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2012 Symposium on VLSI technology, VLSIT 2012

作者： Chen, Xiangyu Seo, David H. Seo, Sunae Chung, Hyunjong Wong, H.-S. Philip Dept. of Electrical Engineering Center for Integrated Systems Stanford University Stanford CA 94305 United States Semiconductor Devices Laboratory Samsung Advanced Institute of Technology Yongin 446-712 Korea Republic of Dept. of Physics Sejong University Seoul 143-747 Korea Republic of

ISBN: (纸本)9781467308458

Lifetime of multi-layer graphene interconnects under constant current stress is studied for the first time. Under a stress current density of 20MA/cm2 at 250°C exposed to air, Mean-Time-To-Fail (MTTF) of uncapped CVD graphene wire is about 6 hours. It is shown that lifetime is mainly limited by defect formation due to graphene oxidation. © 2012 IEEE.

关键词： Graphene

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Temperature Distribution in a Disc-Type Transformer Winding

Temperature Distribution in a Disc-Type Transformer Winding

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IEEE Conference on Industrial Electronics and Applications

作者： Jaury Wijaya Wenyu Guo Tadeusz Czaszejko Daniel Martin Nick Lelekakis Dejan Susa Dept. of Electrical & Computer Systems Engineering Monash University Electric Power Technology SINTEF Energy Research

ISBN: (纸本)9781457721182

The winding hot-spot temperature is an extremely important factor limiting the loading capability of a power transformer. High temperature also accelerates the aging of paper insulation and thus reduces the lifetime of a transformer. Ohmic losses in the winding are the main source of heat inside a transformer. Precise knowledge of these losses is very important to determine the winding temperature distribution. Furthermore, in an oil-immersed power transformer, oil is used both as insulation and as liquid coolant In a disc-type winding, a non-uniform coolant flow, in horizontal ducts, can contribute to local overheating. This article describes a new approach to estimate the winding temperature distribution, in which losses are computed by the finite element method whereas the coolant circulation and the temperature distribution are obtained from a thermal-hydraulic network representation of the winding.

关键词： Power transformers Winding temperature Temperature distribution Eddy losses FEM COMSOL Thermal-hydraulic network

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Filter design oriented EMI prediction model for DC-fed motor drive system using double fourier integral transformation method

Filter design oriented EMI prediction model for DC-fed motor...

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International Conference on Power Electronics and Motion Control (IPEMC)

作者： Xuning Zhang Dushan Boroyevich Paolo Mattavelli Fred Wang The Bradley Dept. of Electrical & Computer Engineering Virginia Tech Center for Power Electronics Systems (CPES) Blacksburg VA Dept. of Electrical Engineering & Computer Science University of Tennessee Knoxville Knoxville TN US

This work proposes a frequency-domain EMI prediction model for common mode (CM) and differential mode (DM) noises for the purpose of designing EMI filters before the system construction. The parameters in the model can be extracted from system detail switching model or measured from the real system. The Double Fourier Integral Transformation (DFIT) method is used to calculate the noise sources in the model. When the system topology modulation method and modulation index is fixed, the system EMI noise can be predicted from the calculation of the equivalent model. Verifications are carried out through simulation and experiment system by comparing the calculated EMI spectrums and simulated and measured EMI spectrums. Based on the proposed model, this paper also proves that the resonances in EMI noise propagation path will have a significant impact on the EMI filter design for DC fed motor drive system with long cables.

