Electrical and Electronics Engineering publications abstract of: 01-2018 sorted by title, page: 14

» PageSense: Toward Stylewise Contextual Advertising via Visual Analysis of Web Pages
Abstract:
The Internet has emerged as the most effective and a highly popular medium for advertising. Current contextual advertising platforms need publishers to manually change the original structure of their Web pages and predefine the position and style of embedded ads. Although publishers spend significant effort optimizing their Web page layout, a large number of Web pages contain noticeable blank regions. We present an innovative stylewise advertising platform for contextual advertising, called PageSense. The “style” of Web pages refers to the visual appearance of a Web page, such as color and layout. PageSense aims to associate style-consistent ads with Web pages. It provides two advertising options: 1) If publishers predefine ad positions within Web pages, PageSense will analyze the page style and select ads, which are consistent with the Web page layout, and 2) if publishers impose no constraints for ad placement, PageSense will automatically detect blank regions, select the most nonintrusive region for ad insertion, associate color-consistent ads with the Web pages, and deliver them to blank regions without breaking the original Web page style. Our experiments have verified the effectiveness of PageSense as a complement to existing contextual advertising.
Autors: Tao Mei;Lusong Li;Xinmei Tian;Dacheng Tao;Chong-Wah Ngo;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jan 2018, volume: 28, issue:1, pages: 254 - 266
Publisher: IEEE
 
» Parallel Balanced-Bit-Serial Design Technique for Ultra-Low-Voltage Circuits With Energy Saving and Area Efficiency Enhancement
Abstract:
Ultra-low-voltage (ULV) satisfies the energy-constraint on-die acceleration of parallel processing in battery-powered Internet-of-Things applications. However, ULV brings serious leakage energy, throughput reduction, and delay variation issues. Parallel bit-serialization remarkably reduces leakage energy and enhances area efficiency; however, extremely reduced critical path aggravates delay variation makes bit-serial operation not feasible to ULV design. In this paper, we propose a balanced-bit-serial adder (BBSA) as a basic unit of parallel-balanced-bit-serialization (PBBS) operation, which leverages timing borrowing to mitigate delay variation. In addition, we propose two latches to improve the effectiveness of timing borrowing and ease the area and power overhead of BBSA. The proposed BBSA is verified in TSMC 40-nm CMOS technology. Compared with the flip-flop-based bit-serial adder, energy consumption of BBSA is saved by 40% and area efficiency is improved by 15% as well. As a practical demonstration, we present a reconfigurable PBBS single instruction multiple data (SIMD) vector processing tile. The post-layout simulation shows that the proposed design has advantage of overall area efficiency and has significant energy saving as compared with the state-of-art ULV SIMD tile.
Autors: Bing-Chen Wu;I-Chyn Wey;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jan 2018, volume: 65, issue:1, pages: 141 - 153
Publisher: IEEE
 
» Parameter-Invariant Monitor Design for Cyber–Physical Systems
Abstract:
The tight interaction between information technology and the physical world inherent in cyber–physical systems (CPS) can challenge traditional approaches for monitoring safety and security. Data collected for robust CPS monitoring is often sparse and may lack rich training data describing critical events/attacks. Moreover, CPS often operate in diverse environments that can have significant inter/intra-system variability. Furthermore, CPS monitors that are not robust to data sparsity and inter/intra-system variability may result in inconsistent performance and may not be trusted for monitoring safety and security. Towards overcoming these challenges, this paper presents recent work on the design of parameter-invariant (PAIN) monitors for CPS. PAIN monitors are designed such that unknown events and system variability minimally affect the monitor performance. This work describes how PAIN designs can achieve a constant false alarm rate (CFAR) in the presence of data sparsity and intra/inter system variance in real-world CPS. To demonstrate the design of PAIN monitors for safety monitoring in CPS with different types of dynamics, we consider systems with networked dynamics, linear-time invariant dynamics, and hybrid dynamics that are discussed through case studies for building actuator fault detection, meal detection in type I diabetes, and detecting hypoxia caused by pulmonary shunts in infants. In all applications, the PAIN monitor is shown to have (significantly) less variance in monitoring performance and (often) outperforms other competing approaches in the literature. Finally, an initial application of PAIN monitoring for CPS security is presented along with challenges and research directions for future security monitoring deployments.
Autors: James Weimer;Radoslav Ivanov;Sanjian Chen;Alexander Roederer;Oleg Sokolsky;Insup Lee;
Appeared in: Proceedings of the IEEE
Publication date: Jan 2018, volume: 106, issue:1, pages: 71 - 92
Publisher: IEEE
 
» Parasitic Effect Analysis in Memristor-Array-Based Neuromorphic Systems
Abstract:
Neuromorphic systems using memristors as artificial synapses have attracted broad interest for energy-efficient computing applications. However, networks based on these purely passive devices can be affected by parasitic effects such as series resistance and sneak path problems. Here, we analyze the effects of parasitic factors on the performance of memristor-based neuromorphic systems. During vector-array multiplication, the line resistance can cause significant distortion of the output current and the activity of the corresponding neurons. An approach to compensate the line resistance effects based on an approximate model consisting of only few known parameters is proposed and shows excellent ability to capture the complex network behavior. During training and feature detection, the series resistance can cause significant degradation of the learned dictionary, with only a few dominant neurons being trained. Using a scaling factor based on the proposed simple model, these effects can be successfully mitigated, and the correct network operations can be restored. These results provide insight and practical measures on the parasitic effects for implementation of the neuromorphic system using memristor arrays.
Autors: YeonJoo Jeong;Mohammed A. Zidan;Wei D. Lu;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jan 2018, volume: 17, issue:1, pages: 184 - 193
Publisher: IEEE
 
» Parasitic Resistance-Based High Precision Capacitive MEMS Accelerometer Phase Shift and Its Usage for Temperature Compensation
Abstract:
A novel parasitic resistance-based high precision capacitive MEMS accelerometer temperature compensation method is proposed. The performance of MEMS accelerometer is severely affected by temperature drift. After a careful modeling analysis of the MEMS sensor, it is found that phase shift of the system is majorly affected by the parasitic resistor of the sensor cap. Thus, it can be used for sensor temperature compensation. Detailed analytic models and simulations are provided. Experimental results show that the bias stability is reduced from 0.26 to 0.18 mg after real-time temperature compensation. The temperature drift is reduced.
Autors: Yidong Liu;Tieying Ma;
Appeared in: IEEE Sensors Journal
Publication date: Jan 2018, volume: 18, issue:2, pages: 629 - 634
Publisher: IEEE
 
» Parcel-Based Active Learning for Large Extent Cultivated Area Mapping
Abstract:
This paper focuses on agricultural land cover mapping at a high-resolution scale and over large areas from an operational point of view and from a high-resolution monodate image. In this context, training data are assumed to be collected by successive journeys of field surveys and, thus, are very limited. Supervised learning techniques are generally used, assuming that the classes distribution is constant over the whole image. However, in practice, a data shift often occurs on large areas due to various acquisition conditions. To alleviate these issues, active learning (AL) techniques define an efficient training set by iteratively adapting it through adding the most informative unlabeled instances. They can improve the classification process efficiency while keeping a limited training dataset. The novelty in this paper is the application of AL techniques on multispectral images for agricultural land cover mapping, using field sampling instead of pixel sampling, which is rarely done in the literature. Besides, we proposed a parcel-based AL scheme that is suitable for an operational land cover mapping in cultivated areas since the parcel is an agricultural unit and field observations are processed at parcel scale. Random forests classifier was used. Results were processed on a 6 m multispectral Spot6 image over a 35 km Mediterranean cultivated area, in Lebna Catchment, north eastern Tunisia. The contribution of AL techniques was assessed with comparison to a random and stratified random strategies for sampling new instances. For iterative sample selection, two criteria are used and often coupled: uncertainty and diversity. For diversity metric, a new clustering-based metric was proposed based on a mean-shift clustering, which improved the classification accuracy. AL techniques showed to be efficient with complex data and fine land cover legend improving - andom-based selection up to 10%. Besides, the maximum of classification accuracy is reached using mean-shift breaking ties metric in just 5-day field survey, i.e., 30 days less compared to the random selection. Finally, results showed that the finer the definition of land cover classes, the more crucial is the choice of AL metrics.
Autors: Ines Ben Slimene Ben Amor;Nesrine Chehata;Jean-Stéphane Bailly;Imed Riadh Farah;Philippe Lagacherie;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Jan 2018, volume: 11, issue:1, pages: 79 - 88
Publisher: IEEE
 
» PARHELIA: Particle Filter-Based Heart Rate Estimation From Photoplethysmographic Signals During Physical Exercise
Abstract:
The photoplethysmographic (PPG) signal is an important source of information for estimating heart rate (HR). However, the PPG signal could be strongly contaminated by the motion artifact of the subjects, making HR estimation a particularly difficult problem. In this paper, we propose PARHELIA, a PARticle filter-based algorithm for HEart rate estimation using photopLethysmographIc signAls. The proposed method employs a particle filter, and utilizes the simultaneously recorded acceleration signals from a wrist-type sensor, to keep track of multiple HR candidates. This achieves quick recovery from incorrect HR estimations under the strong influence of the MA. Experimental results for a dataset of 12 subjects recorded during fast running showed that the average absolute estimation error was 1.17 beats per minute (BPM) whereas that of the best-known conventional method, JOSS, is 1.28 BPM. Furthermore, the estimation time of PARHELIA is 20 times shorter than JOSS.
Autors: Yuya Fujita;Masayuki Hiromoto;Takashi Sato;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jan 2018, volume: 65, issue:1, pages: 189 - 198
Publisher: IEEE
 
» Part I: On the Unification of Physics of Quasi-Saturation in LDMOS Devices
Abstract:
There have been a lot of ambiguities related to physics of quasi-saturation (QS) in laterally diffused MOS (LDMOS) devices in the published literature. For example, models that explain QS in input characteristics do not explain the same in output characteristics and vice versa. In addition to this, none of the earlier models explain early onset of QS at higher temperatures nor the models were validated using counter arguments. Attributed to this, a need for unified theory explaining physics of QS is justified in this paper. Furthermore, this paper for the first time, while addressing missing links between the observations reported in the past, develops a unified theory to explain physics of QS behavior. The theory presented here is independent of device architecture and covers all voltage-current–temperature trends. While considering velocity saturation and space charge modulation, we have discovered key role of high field mobility degradation of majority carriers and electric field screening, which is found to be the root cause of QS in LDMOS devices. The theory presented is further validated with numerous counter arguments. Finally, based on the new physical insight developed, we have proposed different approaches to mitigate QS effect. A detailed device design guideline to mitigate QS and its correlation with analog/RF performance, electo static discharge, hot-carrier reliability, self-heating, and safe operating area concern is presented in Part II of this paper.
Autors: B. Sampath Kumar;Mayank Shrivastava;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2018, volume: 65, issue:1, pages: 191 - 198
Publisher: IEEE
 
» Part II: RF, ESD, HCI, SOA, and Self Heating Concerns in LDMOS Devices Versus Quasi-Saturation
Abstract:
Various LDMOS device design parameters to mitigate quasi-saturation (QS) have been identified. Based on this, a set of independent and mixed device designs to mitigate QS, while maximizing the device performance, are presented. The impact of QS on the analog/RF/switching performance of these independent and mixed designs is investigated thoroughly, while analogizing performance with QS for the first time. Furthermore, hot carrier induced (HCI) degradation in various independent and mixed LDMOS designs is studied using spherical harmonic expansion of Boltzmann transport equation. In addition to this self-heating behavior, safe operating area (SOA) boundaries and electrostatic discharge (ESD) behavior of independent and mixed LDMOS designs with and without QS are studied. For the first time, HCI degradation, self-heating behavior, SOA boundary, and ESD failure in LDMOS devices are correlated with the extent of QS in LDMOS devices, based on which device design guidelines to tackle all performance versus reliability challenges are derived.
Autors: B. Sampath Kumar;Mayank Shrivastava;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2018, volume: 65, issue:1, pages: 199 - 206
Publisher: IEEE
 
» Partial-Discharge Measuring Produces Uncertain Results: Important Quality Assesment Updates for Stator Windings
Abstract:
The petrochemical industry considers the offline partial-discharge (PD) measurement an important quality assessment for new medium-voltage motor and generator stator windings. A recent edition of American Petroleum Institute (API) Standard 541 [1] requires an instrument to be compliant with International Electrotechnical Commission (IEC) Standard 60270 [3] for PD measurements on sacrificial stator coils and proposes 100 pC for guidance on acceptance criteria until more data becomes available. Given the industry's faith in PD as an acceptance test based on a representative sample, it warrants closer scrutiny. The characteristic PD distribution pattern produced by each test instrument provides information on the origin of the discharges and, therefore, can be used to determine what type of defect has produced them. This article shows how external factors such as instrument selection, testing environment, and time interval between tests can influence PD test results.
Autors: Saeed Ul Haq;Meredith K.W. Stranges;Barry Wood;
Appeared in: IEEE Industry Applications Magazine
Publication date: Jan 2018, volume: 24, issue:1, pages: 52 - 59
Publisher: IEEE
 
» PBTI in GaN-HEMTs With p-Type Gate: Role of the Aluminum Content on $Delta V_{mathrm {TH}}$ and Underlying Degradation Mechanisms
Abstract:
In this paper, we present an experimental analysis of the degradation induced by positive bias temperature instability stress in GaN-based power high electron mobility transistors with p-type gate, controlled by a Schottky metal/p-GaN junction. In particular, the role of the aluminum content (Al%) in the AlGaN barrier layer on the threshold voltage degradation is investigated by means of constant voltage stress measurements. This has been performed for different process conditions with varying Al content. Main results in this paper demonstrate that when a relatively large positive bias is applied on the gate, two competing trapping mechanisms take place in the AlGaN barrier layer or at the p-GaN/AlGaN interface causing instability. First, an aluminum independent hole trapping mechanism, caused by elastic tunneling from p-GaN valence band (2-D hole gas), leads to a relatively short-time and recoverable negative shift. In the second step, defect creation occurs. These additional defects are filled with electrons and cause a permanent or slowly recoverable positive degradation. The amount of defect creation was dependent on the Al% in the barrier.
Autors: Andrea Natale Tallarico;Steve Stoffels;Niels Posthuma;Paolo Magnone;Denis Marcon;Stefaan Decoutere;Enrico Sangiorgi;Claudio Fiegna;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2018, volume: 65, issue:1, pages: 38 - 44
Publisher: IEEE
 
» Pedestrian-Aware Engine Management Strategies for Plug-In Hybrid Electric Vehicles
Abstract:
Electric vehicles (EVs) and plug-in hybrid EVs (PHEVs) are increasingly being seen as a means of mitigating the pressing concerns of traffic-related pollution. While hybrid vehicles are usually designed with the objective of minimizing fuel consumption, in this paper we propose a engine management strategies that also consider environmental effects of the vehicles to pedestrians outside of the vehicles. Specifically, we present the optimisation-based engine energy management strategies for PHEVs that attempt to minimize the environmental impact of pedestrians along the route of the vehicle, while taking account of route-dependent uncertainties. We implement the proposed approach in a real PHEV and evaluate the performance in a hardware-in-the-loop platform. A variety of simulation results are given to illustrate the efficacy of our proposed approach.
Autors: Yingqi Gu;Mingming Liu;Joe Naoum-Sawaya;Emanuele Crisostomi;Giovanni Russo;Robert Shorten;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Jan 2018, volume: 19, issue:1, pages: 92 - 101
Publisher: IEEE
 
