the structure. We have observed that the conductance of the device rapidly reaches an asymptotic value when the length of the region containing the antidot lattice is increased. The dependence of the energy gap on the geometrical features of the antidot lattice is quite similar to that observed in unconfined graphene, excluding the cases of very small or distant antidots, for which the energy gap of the pristine graphene ribbons is recovered. The tilt angle of the lattice with respect to the transport direction has a negligible influence on the gap, which is also quite robust with respect to the introduction of disorder in the antidot lattice. Autors: Paolo Marconcini;Massimo Macucci; Appeared in: IEEE Transactions on Nanotechnology Publication date: Jul 2017, volume: 16, issue:4, pages: 534 - 544 Publisher: IEEE
» Equipment Monitoring Using Thermography Cameras: Remote Detection of Temperature-Related Failures
 Abstract:Protecting critical infrastructure such as electricity, oil, and gas to prevent catastrophic failure is imperative to maintain the functioning of today’s technological world. The U.S. government is putting into place programs such as the North American Electric Reliability Corporation [12] and the Federal Energy Regulatory Commission [13] to ensure that monitoring solutions exist for these critical infrastructures. Our proposed solution is to use a thermography camera on critical systems, which can provide 24/7 monitoring and thus offer insight into equipment performance over time. Autors: Yu-Wei Alan Wang;Terence Hazel;Ronny Hjornevik;Oyvind Fjeld; Appeared in: IEEE Industry Applications Magazine Publication date: Jul 2017, volume: 23, issue:4, pages: 35 - 44 Publisher: IEEE
» Equipment Testing Safety [Electrical Safety]
 Abstract:Examines the tasks that are part of equipment testing and reports on the hazards workers face. These tasks are done during many phases of work in an industrial setting, including quality assurance (QA) tests when receiving new equipment for a project, commissioning checks during installation and turnover to the process owner, mechanical integrity (MI) checks on a regular basis during normal operations, and equipment troubleshooting when problems arise. During all these types of testing, we face a higher risk of encountering exposed energized conductors and circuits. Workers may need to connect testing devices to the equipment and will often need to open doors or covers. Testing devices can have a power supply or separate source of power that can put voltage on locked out equipment. There may be stored power in the equipment, such as capacitor banks, that can be a shock hazard. Presents a look at each of these typical phases of testing and the electrical hazards that may be unique to them. Autors: Daniel Doan; Appeared in: IEEE Industry Applications Magazine Publication date: Jul 2017, volume: 23, issue:4, pages: 6 - 7 Publisher: IEEE
» Equivalence for Networks With Adversarial State
 Abstract:We address the problem of finding the capacity of noisy networks with either independent point-to-point compound channels (CC) or arbitrarily varying channels (AVC). These channels model the presence of a Byzantine adversary, which controls a subset of links or nodes in the network. We derive equivalence results showing that these point-to-point channels with state can be replaced by noiseless bit-pipes without changing the network capacity region. Exact equivalence results are found for the CC model, and for some instances of the AVC, including all nonsymmetrizable AVCs. These results show that a feedback path between the output and input of a CC can increase the equivalent capacity, and that if common randomness can be established between the terminals of an AVC (either by a feedback, a forward path, or via a third-party node), then again the equivalent capacity can increase. This leads to an observation that deleting an edge of arbitrarily small capacity can cause a significant change in network capacity. We also analyze an example involving an AVC for which no fixed-capacity bit-pipe is equivalent. Autors: Oliver Kosut;Jörg Kliewer; Appeared in: IEEE Transactions on Information Theory Publication date: Jul 2017, volume: 63, issue:7, pages: 4137 - 4154 Publisher: IEEE
» Equivalent Magnetic Noise in Magnetoelectric Laminates Comprising Bidomain LiNbO3 Crystals
