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Polyphase Filter Banks for Embedded Sample Rate Changes in Digital Radio Front-Ends

ZTE Communications 2011年第4期9卷 3-9页

作者： Mehmood Awan Yannick Le Moullec Peter Koch Fred Harris Technology Platforms Section Dept. of Electronic Systems Aalborg University Denmark Dept. of Electrical & Computer Engineering San Diego State UniversityCA USA

This paper presents efficient processing engines for software-defined radio （SDR） front-ends. These engines, based on a polyphase channelizer, perform arbitrary sample-rate changes, frequency selection, and bandwidth control. This paper presents an M-path polyphase filter bank based on a modified N-path polyphase filter. Such a system allows resampling by arbitrary ratios while performing baseband aliasing from center frequencies at Nyquist zones that are not multiples of the output sample rate. This resampling technique is based on sliding cyclic data load interacting with cyclic-shifted coefficients. A non-maximally-decimated polyphase filterbank （where the number of data loads is not equal to the number of M subfilters） processes M subfilters in a time period that is less than or greater than the M data loads. A polyphase filter bank with five different resampling modes is used as a case study for embedded resamp/ing in SDR front-ends. These modes are （i） maximally decimated, （ii） Under-decimated, （iii） over-decimated, and combined up- and down-sampling with （iv） single stride length, and （v） multiple stride lengths. These modes can be used to obtain any required rational sampling rate change in an SDR front-end based on a polyphase channelizer. They can also be used for translation to and from arbitrary center frequencies that are unrelated to the output sample rates.

关键词： SDR digital front-ends polyphase filter bank embedded resampling

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Titanium dioxide nanotubes decorated with nanoparticles for dye sensitized solar cells

Titanium dioxide nanotubes decorated with nanoparticles for ...

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2010 MRS Fall Meeting

作者： Pan, Xuan Zhao, Yong Chen, Changhong Fan, Zhaoyang Nano Tech. Center Dept. of Electrical and Computer Engineering Texas Tech University Lubbock TX United States Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781605112800

The titanium dioxide (TiO2) nanoparticle (NP) structure has higher surface area and dye loading value to increase photon absorption while the nanotube (NT) can suppress the random walk phenomena to enhance carrier collection. In this work, hydrothermal method was utilized to infiltrate the TiO2 nanotube array by TiO2 nanoparticles with the aim of combining the advantages of both nanostructures to improve dye sensitized solar cells (DSSCs) efficiency. Structure morphology, device performance, and electrochemical properties were investigated. SEM observation confirmed that around 10 nm TiO2 nanoparticles uniformly covered the NT wall. TiO2 NT samples at three different lengths: 8 μm, 13 μm and 20 μm, decorated with different amount of nanoparticles were studied to optimize the structure for light absorption and electron transport to achieve high solar conversion efficiency. Electrochemical impedance spectroscopy (EIS) was also employed to investigate the cells' parameters: electron lifetime (τ), diffusion length (Ln) et al, to gain insight on the device performance. The incident photon conversion efficiency (IPCE) was also reported. © 2011 Materials Research Society.

关键词： Titanium dioxide

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Adapting an Object Detector by Considering the Worst Case: a Conservative Approach

Adapting an Object Detector by Considering the Worst Case: a...

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IEEE Conference on computer Vision and Pattern Recognition

作者： Guang Chen Tony X. Han Shihong Lao Electrical and Computer Engineering Dept. University of Missouri Core Technology Center Omron Corporation

ISBN: (纸本)9781457703942

The performance of an offline-trained classifier can be improved on-site by adapting the classifier towards newly acquired data. However, the adaptation rate is a tuning parameter affecting the performance gain substantially. Poor selection of the adaptation rate may worsen the performance of the original classifier. To solve this problem, we propose a conservative model adaptation method by considering the worst case during the adaptation process. We first construct a random cover of the set of the adaptation data from its partition. For each element in the cover (i.e. a portion of the whole adaptation data set), we define the cross-entropy error function in the form of logistic regression. The element in the cover with the maximum cross-entropy error corresponds to the worst case in the adaptation. Therefore we can convert the conservative model adaptation into the classic min-max optimization problem: finding the adaptation parameters that minimize the maximum of the cross-entropy errors of the cover. Taking the object detection as a testbed, we implement an adapted object detector based on binary classification. Under different adaptation scenarios and different datasets including PASCAL, ImageNet, INRIA, and TUD-Pedestrian, the proposed adaption method achieves significant performance gain and is compared favorably with the state-of-the-art adaptation method with the fine tuned adaptation rate. Without the need of tuning the adaptation rates, the proposed conservative model adaptation method can be extended to other adaptive classification tasks.

关键词： Conservative Object detection Classifiers

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Multi-agent based simulation for Microgrid energy management

Multi-agent based simulation for Microgrid energy management

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8th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2011-ECCE Asia

作者： Meiqin, Mao Wei, Dong Chang, Liuchen Research Center for Photovoltaic System Engineering MOE PRC Hefei University of Technology Hefei 230009 China Dept. of Electrical and Computer Engineering University of New Brunswick Fredericton NB E3B 5A3 Canada

ISBN: (纸本)9781612849560

This paper presents a general multi-agent based model for the hierarchical and distributed energy control of a Microgrid. In this model, the agents under three different levels are classified and defined in detail. And based on the model, a novel simulation platform for the energy management system of the Microgrid (EMS-MG) is designed in terms of Client-Server and implemented under C Builder environment. Taking the generation automatic control for example and by the proposed model and implemented EMS-MG, a simulation result is shown to illustrate the operation process of the simulation platform and present the benefits of the proposed method. © 2011 IEEE.