» Peer-Assisted Video Streaming With RTMFP Flash Player: A Measurement Study on PPTV
Abstract:
Real-time media flow protocol (RTMFP) is a protocol developed by Adobe for multimedia delivery under both client–server and peer-to-peer (P2P) paradigms. Currently, major Internet video service providers, such as PPTV and iQIYI, have already built their Web-based video streaming systems with RTMFP. In such a system, a user only needs to install a Flash Player plug-in on his Web browser, and can stream videos in a peer-assisted way. Despite its wide usage, RTMFP has received little attention from the measurement community. In this paper, we select PPTV as an example and study the RTMFP video streaming technology with a measurement approach. We reveal the architecture of PPTV’s RTMFP streaming system and show that, compared with proprietary P2P networks, the RTMFP network has a different content distribution policy, and exhibits different features on peers’ streaming behaviors, potential system bottleneck, and network dynamics. We also study RTMFP’s video transmission and find that the protocol’s selective retransmission scheme can effectively overcome packet losses and improve the video playback quality; however, the TCP-like congestion control mechanism of RTMFP does not lead to fairness between RTMFP and Transmission Control Protocol (TCP) traffics, due to the mismatch between the inherited pull-based video segment distribution model of the P2P streaming application and the protocol’s built-in congestion control mechanism. This paper provides insights into the RTMFP-based video streaming technology and is helpful for people to construct better peer-assisted video systems with RTMFP.
Autors: Shan Zou;Qiang Wang;Junqiang Ge;Ye Tian;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jan 2018, volume: 28, issue:1, pages: 158 - 170
Publisher: IEEE
 
» Performability Analysis of k-to-l-Out-of-n Computing Systems Using Binary Decision Diagrams
Abstract:
Modern computing systems typically utilize a large number of computing nodes to perform coordinated computations in parallel or simultaneously. They can exhibit multiple performance states or levels due to statuses or failures of their consistent nodes. Performability analysis is concerned with assessing the probability that the computing system performs at a particular performance level. In the context of performability analysis, these computing systems can be modeled using k-to-l-out-of-n structures. This paper proposes new analytical methods based on binary decision diagrams (BDD) for the performability analysis of large computing systems with unrepairable computing nodes. A new and efficient BDD algorithm that makes full uses of the special k -to-l-out-of-n structure is first proposed for systems with computing node having identical computing powers. New simplification rules are further proposed to generate compact and canonical BDD models for systems with heterogeneous computing nodes characterized by different computing powers. Ordering heuristic is also explored to further reduce the size of BDD models. Examples are provided to illustrate the proposed BDD-based performability analysis methodology as well as its efficiency in analyzing large-scale computing systems.
Autors: Yuchang Mo;Liudong Xing;Joanne Bechta Dugan;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Jan 2018, volume: 15, issue:1, pages: 126 - 137
Publisher: IEEE
 
» Performability Modeling for RAID Storage Systems by Markov Regenerative Process
Abstract:
This paper presents a performability model for RAID storage systems using Markov regenerative process to compare different RAID architectures. While homogeneous Markov models are extensively used for reliability analysis of RAID storage systems, the memory-less property of the sojourn time assumed in such models is not satisfied in reality, especially in disk rebuild process whose progress is not interrupted even at an event of another disk failure. In this paper, we use Markov regenerative process which allows us to model the generally distributed rebuild times providing a needed extension of the traditional Markov models. The Markov regenerative process is then used to assess the performability of the storage system by assigning reward rates to each state based on the real storage benchmark results. Our numerical study characterizes the performability advantage of RAID6 architecture over RAID10 architecture in terms of sequential read access. Our findings include that the effect of exponential assumption for the rebuild times has practically negligible effect when we focus on data availability. However, the effect this approximation on performability prediction may not be negligible especially when the performance level drastically changes in degraded states. Our MRGP model provides more accurate prediction of performability in such cases.
Autors: Fumio Machida;Ruofan Xia;Kishor S. Trivedi;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Jan 2018, volume: 15, issue:1, pages: 138 - 150
Publisher: IEEE
 
» Performance Analysis for the ${N}$ -Continuous Precoded SM-OFDM System
Abstract:
Combined with N-continuous (NC) precoding, the spatial modulation (SM) orthogonal frequency division multiplexing (OFDM) system offers considerable sidelobe suppression for the downlink transmission, at the cost of additional interference to the transmit signal. Therefore, this paper focuses on investigating the impact of the NC precoder on the bit error rate (BER) performance of the SM-OFDM system. The BER performance is analyzed over the frequency-selective Rayleigh fading channel under two distinct scenarios, i.e., perfect channel estimation and interference suppression based minimum mean square error (MMSE) channel estimation. First, we propose an approximate system model for the NC precoded SM-OFDM system along with an analysis on the introduced interference, and then derive the average BER performance of the system with perfect channel estimation. Based on the above proposed approximate system model, we further analyze the interference based upon MMSE channel estimation, and investigate the characteristics of channel estimation errors. Furthermore, we derive the average BER performance of the NC precoded SM-OFDM system with imperfect channel estimation. The numerical results show that the analytical BER closely matches its simulated counterpart under different system configurations, and demonstrate that the proposed approximate system model is in good agreement with the precise one.
Autors: Yue Xiao;Feng Yu;Xia Lei;Dongxiao He;Ping Yang;Wei Xiang;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2018, volume: 67, issue:1, pages: 483 - 493
Publisher: IEEE
 
» Performance Analysis of Multiuser Massive MIMO With Spatially Correlated Channels Using Low-Precision ADC
Abstract:
In this letter, we analyze the uplink performance of a multiuser massive MIMO system with spatially correlated channels using low-precision analog-to-digital convertors (ADCs) at the base station. A tight closed-form approximated sum rate for receivers with imperfect channel state information is derived. We further investigate the impact of the spatial correlation on the rate loss caused by low-precision ADC and find that this rate loss is currently overestimated for massive MIMO under spatially correlated channels. This observation promotes the use of low-precision ADC in practical massive MIMO with inherent spatial correlation.
Autors: Peihao Dong;Hua Zhang;Wei Xu;Geoffrey Ye Li;Xiaohu You;
Appeared in: IEEE Communications Letters
Publication date: Jan 2018, volume: 22, issue:1, pages: 205 - 208
Publisher: IEEE
 
» Performance Analysis of NOMA in Training-Based Multiuser MIMO Systems
Abstract:
This paper considers the use of non-orthogonal-multiple-access (NOMA) in multiuser MIMO systems in practical scenarios where channel state information (CSI) is acquired through pilot signaling. A new NOMA scheme that uses shared pilots is proposed. Achievable rate analysis is carried out for different pilot signaling schemes, including both uplink and downlink pilots. The achievable rate performance of the proposed NOMA scheme with shared pilot within each group is compared with the traditional orthogonal access scheme with orthogonal pilots. Our proposed scheme is a generalization of the orthogonal scheme, and can be reduced to the orthogonal scheme when appropriate power allocation parameters are chosen. Numerical results show that when downlink CSI is available at the users, our proposed NOMA scheme outperforms orthogonal schemes. However with more groups of users present in the cell, it is preferable to use multi-user beamforming instead of NOMA.
Autors: Hei Victor Cheng;Emil Björnson;Erik G. Larsson;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2018, volume: 17, issue:1, pages: 372 - 385
Publisher: IEEE
 
» Performance Enhancement of a Dielectric Barrier Discharge Vacuum-Ultraviolet Photon Source Using Short-Pulsed Electrical Excitation
Abstract:
We have studied the electrical and optical characteristics of an air-cooled argon excimer vacuum-ultraviolet lamp ( nm) excited by a dielectric barrier discharge powered by: 1) pulsed or 2) sinusoidal high-voltage drivers from 32 to 100 kHz. Compared to sinusoidal excitation, pulsed excitation gives nearly higher vacuum-ultraviolet (VUV) output and electrical-to-VUV conversion efficiency at high pressure (800–900 mbar). Visually, the pulse-driven plasma is spatially homogeneous, whereas for sinusoidal excitation the plasma becomes filamentary at higher pressure and/or frequency. Spectral emission is highly monochromatic with most of the output in the desired VUV band (–140 nm). With the lamp running at pressure >700 mbar and power loadings >1.6 W/cm3, a sharp spike in VUV output was consistently seen at turn-on. We believe that transient phenomena or favorable initial conditions may be partly responsible for this VUV spike, although the equilibrium VUV output appears to be limited due to thermal dissipation, gas heating, and associated loss of gas from the active region. We propose that we may be observing the same intrinsic VUV spiking phenomena as reported in liquid nitrogen-cooled Xe, Kr, and Ar excimer lamps by Gerasimov et al. More importantly, we believe ours is the first such observation reported for an excimer VUV lamp operating near room temperature. This VUV spiking behavior raises the prospect that designs with improved thermal management may achieve even higher VUV power and efficiency.
Autors: Robert J. Carman;Noah T. Goldberg;Stuart C. Hansen;Nigel Gore;Deborah M. Kane;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jan 2018, volume: 46, issue:1, pages: 90 - 102
Publisher: IEEE
 
» Performance Evaluation of a Multi-radio, Multi-hop Ad-hoc Radio Communication Network for Communications-Based Train Control (CBTC)
Abstract:
Communications-based train control (CBTC) is a modern signaling system that uses radio communication to transfer train control information between the train and the wayside. A vast majority of CBTC systems worldwide use IEEE 802.11 Wi-Fi as the radio technology mostly due to its cost effectiveness. The trackside networks in these systems are mostly based on the conventional infrastructure Wi-Fi. It means a train has to continuously associate (i.e., perform handshake) with the trackside Wi-Fi access points (AP) as it moves. This is a time-consuming process associated with a certain delay. Additionally, these APs are connected to the wayside infrastructure via optical fiber cables that incurs huge costs. This paper presents a novel design in which trackside nodes function in ad-hoc Wi-Fi mode, which means no association has to be performed with them prior to transmitting. A train simply broadcasts packets to any nodes in its range. A node upon receiving these packets forwards them to the next node and so on, forming a chain of nodes. Following this chain, packets arrive at the destination. To make the design resilient against interference, transmissions are separated on multiple frequencies. Furthermore, redundancy is introduced in the design as a node forwards packets to not only one but two of its neighbors. This paper investigates the performance of the new design from the perspective of resiliency, redundancy, and scalability, and presents the results both from a field experiment carried out using prototype hardware and an extensive simulations study.
Autors: Jahanzeb Farooq;Lars Bro;Rasmus Thystrup Karstensen;José Soler;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2018, volume: 67, issue:1, pages: 56 - 71
Publisher: IEEE
 
» Performance Evaluation of Passivated Silicon Carrier-Selective Contact Solar Cell
Abstract:
In this paper, a solar cell with amorphous silicon (a-Si) passivation that uses transition metal oxides (TMOs) for charge carrier collection has been modeled and analyzed for its performance. Charge carrier selection has been incorporated through selective band alignment provided by NiO and TiO2 TMOs for electrons and holes, respectively. The presence of a-Si interfacial layers for defect passivation prevents carrier loss due to high interface state densities at the Si/TMO interfaces. This structure is a potential candidate for high-efficiency solar cells (>25%) with a realistic approach towards the solution of high defect density. Optical analysis of the proposed structure has been done to analyze the amount of light entering the silicon and capable of generating electron–hole pairs. The amount of light lost has also been quantified into reflection loss, parasitic absorption, and back metal absorption. Impact of surface passivation quality and doping of NiO and TiO2 on its performance has been analyzed through the detailed device simulations. This provides a realistic pathway for engineering of passivation quality and doping of metal oxides for improved performance.
Autors: Astha Tyagi;Kunal Ghosh;Anil Kottantharayil;Saurabh Lodha;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2018, volume: 65, issue:1, pages: 176 - 183
Publisher: IEEE
 
» Performance of Brain–Computer Interfacing Based on Tactile Selective Sensation and Motor Imagery
Abstract:
A large proportion of users do not achieve adequate control using current non-invasive brain–computer interfaces (BCIs). This issue has being coined “BCI-Illiteracy” and is observed among different BCI modalities. Here, we compare the performance and the BCI-illiteracy rate of a tactile selective sensation (SS) and motor imagery (MI) BCI, for a large subject samples. We analyzed 80 experimental sessions from 57 subjects with two-class SS protocols. For SS, the group average performance was 79.8 ± 10.6%, with 43 out of the 57 subjects (75.4%) exceeding the 70% BCI-illiteracy threshold for left- and right-hand SS discrimination. When compared with previous results, this tactile BCI outperformed all other tactile BCIs currently available. We also analyzed 63 experimental sessions from 43 subjects with two-class MI BCI protocols, where the group average performance was 77.2 ± 13.3%, with 69.7% of the subjects exceeding the 70% performance threshold for left- and right-hand MI. For within-subject comparison, the 24 subjects who participated to both the SS and MI experiments, the BCI performance was superior with SS than MI especially in beta frequency band (p < 0.05), with enhanced R2 discriminative information in the somatosensory cortex for the SS modality. Both SS and MI showed a functional dissociation between lower alpha ([8 10] Hz) and upper alpha ([10 13] Hz) bands, with BCI performance significantly better in the upper alpha than the lower alpha (p < 0.05) band. In summary, we demonstrated that SS is a promising BCI modality with low BCI illiteracy issue and has great potential in practical applications reaching large population.
Autors: Lin Yao;Xinjun Sheng;Natalie Mrachacz-Kersting;Xiangyang Zhu;Dario Farina;Ning Jiang;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Jan 2018, volume: 26, issue:1, pages: 60 - 68
Publisher: IEEE
 
» Performance of Generalized Spatial Modulation MIMO Over Measured 60GHz Indoor Channels
Abstract:
In this paper, we study the capacity and symbol error probability (SEP) of generalized spatial modulation (GSM) multiple-input multiple-output (MIMO) using measured channels that are obtained by channel sounding in an indoor office environment at 60GHz. Spatial modulation (SM) and GSM are emerging low-complexity MIMO schemes that have been extensively researched for low-GHz (below 6GHz) communications. Recently, they have been considered and shown to be promising also for (mmWave) communications. In the simplest possible case, they require only one RF chain both at the transmitter (TX) and receiver (RX), and thus, are especially attractive for mmWave communications, in which the number of RF chains needs to be as low as possible. Despite of some early works on the theoretical analysis of SM/GSM for mmWave communications, there have been no investigations using real-world channel data. We focus on the office line-of-sight (LOS) scenario and investigate three problems: 1) the performance of GSM using the extracted LOS component of measured channels; 2) the impact of non-LOS NLOS components on the performance of GSM; and 3) possible simple modulation and reception algorithms for GSM that rely only on the LOS component of the channel. The results being reported in this paper not only validate the main claims of previous studies based on ideal pure LOS channels, but also lead to novel findings. One major conclusion is that NLOS components are harmful to the SEP of GSM and should be avoided. As another important outcome, our results strongly motivate the use of precoding in GSM systems to simultaneously improve the channel capacity and reduce the physical size of MIMO arrays (thus eliminating one major issue of LOS GSM).
Autors: Peng Liu;Jiri Blumenstein;Nemanja Stefan Perović;Marco Di Renzo;Andreas Springer;
Appeared in: IEEE Transactions on Communications
Publication date: Jan 2018, volume: 66, issue:1, pages: 133 - 148
Publisher: IEEE
 
