Electrical and Electronics Engineering publications abstract of: 03-2017 sorted by title, page: 1

» A Hand-Held Assistant for Semiautomated Percutaneous Needle Steering
Abstract:
Objective: Permanent prostate brachytherapy is an effective and popular treatment modality for prostate cancer in which long needles are inserted into the prostate. Challenges associated with manual needle insertion such as needle deflection limit this procedure to primarily treat the entire prostate gland even for patients with localized cancer. In this paper, we present a new semiautomated hand-held needle steering assistant designed to help surgeons improve needle placement accuracy. Methods: Regular clinical brachytherapy needles are connected to a compact device that the surgeon holds. As the surgeon inserts the needle, the device rotates the needle base on a measured and calculated basis in order to produce a desired trajectory of the needle tip. A novel needle–tissue interaction model and a steering algorithm calculate such control actions based on ultrasound images of the needle in tissue. The assistant can also apply controlled longitudinal microvibrations to the needle that reduce needle–tissue friction. Results: Experimental validation of the proposed system in phantom and ex-vivo biological tissue report an average needle targeting accuracy of 0.33 mm over 72 needle insertions in 12 different experimental scenarios. Conclusion: We introduce a new framework for needle steering in prostate brachytherapy in which the surgeon remains in charge of the needle insertion. The device weighs 160 g, making it easy to incorporate with current insertion techniques. Significance: Expected benefits of the proposed system include more precise needle targeting accuracy, which can result in improved focal treatment of prostate cancer.
Autors: Carlos Rossa;Nawaid Usmani;Ronald Sloboda;Mahdi Tavakoli;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Mar 2017, volume: 64, issue:3, pages: 637 - 648
Publisher: IEEE
 
» A Hidden Markov Model for 3D Catheter Tip Tracking With 2D X-ray Catheterization Sequence and 3D Rotational Angiography
Abstract:
In minimal invasive image guided catheterization procedures, physicians require information of the catheter position with respect to the patient’s vasculature. However, in fluoroscopic images, visualization of the vasculature requires toxic contrast agent. Static vasculature roadmapping, which can reduce the usage of iodine contrast, is hampered by the breathing motion in abdominal catheterization. In this paper, we propose a method to track the catheter tip inside the patient’s 3D vessel tree using intra-operative single-plane 2D X-ray image sequences and a peri-operative 3D rotational angiography (3DRA). The method is based on a hidden Markov model (HMM) where states of the model are the possible positions of the catheter tip inside the 3D vessel tree. The transitions from state to state model the probabilities for the catheter tip to move from one position to another. The HMM is updated following the observation scores, based on the registration between the 2D catheter centerline extracted from the 2D X-ray image, and the 2D projection of 3D vessel tree centerline extracted from the 3DRA. The method is extensively evaluated on simulated and clinical datasets acquired during liver abdominal catheterization. The evaluations show a median 3D tip tracking error of 2.3 mm with optimal settings in simulated data. The registered vessels close to the tip have a median distance error of 4.7 mm with angiographic data and optimal settings. Such accuracy is sufficient to help the physicians with an up-to-date roadmapping. The method tracks in real-time the catheter tip and enables roadmapping during catheterization procedures.
Autors: Pierre Ambrosini;Ihor Smal;Daniel Ruijters;Wiro J. Niessen;Adriaan Moelker;Theo Van Walsum;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Mar 2017, volume: 36, issue:3, pages: 757 - 768
Publisher: IEEE
 
» A High Dynamic-Range Neural Recording Chopper Amplifier for Simultaneous Neural Recording and Stimulation
Abstract:
Closed-loop neuromodulation is essential for the advance of neuroscience and for administering therapy in patients suffering from drug-resistant neurological conditions. Neural stimulation generates large artifacts at the recording sites, which easily saturate traditional recording front ends. This paper presents a neural recording chopper amplifier capable of handling in-band artifacts up to 40 mVpp while preserving the accompanying small neural signals. New techniques have been proposed that solve the issues of low input impedance and electrode-offset rejection, which enable a DC input impedance of 300 and a dynamic range of 69 dB (200 Hz–5 kHz) and 78 dB (1–200 Hz). Implemented in a 40-nm CMOS process, the prototype occupies an area of 0.071 mm2/channel, and consumes from a 1.2 V supply. The input-referred noise is (200 Hz–20 kHz) and (1–200 Hz). The total harmonic distortion for a 20-mVp input at 1 kHz is −74 dB. This paper improves the linearity by 14–26 dB, dynamic range by 11–28 dB, and input-impedance for chopped front ends by a factor of 11 as compared with the current state of the art, while achieving similar power and noise performance.
Autors: Hariprasad Chandrakumar;Dejan Marković;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Mar 2017, volume: 52, issue:3, pages: 645 - 656
Publisher: IEEE
 
» A High-Accuracy Wind Power Forecasting Model
Abstract:
In this letter, a forecasting model consisting of the Gaussian process with a novel composite covariance function for high-accuracy wind power forecasting is presented. The proposed composite covariance function is based on the exploration of joint effects between numerical weather prediction features. The performance of the proposed forecasting model is evaluated using the 2012 global energy forecasting competition wind power forecasting data, and the proposed model outperforms all of the competitors.
Autors: Shengchen Fang;Hsiao-Dong Chiang;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1589 - 1590
Publisher: IEEE
 
» A High-Speed and Power-Efficient Voltage Level Shifter for Dual-Supply Applications
Abstract:
This brief presents a fast and power-efficient voltage level-shifting circuit capable of converting extremely low levels of input voltages into high output voltage levels. The efficiency of the proposed circuit is due to the fact that not only the strength of the pull-up device is significantly reduced when the pull-down device is pulling down the output node, but the strength of the pull-down device is also increased using a low-power auxiliary circuit. Postlayout simulation results of the proposed circuit in a 0.18- technology demonstrate a total energy per transition of 157 fJ, a static power dissipation of 0.3 nW, and a propagation delay of 30 ns for input frequency of 1 MHz, low supply voltage level of V, and high supply voltage level of V.
Autors: Seyed Rasool Hosseini;Mehdi Saberi;Reza Lotfi;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Mar 2017, volume: 25, issue:3, pages: 1154 - 1158
Publisher: IEEE
 
» A History of Baseball and Paper Mills [History]
Abstract:
On Saturday night, 22 October 2016, I witnessed the Chicago Cubs clinch a place in baseball's 2016 World Series after capturing the pennant during the National League Central Division playoffs with the Los Angeles Dodgers. Not since 1945 had this baseball club been able to accomplish this extraordinary feat. It was on 28 May 1957, at a National League baseball owners midseason meeting in Chicago, that the decision was made to move the Brooklyn Dodgers franchise to Los Angeles. Chicago, of course, has always been known as a baseball town, and the young Cubs players, in their early 20s, magically captured the hearts of their devoted fans in winning their place in history once again.
Autors: Barry C. Brusso;
Appeared in: IEEE Industry Applications Magazine
Publication date: Mar 2017, volume: 23, issue:2, pages: 7 - 11
Publisher: IEEE
 
» A Hybrid Magnetoelastic Wireless Sensor for Detection of Food Adulteration
Abstract:
This paper investigates a step by step design procedure of a hybrid passive wireless sensor. The hybrid sensor measures both the electrical (dielectric constant) and the mechanical (viscosity) properties of liquid, providing a two-factor quality control. The hybrid sensor is based on an inductor-capacitor resonant tank coupled with a magnetoelastic strip. The mechanical and the electrical resonances change as a function of viscosity and dielectric constant, respectively. Two different hybrid sensor designs are investigated: 1) a parallel plate capacitor coupled with a separate amorphous ferromagnetic magnetoelastic strip (Metglas) and 2) a capacitor made using two parallel mounted magnetoelastic strips. The sensors are integrated as part of the “smart vial” making it field operable for food quality monitoring and control. Here, detection of adulteration in extra virgin olive oil is achieved by measuring the change in viscosity and dielectric constant for different adulteration levels. The real part of the dielectric constant for different liquid samples is measured in the frequency range of 3–24 MHz. The hybrid sensor is able to detect adulteration levels below 10% in volume. These sensors can be integrated with passive RFIDs for simultaneous measurement of multiple samples in an array format.
Autors: Saranraj Karuppuswami;Amanpreet Kaur;Harikrishnan Arangali;Premjeet Prem Chahal;
Appeared in: IEEE Sensors Journal
Publication date: Mar 2017, volume: 17, issue:6, pages: 1706 - 1714
Publisher: IEEE
 
» A Hybrid Recommendation Model for Learning Object Repositories
Abstract:
Learning Objects (LOs) have emerged as a cornerstone approach for the development and distribution of educational content. These resources are distributed by Learning Object Repositories (LORs), which can make it easier for users to find suitable LOs by using Recommender Systems (Rss). This paper presents a hybrid recommendation model for LORs that combines content-based, demographic and context-aware techniques, along with the use of quality and popularity metrics. This article also describes how the model has been used to implement two RSs for two real LORs: ViSH and Europeana. Each of these RSs was evaluated in terms of accuracy, utility,usability and satisfaction perceived by end users. Besides, an A/B testing was performed in ViSH to compare the recommendations of the RS with random suggestions. The results showed that the RSs had a high user acceptance in terms of utility, usability and satisfaction, and that the RSs significantly exceeded the performance achieved by the random recommendations.
Autors: Aldo Gordillo;Enrique Barra;Juan Quemada;
Appeared in: IEEE Latin America Transactions
Publication date: Mar 2017, volume: 15, issue:3, pages: 462 - 473
Publisher: IEEE
 
» A Hybrid Resonant Pulse-Width Modulation Bridgeless AC–DC Power Factor Correction Converter
Abstract:
A hybrid resonant pulse-width modulation (PWM) bridgeless ac–dc power factor correction (PFC) boost converter is proposed for application in power supplies and battery chargers. The bridgeless operation of the proposed converter eliminates the need for the front-end diode bridge rectifier. The PWM switches share the same gating signal, so the converter does not need extra circuitry to sense the positive or negative ac input line-cycle operation. The resonant tank components are relatively small in size and, unlike a totem-pole PFC converter, the hybrid-resonant mode of operation alleviates the reverse-recovery losses for the body diodes of the PWM switches. The inherent inrush current-limiting capabilities improve the system reliability. Moreover, the converter architecture enables simple implementation of lightning and surge protection systems. To verify the proof of concept, experimental results are presented for a 650-W prototype at 70-kHz switching frequency, universal ac input, and 400-V dc output.
Autors: Muntasir Alam;Wilson Eberle;Deepak S. Gautam;Chris Botting;Nicholas Dohmeier;Fariborz Musavi;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1406 - 1415
Publisher: IEEE
 
» A Hybrid Temporal Reasoning Framework for Fall Monitoring
Abstract:
This paper presents a real-time method for detecting a fall at different phases using a wireless tri-axial accelerometer and reports the classification performance when the sensor is placed on different body parts. The proposed hybrid framework combines a rule-based knowledge representation scheme with a time control mechanism and machine-learning-based activity classification. Real-time temporal reasoning is performed using a standard rule-based inference engine. The framework is validated for fall detection performance, false alarm evaluation, and comparison with a highly cited baseline method. Based on a data set with 14 fall types (280 falls) collected from 16 subjects, the highest accuracy values of 86.54%, 87.31%, and 91.15% are obtained for fall detection at pre-impacts, impacts, and post-impacts, respectively. Without post-impact activity information, the side of the waist and chest are the best sensor positions, followed by the head, front of the waist, wrist, ankle, thigh, and upper arm. With post-impact activity information, the best sensor position is the side of the waist, followed by the head, wrist, front of the waist, thigh, chest, ankle, and upper arm. Most false alarms occur during transitions of lying postures. The proposed method is more robust to a variety of fall and activity types and yields better classification performance and false alarm rates compared with the baseline method. The results provide guidelines for sensor placement when developing a fall monitoring system.
Autors: Natthapon Pannurat;Surapa Thiemjarus;Ekawit Nantajeewarawat;
Appeared in: IEEE Sensors Journal
Publication date: Mar 2017, volume: 17, issue:6, pages: 1749 - 1759
Publisher: IEEE
 
» A Hyperheuristic Methodology to Generate Adaptive Strategies for Games
Abstract:
Hyperheuristics have been successfully applied in solving a variety of computational search problems. In this paper, we investigate a hyperheuristic methodology to generate adaptive strategies for games. Based on a set of low-level heuristics (or strategies), a hyperheuristic game player can generate strategies which adapt to both the behavior of the co-players and the game dynamics. By using a simple heuristic selection mechanism, a number of existing heuristics for specialized games can be integrated into an automated game player. As examples, we develop hyperheuristic game players for three games: iterated prisoner's dilemma, repeated Goofspiel and the competitive traveling salesmen problem. The results demonstrate that a hyperheuristic game player outperforms the low-level heuristics, when used individually in game playing and it can generate adaptive strategies even if the low-level heuristics are deterministic. This methodology provides an efficient way to develop new strategies for games based on existing strategies.
Autors: Jiawei Li;Graham Kendall;
Appeared in: IEEE Transactions on Computational Intelligence and AI in Games
Publication date: Mar 2017, volume: 9, issue:1, pages: 1 - 10
Publisher: IEEE
 
» A Linear Equivalent Circuit Model for Depletion-Type Silicon Microring Modulators
Abstract:
We present a linear equivalent circuit model for the depletion-type Si microring modulator (MRM). Our model consists of three blocks: one for parasitic components due to interconnects and pads, one for the electrical elements of the core p-n junction, and the third for a lossy LC tank representing Si MRM optical modulation characteristics. Model parameter values are extracted from measurement of a fabricated Si MRM device. Simulated modulation characteristics with our equivalent circuit show very good agreement with measured results. Using our model, we can analyze Si MRM modulation frequency response characteristics and perform gain-bandwidth product optimization of the entire Si photonic transmitter composed of a Si MRM and electrical driver circuits.
Autors: Myungjin Shin;Yoojin Ban;Byung-Min Yu;Min-Hyeong Kim;Jinsoo Rhim;Lars Zimmermann;Woo-Young Choi;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1140 - 1145
Publisher: IEEE
 
» A Linearizing Digitizer for Wheatstone Bridge Based Signal Conditioning of Resistive Sensors
Abstract:
Output of a typical Wheatstone bridge, when it is connected to measure from a single or a dual resistive element, possesses non-linear characteristic. This paper presents a novel signal conditioning scheme, which provides a linear-digital output directly from the resistive sensor(s) that are connected in such bridge configurations. In the present scheme, the input stage of a dual-slope analog-to-digital converter (DSADC) is suitably augmented to incorporate the quarter-bridge and (or) half-bridge containing the resistive sensor as an integral part of the DSADC. A combination of the current mode excitation and wisely selected integration and de-integration operations of the DSADC enable to achieve linearization in the digitization process itself, leading to an overall reduction in the complexity level and number of blocks used keeping the high accuracy unaltered. A detailed analysis has been conducted to quantify the effect of various sources of errors in the output of the DSADC. The details are presented in the paper. The proposed method not only provides a linear digital output but also drastically reduces the effect on the output due to the lead wires that connect the Wheatstone bridge and the DSADC. Thus, the proposed scheme is well suited for the situations where the sensor(s) is (are) remotely located at a distance. Simulation studies as well as results from a prototype developed and tested establish the practicality of the proposed scheme. The inherent non-linearity of the Wheatstone bridge is reduced by nearly two orders of magnitude.
Autors: Ponnalagu Ramanathan Nagarajan;Boby George;Varadarajan Jagadeesh Kumar;
Appeared in: IEEE Sensors Journal
Publication date: Mar 2017, volume: 17, issue:6, pages: 1696 - 1705
Publisher: IEEE
 
