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Electrical and Electronics Engineering publications abstract of: 01-2017 sorted by title, page: 4

» Demonstration of Counter-Propagating Raman Pump Placed Near Signal-Channel Wavelengths
Abstract:
As optical-fiber capacity is increased by the use of multiple signal bands such as the combined S+C+L bands, signals in the -band may have to co-exist with Raman pumps operating in nearby wavelength slots. We investigate the impact of placing a counter-propagating Raman pump near a 32-Gbd polarization-division-multiplexed 16-ary quadrature-amplitude-modulated signal.
Autors: A. H. Gnauck;R. M. Jopson;P. J. Winzer;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2017, volume: 29, issue:1, pages: 154 - 157
Publisher: IEEE
 
» Demonstration of Optical FEC Coding Scheme With Convolutional Code Consisting of a Signal Source
Abstract:
In this letter, we experimentally demonstrated an all-optical forward error correction (FEC) coding scheme with the convolutional code using a single signal source to compensate time-dependent noise. The proposed coding scheme was comprised of optical XOR gates, delay lines, and optical wavelength converters, which are based on four-wave mixing in highly non-linear fibers. The temporal waveforms of the optical FEC coding scheme were experimentally achieved for 10 Gb/s return-to-zero differential phase shift keying (RZ-DPSK) signals modulated with , and the obtained idler signals accurately corresponded to the code between any input signals. Under the optimized conditions of operational wavelengths, the proposed scheme theoretically offered 4.0 and 3.5 dB net coding gains for the conditions of BER and BER , respectively, owing to its small power penalties.
Autors: Yohei Aikawa;Hiroyuki Uenohara;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2017, volume: 29, issue:1, pages: 165 - 168
Publisher: IEEE
 
» Deriving Maximum Light Use Efficiency From Crop Growth Model and Satellite Data to Improve Crop Biomass Estimation
Abstract:
Maximum light use efficiency () is an important parameter in biomass estimation models (e.g., the Production Efficiency Models (PEM)) based on remote sensing data; however, it is usually treated as a constant for a specific plant species, leading to large errors in vegetation productivity estimation. This study evaluates the feasibility of deriving spatially variable crop from satellite remote sensing data. at the plot level was retrieved first by assimilating field measured green leaf area index and biomass into a crop model (the Simple Algorithm for Yield estimate model), and was then correlated with a few Landsat-8 vegetation indices (VIs) to develop regression models. was then mapped using the best regression model from a VI. The influence factors on variability were also assessed. Contrary to a fixed , our results suggest that is affected by environmental stresses, such as leaf nitrogen deficiency. The strong correlation between the plot-level and VIs, particularly the two-band enhanced vegetation index for winter wheat (Triticum aestivum) and the green chlorophyll index for maize (Zea mays) at the milk stage, provided a potential to deri- e from remote sensing observations. To evaluate the quality of derived from remote sensing data, biomass of winter wheat and maize was compared with that estimated using a PEM model with a constant and the derived variable . Significant improvements in biomass estimation accuracy were achieved (by about 15.0% for the normalized root-mean-square error) using the derived variable . This study offers a new way to derive for a specific PEM and to improve the accuracy of biomass estimation using remote sensing.
Autors: Taifeng Dong;Jiangui Liu;Budong Qian;Qi Jing;Holly Croft;Jingming Chen;Jinfei Wang;Ted Huffman;Jiali Shang;Pengfei Chen;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Jan 2017, volume: 10, issue:1, pages: 104 - 117
Publisher: IEEE
 
» Description of an Electrodynamic Self-Bearing Permanent Magnet Machine
Abstract:
This paper aims to give a description of a passively levitated self-bearing permanent magnet motor principle. The windings of a permanent magnet motor are connected in such a way that they are also coupled to the 1 harmonics due to a rotor off-centering. They allow for eddy currents to flow inside a short-circuit path when the rotor is out-centered, and in consequence to generate radial force according to the principle of radial heteropolar electrodynamic bearings. The general principles are described, and a 2-D-FE time-dependent model illustrates those principles on two application cases. The theoretical feasibility of this passively levitated permanent magnet motor is shown on a slotless application case.
Autors: Virginie Kluyskens;Corentin Dumont;Bruno Dehez;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jan 2017, volume: 53, issue:1, pages: 1 - 9
Publisher: IEEE
 
» Design and Modeling of a Six-Degree-of-Freedom Magnetically Levitated Positioner Using Square Coils and 1-D Halbach Arrays
Abstract:
This paper presents a novel design of six-degree-of-freedom (6-DOF) magnetically levitated (maglev) positioner, where its translator and stator are implemented by four groups of 1-D Halbach permanent-magnet (PM) arrays and a set of square coils, respectively. By controlling the eight-phase square coil array underneath the Halbach PM arrays, the translator can achieve 6-DOF motion. The merits of the proposed design are mainly threefold. First, this design is potential to deliver unlimited-stroke planar motion with high power efficiency if additional coil switching system is equipped. Second, multiple translators are allowed to operate simultaneously above the same square coil stator. Third, the proposed maglev system is less complex in regard to the commutation law and the phase number of coils. Furthermore, in this paper, an analytical modeling approach is established to accurately predict the Lorentz force generated by the square coil with the 1-D Halbach PM array by considering the corner region, and the proposed modeling approach can be extended easily to apply on other coil designs such as the circular coil, etc. The proposed force model is evaluated experimentally, and the results show that the approach is accurate in both single- and multiple-coil cases. Finally, a prototype of the proposed maglev positioner is fabricated to demonstrate its 6-DOF motion ability. Experimental results show that the root-mean-square error of the implemented maglev prototype is around 50 nm in planar motion, and its velocity can achieve up to 100 mm/s.
Autors: Haiyue Zhu;Tat Joo Teo;Chee Khiang Pang;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jan 2017, volume: 64, issue:1, pages: 440 - 450
Publisher: IEEE
 
» Design and Simulation of Low-Power Logic Gates Based on Nanoscale Side-Contacted FED
Abstract:
A new nanoscale device has been already introduced as a side-contacted field effect diode (S-FED), which is composed of a diode and planar SOI-MOSFET. In this paper, S-FED is optimized in terms of work function, with due attention to the design of logic gates, such as NOT, NAND, NOR, and XOR. Results demonstrate that optimum work function is 4.7 eV in which the highest value of can be achieved. Mixed-mode simulations are used to determine the performance of the proposed logic gates. Also, the proof regarding the mitigation of the total power consumption up to 56% is presented so that not gate based on S-FED improves power delay product by about 30%, compared with the CMOS-based version. A similar fabrication process with the CMOS technology could be asserted as the considerable advantage to pave the way of feasibly realizing the new generation of S-FED-based logic gates.
Autors: Behnam Jafari Touchaei;Negin Manavizadeh;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2017, volume: 64, issue:1, pages: 306 - 311
Publisher: IEEE
 
» Design and Validation of a Novel MR-Compatible Sensor for Respiratory Motion Modeling and Correction
Abstract:
Goal: A novel magnetic resonance (MR) compatible accelerometer for respiratory motion sensing (MARMOT) is developed as a surrogate of the vendors’ pneumatic belts. We aim to model and correct respiratory motion for free-breathing thoracic-abdominal MR imaging and to simplify patient installation. Methods: MR compatibility of MARMOT sensors was assessed in phantoms and its motion modeling/correction efficacy was demonstrated on 21 subjects at 3 T. Respiration was modeled and predicted from MARMOT sensors and pneumatic belts, based on real-time images and a regression method. The sensor accuracy was validated by comparing motion errors in the liver/kidney. Sensor data were also exploited as inputs for motion-compensated reconstruction of free-breathing cardiac cine MR images. Multiple and single sensor placement strategies were compared. Results: The new sensor is compatible with the MR environment. The average motion modeling and prediction errors with MARMOT sensors and with pneumatic belts were comparable (liver and kidney) and were below 2 mm with all tested configurations (belts, multiple/single MARMOT sensor). Motion corrected cardiac cine images were of improved image quality, as assessed by an entropy metric (p  <  10−6), with all tested configurations. Expert readings revealed multiple MARMOT sensors were the best (p  <  0.03) and the single MARMOT sensor was similar to the belts (nonsignificant in two of the three readers). Conclusion: The proposed sensor can model and predict respiratory motion with sufficient accuracy to allow free-breathing MR imaging strategy. Significance: It provides an alternative sensor solution for the respiratory motion prob- em during MR imaging and may improve the convenience of patient setup.
Autors: Bailiang Chen;Nicolas Weber;Freddy Odille;Claire Large-Dessale;Antoine Delmas;Laurent Bonnemains;Jacques Felblinger;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jan 2017, volume: 64, issue:1, pages: 123 - 133
Publisher: IEEE
 
» Design Approach for Multiband Horn Antennas Mixing Multimode and Hybrid Mode Operation
Abstract:
The design of a quad-band (18, 28, 38, and 48 GHz) feed horn is presented. Corrugations are used for a good polarization purity at the higher frequencies. At the lower frequency, they act as a smooth wall and the horn profile is tuned to achieve a high aperture efficiency.
Autors: J.-P. Adam;M. Romier;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2017, volume: 65, issue:1, pages: 358 - 364
Publisher: IEEE
 
» Design Consideration on the Square-Wave Voltage Injection for Sensorless Drive of Interior Permanent-Magnet Machines
Abstract:
Although it is widely known that the saliency-based position-sensorless drive is able to achieve the closed-loop control at zero and low speed, there is little literature addressing the consideration on the selection of injection voltage frequency. This paper evaluates the square-wave injection voltage at different frequencies for the design of an interior permanent-magnet (PM) machine sensorless drive. It is shown that more flux saturation on high-frequency (HF) d-axis inductance occurs than the saturation on q-axis inductance due to the magnetic relaxation. The HF saliency ratio is increased by increasing the injection frequency. The performance of a saliency-based sensorless drive can be enhanced by properly designing the frequency of injection voltage. This paper also includes the experimental comparison between closed-loop encoder-based and closed-loop saliency-based sensorless operation of an interior PM machine drive.
Autors: Shih-Chin Yang;Sheng-Ming Yang;Jing- Hui Hu;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jan 2017, volume: 64, issue:1, pages: 159 - 168
Publisher: IEEE
 
» Design Fiction: Anticipating Adoption
Abstract:
This tutorial highlights the potential of design fiction with Game of Drones, a fictional user trial of an imagined Drone Enforcement System. The authors explore a potential future use of drones for civic enforcement activities and advance a program for developing design fiction as a research method. This method provides a means for exploring the societal, technological, and political nuances of possible futures so researchers can better consider possible adoption pathways for emerging technologies. This tutorial is part of a special issue on drones.
Autors: Paul Coulton;Joseph Lindley;
Appeared in: IEEE Pervasive Computing
Publication date: Jan 2017, volume: 16, issue:1, pages: 43 - 47
Publisher: IEEE
 
» Design of a Multilayer Graphene-Based Ultrawideband Terahertz Absorber
Abstract:
In this paper, an step by step efficient design procedure for designing a multilayer absorber using graphene thin films is presented. The absorber design is based on scattering parameters of plasmonic waves propagating on the surface of graphene layers. We have provided appropriate interpretations for designing different features of the absorber including graphene pattern and substrate material. We have also presented a multilayer graphene-based ultrawideband terahertz absorber that is designed using the proposed method. Presented absorber has perfect absorption over 2.7 THz and its central frequency is about 3 THz, which is an acceptable fractional bandwidth ultrawideband absorbers.
Autors: Alireza Fardoost;Fatemeh Ghaedi Vanani;As’ad Amirhosseini;Reza Safian;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jan 2017, volume: 16, issue:1, pages: 68 - 74
Publisher: IEEE
 
» Design of a Wideband System for Measuring Dielectric Properties
Abstract:
A dielectric object placed in the near-field region of an antenna produces a scattered field, which alters the input impedance of the antenna. This property can be used to measure the electric parameters of dielectric materials. A wideband system for measuring the dielectric properties in the frequency range from 1.1 to 3.5 GHz is designed and prototyped. The system consists of a wideband directional antenna, a wideband radio frequency circuit, and a data processing unit and has been tested by using different dielectric samples across the frequency band, and good measurement results have been obtained.
Autors: Xiangzhen Wang;Wen Geyi;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2017, volume: 66, issue:1, pages: 69 - 76
Publisher: IEEE
 
» Design of an Adaptive Multiresolution $M$ -Ary DCSK System
Abstract:
Multiresolution -ary differential chaos shift keying (MR--DCSK) system enables unequal-priority transmission via exploiting non-uniformly spaced phase constellations. In this letter, an adaptive MR--DCSK system is proposed by using a new constellation parameter design. Aiming at maximizing the spectral efficiency, the constellation parameter is carefully selected based on signal-to-noise ratio, and then is further optimized by a new search algorithm. Both the analytical and simulation results show that the proposed adaptive MR--DCSK system not only can enhance the spectral efficiency as compared with the adaptive -DCSK system, but can satisfy different bit-error-rate requirements for different bits within a symbol as well.
Autors: Guofa Cai;Yi Fang;Guojun Han;
Appeared in: IEEE Communications Letters
Publication date: Jan 2017, volume: 21, issue:1, pages: 60 - 63
Publisher: IEEE
 