» Performance of Mode Space Detector in Uncertain Shallow Water and Its Robust Realization
Abstract:
The statistics of the mode space detector (MSD) whose modes are characterized by some degree of mismatch to truth [that is, the mismatched mode space detector (MMSD)] are derived. As a measure of the “containing relation” between the mode spaces derived from different environmental realizations we propose the relative projection error metric, through which the performance of the MMSD can be further investigated and compared to the MSD using accurate environmental knowledge. From this performance analysis, we suggest that by simply using the greatest dimensional physically supported mode space, we can obtain a robust MSD. It can achieve the same performance robustness as the energy detector—the performance is only determined by the array signal energy and is insensitive to the specific source position and environmental conditions. It can also avoid the potentially-significant performance degradation of the Bayesian detector when applied to certain deterministic scenarios at a cost of small average performance degradation. Numerical simulations in a typical uncertain shallow-water environment support our assertions.
Autors: Mingyang Li;Chao Sun;Peter Willett;
Appeared in: IEEE Journal of Oceanic Engineering
Publication date: Jan 2018, volume: 43, issue:1, pages: 131 - 144
Publisher: IEEE
 
» Performance of Pad Front-End Board for Small-Strip Thin Gap Chamber With Cosmic Ray Muons
Abstract:
We report on the characterization of pad front-end board (pFEB) for small-strip thin gap chamber (sTGC) prototype. The pFEB is based on field programmable gate array (FPGA) and application-specific integrated circuit. It has been built to verify the capabilities of the sTGC detector for the ATLAS Phase-I new small wheel upgrade. The pFEB consists of three VMM2 front-end chips, two Kintex-7 FPGAs used to buffer the VMM2 data, a gigabit ethernet transceiver (GET), and all the required connectors. The VMM2, designed at Brookhaven National Laboratory, is composed of 64 linear front-end channels. Each channel integrates a charge sensitive amplifier, a shaper, a stable band-gap referenced baseline, several analog-to-digital converters, and other functions. The GET works at physical layer of the network. The mini-serial attached SCSI connector accepts three external signals (40-MHz clock, reset, and trigger), which are used for synchronization of several pFEBs. In addition, the pFEB can work in the case of self-trigger mode and external trigger mode. The specific characteristics and implementations are described in detail. Also, the performance of this new type of sTGC detector has been studied with cosmic ray muons.
Autors: Feng Li;Shengquan Liu;Kun Hu;Xu Wang;Houbing Lu;Xinxin Wang;Hang Yang;Tianru Geng;Peng Miao;Ge Jin;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: Jan 2018, volume: 65, issue:1, pages: 597 - 603
Publisher: IEEE
 
» Persistent Scatter Identification and Look-Angle Error Estimation Using Similar Time-Series Interferometric Pixels
Abstract:
Persistent scatterer (PS) pixels contain highly coherent information, which is used in the estimation of geophysical parameters of interest. Conventionally, PS pixels are selected on the basis of the estimated noise present in the spatially uncorrelated phase component along with look-angle error. The phase history of selected PS pixels is corrected for the look-angle error followed by phase unwrapping and extraction of spatially correlated nuisance phase component leading to displacement estimation. In this letter, a novel PS selection method, which is based on a new index called the similar time-series interferometric pixels (STIPs) representing the number of neighborhood pixels with similar phase history, is proposed. In this approach, apart from PS selection, corresponding set of STIP is also used in refining look-angle error estimation. The efficiency of the proposed InSAR processing chain is demonstrated for the Sentinel-1A single look complex images of Rajmahal, Jharkhand, India, predominantly a coal mines area. Results, when compared with the conventional PS processing technique, reveal substantial improvement in terms of extracting more number of reliable PS with enhanced density.
Autors: Avadh Bihari Narayan;Ashutosh Tiwari;Ramji Dwivedi;Onkar Dikshit;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jan 2018, volume: 15, issue:1, pages: 147 - 150
Publisher: IEEE
 
» Personalized and Diverse Task Composition in Crowdsourcing
Abstract:
We study task composition in crowdsourcing and the effect of personalization and diversity on performance. A central process in crowdsourcing is task assignment, the mechanism through which workers find tasks. On popular platforms such as Amazon Mechanical Turk, task assignment is facilitated by the ability to sort tasks by dimensions such as creation date or reward amount. Task composition improves task assignment by producing for each worker, a personalized summary of tasks, referred to as a Composite Task (CT). We propose different ways of producing CTs and formulate an optimization problem that finds for a worker, the most relevant and diverse CTs. We show empirically that workers’ experience is greatly improved due to personalization that enforces an adequation of CTs with workers’ skills and preferences. We also study and formalize various ways of diversifying tasks in each CT. Task diversity is grounded in organization studies that have shown its impact on worker motivation  [33] . Our experiments show that diverse CTs contribute to improving outcome quality. More specifically, we show that while task throughput and worker retention are best with ranked lists, crowdwork quality reaches its best with CTs diversified by requesters, thereby confirming that workers look to expose their “good” work to many requesters.
Autors: Maha Alsayasneh;Sihem Amer-Yahia;Eric Gaussier;Vincent Leroy;Julien Pilourdault;Ria Mae Borromeo;Motomichi Toyama;Jean-Michel Renders;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jan 2018, volume: 30, issue:1, pages: 128 - 141
Publisher: IEEE
 
» Personalized Risk Scoring for Critical Care Prognosis Using Mixtures of Gaussian Processes
Abstract:
Objective: In this paper, we develop a personalized real-time risk scoring algorithm that provides timely and granular assessments for the clinical acuity of ward patients based on their (temporal) lab tests and vital signs; the proposed risk scoring system ensures timely intensive care unit admissions for clinically deteriorating patients. Methods: The risk scoring system is based on the idea of sequential hypothesis testing under an uncertain time horizon. The system learns a set of latent patient subtypes from the offline electronic health record data, and trains a mixture of Gaussian Process experts, where each expert models the physiological data streams associated with a specific patient subtype. Transfer learning techniques are used to learn the relationship between a patient's latent subtype and her static admission information (e.g., age, gender, transfer status, ICD-9 codes, etc). Results: Experiments conducted on data from a heterogeneous cohort of 6321 patients admitted to Ronald Reagan UCLA medical center show that our score significantly outperforms the currently deployed risk scores, such as the Rothman index, MEWS, APACHE, and SOFA scores, in terms of timeliness, true positive rate, and positive predictive value. Conclusion: Our results reflect the importance of adopting the concepts of personalized medicine in critical care settings; significant accuracy and timeliness gains can be achieved by accounting for the patients’ heterogeneity. Significance: The proposed risk scoring methodology can confer huge clinical and social benefits on a massive number of critically ill inpatients who exhibit adverse outcomes including, but not limited to, cardiac arrests, respiratory arrests, and septic shocks.
Autors: Ahmed M. Alaa;Jinsung Yoon;Scott Hu;Mihaela van der Schaar;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jan 2018, volume: 65, issue:1, pages: 207 - 218
Publisher: IEEE
 
» PES Connections: Being Relevant to the Global Working Professional [Leader's Corner]
Abstract:
Autors: Saifur Rahman;
Appeared in: IEEE Power and Energy Magazine
Publication date: Jan 2018, volume: 16, issue:1, pages: 10 - 12
Publisher: IEEE
 
» Phantomless Auto-Calibration and Online Calibration Assessment for a Tracked Freehand 2-D Ultrasound Probe
Abstract:
This paper presents a method for automatically calibrating and assessing the calibration quality of an externally tracked 2-D ultrasound (US) probe by scanning arbitrary, natural tissues, as opposed a specialized calibration phantom as is the typical practice. A generative topic model quantifies the posterior probability of calibration parameters conditioned on local 2-D image features arising from a generic underlying substrate. Auto-calibration is achieved by identifying the maximum a-posteriori image-to-probe transform, and calibration quality is assessed online in terms of the posterior probability of the current image-to-probe transform. Both are closely linked to the 3-D point reconstruction error (PRE) in aligning feature observations arising from the same underlying physical structure in different US images. The method is of practical importance in that it operates simply by scanning arbitrary textured echogenic structures, e.g., in-vivo tissues in the context of the US-guided procedures, without requiring specialized calibration procedures or equipment. Observed data take the form of local scale-invariant features that can be extracted and fit to the model in near real-time. Experiments demonstrate the method on a public data set of in vivo human brain scans of 14 unique subjects acquired in the context of neurosurgery. Online calibration assessment can be performed at approximately 3 Hz for the US images of pixels. Auto-calibration achieves an internal mean PRE of 1.2 mm and a discrepancy of [2 mm, 6 mm] in comparison to the calibration via a standard phantom-based method.
Autors: Matthew Toews;William M. Wells;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jan 2018, volume: 37, issue:1, pages: 262 - 272
Publisher: IEEE
 
» Phase Retrieval Without Small-Ball Probability Assumptions
Abstract:
In the context of the phase retrieval problem, it is known that certain natural classes of measurements, such as Fourier measurements and random Bernoulli measurements, do not lead to the unique reconstruction of all possible signals, even in combination with certain practically feasible random masks. To avoid this difficulty, the analysis is often restricted to measurement ensembles (or masks) that satisfy a small-ball probability condition, in order to ensure that the reconstruction is unique. This paper shows a complementary result: for random Bernoulli measurements, there is still a large class of signals that can be reconstructed uniquely, namely, those signals that are non-peaky. In fact, this result is much more general: it holds for random measurements sampled from any subgaussian distribution , without any small-ball conditions. This is demonstrated in two ways: 1) a proof of stability and uniqueness and 2) a uniform recovery guarantee for the PhaseLift algorithm. In all of these cases, the number of measurements approaches the information-theoretic lower bound. Finally, for random Bernoulli measurements with erasures, it is shown that PhaseLift achieves uniform recovery of all signals (including peaky ones).
Autors: Felix Krahmer;Yi-Kai Liu;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jan 2018, volume: 64, issue:1, pages: 485 - 500
Publisher: IEEE
 
» Phase Transformation of Micrometer-Sized Mn–Al–C
Abstract:
Mn54Al46C2.44 alloy as new permanent magnetic materials was produced by induction melting, and its powders were produced by low energy ball milling. The milled powders were annealed to study the effect on their phase transformation and magnetic properties. The powder undergoes massive phase transformation at an annealing temperature of 450 °C, and reaches the maximum saturation magnetization ( when annealed at 480 °C for 5 min, while its intrinsic coercivity ( continually increases with the temperature. The initial increment of the is due to the phase transformation from paramagnetic -phase to ferromagnetic -phase and remaining -phase and formation of secondary phases, such as nonmagnetic - and -phases, that acts as pinning points for the domain walls. The next one is caused by the increasing percentage of the secondary phases that decreases . Based on the delta analysis, it can be verified that the increased with increasing secondary phases when annealed at temperat- res above 480 °C is due to the decreasing magnetization.
Autors: Jihoon Park;Hui-Dong Qian;Ping-Zhan Si;Chul-Jin Choi;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jan 2018, volume: 54, issue:1, pages: 1 - 3
Publisher: IEEE
 
» Phased Array Focusing for Acoustic Wireless Power Transfer
Abstract:
Wireless power transfer (WPT) through acoustic waves can achieve higher efficiencies than inductive coupling when the distance is above several times the transducer size. This paper demonstrates the use of ultrasonic phased arrays to focus power to receivers at arbitrary locations to increase the power transfer efficiency. Using a phased array consisting of 37 elements at a distance nearly 5 times the receiver transducer diameter, a factor of 2.6 increase in efficiency was achieved when compared to a case equivalent to a single large transducer with the same peak efficiency distance. The array has a total diameter of 7 cm, and transmits through air at 40 kHz to a 1.1-cm diameter receiver, achieving a peak overall efficiency of 4% at a distance of 5 cm. By adjusting the focal distance, the efficiency can also be maintained relatively constant at distances up to 9 cm. Numerical models were developed and shown to closely match the experimental energy transfer behavior; modeling results indicate that the efficiency can be further doubled by increasing the number of elements. For comparison, an inductive WPT system was also built with the diameters of the transmitting and receiving coils equivalent to the dimensions of the transmitting ultrasonic phased array and receiver transducer, and the acoustic WPT system achieved higher efficiencies than the inductive WPT system when the transmit-to-receive distance is above 5 cm. In addition, beam angle steering was demonstrated by using a simplified seven-element 1-D array, achieving power transfer less dependent on receiver placement.
Autors: Victor Farm-Guoo Tseng;Sarah S. Bedair;Nathan Lazarus;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Jan 2018, volume: 65, issue:1, pages: 39 - 49
Publisher: IEEE
 
» Phasor Alternatives to Friis’ Transmission Equation
Abstract:
Two alternatives to Friis’ transmission equation in terms of phasor voltage waves are presented. In one formulation, antennas are characterized by the complex effective length vectors. An additional form introducing field gain, which serves effectively as a phasor counterpart to the power gain, is proposed. Both forms show the same degree of symmetry and modularity as the original Friis’ equation, but thanks to using phasors instead of power quantities, they allow for superposition of fields or voltages. Although the new transmission equations are formulated in a frequency domain, they also constitute a simple and intuitive way to calculate time-domain responses of antennas, such as in ultrawideband systems. Application of the equations is demonstrated on a simple example of coupling between two nonaligned dipoles in the vicinity of a conductive reflector.
Autors: Ondřej Franek;
Appeared in: IEEE Antennas and Wireless Propagation Letters
Publication date: Jan 2018, volume: 17, issue:1, pages: 90 - 93
Publisher: IEEE
 
» Phasor Measurement Sensor-Based Angular Stability Retention System for Smart Power Grids With High Penetration of Microgrids
Abstract:
Emerging phasor measurement sensor (PMS) technology is revolutionizing conventional power grids to smart power grids (SPGs). This also paves the way for deregulations in energy market and wide area infusion of distributed energy-based systems like microgrids (MGs). Advanced energy management of MGs for better consumer gratification may pose severe threat to angular stability of SPGs. This paper outlines the angular stability issues that may emerge in SPGs due to high penetration of MGs. PMS-powered stability monitoring and MG operational-based stability retention technique are proposed for retaining the angular stability. Real-time frequency domain analysis of phase angle oscillations measured from PMS across the grid is the backbone of the proposed stability monitoring technique. Wide area optimized control of MGs with the aid of topological genetic algorithm is proposed for restraining the stability. Case studies conducted on standard bus systems portray the impact of high penetration of MGs on angular stability and the effectiveness of proposed techniques in monitoring and retaining the stability.
Autors: Pathirikkat Gopakumar;Maddikara Jaya Bharata Reddy;Dusmanta Kumar Mohanta;
Appeared in: IEEE Sensors Journal
Publication date: Jan 2018, volume: 18, issue:2, pages: 764 - 772
Publisher: IEEE
 
» PhenoLines: Phenotype Comparison Visualizations for Disease Subtyping via Topic Models
Abstract:
PhenoLines is a visual analysis tool for the interpretation of disease subtypes, derived from the application of topic models to clinical data. Topic models enable one to mine cross-sectional patient comorbidity data (e.g., electronic health records) and construct disease subtypes—each with its own temporally evolving prevalence and co-occurrence of phenotypes—without requiring aligned longitudinal phenotype data for all patients. However, the dimensionality of topic models makes interpretation challenging, and de facto analyses provide little intuition regarding phenotype relevance or phenotype interrelationships. PhenoLines enables one to compare phenotype prevalence within and across disease subtype topics, thus supporting subtype characterization, a task that involves identifying a proposed subtype's dominant phenotypes, ages of effect, and clinical validity. We contribute a data transformation workflow that employs the Human Phenotype Ontology to hierarchically organize phenotypes and aggregate the evolving probabilities produced by topic models. We introduce a novel measure of phenotype relevance that can be used to simplify the resulting topology. The design of PhenoLines was motivated by formative interviews with machine learning and clinical experts. We describe the collaborative design process, distill high-level tasks, and report on initial evaluations with machine learning experts and a medical domain expert. These results suggest that PhenoLines demonstrates promising approaches to support the characterization and optimization of topic models.
Autors: Michael Glueck;Mahdi Pakdaman Naeini;Finale Doshi-Velez;Fanny Chevalier;Azam Khan;Daniel Wigdor;Michael Brudno;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Publication date: Jan 2018, volume: 24, issue:1, pages: 371 - 381
Publisher: IEEE
 