» A Location-Based Mobile Crowdsensing Framework Supporting a Massive Ad Hoc Social Network Environment
Abstract:
This article addresses one of the key challenges of engaging a massive ad hoc crowd by providing sustainable incentives. The incentive model is based on a context-aware cyber-physical spatio-temporal serious game with the help of a mobile crowd sensing mechanism. To this end, this article describes a framework that can create an ad hoc social network of millions of people and provide context-aware serious-game services as an incentive. While interacting with different services, the massive crowd shares a rich trail of geo-tagged multimedia data, which acts as a crowdsourcing eco-system. The incentive model has been tested on the mass crowd at the Hajj since 2014. From our observations, we conclude that the framework provides a sustainable incentive mechanism that can solve many real-life problems such as reaching a person in a crowd within the shortest possible time, isolating significant events, finding lost individuals, handling emergency situations, helping pilgrims to perform ritual events based on location and time, and sharing geo-tagged multimedia resources among a community of interest within the crowd. The framework allows an ad hoc social network to be formed within a very large crowd, a community of interests to be created for each person, and information to be shared with the right community of interests. We present the communication paradigm of the framework, the serious game incentive model, and cloud-based massive geo-tagged social network architecture.
Autors: Md. Abdur Rahman;M. Shamim Hossain;
Appeared in: IEEE Communications Magazine
Publication date: Mar 2017, volume: 55, issue:3, pages: 76 - 85
Publisher: IEEE
 
» A Long Duration Transient Resilient Pipeline Scheme
Abstract:
Single event transients (SETs) in combinational logic remain an important topic in the reliability domain. SETs were traditionally relatively short in comparison to the clock period. The majority of the countermeasures utilizes this property. However, advances in technology scaling will reverse the ratio for complementary metal-oxide semiconductor devices. Investigations show that SETs may last up to multiple clock cycles in the future. So-called long duration transients (LDTs) corrupt almost all available countermeasures. This paper presents a new methodology to tackle LDTs. Dual modular redundancy (DMR) is used to detect any corruption of the application logic. A new micro-rollback scheme expands the DMR architecture with fault correction capabilities. The concept is also capable of handling single event upsets and timing violations. The correction penalty is two clock cycles. The approach was implemented and verified in a Viterbi decoder architecture. The scheme utilizes a newly designed History Cell. The History Cell introduces an area overhead of 97% and a power overhead of 110%, compared to a standard cell DFF.
Autors: Erol Koser;Walter Stechele;
Appeared in: IEEE Transactions on Device and Materials Reliability
Publication date: Mar 2017, volume: 17, issue:1, pages: 12 - 19
Publisher: IEEE
 
» A Low Voltage SRAM Using Resonant Supply Boosting
Abstract:
This paper presents a novel resonating inductor-based supply boosting scheme for low-voltage static random-access memories and logic in deep 14-nm silicon on insulator (SOI) FinFET technologies. The technique combines capacitive (C) and inductive (L) boosting for the first time. Simulation and measured hardware results from a 14-nm test chip show that this new technique is able to improve (down to 0.3 V), functional yield, and access time, when compared with designs with or without capacitive-boosted supplies. Simulations also reveal the optimal combinations of “L” and “C” needed for each to achieve minimal boost voltage, where the static random-access memory can be rendered fully functional in the absence of any assist circuitry. Furthermore, the resonant supply provides power savings compared with a boosted supply alone.
Autors: Rajiv V. Joshi;Matthew M. Ziegler;Holger Wetter;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Mar 2017, volume: 52, issue:3, pages: 634 - 644
Publisher: IEEE
 
» A Low-Power Wireless Piezoelectric Sensor-Based Respiration Monitoring System Realized in CMOS Process
Abstract:
This paper presents a methodology of monitoring respiration pattern using piezoelectric transducer incorporating CMOS integrated circuits for signal processing and data transmission. As a proof of concept, the system has been tested by placing electrodes on human chest using adhesive hydrogel to detect the pulsatile vibration due to respiration. The system can be used either as a wearable device itself or alternatively can be attached to a jacket or a chest belt. The front-end transducer is a piezoelectric material-based sensor, which is comprised of a ferroelectric polymer named polyvinylidene-fluoride (PVDF). PVDF is also biocompatible, which makes the sensor suitable to be used as a wearable device. The charge produced by the sensor is converted to a proportional voltage signal with the help of a charge amplifier designed in a standard 130-nm CMOS process with eight metal and one poly layer. The analog voltage signal acquired from the charge amplifier is then converted into a digital signal using a reconfigurable pipelined analog-to-digital converter for ease of transmission. An impulse-radio ultra-wideband transmitter operating in the frequency range of 3.1–5 GHz is designed for wireless transmission of the data. The smaller footprint, lighter weight, wireless telemetry, and low-cost material along with the low-power integrated CMOS circuitry for signal processing and data transmission make the proposed system an attractive choice for stable respiration monitoring system.
Autors: Ifana Mahbub;Salvatore Andrea Pullano;Hanfeng Wang;Syed Kamrul Islam;Antonino S. Fiorillo;Gary To;M. R. Mahfouz;
Appeared in: IEEE Sensors Journal
Publication date: Mar 2017, volume: 17, issue:6, pages: 1858 - 1864
Publisher: IEEE
 
» A Low-Profile Aperture-Coupled Microstrip Antenna With Enhanced Bandwidth Under Dual Resonance
Abstract:
A low-profile aperture-coupled microstrip patch antenna (MPA) using the TM10 and TM30 resonant modes to enhance the impedance bandwidth is proposed in this paper. Based on the cavity model for a square MPA, the TM10 and TM30 modes as well as both higher odd-order and even-order modes between them can be characterized. In order to combine the dual radiative resonant modes for a wide impedance bandwidth, a rectangular radiating patch with an aperture-coupled feeder is employed and theoretically investigated at first, aiming to demonstrate that all of the undesired modes between them can be removed effectively. After that, by loading the shorting pins properly underneath the patch, the resonant frequency of TM10 mode is shown to progressively turn up with slight effect on that of TM30 mode. As a result, these two radiative modes can be allocated in proximity to each other, resulting in a wide impedance bandwidth with a stable radiation pattern and the same far-field polarization. Moreover, the principal parameters of the MPA have been extensively studied in order to investigate the sensitivity in input impedance of the aperture-fed patch antenna. Finally, the proposed antenna is fabricated and measured. Simulated and measured results are found in good agreement with each other and illustrate that the antenna achieves a wide impedance bandwidth of about 15.2% in fraction or 2.32–2.70 GHz under dB, while keeping a low profile property with the height of 0.032 free-space wavelength. Besides, a stable gain varied from 3 to 6.8 dBi within the whole operating band is also obtained.
Autors: Neng-Wu Liu;Lei Zhu;Wai-Wa Choi;Xiao Zhang;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Mar 2017, volume: 65, issue:3, pages: 1055 - 1062
Publisher: IEEE
 
» A Mathematical Model for Determining an Electrohydrodynamic Accelerator’s Monopolar Flow Limit During Positive Corona Discharge
Abstract:
This paper presents a mathematical model establishing the velocity limit of electrohydrodynamics fluid accelerators with tip to plane and cylinder to plane electrode configurations. The model is based on the calculation of the electric field lines length and trajectory, allowing practical use even if only the spatial characteristics of the geometry, the fluid’s ion mobility and the applied voltage are known. Experiments are performed with wire-plane and needle-grid electrode configurations to validate the developed mathematical model, both for the calculation of the average flow limit of the geometry and for the calculation of the flow limit at the end of each electric field line.
Autors: Emmanouil D. Fylladitakis;Antonios X. Moronis;Michael P. Theodoridis;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Mar 2017, volume: 45, issue:3, pages: 432 - 440
Publisher: IEEE
 
» A Meeting of Materials: Integrating Diverse Semiconductor Technologies for Improved Performance at Lower Cost
Abstract:
Semiconductor technology has seen rapid advances in recent years. Complementary?metal-oxide-semiconductor (CMOS) technology is providing tremendous digital processing power by integrating billions of transistors. Indium phosphide (InP) has bridged the terahertz frequency barrier. Gallium nitride (GaN) is offering unprecedented solid-state RF power across the microwave spectrum. Diverse, accessible heterogeneous integration (DAHI) allows engineers to take advantage of all of these advances by combining them along with other semiconductor technologies onto a single chip. DAHI offers the ultimate in RF, mixedsignal, and digital capability for future mobile applications that will demand smaller size and weight with lower power and cost.
Autors: Augusto Gutierrez-Aitken;Bryan Yi-Cheng Wu;Dennis Scott;Ken Sato;Benjamin Poust;Monte Watanabe;Cedric Monier;Nancy Lin;Xiang Zeng;Eric Nakamura;Peter Cheng;Eric Kaneshiro;Wesley Chan;Ioulia Smorchkova;Khanh Thai;Sujane Wang;David Slavin;Aaron Oki;Rey
Appeared in: IEEE Microwave Magazine
Publication date: Mar 2017, volume: 18, issue:2, pages: 60 - 73
Publisher: IEEE
 
» A Method and Toolkit for Digital Musical Instruments: Generating Ideas and Prototypes
Abstract:
Digital musical instruments (DMIs) make up a class of devices in which gestural control and sound production are physically decoupled, but digitally mapped. This work discusses aspects of DMI design by focusing on the complexity of the design space and the importance of prototyping cycles. The authors' research questions cover how to provide an initial path for generating DMI ideas and how to reduce the time and effort required to build functional DMI prototypes. To address these questions, they propose a new methodology and an associated physical prototyping toolkit, which has building blocks inspired by of existing instruments. Preliminary tests with musicians and DMI designers revealed a strong potential for its use in the development of DMIs, and also uncovered limitations of the current toolkit. This article is part of a special issue on multimedia technologies for enriched music.
Autors: Filipe Calegario;Marcelo M. Wanderley;Stéphane Huot;Giordano Cabral;Geber Ramalho;
Appeared in: IEEE Multimedia
Publication date: Mar 2017, volume: 24, issue:1, pages: 63 - 71
Publisher: IEEE
 
» A Method to Start Rotating Induction Motor Based on Speed Sensorless Model-Predictive Control
Abstract:
In some cases, such as restarting after power interruption or starting a motor rotated by external load, the motor may be rotating before being powered by the inverter. For speed-sensorless operation, as both the initial rotational direction and speed is unknown, it would be difficult to achieve smooth and fast resumption of normal operation if the starting scheme is not deliberately designed. In this paper, a method based on adaptive full order observer (AFO) is proposed to address this problem. For AFO without a properly designed feedback gain matrix, the estimated speed cannot converge to the actual speed if initial estimated speed is significantly lower than the actual speed. Through analyzing the transfer function of stator current error, the convergence condition of speed estimation is deduced. A feedback gain matrix and the condition for shifting to normal operation are subsequently proposed to improve restarting performance. The detailed design and implementation of the proposed method combined with finite control set model-predictive flux control is illustrated. Simulation and experimental results validate the effectiveness of the developed schemes.
Autors: Haitao Yang;Yongchang Zhang;Paul D. Walker;Nong Zhang;Bo Xia;
Appeared in: IEEE Transactions on Energy Conversion
Publication date: Mar 2017, volume: 32, issue:1, pages: 359 - 368
Publisher: IEEE
 
» A Methodology for Short-Term Load Forecasting
Abstract:
Demand forecasting is important for electrical analysis development by utilities. It requires low error levels in order to reach reliability in electrical analysis. However, the demand for energy has dissimilar profiles variations depending on the type of day, weather conditions and geographical area. For this reason, it is necessary to group those curves showing similar behaviors and characterize them to establish which factors are significant for understanding. This paper proposes a novel methodology to identify those significant factors in the forecasting model for energy demand, and measure their effect on the Mean Absolute Percentage Error (MAPE) criterion and error performance. The experimental results show advantages of this methodology for zones with several behaviors in hourly power consumption.
Autors: Jamer Jimenez Mares;Katheryn Donado Mercado;Christian G. Quintero M.;
Appeared in: IEEE Latin America Transactions
Publication date: Mar 2017, volume: 15, issue:3, pages: 400 - 407
Publisher: IEEE
 
» A Minorization–Maximization Algorithm for Maximizing the Secrecy Rate of the MIMOME Wiretap Channel
Abstract:
We consider physical layer security in a multi-input multi-output multi-eavesdropper wiretap channel and present an exact solution to the problem of secrecy rate maximization. A system model with multiple multi-antenna eavesdroppers and multiple multi-antenna full-duplex receivers is considered, which is general enough such that models existing in the literature may be considered as special cases. In particular, we perform joint beamforming and artificial noise optimization in an effort to maximize the achievable secrecy rate. The optimization is performed in the presence of artificial noise generated by both transmitter and legitimate receivers. The resulting optimization problem is non-convex and difficult to solve. We develop a minorization–maximization algorithm to solve the problem exactly and the results can therefore be used to benchmark existing methods. Numerical results are presented to demonstrate the efficacy of the proposed approach.
Autors: Mudassir Masood;Ali Ghrayeb;Prabhu Babu;Issa Khalil;Mazen Hasna;
Appeared in: IEEE Communications Letters
Publication date: Mar 2017, volume: 21, issue:3, pages: 520 - 523
Publisher: IEEE
 
» A Mixed Interval Power Flow Analysis Under Rectangular and Polar Coordinate System
Abstract:
A Rectangular Interval Power Flow (RIPF) method is proposed to improve solutions for intervals of power flow problems due to nondeterministic characteristics of demand loads and output of generators. It is based on affine arithmetic which is a self-validated numerical analysis and serves to improve the interval results through optimization method. Since no approximation is presumed, the RIPF method acquires narrower intervals of voltage phase and active power of branches than Polar Interval Power Flow (PIPF), it is an excellent method raised before. However, as RIPF is no better than that of PIPF for estimating intervals of voltage magnitude, because it relaxes restriction of the voltage equations. Therefore, a Mixed Interval Power Flow (MIPF) method is envisaged and developed in the paper to incorporate merits of RIPF for computing the intervals of voltage phase and active power of branches but not giving the advantage of PIPF for evaluating intervals of voltage magnitude. As a validation of our suggested approach, two case studies are carried out, and results conclude that the MIPF method acquires more accurate power flow intervals than the conventional method.
Autors: Cong Zhang;Haoyong Chen;Honwing Ngan;Ping Yang;Dong Hua;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1422 - 1429
Publisher: IEEE
 
» A Model Predictive Control Approach for Low-Complexity Electric Vehicle Charging Scheduling: Optimality and Scalability
Abstract:
With the increasing adoption of plug-in electric vehicles (PEVs), it is critical to develop efficient charging coordination mechanisms that minimize the cost and impact of PEV integration to the power grid. In this paper, we consider the optimal PEV charging scheduling, where the noncausal information about future PEV arrivals is not known in advance, but its statistical information can be estimated. This leads to an “online” charging scheduling problem that is naturally formulated as a finite-horizon dynamic programming with continuous state space and action space. To avoid the prohibitively high complexity of solving such a dynamic programming problem, we provide a model predictive control (MPC)-based algorithm with computational complexity , where is the total number of time stages. We rigorously analyze the performance gap between the near-optimal solution of the MPC-based approach and the optimal solution for any distributions of exogenous random variables. Furthermore, our rigorous analysis shows that when the random process describing the arrival of charging demands is first-order periodic, the complexity of the proposed algorithm can be reduced to , which is independent of . Extensive simulations show that the proposed online algorithm performs very closely to the optimal online algorithm. The performance gap is smaller than in most cases.
Autors: Wanrong Tang;Ying Jun (Angela) Zhang;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1050 - 1063
Publisher: IEEE
 