关键词： Energy management

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An Evaluation of Operating Reserve using Distributed Generators as an Alternative for Thermal Power Plants

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Journal of International Council on electrical engineering 2011年第3期1卷 317-322页

作者： Shinsuke Tsujita Takao Shinji Tsutomu Oyama Smart Energy Technology Center Tokyo Gas Co. Ltd Dept. of Electrical and Computer Engineering Faculty of Engineering Yokohama National University

Electric power systems, which include many renewable energy resources for worldwide low-carbon path, have a lot of problems and many studies are made for its solutions. Co-generation systems which consist of gas engine etc. have also been expected to make low-carbon path come true. One of difference between gas engines and renewable energy resources is their controllability. In this study, the operating reserve is considered as the ancillary service from distributed generator side. We have considered whether distributed generators are able to alternative thermal power plant when the peak demands. As the result, we have realized the generating cost of distributed generator possible to able to reduce against existing thermal power plant.

关键词： Distributed generator Ancillary service Economic load dispatching Microgrid Smart energy network

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Investigation of tradeoffs between efficiency, power density and switching frequency in three-phase two-level PWM boost rectifier

Investigation of tradeoffs between efficiency, power density...

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European Conference on Power Electronics and Applications

作者： Bo Wen Dushan Boroyevich Paolo Mattavelli The Bradley Dept. of Electrical and Computer Engineering Center for Power Electronics Systems Blacksburg VA United Sated

ISBN: (纸本)9781612841670

Efficiency and power density are usually two important goals regarding power converter design. The focus of this paper is to develop an evaluation procedure to investigate the relationship between efficiency, power density and switching frequency. Three-phase two-level PWM boost rectifier is used as an example. Estimated efficiency and converter weight changing along with switching frequency and power rating are shown. A comparison with a hardware prototype is carried out to verify the estimation procedure.

关键词： Insulated gate bipolar transistors Thermal resistance Heat sinks Switching frequency Rectifiers

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Modularized Design Consideration of a General-Purpose, High-Speed Phase-Leg PEBB Based on SiC MOSFETs

Modularized Design Consideration of a General-Purpose, High-...

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CPES Annual Power Electronics Conference

作者： Zheng Chen Milisav Danilovic Dushan Boroyevich Zhiyu Shen CENTER FOR POWER ELECTRONICS SYSTEMS (CPES) The Bradley Dept. of Electrical and Computer Engineering Virginia Polytechnic Institute and State University

ISBN: (纸本)9781612841670

This paper presents the modularized design and analysis of a phase-leg module based on the Power Electronics Building Block (PEBB) concept. 1200 V SiC MOSFETs and Schottky diodes are used as the main switches for the phase-leg to be used in 600 to 800 V, medium-power converters. The design aims at generalizing the module for various circuit topologies through smart control scheme, while the device switching speed is also pushed to the limit through optimized gate driver and circuit layout designs in order to achieve the high-frequency operation capability of the PEBB.

关键词： Device application Silicon Carbide (SiC) MOSFET High frequency power converter design consideration PEBB SILICON CARBIDE Power electronics Modularity master switches SUB-SYSTEM

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Analysis of wind speed measurements using continuous wave LIDAR for wind turbine control

Analysis of wind speed measurements using continuous wave LI...

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49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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

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 accurate the incoming wind field can be measured. This study examines the accuracy of different measurement scenarios that rely on coherent continuous- wave Doppler LIDAR systems to determine their applicability to feedforward control. In particular, the impacts of measurement range and angular offset from the wind direction are studied for various wind conditions. A realistic case involving a scanning LIDAR unit mounted in the spinner of a wind turbine is studied in dept., with emphasis on choices for scan radius and preview distance. The effects of turbulence parameters on measurement accuracy are studied as well. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Wind turbines

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Fractional Gain Scheduled Controller for a Networked Smart Wheel: Experimental Results

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IFAC Proceedings Volumes 2011年第1期44卷 15043-15048页

作者： Inés Tejado Blas M. Vinagre YangQuan Chen Industrial Engineering School University of Extremadura 06006 Badajoz Spain Center for Self-Organizing and Intelligent Systems Dept. of Electrical and Computer Engineering Utah State University 84322 Logan UT USA

Abstract The performance of Networked Control systems (NCS) is directly affected mainly by time-varying network delays, so a specific approach to compensate their effects is usually required during the controller design process. This paper deals with the control of an experimental platform over the Internet by applying a novel fractional gain scheduling strategy which enables an existing fractional order PI controller for efficient control over the network. The proposed controller introduces delay-adaptive gains, which are optimal with respect to the current network condition. Experimental results show the effectiveness of the proposed controller, providing significantly better system performance, especially when the network-induced delay is increased in certain circumstances.

关键词： Networked control system Gain scheduling Variable delay Fractional order PI controller SmartWheel NCS testbed

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High-Rate Deposited Amorphous Silicon Nitride for the Hydrogenated Amorphous Silicon Thin-Film Transistor Structures

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MRS Online Proceedings Library 2011年第1期424卷 43-51页

作者： Tong Li Chun-ying Chen Charles T. Malone Jerzy Kanicki Dept of Electrical Engineering and Computer Science Center for Display Technology and Manufacturing The University of Michigan Ann Arbor USA Optical Imaging Systems Inc. Northville USA

Hydrogenated amorphous silicon nitride thin films, prepared in a large area plasma-enhanced chemical vapor (PECVD) deposition system utilizing high-rate deposition technique, have been characterized by various techniques. Experimental data obtained from this study are presented and compared to low-rate deposited PECVD films. Special attention has been devoted during this study to the difference between high- and low-rate deposited samples. The amorphous silicon (a-Si:H) thin-film transistors (TFTs) based on high-rate PECVD materials have been fabricated and characterized. The evaluation of a-Si:H TFTs indicates a good electrical performance which is comparable to its low-rate PECVD materials counterparts.

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