» Photo-Electrical Properties of MgZnO Thin-Film Transistors With High- ${k}$ Dielectrics
Abstract:
In this letter, magnesium zinc oxide (MgZnO) was deposited to fabricate a thin-film transistor (TFT) by radio-frequency magnetron sputtering. We used alumina as MgZnO TFT gate insulator layer via an atomic layer deposition method. The MgZnO TFT with Al2O3 insulator could exhibit a mobility of 7.73 cm2/Vs, threshold voltage of 4.2 V, and subthreshold swing of 0.29 V/decade. Compared with our previous published study, the current switching ratio was improved by nearly two orders of magnitude. Furthermore, the hysteresis phenomenon had been investigated and the results showed that the high- gate insulator could improve the interface state caused by the traps.
Autors: Jyun-Yi Li;Sheng-Po Chang;Ming-Hung Hsu;Shoou-Jinn Chang;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2018, volume: 30, issue:1, pages: 59 - 62
Publisher: IEEE
 
» Photodarkening-Free Yb-Doped Saddle-Shaped Fiber for High Power Single-Mode 976-nm Laser
Abstract:
We propose a novel saddle-shaped Yb-doped fiber design for high power generation in the spectral range near 0.976 . The fiber has a central single-mode part with a core diameter of approximately and an ultra-thin silica clad of approximately . At both ends of the fiber, the core/clad diameters were adiabatically increased up to 20/80 to be compatible with ordinary passive fibers. A monolithic 976-nm single-mode continuous wave laser based on the proposed fiber was created. The laser’s power was a record high compared with all-fiber laser schemes, with an output power of 10.6 W. Utilization of a photodarkening-free core glass matrix has allowed us to demonstrate perfect long-term stability (without any power degradation) of the developed laser over 45 h.
Autors: Svetlana S. Aleshkina;Andrei E. Levchenko;Oleg I. Medvedkov;Konstantin K. Bobkov;Mikhail M. Bubnov;Denis S. Lipatov;Alexei N. Guryanov;Mikhail E. Likhachev;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2018, volume: 30, issue:1, pages: 127 - 130
Publisher: IEEE
 
» Photonic Crystal-Based High-Power Backward Wave Oscillator
Abstract:
An electron beam traversing a slow wave structure can be used to either generate or amplify electromagnetic radiation through the interaction of the slow space charge wave on the beam with the slow wave structure modes. Here, a cylindrical waveguide with a periodic array of conducting loops is used for the slow wave structure. This paper considers operation as a backward wave oscillator. The dispersion properties of the structure are determined using a frequency-domain eigenmode solver. The interaction of the electron beam with the structure modes is investigated using a 2-D particle-in-cell (PIC) code. The operating frequency and growth rate dependence on beam energy and beam current are investigated using the PIC code and compared with analytic and scaling estimates where possible.
Autors: Brian R. Poole;John R. Harris;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jan 2018, volume: 46, issue:1, pages: 25 - 32
Publisher: IEEE
 
» Physical-Layer Security in Multiuser Visible Light Communication Networks
Abstract:
In this paper, we study the physical-layer security in a 3-D multiuser visible light communication (VLC) network. The locations of access points (APs) and mobile users are modeled as two 2-D, independent and homogeneous Poisson point processes at distinct heights. Using mathematical tools from stochastic geometry, we provide a new analytical framework to characterize the secrecy performance in multiuser VLC networks. Closed-form results for the outage probability and the ergodic secrecy rate are derived for networks without AP cooperation. Considering the cooperation among APs, we give tight lower and upper bounds on the secrecy outage probability and the ergodic secrecy rate. To further enhance the secrecy performance at the legitimate user, a disk-shaped secrecy protected zone is implemented in the vicinity of the transmit AP. Based on the obtained results, it is shown that cooperating neighboring APs in a multiuser VLC network can bring performance gains on the secrecy rate, but only to a limited extent. We also show that building an eavesdropper-free protected zone around the AP significantly improves the secrecy performance of legitimate users, which appears to be a promising solution for the design of multiuser VLC networks with high security requirements.
Autors: Liang Yin;Harald Haas;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: Jan 2018, volume: 36, issue:1, pages: 162 - 174
Publisher: IEEE
 
» Physics-Based Co-Simulation Platform With Analytical and Experimental Verification for Bidirectional IPT System in EV Applications
Abstract:
Inductive power transfer (IPT) technology has been approved to be convenient and reliable interface for charging and discharging the electric vehicles (EVs). Precise model for such system can help designers and researchers to anticipate, optimize, and evaluate its behavior amid the development. Thus, this paper presents a physics-based co-simulation platform for the bidirectional IPT system (BIPTS) in EVs’ applications. The platform is established through the coupling between finite element and circuit analysis. The power electronic converters and controllers are developed in Simulink; and the power pads are modeled in Magnet environment. The two parts are lined together through the compatible Simulink plug-in tool. In addition, a state-space dynamic mathematical model for the same BIPTS is derived and implemented in MATLAB environment. A 1.2 kW BIPTS is analyzed under different dynamics by both models and the results are compared. The effect of the nonlinearities and the magnetic material characteristics on the BIPTS's performance is assessed, in terms of errors and harmonics analysis. The analysis considered both the full and light loading operating conditions in the system. Finally, a small-scale prototype for a BIPTS is built, tested, and compared with the co-simulation results for verification purposes. The proposed co-simulation could provide accurate prediction for the system's dynamics, during both charging and discharging operation. The scheme is generic and can be easily expanded to different pad structures, compensation networks, and converter topologies.
Autors: Ahmed A. S. Mohamed;Osama Mohammed;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2018, volume: 67, issue:1, pages: 275 - 284
Publisher: IEEE
 
» Piecewise Variable Parameter Loss Model of Laminated Steel and Its Application in Fine Analysis of Iron Loss of Inverter-Fed Induction Motors
Abstract:
Due to the coaction of supply harmonics and the harmonics resulting from the motor structures, the mechanism and distribution characteristics of iron losses become more complicated in inverter-fed induction motors. Therefore, accurate prediction and fine analysis of iron loss are very important at the design stage of high-efficiency inverter-fed induction motors. In order to predict the iron losses accurately, this paper proposes a piecewise iron loss model whose parameters vary with the magnitude and frequency of flux density, and two additional flux density terms are introduced to the classical iron loss model considering the nonlinearity of magnetic material and harmonic fields. With this model, the iron losses are calculated for an inverter-fed 5.5 kW induction motor. The results reveal the distribution characteristics of hysteresis and eddy current losses in stator and rotor cores, and the characteristics of additional iron loss caused by harmonic fields. By the comparison of predicted and measured no-load iron loss under different supply voltages and switching frequencies, the proposed model and the analysis results are validated.
Autors: Zhao Haisen;Zhang Dongdong;Wang Yilong;Zhan Yang;Xu Guorui;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2018, volume: 54, issue:1, pages: 832 - 840
Publisher: IEEE
 
» Piezoelectric Rainfall Energy Harvester Performance by an Advanced Arduino-Based Measuring System
Abstract:
This paper presents the performances of rainfall energy harvesting through the use of a piezoelectric transducer and an Arduino-based measuring system. Different studies agree on the possibility of generating electricity from rainfall, but to date, a study on measuring the quantity of energy produced during rainfall is still missing. The present study begins with results obtained from laboratory researchers using piezoelectric transducers and oscilloscopes, finalized to measure the energy produced from a single raindrop, and concludes with an ad hoc Arduino-based measuring system, aimed to measure the actual amount of electrical energy produced by a piezoelectric transducer that is exposed to rainfall of variable durations.
Autors: Gianluca Acciari;Massimo Caruso;Rosario Miceli;Luca Riggi;Pietro Romano;Giuseppe Schettino;Fabio Viola;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2018, volume: 54, issue:1, pages: 458 - 468
Publisher: IEEE
 
» Pilot Reuse Among D2D Users in D2D Underlaid Massive MIMO Systems
Abstract:
In a device-to-device (D2D) underlaid massive multiple-input multiple-output system, D2D transmitters reuse the uplink spectrum of cellular users (CUs), leading to cochannel interference. To decrease pilot overhead, we assume pilot reuse (PR) among D2D pairs. We first derive the minimum-mean-square-error estimation of all channels and give a lower bound on the ergodic achievable rate of both cellular and D2D links. To mitigate pilot contamination caused by PR, we then propose a pilot scheduling and pilot power control algorithm based on the criterion of minimizing the sum mean-square-error of channel estimation of D2D links. We show that, with an appropriate PR ratio and a well-designed pilot scheduling scheme, each D2D transmitter could transmit its pilot with maximum power. In addition, we also maximize the sum rate of all D2D links while guaranteeing the quality of service of CUs, and develop an iterative algorithm to obtain a suboptimal solution. Simulation results show that the effect of pilot contamination can be greatly decreased by the proposed pilot scheduling algorithm, and the PR scheme provides significant performance gains over the conventional orthogonal training scheme in terms of system spectral efficiency.
Autors: Hao Xu;Wei Xu;Zhaohui Yang;Jianfeng Shi;Ming Chen;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2018, volume: 67, issue:1, pages: 467 - 482
Publisher: IEEE
 
» Placement of Fault Current Limiters in a Power System Through a Two-Stage Optimization Approach
Abstract:
With the sustainable growth in the number of new power plants and scale of transmission systems, the probability of the current exceeding the short-circuit rating of circuit breakers increases. A fault current limiter (FCL), which can be used to reduce current surges, has attracted considerable attention from utilities. However, the appropriate placement of FCLs in a power system for obtaining the most effective cost-to-benefit solution is crucial. This paper proposes a two-stage placement approach, where Stage I combines the hierarchical fuzzy logic decision (HFLD) method and Hashing-integrated generic algorithm (HIGA). The HFLD method is used for sorting feasible solutions, and the HIGA determines an optimal FCL placement in the reduced search space. Particle swarm optimization is then employed in Stage II for optimizing the FCL parameters. To verify the effectiveness of the proposed approach in solving the optimal FCL placement problem, the method is verified using the IEEE 30-bus system and system of a manufacturing factory in Taiwan. The numerical results show that the proposed method achieves a favorable solution in a short time with fewer placements of FCLs.
Autors: Hong-Tzer Yang;Wen-Jun Tang;Piotr Roman Lubicki;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jan 2018, volume: 33, issue:1, pages: 131 - 140
Publisher: IEEE
 
» Planar UWB MIMO Antenna With Pattern Diversity and Isolation Improvement for Mobile Platform Based on the Theory of Characteristic Modes
Abstract:
This communication presents a planar ultra-wideband multi-input multi-output antenna with pattern diversity and isolation improvement based on the theory of characteristic modes. The proposed antenna (for new-generation wireless mobile terminals) consists of two ultra-wideband antenna elements—a compact quarter loop and a circular planar monopole located on the opposite edges of a rectangular ground plane. These two antenna elements are able to excite different modes in the ground plane and thus realize the desired diverse radiation patterns and high isolation without any additional decoupling structures. The experimental results show that both antenna elements are ultra-wideband with impedance bandwidths (return losses more than 6 dB for the quarter-loop antenna and more than 10 dB for the circular planar monopole antenna) of 130% (2–9.5 GHz). The isolation is over 20 dB with a peak value of 50 dB. The realized gains are above 1.5 dBi. The total efficiencies are above 70%. The envelope correlation coefficient is less than 0.03 assuming that the antenna operates in an isotropic channel.
Autors: Xing Zhao;Swee Ping Yeo;Ling Chuen Ong;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2018, volume: 66, issue:1, pages: 420 - 425
Publisher: IEEE
 
» Planarization, Fabrication, and Characterization of Three-Dimensional Magnetic Field Sensors
Abstract:
Nanomagnetism deals with magnetic phenomena in nanoscale structures, involving processes at the atomic level. Magnetic sensors, which exhibit the surprising giant magnetoresistance (GMR) effect, are some of the first real applications of nanotechnology, and have become very important in the last two decades. In addition, high-performance magnetoresistance (MR) measurement is a critical technique in modern electrical applications, including electronic compasses, aviation navigation, motion tracking, noncontact current sensing, rotation sensing, and vehicle detection. Both GMR and tunneling magnetoresistance (TMR) sensors have been used in the state-of-art electronic compasses. A new planar design layout of a vector magnetometer is proposed in this report. It can sense variations in three-dimensional (3-D) magnetic fields. The planarization of a vector magnetometer is carried out with consideration of materials, magnetic schematics, as well as transducer circuit designs. The optimization of an advanced magnetic material for use in GMR and TMR sensors and its planarization in a 3-D design are crucial practical issues. This paper presents an overview of the planarization of vector magnetometers and the development of its applications. It focuses on recent works, covers an analytic model of magnetoresistive sensors, and methods of thin film fabrication. It also addresses the planar vector magnetometer with a flux-guide, the chopping technique, and techniques for microfabrication of substrates. Planarization in magnetic sensors will become increasingly exploited as nanomagnetism grows in importance.
Autors: Van Su Luong;Yu-Hsin Su;Chih-Cheng Lu;Jen-Tzong Jeng;Jen-Hwa Hsu;Ming-Han Liao;Jong-Ching Wu;Meng-Huang Lai;Ching-Ray Chang;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jan 2018, volume: 17, issue:1, pages: 11 - 25
Publisher: IEEE
 
» Planning and Control for Collision-Free Cooperative Aerial Transportation
Abstract:
This paper presents planning and control synthesis for multiple aerial manipulators to transport a common object. Each aerial manipulator that consists of a hexacopter and a two-degree-of-freedom robotic arm is controlled by an augmented adaptive sliding mode controller based on a closed-chain robot dynamics. We propose a motion planning algorithm by exploiting rapidly exploring random tree star (RRT*) and dynamic movement primitives (DMPs). The desired path for each aerial manipulator is obtained by using RRT* with Bezier curve, which is designed to handle environmental obstacles, such as buildings or equipments. During aerial transportation, to avoid unknown obstacle, DMPs modify the trajectory based on the virtual leader-follower structure. By the combination of RRT* and DMPs, the cooperative aerial manipulators can carry a common object to keep reducing the interaction force between multiple robots while avoiding an obstacle in the unstructured environment. To validate the proposed planning and control synthesis, two experiments with multiple custom-made aerial manipulators are presented, which involve user-guided trajectory and RRT*-planned trajectory tracking in unstructured environments.
Autors: Hyeonbeom Lee;Hyoin Kim;H. Jin Kim;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jan 2018, volume: 15, issue:1, pages: 189 - 201
Publisher: IEEE
 