» Design of Compact HTS Dual-Band Bandpass Filters Using Dual-Function Feeding Structure With Wide Stop-Band Response
Abstract:
We have developed a compact high-temperature superconducting four-pole dual-band bandpass filter (DBPF) using a dual-function feeding structure with a wide stop-band response. Use of shorted stub-loaded hairpin resonators enabled its achievement. The coupling coefficients are flexibly controlled by using a pair of H-shaped coupling elements between the resonators. A dual-function feeding structure is newly developed for flexibly adjusting the external coupling for the two bands. A tapped-line coupling is used to adjust the external coupling for the first band, and a coupled-line coupling is used to adjust the external coupling for the second one. The DBPF was designed to operate at 0.8 GHz with a 16-MHz (2%) bandwidth for the first band and at 2.0 GHz with a 40-MHz (2%) bandwidth for the second band. A compact (30 mm × 28.25 mm) filter was fabricated using YBa2Cu3 Oy thin film on a CeO2-buffered Al2O3 substrate. The measured results agree well with the simulated ones.
Autors: Naoto Sekiya;
Appeared in: IEEE Transactions on Applied Superconductivity
Publication date: Jan 2017, volume: 27, issue:1, pages: 1 - 4
Publisher: IEEE
 
» Design of Financial Incentive ProgramsPub _newline to Promote Net Zero Energy Buildings
Abstract:
Promoting net zero energy buildings (NZEB) is among the key carbon emissions reduction approaches widely adopted by policymakers in recent years in the U.S. and the EU countries (see work of Marszal ). Due to the relatively higher cost of electricity generation from renewable energy (RE), federal, state, and local governments offer various financial incentive programs to promote NZEB. This paper presents a model-based framework for the policymakers to design suitable incentive programs. The model is a mixed integer program (MIP) that is particularized for wind and solar energy sources. The MIP model finds an optimal design for a NZEB. The optimal design and the cost of NZEB is then used to design incentive programs. The incentive programs considered includes loans, production tax credit, and net metering, among others. A time-of-day pricing is assumed to be in effect. The model is implemented on commercial buildings in Tampa, Florida, U.S.A. For a given region, the framework provides policymakers two reports, 1) a set of optimal portfolios of incentives for different classes of commercial buildings (based on credit rating, expected return on investment (ROI), and building type), 2) for a specified portfolio of incentives, determines which classes of commercial buildings will be willing to invest in RE.
Autors: Alireza Ghalebani;Tapas K. Das;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jan 2017, volume: 32, issue:1, pages: 75 - 84
Publisher: IEEE
 
» Design of Fixed-Frequency Pulsewidth-Modulation-Based Sliding-Mode Controllers for the Quadratic Boost Converter
Abstract:
The steady-state regulation error in power converters that use the pulsewidth-modulation (PWM)-based sliding-mode (SM) controllers can be alleviated via the use of a double-integral term of the state variables in the sliding surface. However, this not only increases the order of the controller but may also require more variables like two currents in feedback. Ideally, the controller should be of a lower order to reduce the cost and for ease of implementation. The main objective of this brief is to design a fixed-frequency PWM-based SM controller for the quadratic boost converter using a reduced number of state variables. The SM controller used in this brief requires only one current for its implementation while enjoying the advantages offered by both fixed-frequency and double-integral approaches. Apart from this, two SM controllers using the input and output inductor currents of the converter are separately designed to find the most suitable inductor current for the controller design. Such study is especially required for the higher order converters wherein more than one inductor currents are available for feedback purposes. It is shown that the controller using the input inductor current is preferred over the controller using the output inductor current. Some simulation and experimental results are also provided to validate the theoretical conclusions.
Autors: Satyajit Hemant Chincholkar;Chok-You Chan;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jan 2017, volume: 64, issue:1, pages: 51 - 55
Publisher: IEEE
 
» Design of High-Performance Filtering Balun Based on TE01δ-Mode Dielectric Resonator
Abstract:
This paper presents a fusion design approach of high-performance filtering balun based on the ring-shaped dielectric resonator (DR) for the first time. According to the electromagnetic (EM) field properties of the TE01δ mode of the DR cavity, it can be differentially driven or extracted by reasonably placing the orientations of the feeding probes, which answers for the realization of unbalanced-to-balanced conversion. As a result, the coupling between the resonators can refer to the traditional single-ended design, regardless of the feeding scheme. Based on this, a second-order DR filtering balun is designed by converting a four-port balanced filter to a three-port device. Within the passband, the excellent performance of amplitude balance and phase difference at the balun outputs can be achieved. To improve the stopband rejection by suppressing the spurious responses of the DR cavity, a third-order filtering balun using the hybrid DR and coaxial resonator is designed. It is not rigorously symmetrical, which is different from the traditional designs. The simulated and measured results with good accordance showcase good filter and balun functions at the same time.
Autors: Jian-Xin Chen;Yang Zhan;Wei Qin;Zhi-Hua Bao;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jan 2017, volume: 64, issue:1, pages: 451 - 458
Publisher: IEEE
 
» Deterministic Networked Control of Discrete Event Systems With Nondeterministic Communication Delays
Abstract:
We continue to investigate the impacts of communication delays on networked control of discrete event systems (DES). Our previous results show that nondeterministic communication delays result in nondeterminism in the languages generated by the controlled system, which makes the networked control problems more complex. In this paper we investigate the language nondeterminism. We define delay observability and delay controllability. If the language to be synthesized is delay observable and delay controllable, we can synthesize a networked supervisor to control the DES such that the language generated by the controlled system is deterministic, that is, we can synthesize a “deterministic” state-estimate-based networked supervisor. We derive algorithms to check delay controllability and delay observability. If the language to be synthesized is not delay observable and/or delay controllable, we can find its infimal delay controllable and delay observable superlanguage and maximal delay controllable and delay observable sublanguages. We develop algorithms to find these superlanguages and sublanguages. All the algorithms proposed in the paper are of polynomial computational complexity.
Autors: Shaolong Shu;Feng Lin;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jan 2017, volume: 62, issue:1, pages: 190 - 205
Publisher: IEEE
 
» Deterministic Pilot Design for Sparse Channel Estimation in MISO/Multi-User OFDM Systems
Abstract:
We study the pilot design problem for sparse channel estimation in OFDM systems where multiple channels are estimated at a single antenna receiver. Such design is applicable to downlink of massive-MIMO systems and also to scenarios where multiple users transmit to a base station at the same carrier frequency. In our design, we deviate from the conventional orthogonal pilot arrangements by assigning the same pilot subcarriers to all transmitters. In the proposed setting, the achieved improvement in spectral efficiency (by reducing pilot overhead) may come at the expense of a more challenging channel estimation block at the receiver. To address this challenge and distinguish between different signals that are arriving at the receiver at the same subcarrier, we propose to select pilot subcarriers through minimizing the coherence of the associated Fourier submatrix, as well as properly assigning different pilot values (complex numbers) to each individual transmitter. We demonstrate that if the channels are sparse enough in time domain, there are simple sparse recovery techniques to simultaneously estimate all the channels, although all transmitters share the same pilot subcarriers. Simulation results demonstrate that the proposed design outperforms existing methods in terms of both mean-square channel estimation error and bit error rate.
Autors: Roozbeh Mohammadian;Arash Amini;Babak Hossein Khalaj;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2017, volume: 16, issue:1, pages: 129 - 140
Publisher: IEEE
 
» Development and Dynamic Characterization of a Mixed Mode Magnetorheological Elastomer Isolator
Abstract:
Magnetorheological elastomers (MREs) are a kind of smart material, whose mechanical properties are controllable with applied magnetic field. Moreover, there is a greater magnetorheological effect for MREs at small strain amplitude, which has attracted more attention in the field of microvibration control. In this paper, an MRE isolator with shear-compression mixed mode was developed to suppress the high-frequency and microamplitude vibration of a precision-fabrication platform. To evaluate and characterize the dynamic behavior of the MRE isolator, experiments were conducted under harmonic load and different magnetic fields, respectively. Experiments showed that the resonance frequency of the MRE isolation system shifted from 45.82 (0 A) to 82.55 Hz (1.5 A). Meanwhile, the relative change in equivalent stiffness and damping was 175% and 216%, respectively, and the relative change in isolator force was 190% from 0 to 1.5 A. The proposed mixed mode MRE isolator effectively isolated vibration at high frequency for microamplitude.
Autors: Jie Fu;Peidong Li;Guanyao Liao;Junjie Lai;Miao Yu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jan 2017, volume: 53, issue:1, pages: 1 - 4
Publisher: IEEE
 
» Development and Experimental Validation of a Non-Linear, All-Elastomer In-Plane Capacitive Pressure Sensor Model
Abstract:
A large deformation mechanics model is applied to predict capacitance changes in an all-elastomer capacitive tactile sensor, and the predictive model is experimentally validated. The compressive model predicts a non-linear relationship between the contact normal force and resulting capacitance change due to changes in electrode gap and electrode layer thickness. Broad parametric studies demonstrate that higher sensitivities can be achieved with lower modulus materials and smaller electrode gaps. Sensors are fabricated using a reusable silicon mold and experimental results are compared to predictions from the capacitance model. Capacitance-force model predictions yielded by the calibrated capacitance analytical model are shown to be in remarkable agreement with experimental measurements. A fringe effects term included in the capacitance model highlights the limitations of the parallel plate model especially for sensors with large electrode layer gaps.
Autors: Kourosh M. Kalayeh;Alexi Charalambides;Sarah Bergbreiter;Panos G. Charalambides;
Appeared in: IEEE Sensors Journal
Publication date: Jan 2017, volume: 17, issue:2, pages: 274 - 285
Publisher: IEEE
 
» Device-to-Device Communication Underlaying a Finite Cellular Network Region
Abstract:
Underlay in-band device-to-device (D2D) communication can improve the spectrum efficiency of cellular networks. However, the coexistence of D2D and cellular users causes inter-cell and intra-cell interference. The former can be effectively managed through inter-cell interference coordination and, therefore, is not considered in this paper. Instead, we focus on the intra-cell interference and propose a D2D mode selection scheme to manage it inside a finite cellular network region. The potential D2D users are controlled by the base station (BS) to operate in D2D mode based on the average interference generated to the BS. Using stochastic geometry, we study the outage probability experienced at the BS and a D2D receiver, and spectrum reuse ratio, which quantifies the average fraction of successfully transmitting D2D users. The analysis shows that the outage probability at the D2D receiver varies for different locations. In addition, without impairing the performance at the BS, if the path-loss exponent on the cellular link is slightly lower than that on the D2D link, the spectrum reuse ratio can have negligible decrease, while the D2D users’ average number of successful transmissions increases with increasing D2D node density. This indicates that an increasing level of D2D communication can be beneficial in future networks.
Autors: Jing Guo;Salman Durrani;Xiangyun Zhou;Halim Yanikomeroglu;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2017, volume: 16, issue:1, pages: 332 - 347
Publisher: IEEE
 
» Diamond Schottky Barrier Diodes With NO2 Exposed Surface and RF-DC Conversion Toward High Power Rectenna
Abstract:
A novel diamond Schottky barrier diode (SBD) with H-terminated surface exposed to NO2 gas is fabricated toward high power rectifying antenna (rectenna). The double NO2 exposures are introduced to provide high concentration of 2-D hole gas at the diamond surface. Experimentally, our SBDs have shown to give good rectifier properties with the high current density of 24 A/cm at a forward voltage of −2 V. A dual diode rectifier circuit using two diamond SBDs was designed with diode model constructed from experimental – curves. Values of circuit components such as dc block capacitance and load resistance were selected to achieve larger output voltage. Experimentally RF to dc conversion is demonstrated, where RF input voltage with 10 MHz and the amplitude of 9 V was converted into a dc output voltage as large as 4.2 V.
Autors: Toshiyuki Oishi;Naoto Kawano;Satoshi Masuya;Makoto Kasu;
Appeared in: IEEE Electron Device Letters
Publication date: Jan 2017, volume: 38, issue:1, pages: 87 - 90
Publisher: IEEE
 
» Dielectric Response of Corn Leaves to Water Stress
Abstract:
Radar backscatter from a vegetated surface is sensitive to direct backscatter from the canopy and two-way attenuation of the signal as it travels through the canopy. Both mechanisms are affected by the dielectric properties of the individual elements of the canopy, which are primarily a function of water content. Leaf water content of corn can change considerably during the day and in response to water stress, and model simulations suggested that this significantly affects radar backscatter. Understanding the influence of water stress on leaf dielectric properties will give insight into how the plant water status changes in response to water stress and how radar can be used to detect vegetation water stress. We used a microstrip line resonator to monitor the changes in its resonant frequency at corn leaves, due to variations in dielectric properties. This letter presents the in vivo resonant frequency measurements during field experiments with and without water stress, to understand the dielectric response due to stress. The resonant frequency of the leaf around the main leaf of the stressed plant showed increasing diurnal differences. The dielectric response of the unstressed plant remained stable. This letter shows the clear statistically significant effect of water stress on variations in resonant frequency at individual leaves.
Autors: Tim Van Emmerik;Susan C. Steele-Dunne;Jasmeet Judge;Nick Van De Giesen;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jan 2017, volume: 14, issue:1, pages: 8 - 12
Publisher: IEEE
 
» Differential Chaos Shift Keying: A Robust Modulation Scheme for Power-Line Communications
Abstract:
The past few years have witnessed a tremendous development in power-line communications (PLCs) for the realization of smart grids. Since power lines were not originally intended for conveying high-frequency signals, any communication over these lines would be exposed to severe adversarial factors, such as interference, impulsive, and phase noise. This elucidates the importance of employing robust modulation techniques and motivates research in this direction. Indeed, the aim of this brief is to propose a differential chaos shift keying (DCSK) modulation scheme as a potential candidate for smart grid communication networks. This DCSK class of noncoherent modulation is very robust against linear and nonlinear channel distortions. More importantly, the demodulation process can be carried out without any channel estimator at the receiver side. In this work, we analyze the bit error rate performance of DCSK over multipath PLC channels in which phase, background, and impulsive noise are present. A simulator is developed to verify the performance of the proposed DCSK against direct sequence code division multiple access and direct sequence differential phase shift keying. The results presented in this work prove the advantages of this low-cost noncoherent modulation technique for PLC systems over its rivals.
Autors: Georges Kaddoum;Navid Tadayon;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jan 2017, volume: 64, issue:1, pages: 31 - 35
Publisher: IEEE
 