» A Model to Represent Correlated Time Series in Reliability Evaluation by Non-Sequential Monte Carlo Simulation
Abstract:
This paper proposes a model that represents statistically dependent time-varying quantities, such as loads, wind power generation, and water inflows, and can be applied to evaluate power systems composite reliability by Non-Sequential Monte Carlo Simulation (MCS). This proposal is based on nonparametric stochastic models, which do not require a priori characterizations of the probability density functions of the random variables. Additionally, the maximal information coefficient, which allows mapping nonlinear relationships between the variables, and Bayesian network structures, which allow handling high dimensionality problems when multiple time series are represented, are applied. The proposed model allows reliability indices to be obtained with the same accuracy as the Sequential MCS but with computational costs on the order of the Non-Sequential MCS. The model is flexible enough to represent the relationships between variables with different levels of discretization, as in the case of the wind power generation and water inflows of a hydroelectric system.
Autors: Carmen Lucia Tancredo Borges;Julio A. S. Dias;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1511 - 1519
Publisher: IEEE
 
» A modified analysis of electrical energy consumption in University buildings
Abstract:
To analyze the concept of charge for electricity consumption, it is important to consider the type of billing-rate. Therefore, in this study a change of model analysis for the implementation of the use and consumption of electricity in university buildings is proposed. The approach that is made, is based on recent changes in the cost of energy in relation to the tariff that most university buildings have. Based on the physical conditions, equipment and number of users, in combination with rate type of the university buildings, indicators of consumption and use of electric power are proposed. In the same way, an analysis of the variability of the cost and use of electrical energy that allows identify a change in the actions that traditionally were being made to reduce the costs of billing is made.
Autors: Jesus Martinez Patino;Fernando Ireta Moreno;Miguel Angel Hernandez Figueroa;Jose Merced Lozano Garcia;Heriberto Gutierrez Martin;
Appeared in: IEEE Latin America Transactions
Publication date: Mar 2017, volume: 15, issue:3, pages: 408 - 414
Publisher: IEEE
 
» A Modified Tolles–Lawson Model Robust to the Errors of the Three-Axis Strapdown Magnetometer
Abstract:
The estimating of the Tolles–Lawson model’s coefficients plays an important role in aeromagnetic compensation. The directional cosines, which are indispensable for estimating the coefficients, are usually measured by a three-axis strapdown magnetometer in a general aeromagnetic survey system. However, in some cases, the scalar magnetometer may have a much higher accuracy than the three-axis strapdown magnetometer. This imbalance of the measurement accuracy is then introduced into the Tolles–Lawson model and affects the estimation of the coefficients. In this letter, a modified Tolles–Lawson model is introduced to reduce the imbalance through substituting the error model of the three-axis strapdown magnetometer into the calculation of the directional cosines. The characteristics of the modified model are analyzed and the corresponding coefficient-estimating system is developed. Simulation results illustrate that the modified model is more robust to the larger errors of the three-axis strapdown magnetometer than the classical model.
Autors: Qi Han;Zhenjia Dou;Xiaojun Tong;Xiang Peng;Hong Guo;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Mar 2017, volume: 14, issue:3, pages: 334 - 338
Publisher: IEEE
 
» A Multi-Grid Iterative Method for Photoacoustic Tomography
Abstract:
Inspired by the recent advances on minimizing nonsmooth or bound-constrained convex functions on models using varying degrees of fidelity, we propose a line search multi-grid (MG) method for full-wave iterative image reconstruction in photoacoustic tomography (PAT) in heterogeneous media. To compute the search direction at each iteration, we decide between the gradient at the target level, or alternatively an approximate error correction at a coarser level, relying on some predefined criteria. To incorporate absorption and dispersion, we derive the analytical adjoint directly from the first-order acoustic wave system. The effectiveness of the proposed method is tested on a total-variation penalized Iterative Shrinkage Thresholding algorithm (ISTA) and its accelerated variant (FISTA), which have been used in many studies of image reconstruction in PAT. The results show the great potential of the proposed method in improving speed of iterative image reconstruction.
Autors: Ashkan Javaherian;Sean Holman;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Mar 2017, volume: 36, issue:3, pages: 696 - 706
Publisher: IEEE
 
» A Multi-Objective Model Oriented Mapping Approach for NoC-based Computing Systems
Abstract:
In this paper, a multi-objective, i.e., reliability, communication energy, performance, co-optimization model oriented mapping approach is proposed to find optimal mappings when applications are mapped onto network-on-chip (NoC) based reconfigurable architectures. A co-optimization model, defined as reliability efficiency model (REM), is developed to evaluate the overall reliability efficiency of a mapping. In REM, reliability efficiency is defined as the reliability profit at the same energy latency product. Based on REM, a mapping approach, referred to as priority and compensation factor oriented branch and bound (PCBB), is introduced to figure out the best mapping pattern. Two techniques, priority allocation and compensation factor utilization, are adopted to make a tradeoff between search efficiency and accuracy. Experimental results show that the proposed approach has three major contributions compared to state-of-the-art approaches. (1) PCBB is highly efficient in finding best mappings, with a 3x and 720x speedup compared to branch and bound (BB) and simulated annealing (SA). (2) PCBB is able to dynamically remap after the reconfiguration of the architecture. (3) General quantitative evaluation for reliability, communication energy and performance are made respectively before integrated into the unified model REM, whereas other similar models only touch upon two of them quantitatively.
Autors: Chen Wu;Chenchen Deng;Leibo Liu;Jie Han;Jiqiang Chen;Shouyi Yin;Shaojun Wei;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Mar 2017, volume: 28, issue:3, pages: 662 - 676
Publisher: IEEE
 
» A Multi-Solver Scheme Based on Combined Field Integral Equations for Electromagnetic Modeling of Highly Complex Objects
Abstract:
A combined field integral equation (CFIE)-based multisolver scheme is presented for electromagnetic modeling of objects with complex structures and materials. In this scheme, an object is decomposed into multiple bodies based on its material property and geometry. To model bodies with complicated materials, the finite element-boundary integral (FE-BI) method is applied. To model bodies with homogeneous or conducting materials, the method of moments is employed. Specifically, three solvers are integrated in this multi-solver scheme: the FE-BI(CFIE) for inhomogeneous objects, the CFIE for dielectric objects, and the CFIE for conducting objects. A mixed testing scheme that utilizes both the Rao–Wilton–Glisson and the Buffa–Christiansen functions is adopted to obtain a good accuracy. In the iterative solution of the combined system, the multilevel fast multipole algorithm is applied to accelerate computation and reduce memory costs, and a preconditioner based on an absorbing boundary condition is employed to speed up the convergence. In the numerical examples, the individual solvers are first demonstrated to be well conditioned and highly accurate. Then, the validity of the proposed multisolver scheme is demonstrated and its capability is shown by solving scattering problems of electrically large missilelike objects.
Autors: Jian Guan;Su Yan;Jian-Ming Jin;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Mar 2017, volume: 65, issue:3, pages: 1236 - 1247
Publisher: IEEE
 
» A Multi-Tenant Cloud-Based DC Nano Grid for Self-Sustained Smart Buildings in Smart Cities
Abstract:
Energy is one of the most valuable resources of the modern era and needs to be consumed in an optimized manner by an intelligent usage of various smart devices, which are major sources of energy consumption nowadays. With the popularity of low-voltage DC appliances such as-LEDs, computers, and laptops, there arises a need to design new solutions for self-sustainable smart energy buildings containing these appliances. These smart buildings constitute the next generation smart cities. Keeping focus on these points, this article proposes a cloud-assisted DC nanogrid for self-sustainable smart buildings in next generation smart cities. As there may be a large number of such smart buildings in different smart cities in the near future, a huge amount of data with respect to demand and generation of electricity is expected to be generated from all such buildings. This data would be of heterogeneous types as it would be generated from different types of appliances in these smart buildings. To handle this situation, we have used a cloudbased infrastructure to make intelligent decisions with respect to the energy usage of various appliances. This results in an uninterrupted DC power supply to all low-voltage DC appliances with minimal dependence on the grid. Hence, the extra burden on the main grid in peak hours is reduced as buildings in smart cities would be self-sustainable with respect to their energy demands. In the proposed solution, a collection of smart buildings in a smart city is taken for experimental study controlled by different data centers managed by different utilities. These data centers are used to generate regular alerts on the excessive usage of energy from the end users' appliances. All such data centers across different smart cities are connected to the cloud-based infrastructure, which is the overall manager for making all the decisions about energy automation in smart cities. The efficacy of the proposed scheme is evaluated with respect to various pe- formance evaluation metrics such as satisfaction ratio, delay incurred, overhead generated, and demand-supply gap. With respect to these metrics, the performance of the proposed scheme is found to be good for implementation in a realworld scenario.
Autors: Neeraj Kumar;Athanasios V. Vasilakos;Joel J. P. C. Rodrigues;
Appeared in: IEEE Communications Magazine
Publication date: Mar 2017, volume: 55, issue:3, pages: 14 - 21
Publisher: IEEE
 
» A Multichip Phase-Leg IGBT Module Bonded by Pressureless Sintering of Nanosilver Paste
Abstract:
This paper presents the design, development, and optimization of large-area die attachment by pressureless sintering of nanosilver paste. With the proposed die attachment, a high power 1200 V/150 A insulated-gate-bipolar-transistor (IGBT) module is fabricated using large-area IGBT ( mm2) and diode ( mm2) chips. The average die-shear strength of higher than 30 MPa can be obtained with the low void ratio of 1.8%. The electrical characteristics of the IGBT module using pressureless sintered nanosilver paste have been measured and compared with the commercial one using soldered Sn5Pb92.5Ag2.5. Test result shows that this IGBT module has identical static and dynamic characteristics as the commercial one. Therefore, the pressureless sintered nanosilver could be used as an alternative to high-lead solder in power module manufacturing, especially in assembling SiC- or GaN-based devices for high temperature applications.
Autors: Shancan Fu;Yunhui Mei;Xin Li;Changsheng Ma;Guo-Quan Lu;
Appeared in: IEEE Transactions on Device and Materials Reliability
Publication date: Mar 2017, volume: 17, issue:1, pages: 146 - 156
Publisher: IEEE
 
» A Multiobjective Approach for Multistage Reliability Growth Planning by Considering the Timing of New Technologies Introduction
Abstract:
This paper proposes a new multiobjective multiple stage reliability growth planning (MO-MS-RGP) model. The model is based on multiobjective consideration of developing a new product, including the cost, time, and product reliability. The number of test units, test time, and the percentage of introduced new technologies are considered as decision variables in the model. Varying reliability growth rates are considered for each subsystem in each stage. Product new technologies or contents can be completely introduced in one stage or partially introduced to the product over multiple stages. New product development time limit and budget are considered as constraints in the MO-MS-RGP model. An integrated approach is developed to formulate and solve the proposed MO-MS-RGP problem. The approach starts with a multiobjective evolutionary algorithm, called multipleobjective particle swarm optimization to find a set of Pareto optimal solutions. Then, clustering methods are applied to cluster the solutions obtained by the evolutionary algorithm. Finally, the clustered solutions are ranked using a multiple criteria decision making method. A numerical example illustrates the application of the proposed MO-MS-RGP model for the reliability growth planning optimization of a next generation engine development.
Autors: Mohammadsadegh Mobin;Zhaojun Li;Ghorbanmohammad Komaki;
Appeared in: IEEE Transactions on Reliability
Publication date: Mar 2017, volume: 66, issue:1, pages: 97 - 110
Publisher: IEEE
 
» A Multireflect-Thru Method of Vector Network Analyzer Calibration
Abstract:
We present a new method for two-port vector network analyzer (VNA) calibration, which uses multiple offset-reflect standards and a flush thru connection. Offset-reflect standards consist of sections of the same uniform transmission line with different lengths, which are terminated with the same highly reflective load. The unknown propagation constant of the transmission line and the load reflection coefficient are then determined simultaneously with the VNA calibration coefficients. We compare our method with the multiline thru-reflect-line (TRL) method and show that both methods yield similar results. Our new multireflect-thru method is solely based upon dimensional parameters of the calibration standards. Therefore, like the multiline TRL method, it can be used to establish a traceable VNA calibration. Thus, the multireflect-thru method constitutes an alternative to the multiline TRL calibration in environments in which the use of transmission lines is troublesome, such as in the case of VNAs with very small coaxial and waveguide connectors. The multireflect-thru method is also useful in on-wafer measurements since it allows us to keep a constant distance between the probes, which reduces the impact of crosstalk and speeds up automated testing.
Autors: Arkadiusz Lewandowski;Wojciech Wiatr;Dazhen Gu;Nathan D. Orloff;James Booth;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Mar 2017, volume: 65, issue:3, pages: 905 - 915
Publisher: IEEE
 
» A Multisensor Mobile Interface for Industrial Environment and Healthcare Monitoring
Abstract:
This paper presents a reconfigurable multisensor mobile interface architecture that is applicable to heterogeneous sensor applications and also easy to generate new types of combined services. The multisensor interface attributes compactness and flexibility to reconfigurable readout integrated circuits (ROICs) and migration of signal processing and computation burdens from a sensor tag to a smartphone. Two reconfigurable ROICs which were designed and fabricated in a 0.18-μm CMOS process generate raw digital data from environmental and healthcare sensors. Their detected raw data are wirelessly sent to the smartphone where real-time calibration and postprocessing are performed optimally for each sensor. In an application to industrial systems, an in-vehicle system prototype supporting combined monitoring services of air-quality and healthcare was integrated into a steering wheel cover and experimentally verified to provide real-time measurement of three environmental sensor signals and two healthcare physiological signals with the results displayed on a smartphone.
Autors: Subin Choi;Dae Jung Kim;Yun Young Choi;Kyeonghwan Park;Sung-Woo Kim;Sung Hun Woo;Jae Joon Kim;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2344 - 2352
Publisher: IEEE
 
» A Multistep Dynamic Equivalent Method for Urban Power Grid Based on District Dividing
Abstract:
With the increasing demand of electricity, the development of the urban power grid has drawn a lot of attention in China. In order to focus on the analysis of an urban power grid, the remaining part of the large-scale power grid used is to be reduced. The accuracy of the equivalence is key to urban power grid research. In this paper, a multistep dynamic equivalent method based on district dividing is proposed. Based on the electrical distance, voltage level, and geographic location, the external system is divided into outer layer, inner layer, and buffer subsystem. Each district is separately reduced by different methods. The proposed technique is illustrated by a real large-scale power grid in the south of China.
Autors: Xiaoyan Yu;Ke-Jun Li;Mingqiang Wang;Zhuo-di Wang;Kaiqi Sun;Jie Lou;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 908 - 917
Publisher: IEEE
 