» Plastic Strain Determination With Nonlinear Ultrasonic Waves Using In Situ Integrated Piezoelectric Ultrasonic Transducers
Abstract:
The detection of plastic deformation of metallic alloy materials with second-harmonic Rayleigh ultrasonic wave is first investigated using direct-write piezoelectric ultrasonic transducers, in which piezoelectric poly(vinylidenefluoride/ trifluoroethylene) [P(VDF/TrFE)] polymer coatings and electrodes are directly deposited, processed, and patterned on the alloy to be evaluated. Rayleigh ultrasonic signals, generated by the direct-write transducers on titanium alloy specimens, are characterized by a laser scanning vibrometer. The results show that acoustic nonlinearity increases with plastic strain, and an increase of ~40% in the acoustic nonlinearity corresponding to a plastic strain of 5.1%. The measurement data and technical features with the use of the direct-write transducers are compared with the conventional discrete angle beam piezoelectric transducer. The results and analyses show that compared with the conventional discrete angle beam piezoelectric transducers, implementation of the direct-write piezoelectric transducers has significant technical advantages and is promising for applications in determining nonlinear ultrasonic waves and plastic strain of structural materials.
Autors: Shifeng Guo;Shuting Chen;Lei Zhang;Yi Fan Chen;Kui Yao;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Jan 2018, volume: 65, issue:1, pages: 95 - 101
Publisher: IEEE
 
» PLRC-FDTD Modeling of General GSTC-Based Dispersive Bianisotropic Metasurfaces
Abstract:
A general bianaisotropic metasurface represented by a generalized sheet transition condition is modeled by the finite-difference time-domain (FDTD) method. The dispersive susceptibilities of the metasurface are approximated by FDTD-compatible rational functions which are incorporated in the update equations by the piecewise linear recursive convolution technique. Compared to the existing methods, the proposed technique requires less arithmetic operations. The method is verified by comparing the results with those of the finite-difference frequency-domain method through simulation of wave propagation in five test cases: generalized refraction metasurface, polarization rotator, Bessel beam generator, orbital angular momentum multiplexer, and reflectionless omega-type metasurface.
Autors: Keyhan Hosseini;Zahra Atlasbaf;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2018, volume: 66, issue:1, pages: 262 - 270
Publisher: IEEE
 
» PMU-Based Estimation of Dynamic State Jacobian Matrix and Dynamic System State Matrix in Ambient Conditions
Abstract:
In this paper, a hybrid measurement- and model-based method is proposed which can estimate the dynamic state Jacobian matrix and the dynamic system state matrix in near real time utilizing statistical properties extracted from PMU measurements. The proposed method can be used to detect and identify network topology changes that have not been reflected in an assumed network model. Additionally, an application of the estimated system state matrix in online dynamic stability monitoring is presented.
Autors: Xiaozhe Wang;Janusz W. Bialek;Konstantin Turitsyn;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jan 2018, volume: 33, issue:1, pages: 681 - 690
Publisher: IEEE
 
» Podium: Ranking Data Using Mixed-Initiative Visual Analytics
Abstract:
People often rank and order data points as a vital part of making decisions. Multi-attribute ranking systems are a common tool used to make these data-driven decisions. Such systems often take the form of a table-based visualization in which users assign weights to the attributes representing the quantifiable importance of each attribute to a decision, which the system then uses to compute a ranking of the data. However, these systems assume that users are able to quantify their conceptual understanding of how important particular attributes are to a decision. This is not always easy or even possible for users to do. Rather, people often have a more holistic understanding of the data. They form opinions that data point A is better than data point B but do not necessarily know which attributes are important. To address these challenges, we present a visual analytic application to help people rank multi-variate data points. We developed a prototype system, Podium, that allows users to drag rows in the table to rank order data points based on their perception of the relative value of the data. Podium then infers a weighting model using Ranking SVM that satisfies the user's data preferences as closely as possible. Whereas past systems help users understand the relationships between data points based on changes to attribute weights, our approach helps users to understand the attributes that might inform their understanding of the data. We present two usage scenarios to describe some of the potential uses of our proposed technique: (1) understanding which attributes contribute to a user's subjective preferences for data, and (2) deconstructing attributes of importance for existing rankings. Our proposed approach makes powerful machine learning techniques more usable to those who may not have expertise in these areas.
Autors: Emily Wall;Subhajit Das;Ravish Chawla;Bharath Kalidindi;Eli T. Brown;Alex Endert;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Publication date: Jan 2018, volume: 24, issue:1, pages: 288 - 297
Publisher: IEEE
 
» Point-to-Set Distance Metric Learning on Deep Representations for Visual Tracking
Abstract:
For autonomous driving application, a car shall be able to track objects in the scene in order to estimate where and how they will move such that the tracker embedded in the car can efficiently alert the car for effective collision-avoidance. Traditional discriminative object tracking methods usually train a binary classifier via a support vector machine (SVM) scheme to distinguish the target from its background. Despite demonstrated success, the performance of the SVM-based trackers is limited because the classification is carried out only depending on support vectors (SVs) but the target’s dynamic appearance may look similar to the training samples that have not been selected as SVs, especially when the training samples are not linearly classifiable. In such cases, the tracker may drift to the background and fail to track the target eventually. To address this problem, in this paper, we propose to integrate the point-to-set/ image-to-imageSet distance metric learning (DML) into visual tracking tasks and take full advantage of all the training samples when determining the best target candidate. The point-to-set DML is conducted on convolutional neural network features of the training data extracted from the starting frames. When a new frame comes, target candidates are first projected to the common subspace using the learned mapping functions, and then the candidate having the minimal distance to the target template sets is selected as the tracking result. Extensive experimental results show that even without model update the proposed method is able to achieve favorable performance on challenging image sequences compared with several state-of-the-art trackers.
Autors: Shengping Zhang;Yuankai Qi;Feng Jiang;Xiangyuan Lan;Pong C. Yuen;Huiyu Zhou;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Jan 2018, volume: 19, issue:1, pages: 187 - 198
Publisher: IEEE
 
» Pokemon GO: Where VR and AR Have Gone Since Its Inception
Abstract:
Augmented reality (AR), virtual reality (VR), and mixed reality (MR) are the technologies of the future. At the same time, they remain a bit of a mystery to many people.
Autors: Melina Druga;
Appeared in: IEEE Potentials
Publication date: Jan 2018, volume: 37, issue:1, pages: 23 - 26
Publisher: IEEE
 
» Polarimetric Coherence Pattern: A Visualization and Characterization Tool for PolSAR Data Investigation
Abstract:
Polarimetric coherence, which has the potential to reveal physical properties of scatterers, is an important source for polarimetric synthetic aperture radar (PolSAR) data investigation. Target structure and orientation relative to the PolSAR illumination direction are key factors affecting the polarimetric coherence degree. The relative orientation between a sensor and a target can be adjusted using the rotating processing along the radar’s line of sight. The main idea of this paper is to extend the traditional polarimetric coherence at a given rotation state ( to the rotation domain ( along the radar’s line of sight for hidden information exploration. A visualization and characterization tool named as a polarimetric coherence pattern for two arbitrary polarization channels is proposed and developed. This interpretation tool is able to view the variation of polarimetric coherence in the rotation domain containing rich orientation diversity information which is seldom considered. A set of characterization features are derived to completely describe a polarimetric coherence pattern thereafter. Experimental studies with unmanned aerial vehicle SAR (UAVSAR) PolSAR data over crop areas have validated that polarimetric coherence patterns vary in terms of polarization combinations and crop types. The proposed characterization features show good potential to differentiate polarimetric responses from different land covers. Furthermore, a classification scheme combining the selected proposed features and the commonly used roll-invariant features is developed for quantitative and application investigation. Comparison studies with both UAVSAR and Airborne SAR (AIRSAR) data clearly demonstrate the superiority of the proposed classification to the conventi- nal classification with only roll-invariant features. The overall classification accuracies for the seven and eleven land covers of UAVSAR and AIRSAR data are, respectively, increased from 90.21% and 93.87% to 95.12% and 94.63% by the proposed classification scheme. This paper also demonstrates the importance of and potential for utilizing the complementary advantages of roll-invariant features and the proposed roll-variant features.
Autors: Si-Wei Chen;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jan 2018, volume: 56, issue:1, pages: 286 - 297
Publisher: IEEE
 
» Polarization-Maintaining Hollow-Core Photonic Bandgap Few-Mode Fiber in Terahertz Regime
Abstract:
We propose a terahertz (THz) hollow-core photonic bandgap fiber (HC-PBGF) supporting few-mode operation with large birefringence. The periodic arrangement of square lattice with round corners in fiber cladding offers bandgap guidance. Numerical simulation indicates that a 21-cell HC-PBGF could support six vector modes in the bandgap. Characteristics of guided modes are comprehensively investigated, suggesting modal confinement loss of the order of 10−3 cm−1, group velocity dispersion under 1 psTHz−1cm−1, and modal birefringence higher than 10−4 for all modes at around 0.92 THz. Moreover, 24-cell and 32-cell HC-PBGFs are discussed to explore the influence of HC geometry on guided mode number and modal birefringence.
Autors: Han Xiao;Haisu Li;Guobin Ren;Yue Dong;Shiying Xiao;Shuisheng Jian;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2018, volume: 30, issue:2, pages: 185 - 188
Publisher: IEEE
 
» Power and Bandwidth Allocation for Cognitive Heterogeneous Multi-Homing Networks
Abstract:
In this paper, an uplink power and bandwidth allocation problem for multiple services with multi-homing technology is formulated for cognitive heterogeneous networks. The joint power and bandwidth allocation with multiple services is subject to constraints in system available bandwidth, proportional fairness transmission rate for non-real-time secondary mobile terminals (MTs), minimum required transmission rate for real-time secondary MTs, interference power for primary base station, and total power consumption for each secondary MT. The joint power and bandwidth allocation problem with multiple services based on risk-return model is formulated as a bargaining game framework, first. Then, an optimal power and bandwidth allocation algorithm utilizing a dual decomposition method is proposed to obtain Nash bargaining solution. Finally, a heuristic algorithm is proposed to reduce computational complexity. Simulation results demonstrate the optimal and heuristic algorithms not only improve the spectrum efficiency, but also guarantee the fairness for secondary MTs with non-real-time service.
Autors: Lei Xu;Arumugam Nallanathan;Jian Yang;Wenhe Liao;
Appeared in: IEEE Transactions on Communications
Publication date: Jan 2018, volume: 66, issue:1, pages: 394 - 403
Publisher: IEEE
 
» Power Delivery Network Benchmarking for Interposer and Bridge-Chip-Based 2.5-D Integration
Abstract:
In this letter, a power delivery network (PDN) modeling framework for emerging heterogeneous 2.5-D integration platforms is presented. The framework is validated using IBM power grid benchmarks, and maximum relative errors of less than 7.29% and 0.67% for IR-drop and transient noise are shown, respectively. Next, the framework is used to evaluate interposer and bridge-chip-based 2.5-D integration platforms. The simulation results show that an interposer with dense power/ground grids and microbumps can suppress power supply noise (PSN) by a small margin. In bridge-chip-based 2.5-D integration, under the assumption that the bridge-chips underneath the active dice block direct access to package power/ground planes, some PDN considerations are highlighted and evaluated. Using multiple bridge-chips and smaller overlap areas between the bridge-chips and the active dice, the worst case PSN in bridge-chip-based 2.5-D integration is minimally impacted.
Autors: Yang Zhang;Md Obaidul Hossen;Muhannad S. Bakir;
Appeared in: IEEE Electron Device Letters
Publication date: Jan 2018, volume: 39, issue:1, pages: 99 - 102
Publisher: IEEE
 
» Power Quality Characteristics of a Multilevel Current Source With Optimal Predictive Scheme From More-Electric-Aircraft Perspective
Abstract:
Revolutionary design power architectures into electric aircraft system are being actively discussed to cope with the issues of a present state-of-the-art technology. The two demanding objectives in more-electric-aircraft (MEA) concept are power quality enhancement and increased level of redundancy despite of higher on-board power supply requirement throughout aircraft operation. In addressing the open challenges, this study outlines an operational characteristics of a three-phase multilevel shunt active filter (SAF) deployed for distribution power system in emerging MEA. The introduced shunt active filter is based on modular multilevel converter configuration for harmonic-current compensation purposes. On this foundation, a current control strategy for SAF is designed with a finite-control-set model predictive control technique. The developed solution provides several merits into aircraft electrical network as easy implementation on embedded platforms, controllable feature with a wide range of current frequencies, producing exact current harmonic replica onto the supply side over a given prediction horizon, and modular design with redundancy functionality. Dedicated predictive control system helps to better execution-time efficiency together with low sensitivity over the constraints imposed upon the optimization formulation through an integrated perturbation analysis and sequential quadratic programming solver. Simulation and experimental verifications for the three-phase four-level shunt active power filter are discussed, where robust behavior of handling harmonic currents with respect to the supply impedance and fundamental frequency variations is achieved, when the harmonic distortion levels fulfill the IEEE Standard 519 recommendations.
Autors: Hamed Nademi;Rolando Burgos;Zareh Soghomonian;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2018, volume: 67, issue:1, pages: 160 - 170
Publisher: IEEE
 
» Power Quality Improvement of Grid-Connected DC Microgrids Using Repetitive Learning-Based PLL Under Abnormal Grid Conditions
Abstract:
This paper proposes a repetitive learning-based phase locked loop (RLPLL) to improve power quality of the grid-connected dc microgrids under distorted grid voltage in a weak grid. The harmonic component present in grid current in a high impedance network amplifies the distortion in voltage, which often leads to instability. Since the behavior of the conventional synchronous reference frame PLL (SRF-PLL) varies, owing to the proportional-integral gains constrained to harmonic rejection bandwidth ultimately leading to a sluggish response. However, RLPLL accommodates this limitation with a comparable dynamic performance and enhanced harmonic attenuation properties. This has been achieved by using a Lyapunov-based approach for harmonic estimation, which facilitates the periodicity and boundedness of the harmonic component to obtain an adaptive learning-based update. To deal with the computational burden, this paper also provides a low-computing alternative model of the proposed strategy. The dynamic response of RLPLL along with a comparative analysis with SRF-PLL is governed by many events directly affecting the dc voltage, which is critical for the operation of dc microgrids. Its performance is validated under different scenarios in a 1-kVA field programmable gate array-based experimental setup.
Autors: Subham Sahoo;Surya Prakash;Sukumar Mishra;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2018, volume: 54, issue:1, pages: 82 - 90
Publisher: IEEE
 
» Power Quality Investigation in Ceramic Insulator
Abstract:
This paper presents a new method for the detection of high-voltage flashover using the power quality parameters in the insulator testing industries at a remote location from the test rig. In ceramic insulator industries, it is mandatory to test each insulator at manufacturing stage for high-voltage power frequency flashover/withstand test. The flashover is visually detected by the operator in insulator industries. Therefore, an operator has to be physically present close to the testing rig for the detection of flashover, which is very dangerous for the life. The proposed “high-voltage flashover detector” detects the flashover in insulators without using any quantity required to be measured from the high-voltage side of the test rig. The proposed scheme provides an improved flashover detection system, which detects the flashover without its visual inspection. The flashover phenomenon is reliably detected at some distant location from the test rig using power quality parameters of the system. The detailed power quality analysis of high-voltage ceramic insulator industries during power frequency flashover test and lightning impulse test based on experimental investigation is also reported here. Initially, a prototype of the new method for detection of high-voltage flashover is designed and implemented for flashover detection in insulator industries and in test laboratories. This scheme may also be extended to detect the fault on hot line with required modifications.
Autors: Ujjwal Kumar Kalla;Rakhi Suthar;Kunal Sharma;Bhim Singh;Jaiwin Ghotia;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2018, volume: 54, issue:1, pages: 121 - 134
Publisher: IEEE
 