» Differential Lines for Common-Mode Suppression Based in Hybrid Microstrip/CPW Technology
Abstract:
A symmetrical pair of differential microstrip lines implemented in hybrid microstrip/coplanar waveguide (CPW) technology is proposed. Transmission-line models are used to analyze differential- and common-mode responses, allowing efficient design with minimal optimization effort. The structure behaves as a conventional transmission line pair under differential-mode excitation, whereas asymmetrical coupled transmission line theory has to be applied to characterize common-mode operation. The common mode is strongly suppressed thanks to the introduction of a controllable transmission zero. A two-stage version of the structure is used to increase the common-mode rejection bandwidth. All the electrical parameters of the transmission lines have been obtained using an in-house fast quasi-TEM code. The good agreement between transmission-line models, full-wave simulations and measurements confirms the benefits of the structure and the design procedure.
Autors: Jesús Martel;Armando Fernández-Prieto;Aintzane Lujambio;Francisco Medina;Francisco Mesa;Rafael R. Boix;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jan 2017, volume: 27, issue:1, pages: 13 - 15
Publisher: IEEE
 
» Differential Orthogonal Space-Time Block Coding Modulation for Time-Variant Underwater Acoustic Channels
Abstract:
Reliable underwater acoustic (UWA) communications are challenging since the channels are well known to be doubly selective in both time and frequency domains. The doubly-selective fading UWA channels, however, also provide double diversity gains. In addition, multiple transducers and/or hydrophones are often deployed, providing space diversity to combat channel fading. To exploit all these diversities, a differential multiple-input–multiple-output (MIMO) scheme for doubly-selective fading channels is presented in this paper. The proposed differential orthogonal space-time block coding (DOSTBC) approach adopts the basis expansion model (BEM) to capture the channel variation in time domain. Both analytical and simulated results show that the proposed BEM–DOSTBC approach is reliable by collecting 3-D diversity: space, multipath, and Doppler. The proposed approach was tested during the RACE08 sea experiment and its reliability was confirmed by the experiment results.
Autors: Fengzhong Qu;Zhenduo Wang;Liuqing Yang;
Appeared in: IEEE Journal of Oceanic Engineering
Publication date: Jan 2017, volume: 42, issue:1, pages: 188 - 198
Publisher: IEEE
 
» Differentially Private Distributed Constrained Optimization
Abstract:
Many resource allocation problems can be formulated as an optimization problem whose constraints contain sensitive information about participating users. This paper concerns a class of resource allocation problems whose objective function depends on the aggregate allocation (i.e., the sum of individual allocations); in particular, we investigate distributed algorithmic solutions that preserve the privacy of participating users. Without privacy considerations, existing distributed algorithms normally consist of a central entity computing and broadcasting certain public coordination signals to participating users. However, the coordination signals often depend on user information, so that an adversary who has access to the coordination signals can potentially decode information on individual users and put user privacy at risk. We present a distributed optimization algorithm that preserves differential privacy, which is a strong notion that guarantees user privacy regardless of any auxiliary information an adversary may have. The algorithm achieves privacy by perturbing the public signals with additive noise, whose magnitude is determined by the sensitivity of the projection operation onto user-specified constraints. By viewing the differentially private algorithm as an implementation of stochastic gradient descent, we are able to derive a bound for the suboptimality of the algorithm. We illustrate the implementation of our algorithm via a case study of electric vehicle charging. Specifically, we derive the sensitivity and present numerical simulations for the algorithm. Through numerical simulations, we are able to investigate various aspects of the algorithm when being used in practice, including the choice of step size, number of iterations, and the trade-off between privacy level and suboptimality.
Autors: Shuo Han;Ufuk Topcu;George J. Pappas;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jan 2017, volume: 62, issue:1, pages: 50 - 64
Publisher: IEEE
 
» Differentiating Tree and Shrub LAI in a Mixed Forest With ICESat/GLAS Spaceborne LiDAR
Abstract:
Leaf area index (LAI) is an important descriptor of many biological and physical processes of vegetation. However, the challenges associated with differentiating tree and shrub LAI (tsLAI) have hindered research in mixed forests. Being the first spaceborne LiDAR system, geoscience laser altimeter system (GLAS) has demonstrated its advantage in collecting extensive forest structure information. In this study, we aimed to estimate tsLAI in a mixed forest with GLAS. The refined Levenberg–Marquardt algorithm for Gaussian decomposition was implemented to decompose GLAS data into ground and multiple vegetation signals, within which it is hypothesized that each vegetation signal corresponds to a particular height layer. Subsequently, the height of each layer was extracted through the decomposed GLAS signals, and a height threshold method to distinguish trees from shrubs was developed. Then, a tsLAI-specific ratio defined as ground-to-total energy return of the GLAS signal was calculated, and tsLAI was predicted by a linear regression model established from field measurements and the ratio. Finally, a study site in Ejina, China, where the dominant species are Populus euphratica (tree) and Tamarix ramosissima (shrub) was used to calibrate and validate the methods. Compared with the field measurement LAI, GLAS-predicted LAI presented a high agreement in which R2 , RMSE, and %RMSE of trees were determined to be 0.797, 0.087, and 19.176, respectively. In contrast, R2 , RMSE, and %RMSE of shrubs were found to be 0.676, 0.081, and 21.825, respectively. Overall, our study provided a feasible and effective approach for estimating tsLAI with GLAS over a flat region.
Autors: Jinyan Tian;Le Wang;Xiaojuan Li;Chen Shi;Huili Gong;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Jan 2017, volume: 10, issue:1, pages: 87 - 94
Publisher: IEEE
 
» Diffuse Vacuum Arc on the Nonthermionic Lead Cathode
Abstract:
Experimental study of the diffuse vacuum arc discharge on the nonthermionic lead cathode is presented. At the working cathode temperatures of 1.2–1.6-kK current–voltage characteristic of the discharge, cathode heat operation regime and its erosion rate were measured. Using probe methods, electron temperature (0.3–1.2 eV) and heavy particles (atoms and ions) mean charge (0.17–0.28 e) were determined in after-anode plasma. Evaluated current densities on the cathode are in agreement with a hypothesis on the ion mechanism of charge transfer on its surface. Parameters of the obtained discharge have been compared with the characteristics of the earlier investigated diffuse vacuum arcs on nonthermionic chromium and on thermionic gadolinium cathodes. The obtained data might be useful when creating plasma sources for verifying the plasma separation method of the spent nuclear fuel using the nonradioactive substances.
Autors: Ravil Kh. Amirov;Andrey V. Gavrikov;Gennadii D. Liziakin;Vladimir P. Polistchook Polishchuk;Igor S. Samoylov;Valentin P. Smirnov;Ravil A. Usmanov;Nazar A. Vorona;Ivan M. Yartsev;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jan 2017, volume: 45, issue:1, pages: 140 - 147
Publisher: IEEE
 
» Digital Noninverting-Buck–Boost Converter With Enhanced Duty-Cycle-Overlap Control
Abstract:
The nonideal effects of the comparator and dead time in a synchronous controlled dc-dc converter adversely affect the stability of a four-switch noninverting-buck–boost (NIBB) converter. The pulse-skipping phenomenon occurs in the mode-transition region near the boundary between the step-down and step-up regions, and this phenomenon leads to an unstable output voltage and an unpredictable output voltage ripple. However, these two results may damage the entire power system and application system. This brief proposes an enhanced duty-cycle-overlap control technique for a digitally controlled NIBB converter. The proposed technique offers two duty cycle limitations for various conditions in the mode-transition region and ensures the stability of the digital controller and output voltage. Moreover, this technique involves combining the duty cycles of both step-down and step-up modes for deriving an accurate value of the output voltage. The experimental results derived from a digital controller implemented through a field-programmable-gate-array-based platform revealed that the output voltage of the NIBB converter was stable throughout the transition region. The observed input voltage of the converter, provided by a Li-ion battery, was 2.5–4.5 V, and the output voltage was typically 3.3 V, which is suitable for communication systems, audio systems, and I/O pad power supplies. The switching frequency was 1 MHz, and the maximum load current was 500 mA.
Autors: Yi-Yang Tsai;Yu-Shin Tsai;Chien-Wu Tsai;Chien-Hung Tsai;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jan 2017, volume: 64, issue:1, pages: 41 - 45
Publisher: IEEE
 
» Direct Control of the Inverter Impedance to Achieve Controllable Harmonic Sharing in the Islanded Microgrid
Abstract:
Harmonic current sharing is an important aspect of islanded microgrid due to the presence of nonlinear loads. The existing harmonic current sharing strategies suggest a tradeoff between voltage quality and harmonic sharing effectiveness. In this paper, a novel control strategy is proposed to achieve current harmonic sharing by directly controlling the inherent impedance of the inverter. The proposed technique achieves harmonic sharing, in a distributed generation (DG)-based islanded microgrid, without using any communication infrastructure. This paper also proposes a droop technique to distribute the harmonics generated by the nonlinear load as per the kVA ratings of different DG units in the system. The proposed concept of variable inverter impedance and its application in an islanded microgrid is validated using experimental studies.
Autors: Preetha Sreekumar;Vinod Khadkikar;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jan 2017, volume: 64, issue:1, pages: 827 - 837
Publisher: IEEE
 
» Direct Integration 3-D FDTD Method for Single-Species Cold Magnetized Plasma
Abstract:
Finite-difference equations for 3-D single-species cold magnetized plasma EM propagation are systematically generated using a new, algorithmic approach for generating finite-difference time-domain (FDTD) updates. This new approach is then generalized to handle systems with complex dispersion of arbitrarily high-order. It is shown how this results in the second-order accurate algorithms with numerical dispersion relations that can always be cast in the form of continuum dispersion counterparts via simple substitutions, avoiding laborious analysis. This allowed here the first reporting of a numerical Appleton–Hartree equation. The problem of field collocation is handled by the repetition of the Yee algorithm so that all field variables are defined at the corners of a new cubic computational cell. This cell offers new properties, such as full-vector control of the solution at each node. A new technique for deriving the stability condition is introduced to FDTD and shows that the new method has retained the same stability criterion of free-space propagation. Several simulation results are presented, one of which reveals a previously unreported problem, common to some gyrotropic methods—the tendency for spurious fields to arise at source locations. It is shown how this spuriousness, which has contaminated the results of a previous report, may be removed.
Autors: Eric Gamliel;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2017, volume: 65, issue:1, pages: 295 - 308
Publisher: IEEE
 
» Direct Modulation of a Laser Using 112-Gb/s 16-QAM Nyquist Subcarrier Modulation
Abstract:
A 112-Gb/s single-carrier, single-polarization short reach transmission system using a high bandwidth 1310 nm directly modulated laser is demonstrated. Spectrally efficient signal generation is achieved by using: 1) half-cycle Nyquist subcarrier modulation with 16-ary quadrature-amplitude-modulation; 2) pre-compensation for the frequency response of the end-to-end system; and 3) and a Volterra nonlinear equalizer to post-compensate for the nonlinear modulation dynamics of the laser. Digital signal processing techniques for signal recovery enable transmission over 20 km of standard single mode fiber with a bit error ratio below the 7% overhead hard-decision forward error correction coding threshold of at a received optical power of −5.25 dBm.
Autors: Yuliang Gao;John C. Cartledge;Aazar S. Kashi;Scott S.-H. Yam;Yasuhiro Matsui;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2017, volume: 29, issue:1, pages: 35 - 38
Publisher: IEEE
 
» Direct Parametric Reconstruction With Joint Motion Estimation/Correction for Dynamic Brain PET Data
Abstract:
Direct reconstruction of parametric images from raw photon counts has been shown to improve the quantitative analysis of dynamic positron emission tomography (PET) data. However it suffers from subject motion which is inevitable during the typical acquisition time of 1–2 hours. In this work we propose a framework to jointly estimate subject head motion and reconstruct the motion-corrected parametric images directly from raw PET data, so that the effects of distorted tissue-to-voxel mapping due to subject motion can be reduced in reconstructing the parametric images with motion-compensated attenuation correction and spatially aligned temporal PET data. The proposed approach is formulated within the maximum likelihood framework, and efficient solutions are derived for estimating subject motion and kinetic parameters from raw PET photon count data. Results from evaluations on simulated [11C]raclopride data using the Zubal brain phantom and real clinical [18F]florbetapir data of a patient with Alzheimer’s disease show that the proposed joint direct parametric reconstruction motion correction approach can improve the accuracy of quantifying dynamic PET data with large subject motion.
Autors: Jieqing Jiao;Alexandre Bousse;Kris Thielemans;Ninon Burgos;Philip S. J. Weston;Jonathan M. Schott;David Atkinson;Simon R. Arridge;Brian F. Hutton;Pawel Markiewicz;Sébastien Ourselin;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jan 2017, volume: 36, issue:1, pages: 203 - 213
Publisher: IEEE
 