» A Near BER-Optimal Decoding Algorithm for Convolutionally Coded Relay Channels With the Decode-and-Forward Protocol
Abstract:
Relay-assisted communication has been shown to be an effective technique to improve the reliability and throughput of real-world wireless communication networks. It enables single-antenna users to form a virtual antenna array without installing multiple antennas at the transmitter or the receiver. This paper re-examines the decoding problem in the convolutionally coded relay channel with the classical decode-and-forward protocol. By tackling the challenge of modeling the error propagation effect at the relay, a near BER-optimal decoding (NBOD) algorithm at the destination is derived, assuming the availability of perfect receiver channel state information. Its decoding complexity is linear in the information block length, while the exact BER-optimal decoding algorithm with a sub-exponential complexity is still unknown. The major approximation involved in the derivation of the NBOD algorithm is the pairwise error probability approximation that causes a practically insignificant degradation from the optimal BER performance. Our simulation result confirms that the proposed NBOD algorithm can perform close to the maximum likelihood performance bound on BER in the three-node one-way relay channel scenario. In addition, we have further extended the proposed algorithm for more general single-source single-destination decode-and-forward-based relay networks. Simulation results further verify that the proposed NBOD algorithm can outperform existing decoding algorithms based on maximal-ratio combining and selective decode-and-forward in various relay channel scenarios at the cost of higher complexity.
Autors: Bin Qian;Wai Ho Mow;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1767 - 1781
Publisher: IEEE
 
» A Necessary Condition for Power Flow Insolvability in Power Distribution Systems With Distributed Generators
Abstract:
This paper proposes a necessary condition for power flow insolvability in power distribution systems with distributed generators (DGs). We show that the proposed necessary condition indicates the impending singularity of the Jacobian matrix and the onset of voltage instability. We consider different operation modes of DG inverters, e.g., constant-power and constant-current operations, in the proposed method. A new index based on the presented necessary condition is developed to indicate the distance between the current operating point and the power flow solvability boundary. Compared to existing methods, the operating condition-dependent critical loading factor provided by the proposed condition is less conservative and is closer to the actual power flow solution space boundary. The proposed method only requires the present snapshots of voltage phasors to monitor the power flow insolvability and voltage stability. Hence, it is computationally efficient and suitable to be applied to a power distribution system with volatile DG outputs. The accuracy of the proposed necessary condition and the index is validated by simulations on a distribution test system with different DG penetration levels.
Autors: Zhaoyu Wang;Bai Cui;Jianhui Wang;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1440 - 1450
Publisher: IEEE
 
» A New Buck Converter With Optimum-Damping and Dynamic-Slope Compensation Techniques
Abstract:
This paper presents a new buck converter with optimum-damping and dynamic-slope compensation techniques. The optimum-damping control is a well-known current control method, and the proposed dynamic-slope generator can achieve frequency compensation to prevent subharmonic oscillation. When the system is disturbed, the proposed dynamic-slope generator can stabilize the circuit in a single cycle. Hence, the dynamic-slope compensation can be used to replace traditional extra slope compensation in the optimum-damping-control circuit. The measured transient time of the load current is 2 μs from 50 to 500 mA, and 3 μs from 500 to 50 mA. The optimum-damping-control techniques can rapidly reach desired output voltage in 2–3 switching cycles. The experimental and simulation results confirm that the proposed approach can achieve the slope compensation and accelerate the transient response. The proposed converter has been fabricated with TSMC 0.18 μm CMOS 1P6M technology. The converter's operating frequency is 1 MHz, the maximum output current is 500 mA, and the peak power efficiency is 89.68% under 300-mA load current. The chip area is only 1.0376 mm × 1.0599 mm (include PADs).
Autors: Jiann-Jong Chen;Yuh-Shyan Hwang;Jian-Fong Liou;Yi-Tsen Ku;Cheng-Chieh Yu;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2373 - 2381
Publisher: IEEE
 
» A New Direction for III–V FETs for Mobile CPU Operation Including Burst-Mode: In0.35Ga0.65As Channel
Abstract:
In this letter, we show that conventional III–V MOSFETs with moderate/high In content channels (In0.53Ga0.47As or In0.70Ga0.30As) at scaled nodes are incompatible with mobile SoC designs, which often operate at intermediate/high (0.7 V to V) to achieve high frequency including during burst-mode. The incompatibility is due to conventional III–V FETs having too small bandgap, and thus too high leakage when operated at the increased voltages. We show that FETs with a more optimal lower In content, In0.35Ga0.65As, have the necessary combination of larger bandgap (~Si) and sufficiently high injection velocity (~2.5 times Si) to enable both low leakage and high performance (versus Si), across the entire range of mobile SoC operation. We report for the first time the growth and characterization of ultra-thin In0.35Ga0.65As FETs with a standard 1nm EOT gate dielectric. Calibrated models show that In0.35Ga0.65As enables the highest performance at very low leakages at intermediate/high in short channel FETs.
Autors: T. Rakshit;B. Obradovic;W.-E. Wang;W.-H. Kim;K.-M. Shin;S.-C. Baek;S.-W. Lee;S.-H. Kim;J.-M. Lee;D. Kim;A. Hoover;W.-B. Song;M. Cantoro;Y.-C. Heo;R. Rooyackers;S. C. Ardila;A. Vais;D. Lin;N. Collaert;M. S. Rodder;
Appeared in: IEEE Electron Device Letters
Publication date: Mar 2017, volume: 38, issue:3, pages: 314 - 317
Publisher: IEEE
 
» A New Distortion Correction Method for FMCW SAR Real-Time Imaging
Abstract:
A new and fast approach to correct distortion between the airborne frequency-modulated continuous wave synthetic aperture radar (FMCW SAR) real-time images is proposed in this letter. The main idea of the proposed method contains two parts. First, the rotation distortion, according to the adjacent subimages caused by the selection of the reference trajectory, is efficiently corrected by data reposition. Comparing with the conventional correction technique, the time consumption is dramatically reduced from 0.3 s to only 0.717 ms. Second, the residual offset error between the rotated subimages is analyzed and compensated in the first-step motion compensation. With the application of the proposed method, the distortion correction during FMCW SAR real-time imaging becomes realizable. The correction approach has been evaluated by an FMCW SAR system, and the obtained results verify the feasibility and effectiveness of the proposed method.
Autors: Chengfei Gu;Wenge Chang;Xiangyang Li;Gaowei Jia;Xinqun Luan;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Mar 2017, volume: 14, issue:3, pages: 429 - 433
Publisher: IEEE
 
» A New Era for Cities with Fog Computing
Abstract:
In this article, the authors dissect the technical challenges that cities face when implementing smart city plans and outlines the design principles and lessons learned after they carried out a flagship initiative on fog computing in Barcelona. In particular, they analyze what they call the Quadruple Silo (QS) problem -- that is, four categories of silos that cities confront after deploying commercially available solutions. Those silo categories are: physical (hardware) silos, data silos, and service management silos, and the implications of the three silos in administrative silos. The authors show how their converged cloud/fog paradigm not only helps solve the QS problem, but also meets the requirements of a growing number of decentralized services -- an area in which traditional cloud models fall short. The article exposes cases in which fog computing is a must, and shows that the reasons for deploying fog are centered much more on operational requirements than on performance issues related to the cloud.
Autors: Marcelo Yannuzzi;Frank van Lingen;Anuj Jain;Oriol Lluch Parellada;Manel Mendoza Flores;David Carrera;Juan Luis Pérez;Diego Montero;Pablo Chacin;Angelo Corsaro;Albert Olive;
Appeared in: IEEE Internet Computing
Publication date: Mar 2017, volume: 21, issue:2, pages: 54 - 67
Publisher: IEEE
 
» A New Framework for the Performance Analysis of Wireless Communications Under Hoyt (Nakagami- $q$ ) Fading
Abstract:
We present a novel relationship between the distribution of circular and non-circular complex Gaussian random variables. Specifically, we show that the distribution of the squared norm of a non-circular complex Gaussian random variable, usually referred to as the squared Hoyt distribution, can be constructed from a conditional exponential distribution. From this fundamental connection we introduce a new approach, the Hoyt transform method, that allows to analyze the performance of a wireless link under Hoyt (Nakagami-) fading in a very simple way. We illustrate that many performance metrics for Hoyt fading can be calculated by leveraging well-known results for Rayleigh fading and only performing a finite-range integral. We use this technique to obtain novel results for some information and communication-theoretic metrics in Hoyt fading channels.
Autors: Juan M. Romero-Jerez;F. Javier Lopez-Martinez;
Appeared in: IEEE Transactions on Information Theory
Publication date: Mar 2017, volume: 63, issue:3, pages: 1693 - 1702
Publisher: IEEE
 
» A New High-Switching-Frequency Modulation Technique to Improve the DC-Link Voltage Utilization in Multilevel Converters
Abstract:
This paper presents a new high-frequency modulation method for multilevel converters. The proposed method provides a broad linear operating range and can be digitally implemented with minimal computational effort. This modulation method creates a phase voltage composed of a rectangular component superimposed on the top of a quasi-square-shaped reference function. The reference functions are defined such that the utilization of the dc-link voltage is maximized in any modulation index, while the dv/dt of the switches is always the minimum possible value. In order to implement the proposed method, an update time that is much shorter than the fundamental period is defined in the algorithm for updating the rectangular components of the reference voltage. The high-frequency rectangular component can then be imposed on the reference function to generate the final switching function by switching between two voltage levels during the time between two update instances. Several experimental results are provided to evaluate the performance of the proposed method and to compare its operation to conventional methods.
Autors: Mohsen Aleenejad;Hamid Mahmoudi;Reza Ahmadi;Hossein Iman-Eini;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 1807 - 1817
Publisher: IEEE
 
» A New Method for Determining the Magnetic Properties of Solid Materials Employed in Unconventional Magnetic Circuits
Abstract:
To evaluate the quality of magnetic materials used in electrical machines, accurate material characterization is required. For common, solid (nonlaminated) ferromagnetic materials, characterization procedures such as the toroidal ring sample test method are capable of mapping electromagnetic properties with reasonable accuracy. This is true when the investigation is for solid materials to be used in conventional magnetic circuits, i.e., where the flux paths and induced eddy currents follow the more common “radial” characteristics, as in a standard rotating machine. When solid ferromagnetic materials are employed in unconventional machine structures, such as for transverse flux machines or tubular linear machines, classical methods are not capable of achieving an accurate representation of the flux conditions in the machine, thus resulting in inaccurate characterization data that usually underestimate the total loss prediction. In this paper, a new testing method is proposed to impose the correct flux conditions for solid materials (used in tubular linear machines) and accurately map the eddy current losses in the solid parts. The proposed method uses a simple experimental test setup to characterize the power loss of solid, ferromagnetic material. The basic experimental results from the new setup are compared to results from three-dimensional finite element analysis.
Autors: Ahmed Mahmood Mohammed;Tom Cox;Michael Galea;Chris Gerada;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2468 - 2475
Publisher: IEEE
 
» A New Multiobjective Modulated Model Predictive Control Method With Adaptive Objective Prioritization
Abstract:
This work proposes a new multiobjective modulated model predictive control (MPC) method for control of power electronic converters. The proposed method retains the advantages of conventional MPC methods in programing the nonlinear effects of the converter into the design calculations to improve the overall dynamic performance of the system and builds upon that by offering a new modulation technique for MPC to minimize the voltage and current ripples through by using a fixed switching frequency. To demonstrate the effectiveness of the proposed method, it has been used to overcome the stability problems caused by a constant power load in a multi converter system as a case study. Experimental results from a prototype cascaded converter system are provided to validate the theoretical outcomes.
Autors: Hamid Mahmoudi;Mohsen Aleenejad;Reza Ahmadi;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1188 - 1199
Publisher: IEEE
 
» A New Quality Metric for III–V/High-k MOS Gate Stacks Based on the Frequency Dispersion of Accumulation Capacitance and the CET
Abstract:
This letter proposes a metric to assess the quality of high-k dielectrics on III–V substrates and a benchmarking methodology for the gate stack qualification in the region of MOS device operation above threshold voltage, . The metric is based on a capacitive equivalent thickness (CET) - normalized frequency dispersion () evaluated in the accumulation region of capacitance–voltage (C–V) measurements of III–V MOS devices. is found to be CET independent, which allows for a preliminary assessment of the dielectric quality by using relatively thick layers. Several gate stacks, single layer or bi-layer, including those with Al2O3, and the recently reported ASM-imec interfacial layer (IL) with HfO2 are evaluated and compared against Si MOS devices. Using the proposed technique, a clear difference between the various deposition processes is observed. The results indicate that the quality of a single layer Al2O3 or a bi-layer stack of Al2O3/HfO2 on InGaAs is significantly lower compared with Si gate stacks while the ASM-imec IL yields a gate-stack with good performance on the proposed quality metric. In addition, these results correlate well with the reliability performance of the studied gate stacks.
Autors: Abhitosh Vais;Jacopo Franco;Koen Martens;Dennis Lin;Sonja Sioncke;Vamsi Putcha;Laura Nyns;Jan Maes;Qi Xie;Michael Givens;Fu Tang;Xiaoqiang Jiang;Anda Mocuta;Nadine Collaert;Aaron Thean;Kristin De Meyer;
Appeared in: IEEE Electron Device Letters
Publication date: Mar 2017, volume: 38, issue:3, pages: 318 - 321
Publisher: IEEE
 
» A New Space-Vector-Modulation Algorithm for a Three-Level Four-Leg NPC Inverter
Abstract:
For power conversion systems interfaced to four-wire supplies, four-leg converters have become a standard solution. A four-leg converter allows good compensation of zero-sequence harmonics and full utilisation of the dc-link voltage. These are very important features when unbalanced and/or nonlinear loads are connected to the system. This paper proposes a three-dimensional space vector modulation (SVM) algorithm and provides a comprehensive analysis of the algorithm implemented on a three-level, four-leg neutral-point-clamped converter. The algorithm allows a simple definition of the different switching patterns and enables balancing of the dc-link capacitor voltages using the redundancies of the converter states. A resonant controller is selected as the control strategy to validate the proposed SVM algorithm in a 6 kW experimental rig.
Autors: Felix Rojas;Ralph Kennel;Roberto Cardenas;Ricardo Repenning;Jon C. Clare;Matias Diaz;
Appeared in: IEEE Transactions on Energy Conversion
Publication date: Mar 2017, volume: 32, issue:1, pages: 23 - 35
Publisher: IEEE
 
» A New Synthesis and Design Method for Wideband Bandpass Filters With Generalized Unit Elements
Abstract:
A new synthesis and design method for wideband bandpass filters has been proposed using the concept of generalized unit elements (GUEs). The synthesis starts with a lumped-element LC circuit, which is obtained by some well-known circuits and classic methods, such as the ladder-type circuit and the coupling matrix method. A GUE is an equivalent circuit, which is represented by either a coupled LC circuit or a section of the transmission line coupled by stubs. In this view, an LC circuit is transformed into the transmission line circuit directly via a general network of a GUE. This contributes to the key idea behind the synthesis procedure. Detailed analysis on the GUE and its equivalent circuits are discussed in terms of the equivalent characteristic impedance and the extended Richard’s transformation. Based on these two variables, frequency and constant mapping functions are proposed to explicitly obtain characteristic impedances in the transmission line circuit. In the final part, three prototype filters, namely, the classic Chebyshev ladder-type filter, the general box-shaped Chebyshev filter of symmetrical filtering responses, and the cascaded trisection filter in an asymmetrical transmission zero distribution are designed and fabricated, respectively. All the experimental results agree well with the predicted ones and thus it verifies the proposed synthesis and design method.
Autors: Runqi Zhang;Sha Luo;Lei Zhu;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Mar 2017, volume: 65, issue:3, pages: 815 - 823
Publisher: IEEE
 