» Power Split Strategy Optimization of a Plug-in Parallel Hybrid Electric Vehicle
Abstract:
Hybrid electric vehicles (HEV), plug-in HEV (PHEV) need an energy management system (EMS) to ensure good fuel economy while maintaining battery state-of-charge (SOC) within a safe range. The EMS is in charge of the power split decision between the engine and the electrical motor. For a PHEV, the optimal power split scenario will depend on the driving cycle, initial SOC, and trip length. Heavy computation and accurate knowledge of the future trip are required to find the optimal power split control and this represents a significant difficulty for the development of an EMS. The aim of this paper is to propose a genetic algorithm (GA) that optimizes the power split control parameters for a given driving cycle in a relatively short computation time, thus, overcoming the problem of heavy computation. The methodology consists in 1) defining the control laws and their associated control parameters based on the observation of optimality obtained by dynamic programming; and 2) developing a GA that will be able to compute the near-optimal values of these parameters in a short time and for a given driving cycle. It is demonstrated that the GA provides short computational burden and near-optimality for a wide variety of driving cycles. It then offers a promising tool for a future real-time implementation.
Autors: Nicolas Denis;Maxime R. Dubois;João Pedro F. Trovão;Alain Desrochers;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2018, volume: 67, issue:1, pages: 315 - 326
Publisher: IEEE
 
» Power Takeoff Optimization to Maximize Wave Energy Conversions for Oscillating Water Column Devices
Abstract:
This paper presents an investigation on how to optimize the power takeoffs (PTOs) to maximize the mean wave energy conversion from seas for floating oscillating water column (OWC) devices. For this purpose, the linear air turbine PTOs are first analytically optimized to maximize the mean energy conversion for regular waves, based on which a simple and fast-turnaround assessment method is proposed to optimize the linear PTO damping coefficient for maximizing the mean energy conversion for the given sea states. Further on, the focus is on how we can reliably assess the maximized mean wave energy conversions if the OWCs are equipped with nonlinear air-turbine PTOs, as frequently seen in practical OWC plants. Conventionally, the time-consuming time-domain analysis is employed for searching the optimized nonlinear damping coefficients which may be both wave-height- and wave-period-dependent for the given sea state. This may not be suitable in the early design stages of the device when many different options may be compared and checked for optimizing the device itself. As such, a reliable fast-turnaround assessment is very desirable for the device performance and for the assessment of energy conversion for the sea states in the deployment site. From the examples in the study, it is shown that the OWC wave energy converters with the optimized linear PTOs have the same energy capture capacities as those with optimized nonlinear PTOs. As such, it can be suggested that the OWC wave energy capture capacity can be analyzed using the fast-turnaround frequency-domain analysis, regardless of whether the linear or nonlinear PTO is used in the wave energy converter.
Autors: Wanan Sheng;Anthony Lewis;
Appeared in: IEEE Journal of Oceanic Engineering
Publication date: Jan 2018, volume: 43, issue:1, pages: 36 - 47
Publisher: IEEE
 
» Power to the People?: What It Means to the Changing Energy Landscape [In My View]
Abstract:
Autors: Gerd Schonwalder;
Appeared in: IEEE Power and Energy Magazine
Publication date: Jan 2018, volume: 16, issue:1, pages: 76 - 72
Publisher: IEEE
 
» PPC: Popularity Prediction Caching in ICN
Abstract:
Thriving future network conceives embedding the ubiquitous in-network caching. The fine-grained cache behavior reveals an intimate relationship among contents in the same stream—sequenced contents have similar cache behavior. This letter presents a novel cache replacement method named popularity prediction caching (PPC) for chunk-level cache by discovering the relevance among video chunks in information centric network from the perspective of user watching behavior. PPC predicts and caches the future most popular chunks and evicts those with least future popularity in a linear complexity. Simulations in a GEANT model show that PPC outperforms cache policy based on content popularity, least recently used, least frequently used, and first in first out.
Autors: Yuanzun Zhang;Xiaobin Tan;Weiping Li;
Appeared in: IEEE Communications Letters
Publication date: Jan 2018, volume: 22, issue:1, pages: 5 - 8
Publisher: IEEE
 
» Practical Superdirectivity With Resonant Screened Apertures Motivated by a Poynting Streamlines Analysis
Abstract:
Fundamental limits on the degree of practical achievable superdirectivity for antennas include narrow bandwidth, large antenna loss, and sensitivity to excitation and fabrication errors. Superdirective antennas are commonly considered as transmitters, but thinking of the antenna as a receiver may help to understand and overcome some of these limits on practical superdirectivity. We directly model a superdirective antenna in receive mode by calculating streamlines of Poynting vector field near the receiving antennas. Superdirectivity is achieved by expanding the shape of the effective area beyond the antenna physical aperture area. The degree of superdirectivity is parameterized by an effective area expansion distance. The theory predicts that superdirectivity is practical for electrically small and middle size antennas and electrically large antennas with a large aspect ratio. With this motivation, a superdirective horn antenna with resonant screen structure in front of the antenna aperture is designed and fabricated. The superdirective horn achieves a measured antenna efficiency of 115% over a reasonable bandwidth and with moderate sensitivity to fabrication errors.
Autors: Junming Diao;Karl F. Warnick;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2018, volume: 66, issue:1, pages: 432 - 437
Publisher: IEEE
 
» Precoded Index Modulation for Multi-Input Multi-Output OFDM
Abstract:
Index modulated orthogonal frequency division multiplexing (IM-OFDM) is a novel multicarrier transmission scheme, which provides considerable performance improvement compared with classical OFDM by conveying information via the active subcarrier indices in conjugation with the constellation symbols. In this paper, we extend the idea of IM-OFDM to multi-input multi-output (MIMO) systems and propose precoded MIMO-OFDM (PIM-MIMO-OFDM). Based on the channel state information at the transmitter, PIM-MIMO-OFDM selects the active elements of the receiver-side space-frequency subblocks via linear precoding. The spectral efficiency enhancement method of in-phase/quadrature index modulation is also employed to construct PIM-MIMO-OFDM with in-phase quadrature modulation by selecting the active space-frequency elements in the in-phase and quadrature components of the constellation symbol. Thanks to the carefully designed precoding, the co-channel interference among received antennas can be completely eliminated. Consequently, low-complexity maximum likelihood and suboptimal detectors are devised with linear detection complexity. Both analytical and numerical results show that, with the help of precoding, PIM-MIMO-OFDM can achieve better bit error rateperformance than traditional precoded MIMO-OFDM (P-MIMO-OFDM) in various system configurations. In addition, the spectral efficiency can be also enhanced compared with the P-MIMO-OFDM under certain configurations.
Autors: Shijian Gao;Meng Zhang;Xiang Cheng;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2018, volume: 17, issue:1, pages: 17 - 28
Publisher: IEEE
 
» Predicting Locations of High-Risk Plaques in Coronary Arteries in Patients Receiving Statin Therapy
Abstract:
Features of high-risk coronary artery plaques prone to major adverse cardiac events (MACE) were identified by intravascular ultrasound (IVUS) virtual histology (VH). These plaque features are: thin-cap fibroatheroma (TCFA), plaque burden PB ≥ 70%, or minimal luminal area MLA ≤ 4 mm2. Identification of arterial locations likely to later develop such high-risk plaques may help prevent MACE. We report a machine learning method for prediction of future high-risk coronary plaque locations and types in patients under statin therapy. Sixty-one patients with stable angina on statin therapy underwent baseline and one-year follow-up VH-IVUS non-culprit vessel examinations followed by quantitative image analysis. For each segmented and registered VH-IVUS frame pair (), location-specific ( mm) vascular features and demographic information at baseline were identified. Seven independent support vector machine classifiers with seven different feature subsets were trained to predict high-risk plaque types one year later. A leave-one-patient-out cross-validation was used to evaluate the prediction power of different feature subsets. The experimental results showed that our machine learning method predicted future TCFA with correctness of 85.9%, 81.7%, and 77.0% (G-mean) for baseline plaque phenotypes of TCFA, thick-cap fibroatheroma, and non-fibroatheroma, respectively. For predicting PB ≥ 70%, correctness was 80.8% for baseline PB ≥ 70% and 85.6% for 50% ≤ PB < 70%. Accuracy of predicted MLA ≤- 4 mm2 was 81.6% for baseline MLA ≤ 4 mm2 and 80.2% for 4 mm2 < MLA ≤ 6 mm2. Location-specific prediction of future high-risk coronary artery plaques is feasible through machine learning using focal vascular features and demographic variables. Our approach outperforms previously reported results and shows the importance of local factors on high-risk coronary artery plaque development.
Autors: Ling Zhang;Andreas Wahle;Zhi Chen;John J. Lopez;Tomas Kovarnik;Milan Sonka;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jan 2018, volume: 37, issue:1, pages: 151 - 161
Publisher: IEEE
 
» Prediction of Compression Ratio for DCT-Based Coders With Application to Remote Sensing Images
Abstract:
A problem of predicting compression ratio (CR) for lossy image compression methods based on discrete cosine transform (DCT) is considered for remote sensing imaging as a main target application. We demonstrate that the noise presence in images leads to specific requirements to lossy image compression as well as to criteria used, and ways to meet these requirements. In particular, it is often desired to compress images in the neighborhood of optimal operation point (OOP) where a compressed image might be closer to the corresponding noise-free one compared to noisy (original, uncompressed) counterpart. In this paper, first, we consider a problem of predicting CR for compressing noisy images in OOP neighborhood. Several statistical parameters calculated in DCT domain in 8 × 8 pixel blocks are used for this. The factors that influence a prediction accuracy and the ways to improve this accuracy are discussed. Next, we show that there is a statistical parameter that does not require any a priori information on noise properties, and that can be used to predict CR with a high accuracy without any necessity to apply multiple image compression/decompression procedures. The proposed methods are thoroughly tested for two DCT-based image coders applied to component-wise lossy compression of hyperspectral data. Finally, a modification of the prediction approach for 3-D compression of multichannel images is proposed.
Autors: Alexander N. Zemliachenko;Ruslan A. Kozhemiakin;Sergey K. Abramov;Vladimir V. Lukin;Benoît Vozel;Kacem Chehdi;Karen O. Egiazarian;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Jan 2018, volume: 11, issue:1, pages: 257 - 270
Publisher: IEEE
 
» Prediction of Moisture Loss in Withering Process of Tea Manufacturing Using Artificial Neural Network
Abstract:
The first and foremost process in tea manufacturing, withering, is the foundation for producing good quality. Moisture plays an important role in the manufacturing process of tea to get the desired quality. In this paper, a novel in situ instrumentation technique is proposed and validated experimentally for prediction of moisture loss (ML) in the withering process. In the proposed technique, ML is predicted based on the inlet and the outlet relative humidity (RH) and temperature during the process of withering. Network capable smart sensor nodes are developed for the measurement of RH and temperature at the inlet and outlet of the withering trough. Architecture of the nodes and network is described. A scaled-down prototype of an enclosed trough is developed to perform withering of tea leaves. Based on the data measured by the system, ML is predicted by using artificial neural network. Nonlinear autoregressive model with exogenous inputs is used for predicting the ML. The predicted ML is compared with the actual amount of ML measured by weight loss. A total of nine experiments are conducted for nine batches of tea leaves. The data collection, their analysis and results are reported in this paper. The observed result shows a good agreement between the predicted and actual ML. The maximum mean error in prediction is −3.6%.
Autors: Nipan Das;Kunjalata Kalita;P K Boruah;Utpal Sarma;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2018, volume: 67, issue:1, pages: 175 - 184
Publisher: IEEE
 
» Preface: Message from the VIS Paper Chairs and Guest Editors
Abstract:
EditorsThis January 2018 issue of the IEEE Transactions on Visualization and Computer Graphics contains the proceedings of IEEE VIS 2017, held during 1-6 October 2017. In 2017, IEEE VIS returns to the city of Phoenix, AZ, USA, for the conference's 28th year. The conference will be held at the Hyatt Regency Phoenix hotel. VIS consists of three conferences, held concurrently: the IEEE Visual Analytics Science and Technology Conference (VAST 2017), the IEEE Information Visualization Conference (InfoVis 2017), and the IEEE Scientific Visualization Conference (SciVis 2017). Information on the paper review process is provided along with an overview of each conference.
Autors: Tim Dwyer;Niklas Elmqvist;Brian Fisher;Steve Franconeri;Ingrid Hotz;Robert M. Mike Kirby;Shixia Liu;Tobias Schreck;Xiaoru Yuan;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Publication date: Jan 2018, volume: 24, issue:1, pages: xi - xv
Publisher: IEEE
 
» Prefetch-Based Energy Optimization on Smartphones
Abstract:
Cellular network enables pervasive data access, but it also increases the power consumption of smartphones due to the long tail problem, where the cellular interface has to stay in the high-power state for some time after each data transmission. To reduce the tail energy, data that will be used in the future can be prefetched. However, prefetching unnecessary data may waste energy, and this problem becomes worse when the network quality is poor. In this paper, we generalize and formulate the prefetch-based energy optimization problem, where the goal is to find a prefetching schedule that minimizes the energy consumption of the data transmissions under the current network condition. To solve this nonlinear optimization problem, we first propose a greedy algorithm, and then propose a discrete algorithm with better performance. We have implemented and evaluated the proposed algorithms in two apps: in-app advertising and mobile video streaming. Evaluation results show that the proposed algorithms can significantly reduce the energy consumption.
Autors: Yi Yang;Guohong Cao;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2018, volume: 17, issue:1, pages: 693 - 706
Publisher: IEEE
 
» Preparing to Witness a Multimegawatt Motor and Adjustable Speed Drive Acceptance Test–The Basics
Abstract:
Adjustable speed drive (ASD) and motors, if selected as a prime mover for compressors, pumps, extruders, etc., can provide various electromechanical benefits to its operators and stakeholders. Their benefits and application considerations have been well documented in past papers and tutorials. However, a successful installation of a multimegawatt motor and ASD system requires detailed application, engineering, manufacturing, testing, and installation considerations. Many times testing is requested by the operator and/or consultant, but navigating the types of tests available, test procedures, plans, and how they comply with appropriate standards is often not fully understood. This can lead to surprises, shipment delays, price adders, and ultimately the equipment itself not being in compliance with the stated project objectives. This paper attempts to address the factory acceptance testing phase of a medium voltage motor and ASD system whether procured separately or as a package. Issues such as type of test selection, specifications, standards, preparation, acceptance criteria, and finally string testing will be covered. This paper serves as a guideline of how one can select, prepare, witness, and sign off on a medium voltage motor and ASD test.
Autors: Manish Verma;Izhak (Ike) Grinbaum;John Arnold;James Nanney;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2018, volume: 54, issue:1, pages: 873 - 882
Publisher: IEEE
 
» Priming and Anchoring Effects in Visualization
Abstract:
We investigate priming and anchoring effects on perceptual tasks in visualization. Priming or anchoring effects depict the phenomena that a stimulus might influence subsequent human judgments on a perceptual level, or on a cognitive level by providing a frame of reference. Using visual class separability in scatterplots as an example task, we performed a set of five studies to investigate the potential existence of priming and anchoring effects. Our findings show that—under certain circumstances—such effects indeed exist. In other words, humans judge class separability of the same scatterplot differently depending on the scatterplot(s) they have seen before. These findings inform future work on better understanding and more accurately modeling human perception of visual patterns.
Autors: André Calero Valdez;Martina Ziefle;Michael Sedlmair;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Publication date: Jan 2018, volume: 24, issue:1, pages: 584 - 594
Publisher: IEEE
 