 Abstract:The anisotropic direct magnetoelectric (ME) properties of bilayered composites comprising magnetostrictive metglas foils and single-crystalline piezoelectric bidomain plates of 127°Y-cut LiNbO3 (LNO) have been studied theoretically and experimentally. The LNO plates possessed an engineered ferroelectric macrobidomain structure with opposite spontaneous polarization vectors. Impedance, ME effect, and equivalent magnetic noise density (EMND) measurements have been performed under quasi-static and resonant conditions. Whereas the quasi-static ME effect was only two times stronger in the bidomain samples compared to their unidomain and bonded bimorph counterparts, in the bending resonance mode, the effect was up to one order of magnitude stronger: ME coefficients of up to 578 V/() were obtained at ca. 30 kHz under resonance using 0.5-mm-thick crystals. EMND measurements yielded values down to 153 pT/Hz at 1 kHz and 524 fT/Hz under resonant conditions. A further optimization of the fabrication techniques, laminate geometry, and detection circuit is expected to allow reducing these values down to at least 10 pT/Hz and 250 fT/Hz, respectively, and the resonance frequency by at least two orders of magnitude. Such systems may thus find use in simple and sensitive, passive and stable, low frequency and high-temperature vector magnetic field sensors. Autors: João V. Vidal;Andrei V. Turutin;Ilya V. Kubasov;Mikhail D. Malinkovich;Yurii N. Parkhomenko;Svetlana P. Kobeleva;Andrei L. Kholkin;Nikolai A. Sobolev; Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control Publication date: Jul 2017, volume: 64, issue:7, pages: 1102 - 1119 Publisher: IEEE
» Erasing-Modes Dependent Performance of a-IGZO TFT Memory With Atomic-Layer-Deposited Ni Nanocrystal Charge Storage Layer
 Abstract:Amorphous indium–gallium–zinc–oxide (a-IGZO) thin-film transistor (TFT) memory devices are fabricated with plasma-assisted atomic-layer-deposition (ALD) charge storage medium of high-density Ni nanocrystals (NCs). The effect of Al2O3 tunneling layer thickness (i.e., 8 and 12 nm) on the memory characteristics is investigated. The results indicate that the 8-nm tunneling layer device shows a programming window as large as 4.7 V after 5-ms programming at 18 V, reflecting that the ALD Ni NCs have a high charge storage capacity. To achieve a high erasing efficiency, different erasing modes are explored, including electrical erasing, monochromatic light (ML) erasing, and ML-assisted electrical erasing. It is demonstrated that the ML-assisted electrical erasing can attain the highest erasing efficiency, e.g., an erasing window as large as 9.11 V is obtained after 100-s ML (300 nm)-assisted electrical erasing at −20 V for the 8-nm tunneling layer. Based on the above programming and erasing conditions, the ten-year memory window is extrapolated to be 4.7 V at room temperature. Though increasing the tunneling layer thickness may enhance the data retention, it also degrades the programming and erasing efficiencies slightly. Autors: Shi-Bing Qian;Yan Shao;Wen-Jun Liu;David Wei Zhang;Shi-Jin Ding; Appeared in: IEEE Transactions on Electron Devices Publication date: Jul 2017, volume: 64, issue:7, pages: 3023 - 3027 Publisher: IEEE
» Error Correction Coding Meets Cyber-Physical Systems: Message-Passing Analysis of Self-Healing Interdependent Networks
 Abstract:Coupling cyber and physical systems gives rise to numerous engineering challenges and opportunities. An important challenge is the contagion of failure from one system to another, which can lead to large-scale cascading failures. However, the self-healing ability emerges as a valuable opportunity where the overlaying cyber network can cure failures in the underlying physical network. To capture both self-healing and contagion, this paper considers a graphical model representation of an interdependent cyber-physical system, in which nodes represent various cyber or physical functionalities, and edges capture the interactions between the nodes. A message-passing algorithm is proposed for this representation to study the dynamics of failure propagation and healing. By conducting a density evolution analysis for this algorithm, network reaction to initial disruptions is investigated. It is proved that as the number of message-passing iterations increases, the network reaches a steady-state condition that would be either a complete healing or a complete collapse. Then, a sufficient condition is derived to select the network parameters to guarantee the complete healing of the system. The result of the density evolution analysis is further employed to jointly optimize the design of cyber and physical networks for maximum resiliency. This analytical framework is then extended to the cases where the propagation of failures in the physical network is faster than the healing responses of the cyber network. Such scenarios are of interest in many real-life applications such as smart grid. Finally, extensive numerical results are presented to verify the analysis and investigate the impact of the network parameters on the resiliency of the network. Autors: Ali Behfarnia;Ali Eslami; Appeared in: IEEE Transactions on Communications Publication date: Jul 2017, volume: 65, issue:7, pages: 2753 - 2768 Publisher: IEEE
» Error-Corrected Reflection and Transmission Scattering Parameters of a Two-Port Device