» A New Variational Method for Bias Correction and Its Applications to Rodent Brain Extraction
Abstract:
Brain extraction is an important preprocessing step for further analysis of brain MR images. Significant intensity inhomogeneity can be observed in rodent brain images due to the high-field MRI technique. Unlike most existing brain extraction methods that require bias corrected MRI, we present a high-order and regularized variational model for bias correction and brain extraction. The model is composed of a data fitting term, a piecewise constant regularization and a smooth regularization, which is constructed on a 3-D formulation for medical images with anisotropic voxel sizes. We propose an efficient multi-resolution algorithm for fast computation. At each resolution layer, we solve an alternating direction scheme, all subproblems of which have the closed-form solutions. The method is tested on three T2 weighted acquisition configurations comprising a total of 50 rodent brain volumes, which are with the acquisition field strengths of 4.7 Tesla, 9.4 Tesla and 17.6 Tesla, respectively. On one hand, we compare the results of bias correction with N3 and N4 in terms of the coefficient of variations on 20 different tissues of rodent brain. On the other hand, the results of brain extraction are compared against manually segmented gold standards, BET, BSE and 3-D PCNN based on a number of metrics. With the high accuracy and efficiency, our proposed method can facilitate automatic processing of large-scale brain studies.
Autors: Huibin Chang;Weimin Huang;Chunlin Wu;Su Huang;Cuntai Guan;Sakthivel Sekar;Kishore Kumar Bhakoo;Yuping Duan;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Mar 2017, volume: 36, issue:3, pages: 721 - 733
Publisher: IEEE
 
» A Nine-Phase Six-Terminal Concentrated Single-Layer Winding Layout for High-Power Medium-Voltage Induction Machines
Abstract:
This paper proposes a new winding layout for high-power medium-voltage nine-phase induction machines (IMs) based on a single-layer concentrated winding layout having a unity winding factor. The machine is fundamentally an asymmetrical nine-phase IM, where phases are connected in such a way as to provide six terminals that are fed from two three-phase inverters. Compared to a conventional asymmetrical six-phase IM with the same stator and copper volumes, it provides improved torque density, a higher torque/current ratio, and a simpler winding layout. Finite-element simulation is used to compare the proposed winding layout with a conventional split-phase six-phase IM to assess the claimed merits. A 1.5-hp prototype IM is also used for experimental verification. The experimental results are given under both healthy and fault conditions, where the faulty converter is completely disabled. The achievable derating factors under this case are then given and compared with those of conventional six-phase IMs.
Autors: Ayman S. Abdel-Khalik;Shehab Ahmed;Ahmed M. Massoud;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 1796 - 1806
Publisher: IEEE
 
» A Non-Orthogonal Multiple-Access Scheme Using Reliable Physical-Layer Network Coding and Cascade-Computation Decoding
Abstract:
This paper studies non-orthogonal transmission over a -user fading multiple access channel. We propose a new reliable physical-layer network coding and cascade-computation decoding scheme. In the proposed scheme, single-antenna users encode their messages by the same practical channel code and QAM modulation, and transmit simultaneously. The receiver chooses linear coefficient vectors and computes the associated layers of finite-field linear message combinations in a cascade manner. Finally, the users’ messages are recovered by solving the linear equations. The proposed can be regarded as a generalized onion peeling. We study the optimal network coding coefficient vectors used in the cascade computation. Numerical results show the performance of the proposed approaches that of the iterative maximum probability detection and decoding scheme, but without using receiver iteration. This results in considerable complexity reduction, processing delay, and easier implementation. Our proposed scheme significantly outperforms the iterative detection and decoding scheme with a single iteration, for example, by 1.7 dB for the two user case. The proposed scheme provides a competitive solution for non-orthogonal multiple access.
Autors: Tao Yang;Lei Yang;Y. Jay Guo;Jinhong Yuan;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1633 - 1645
Publisher: IEEE
 
» A Non-Stationary Mobile-to-Mobile Channel Model Allowing for Velocity and Trajectory Variations of the Mobile Stations
Abstract:
In mobile-to-mobile (M2M) communication systems, both the transmitter and the receiver are moving with a certain velocity, which is usually assumed to be constant over time. However, in realistic propagation scenarios, the velocity of the mobile stations (MSs) is subject to changes resulting in a non-stationary fading process. In this paper, we develop a non-stationary narrow-band M2M multipath fading channel model, where the transmitter and the receiver experience changes in their velocities and trajectories. For this model, we derive expressions for the local autocorrelation function (ACF), the Wigner–Ville spectrum, the local average Doppler shift, and the local Doppler spread under isotropic scattering conditions. In addition, we investigate the correlation properties of the proposed model assuming non-isotropic scattering around the MSs. By relaxing the standard assumption of constant velocities of the MSs, this paper shows that the local ACF and the Wigner–Ville spectrum differ completely from known expressions derived for wide-sense stationary M2M channel models. Furthermore, it is shown that our model provides consistent results with respect to the Doppler spread. The proposed channel model is useful for the performance analysis of M2M communication systems under non-stationary conditions caused by velocity variations of the MSs.
Autors: Wiem Dahech;Matthias Pätzold;Carlos A. Gutiérrez;Néji Youssef;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1987 - 2000
Publisher: IEEE
 
» A Novel 4-DOF Hybrid Magnetic Bearing for DGMSCMG
Abstract:
In this paper, a novel structure of four degrees of freedom (4-DOF) hybrid magnetic bearing is proposed for double gimbal magnetically suspended control momentum gyro (DGMSCMG). It includes two active parts and one passive part, and every active part has eight stator magnetic poles around the circumference in X and Y directions, which are divided into upper and lower layers. The passive part has two whole magnetic rings, which is located in the middle of this 4-DOF hybrid magnetic bearing. The radial active force is analyzed by equivalent magnetic circuit method (EMCM) and the axial resilience force is analyzed by the infinitesimal method based on the end magnetic flux. Meanwhile, three-dimensional finite-element model of the 4-DOF hybrid magnetic bearing is established with ANSYS software, and the radial displacement versus radial force, the current versus radial force, and the axial displacement versus axial resilience force characteristics are analyzed compared with the EMCM. Furthermore, the 10 Nms DGMSCMG prototype with the proposed 4-DOF hybrid magnetic bearing is manufactured, and the experiments of the radial active force test and the axial resilience force test are carried out. Experimental results show that the presented 4-DOF hybrid magnetic bearing has good force performance and verify the correctness of the theoretical analysis.
Autors: Jinji Sun;Ziyan Ju;Cong Peng;Yun Le;Hongliang Ren;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2196 - 2204
Publisher: IEEE
 
» A Novel and Fast SimRank Algorithm
Abstract:
SimRank is a widely adopted similarity measure for objects modeled as nodes in a graph, based on the intuition that two objects are similar if they are referenced by similar objects. The recursive nature of SimRank definition makes it expensive to compute the similarity score even for a single pair of nodes. This defect limits the applications of SimRank. To speed up the computation, some existing works replace the original model with an approximate model to seek only rough solution of SimRank scores. In this work, we propose a novel solution for computing all-pair SimRank scores. In particular, we propose to convert SimRank to the problem of solving a linear system in matrix form, and further prove that the system is non-singular, diagonally dominate, and symmetric definite positive (for undirected graphs). Those features immediately lead to the adoption of Conjugate Gradient (CG) and Bi-Conjugate Gradient (BiCG) techniques for efficiently computing SimRank scores. As a result, a significant improvement on the convergence rate can be achieved; meanwhile, the sparsity of the adjacency matrix is not damaged all the time. Inspired by the existing common neighbor sharing strategy, we further reduce the computational complexity of the matrix multiplication and resolve the scalable issues. The experimental results show our proposed algorithms significantly outperform the state-of-the-art algorithms.
Autors: Juan Lu;Zhiguo Gong;Xuemin Lin;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Mar 2017, volume: 29, issue:3, pages: 572 - 585
Publisher: IEEE
 
» A Novel Broadband Dual Circularly Polarized Microstrip-Fed Monopole Antenna
Abstract:
A broadband dual circularly polarized (CP) planar monopole antenna is presented in this communication. The antenna is fed by dual orthogonal microstrip lines for polarization diversity. Circular polarization is achieved with a modified ground-plane structure and the isolation between the ports is improved by extending a protruded strip between the feed lines. L-shaped strips (LSSs) and inverted LSSs are designed along the radiating edges of the monopole. The combination of these two strips maximizes the axial ratio (AR) bandwidth, when they are placed /4 apart at center frequency of the CP band. This principle is verified by fabricating the prototype on a 1-mm-thick FR4 substrate with 32 mm mm lateral dimension. From the experimental results, it is observed that the 3-dB AR bandwidth of the proposed antenna is 80.7% (3.74–8.8 GHz). The gain, return loss, and port isolation are higher than 1, 10, and 20 dB, respectively, within the CP band.
Autors: Chandu DS;S. S. Karthikeyan;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Mar 2017, volume: 65, issue:3, pages: 1410 - 1415
Publisher: IEEE
 
» A Novel Cache-Utilization-Based Dynamic Voltage-Frequency Scaling Mechanism for Reliability Enhancements
Abstract:
We propose a cache architecture using a 7T/14T SRAM (Fujiwara et al., 2009) and a control mechanism for reliability enhancements. Our control mechanism differs from conventional dynamic voltage-frequency scaling (DVFS) methods in that it considers not only the cycles per instruction behaviors but also the cache utilization. To measure cache utilization, a novel metric is proposed. The experimental results show that our proposed method achieves 1000 times less bit-error occurrences compared with conventional DVFS methods under the ultralow-voltage operation. Moreover, the results indicate that our proposed method surprisingly not only incurs no performance and energy overheads but also achieves on average a 2.10% performance improvement and a 6.66% energy reduction compared with conventional DVFS methods.
Autors: Yen-Hao Chen;Yi-Lun Tang;Yi-Yu Liu;Allen C.-H. Wu;TingTing Hwang;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Mar 2017, volume: 25, issue:3, pages: 820 - 832
Publisher: IEEE
 
» A Novel Centralized PV Power Plant Controller for Reducing the Voltage Unbalance Factor at Transmission Level Interconnection
Abstract:
This paper presents a novel centralized positive and negative sequence control strategy for enhancing the unbalanced operation of electric transmission networks. The proposed control strategy is deployed as an effective ancillary service provided by a photovoltaic power plants. The excess capacity of grid-tied inverters is utilized based on a novel centralized positive and negative sequence reactive current division algorithm. The control strategy dynamically allocates the amount of reactive power compensated by each inverter in the power plant according to its active power generation level. The performance of the proposed control strategy is evaluated for a photovoltaic power plant connected to the IEEE 12-bus Flexible AC Transmission Systems test system in steady-state and transient operation. This is demonstrated through unbalanced loads and asymmetrical grid faults. The proposed control strategy effectively reduced the voltage unbalance factor within the acceptable operating limits, and enhanced the transient response at the transmission level interconnection. This is achieved in order to adhere to grid codes’ requirements and the IEC 61000-3-13 standard.
Autors: Nada Al Awadhi;Mohamed Shawky El Moursi;
Appeared in: IEEE Transactions on Energy Conversion
Publication date: Mar 2017, volume: 32, issue:1, pages: 233 - 243
Publisher: IEEE
 
» A Novel Class of Robust Covert Channels Using Out-of-Order Packets
Abstract:
Covert channels are usually used to circumvent security policies and allow information leakage without being observed. In this paper, we propose a novel covert channel technique using the packet reordering phenomenon as a host for carrying secret communications. Packet reordering is a common phenomenon on the Internet. Moreover, it is handled transparently from the user and application-level processes. This makes it an attractive medium to exploit for sending hidden signals to receivers by dynamically manipulating packet order in a network flow. In our approach, specific permutations of successive packets are selected to enhance the reliability of the channel, while the frequency distribution of their usage is tuned to increase stealthiness by imitating real Internet traffic. It is very expensive for the adversary to discover the covert channel due to the tremendous overhead to buffer and sort the packets among huge amount of background traffic. A simple tool is implemented to demonstrate this new channel. We studied extensively the robustness and capabilities of our proposed channel using both simulation and experimentation over large varieties of traffic characteristics. The reliability and capacity of this technique have shown promising results. We also investigated a practical mechanism for distorting and potentially preventing similar novel channels.
Autors: Adel El-Atawy;Qi Duan;Ehab Al-Shaer;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Mar 2017, volume: 14, issue:2, pages: 116 - 129
Publisher: IEEE
 
» A Novel DC Arc Fault Detection Method Based on Electromagnetic Radiation Signal
Abstract:
Because of lack of current zero, dc arc is hard to be extinguished, which has become the main reason causing faults in dc system. To find an effective method to detect dc arc faults is of great significance. In this paper, a method for detecting dc arc fault based on electromagnetic radiation signal is presented. A dc arc generating device is designed to simulate dc arc faults caused by loose connection in dc systems. A fourth-order Hilbert curve fractal antenna is adopted to detect the electromagnetic radiation signals of dc arc. The amplitude and spectrums of electromagnetic radiation signals measured under different circuit currents are analyzed. A photovoltaic (PV) system is constructed and the dc arc generated in that system is measured. The test results show that, under the present experimental condition, the electromagnetic radiation pulses have an obvious characteristic frequency, which are in a range of 39–41 MHz. The characteristic frequency of electromagnetic radiation of dc arc generated in PV system is around 39 MHz. Moreover, the characteristic frequency of dc arc is compared with that of switch operation. The dc arc has higher characteristic frequency and longer interval of each electromagnetic radiation pulse than those of the switch operation. The results indicate that the characteristic frequency of electromagnetic radiation signals can be used as the detection parameter of dc arc.
Autors: Qing Xiong;Shengchang Ji;Lingyu Zhu;Lipeng Zhong;Yuan Liu;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Mar 2017, volume: 45, issue:3, pages: 472 - 478
Publisher: IEEE
 
» A Novel Design Method of Permanent Magnet Synchronous Generator From Perspective of Permanent Magnet Material Saving
Abstract:
This paper puts forward a novel design method of permanent magnet synchronous generator (PMSG). The most significant advantage of this method is that the output power of PMSG can be prominently improved without increasing any material costs. The main difference from the traditional design scheme is that the volume of permanent magnet (PM) remains unchanged during the entire design procedure. And the maximum output power scheme is found out just by optimizing the PM's shapes with the change of mechanical pole-arc coefficient. In other words, this method aims to obtain the maximum PM utilization design scheme that can produce more “effective” magnet field so that it can generate the larger output power. The dimension parameters of PMs with different shapes are calculated by the equivalent analytic geometry method. To verify its availability, this novel method is performed on four common types of PMSGs with different rotor structures, and their satisfactory performance results are obtained. The comparison with the traditional machine design scheme is also presented to illustrate the innovation and priority. The finite-element analysis method based on Ansoft/Maxwell is applied for the electromagnetic models’ building and simulation.
Autors: Hongwei Fang;Dan Wang;
Appeared in: IEEE Transactions on Energy Conversion
Publication date: Mar 2017, volume: 32, issue:1, pages: 48 - 54
Publisher: IEEE
 