» Direction-of-Arrival Estimation and Sensor Array Error Calibration Based on Blind Signal Separation
Abstract:
We consider estimating the direction-of-arrival (DOA) in the presence of sensor array error. In the proposed method, a blind signal separation method, the joint approximation and diagonalization of eigenmatrices algorithm, is implemented to separate the signal vector and the mixing matrix consisting of the array manifold matrix and the sensor array error matrix. Based on a new mixing matrix and the reconstruction of the array output vector of each individual signal, we propose a novel DOA estimation and sensor array error calibration procedure. This method is independent of array phase errors and performs well against difference of SNR of signals. Numerical simulations verify the effectiveness of the proposed method.
Autors: Jianfei Liu;Xiongbin Wu;William J. Emery;Lan Zhang;Chuan Li;Ketao Ma;
Appeared in: IEEE Signal Processing Letters
Publication date: Jan 2017, volume: 24, issue:1, pages: 7 - 11
Publisher: IEEE
 
» Directional Full-Duplex RF Booster for 2450 MHz ISM Band
Abstract:
A directional repeater system with simple architecture composed of wideband receive and transmit antennas, a high gain low-power amplifier, and a bandpass filter is proposed for the 2450-MHz ISM band. The repeater system does not require down-conversion and up-conversion with frequency translation and does not rely on any operational protocol to manage users. As a result, the repeater (RF booster) can support all users, channels, modulation themes, and devices simultaneously. Close to 70 dB of isolation between the Tx and Rx antennas over the entire band (~100 MHz) is achieved for a compact structure with lateral dimensions of 8 cm 12 cm and thickness of 1 cm. The isolation between the Tx and Rx antennas is achieved using polarization mismatch between orthogonal double-stack patch antennas and a novel two-element Rx antenna whose elements are appropriately located with respect to the Tx antenna to cancel the signal leakage from the Tx antenna to the Rx antennas. Two types of repeaters, one utilizing only the ground plane and polarization mismatch, and the second using the two-element Rx antenna in addition to polarization mismatch, are fabricated and tested in different environments. It is shown that more than 30 dB improvement in coverage can be achieved.
Autors: Mani Kashanianfard;Kamal Sarabandi;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2017, volume: 65, issue:1, pages: 134 - 141
Publisher: IEEE
 
» Directional Kernel Density Estimation for Classification of Breast Tissue Spectra
Abstract:
In Breast Conserving Therapy, surgeons measure the thickness of healthy tissue surrounding an excised tumor (surgical margin) via post-operative histological or visual assessment tests that, for lack of enough standardization and reliability, have recurrence rates in the order of 33%. Spectroscopic interrogation of these margins is possible during surgery, but algorithms are needed for parametric or dimension reduction processing. One methodology for tumor discrimination based on dimensionality reduction and nonparametric estimation—in particular, Directional Kernel Density Estimation—is proposed and tested on spectral image data from breast samples. Once a hyperspectral image of the tumor has been captured, a surgeon assists by establishing Regions of Interest where tissues are qualitatively differentiable. After proper normalization, Directional KDE is used to estimate the likelihood of every pixel in the image belonging to each specified tissue class. This information is enough to yield, in almost real time and with 98% accuracy, results that coincide with those provided by histological H&E validation performed after the surgery.
Autors: Arturo Pardo;Eusebio Real;Venkat Krishnaswamy;José Miguel López-Higuera;Brian W. Pogue;Olga M. Conde;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jan 2017, volume: 36, issue:1, pages: 64 - 73
Publisher: IEEE
 
» Dirichlet Process Gaussian Mixture Models for Real-Time Monitoring and Their Application to Chemical Mechanical Planarization
Abstract:
The goal of this work is to use sensor data for online detection and identification of process anomalies (faults). In pursuit of this goal, we propose Dirichlet process Gaussian mixture (DPGM) models. The proposed DPGM models have two novel outcomes: 1) DP-based statistical process control (SPC) chart for anomaly detection and 2) unsupervised recurrent hierarchical DP clustering model for identification of specific process anomalies. The presented DPGM models are validated using numerical simulation studies as well as wireless vibration signals acquired from an experimental semiconductor chemical mechanical planarization (CMP) test bed. Through these numerically simulated and experimental sensor data, we test the hypotheses that DPGM models have significantly lower detection delays compared with SPC charts in terms of the average run length (ARL1) and higher defect identification accuracies (F-score) than popular clustering techniques, such as mean shift. For instance, the DP-based SPC chart detects pad wear anomaly in CMP within 50 ms, as opposed to over 140 ms with conventional control charts. Likewise, DPGM models are able to classify different anomalies in CMP.
Autors: Jia Peter Liu;Omer F. Beyca;Prahalad K. Rao;Zhenyu James Kong;Satish T. S. Bukkapatnam;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jan 2017, volume: 14, issue:1, pages: 208 - 221
Publisher: IEEE
 
» Disclosure of Double Exchange Bias Effect in Chromium (III) Oxide Nanoparticles
Abstract:
In the last decade, the renewed interest in antiferromagnetic (AF) magnetoelectric (ME) materials has been driven by the challenging multifunctionality of spintronic devices. One of the most ambitious goals is to build exchange-biased ferromagnetic/AF junctions with electric field-controlled properties. In this context, the understanding of the modifications that size reduction induces in the magnetic properties of a material being both AF and ME holds the key to control the magnetic coupling at the interface. Here, we show that the spin arrangement in chromium (III) oxide core/shell nanoparticles changes significantly as a function of the radial distance from the nanoparticle center. While the nanoparticle core retains an AF structure, magnetic moments located on a thin surface shell are in a disordered spin-glass (SG)-like state. In addition, canted spins develop at the boundary of the ME AF core. These spins, which mediate a moderate AF/SG exchange coupling at low temperature, are exchange coupled to the AF core, thus giving rise to a lower yet more robust exchange bias effect, which persists up to the Néel temperature of the AF core.
Autors: Natalia Rinaldi-Montes;Pedro Gorria;Antonio B. Fuertes;David Martínez-Blanco;Luca Olivi;Inés Puente-Orench;Javier Alonso;Manh-Huong Phan;Hariharan Srikanth;Xavi Marti;Jesús A. Blanco;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jan 2017, volume: 53, issue:1, pages: 1 - 4
Publisher: IEEE
 
» Discovering New Worlds: A review of signal processing methods for detecting exoplanets from astronomical radial velocity data [Applications Corner]
Abstract:
Exoplanets, short for extra solar planets, are planets outside our solar system. They are objects with masses fewer than around 15 Jupiter-masses that orbit stars other than the sun. They are small enough so they cannot burn deuterium in their cores, yet large enough that they are not so-called dwarf planets like Pluto.
Autors: Muhammad Salman Khan;James Jenkins;Nestor Becerra Yoma;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2017, volume: 34, issue:1, pages: 104 - 115
Publisher: IEEE
 
» Discretization-Based and Look-Ahead Algorithms for the Dubins Traveling Salesperson Problem
Abstract:
A new class of discretization-based look-ahead algorithms (DLAAs) for the Dubins traveling salesperson problem (DTSP) is presented that compares favorably with the existing algorithms from the literature. The discretization level and the length of the look-ahead horizon are the two parameters that uniquely determine a DLAA, and depending on the application in hand, their values can be easily modified to strike a balance between the execution time and the length of the resulting admissible tour. The time complexity of a DLAA is the sum of two terms, one linear in the number of targets (cities) and one that corresponds to the specification of an initial order for the targets. For instances of the DTSP with densely distributed targets, an algorithm that relies on clustering and leads to shorter tours than the DLAA is also presented.
Autors: Izack Cohen;Chen Epstein;Pantelis Isaiah;Saar Kuzi;Tal Shima;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jan 2017, volume: 14, issue:1, pages: 383 - 390
Publisher: IEEE
 
» Discriminative and Efficient Label Propagation on Complementary Graphs for Multi-Object Tracking
Abstract:
Given a set of detections, detected at each time instant independently, we investigate how to associate them across time. This is done by propagating labels on a set of graphs, each graph capturing how either the spatio-temporal or the appearance cues promote the assignment of identical or distinct labels to a pair of detections. The graph construction is motivated by a locally linear embedding of the detection features. Interestingly, the neighborhood of a node in appearance graph is defined to include all the nodes for which the appearance feature is available (even if they are temporally distant). This gives our framework the uncommon ability to exploit the appearance features that are available only sporadically. Once the graphs have been defined, multi-object tracking is formulated as the problem of finding a label assignment that is consistent with the constraints captured each graph, which results into a difference of convex (DC) program. We propose to decompose the global objective function into node-wise sub-problems. This not only allows a computationally efficient solution, but also supports an incremental and scalable construction of the graph, thereby making the framework applicable to large graphs and practical tracking scenarios. Moreover, it opens the possibility of parallel implementation.
Autors: Amit Kumar K.C.;Laurent Jacques;Christophe De Vleeschouwer;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2017, volume: 39, issue:1, pages: 61 - 74
Publisher: IEEE
 
» Dissecting GPU Memory Hierarchy Through Microbenchmarking
Abstract:
Memory access efficiency is a key factor in fully utilizing the computational power of graphics processing units (GPUs). However, many details of the GPU memory hierarchy are not released by GPU vendors. In this paper, we propose a novel fine-grained microbenchmarking approach and apply it to three generations of NVIDIA GPUs, namely Fermi, Kepler, and Maxwell, to expose the previously unknown characteristics of their memory hierarchies. Specifically, we investigate the structures of different GPU cache systems, such as the data cache, the texture cache and the translation look-aside buffer (TLB). We also investigate the throughput and access latency of GPU global memory and shared memory. Our microbenchmark results offer a better understanding of the mysterious GPU memory hierarchy, which will facilitate the software optimization and modelling of GPU architectures. To the best of our knowledge, this is the first study to reveal the cache properties of Kepler and Maxwell GPUs, and the superiority of Maxwell in shared memory performance under bank conflict.
Autors: Xinxin Mei;Xiaowen Chu;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jan 2017, volume: 28, issue:1, pages: 72 - 86
Publisher: IEEE
 
» Dissipativity for a Class of Stochastic Nonlinear Systems With State-Dependent Switching
Abstract:
Dissipativity of stochastic nonlinear systems with state-dependent switching is investigated in this brief. Switching instants are introduced reasonably, based on the evolution of the state trajectory, which are proved to be stopping times. They are the key to apply Itô’s formula and Dynkin’s formula in stochastic systems. Based on these stopping times, some sufficient conditions on dissipativity of switched stochastic systems are provided. Furthermore, the criteria on global asymptotic stability and input-to-state stability in probability are presented by using a common Lyapunov function technique and multiple Lyapunov functions techniques, respectively. Finally, a numerical example is given to illustrate the validity of our results.
Autors: Dianfeng Zhang;Xi-Ming Sun;Zhaojing Wu;Wei Wang;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jan 2017, volume: 64, issue:1, pages: 86 - 90
Publisher: IEEE
 
» Distance-Based Cycle-Free Persistent Formation: Global Convergence and Experimental Test With a Group of Quadcopters
Abstract:
In this paper, distributed formation control for multi-agent systems is considered. The proposed control laws are designed to globally obtain and keep the desired formation in a two-dimensional space. It is assumed that the local frames of the agents are not aligned with each other and each agent does not know the orientation of others’ coordinate frames. Further, the agent measures only relative positions of neighbors with respect to the local reference frame. Therefore, the control of the system is completely decentralized and the global convergence is achieved without the global reference frame. The stability and convergence of the system are analyzed mathematically and the experiment using quadcopters is performed to verify the results of the theoretical analysis. In addition, the ambiguity problem and time-varying velocity case are also handled and discussed.
Autors: Sung-Mo Kang;Myoung-Chul Park;Hyo-Sung Ahn;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jan 2017, volume: 64, issue:1, pages: 380 - 389
Publisher: IEEE
 
» Distinguishing Heavy-Metal Stress Levels in Rice Using Synthetic Spectral Index Responses to Physiological Function Variations
Abstract:
Accurately assessing the heavy-metal contamination in crops is crucial to food security. This study provides a method to distinguish heavy-metal stress levels in rice using the variations of two physiological functions as discrimination indices, which are obtained by assimilation of remotely sensed data with a crop growth model. Two stress indices, which correspond to daily total assimilation and dry-matter conversion coefficient were incorporated into the World Food Study (WOFOST) crop growth model and calculated by assimilating the model with leaf area index (LAI), which was derived from time-series HJ1-CCD data. The stress levels are not constant with rice growth; thus, to improve the reliability, the two stress indices were obtained at both the first and the latter half periods of rice growth. To compare the stress indices of different stress levels, a synthetic stress index was established by combining the two indices; then, three types of stress index discriminant spaces based on the synthetic index of different growth periods were constructed, in which the two-dimensional discriminant space based on two growth periods showed the highest accuracy, with a misjudgment rate of 4.5%. When the discrimination rules were applied at a regional scale, the average correct discrimination rate was 95.0%.
Autors: Ming Jin;Xiangnan Liu;Ling Wu;Meiling Liu;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Jan 2017, volume: 10, issue:1, pages: 75 - 86
Publisher: IEEE
 
» Distortion Magnetic Field Compensation of Geomagnetic Vector Measurement System Using a 3-D Helmholtz Coil
Abstract:
The magnetic interferential fields, such as soft-iron and hard-iron interferences, will seriously affect the accuracy of geomagnetic vector measurement system, and thus should be compensated. In this letter, a new compensation method using a 3-D Helmholtz coil is proposed. As a first step, the geomagnetic vector measurement system is exposed to different directions and the magnitudes of magnetic field generated by a 3-D Helmholtz coil to construct the equations of error model, and soft-iron parameters can be estimated by solving linear equations. Then, hard-iron parameters are estimated by changing the fixation direction of the three-axis magnetometer. Finally, all the estimated parameters are used for compensating distortion magnetic fields. In order to verify the effectiveness of the proposed method, the experiment is conducted, and the results demonstrate that the proposed method contributes to the accuracy improvement of geomagnetic vector measurement system.
Autors: Zhongyan Liu;Qi Zhang;Mengchun Pan;Qingxiao Shan;Yunling Geng;Feng Guan;Dixiang Chen;Wugang Tian;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jan 2017, volume: 14, issue:1, pages: 48 - 51
Publisher: IEEE
 