 Abstract:We present an error correction algorithm for extraction of reflection and transmission scattering (S-) parameters of a two-port device without resorting to a complete two-port calibration. It is shown that S-parameters of thru and nonreflecting line connections in addition to S-parameters of an unknown device (and its reversed orientation) are needed for extracting full S-parameters of the device. For validation, we performed simulations for a chiral metamaterial (transmission asymmetric) and carried out measurements of S-parameters of an asymmetrically loaded waveguide section (reflection asymmetric). Autors: Ugur C. Hasar;Musa Bute; Appeared in: IEEE Microwave and Wireless Components Letters Publication date: Jul 2017, volume: 27, issue:7, pages: 681 - 683 Publisher: IEEE
» Estimating Heart Rate and Rhythm via 3D Motion Tracking in Depth Video
 Abstract:Low-cost depth sensors, such as Microsoft Kinect, have potential for noncontact health monitoring that is robust to ambient lighting conditions. However, captured depth images typically suffer from high acquisition noise, and hence, processing them to estimate biometrics is difficult. In this paper, we propose to capture depth video of a human subject using Kinect 2.0 to estimate his/her heart rate and rhythm; as blood is pumped from the heart to circulate through the head, tiny oscillatory head motion due to Newtonian mechanics can be detected for periodicity analysis. Specifically, we first restore a captured depth video via a joint bit-depth enhancement/denoising procedure, using a graph-signal smoothness prior for regularization. Second, we track an automatically detected head region throughout the depth video to deduce 3D motion vectors. The detected vectors are fed back to the depth restoration module in a loop to ensure that the motion information in two modules is consistent, improving performance of both restoration and motion tracking. Third, the computed 3D motion vectors are projected onto its principal component for 1D signal analysis, composed of trend removal, bandpass filtering, and wavelet-based motion denoising. Finally, the heart rate is estimated via Welch power spectrum analysis, and the heart rhythm is computed via peak detection. Experimental results show accurate estimation of the heart rate and rhythm using our proposed algorithm as compared to rate and rhythm estimated by a portable oximeter. Autors: Cheng Yang;Gene Cheung;Vladimir Stankovic; Appeared in: IEEE Transactions on Multimedia Publication date: Jul 2017, volume: 19, issue:7, pages: 1625 - 1636 Publisher: IEEE
» Estimating Top-of-Atmosphere Daily Reflected Shortwave Radiation Flux Over Land From MODIS Data
 Abstract:High-spatial resolution data of the top-of-atmosphere (TOA) reflected shortwave radiation flux are needed to understand the effects of local-scale anthropogenic and natural processes on earth’s radiation budget. A previous study developed an algorithm to estimate the TOA instantaneous shortwave component from polar-orbiting Moderate Resolution Imaging Spectroradiometer (MODIS) data. This paper presents a temporal scaling approach to predict daily values of TOA reflected shortwave radiation flux from temporally sparse MODIS observations. Radiative transfer simulation and statistical regression are used to establish the relationship between daily shortwave flux and MODIS spectral reflectance. A comparison between the Terra and Aqua combined MODIS computed data and the Clouds and the Earth’s Radiant Energy System SYN1deg product of 1° regional daily shortwave fluxes have a bias of 3.8 W/ with a root-mean-square error (RMSE) of 13.3 W/ using data from 2009 over eight subsets across various latitudes. Comparing the regional monthly shortwave fluxes reduces the RMSE to 6.9 W/. The longer the averaging period the lower the uncertainty is self-explanatory. Autors: Dongdong Wang;Shunlin Liang; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Jul 2017, volume: 55, issue:7, pages: 4022 - 4031 Publisher: IEEE
» Estimation of Boreal Forest Properties From TanDEM-X Data Using Inversion of the Interferometric Water Cloud Model
 Abstract:In this letter, the interferometric water cloud model (IWCM) is fit to 87 VV-polarized TanDEM-X acquisitions made between June 2011 and August 2014 over a boreal forest in Krycklan, northern Sweden, using a new method based on nonlinear least-squares optimization. A high-resolution digital terrain model is used as ground reference during interferometric synthetic-aperture radar (InSAR) processing and 26 stands with areas 1.5–22 ha and unaltered during the study period are studied. The dependence of biomass estimation performance, ground and vegetation backscatter coefficients ( and ), canopy attenuation (), and zero-biomass coherence () on selected system and environmental parameters is studied. High correlation between the estimated biomass and reference biomass derived from in situ measurements is