» A Novel Doppler Chirp Rate and Baseline Estimation Approach in the Time Domain Based on Weighted Local Maximum-Likelihood for an MC-HRWS SAR System
Abstract:
In this letter, a novel estimation approach for the Doppler chirp rate and baseline in azimuth is proposed for the multichannel in azimuth high-resolution and wide-swath (HRWS) synthetic aperture radar (SAR) system. First, a range-invariant Doppler chirp rate estimation approach is developed based on a map drift algorithm and correlation function method. Then, a weighted local maximum-likelihood approach is adopted to obtain an accurate estimation of the range-variant Doppler chirp rate. With an accurate Doppler chirp rate, the baseline in azimuth can be estimated, which is developed from the correlation function between the echoes of adjective channels. The proposed approaches are successfully applied to process real five-channel HRWS SAR echo data, demonstrating the efficacy of the proposed methods.
Autors: Shuangxi Zhang;Mengdao Xing;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Mar 2017, volume: 14, issue:3, pages: 299 - 303
Publisher: IEEE
 
» A Novel Fall Prediction System on Smartphones
Abstract:
The elderly person’s life is almost full of hazards. Especially, the fall risk is one of the problems caused by the elderly and the people using prostheses. This paper aims to develop a fall prediction system on smartphones. The proposed App system can record users’ gait data sets with which their gait statuses regarding stability and symmetry are analyzed. A high-level fuzzy Petri net model is used to identify the human’s actions, including normal action, sport, and fall risk. The experimental results indicate that there are high successful predictions obtained by the proposed App system. Thus, it can easily increase the fall risk prevention.
Autors: Rong-Kuan Shen;Cheng-Ying Yang;Victor R. L. Shen;Wei-Cheng Chen;
Appeared in: IEEE Sensors Journal
Publication date: Mar 2017, volume: 17, issue:6, pages: 1865 - 1871
Publisher: IEEE
 
» A Novel Flux-Switching Permanent Magnet Machine With Overlapping Windings
Abstract:
In this paper, in order to enlarge its torque density, an overlapping winding (OW) is applied to the 24/16-stator/rotor-pole flux-switching permanent magnet (FSPM) machine. By adopting an OW-configuration with full-pitch coils, the pitch factor and coil-flux cross-sectional area in the 24/16-pole FSPM machine with nonoverlapping winding (NOW) can be doubled. Thus, the fundamental open-circuit phase flux-linkage and back-EMF can be effectively enhanced by 115.28%, making it comparable to the conventional 12/10-pole NOW-FSPM machine. Therefore, by injecting the same current density, the proposed OW-FSPM machine can produce 65.2% higher torque density than its NOW counterpart, and 17.6% higher torque density than the conventional 12/10-pole NOW machine despite 21.5% lower ampere turns due to a smaller slot area. However, the proposed machine suffers from high torque ripple due to high cogging torque and back-EMF harmonics. Torque ripple reduction by harmonics current injection and rotor skewing in the proposed machine are investigated. Results show that both methods can effectively reduce the torque ripple in the proposed 24/16-pole NOW-FSPM machine, albeit with the level of torque density being compromised. Experiments are performed in order to validate the analysis.
Autors: Lingyun Shao;Wei Hua;Z. Q. Zhu;Xiaofeng Zhu;Ming Cheng;Zhongze Wu;
Appeared in: IEEE Transactions on Energy Conversion
Publication date: Mar 2017, volume: 32, issue:1, pages: 172 - 183
Publisher: IEEE
 
» A Novel Four-Dimensional Hyperchaotic Four-Wing System With a Saddle–Focus Equilibrium
Abstract:
A novel 4-D hyperchaotic four-wing system with a saddle–focus equilibrium is introduced in this brief. The qualitative analysis of the proposed system confirms its complex dynamic behavior, which is studied by using well-known numerical tools of nonlinear theory, such as the bifurcation diagram, Lyapunov exponents, Poincaré maps, and phase portraits. Furthermore, the novel hyperchaotic system is experimentally emulated by an electronic circuit, and its dynamic behavior is studied to confirm the feasibility of the theoretical model.
Autors: Christos Volos;Jamal-Odysseas Maaita;Sundarapandian Vaidyanathan;Viet-Thanh Pham;Ioannis Stouboulos;Ioannis Kyprianidis;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Mar 2017, volume: 64, issue:3, pages: 339 - 343
Publisher: IEEE
 
» A Novel Framework of Multi-Hop Wireless Charging for Sensor Networks Using Resonant Repeaters
Abstract:
Wireless charging has provided a convenient alternative to renew nodes’ energy in wireless sensor networks. Due to physical limitations, previous works have only considered recharging a single node at a time, which has limited efficiency and scalability. Recent advances on multi-hop wireless charging is gaining momentum and provides fundamental support to address this problem. However, existing single-node charging designs do not consider and cannot take advantage of such opportunities. In this paper, we propose a new framework to enable multi-hop wireless charging using resonant repeaters. First, we present a realistic model that accounts for detailed physical factors to calculate charging efficiencies. Second, to achieve balance between energy efficiency and data latency, we propose a hybrid data gathering strategy that combines static and mobile data gathering to overcome their respective drawbacks and provide theoretical analysis. Then, we formulate multi-hop recharge schedule into a bi-objective NP-hard optimization problem. We propose a two-step approximation algorithm that first finds the minimum charging cost and then calculates the charging vehicles’ moving costs with bounded approximation ratios. Finally, upon discovering more room to reduce the total system cost, we develop a post-optimization algorithm that iteratively adds more stopping locations for charging vehicles to further improve the results while ensuring none of the nodes will deplete battery energy. Our extensive simulations show that the proposed algorithms can handle dynamic energy demands effectively, and can cover at least three times of nodes and reduce service interruption time by an order of magnitude compared to the single-node charging scheme.
Autors: Cong Wang;Ji Li;Fan Ye;Yuanyuan Yang;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Mar 2017, volume: 16, issue:3, pages: 617 - 633
Publisher: IEEE
 
» A Novel Indicator for Mechanical Failure and Life Prediction Based on Debris Monitoring
Abstract:
Since failure of mechanical components can lead to catastrophic failure of the entire system, significant efforts have been made to monitor system behavior and try to predict the end of useful life of a component. A method to assess the process of mechanical wear in real time is based on monitoring the amount of debris in the lubricant. Although this approach has shown some potential in application, the nonlinearly cumulative damage in the late stage of mechanical life presents significant challenge to early prediction of the Remaining Useful Life. This paper considers continuous wear (devoid of sudden large particle dislodging or catastrophic failure) and assumes that it is a positive feedback physical process. This assumption serves as a basis of a dynamic model developed to describe the nonlinear behavior of wear in the late stage of useful mechanical life. Based on this model, it was discovered that the inflection point in the cumulative debris, during continuous wear process, presents a more accurate indicator of pending mechanical failure compared to the existing indicators. The peak in generation rate is considered as the end of useful mechanical life. The model is validated based on data from four wind turbine gearboxes. The results indicate that the proposed model and associated indicator can be used with significant confidence to predict the Remaining Useful Life during the early stages of operation and have distinct advantages over the standard linear model (Moving Average Model), both in terms of accuracy and robustness.
Autors: Wei Hong;Shaoping Wang;Mileta M. Tomovic;Haokuo Liu;Jian Shi;Xingjian Wang;
Appeared in: IEEE Transactions on Reliability
Publication date: Mar 2017, volume: 66, issue:1, pages: 161 - 169
Publisher: IEEE
 
» A Novel MPPT Technique Based on an Image of PV Modules
Abstract:
PV modules operating under partially shaded conditions exhibit multiple peaks in their output power curves, which cause the majority of the maximum power point tracking (MPPT) techniques to become trapped in a local power peak. This unfortunately leads to additional energy losses that could otherwise be harvested if the global maximum power peak (GMPP) were correctly tracked. The available MPPT methods that are able to track the GMPP require periodic scanning of the PV curve, which disturbs the operation of the system and causes energy losses. A new MPPT technique is proposed in this paper that is distinguished by its ability to find the GMPP without the need for periodic curve scanning. The proposed method utilizes the mathematical model of the PV module, as well as the irradiances received by its PV cells, to analytically calculate the location of the GMPP. The required irradiances are innovatively estimated using an image of the PV module captured by an optical camera. The proposed method is also combined with the perturb and observe method to compensate for errors in the model or irradiance estimation. Experimental verifications are conducted to validate the effectiveness of the proposed MPPT method under various shading scenarios.
Autors: Yousef Mahmoud;Ehab F. El-Saadany;
Appeared in: IEEE Transactions on Energy Conversion
Publication date: Mar 2017, volume: 32, issue:1, pages: 213 - 221
Publisher: IEEE
 
» A Novel Multiterminal VSC-HVdc Transmission Topology for Offshore Wind Farms
Abstract:
Multiterminal voltage source converter (VSC) topologies of high voltage direct current (HVdc) transmission systems (M-HVdc) for the integrating large offshore wind farms are scrutinized. A novel two wind farm with one onshore substation (2WF-1SS) topology is proposed. M-HVdc system standards are defined along with control schemes. HVdc switch gear and HVdc-link topologies are reviewed, considering the need of HVdc circuit breakers, dc cables, and extra offshore substations. Numerous M-HVdc-link topologies are analyzed and compared based on certain techno-economic criteria: length, number and ratings of HVdc circuits, cost, flexibility, stability, number of HVdc circuit breakers, and offshore substations. Operation of various topologies with respect to the designed control system is analyzed and compared through PSCAD/EMTDC simulations considering two different tests: permanent VSC disconnection and a dc line-to-line fault. Results show that 2WF-1SS is a promising topology for future multiterminal HVdc grids.
Autors: Ali Raza;Xu Dianguo;Su Xunwen;Li Weixing;Barry W. Williams;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1316 - 1325
Publisher: IEEE
 
» A Novel Pathway Analysis Approach Based on the Unexplained Disregulation of Genes
Abstract:
A crucial step in the understanding of any phenotype is the correct identification of the signaling pathways that are significantly impacted in that phenotype. However, most current pathway analysis methods produce both false positives as well as false negatives in certain circumstances. We hypothesized that such incorrect results are due to the fact that the existing methods fail to distinguish between the primary dis-regulation of a given gene itself and the effects of signaling coming from upstream. Furthermore, a modern whole-genome experiment performed with a next-generation technology spends a great deal of effort to measure the entire set of 30000–100000 transcripts in the genome. This is followed by the selection of a few hundreds differentially expressed genes, step that literally discards more than 99% of the collected data. We also hypothesized that such a drastic filtering could discard many genes that play crucial roles in the phenotype. We propose a novel topology-based pathway analysis method that identifies significantly impacted pathways using the entire set of measurements, thus allowing the full use of the data provided by NGS techniques. The results obtained on 24 real data sets involving 12 different human diseases, as well as on 8 yeast knock-out data sets show that the proposed method yields significant improvements with respect to the state-of-the-art methods: SPIA, GSEA, and GSA. Availability: Primary dis-regulation analysis is implemented in R and included in ROntoTools Bioconductor package (versions 2.0.0). https://www.bioconductor.org/packages/release/bioc/html/ROntoTools.html.
Autors: Sahar Ansari;Calin Voichita;Michele Donato;Rebecca Tagett;Sorin Draghici;
Appeared in: Proceedings of the IEEE
Publication date: Mar 2017, volume: 105, issue:3, pages: 482 - 495
Publisher: IEEE
 
» A Novel Quantitative 500-MHz Acoustic Microscopy System for Ophthalmologic Tissues
Abstract:
Objective: This paper describes development of a novel 500-MHz scanning acoustic microscope (SAM) for assessing the mechanical properties of ocular tissues at fine resolution. The mechanical properties of some ocular tissues, such as lamina cribrosa (LC) in the optic nerve head, are believed to play a pivotal role in eye pathogenesis. Methods: A novel etching technology was used to fabricate silicon-based lens for a 500-MHz transducer. The transducer was tested in a custom-designed scanning system on human eyes. Two-dimensional (2-D) maps of bulk modulus (K) and mass density (ρ) were derived using improved versions of current state-of-the-art signal processing approaches. Results: The transducer employed a lens radius of 125 μm and had a center frequency of 479 MHz with a –6-dB bandwidth of 264 MHz and a lateral resolution of 4 μm. The LC, Bruch's membrane (BM) at the interface of the retina and choroid, and Bowman's layer (BL) at the interface of the corneal epithelium and stroma, were successfully imaged and resolved. Analysis of the 2-D parameter maps revealed average values of LC, BM, and BL with ; GPa, ; GPa, ; GPa, ρ g/cm3; ρ g/cm3; ρ g/cm3. Significance: This novel SAM was shown to be capable of measuring mechanical properties of soft biological tissues at microscopic resolution; it is currently the only system that allows simultaneous measurement of K, ρ, and attenuation in large lateral scales (field area >9 mm2) and at fine resolutions.
Autors: Daniel Rohrbach;Anette Jakob;Harriet O. Lloyd;Steffen H. Tretbar;Ronald H. Silverman;Jonathan Mamou;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Mar 2017, volume: 64, issue:3, pages: 715 - 724
Publisher: IEEE
 
» A Novel SDN-Based Architecture to Provide Synchronization as a Service in 5G Scenarios
Abstract:
Moving toward 5G, network synchronization is expected to play a key role in the successful deployment of the new mobile communication networks. This article presents an application of SDN (software defined networking) and NFV (network function virtualization) principles to the network synchronization area, making it possible to offer synchronization as a service. The approach is based on defining a harmonization layer that orchestrates radio and heterogeneous transport domains by means of a suitable subset of abstracted information exchanged among the domains, and by making use of virtualized synchronization functions.
Autors: Stefano Ruffini;Paola Iovanna;Mats Forsman;Tomas Thyni;
Appeared in: IEEE Communications Magazine
Publication date: Mar 2017, volume: 55, issue:3, pages: 210 - 216
Publisher: IEEE
 
» A Novel SuperSteep Subthreshold Slope Dual-Channel FET Utilizing a Gate-Controlled Thyristor Mode-Induced Positive Feedback Current
Abstract:
For the first time, we experimentally demonstrate an FET with a polycrystalline silicon (poly-Si) device featuring supersteep subthreshold slope (SS) around 20 mV/decade at room temperature. This novel dual-channel device is a three-wordline (WL) transistor fabricated in a poly-Si channel, with p+ source and n+ drain. The outer two WLs serve as the pass gates that control the virtual junction of the center WL device (main gate). Whether n-channel or p-channel characteristics are achieved depend on the bias polarity applied to the pass gates. Both read modes exhibit supersteep SS behavior for the center main gate. Theoretical analysis suggests that this three-WL FET device creates a gate-controlled thyristor mode, where a positive feedback current is induced when the center main gate voltage is above the onset value to induce the turned-on thyristor. Different from the usual tunneling FET (with reverse-biased junction bias), the p+/n+ junction is forward biased, and thus, the read current can approach even for a narrow-width (~32 nm) poly-Si thin-film transistor, amounting to 0.3-mA/ drive current. This device displays no hysteresis between forward and reverse voltage sweeping, and the steep SS has weak temperature/size dependence.
Autors: Wei-Chen Chen;Hang-Ting Lue;Yi-Hsuan Hsiao;Chih-Yuan Lu;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1336 - 1342
Publisher: IEEE
 