» Distributed Channel Access for Device-to-Device Communications: A Hypergraph-Based Learning Solution
Abstract:
In this letter, we propose a learning solution for distributed channel access in device-to-device communications based on a hypergraph interference model. We first define a new interference metric for a hypergraph model, and then formulate this distributed channel access problem as a local altruistic game, which is proved to be an exact potential game admitting at least one pure strategy Nash equilibrium (PNE). A distributed learning algorithm is designed to quickly achieve the optimal PNE, which can minimize the defined networks’ interference metric. Simulation results show that the proposed algorithm outperforms the existing schemes and significantly improves the spectrum efficiency.
Autors: Youming Sun;Qihui Wu;Yuhua Xu;Yuli Zhang;Fenggang Sun;Jinlong Wang;
Appeared in: IEEE Communications Letters
Publication date: Jan 2017, volume: 21, issue:1, pages: 180 - 183
Publisher: IEEE
 
» Distributed Evaluation and Convergence of Self-Appraisals in Social Networks
Abstract:
We consider in this paper a networked system of opinion dynamics in continuous time, where the agents are able to evaluate their self-appraisals in a distributed way. In the model we formulate, the underlying network topology is described by a rooted digraph. For each ordered pair of agents , we assign a function of self-appraisal to agent , which measures the level of importance of agent to agent . Thus, by communicating only with her neighbors, each agent is able to calculate the difference between her level of importance to others and others' level of importance to her. The dynamical system of self-appraisals is then designed to drive these differences to zero. We show that for almost all initial conditions, the trajectory generated by this dynamical system asymptotically converges to an equilibrium point which is exponentially stable.
Autors: Xudong Chen;Ji Liu;Mohamed-Ali Belabbas;Zhi Xu;Tamer Başar;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jan 2017, volume: 62, issue:1, pages: 291 - 304
Publisher: IEEE
 
» Distributed Frequency Control Through MTDC Transmission Systems
Abstract:
In this paper, we propose distributed dynamic controllers for sharing both frequency containment and restoration reserves of asynchronous ac systems connected through a multi-terminal HVDC (MTDC) grid. The communication structure of the controller is distributed in the sense that only local and neighboring state information is needed, rather than the complete state. We derive sufficient stability conditions, which guarantee that the ac frequencies converge to the nominal frequency. Simultaneously, a global quadratic power generation cost function is minimized. The proposed controller also regulates the voltages of the MTDC grid, asymptotically minimizing a quadratic cost function of the deviations from the nominal dc voltages. The results are valid for distributed cable models of the HVDC grid (e.g., -links), as well as ac systems of arbitrary number of synchronous machines, each modeled by the swing equation. We also propose a decentralized communication-free version of the controller. The proposed controllers are tested on a high-order dynamic model of a power system consisting of asynchronous ac grids, modeled as IEEE 14 bus networks, connected through a six-terminal HVDC grid. The performance of the controller is successfully evaluated through simulation.
Autors: Martin Andreasson;Roger Wiget;Dimos V. Dimarogonas;Karl H. Johansson;Göran Andersson;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jan 2017, volume: 32, issue:1, pages: 250 - 260
Publisher: IEEE
 
» Distributed Generation Control Method for Active Power Sharing and Self-Frequency Recovery in an Islanded Microgrid
Abstract:
This paper describes a control method for distributed generation (DG) units to implement active power sharing and frequency recovery simultaneously in an islanded microgrid. Conventional active power–frequency (P f) droop control is used for the DG controller, and the frequency deviation is recovered by the DG itself via self-frequency recovery control, without requiring secondary frequency control. Because the electrical distance (impedance) from each DG unit to a point where the load demand changes differs among DG units, the instantaneous frequency deviations may differ between DG units. These differences are fed into the integrators of the self-frequency recovery control and may result in errors in active power sharing. To solve this problem and share active power more accurately, a compensation control method is developed for active power sharing, which considers the droop coefficients of each of the DG units. Simulation results show that the proposed control method is effective.
Autors: Yun-Su Kim;Eung-Sang Kim;Seung-Il Moon;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jan 2017, volume: 32, issue:1, pages: 544 - 551
Publisher: IEEE
 
» Distributed MIMO Broadcasting: Reverse Compute-and-Forward and Signal-Space Alignment
Abstract:
We study a downlink distributed MIMO system where a central unit (CU) broadcasts messages to users through distributed BSs. The CU is connected to the BSs via independent rate-constrained fronthaul (FH) links. The distributed BSs collectively serve the users through the air. We propose a new network coding based distributed MIMO broadcasting scheme, using reverse compute-and-forward and signal-space alignment. At the CU, a network coding generator matrix is employed for pre network coding of the users’ messages. The network coded messages are forwarded to the BSs, where the FH rate-constraint determines the actual number of network-coded messages forwarded to the BSs. At the BSs, linear precoding matrices are designed to create a number of bins, each containing a bunch of spatial streams with aligned signal-spaces. At each user, post physical-layer network coding is employed to compute linear combinations over the NC messages with respect to the bins, which reverses the prenetwork coding and recovers the desired messages. We derive an achievable rate of the proposed scheme based on the existence of NC generator matrix, signal-space alignment precoding matrices, and nested lattice codes. Improved rate and degrees of freedom over existing interference alignment and compress-and-forward schemes are shown. Numerical results demonstrate the performance improvement, e.g., by as much as 70% increase in throughput over benchmark schemes.
Autors: Tao Yang;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2017, volume: 16, issue:1, pages: 581 - 593
Publisher: IEEE
 
» Distributed MIMO Multicast With Protected Receivers: A Scalable Algorithm for Joint Beamforming and Nullforming
Abstract:
We consider the problem of multicasting a common message signal from a distributed array of wireless transceivers by beamforming to a set of beam targets, while simultaneously protecting a set of null targets by nullforming to them. We describe a distributed algorithm in which each transmitter iteratively adapts its complex transmit weight using common aggregate feedback messages broadcast by the targets, and the local knowledge of only its own channel gains to the targets. This knowledge can be obtained using reciprocity without any explicit feedback. The algorithm minimizes the mean square error between the complex signal amplitudes at the targets and their desired values. We prove convergence of the algorithm, present geometric interpretations, characterize initializations that lead to minimum total transmit power, and prescribe designs for such initializations. We show that the convergence speed is nondecreasing in the number of transmitters if a step size parameter is kept constant. For Rayleigh fading channels, as goes to infinity: 1) convergence can be made arbitrarily fast and 2) beams and nulls can be achieved with vanishing total transmit power even with noise, both with probability one. These results add up to some remarkable scalability properties: the feedback overhead does not grow with the number of transmitters, and with high probability, the algorithm can be configured to converge arbitrarily fast and use vanishingly small total transmit power.
Autors: Amy Kumar;Raghuraman Mudumbai;Soura Dasgupta;Upamanyu Madhow;D. Richard Brown;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2017, volume: 16, issue:1, pages: 512 - 525
Publisher: IEEE
 
» Distributed Multicast Tree Construction in Wireless Sensor Networks
Abstract:
Multicast tree is a key structure for data dissemination from one source to multiple receivers in wireless networks. Minimum length multica modeled as the Steiner tree problem, and is proven to be NP-hard. In this paper, we explore how to efficiently generate minimum length multi wireless sensor networks (WSNs), where only limited knowledge of network topology is available at each node. We design and analyze a simple algorithm, which we call toward source tree (TST), to build multicast trees in WSNs. We show three metrics of TST algorithm, i.e., running and energy efficiency. We prove that its running time is , the best among all existing solutions to our best knowledge. We prove that TST tree length is in the same order as Steiner tree, which give a theoretical upper bound and use simulations to show the ratio be only 1.114 when nodes are uniformly distributed. We evaluate energy efficiency in terms of message complexity and the number of forwarding prove that they are both order-optimal. We give an efficient way to construct multicast tree in support of transmission of voluminous data.
Autors: Hongyu Gong;Luoyi Fu;Xinzhe Fu;Lutian Zhao;Kainan Wang;Xinbing Wang;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jan 2017, volume: 63, issue:1, pages: 280 - 296
Publisher: IEEE
 
» Distributed Robust Bilinear State Estimation for Power Systems with Nonlinear Measurements
Abstract:
This paper proposes a fully distributed robust bilinear state-estimation (D-RBSE) method that is applicable to multi-area power systems with nonlinear measurements. We extend the recently introduced bilinear formulation of state estimation problems to a robust model. A distributed bilinear state-estimation procedure is developed. In both linear stages, the state estimation problem in each area is solved locally, with minimal data exchange with its neighbors. The intermediate nonlinear transformation can be performed by all areas in parallel without any need of inter-regional communication. This algorithm does not require a central coordinator and can compress bad measurements by introducing a robust state estimation model. Numerical tests on IEEE 14-bus, 118-bus benchmark systems, and a 1062-bus system demonstrate the validity of the method.
Autors: Weiye Zheng;Wenchuan Wu;Antonio Gomez-Exposito;Boming Zhang;Ye Guo;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jan 2017, volume: 32, issue:1, pages: 499 - 509
Publisher: IEEE
 
» Distributed Structure: Joint Expurgation for the Multiple-Access Channel
Abstract:
In this paper, we obtain an improved lower bound on the error exponent of the memoryless multiple-access channel via the use of linear codes, thus demonstrating that structure can be beneficial even when capacity may be achieved via random codes. We show that if the multiple-access channel is additive over a finite field, then any error probability, and hence any error exponent, achievable by a linear code for the associated single-user channel, is also achievable for the multiple-access channel. In particular, linear codes allow to attain joint expurgation, and hence, attain the single-user expurgated exponent of the single-user channel, whenever the latter is achieved by a uniform distribution. Thus, for additive channels, at low rates, where expurgation is needed, our approach strictly improves performance over previous results, where expurgation was used for at most one of the users. Even when the multiple-access channel is not additive, it may be transformed into such a channel. While the transformation is information-lossy, we show that the distributed structure gain in some “nearly additive” cases outweighs the loss. Finally, we apply a similar approach to the Gaussian multiple-access channel. While we believe that due to the power constraints, it is impossible to attain the single-user error exponent, we do obtain an improvement over the best known achievable error exponent, given by Gallager, for certain parameters. This is accomplished using a nested lattice triplet with judiciously chosen parameters.
Autors: Eli Haim;Yuval Kochman;Uri Erez;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jan 2017, volume: 63, issue:1, pages: 5 - 20
Publisher: IEEE
 
» Diversity-Multiplexing Tradeoff in an Interweave Multiuser Cognitive Radio System
Abstract:
In an interweave cognitive radio system, the spectrum sensing performance affects the rate and reliability of data transmission. In wireless communications, the tradeoff between the reliability and data rate can be evaluated by diversity-multiplexing tradeoff (DMT) analysis. In this paper, through the analysis of the error probability at the secondary receiver, we derive the DMT for the multiple-access channel and user-selection schemes in an interweave multiuser cognitive radio system considering the spectrum sensing effect on the rate and reliability. We show that the DMT of the system can be improved by cooperative spectrum sensing. Simulations also approve our analytical results.
Autors: Atefeh Roostaei;Mostafa Derakhtian;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2017, volume: 16, issue:1, pages: 389 - 399
Publisher: IEEE
 
» DIVERT: A Distributed Vehicular Traffic Re-Routing System for Congestion Avoidance
Abstract:
Centralized solutions for vehicular traffic re-routing to alleviate congestion suffer from two intrinsic problems: scalability, as the central server has to perform intensive computation and communication with the vehicles in real-time; and privacy, as the drivers have to share their location as well as the origins and destinations of their trips with the server. This article proposes DIVERT, a distributed vehicular re-routing system for congestion avoidance. DIVERT offloads a large part of the re-routing computation at the vehicles, and thus, the re-routing process becomes practical in real-time. To take collaborative re-routing decisions, the vehicles exchange messages over vehicular ad hoc networks. DIVERT is a hybrid system because it still uses a server and Internet communication to determine an accurate global view of the traffic. In addition, DIVERT balances the user privacy with the re-routing effectiveness. The simulation results demonstrate that, compared with a centralized system, the proposed hybrid system increases the user privacy by 92 percent on average. In terms of average travel time, DIVERT's performance is slightly less than that of the centralized system, but it still achieves substantial gains compared to the no re-routing case. In addition, DIVERT reduces the CPU and network load on the server by 99.99 and 95 percent, respectively.
Autors: Juan (Susan) Pan;Iulian Sandu Popa;Cristian Borcea;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2017, volume: 16, issue:1, pages: 58 - 72
Publisher: IEEE
 