observed for all 87 acquisitions ( between 0.81 and 0.93), while the root-mean-square difference is between 18% and 32% for all 43 acquisitions made in snow-free conditions and with heights-of-ambiguity (HOAs) between 36 and 150 m. Significant biomass estimation bias is observed for HOAs above 150 m and for some acquisitions over snow-covered forest. It is also observed that and are the largest for temperatures below 0 °C and with- significant snow cover. For temperatures above 0 °C, appears independent of temperature, while shows a tendency to increase with temperature. Moreover, decreases from just below 1 for HOAs around 40 m to around 0.8 for HOAs above 150 m. Autors: Maciej J. Soja;Jan I. H. Askne;Lars M. H. Ulander; Appeared in: IEEE Geoscience and Remote Sensing Letters Publication date: Jul 2017, volume: 14, issue:7, pages: 997 - 1001 Publisher: IEEE
» Estimation of Frequency Dispersive Complex Permittivity Seen by Each Antenna for Enhanced Multistatic Radar Medical Imaging
 Abstract:Radar-based microwave imaging requires the effective dielectric properties of the imaged object as a priori information. A technique to determine the effective complex permittivity seen by each imaging antenna across the used frequency band of a multistatic imaging domain is presented. The method uses spatial statistical techniques to model the complex permittivity of the imaging domain as a function of scattering parameters. The proposed method does not require any predefined gap between the antennas and the imaged object, nor does it need the imaged object to be centered within the imaging domain. Also, the method does not need to know boundaries of the imaged object. The proposed method is tested via simulations and experiments using a multistatic human torso imaging system. The collected data across the band 0.65–1.75 GHz using twelve antennas around the human torso are processed to generate accurate images. The results demonstrate significant improvements in image quality and detection accuracy compared to conventional average-permittivity methods. The efficacy of the proposed method is verified experimentally in detecting an early case of lung cancer in a human torso phantom. Autors: Ali Zamani;Amin M. Abbosh; Appeared in: IEEE Transactions on Antennas and Propagation Publication date: Jul 2017, volume: 65, issue:7, pages: 3702 - 3711 Publisher: IEEE
» Estimation of Pulse Transit Time as a Function of Blood Pressure Using a Nonlinear Arterial Tube-Load Model
 Abstract:Objective: pulse transit time (PTT) varies with blood pressure (BP) throughout the cardiac cycle, yet, because of wave reflection, only one PTT value at the diastolic BP level is conventionally estimated from proximal and distal BP waveforms. The objective was to establish a technique to estimate multiple PTT values at different BP levels in the cardiac cycle. Methods: a technique was developed for estimating PTT as a function of BP (to indicate the PTT value for every BP level) from proximal and distal BP waveforms. First, a mathematical transformation from one waveform to the other is defined in terms of the parameters of a nonlinear arterial tube-load model accounting for BP-dependent arterial compliance and wave reflection. Then, the parameters are estimated by optimally fitting the waveforms to each other via the model-based transformation. Finally, PTT as a function of BP is specified by the parameters. The technique was assessed in animals and patients in several ways including the ability of its estimated PTT-BP function to serve as a subject-specific curve for calibrating PTT to BP. Results: the calibration curve derived by the technique during a baseline period yielded bias and precision errors in mean BP of 5.1 ± 0.9 and 6.6 ± 1.0 mmHg, respectively, during hemodynamic interventions that varied mean BP widely. Conclusion: the new technique may permit, for the first time, estimation of PTT values throughout the cardiac cycle from proximal and distal waveforms. Significance: the technique could potentially be applied to improve arterial stiffness monitoring and help realize cuff-less BP monitoring. Autors: Mingwu Gao;Hao-Min Cheng;Shih-Hsien Sung;Chen-Huan Chen;Nicholas Bari Olivier;Ramakrishna Mukkamala; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Jul 2017, volume: 64, issue:7, pages: 1524 - 1534 Publisher: IEEE
» Estimation of Synchromesh Frictional Torque and Output Torque in a Clutchless Automated Manual Transmission of a Parallel Hybrid Electric Vehicle