» Printed Log-Periodic Monopole Array Antenna With a Simple Feeding Structure
Abstract:
A novel printed log-periodic monopole array (PLPMA) antenna is proposed and investigated. The antenna has advantages of easy design, wide bandwidth, and high gain. Compared with conventional printed log-periodic dipole array antennas, the antenna has a simpler feeding structure, and its monopole elements have smaller size and can be printed on a single side of the substrate. A PLPMA with 12 printed monopole elements is designed. A prototype of the antenna is fabricated using the standard printed circuit board process, and measured results are consistent with theoretical and simulated results. Measured results show that the design has a broad operation band from 8.4 to 14.6 GHz, in which the voltage standing-wave ratio is lower than 2.0 and the gain is high and stable with a variation from 6.5 to 9.5 dBi.
Autors: Xiaoshuai Wei;Juhua Liu;Yunliang Long;
Appeared in: IEEE Antennas and Wireless Propagation Letters
Publication date: Jan 2018, volume: 17, issue:1, pages: 58 - 61
Publisher: IEEE
 
» Privacy and Integrity Considerations in Hyperconnected Autonomous Vehicles
Abstract:
The rapid advances in technology can be witnessed in the emergence of cyber–physical systems that pertain to several domains of our society. In transportation, we see the emergence of self-driving vehicles that utilize a multitude of sensors and intelligent learning techniques to navigate autonomously. Such vehicles are complex cyber–physical systems that are mobile and due to their sensor and intrinsic intelligence are able to collect, analyze, and capitalize upon an unprecedented amount of fine-grained data, as well as collaborate in real time with multiple stakeholders. Although such rich data can play a key role in data-driven economies of scale, this raises questions with respect to privacy- and integrity-dependent scenarios. In this work, the feasibility of ensuring integrity, and hence safety, while preserving privacy in the emerging hyperconnected vehicle scenarios is discussed. An exemplary case study on real-time vehicle interactions pertaining to map updates exemplifies the combination of privacy-enhancing technologies with integrity-protecting mechanisms.
Autors: Stamatis Karnouskos;Florian Kerschbaum;
Appeared in: Proceedings of the IEEE
Publication date: Jan 2018, volume: 106, issue:1, pages: 160 - 170
Publisher: IEEE
 
» Probabilistic Forecast for Multiple Wind Farms Based on Regular Vine Copulas
Abstract:
The uncertain nature of wind power causes difficulties in power system operation scheduling. Probabilistic descriptions of the uncertainty have been studied for decades. However, probabilistic forecasts designed for the regional multiple wind farms are few. Although the traditional methods for the single wind farm can still be used, they have the limitations in capturing the spatial correlations among wind farms, and they are less robust when multivariate observations are not so complete. To improve the forecast quality in this case, we combine the multivariate distribution modeling and probabilistic forecasts in this paper. An advanced model—the regular vine copula, which can describe the wind farms’ dependence structure precisely and flexibly with various bivariate copulas as blocks, is used in this paper. Enough simulation data can be generated from the model, which can be easily used to form the conditional forecast distributions under multiple forecast conditions. A case of 10 wind farms in East China has been used to compare the proposed method with its competitors. The results showed the method's advantages of providing reliable and sharp forecast intervals, especially in the case with limited observations available.
Autors: Zhao Wang;Weisheng Wang;Chun Liu;Zheng Wang;Yunhe Hou;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jan 2018, volume: 33, issue:1, pages: 578 - 589
Publisher: IEEE
 
» Probabilistic Framework for Online Identification of Dynamic Behavior of Power Systems With Renewable Generation
Abstract:
The paper introduces a probabilistic framework for online identification of post fault dynamic behavior of power systems with renewable generation. The framework is based on decision trees and hierarchical clustering and incorporates uncertainties associated with network operating conditions, topology changes, faults, and renewable generation. In addition to identifying unstable generator groups, the developed clustering methodology also facilitates identification of the sequence in which the groups lose synchronism. The framework is illustrated on a modified version of the IEEE 68 bus test network incorporating significant portion of renewable generation.
Autors: Panagiotis N. Papadopoulos;Tingyan Guo;Jovica V. Milanović;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jan 2018, volume: 33, issue:1, pages: 45 - 54
Publisher: IEEE
 
» Probabilistic Threat Detection for Risk Management in Cyber-physical Medical Systems
Abstract:
Medical devices are complex cyber-physical systems incorporating emergent hardware and software components. However, this complexity leads to a wide attack surface posing security risks and vulnerabilities. Mitigation and management of such risks during premarket design and postmarket deployment are required. Dynamically mitigating threat potential in the presence of unknown vulnerabilities requires an adaptive risk-based scheme to assess the system’s state, a secure system architecture that can isolate hardware and software components, and design methods that can adaptively adjust the system’s topology based on risk changes. The essential complementary aspects during deployment are detecting, characterizing, and quantifying security threats. This article presents a dynamic risk management and mitigation approach based on probabilistic threat estimation. A smart-connected-pacemaker case study illustrates the approach. This article is part of a special issue on Software Safety and Security Risk Mitigation in Cyber-physical Systems.
Autors: Aakarsh Rao;Nadir Carreón;Roman Lysecky;Jerzy Rozenblit;
Appeared in: IEEE Software
Publication date: Jan 2018, volume: 35, issue:1, pages: 38 - 43
Publisher: IEEE
 
» Progressive Learning of Topic Modeling Parameters: A Visual Analytics Framework
Abstract:
Topic modeling algorithms are widely used to analyze the thematic composition of text corpora but remain difficult to interpret and adjust. Addressing these limitations, we present a modular visual analytics framework, tackling the understandability and adaptability of topic models through a user-driven reinforcement learning process which does not require a deep understanding of the underlying topic modeling algorithms. Given a document corpus, our approach initializes two algorithm configurations based on a parameter space analysis that enhances document separability. We abstract the model complexity in an interactive visual workspace for exploring the automatic matching results of two models, investigating topic summaries, analyzing parameter distributions, and reviewing documents. The main contribution of our work is an iterative decision-making technique in which users provide a document-based relevance feedback that allows the framework to converge to a user-endorsed topic distribution. We also report feedback from a two-stage study which shows that our technique results in topic model quality improvements on two independent measures.
Autors: Mennatallah El-Assady;Rita Sevastjanova;Fabian Sperrle;Daniel Keim;Christopher Collins;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Publication date: Jan 2018, volume: 24, issue:1, pages: 382 - 391
Publisher: IEEE
 
» Proton Irradiation Effects on AlGaN/GaN HEMTs With Different Isolation Methods
Abstract:
We evaluated the electrical characteristics of two different AlGaN/GaN high-electron mobility transistors (HEMTs) for the 5-MeV proton irradiation effects. The difference of the HEMTs originates from the isolation methods, such as mesa etching and nitrogen ion implantation. At a proton fluence of p/cm2, the saturation drain currents of two devices are reduced by 50% and 11% for the mesa etching and the nitrogen ion implantation, respectively. The displacement damages are believed to degrade the electrical characteristics of AlGaN/GaN HEMTs. AlGaN/GaN HEMTs with nitrogen ion implantation isolation show relatively higher radiation hardness than those with mesa etching isolation. The reason is that plasma etching easily damages the surface of mesa sidewall and causes more defects by proton irradiation.
Autors: Dong-Seok Kim;Jun-Hyeok Lee;Sunmog Yeo;Jung-Hee Lee;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: Jan 2018, volume: 65, issue:1, pages: 579 - 582
Publisher: IEEE
 
» PROVEST: Provenance-Based Trust Model for Delay Tolerant Networks
Abstract:
Delay tolerant networks (DTNs) are often encountered in military network environments where end-to-end connectivity is not guaranteed due to frequent disconnection or delay. This work proposes a provenance-based trust framework, namely PROVEST (PROVEnance-baSed Trust model) that aims to achieve accurate peer-to-peer trust assessment and maximize the delivery of correct messages received by destination nodes while minimizing message delay and communication cost under resource-constrained network environments. Provenance refers to the history of ownership of a valued object or information. We leverage the interdependency between trustworthiness of information source and information itself in PROVEST. PROVEST takes a data-driven approach to reduce resource consumption in the presence of selfish or malicious nodes while estimating a node's trust dynamically in response to changes in the environmental and node conditions. This work adopts a model-based method to evaluate the performance of PROVEST (i.e., trust accuracy and routing performance) using Stochastic Petri Nets. We conduct a comparative performance analysis of PROVEST against existing trust-based and non-trust-based DTN routing protocols to analyze the benefits of PROVEST. We validate PROVEST using a real dataset of DTN mobility traces.
Autors: Jin-Hee Cho;Ing-Ray Chen;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Jan 2018, volume: 15, issue:1, pages: 151 - 165
Publisher: IEEE
 
» Psst, Can You Keep a Secret?
Abstract:
The security of encrypted data depends not only on the theoretical properties of cryptographic primitives but also on the robustness of their implementations in software and hardware. Threshold cryptography introduces a computational paradigm that enables higher assurance for such implementations.
Autors: Apostol Vassilev;Nicky Mouha;Luís Brandão;
Appeared in: Computer
Publication date: Jan 2018, volume: 51, issue:1, pages: 94 - 97
Publisher: IEEE
 
» PtSe2 Field-Effect Transistors: New Opportunities for Electronic Devices
Abstract:
PtSe2, a new family of transition metal dichalcogenides, has been explored for electronic device applications using density functional theory and non-equilibrium Green’s function within the third nearest neighbor tight-binding approximation. Interestingly, despite its small effective mass ( as low as ; being electron rest mass), PtSe2 has large density of states due to its unique six-valley conduction band within the first Brillouin zone, unlike MoX2 family. This has direct impacts on the device characteristics of PtSe2 field-effect transistors, resulting in superior on-state performance (30% higher on current and transconductance) as compared with the MoSe2 counterpart. Our simulation shows that the PtSe2 device with a channel longer than 15 nm exhibits near-ideal subthreshold swing, and sub-100 mV/V of drain-induced barrier lowering can be achieved with an aggressively scaled gate oxide, demonstrating new opportunities for electronic devices with novel PtSe2.
Autors: AbdulAziz AlMutairi;Demin Yin;Youngki Yoon;
Appeared in: IEEE Electron Device Letters
Publication date: Jan 2018, volume: 39, issue:1, pages: 151 - 154
Publisher: IEEE
 
» Pulse Parabolic Equation Method for Loran-C ASF Prediction Over Irregular Terrain
Abstract:
We previously introduced an efficient parabolic equation (PE) method to solve the Loran-C additional secondary factors (ASFs) in the presence of irregular terrain. However, traditional PE analysis, based on the approximation of a narrowband Loran-C source to a 100 kHz sinusoidal source, is not sufficient for realistic Loran-C ASF prediction. In this letter, a pulse PE method is employed to further improve the accuracy of the Loran-C ASF prediction over irregular terrain. The main idea of this approach is that it converts the time-domain wave propagation problems to the frequency-domain wave propagation ones, which can be solved by the traditional PE solution. Numerical examples illustrate the accuracy and effectiveness of the proposed method.
Autors: Dan-Dan Wang;Xiao-Li Xi;Li-Li Zhou;Yu-Rong Pu;Jin-Sheng Zhang;
Appeared in: IEEE Antennas and Wireless Propagation Letters
Publication date: Jan 2018, volume: 17, issue:1, pages: 168 - 171
Publisher: IEEE
 
» Pulsed Vertical Dipole Response of a Thin Sheet With High-Contrast Dielectric and Conductive Properties
Abstract:
The 3-D time-domain Green’s function (GF) for the vector potential excited by a transient vertical electric dipole in the presence of a thin sheet with high-contrast dielectric and conductive properties is derived using a modified Cagniard–de Hoop approach. The resulting expression involves the numerical evaluation of a 2-D integral over a finite integration domain, computationally much less expensive than the direct numerical evaluation of the inverse Laplace/Hankel transform of the relevant spectral-domain GF. Expressions for the transient electromagnetic fields can thus be obtained, and numerical results are provided, which illustrate their salient features and validate the proposed formulation.
Autors: Paolo Burghignoli;Giampiero Lovat;Rodolfo Araneo;Salvatore Celozzi;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2018, volume: 66, issue:1, pages: 217 - 225
Publisher: IEEE
 
» QoS-Aware Energy-Efficient Association and Resource Scheduling for HetNets
Abstract:
A heterogeneous network (HetNet) can actively utilize the spectrum reuse with low power consumption, and thus is promising for the next-generation cellular networks. However, there are some technical challenges to be overcome in order for HetNets to be practical, and we address the following two in this paper. One is how to formulate the association and resource scheduling problem in a way that an optimal solution can be found in a reasonable amount of time, and the other is how to accommodate varying users’ demand. In order to minimize the power consumption and to satisfy varying users’ quality of service requirements, we propose a low-complex, distributed association and resource allocation scheme. By taking a cost-based approach, we first separate a nonconvex joint association and resource allocation problem into two subproblems. The channel allocation and base station assignment problem is then relaxed so that the problem becomes tractable. For the power allocation problem, we introduce a low-complex iterative algorithm by using the decomposition theory. The evaluation results show that the proposed solution can maintain the overall power consumption minimized while satisfying the QoS requirements.
Autors: Taewoon Kim;J. Morris Chang;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2018, volume: 67, issue:1, pages: 650 - 664
Publisher: IEEE
 
» QoS-Aware Power Management in LTE-A Networks Under Heterogeneous Traffics
Abstract:
In 3GPP LTE-A releases v.8 and beyond, the plug and play nature of the eNodeBs lets a dense deployment of eNodeBs, thus, causing over-provisioned network infrastructure. Here, while most of the recent studies aim to optimize power consumption on a single traffic type, we provide a novel framework that corresponds both power adjustment and quality of users (QoS) requirements of end-users with multitraffic types. In this manner, we propose a novel energy efficiency coefficient (EEC) considering QoS and channel utilization while reducing power consumption. Moreover, our proposed resource auction module assigns resource blocks to low-utilized cellular networks. Furthermore, the traffic types are modeled with a queuing theoretic approach. We also define an optimization problem that employs novel EEC parameters to determine new power levels (8-levels) for eNodeBs’ configurations with less power consumption. To solve this optimization problem, we introduce a novel heuristic called “Multi Level Branch and Bound Algorithm” (MLBB). MLBB algorithm contains two nested branch and bound algorithms that manipulates end-users differently. Consequently, our proposed methodology serves end-users with 67% better QoS than the conventional mechanisms.
Autors: Müge Erel Özçevik;Gökhan Seçinti;Berk Canberk;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2018, volume: 67, issue:1, pages: 674 - 688
Publisher: IEEE
 
» qSwitch: Dynamical Off-Chip Bandwidth Allocation Between Local and Remote Accesses
Abstract:
Multisocket computer systems are popular in workstations and servers. However, they suffer from the relatively low bandwidth of intersocket communication especially for massive parallel workloads that generate many intersocket requests for synchronizations and remote memory accesses. Intersocket traffic puts pressure on the underlying network connecting all processors with a limited bandwidth confined by pin resources. Given this constraint, we propose to dynamically increase the intersocket bandwidth by sacrificing off-chip memory bandwidth when systems have heavy intersocket communication but few off-chip memory accesses. Our design increases the physical bandwidth for intersocket communication via switching the function of pins from off-chip memory accesses to intersocket communication and can achieve an average performance speedup of 1.28 in geocentric mean for selected parallel multithreaded benchmarks.
Autors: Shaoming Chen;Lu Peng;Samuel Irving;Zhou Zhao;Weihua Zhang;Ashok Srivastava;
Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Publication date: Jan 2018, volume: 37, issue:1, pages: 75 - 87
Publisher: IEEE
 