» DOA Estimation Based on Combined Unitary ESPRIT for Coprime MIMO Radar
Abstract:
Direction of arrival (DOA) estimation for coprime multiple-input multiple-output radar is studied, and a combined unitary estimation of signal parameters via rotational invariance technique (ESPRIT)-based algorithm is proposed. The transmitter and the receiver adopt coprime arrays, which are sparse but still uniform. Therefore, unitary ESPRIT is first used to obtain arbitrary ambiguous DOA estimations based on the rotational invariances of transmit and receive arrays, respectively. After recovering all the other estimations, unique DOA estimation is achieved by finding the coincide results from transmit and receive arrays based on the coprimeness. The proposed algorithm obtains more accurate DOA estimation, achieves higher angle resolution, and identifies more targets than conventional methods. Multiple simulations are conducted to verify the improvement of the proposed algorithm.
Autors: Jianfeng Li;Defu Jiang;Xiaofei Zhang;
Appeared in: IEEE Communications Letters
Publication date: Jan 2017, volume: 21, issue:1, pages: 96 - 99
Publisher: IEEE
 
» Doubly Fed Induction Generator System Resonance Active Damping Through Stator Virtual Impedance
Abstract:
The penetration of wind power has been increasing in the past few decades all over the world. Under certain nonideal situations where the wind power generation system is connected to the weak grid, the doubly fed induction generator (DFIG)-based wind power generation system may suffer high-frequency resonance (HFR) due to the impedance interaction between the DFIG system and the weak grid network whose impedance is comparatively large. Thus, it is important to implement an active damping for the HFR in order to ensure a safe and reliable operation of both the DFIG system and the grid-connected converters/loads. This paper analyzes and explains first the HFR phenomenon between the DFIG system and a parallel compensated weak network (series RL + shunt C). Then, on the basis of the DFIG system impedance modeling, an active damping control strategy is introduced by inserting a virtual impedance (positive capacitor or negative inductor) into the stator branch through stator current feedforward control. The effectiveness of the DFIG system active damping control is verified by a 7.5 kW experimental downscaled DFIG system, and simulation results of a commercial 2 MW DFIG system is provided as well.
Autors: Yipeng Song;Xiongfei Wang;Frede Blaabjerg;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jan 2017, volume: 64, issue:1, pages: 125 - 137
Publisher: IEEE
 
» Downscaling of Land Surface Temperature Using Airborne High-Resolution Data: A Case Study on Aprilia, Italy
Abstract:
A regression-based downscaling of land surface temperature was developed over the heterogeneous urban area of Aprilia, Central Italy, using high resolution (HR) airborne data. Airborne sensors provided thermal and visible–near infrared (VNIR) measurements at 2-m pixel size. Coarse resolution images at 40, 30, and 20 m, upscaled by aggregation from the native airborne data, were sharpened to the finer resolution of 2 m. The main core of the downscaling method is the use of the spectral mixture analysis (SMA) to derive fractional pixel composition as predictors of the regression scheme. The HR VNIR data allow choosing detailed land cover types in the application of SMA, such as bright/dark roofs, and the benefit of this detailed selection is proved. The estimation error of the custom technique improves of about 10%–15% with respect to a classical regression downscaling.
Autors: Stefania Bonafoni;Grazia Tosi;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jan 2017, volume: 14, issue:1, pages: 107 - 111
Publisher: IEEE
 
» Drawing the Most Power From Low-Cost Single-Well 1-mm2 CMOS Photovoltaic Cells
Abstract:
Photovoltaic (PV) cells can generate 100× more power from light than other transducers can from motion, radiation, and heat. Although custom multijunction nonsilicon and multiwell complementary metal–oxide–semiconductor (CMOS) cells output more power, single-well process technologies cost less. Amorphous cells cost even less but output less power. However, with only a small window of light available, tiny CMOS cells output little. This brief explores and proposes open-terminal single-well CMOS PV cell configurations that output more power than competing low-cost CMOS cells in literature. Measurements with 0.35- single-well CMOS cells show that deeper and lighter doped junctions generate higher power than shallower junctions, and double-junction configurations output even higher power. This is why sunlight on N+ in P substrate and N well in P substrate cells outputs 6 and 98 and on shorted and open-terminal P+ in N well in P substrate structures outputs 132 . Opening the P+ terminal outputs even more power because P+ metal, which blocks light, is no longer necessary.
Autors: Rajiv Damodaran Prabha;Gabriel A. Rincón-Mora;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jan 2017, volume: 64, issue:1, pages: 46 - 50
Publisher: IEEE
 
» Drive Now, Text Later: Nonintrusive Texting-While-Driving Detection Using Smartphones
Abstract:
Texting-while-driving (T&D) is one of the top dangerous behaviors for drivers. Many interesting systems and mobile phone applications have been designed to help to detect or combat T&D. However, for a T&D detection system to be practical, a key property is its capability to distinguish driver's mobile phone from passengers’. Existing solutions to this problem generally rely on the user's manual input, or utilize specific localization devices to determine whether a mobile phone is at the driver's location. In this paper, we propose a method which is able to detect T&D automatically without using any extra devices. The idea is very simple: when a user is composing messages, the smartphone embedded sensors (i.e., gyroscopes, accelerometers, and GPS) collect the associated information such as touchstrokes, holding orientation and vehicle speed. This information will then be analyzed to see whether there exists some specific T&D patterns. Extensive experiments have been conducted by different persons and in different driving scenarios. The results show that our approach can achieve a good detection accuracy with low false positive rate. Besides being infrastructure-free and with high accuracy, the method does not access the content of messages and therefore is privacy-preserving.
Autors: Xuefeng Liu;Jiannong Cao;Shaojie Tang;Zongjian He;Jiaqi Wen;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2017, volume: 16, issue:1, pages: 73 - 86
Publisher: IEEE
 
» Driver Topologies for RF Doherty Power Amplifiers
Abstract:
In this letter, class-B, embedded class-B, and Doherty driver topologies are investigated for RF Doherty Power Amplifiers (PAs). The investigation is firstly conducted theoretically and by simulations and then verified by design and implementation of the different topologies at 2.1 GHz using GaN-HEMT transistors. The results show that the highest lineup efficiency can be achieved when using a Doherty driver. Modulated measurements using the same LTE signal and the same digital per-distorter (DPD), show about 2% and 4% higher average lineup efficiency when the Doherty driver is used compared to the class-B and embedded class-B drivers, respectively.
Autors: Paul Saad;Zahra Asghari;Christian Fager;Hossein Mashad Nemati;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jan 2017, volume: 27, issue:1, pages: 67 - 69
Publisher: IEEE
 
» Driving Toward Accessibility: A Review of Technological Improvements for Electric Machines, Power Electronics, and Batteries for Electric and Hybrid Vehicles
Abstract:
Electric and hybrid vehicles continue to demand a considerable share of the automotive market. This movement has been enabled by the recent technological improvements in the areas of electric motors, power electronics, and energy storage. While many electric vehicles (EVs) are on the market, they are not as cost competitive as conventional vehicles, and affordable cost is necessary for large-scale market penetration. For this to become a reality, continued research is needed to develop new cost-efficient technologies. This article presents the metrics and benchmarks used to gauge the performance of various electric drivetrains. In addition, current state-of-the-art technologies are presented in terms of these metrics as well as the future goals and trends in the industry. With ongoing development, the market for electric and hybrid vehicles will continue to increase.
Autors: Bulent Sarlioglu;Casey T. Morris;Di Han;Silong Li;
Appeared in: IEEE Industry Applications Magazine
Publication date: Jan 2017, volume: 23, issue:1, pages: 14 - 25
Publisher: IEEE
 
» Drone Classification Using Convolutional Neural Networks With Merged Doppler Images
Abstract:
We propose a drone classification method based on convolutional neural network (CNN) and micro-Doppler signature (MDS). The MDS only presents Doppler information in time domain. The frequency domain representation of MDS is called as cadence-velocity diagram (CVD). To analyze the Doppler information of drone in time and frequency domain, we propose a new image by merging MDS and CVD, as merged Doppler image. GoogLeNet, a CNN structure, is utilized for the proposed image data set because of its high performance and optimized computing resources. The image data set is generated by the returned Ku-band frequency modulation continuous wave radar signal. Proposed approach is tested and verified in two different environments, anechoic chamber and outdoor. First, we tested our approach with different numbers of operating motor and aspect angle of a drone. The proposed method improved the accuracy from 89.3% to 94.7%. Second, two types of drone at the 50 and 100 m height are classified and showed 100% accuracy due to distinct difference in the result images.
Autors: Byung Kwan Kim;Hyun-Seong Kang;Seong-Ook Park;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jan 2017, volume: 14, issue:1, pages: 38 - 42
Publisher: IEEE
 
» Drones Ripe for Pervasive Use
Abstract:
Initial drone research was mostly concerned with improving technical abilities--including battery power and flight accuracy. More recent research investigates how drones can support existing application domains and even create new ones. This special issue looks at some of this more recent research. Instead of looking at the larger drones mostly used during military operations, it focuses on smaller drones, which fly at lower altitudes and thus could play a more significant role in pervasive computing applications.
Autors: Florian Floyd Mueller;Albrecht Schmidt;
Appeared in: IEEE Pervasive Computing
Publication date: Jan 2017, volume: 16, issue:1, pages: 21 - 23
Publisher: IEEE
 
» Dual Polarized Planar Aperture Antenna on LTCC for 60-GHz Antenna-in-Package Applications
Abstract:
This paper presents a novel dual polarized planar aperture antenna using the low-temperature cofired ceramics technology to realize a novel antenna-in-package for a 60-GHz CMOS differential transceiver chip. Planar aperture antenna technology ensures high gain and wide bandwidth. Differential feeding is adopted to be compatible with the chip. Dual polarization makes the antenna function as a pair of single polarized antennas but occupies much less area. The antenna is ±45° dual polarized, and each polarization acts as either a transmitting (TX) or receiving (RX) antenna. This improves the signal-to-noise ratio of the wireless channel in a point-to-point communication, because the TX/RX polarization of one antenna is naturally copolarized with the RX/TX polarization of the other antenna. A prototype of the proposed antenna is designed, fabricated, and measured, whose size is 12 mm 12 mm mm (). The measurement shows that the −10 dB impedance bandwidth covers the entire 60 GHz unlicensed band (57–64 GHz) for both polarizations. Within the bandwidth, the isolation between the ports of the two polarizations is better than 26 dB, and the gain is higher than 10 dBi with a peak of around 12 dBi for both polarizations.
Autors: Shaowei Liao;Quan Xue;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2017, volume: 65, issue:1, pages: 63 - 70
Publisher: IEEE
 
» Dual-Gate Charge Trap Flash Memory for Highly Reliable Triple Level Cell Using Capacitive Coupling Effects
Abstract:
In this letter, the triple level cell (TLC) NAND flash memory with excellent properties was implemented by a thin film charge trap flash memory with a dual-gate structure by using the capacitive coupling effect between the front gate and back gate. As compared with the single-gate (SG) mode operation, a large memory window at low program and erase (P/E) voltages was obtained from the dual-gate (DG) mode operation owing to the capacitive coupled self-amplifying effect. The TLC was implemented by using the DG-mode operation with highly stable eight levels: a large threshold voltage difference >9 V per level was obtained under low operating voltages at <14 V with a fast P/E speed of . In contrast, the conventional SG mode was unfavorable to TLC. Furthermore, the DG mode showed a much smaller charge loss than the SG mode, resulting in stable retention and endurance characteristics at room temperature and high temperature.
Autors: Min-Ju Ahn;Won-Ju Cho;
Appeared in: IEEE Electron Device Letters
Publication date: Jan 2017, volume: 38, issue:1, pages: 36 - 39
Publisher: IEEE
 
» Dual-Tree Complex Wavelet Transform-Based Control Algorithm for Power Quality Improvement in a Distribution System
Abstract:
This paper presents a dual tree-complex wavelet transform-based control algorithm for a distribution static compensator (DSTATCOM) to improve the power quality (PQ) in a distribution system. PQ disturbances like harmonics and starting as well as ending of unbalancing in all phase load currents are also assessed simultaneously. The distorted load current of each phase is decomposed into various frequency levels with this technique to extract respective line frequency component for the estimation of the reference active power component. The deviations of respective sensed load currents from these estimated reference components are used to generate the reference currents for the control of voltage source converter used as DSTATCOM. Simulated performance of DSTATCOM is presented at varying load conditions. The proposed control algorithm is also validated experimentally on a laboratory prototype of DSTATCOM. The total harmonic distortion (THD) of supply current is obtained below 5 percent with unity power factor under different load conditions which is satisfactory as per IEEE-519 standard.
Autors: Raj Kumar;Bhim Singh;D. T. Shahani;Chinmay Jain;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jan 2017, volume: 64, issue:1, pages: 764 - 772
Publisher: IEEE
 
» Dynamic Dual-Reference Sensing Scheme for Deep Submicrometer STT-MRAM
Abstract:
As process technology downscales, read reliability has become a critical barrier for spin transfer torque magnetic random access memory (STT-MRAM), owing to the increasing process-temperature-voltage (PVT) variations, decreasing critical switching current of magnetic tunnel junction (MTJ) and supply voltage. To deal with the read reliability challenge, we propose herein a dynamic dual-reference sensing (DDRS) scheme. The key features of the proposed DDRS scheme include: (a) two reference signals, generated by two reference cells with the same structures as those of the data cells, are provided to the sensing circuit; (b) the reference signals are adaptively dynamical depending on the content stored in the target data cell; (c) two output signals are obtained to decide the sensing result, adding redundancy for supporting self-error detection (SED) capability. The proposed DDRS scheme can achieve a great improvement in sensing margin (SM) and bit error rate (BER), in comparison with conventional sensing schemes. In addition, no regularity problems exist in the proposed DDRS scheme, as the reference cells maintain exactly the same structures as those of the data cells. Our simulation results show that the proposed DDRS scheme can achieve a increase in average SM, and a ~ 70% reduction in average BER, compared with conventional sensing schemes.
Autors: Wang Kang;Tingting Pang;Weifeng Lv;Weisheng Zhao;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jan 2017, volume: 64, issue:1, pages: 122 - 132
Publisher: IEEE
 