 Abstract:This paper studies the estimation of the synchromesh frictional torque and the output torque of the integrated system of an electric motor and a clutchless automated manual transmission (AMT) as part of a two-shaft parallel hybrid electric vehicle powertrain. The case study powertrain is discussed, and the dynamical model of the powertrain from the electric motor to the AMT output shaft, where it is linked to the torque coupler, is developed constituting the basis for the observer design. Given the fact that the aforementioned torques are unknown inputs to the system, they are modeled as state variables of a fictitious unforced linear time-invariant system in order to be aggregated into the systems dynamics. For the augmented system of the actual and fictitious states, a deterministic Luenberger observer and a stochastic Kalman–Bucy filter (KBF) are designed to estimate the synchromesh frictional torque and the output torque of the AMT. The estimation is based on measuring angular velocities of the electric motor and the AMT output shaft, together with the imparted electromagnetic torque of the traction motor on the system. A set of experiments with distinct scenarios is performed to compare the performance of the designed observers and to quantify by how much the KBF can improve the root-mean-square error (RMSE) of the estimation by mitigating the effect of the process and measurement noises. Ultimately, after validation of the designed observers, the estimated value of the synchromesh frictional torque is exploited in a closed-loop feedback configuration in order to track desired trajectories such as step, ramp, and sinusoidal torque commands. Autors: Mir Saman Rahimi Mousavi;Hossein Vahid Alizadeh;Benoit Boulet; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 5531 - 5539 Publisher: IEEE
» Evaluating the Impact of User Behavior on D2D Communications in Millimeter-Wave Small Cells
 Abstract:Small cells in millimeter-wave (mmWave) band are able to provide multigigabit access data rates and have emerged as a cost-efficient solution to offer interference-free device-to-device (D2D) communications. In order to improve system performances and enhance user experiences, direct transmissions between devices need to be scheduled properly. We first propose a transmission scheduling scheme for radio access of small cells in the mmWave band, termed directional D2D medium access control (D3MAC), whereby a path-selection criterion is designed to enable D2D transmissions. Through extensive simulations, we demonstrate that D3MAC achieves near-optimal performances and outperforms other schemes significantly in terms of delay and throughput. Based on this near-optimal scheme, we then evaluate the impact of user behaviors, including the traffic mode and traffic load, as well as user density, denseness, and mobility, on the performance of D2D communications in mmWave small cells. Our study reveals that the performance of D2D communications is improved, as the user density and denseness increase, but this effect is only obvious under heavy traffic loads. Furthermore, user mobility is shown to be another important factor that influences the performance of D2D communications. The system performance is first improved, as the average user speed increases from static, but the performance is degraded significantly when the user speed becomes high. Autors: Chuhan Gao;Yong Li;Haohao Fu;Yong Niu;Depeng Jin;Sheng Chen;Han Zhu; Appeared in: IEEE Transactions on Vehicular Technology Publication date: Jul 2017, volume: 66, issue:7, pages: 6362 - 6377 Publisher: IEEE
» Evaluation of Direct Signal Suppression for Passive Radar
 Abstract:Passive radar (PR) systems must be able to detect the presence of a target signal many orders of magnitude weaker than the direct signal interference (DSI). Due to the continuous nature of most PR signals, this interference, rather than thermal noise, determines the sensitivity of the system. Suppression of DSI and clutter prior to range-Doppler processing is crucial for maximizing the effective dynamic range, to increase detection range and improve overall system performance. A number of time-domain adaptive filtering techniques have been proposed to mitigate the effects of DSI, with varying levels of success. As such, an investigation of the primary factors affecting suppression performance is presented, using Advanced Television Systems Committee digital television (DTV) waveforms as an example, through simulation and extensive experimental trials. A number of spectral and spatially diverse DTV signals are considered to analyze suppression performance under a wide range of realistic scenarios. In particular, the fast block least mean squares filter is shown to provide good suppression performance with low computational requirements. Results of this analysis can be used to predict PR performance and stability. Practical metrics, such as suppression runtime and ease of implementation, also serve to counsel selection of DSI mitigation algorithms for experimental systems. Autors: Joseph Landon Garry;Chris J. Baker;Graeme E. Smith; Appeared in: IEEE Transactions on Geoscience and Remote Sensing Publication date: Jul 2017, volume: 55, issue:7, pages: 3786 - 3799 Publisher: IEEE