» Quality of Experience in a Stereoscopic Multiview Environment
Abstract:
In this paper, we investigate how visualization factors, such as disparity, mobility, angular resolution, and viewpoint interpolation, influence the quality of experience (QoE) in a stereoscopic multiview environment. In order to do so, we set up a dedicated testing room and conducted subjective experiments. We also developed a framework that emulates a supermultiview environment. This framework can be used to investigate and assess the effects of angular resolution and viewpoint interpolation on the QoE produced by multiview systems, and provide relevant cues as to how the baselines of cameras and interpolation strategies in such systems affect user experience. Aspects such as visual comfort, model fluidity, sense of immersion, and the three-dimensional (3D) experience as a whole have been assessed for several test cases. Obtained results suggest that user experience in an motion parallax environment is not as critically influenced by configuration parameters such as disparity as initially thought. In addition, extensive subjective tests have indicated that while users are very sensitive to angular resolution in multiview 3D systems, this sensitivity tends not to be as critical when a user is performing a task that involves a great amount of interaction with the multiview content. These tests have also indicated that interpolating intermediate viewpoints can be effective in reducing the required view density without degrading the perceived QoE.
Autors: Felipe M. L. Ribeiro;José F. L. de Oliveira;Alexandre G. Ciancio;Eduardo A. B. da Silva;Cássius R. D. Estrada;Luiz G. C. Tavares;Jonathan N. Gois;Amir Said;Marcela C. Martelotte;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jan 2018, volume: 20, issue:1, pages: 1 - 14
Publisher: IEEE
 
» Quality-Balanced User Clustering Schemes for Non-Orthogonal Multiple Access Systems
Abstract:
Non-orthogonal multiple access (NOMA) is a promising technology aimed at improving the bandwidth efficiency of wireless transmissions. In this letter, we focus on the optimization of user clustering and power allocation for an NOMA system under a service rate constraint, where the goal is to maximize the total sum rate. Based on the optimal power allocation in a cluster, we propose a suboptimal solution—the quality-balanced clustering approach to optimize the total sum rate in a system. According to the simulations, the proposed user clustering and power allocation schemes can achieve the maximum total sum rate obtained via exhaustive search optimization. The proposed schemes have very low computational complexity, and thus are suitable for real-time NOMA transmissions.
Autors: Yuh-Ren Tsai;Hsuan-An Wei;
Appeared in: IEEE Communications Letters
Publication date: Jan 2018, volume: 22, issue:1, pages: 113 - 116
Publisher: IEEE
 
» Quantized Feedback-Based Diagonal Precoding for $N times 1$ MISO System With Generalized Orthogonal Space-Time Block Codes
Abstract:
In this paper, we propose an imperfect quantized feedback-based diagonal precoding scheme for generalized orthogonal space-time block codes in an multiple-input single-output (MISO) wireless communication system employing -QAM constellation. It is well known that a feedback-based precoding scheme aids channel adaptive signaling in wireless communication system and capitulates large improvements in almost all performance metrics. However, a practical feedback link is susceptible to error due to wireless channel fading and leads to wrong precoder selection. Therefore, a signal-to-noise ratio (SNR) adaptive error-tolerant weighting scheme is introduced which provides significant gain in comparison with another proposed arbitrarily fixed SNR error-tolerant weighting scheme. At first, a tight approximate closed-form expression of average symbol-error-rate (SER) and an exact analytical expression of outage probability are derived under imperfect feedback information with the help of order statistics. By minimizing the derived average SER, optimized transmit weights for the diagonal precoding matrix (based on feedback bits) are obtained. Later, a closed-form expression of the ergodic capacity with erroneous feedback bits for arbitrary MISO system is also provided by using the moment generating function approach. Further, numerical results show that the considered error-tolerant schemes outperform the uniform power allocation scheme in term of all the investigated performance metrics.
Autors: Ankit Garg;Manav R. Bhatnagar;Olivier Berder;Baptiste Vrigneau;
Appeared in: IEEE Transactions on Communications
Publication date: Jan 2018, volume: 66, issue:1, pages: 91 - 104
Publisher: IEEE
 
» Queueing Stability and CSI Probing of a TDD Wireless Network With Interference Alignment
Abstract:
This paper characterizes the performance in terms of queueing stability of a network composed of multiple MIMO transmitter-receiver pairs taking into account the dynamic traffic pattern and the probing/feedback cost. We adopt a centralized scheduling scheme that selects a number of active pairs in each time-slot. We consider that the transmitters apply interference alignment (IA) technique if two or more pairs are active, whereas in the special case where one pair is active point-to-point MIMO singular value decomposition (SVD) is used. We consider a time-division duplex (TDD) system where transmitters acquire their channel state information (CSI) by decoding the pilot sequences sent by the receivers. Since global CSI knowledge is required for IA, the transmitters have also to exchange their estimated CSIs over a backhaul of limited capacity (i.e. imperfect case). Under this setting, we characterize in this paper the stability region of the system under both the imperfect and perfect (i.e. unlimited backhaul) cases, then we examine the gap between these two resulting regions. Further, under each case we provide a centralized probing policy that achieves the max stability region. These stability regions and scheduling policies are given for the symmetric system, where all the path loss coefficients are equal to each other, as well as for the general system. For the symmetric system, we provide the conditions under which IA yields a queueing stability gain compared to SVD. Under the general system, the adopted scheduling policy is of a high computational complexity for moderate numbers of pairs, consequently we propose an approximate policy that has a reduced complexity but that achieves only a fraction of the system stability region. A characterization of this fraction is provided.
Autors: Matha Deghel;Mohamad Assaad;Mérouane Debbah;Anthony Ephremides;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jan 2018, volume: 64, issue:1, pages: 547 - 576
Publisher: IEEE
 
» R-FFAST: A Robust Sub-Linear Time Algorithm for Computing a Sparse DFT
Abstract:
The fast Fourier transform is the most efficiently known way to compute the discrete Fourier transform (DFT) of an arbitrary -length signal, and has a computational complexity of . If the DFT of the signal has only non-zero coefficients (where ), can we do better? We addressed this question and presented a novel fast Fourier aliasing-based sparse transform (FFAST) algorithm that cleverly induces sparse-graph alias codes in the DFT domain, via a Chinese-remainder-theorem-guided sub-sampling operation in the time-domain. The induced sparse-graph alias codes are then exploited to devise a fast and iterative onion-peeling style decoder that computes -sparse DFT of an -length signal using only time-domain samples and computations. In this paper, we generalize the FFAST framework by Pawar and Ramchandran to the noisy setting where the time-domain samples are corrupted by white Gaussian noise. We show that the noise-robust R-FFAST algorithm computes a -sparse DFT of an -length signal using noise-corrupted time-domain samples in complexity, i.e., sub-linear sample and time complexity. In Section IX, we provide extensive simulation results validating the empirical performance of the R-FFAST algorithm, e.g., we show that the R-FFAST algorithm computes a 50-sparse DFT of an ≈ 10 million length signal using only 4800 noisy samples with an effective signal-to-noise ratio of 5 dB. We also provide comparison of the run-time performance of several existing sparse Fourier transform implementations with that of the R-FFAST and show that it is almost 20 times faster, for comparable settings, than the state-of-the-art algorithm, while simultaneously providing better support recovery guarantees. While our theoretical results are for signals with a uniformly random support of the non-zero DFT coefficients and additive white Gaussian noise, we provide simulation results, which demonstrate that the R-FFAST algorithm performs well even for signals like magnetic resonance images, that have an approximately sparse Fourier spectrum with a non-uniform support for the dominant DFT coefficients.
Autors: Sameer Pawar;Kannan Ramchandran;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jan 2018, volume: 64, issue:1, pages: 451 - 466
Publisher: IEEE
 
» Radar Image-Based Positioning for USV Under GPS Denial Environment
Abstract:
Unmanned surface vehicle (USV) is an important application of unmanned systems, and these USVs provide safe and secure operation in hostile environments. But these USVs are highly reliant on their positioning system, such as global position system (GPS), and loss of positioning information from GPS can cause catastrophe. To overcome this positioning challenge for a USV under a GPS denial environment, we propose a real-time positioning algorithm based on radar and satellite images to determine the USV position. The algorithm takes coastline as a registration feature to implement an image registration between a horizontal viewing angle image from a radar and a vertical viewing angle image from a satellite. The contributions of this paper consist of two parts. First, a coastline feature extraction method based on edge gray features for both radar and satellite images is provided. Second, a high-efficiency image registration method, which takes the dimensionality reduction distance as an indicator, was proposed for the USV embedded system. The results from six typical application scenarios show that the maximum positioning error of the proposed algorithm is 28.02 m under the worst case. A continuous positioning experiment shows that the average error of the algorithm is 9.77 m, which indicates that the algorithm can meet the positioning requirements of a USV under GPS denial environment.
Autors: Hongjie Ma;Edward Smart;Adeel Ahmed;David Brown;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Jan 2018, volume: 19, issue:1, pages: 72 - 80
Publisher: IEEE
 
» Radial Velocity Retrieval for Multichannel SAR Moving Targets With Time–Space Doppler Deambiguity
Abstract:
In this paper, with respect to multichannel synthetic aperture radar (SAR), we first formulate the problems of Doppler ambiguities on the radial velocity (RV) estimation of a ground moving target in the range-compressed domain, the range-Doppler domain, and the image domain, respectively. It is revealed that in these problems, the cascaded time–space Doppler ambiguity (CTSDA) may arise; that is, the time domain Doppler ambiguity in each channel arises first and then the spatial domain Doppler ambiguity among multichannels arises second. Accordingly, the multichannel SAR systems with different parameters are investigated in three cases with different Doppler ambiguity properties. Then, a multifrequency SAR is proposed for the RV estimation by solving the ambiguity problem based on the Chinese remainder theorem (CRT). In the first two cases, the ambiguity problem can be solved by the existing closed-form robust CRT. In the third case, it is found that the problem is different from the conventional CRT problem and we call it a double remaindering problem in this paper. We then propose a sufficient condition under which the double remaindering problem, i.e., the CTSDA, can also be solved by the closed-form robust CRT. When the sufficient condition is not satisfied, a searching-based method is proposed. Finally, some results of numerical experiments are provided to demonstrate the effectiveness of the proposed methods.
Autors: Jia Xu;Zu-Zhen Huang;Zhi-Rui Wang;Li Xiao;Xiang-Gen Xia;Teng Long;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jan 2018, volume: 56, issue:1, pages: 35 - 48
Publisher: IEEE
 
» Radiation of a Charge Intersecting a Boundary Between a Bilayer Area and a Homogeneous One in a Circular Waveguide
Abstract:
This paper is devoted to the analysis of electromagnetic field excited by a charge moving in a circular waveguide, which consists of two semi-infinite parts. The charge moves with a constant velocity along the waveguide axis from the partially dielectric section into the homogeneous one. It is assumed that Cherenkov radiation is generated in the bilayer section. The total field is represented as a sum of a known forced field that is the field of the charge in the infinite regular waveguide and a free field resulting from the presence of the transverse boundary. The infinite system of algebraic equations for amplitudes of the free-field modes is derived. The further analysis is conducted using numerical calculations. Special attention is given to the study of the so-called Cherenkov-transition radiation (CTR) within the homogeneous part of the waveguide volume. Typical distributions of CTR over frequencies and modes are presented for the case when the channel and the homogeneous area are free of medium. Analytical results obtained for the point charge are generalized for the charged bunch with an arbitrary profile and verified using direct simulations for the case of Gaussian bunch.
Autors: Aleksandra A. Grigoreva;Andrey V. Tyukhtin;Viktor V. Vorobev;Sergey Antipov;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jan 2018, volume: 66, issue:1, pages: 49 - 55
Publisher: IEEE
 
» Radio Frequency Interference Suppression Algorithm in Spatial Domain for Compact High-Frequency Radar
Abstract:
High-frequency (HF) ground wave radar is an important tool for sea state measurement and low-altitude target detection. Dense radio frequency interference (RFI) in the HF band inhibits the extraction of sea state parameters and degrades the performance of radar. Though many interference suppression methods based on large arrays have been proposed, most of them are weak to deal with the interference in small-aperture radar. In this letter, a spatial subspace method is proposed to suppress RFI, which uses two crossed-loop/monopole antennas to construct interference subspace at the reserved range bins and projects the echoes onto its orthogonal subspace at the interested range bins. The processed results of measured data from OSMAR-SD verify the high performance of this algorithm for dense RFI suppression. Apart from that, the data utilization ratio and the accuracy of estimating wave height are both improved significantly after the RFI suppression.
Autors: Zhen Tian;Biyang Wen;Lijie Jin;Yingwei Tian;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jan 2018, volume: 15, issue:1, pages: 102 - 106
Publisher: IEEE
 
» Radio Map Interpolation Using Graph Signal Processing
Abstract:
Interpolating a radio map is a problem of great relevance in many scenarios such as network planning, network optimization, and localization. In this letter, such a problem is tackled by leveraging recent results from the emerging field of signal processing on graphs. A technique for interpolating graph structured data is adapted to the problem at hand by using different graph creation strategies, including ones that explicitly consider NLOS propagation conditions. Extensive experiments in a realistic large-scale urban scenario demonstrate that the proposed technique outperforms other traditional methods, such as IDW, RBF, and model-based interpolation.
Autors: Alessandro Enrico Cesare Redondi;
Appeared in: IEEE Communications Letters
Publication date: Jan 2018, volume: 22, issue:1, pages: 153 - 156
Publisher: IEEE
 
» Random Forest Ensembles and Extended Multiextinction Profiles for Hyperspectral Image Classification
Abstract:
Classification techniques for hyperspectral images based on random forest (RF) ensembles and extended multiextinction profiles (EMEPs) are proposed as a means of improving performance. To this end, five strategies—bagging, boosting, random subspace, rotation-based, and boosted rotation-based—are used to construct the RF ensembles. EPs, which are based on an extrema-oriented connected filtering technique, are applied to the images associated with the first informative components extracted by independent component analysis, leading to a set of EMEPs. The effectiveness of the proposed method is investigated on two benchmark hyperspectral images: the University of Pavia and Indian Pines. Comparative experimental evaluations reveal the superior performance of the proposed methods, especially those employing rotation-based and boosted rotation-based approaches. An additional advantage is that the CPU processing time is acceptable.
Autors: Junshi Xia;Pedram Ghamisi;Naoto Yokoya;Akira Iwasaki;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jan 2018, volume: 56, issue:1, pages: 202 - 216
Publisher: IEEE
 

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  2015:   January     February     March     April     May     June     July     August     September     October     November     December    

  2014:   January     February     March     April     May     June     July     August     September     October     November     December    

  2013:   January     February     March     April     May     June     July     August     September     October     November     December    

  2012:   January     February     March     April     May     June     July     August     September     October     November     December    

  2011:   January     February     March     April     May     June     July     August     September     October     November     December    

  2010:   January     February     March     April     May     June     July     August     September     October     November     December    

  2009:   January     February     March     April     May     June     July     August     September     October     November     December    

 
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