» Dynamic Electrical Source Imaging (DESI) of Seizures and Interictal Epileptic Discharges Without Ensemble Averaging
Abstract:
We propose an algorithm for electrical source imaging of epileptic discharges that takes a data-driven approach to regularizing the dynamics of solutions. The method is based on linear system identification on short time segments, combined with a classical inverse solution approach. Whereas ensemble averaging of segments or epochs discards inter-segment variations by averaging across them, our approach explicitly models them. Indeed, it may even be possible to avoid the need for the time-consuming process of marking epochs containing discharges altogether. We demonstrate that this approach can produce both stable and accurate inverse solutions in experiments using simulated data and real data from epilepsy patients. In an illustrative example, we show that we are able to image propagation using this approach. We show that when applied to imaging seizure data, our approach reproducibly localized frequent seizure activity to within the margins of surgeries that led to patients’ seizure freedom. The same approach could be used in the planning of epilepsy surgeries, as a way to localize potentially epileptogenic tissue that should be resected.
Autors: Burak Erem;Damon E. Hyde;Jurriaan M. Peters;Frank H. Duffy;Simon K. Warfield;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jan 2017, volume: 36, issue:1, pages: 98 - 110
Publisher: IEEE
 
» Dynamic Games With Asymmetric Information: Common Information Based Perfect Bayesian Equilibria and Sequential Decomposition
Abstract:
We formulate and analyze a general class of stochastic dynamic games with asymmetric information arising in dynamic systems. In such games, multiple strategic agents control the system dynamics and have different information about the system over time. Because of the presence of asymmetric information, each agent needs to form beliefs about other agents' private information. Therefore, the specification of the agents' beliefs along with their strategies is necessary to study the dynamic game. We use Perfect Bayesian equilibrium (PBE) as our solution concept. A PBE consists of a pair of strategy profile and belief system. In a PBE, every agent's strategy should be a best response under the belief system, and the belief system depends on agents' strategy profile when there is signaling among agents. Therefore, the circular dependence between strategy profile and belief system makes it difficult to compute PBE. Using the common information among agents, we introduce a subclass of PBE called common information based perfect Bayesian equilibria (CIB-PBE), and provide a sequential decomposition of the dynamic game. Such decomposition leads to a backward induction algorithm to compute CIB-PBE. We illustrate the sequential decomposition with an example of a multiple access broadcast game. We prove the existence of CIB-PBE for a subclass of dynamic games.
Autors: Yi Ouyang;Hamidreza Tavafoghi;Demosthenis Teneketzis;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jan 2017, volume: 62, issue:1, pages: 222 - 237
Publisher: IEEE
 
» Dynamic Manga: Animating Still Manga via Camera Movement
Abstract:
We propose a method for animating still manga imagery through camera movements. Given a series of existing manga pages, we start by automatically extracting panels, comic characters, and balloons from the manga pages. Then, we use a data-driven graphical model to infer per-panel motion and emotion states from low-level visual patterns. Finally, by combining domain knowledge of film production and characteristics of manga, we simulate camera movements over the manga pages, yielding an animation. The results augment the still manga contents with animated motion that reveals the mood and tension of the story, while maintaining the original narrative. We have tested our method on manga series of different genres, and demonstrated that our method can generate animations that are more effective in storytelling and pacing, with less human efforts, as compared with prior works. We also show two applications of our method, mobile comic reading, and comic trailer generation.
Autors: Ying Cao;Xufang Pang;Antoni B. Chan;Rynson W. H. Lau;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jan 2017, volume: 19, issue:1, pages: 160 - 172
Publisher: IEEE
 
» Dynamic Rain Attenuation Model for Millimeter Wave Network Analysis
Abstract:
In millimeter wave networks, a received signal level and interference dynamically vary due to rain attenuation. These physical layer variations have influence on upper communication layers, which yield to variable network capabilities to serve traffic demands. Standards and agreements between service providers and users usually specify performance objectives at annual level. In order to make realistic annual level performance analysis of such networks, a new computationally efficient dynamic rain attenuation model is proposed and analyzed. The model reproduces assumed rain statistics at annual level: cumulative distribution function (cdf) of rain intensity, number of rain events in which specified rain intensity threshold is exceeded, rain advection vector intensity, and rain advection vector azimuth. Derivation of model parameter tolerances is based on the experimental results from dense rain gauge network. As an example of model application, annual level cdfs of node-to-node connection capacity in a test network are calculated.
Autors: Miroslav V. Perić;Dragana B. Perić;Branislav M. Todorović;Miroslav V. Popović;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2017, volume: 16, issue:1, pages: 441 - 450
Publisher: IEEE
 
» Dynamic Spectrum Management: A Complete Complexity Characterization
Abstract:
Consider a multi-user multi-carrier communication system where multiple users share multiple discrete subcarriers. To achieve high spectrum efficiency, the users in the system must choose their transmit power dynamically in response to fast channel fluctuations. Assuming perfect channel state information, two formulations for the spectrum management (power control) problem are considered in this paper: the first is to minimize the total transmission power subject to all users’ transmission data rate constraints, and the second is to maximize the min-rate utility subject to individual power constraints at each user. It is known in the literature that both formulations of the problem are polynomial time solvable when the number of subcarriers is one and strongly NP-hard when the number of subcarriers are greater than or equal to three. However, the complexity characterization of the problem when the number of subcarriers is two has been missing for a long time. This paper answers this long-standing open question: both formulations of the problem are strongly NP-hard when the number of subcarriers is two.
Autors: Ya-Feng Liu;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jan 2017, volume: 63, issue:1, pages: 392 - 403
Publisher: IEEE
 
» Dynamic Task Execution Using Active Parameter Identification With the Baxter Research Robot
Abstract:
This paper presents experimental results from the real-time parameter estimation of a system model and subsequent trajectory optimization for a dynamic task using the Baxter Research Robot from Rethink Robotics. An active estimator maximizing Fisher information is used in real time with a closed-loop, nonlinear control technique known as sequential action control. Baxter is tasked with estimating the length of a string connected to a load suspended from the gripper with a load cell providing the single source of feedback to the estimator. Following the active estimation, a trajectory is generated using the trep software package that controls Baxter to dynamically swing a suspended load into a box. Several trials are presented with varying initial estimates showing that the estimation is required to obtain adequate open-loop trajectories to complete the prescribed task. The result of one trial with and without the active estimation is also shown in the accompanying video.
Autors: Andrew D. Wilson;Jarvis A. Schultz;Alex R. Ansari;Todd D. Murphey;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jan 2017, volume: 14, issue:1, pages: 391 - 397
Publisher: IEEE
 
» E-Including the Illiterate
Abstract:
In present-day society, we communicate over the Internet in several media forms. We put videos and images online, listen to music made by famous bands or by our friends, and read and write a lot of text. Never in the history of mankind have we produced more text than at this present moment, so being able to read and write is an important way of taking part in our society. We tend to forget that, even in our educated communities, not all people can read or write and there exist several degrees of literateness. People with reduced cognitive capacities and those migrating from cultures with a different language, or even a completely different writing system, are excluded from fully taking part in written online communication: they are e-excluded.
Autors: Vincent Vandeghinste;Leen Sevens;Ineke Schuurman;
Appeared in: IEEE Potentials
Publication date: Jan 2017, volume: 36, issue:1, pages: 29 - 33
Publisher: IEEE
 
» EBSCam: Background Subtraction for Ubiquitous Computing
Abstract:
Background subtraction (BS) is a crucial machine vision scheme for detecting moving objects in a scene. With the advent of smart cameras, the embedded implementation of BS finds ever-increasing applications. This paper presents a new BS scheme called efficient BS for smart cameras (EBSCam). EBSCam thresholds the change in the estimated background model, which suppresses variance of the estimates, resulting in competitive performance compared with standard BS schemes. The percentage of wrong classification of EBSCam is lower than those of the Gaussian mixture model (GMM) (10.97%) and the pixel-based adaptive segmenter (PBAS) (4.66%) algorithms in FPGA implementations. Moreover, the memory bandwidth requirement of EBSCam is 6.66%, 41.36%, and 90.48% lower than the state-of-the-art FPGA implementation of GMM, ViBe, and PBAS algorithms, respectively. EBSCam achieves a significant speed up compared with the FPGA implementations of GMM (by 43.3%), ViBe (by 118.6%), and PBAS (by 144.8%) schemes. Similarly, the energy consumption of EBSCam is 80.56% and 99.9% less compared with GMM and PBAS, respectively. In summary, the advantages of EBSCam in accuracy, speed, and energy consumption combined together make it especially suitable for embedded applications.
Autors: Muhammad Umar Karim Khan;Asim Khan;Chong-Min Kyung;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jan 2017, volume: 25, issue:1, pages: 35 - 47
Publisher: IEEE
 
» Echo State Networks for Self-Organizing Resource Allocation in LTE-U With Uplink–Downlink Decoupling
Abstract:
Uplink–downlink decoupling in which users can be associated to different base stations in the uplink and downlink of heterogeneous small cell networks (SCNs) has attracted significant attention recently. However, most existing works focus on simple association mechanisms in LTE SCNs that operate only in the licensed band. In contrast, in this paper, the problem of resource allocation with uplink–downlink decoupling is studied for an SCN that incorporates LTE in the unlicensed band. Here, the users can access both licensed and unlicensed bands while being associated to different base stations. This problem is formulated as a noncooperative game that incorporates user association, spectrum allocation, and load balancing. To solve this problem, a distributed algorithm based on the machine learning framework of echo state networks (ESNs) is proposed. This proposed algorithm allows the small base stations to autonomously choose their optimal resource allocation strategies given only limited information on the network’s and users’ states. It is shown that the proposed algorithm converges to a stationary mixed-strategy distribution, which constitutes a mixed strategy Nash equilibrium for their studied game. Simulation results show that the proposed approach yields significant gain, in terms of the sum-rate of the 50th percentile of users, that reaches up to 167% compared with a Q-learning algorithm. The results also show that the ESN significantly provides a considerable reduction of information exchange for the wireless network.
Autors: Mingzhe Chen;Walid Saad;Changchuan Yin;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2017, volume: 16, issue:1, pages: 3 - 16
Publisher: IEEE
 
» Edge Preserving and Noise Reducing Reconstruction for Magnetic Particle Imaging
Abstract:
Magnetic particle imaging (MPI) is an emerging medical imaging modality which is based on the non-linear response of magnetic nanoparticles to an applied magnetic field. It is an important feature of MPI that even fast dynamic processes can be captured for 3D volumes. The high temporal resolution in turn leads to large amounts of data which have to be handled efficiently. But as the system matrix of MPI is non-sparse, the image reconstruction gets computationally demanding. Therefore, currently only basic image reconstruction methods such as Tikhonov regularization are used. However, Tikhonov regularization is known to oversmooth edges in the reconstructed image and to have only a limited noise reducing effect. In this work, we develop an efficient edge preserving and noise reducing reconstruction method for MPI. As regularization model, we propose to use the nonnegative fused lasso model, and we devise a discretization that is adapted to the acquisition geometry of the preclinical MPI scanner considered in this work. We develop a customized solver based on a generalized forward-backward scheme which is particularly suitable for the dense and not well-structured system matrices in MPI. Already a non-optimized prototype implementation processes a 3D volume within a few seconds so that processing several frames per second seems amenable. We demonstrate the improvement in reconstruction quality over the state-of-the-art method in an experimental medical setup for an in-vitro angioplasty of a stenosis.
Autors: Martin Storath;Christina Brandt;Martin Hofmann;Tobias Knopp;Johannes Salamon;Alexander Weber;Andreas Weinmann;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jan 2017, volume: 36, issue:1, pages: 74 - 85
Publisher: IEEE
 
» Edge-Aware Label Propagation for Mobile Facial Enhancement on the Cloud
Abstract:
This paper proposes a facial enhancement framework with mask generation for cloud-based mobile applications. We mathematically analyze and unify the mask generation, as well as the state-of-the-art region-aware mask and edit propagation techniques, from a graph-based semisupervised learning perspective. Then we propose a label propagation model with a new edge-aware structure and guided feature for mask generation. The limit analysis of the model leads to a fast algorithm, which reduces the intrinsic computation cost. Then we develop a flexible and efficient cloud-based PaaS system, called FaceMore, for intelligent mobile face enhancement. The flexibility and extendibility of the cloud-based architecture facilitates intelligent facial enhancement applications and the parallel processing effectively improves the efficiency of the algorithm. Qualitative and quantitative evaluations were performed for mask propagation and face enhancement. Comparisons with the previous methods and five representative commercial systems, including PicTreat, Portraiture, Portrait+, Meitu, and Baidu Motu, illustrate the robustness and effectiveness of our method.
Autors: Lingyu Liang;Lianwen Jin;Deng Liu;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jan 2017, volume: 27, issue:1, pages: 125 - 138
Publisher: IEEE
 
» Editor's Note
Abstract:
Presents the introductory editorial for this issue of the publication.
Autors: David A. Bader;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jan 2017, volume: 28, issue:1, pages: 1 - 1
Publisher: IEEE
 
» Editorial
Abstract:
Presents the editorial for this issue of the publication.
Autors: Jian Pei;Xuemin Lin;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jan 2017, volume: 29, issue:1, pages: 1 - 1
Publisher: IEEE
 