» Evaluation of Mobile Phone Performance for Near-Infrared Fluorescence Imaging
 Abstract:We have investigated the potential for contrast-enhanced near-infrared fluorescence imaging of tissue on a mobile phone platform. Charge-coupled device- and phone-based cameras were used to image molded and three-dimensional-printed tissue phantoms, and an ex vivo animal model. Quantitative and qualitative evaluations of image quality demonstrate the viability of this approach and elucidate variations in performance due to wavelength, pixel color, and image processing. Autors: Pejhman Ghassemi;Bohan Wang;Jianting Wang;Quanzeng Wang;Yu Chen;T. Joshua Pfefer; Appeared in: IEEE Transactions on Biomedical Engineering Publication date: Jul 2017, volume: 64, issue:7, pages: 1650 - 1653 Publisher: IEEE
» Evaluation of Outage Probability for Satellite Systems Exploiting Smart Gateway Configurations
 Abstract:In this letter, the authors present an analytical formulation to evaluate the outage probability of a satellite communication system at an extremely high-frequency band when a macro site diversity scheme is employed to mitigate propagation impairments. In particular, the authors generalize the results for smart gateway diversity configurations, supporting the outage of more than one single gateway station. It was verified that the proposed analytical model has good agreement with numerical results. Autors: Tommaso Rossi;Mauro De Sanctis;Fabio Maggio; Appeared in: IEEE Communications Letters Publication date: Jul 2017, volume: 21, issue:7, pages: 1541 - 1544 Publisher: IEEE
» Evaluation of Virtual Synchronous Machines With Dynamic or Quasi-Stationary Machine Models
 Abstract:This paper presents a comparison of the small-signal stability properties for virtual synchronous machines (VSMs) with dynamic and quasi-stationary representation of the internal synchronous machine (SM) model. It is shown that the dynamic electrical equations may introduce poorly damped oscillations when realistic stator impedance values for high-power SMs are used. The quasi-stationary implementation is less sensitive to the impedance of the virtual machine model, but depends on filtering of the measured d- and q-axes components of the ac-side voltage to avoid instability or poorly damped oscillations. It is demonstrated how both implementations can be made stable and robust for a wide range of grid impedances. However, the dynamic electrical model depends on a high virtual resistance for effectively damping internal oscillations associated with dc components in the ac currents during transients. Thus, when using SM parameters with low virtual stator resistance for decoupling the active and reactive power control, the quasi-stationary VSM implementation is preferable. Autors: Olve Mo;Salvatore D'Arco;Jon Are Suul; Appeared in: IEEE Transactions on Industrial Electronics Publication date: Jul 2017, volume: 64, issue:7, pages: 5952 - 5962 Publisher: IEEE
» Evanescently Coupled Waveguide InGaAs UTC-PD Having an Over 21 GHz Bandwidth Under Zero Bias
 Abstract:The design and fabrication of an evanescently coupled waveguide InGaAs unitraveling-carrier photodiode (PD) are presented. Through doping the InGaAs absorption layer gradedly, a large built-in electric field can be obtained. As a result, a 4--wide 15--long PD has a bandwidth larger than 21 GHz at zero bias. Passive input waveguide is integrated monolithically with the PD by a simple process, which eases the integration of PD with other optical components. Autors: Siwei Sun;Song Liang;Junjie Xu;Limeng Zhang;Lu Guo;Xiao Xie;Hongliang Zhu;Wei Wang; Appeared in: IEEE Photonics Technology Letters Publication date: Jul 2017, volume: 29, issue:14, pages: 1155 - 1158 Publisher: IEEE
» Event-Based State Estimation of Hidden Markov Models Through a Gilbert–Elliott Channel
 Abstract:In this note, the problem of event-based state estimation for a finite-state hidden Markov model under a generic stochastic event-triggering condition and an unreliable communication channel is investigated. The effect of packet dropout is characterized with a Gilbert–Elliott process. Utilizing the change of probability measure approach, the packet dropout model and the event-triggered measurement information available to the estimator, analytical expressions for the conditional probability distributions of the states are obtained, based on which the optimal event-based state estimates can be further calculated, together with a closed-form expression of the average sensor-to-estimator communication rate. The effectiveness of the proposed results is illustrated by an application to a wireless automated machine health monitoring problem. Autors: Wentao Chen;Junzheng Wang;Dawei Shi;Ling Shi; Appeared in: IEEE Transactions on Automatic Control Publication date: Jul 2017, volume: 62, issue:7, pages: 3626 - 3633 Publisher: IEEE

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