» A Novel TCAD-Based Thermal Extraction Approach for Nanoscale FinFETs
Abstract:
Self-heating and thermal modeling in fin-shaped FETs (FinFETs) are studied in this brief using calibrated 3-D TCAD simulations. Using the second order network extraction, we demonstrate for the first time a simple method for the modeling of thermal resistances and capacitances for BSIMCMG compact models using small-signal ac capacitance method. We show that the extraction of thermal time constants using the second-order method is superior to the other techniques used in the literature. Using this technique, we extract the thermal time constants for FinFETs to be in the order of a few nano/pico seconds.
Autors: U. Sajesh Kumar;V. Ramgopal Rao;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1404 - 1407
Publisher: IEEE
 
» A Novel Thermally Evaporated Etching Mask for Low-Damage Dry Etching
Abstract:
Dry etching is widely used for nanofabrication and it requires reliable etching masks. However, hard dry etching masks usually need high temperature and/or plasma deposition, which may cause damage to temperature-sensitive materials and semiconductor surface. Here, we develop a novel etching mask material, silicon monoxide (SiO), which is thermally evaporated and hence can avoid such drawbacks. The etching selectivity of evaporated SiO is shown to be higher than 50:1, comparable to sputtered SiO2. A nanochannel device, called self-switching diode (SSD), is fabricated to evaluate the mask-deposition-process damage because of its high sensitivity to surface states. In comparison to commonly used sputtered SiO2 and polymethyl methacrylate mask, the SSD fabricated using evaporated SiO exhibits the highest channel conductance, the strongest nonlinearity, and the best high-frequency performance. Hall measurements also reveal that the carrier mobility of nanochannels etched with SiO mask is twice that of similar channels with SiO2 mask.
Autors: Hanbin Wang;Yiming Wang;Gengchang Zhu;Qingpu Wang;Qian Xin;Lin Han;Aimin Song;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Mar 2017, volume: 16, issue:2, pages: 290 - 295
Publisher: IEEE
 
» A Novel Weak Signal Detection Method via Chaotic Synchronization Using Chua's Circuit
Abstract:
This paper presents a novel detection method for weak sinusoidal signal embedded in strong noise. Two synchronization systems are constructed to implement this method, in which one is used to estimate the frequency and phase angle, the other is used to estimate the amplitude. The detection process is achieved in three steps. First, two synchronization systems are established based on chaotic synchronization theorem and adaptive algorithm. The test signal is injected into their driving ends. Second, in the first synchronization system, the frequency of the sinusoidal signal is obtained by the MUSIC algorithm. Then, the reference sinusoidal signal with this frequency can be generated and correlated with the test signal. The phase difference between them is obtained. Finally, in the second synchronization system, the amplitude of the reference signal is close to the actual amplitude of the sinusoidal signal in the process of synchronization. This detection system is achieved by the Chua's circuit, and its detection characteristics are verified by simulation and experimentation. The results show that it is feasible to obtain the parameters of the sinusoidal signal. It retains excellent detection performance, simplifies parameters setting, avoids the solution of the running state, and is easy to achieve.
Autors: Guozheng Li;Bo Zhang;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2255 - 2265
Publisher: IEEE
 
» A Novel Web-Based Approach for Visualization and Inspection of Reading Difficulties on University Students
Abstract:
Existing tools aim to detect university students with early diagnosis of dyslexia or reading difficulties, but there are not developed tools that let those students better understand some aspects of their difficulties. In this paper, a dashboard for visualizing and inspecting early detected reading difficulties and their characteristics, called PADA (acronym for the Spanish name Panel de Analíticas de Aprendizaje de Dislexia en Adultos), is presented. PADA is a web-based tool designed to facilitate the creation of descriptive visualizations required for a better understanding by students about their learner model. Through information visualization techniques, PADA shows students the knowledge in their learner models in order to help them to increase their awareness and to support reflection and self-regulation about their difficulties in reading. PADA provides different learning analytics on reading performance of students, so that they can self-identify their strengths and weaknesses and self-regulate their learning. This paper describes examples that cover a variety of visualizations (bar-charts, line-charts, and pie-charts) to show user model fragments as personal details, reading profiles, learning styles, and cognitive traits of the students. We tested PADA with 26 students (aged 21–53 years) of different academic programs and levels, dyslexic and non-dyslexic. The results show that PADA can assist students in creating awareness, and help them to understand their difficulties associated with the reading tasks, as well as facilitate reflection and self-regulation in the learning process. Implications for the design of learning analytics are discussed and directions for future work are outlined.
Autors: Carolina Mejia;Beatriz Florian;Ravi Vatrapu;Susan Bull;Sergio Gomez;Ramon Fabregat;
Appeared in: IEEE Transactions on Learning Technologies
Publication date: Mar 2017, volume: 10, issue:1, pages: 53 - 67
Publisher: IEEE
 
» A Novel Wrapper Approach for Feature Selection in Object-Based Image Classification Using Polygon-Based Cross-Validation
Abstract:
Feature selection is becoming a major component of object-based classification as numerous features of segmented object become available. Although common feature selection methods in object-based classification are acknowledged, wrapper-based methods remain an issue due to the diversity of accuracy assessment methods. This letter presents a new wrapper approach using polygon-based cross validation (CV) to overcome possible bias of object-based accuracy assessment for object-based classification. The new method is a two-step wrapper-based feature selection that involves the integration of: 1) feature importance rank using gain ratio and 2) feature subset evaluation using a polygon-based tenfold CV within a support vector machine (SVM) classifier. Several high-resolution images, including both unmanned aerial vehicle images and ISPRS (International Society for Photogrammetry and Remote Sensing) benchmark test data, were used to test the proposed method. Results show that, with the proposed polygon-based CV SVM wrapper, the mean overall accuracy is significantly higher than with an object-based CV SVM wrapper. Furthermore, the proposed method shows potential for comprehensively considering all types of features instead of only spectral features.
Autors: Lei Ma;Manchun Li;Yu Gao;Tan Chen;Xiaoxue Ma;Lean Qu;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Mar 2017, volume: 14, issue:3, pages: 409 - 413
Publisher: IEEE
 
» A Numerical Synthesis Method for Hybrid-Type High-Power Gyrotron Launchers
Abstract:
A numerical synthesis method for the optimization of launchers with hybrid-type wall surface for high-power fusion gyrotrons is proposed in this paper. The profile of such a launcher is built from a novel combination of a periodic harmonic wall perturbation followed by a mirror-line-type deformation, so we named it hybrid-type launcher. The synthesis method has been tested to design a hybrid-type launcher to transform the TE32,9 mode of the ITER EU 1-MW gyrotron operating at 170 GHz. The simulation results show that the fundamental Gaussian mode content (FGMC) of the millimeter-wave beam at the radiating aperture of the hybrid-type launcher is approximately 99.1%. In comparison with the corresponding harmonically deformed launcher, the simulations results reveal that the launcher with hybrid-type surface contour provides higher conversion efficiency combined with low diffraction loss (0.7%). The computation time for the design of hybrid-type launchers is just half of that for mirror-line launchers. In the case of not very short launchers, hybrid-type launchers can provide high FGMCs of RF beams with low diffraction losses that are comparable with those of mirror-line launchers.
Autors: Jianbo Jin;Manfred Thumm;Gerd Gantenbein;John Jelonnek;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Mar 2017, volume: 65, issue:3, pages: 699 - 706
Publisher: IEEE
 
» A Parallel Algorithm for $N$-Way Interval Set Intersection
Abstract:
The comparison of sets of genome intervals (e.g., genes, repeats, ChIP-seq peaks) is essential to genome research, especially as modern sequencing technologies enable ever larger and more complex experiments. Relationships between genomic features are commonly identified by their intersection: that is, if feature sets contain overlapping intervals then it is inferred that they share a common biological function or origin. Using this technique, researchers identify genomic regions that are common among multiple (or unique to individuals) data sets. While there have been recent advances in algorithms for pairwise intersections between two sets of genomic intervals, few advances have been made to the intersection of many sets of genomic intervals. Identifying intersections among many interval sets is particularly important when attempting to distill biological insights from the massive, multidimensional data sets that are common to modern genome research. For such analyses, speed and efficiency are crucial, given the size and sheer number of data sets involved. To solve this problem, we present a novel “slice-then-sweep” algorithm that, given interval sets, efficiently reveals the subset of intervals that are common to all sets. We demonstrate that our algorithm is more efficient in the sequential case and has a vastly higher capacity for parallelization with a 19x speedup over the existing algorithm.
Autors: Ryan M. Layer;Aaron R. Quinlan;
Appeared in: Proceedings of the IEEE
Publication date: Mar 2017, volume: 105, issue:3, pages: 542 - 551
Publisher: IEEE
 
» A Parametric Study for the Design of an Optimized Ultrasonic Percussive Planetary Drill Tool
Abstract:
Traditional rotary drilling for planetary rock sampling, in situ analysis, and sample return are challenging because the axial force and holding torque requirements are not necessarily compatible with lightweight spacecraft architectures in low-gravity environments. This paper seeks to optimize an ultrasonic percussive drill tool to achieve rock penetration with lower reacted force requirements, with a strategic view toward building an ultrasonic planetary core drill (UPCD) device. The UPCD is a descendant of the ultrasonic/sonic driller/corer technique. In these concepts, a transducer and horn (typically resonant at around 20 kHz) are used to excite a toroidal free mass that oscillates chaotically between the horn tip and drill base at lower frequencies (generally between 10 Hz and 1 kHz). This creates a series of stress pulses that is transferred through the drill bit to the rock surface, and while the stress at the drill-bit tip/rock interface exceeds the compressive strength of the rock, it causes fractures that result in fragmentation of the rock. This facilitates augering and downward progress. In order to ensure that the drill-bit tip delivers the greatest effective impulse (the time integral of the drill-bit tip/rock pressure curve exceeding the strength of the rock), parameters such as the spring rates and the mass of the free mass, the drill bit and transducer have been varied and compared in both computer simulation and practical experiment. The most interesting findings and those of particular relevance to deep drilling indicate that increasing the mass of the drill bit has a limited (or even positive) influence on the rate of effective impulse delivered.
Autors: Xuan Li;Patrick Harkness;Kevin Worrall;Ryan Timoney;Margaret Lucas;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Mar 2017, volume: 64, issue:3, pages: 577 - 589
Publisher: IEEE
 
» A Pay-As-You-Go Methodology for Ontology-Based Data Access
Abstract:
A successfully repeated use case for Semantic Web technologies is Ontology-Based Data Access for data integration. In this approach, an ontology serves as a uniform conceptual federating model, which is accessible to both IT developers and business users. Here, two challenges for developing an OBDA system are considered: ontology and mapping engineering, along with a pay-as-you-go methodology that addresses these challenges and enables agility.
Autors: Juan F. Sequeda;Daniel P. Miranker;
Appeared in: IEEE Internet Computing
Publication date: Mar 2017, volume: 21, issue:2, pages: 92 - 96
Publisher: IEEE
 
» A PFC Modified Landsman Converter-Based PWM-Dimmable RGB HB-LED Driver for Large Area Projection Applications
Abstract:
In this paper for power factor correction (PFC), a modified Landsman converter is introduced. The application is targeted for high-brightness (HB) projection application with brightness control for HB red–green–blue (HB-RGB) light-emitting diode (LED). A pulse-width modulation (PWM) technique is used for intensity control to achieve brightness control of the LED driver. The proposed PFC converter is used to feed a dual output flyback dc–dc converter that supplies power to the forced cooling unit and the LED module with galvanic isolation. The brightness control of LED is performed by synchronous buck converter. The modified Landsman converter operates in discontinuous output inductor current mode for PFC at universal ac mains. A prototype of the proposed LED driver is experimentally verified. The performance of proposed driver is evaluated at full and light-load condition for universal ac mains (90–265 V) over a full range of brightness. The power quality parameters are found within the acceptable limits of harmonic standard IEC 61000-3-2 for universal ac mains.
Autors: Aman Kumar Jha;Bhim Singh;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1552 - 1561
Publisher: IEEE
 
» A Phase-Interpolator-Based Fractional Counter for All-Digital Fractional-N Phase-Locked Loop
Abstract:
A phase-interpolator-based fractional counter (PIFC) is proposed to reduce power consumption by replacing TDC in a ring-oscillator-based digital fractional-N phase-locked loop. A predicted-phase-interpolation method is used to calculate the integer and fractional parts of the frequency-division-ratio and to find two interpolation clocks; the prediction method gives a significant power reduction in the proposed PIFC by enabling the use of low-frequency clocks for phase interpolation. The proposed PLL chip in a 65-nm CMOS occupies 0.173 mm2 and consumes 15.5 mW at 6 GHz and 1.2 V; the PIFC consumes less than 20% of the TDC power. The integrated rms jitter is 1.75 ps and a FoM value of −223.2 dB is achieved.
Autors: Young-Ho Choi;Byungsub Kim;Jae-Yoon Sim;Hong-June Park;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Mar 2017, volume: 64, issue:3, pages: 249 - 253
Publisher: IEEE
 
» A Physics-Based (Verilog-A) Compact Model for DC, Quasi-Static Transient, Small-Signal, and Noise Analysis of MOSFET-Based pH Sensors
Abstract:
High-resolution pH measurement is important for biomedical, food, pharmaceutical industries as well as agricultural/environmental monitoring. Among the pH-meters, FET sensors (pH-FETs) offer several advantages, such as, higher sensitivity, lower cost, and smaller size. In this paper, we develop a physics-based (Verilog-A) compact model to simulate dc, quasi-static transient, small-signal, and noise performance of pH-FET sensors. The Verilog-A implementation would allow pH-FET integration with complex signal processing circuits, and prediction of the integrated performance. The model predicts that FET thermal noise dominates in subthreshold, while FET flicker noise dominates above threshold. The minimum pH resolution is dictated by an interplay of FET and electrolyte noise sources, which are in turn functions of transistor geometry and operating condition. For a given technology node, if the sensor is designed to operate in subthreshold regime, pH-FET with shorter but wider channel has better pH resolution. In contrast, for sensor designed to operate in the inversion regime, longer and wider channel is preferred. Finally, we demonstrate the utility of the Verilog-A implementation by circuit simulation of a low-power sensor interface.
Autors: Piyush Dak;Weeseong Seo;Byunghoo Jung;Muhammad A. Alam;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1285 - 1293
Publisher: IEEE
 
» A Pipeline Replica Bitline Technique for Suppressing Timing Variation of SRAM Sense Amplifiers in a 28-nm CMOS Process
Abstract:
With advances in semiconductor technology, the threshold voltage variation has worsened, which has a great impact on the speed and stability of static random access memory (SRAM). This paper proposes a pipeline replica bitline (RBL) delay technique designed to reduce the timing variation of SRAM sense amplifiers. This design takes full advantage of all cells in the RBL as replica cells (RCs). A tunable pipeline structure is applied to control the discharge of groups of RCs. The structure is designed based on theoretical analysis and fabricated using an SMIC 28-nm CMOS process. The measurement results show that the delay variation can be reduced by approximately 43% and 32% compared with the conventional RBL and multistage RBL, respectively. Furthermore, with slight tuning of the normal 28-nm foundry process, four wafers were obtained under extreme conditions to comprehensively test the proposed technique. The results show that the proposed technique is more stable than other techniques in any extreme condition.
Autors: Zhiting Lin;Xiulong Wu;Zhi Li;Lijun Guan;Chunyu Peng;Changyong Liu;Junning Chen;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Mar 2017, volume: 52, issue:3, pages: 669 - 677
Publisher: IEEE
 