关键词： Noise Electromagnetic interference Impedance Delta modulation Predictive models Motor drives Noise measurement

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Formal Abstraction of Linear systems via Polyhedral Lyapunov Functions *

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IFAC Proceedings Volumes 2012年第9期45卷 88-93页

作者： Xuchu Ding Mircea Lazar Calin Belta Dept. of Systems at United Technologies Research Center East Hartford CT 06108 USA Dept. of Electrical Engineering at Eindhoven University of Technology Eindhoven The Netherlands Dept. of Mechanical Engineering at Boston University Brookline MA 02446 USA

In this paper we present an abstraction algorithm that produces a finite bisimulation quotient for an autonomous discrete-time linear system. We assume that the bisimulation quotient is required to preserve the observations over an arbitrary, finite number of polytopic subsets of the system state space. We generate the bisimulation quotient with the aid of a sequence of contractive polytopic sublevel sets obtained via a polyhedral Lyapunov function. The proposed algorithm guarantees that at iteration i, the bisimulation of the system within the i -th sublevel set of the Lyapunov function is completed. We then show how to use the obtained bisimulation quotient to verify the system with respect to arbitrary Linear Temporal Logic formulas over the observed regions.

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Performance of single-and dual-color detectors using InAs/GaSb strained layer superlattices

Performance of single-and dual-color detectors using InAs/Ga...

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IEEE Conference on High Performance Devices

作者： E. Plis N. Gautam B. Klein S. Myers T. Schuler-Sandy M. N. Kutty Z.-B. Tian S. Krishna Dept. of Electrical and Computer Engineering University of New Mexico Center for High Technology Materials Albuquerque USA

We report on a heterojunction band gap engineered single- and dual-color photodetectors with pBiBn and pBp architecture, respectively. The detailed optical and electrical characterization of these devices has been performed. The pBiBn detector demonstrated a specific detectivity of 3 × 10 10 Jones at 8m wavelength and a specific detectivity of 5 × 10 11 Jones and 2.6 × 10 10 Jones for MWIR (at 5 μm) and LWIR (9 μm) absorbers, respectively, has been measured for dual-band pBp detector. Observed performance of unipolar barrier devices is superior to the performance of homojunction single-and dual-color detectors based on the same material system and operating at the same wavelength range.

关键词： Detectors Wavelength measurement Dual band Performance evaluation Photonic band gap Dark current Superlattices

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Priority Handling Aggregation Technique (PHAT) for Wireless Sensor Networks

Priority Handling Aggregation Technique (PHAT) for Wireless ...

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International Conference on Emerging Technologies and Factory Automation (ETFA)

作者： Dimitris Tsitsipis Sofia Maria Dima Angeliki Kritikakou Christos Panagiotou John Gialelis Harris Michail Stavros Koubias Dept. of electrical and Computer Engineering University of Patras Patras Greece Industrial Systems Institute/RC Athena Stadiou str Platani Patras Greece Dept. of electrical Engineering and Information Technology Cyprus University of Technology

Wireless Sensor Networks (WSNs) have limited power capabilities, whereas they serve applications which usually require specific packets, i.e. High Priority Packets (HPP), to be delivered before a deadline. Hence, it is essential to reduce the energy consumption and to have real-time behavior. To achieve this goal we propose a hybrid technique which explores the benefits of data aggregation without data size reduction in combination with prioritized queues. The energy consumption is reduced by appending data from incoming packets with already buffered Low Priority Packets (LPP). The real-time behavior is achieved by directly forwarding the HPP to the next node. Our study explores the impact of the proposed hybrid technique in several all-to-one data flow scenarios with various traffic loads, wait time intervals and percentage of HPP. Our results show gain up to 23,3% in packet loss and 36,6% in energy consumption compared with the direct forwarding of packets.

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Time-domain preamble-based SNR estimation for OFDM systems in doubly selective channels

Time-domain preamble-based SNR estimation for OFDM systems i...

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2012 IEEE Military Communications Conference, MILCOM 2012

作者： Yang, Fan Zhang, Xi Zhang, Zhong-Pei School of Communication and Information Engineering University of Electronic Science and Technology of China Chengdu 611731 China Networking and Information Systems Laboratory Dept. of Electrical and Computer Engineering Texas A and M University College Station TX 77843 United States National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of China Chengdu 611731 China