» Effect of Active Layer Thickness on Device Performance of Tungsten-Doped InZnO Thin-Film Transistor
Abstract:
Tungsten ( at. %)-doped InZnO thin-film transistors were fabricated as a function of the active layer thickness using an RF sputtering system. To explain the degradation of the device performance in relation to the changes of the active layer thickness, the correlations between the device performance and the physical properties, including the film density, surface/interface roughness, band edge state below the conduction band, refractive index, and composition along the depth direction were investigated. Tungsten-doped indium–zinc oxide (WIZO) TFTs with active layer thickness of 10 nm exhibited the highest field effect mobility of 19.57 cm2/Vs and the lowest threshold voltage shift of 0.62 V. The enhancement of the device performance is strongly correlated with the highest film density and a flat interface roughness of SiO2–WIZO. In addition, interface layer thickness and band edge states below the conduction band were changed with increasing active layer thickness. These remarkable changes in the interface layer thickness and band edge state could be correlated to changes in the device performance.
Autors: Hyun-Woo Park;Kyung Park;Jang-Yeon Kwon;Dukhyun Choi;Kwun-Bum Chung;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2017, volume: 64, issue:1, pages: 159 - 163
Publisher: IEEE
 
» Effect of Copper Substitution on Fe3O4 Particles Prepared via Coprecipitation and Flux Methods
Abstract:
We investigated the effect of copper substitution on the magnetic and physical properties of Fe3O4 prepared by coprecipitation and flux methods. The coprecipitation compositions were chosen according to the formula (Cux2+Fe1–x2+) Fe23+O4, where varied between 0 and 1. We found that the flux treatment method is ideal for growing large particles of sub-micrometer size. The size of the final particles obtained was in the range of 200–1500 nm, and the size decreased with increasing copper content. Cubic spinel structured CuxFe3–xO4 particles were obtained by conducting hydrogen gas reduction process at 380 °C–530 °C for 1–2 h after flux treatment. From x-ray diffraction patterns, all particles were determined to be cubic spinel without any sign of the tetragonal structure expected from the Jahn–Teller effect. For these cubic spinel particles, saturation magnetization was controlled at 25–86 Am2/kg, and the value decreased linearly with increasing copper content. The coercive force remained almost constant at 13.7–19.1 kA/m, independent of the copper content.
Autors: Hawa Latiff;Mikio Kishimoto;Sonia Sharmin;Eiji Kita;Hideto Yanagihara;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jan 2017, volume: 53, issue:1, pages: 1 - 4
Publisher: IEEE
 
» Effect of Temperature and Stress on Residual Magnetic Signals in Ferromagnetic Structural Steel
Abstract:
Although we know that stress in ferromagnetic steels can induce magnetic signals on the surface, temperature could be another critical factor to impact the signals of the steels used under high temperature conditions. To better understand the mechanism of the residual magnetic signals, a modified Jiles–Atherton (J-A) model based on thermal and mechanical effects was developed. In the experiment, ferromagnetic structural steel Q345B was tested under static tensile stress, and the variation of magnetic signal normal component and its mean value were investigated during the tests. Experimental results showed that the mean value decreased with the increase in temperature, however, increased with the increase in tensile stress. The microstructures were observed at the location of fracture and it was found that the size of inclusions increased with the increase in temperature, which blocked the irreversible movement of magnetic domains and leaded to the decrease of magnetic signals. The experimental results were consistent with the theoretical analysis, which indicated that the variation of effective field calculated based on the modified J-A model was similar to the mean value in the tests.
Autors: Haihong Huang;Zhengchun Qian;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jan 2017, volume: 53, issue:1, pages: 1 - 8
Publisher: IEEE
 
» Effective 3-D Device Electrothermal Simulation Analysis of Influence of Metallization Geometry on Multifinger Power HEMTs Properties
Abstract:
In this brief, obtained results of the electrothermal analysis of multifinger power high-electron mobility transistors (HEMTs) are presented. The analysis of thermal and electrical behavior is supported by effective 3-D electrothermal device simulation method developed for Synopsys TCAD Sentaurus environment using mixed-mode setup. The effects of multifinger HEMT structure metallization layout design are described and studied. Simulation results depict the significant effect of metallization geometry on the electrothermal properties and behavior of the power multifinger HEMTs.
Autors: Aleš Chvála;Juraj Marek;Patrik Príbytný;Alexander Šatka;Martin Donoval;Daniel Donoval;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2017, volume: 64, issue:1, pages: 333 - 336
Publisher: IEEE
 
» Effects of MgxZn1-xO Thickness on the Bandwidth of Metal–Semiconductor–Metal Bandpass Photodetectors
Abstract:
A metal–semiconductor–metal photodetector (PD) whose detection wavelength can be modulated was fabricated using a MgxZn1-xO/ZnO bilayer. By varying the MgxZn1-xO layer thickness (50–400 nm), we modulated the detection wavelength from lowpass to bandpass. For a thin (50 nm) MgxZn1-xO film, most short-wavelength (less than 340 nm) incident photons—more than 69%—passed through the MgxZn1-xO and were absorbed by ZnO, causing a higher photoresponse in the short-wavelength region and thus a low-pass PD. As the thickness of the MgxZn1-xO film increased, the short-wavelength photoresponse was gradually suppressed, and a bandpass PD was achieved. A thicker (400 nm) MgxZn1-xO film absorbed more short-wavelength (less than 340 nm) incident photons, leaving only 5.5% of the incident photons to be absorbed by the ZnO layer underneath. This reduced the short-wavelength photoresponse, yielding a bandpass PD with a detection wavelength of 325–360 nm. Although the short-wavelength (less than 340 nm) incident photons were absorbed by MgxZn1-xO, few photogenerated electron–hole pairs contributed to the photoresponse; instead, they were trapped by the defects in MgxZn1-xO because of its poor crystalline quality.
Autors: Jun-Dar Hwang;Guan-Syun Lin;Sheng-Beng Hwang;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2017, volume: 64, issue:1, pages: 195 - 199
Publisher: IEEE
 
» Effects of Nonuniform Magnetic Fields on the “Magnetic Window” in Blackout Mitigation
Abstract:
The “magnetic window” is considered a promising means to eliminate reentry communications blackout. Nevertheless, a numerical analysis is needed detailing the efficacy of the window under nonuniform magnetic fields generated by a magnet. For this purpose, the electromagnetic wave transmission characteristics are obtained using the hybrid matrix method. A two-Gaussian model for the plasma sheath density is assumed. The sheath is modeled by partitioning into slabs, for which the magnetic field and electron density in each slab are assumed uniform. Various plasma parameter values and magnetic field strengths are used. The numerical results show that, compared with uniform magnetic fields, a wider stopband in the transmission response is formed using nonuniform magnetic fields; the stopband width depends on the range between the maximum and the minimum magnetic field strengths. Therefore, the frequency hoped for in the magnetic window in the left passband using uniform magnetic field may be located in the stopband arising from the nonuniform magnetic field.
Autors: Hui Zhou;Xiaoping Li;Yanming Liu;Bowen Bai;Kai Xie;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jan 2017, volume: 45, issue:1, pages: 15 - 23
Publisher: IEEE
 
» Efficiency and Stability of Pulse Compression Using SBS in a Fiber With Frequency-Shifted Loopback
Abstract:
Efficient pulse compression using stimulated Brillouin scattering in a fiber is proposed where the pump pulse transmitted through the fiber is immediately loopbacked to the fiber with its frequency downshifted by the amount equal to the Brillouin frequency shift of the fiber. The effect of the steepness of the front edge of the pump pulse on the compression performance and the influence of the spontaneous Brillouin scattering on the stability of the compressed pulses are numerically studied. A preliminary experiment of the proposed scheme is also reported.
Autors: Masayuki Matsumoto;Genya Miyashita;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2017, volume: 29, issue:1, pages: 3 - 6
Publisher: IEEE
 
» Efficient and Precise Dynamic Initialization of Induction Motors Using Unified Newton–Raphson Power-Flow Approach
Abstract:
An accurate initialization is very important for power-system dynamic simulations. Using conventional power-flow model to initialize induction motors is not straightforward because an unavoidable mismatch between pre-specified reactive powers from power-flow calculation and the ones, actually required by motors. To overcome this problem, this paper presents a unified method for incorporating a nonlinear model of induction motors into Newton–Raphson (NR) power-flow algorithm, allowing precise steady-state solutions of power networks with induction motors to be solved simultaneously. The power-flow results of the extended algorithm are then compared with benchmark results for model verification. The ability of the extended algorithm is also demonstrated using IEEE-30 bus and 118 bus test systems with large groups of induction motor loads. The studied results indicate that the presented algorithm not only gives exact steady-state initialization without existence of the reactive power mismatches but also preserves powerful Newton–Raphson's quadratic convergence characteristics.
Autors: P. Aree;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jan 2017, volume: 32, issue:1, pages: 464 - 473
Publisher: IEEE
 
» Efficient Channel Estimation for Reconfigurable MIMO Antennas: Training Techniques and Performance Analysis
Abstract:
Multifunctional and reconfigurable multiple-input multiple-output (MR-MIMO) antennas are capable of dynamically changing the operation frequencies, polarizations, and radiation patterns, and can remarkably enhance system capabilities. However, in coherent communication systems, using MR-MIMO antennas with a large number of operational modes may incur prohibitive complexity due to the need for channel state estimation for each mode. To address this issue, we derive an explicit relation among the radiation patterns for the antenna modes and the resulting channel gains. We propose a joint channel estimation/prediction scheme where only a subset of all the antenna modes is trained for estimation, and then, the channels associated with the modes that are not trained are predicted using the correlations among the different antenna modes. We propose various training mechanisms with reduced overhead and improved estimation performance, and study the impact of channel estimation error and training overhead on the MR-MIMO system performance. We demonstrate that one can achieve significantly improved data rates and lower error probabilities utilizing the proposed approaches. For instance, under practical settings, we observe about 25% throughput increase or about 3-dB signal-to-noise ratio improvement under the same training overhead with respect to non-reconfigurable antenna systems.
Autors: Israfil Bahceci;Mehedi Hasan;Tolga M. Duman;Bedri A. Cetiner;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2017, volume: 16, issue:1, pages: 565 - 580
Publisher: IEEE
 
» Efficient Designs of Multiported Memory on FPGA
Abstract:
The utilization of block RAMs (BRAMs) is a critical performance factor for multiported memory designs on field-programmable gate arrays (FPGAs). Not only does the excessive demand on BRAMs block the usage of BRAMs from other parts of a design, but the complex routing between BRAMs and logic also limits the operating frequency. This paper first introduces a brand new perspective and a more efficient way of using a conventional two reads one write (2R1W) memory as a 2R1W/4R memory. By exploiting the 2R1W/4R as the building block, this paper introduces a hierarchical design of 4R1W memory that requires 25% fewer BRAMs than the previous approach of duplicating the 2R1W module. Memories with more read/write ports can be extended from the proposed 2R1W/4R memory and the hierarchical 4R1W memory. Compared with previous xor-based and live value table-based approaches, the proposed designs can, respectively, reduce up to 53% and 69% of BRAM usage for 4R2W memory designs with 8K-depth. For complex multiported designs, the proposed BRAM-efficient approaches can achieve higher clock frequencies by alleviating the complex routing in an FPGA. For 4R3W memory with 8K-depth, the proposed design can save 53% of BRAMs and enhance the operating frequency by 20%.
Autors: Bo-Cheng Charles Lai;Jiun-Liang Lin;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jan 2017, volume: 25, issue:1, pages: 139 - 150
Publisher: IEEE
 
» Efficient Feasibility Determination With Multiple Performance Measure Constraints
Abstract:
Feasibility determination has emerged as a widely applied problem in simulation optimization. It seeks to provide all the feasible designs from a finite set of design alternatives based on which the final decision can be chosen by the decision maker. In this paper, we consider the feasibility determination problem in presence of multiple performance measure constraints. The optimal solution to maximize the probability of correct feasibility determination is derived under asymptotic approximation. A corresponding sequential selection procedure is designed for implementation. The numerical testing shows that our approach can enhance the simulation efficiency significantly.
Autors: Siyang Gao;Weiwei Chen;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jan 2017, volume: 62, issue:1, pages: 113 - 122
Publisher: IEEE
 
» Efficient Sensitivity Analysis for Inequality Queries in Probabilistic Databases
Abstract:
In this paper, we study inequality query (IQ query) processing in tuple independent probabilistic databases, where IQ queries can be categorized into IQ-path, IQ-tree, and IQ-graph queries. We focus on two related issues for IQ queries. One issue is to efficiently compute their probabilities, with the observation that the time complexity of the state-of-the-art algorithm to process IQ-graph queries is high. The other issue is to efficiently perform their sensitivity analysis, which has not been studied before. Here, sensitivity analysis is to identify input tuples that have high influence on the probability of an answer tuple, and the influence of an input tuple is defined as the difference between the output probabilities obtained in two cases, where we assume that the tuple exists in one case and does not exist in the other one. In this paper, we compile the inequality conditions of an IQ query into a compilation tree , which encodes the Shannon expansion order. Moreover, we split into a set of subqueries and each contains only one inequality condition. Using compilation tree and decomposition, we introduce a dynamic programming algorithm called to process an IQ query in time O(|\Phi |) , where is the lineage of . An IQ query can be processed by our if and only if its inequality conditions can be compiled into a compilation tree and the inequality conditions from any node to all of its child nodes must be the same in . We conduct extensive experiments using real and synthetic datasets to demonstrate the efficiency of our algorithm for computing the probabilities and influences of IQ queries.
Autors: Biao Qin;Jeffrey Xu Yu;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jan 2017, volume: 29, issue:1, pages: 86 - 99
Publisher: IEEE
 

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