» A Planar Broadband Antenna for the E-Band Gigabyte Wireless Communication
Abstract:
A planar broadband antenna with a center frequency of 81.75 GHz is proposed in this communication, which is composed by an open-ended pentagonal slot etched on the broad surface of a substrate-integrated waveguide (SIW) and a short circuited metallic via inserted inside the ring slot. The broadband SIW 180° phase-shifter and the SIW power-divider are deployed in the design to implement the beam-forming network. As a demonstration, a array is designed on a 0.5 mm thick Rogers5880 substrate, and fabricated by using the low-cost printed circuit board process. Experiments are carried out to verify the design, which show that the measured antenna has a 10 dB return loss bandwidth from 77 to 86. 5 GHz, that is, the fractional bandwidth of 11.6%. The proposed antenna is a promising candidate for the E-band high-speed wireless communication system.
Autors: Zhang-Cheng Hao;Muxin He;Kuikui Fan;Guoqing Luo;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Mar 2017, volume: 65, issue:3, pages: 1369 - 1373
Publisher: IEEE
 
» A Primer on 3GPP Narrowband Internet of Things
Abstract:
Narrowband Internet of Things (NB-IoT) is a new cellular technology introduced in 3GPP Release 13 for providing wide-area coverage for IoT. This article provides an overview of the air interface of NB-IoT. We describe how NB-IoT addresses key IoT requirements such as deployment flexibility, low device complexity, long battery lifetime, support of massive numbers of devices in a cell, and significant coverage extension beyond existing cellular technologies. We also share the various design rationales during the standardization of NB-IoT in Release 13 and point out several open areas for future evolution of NB-IoT.
Autors: Y.-P. Eric Wang;Xingqin Lin;Ansuman Adhikary;Asbjorn Grovlen;Yutao Sui;Yufei Blankenship;Johan Bergman;Hazhir S. Razaghi;
Appeared in: IEEE Communications Magazine
Publication date: Mar 2017, volume: 55, issue:3, pages: 117 - 123
Publisher: IEEE
 
» A Proactive Workflow Model for Healthcare Operation and Management
Abstract:
Advances in real-time location systems have enabled us to collect massive amounts of fine-grained semantically rich location traces, which provide unparalleled opportunities for understanding human activities and generating useful knowledge. This, in turn, delivers intelligence for real-time decision making in various fields, such as workflow management. Indeed, it is a new paradigm to model workflows through knowledge discovery in location traces. To that end, in this paper, we provide a focused study of workflow modeling by integrated analysis of indoor location traces in the hospital environment. In particular, we develop a workflow modeling framework that automatically constructs the workflow states and estimates the parameters describing the workflow transition patterns. More specifically, we propose effective and efficient regularizations for modeling the indoor location traces as stochastic processes. First, to improve the interpretability of the workflow states, we use the geography relationship between the indoor rooms to define a prior of the workflow state distribution. This prior encourages each workflow state to be a contiguous region in the building. Second, to further improve the modeling performance, we show how to use the correlation between related types of medical devices to reinforce the parameter estimation for multiple workflow models. In comparison with our preliminary work [11] , we not only develop an integrated workflow modeling framework applicable to general indoor environments, but also improve the modeling accuracy significantly. We reduce the average log-loss by up to 11 percent.
Autors: Chuanren Liu;Hui Xiong;Spiros Papadimitriou;Yong Ge;Keli Xiao;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Mar 2017, volume: 29, issue:3, pages: 586 - 598
Publisher: IEEE
 
» A Probabilistic Approach to Improve the Accuracy of Axle-Based Automatic Vehicle Classifiers
Abstract:
This paper details a simple and novel approach to solve the assignment problem of finding optimum thresholds for axle-based vehicle classifiers. A case study utilizing Oklahoma's axle-based classification stations was conducted in an effort to build, analyze, and verify the proposed solution. An extensive axle-space database with over 20 000 vehicle samples covering all 13 classes of the Federal Highway Administration's Scheme F was constructed. Histograms and Gaussian distribution fitting were individually done per class, per axle spacing, and from data gathered. Optimal class boundary thresholds were computed using the derived distributions, and a new classification algorithm was constructed. Results of field testing concluded that the newly proposed algorithm outperformed the existing one currently installed statewide and used by the other states as well. A significant false detection classification error reduction was achieved at a rate of 43% for class 8, 21% for class 5, 5% for class 6, and a combined reduction of 26% for classes 2 and 3. In addition, a misdetection error reduction of 21% for class 6, 13% for class 5, and a combined reduction of 37% for classes 2 and 3 was noted. A consolidated system error reduction relative to vehicle type was 15% for multiunit trucks of classes 8 to 13, 4% for single-unit trucks of classes 5 to 7, and 57% for passenger vehicles of classes 1 to 4. The process of calibrating the classification scheme was found to be completely transferable, thus could effectively be used to optimize classification algorithms in other states.
Autors: Naim Bitar;Hazem H. Refai;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Mar 2017, volume: 18, issue:3, pages: 537 - 544
Publisher: IEEE
 
» A Probabilistic Approach to Observability of Distribution Networks
Abstract:
This paper presents a novel probabilistic approach to distribution network observability. The observability analysis is an important part of the state estimation process. Traditionally, it determines whether the state of a network can be estimated based on the available set of measurements. This works well in transmission networks, where numerous metering devices are normally available. In distribution networks, however, only a few metering devices are usually installed. Pseudo measurements with large margins of error are often used in the absence of real measurements to perform state estimation. This implies that if a large number of pseudo measurements is used to make a network observable, the estimated state can be significantly different from the actual state even if the network is classified as observable. To overcome this limitation, a new approach to observability is proposed in this paper. The proposed method takes the uncertainty of the state estimation into account, and therefore, assesses the network observability depending on the accuracy of the estimated network state. This paper also demonstrates how a meter placement method based on the proposed observability assessment can be implemented. The presented methods have been tested on a modified 34-bus IEEE test feeder. Results are compared with existing methods.
Autors: Bernd Brinkmann;Michael Negnevitsky;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1169 - 1178
Publisher: IEEE
 
» A Probabilistic Framework for Building Extraction From Airborne Color Image and DSM
Abstract:
This paper proposes a supervised probabilistic framework for building extraction. Multiple features from both images and point clouds can be fused in this framework to achieve global optimal building extraction. Basically, it adopts conditional random fields (CRFs) to discriminatively model the ground scene and its observed data, and formulates building extraction as a pixel-labeling problem. Color, edge, and height explored from both kinds of data are fused into the association potential and interaction potential of CRFs in order to achieve a global optimal labeling. Furthermore, it develops Gaussian mixture model and height range model for color distribution and height distribution, respectively. These models facilitate parameter learning and model specification from training data. Furthermore, it constructs regular interaction potentials such that global optimization can be solved efficiently by a graph cut algorithm. With the proposed framework, buildings can be extracted automatically and efficiently if training data are annotated in advance. As demonstrated by the experiments and their evaluations, the proposed approach outperforms state of the art techniques and allows further improvement by incorporating additional data or features.
Autors: Dengfeng Chai;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Mar 2017, volume: 10, issue:3, pages: 948 - 959
Publisher: IEEE
 
» A Proton Hopping-Guided 3-D Space Charge Model for Quantitative Understanding of Humidity-Dependent Gas Sensing by TiO2 Nanoflower-Based Devices
Abstract:
Low temperature (90 °C) gas sensing performance, with ethanol as a test case, of TiO2 nanoflowers in the presence of humidity, was investigated. It was revealed that the sensor resistance in air and in ethanol was reduced in the presence of humidity. However, such variations in sensor resistance in the humid and in the nonhumid environment are more pronounced for baseline case (in air) than that in target species exposure (in ethanol). Interaction probability of the target species, in the presence of humidity, with the TiO2 nanoflower surface was governed by the proton hopping model. For quantitative understanding of the subsequent electron generation and transport phenomenon, a space charge model, corelating the influence of mutually competing and interdependent factors like oxygen vacancies, adsorbed O species, dissociation of water and ethanol molecules on TiO2 nanoflower surface, has been demonstrated. It was found that decrease in base line resistance (Δ R) gradually becomes saturated with increase in relative humidity level, possibly owing to proton hopping in the physisorbed water layers which hinders the chemisorption of water molecules at the nanoflower surfaces leading toward relatively insignificant change in space charge region.
Autors: Basanta Bhowmik;Partha Bhattacharyya;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Mar 2017, volume: 16, issue:2, pages: 180 - 188
Publisher: IEEE
 
» A Pseudo OFDM With Miniaturized FSK Demodulation Body-Coupled Communication Transceiver for Binaural Hearing Aids in 65 nm CMOS
Abstract:
A power-efficient body-coupled communication pseudo orthogonal frequency-division multiplexing (P-OFDM) transceiver (TRX) is presented for binaural hearing aids (BHAs). Channel measurements are performed for different body postures between human head-to-hand and ear-to-ear to characterize the body channel path loss. The TRX exploits baseband 16-quadrature amplitude modulation OFDM symbols transmitted through a binary frequency-shift keying (FSK) modulation to mitigate the multipath and interference problems, which are the most serious issues in BHA, with bit error rate improvement of 74% compared to FSK. It is also free from the peak-to-average power ratio problem. A power-of-two decomposition constant multiplier is implemented to achieve area-efficient constant multiplications in 64-FFT. The proposed energy- and area-efficient miniaturized direct conversion FSK demodulation receiver is capable of demodulating up to 20 Mbps signals while reducing the area by >50% compared to conventional implementations. The 1 Mbps TRX is implemented in a 65 nm CMOS process with an active area of 2.13 mm while consuming 1.4 mW.
Autors: Wala Saadeh;Muhammad Awais Bin Altaf;Haneen Alsuradi;Jerald Yoo;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Mar 2017, volume: 52, issue:3, pages: 757 - 768
Publisher: IEEE
 
» A Quasi-3-D Scaling Length Model for Trapezoidal FinFET and Its Application to Subthreshold Behavior Analysis
Abstract:
Based on the equivalent channel width and equivalent number of gates, a quasi-3-D scaling length model for the trapezoidal FinFET (TzFinFET) is developed. By accounting for the coupling effects between equivalent double-gate FET and single-gate FET, the scaling length of TzFinFET can be accurately predicted. Besides Fin height, top Fin width, and gate oxide, the scaling length is also sensitive to the inclination angle induced by the process technology. By applying this derived scaling length to the TzFinFET, the subthreshold behavior model including threshold voltage and subthreshold swing can be achieved. Both threshold voltage roll-off and subthreshold swing roll-up can be well controlled by the scaling factor in accordance with the scaling theory. According to the scaling factor, the acceptable minimum channel length that allows the maximum subthreshold degradation can be uniquely determined. The variability of subthreshold characteristics with the process parameter is also taken into account in this paper.
Autors: Hong-Wun Gao;Yeong-Her Wang;Te-Kuang Chiang;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Mar 2017, volume: 16, issue:2, pages: 281 - 289
Publisher: IEEE
 
» A Range Ambiguity Resolution Approach for High-Resolution and Wide-Swath SAR Imaging Using Frequency Diverse Array
Abstract:
In spaceborne synthetic aperture radar (SAR), it is a challenging problem to realize high resolution and wide swath imaging (HRWS) due to the conflict between Doppler and range ambiguities. To mitigate this conflict, a range ambiguity resolution approach for HRWS SAR imaging using frequency diverse array (FDA) is proposed in this paper. The FDA employs a set of slightly different carrier frequencies, each of which is emitted by an individual array element. Frequency diversity introduces wave-path difference among the array elements, thus resulting in the range-angle-dependent property of transmit steering vector. Utilizing the extra degrees-of-freedom in range domain, FDA is capable of distinguishing the range ambiguous echoes in the spatial frequency domain. In our approach, the range ambiguous echoes are compensated by range dependence compensation (RDC) technique in the transmit spatial frequency domain. In the sequel, the range ambiguous echoes are separated by using a series of transmit beamformers as the echoes from different range regions are discriminable. Finally, traditional imaging processing is performed on the reconstructed unambiguous data to achieve HRWS imaging. Simulation results have verified the effectiveness of the proposed approach.
Autors: Chenghao Wang;Jingwei Xu;Guisheng Liao;Xuefei Xu;Yuhong Zhang;
Appeared in: IEEE Journal of Selected Topics in Signal Processing
Publication date: Mar 2017, volume: 11, issue:2, pages: 336 - 346
Publisher: IEEE
 
» A Real-Time En-Route Route Guidance Decision Scheme for Transportation-Based Cyberphysical Systems
Abstract:
In transportation-based cyberphysical systems (TCPS), also known as intelligent transportation systems (ITS), to increase traffic efficiency, a number of dynamic route guidance schemes have been designed to assist drivers in determining optimal routes for their travels. To determine optimal routes, it is critical to effectively predict the traffic condition of roads along the guided routes based on real-time traffic information collected by vehicular networks to mitigate traffic congestion and improve traffic efficiency. In this paper, we propose a Dynamic En-route Decision real-time Route guidance (DEDR) scheme to effectively mitigate road congestion caused by the sudden increase of vehicles and to reduce travel time and fuel consumption. DEDR considers real-time traffic information generation and transmission by vehicular networks. Based on the shared traffic information, DEDR introduces the trust probability to predict traffic conditions and to dynamically, en route, determine alternative optimal routes. DEDR also considers multiple metrics to comprehensively assess traffic conditions so that drivers can determine the optimal route with a preference to these metrics during travel. DEDR considers effects of external factors (bad weather, incidents, etc.) on traffic conditions as well. Through a combination of extensive theoretical analysis and simulation experiments, our data show that DEDR can greatly increase traffic efficiency in terms of time efficiency, balancing efficiency, and fuel efficiency, in comparison with existing schemes.
Autors: Jie Lin;Wei Yu;Xinyu Yang;Qingyu Yang;Xinwen Fu;Wei Zhao;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Mar 2017, volume: 66, issue:3, pages: 2551 - 2566
Publisher: IEEE
 
» A Reappraisal of Optimum Output Matching Conditions in Microwave Power Transistors
Abstract:
This paper presents a novel approach to the identification of output power and efficiency contours in microwave power transistors in compressed regime. The formulation is based on a polynomial representation of the drain–source voltage profile accounting for the knee region. Closed-form equations for the output power and efficiency as function of the fundamental load are demonstrated, enabling the plot of contours on a Smith Chart. From these, a further simplified drawing procedure for approximated contours is also derived, differentiating between two families of output characteristic. The first, with smooth knee, is usually experienced in GaN devices, while the second exhibits a steep knee which can be associated with GaAs devices’ typical behavior. A 5-W GaN HEMT, a 2.5-W GaN HEMT, and a 0.7-W GaAs pHEMT are characterized with load-pull measurements. In all the three cases, the proposed method results in a very accurate contour construction, despite being based on an approximated output current/voltage profile and on a rough estimate of output equivalent capacitance.
Autors: Roberto Quaglia;Daniel J. Shepphard;Steve Cripps;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Mar 2017, volume: 65, issue:3, pages: 838 - 845
Publisher: IEEE
 

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  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    

 
0-C     D-L     M-R     S-Z