ISBN: (纸本)9781467317290

In wireless orthogonal frequency division multiplexing (OFDM) systems, the knowledge of signal-to-noise ratio (SNR) plays an important role for system optimization. Most of the exiting literatures have studied the SNR estimation for perfect synchronization in additive white Gaussian noise (AWGN) channels, or in frequency selective channels. However, the realistic channels are always doubly selective, and there may exist some residual symbol timing offset (STO) and carrier frequency offset (CFO) after coarse synchronization in the time domain. In this paper, we take these into account and propose a time-domain average SNR estimation scheme using one OFDM training symbol (preamble) which has been divided into multiple parts with equal length. Compared with the timedomain low-complexity SNR estimator (TLSE), our proposed time-domain preamble-based SNR estimator (TPSE) can not only be implemented in the presence of STO and CFO, but also generate more accurate SNR estimation for the channels with large Doppler shift. The estimated SNR value based on our scheme in the time-domain can be further reused to improve the ensuing CFO estimation and fine synchronization efficiently. © 2012 IEEE.

关键词： Orthogonal frequency division multiplexing

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A Tutorial of Wind Turbine Control for Supporting Grid Frequency through Active Power Control

A Tutorial of Wind Turbine Control for Supporting Grid Frequ...

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American Control Conference

作者： Jacob Aho Andrew Buckspan Jason Laks Paul Fleming Yunho Jeong Fiona Dunne Matthew Churchfield Lucy Pao Kathryn Johnson Dept. of Electrical Computer and Energy Engineering University of Colorado Boulder National Wind Technology Center Boulder Division of Engineering Colorado School of Mines Golden Colorado School of Mines Dept. of Electrical Engineering and Computer Science

ISBN: (纸本)9781457710957

As wind energy becomes a larger portion of the world's energy portfolio and wind turbines become larger and more expensive, wind turbine control systems play an ever more prominent role in the design and deployment of wind turbines. The goals of traditional wind turbine control systems are maximizing energy production while protecting the wind turbine components. As more wind generation is installed there is an increasing interest in wind turbines actively controlling their power output in order to meet power set-points and to participate in frequency regulation for the utility grid. This capability will be beneficial for grid operators, as it seems possible that wind turbines can be more effective at providing some of these services than traditional power plants. Furthermore, establishing an ancillary market for such regulation can be beneficial for wind plant owner/operators and manufacturers that provide such services. In this tutorial paper we provide an overview of basic wind turbine control systems and highlight recent industry trends and research in wind turbine control systems for grid integration and frequency stability.

关键词： Wind turbines Generators Blades Wind energy Rotors Frequency control Torque

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On the Capacity of Underwater Acoustic Particle Velocity Communication Channels

On the Capacity of Underwater Acoustic Particle Velocity Com...

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OCEANS Conference

作者： Huaihai Guo Ali Abdi Center for Wireless Communication and Signal Processing Research Dept. of Electrical and Computer Engineering New Jersey Institute of Technology

ISBN: (纸本)9781467308298

In this paper, the capacity of acoustic particle velocity channels is investigated. Closed form expressions are derived that determine maximum data rates in particle velocity channels, in terms of mean angle of arrival and angle spread. These expressions are useful for designing communication systems that operate in particle velocity channels.

关键词： Channel capacity Orthogonal frequency division multiplexing Particle velocity channels Underwater communication Vector sensors

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LIDAR wind speed measurements of evolving wind fields 50

LIDAR wind speed measurements of evolving wind fields

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50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

作者： Simley, Eric Pao, Lucy Y. Kelley, Neil Jonkman, Bonnie Frehlich, Rod Dept. of Electrical Computer and Energy Engineering University of Colorado Boulder CO United States National Wind Technology Center NREL Golden CO 80401 United States Cooperative Institute for Research in Environmental Sciences Boulder CO 80309 United States

ISBN: (数字)9781600869365

Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed Taylor's frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations to create a more realistic measurement model. A simple model of wind evolution is applied to a frozen wind field used in previous studies to investigate the effects of varying the intensity of wind evolution. Simulation results show the combined effects of LIDAR errors and wind evolution for realistic turbine-mounted LIDAR measurement scenarios. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Wind

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