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A novel thermal management system for electric vehicle batteries using phase-change material

JOURNAL OF THE ELECTROCHEMICAL SOCIETY 2000年第9期147卷 3231-3236页

作者： Al Hallaj, S Selman, JR IIT Dept Environm Chem & Engn Ctr Electrochem Sci & Engn Chicago IL 60616 USA

A novel thermal-management system that incorporates phase-change material (PCM) is proposed and investigated for electric vehicle (EV) applications. A commercial finite-element (FE) software, PDEase2D(TM), was used to simulate the thermal behavior of EV battery modules with a PCM thermal management system. Simulation results show that the temperature profile of the cells integrated in the module design was substantially more uniform during discharge at different rates than without PCM. The PCM system is effective in thermally sensitive batteries such as Li-ion and most Li-polymer batteries with a significant reversible heat effect. The heat generated during discharge and stored as latent heat is then largely utilized during charge, and a smaller part of it is transferred to the surroundings. The stored heat will be rejected to the module when the battery is left to relax or when its temperature drops below the melting point of the PCM. This is an important advantage for EV operation under cold conditions or in space applications where the battery temperature drops significantly when an orbiting satellite moves from the light to the dark side of the earth. (C) 2000 The Electrochemical Society. S0013-4651(00)01-030-2. All rights reserved.

关键词： Phase change materials Effect of heat temperature profiles Electric vehicles Small parts Dismissal Space applications lithium ion battery discharge discharge pulse code modulation Thermal management Batteries

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Analysis of Complexity of PCM Chaotic code in Changeable Order Hyperchaotic Circuit System

Analysis of Complexity of PCM Chaotic Code in Changeable Ord...

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2000年第16届世界计算机大会

作者： Lin Zi Li Kuijun Xu Yong Changchun Post Institute and Telecommunication Department of Communication Engineering

This paper mainly analyzes the complexity of PCM chaotic code by means of time sequence method on a changeable order hyperchaotic circuit *** the computer-based simulation results and the experimental circuit results arc *** comparing complexity of chaotic system with that of hyperchaotic system,we draw a conclusion that their theoretical results is in accordance with experimental one.

关键词： Chaos pulse code modulation complexity Lyapunov exponent symbolic dynamics

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Application of sub-band ADPCM for post-production and broadcast audio

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SMPTE JOURNAL 1999年第10期108卷 724-727页

作者： Knapton, J Audio Proc Technol Ltd Belfast BT2 9JQ Antrim North Ireland

Digital program delivery is becoming a reality. It offers more programs, a higher definition picture, and an enhanced audio experience. To serve this market, contribution and distribution systems in the broadcast and post-production industries must move rapidly to provide the digital infrastructure to cope with this evolution. This poses many questions: In terms of financial, technological, and bandwidth constraints, how can one sustain a quality multichannel audio signal through a typical broadcast chain, allowing for interim signal processing requirements. This paper proposes the use of the apt-X algorithm (proprietary encode/decode algorithm for digital audio data compression) as an ideal mezzanine level audio coding system for use in conjunction with digital audio broadcasting (DAB) and digital television (DTV) emission standards. This preserves the audio quality throughout the broadcast chain and alleviates production problems arising from psychoacoustic artifacts.

关键词： pulse code modulation

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Investigation of enhanced CO tolerance in proton exchange membrane fuel cells by carbon supported PtMo alloy catalyst

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ELECTROCHEMICAL AND SOLID STATE LETTERS 1999年第1期2卷 12-15页

作者： Mukerjee, S Lee, SJ Ticianelli, EA McBreen, J Grgur, BN Markovic, NM Ross, PN Giallombardo, JR De Castro, ES Brookhaven Natl Lab Dept Appl Sci Upton NY 11973 USA Univ Calif Berkeley Lawrence Berkeley Lab Div Mat Sci Berkeley CA 94720 USA ETEK Inc Natick MA 01760 USA

We report a two- to threefold enhancement of CO tolerance in a proton exchange membrane (PEM) fuel cell, exhibited by carbon supported nanocrystalline PtMo/C as compared to the current state of the art PtRu/C electrocatalysts. The bulk of these nanocrystals were comprised of Pt alloyed with Mo in the ratio 8.7: 1.3 as shown by both X-ray diffraction and in situ extended X-ray absorption fine structure measurements. Rotating disk electrode measurements and cyclic voltammetry in a PEM fuel cell indicate the onset of CO oxidation at potentials as low as 0.1 V. Further, the oxidation of CO exhibits two distinct peaks, indicating redox behavior involving oxyhydroxides of Mo. This is supported by in situ X-ray absorption near edge structure measurements at the Mo K edge. (C) 1999 The Electrochemical Society. S1099-0062(98) 08-029-8. All rights reserved.

关键词： X-ray absorption Proton exchange membrane fuel cells Nanocrystals pulse code modulation current status

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Oversampling and sigma-delta strategies for data conversion

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ELECTRONICS & COMMUNICATION ENGINEERING JOURNAL 1998年第1期10卷 37-47页

作者： Stewart, RW Pfann, E Univ Strathclyde Dept Elect & Elect Engn Signal Proc Div Glasgow G1 1XW Lanark Scotland

This paper presents an introduction to oversampling techniques a nd the theory and advantages of sigma-delta (Sigma Delta) devices for digital-to-analogue conversion (DAC) and analogue-to-digital conversion (ADC) in digital signal processing (DSP) systems. It begins with a discussion of conventional Nyquist-sampling-rate DSP, which is followed by an overview of oversampling and decimation/interpolation techniques to reduce the anti-alias and reconstruction filter specifications. Oversampling strategies to increase the resolution of an N-bit ADC or DAC by reducing the baseband quantisation noise are then presented, and this is followed by a description of the use of Sigma Delta noise-shaping techniques and the design of Sigma Delta converters. The paper concludes with comments on a few of the application and research areas where Sigma Delta devices are having a major impact.

关键词： digital signal processing pulse code modulation PCM systems data conversion Nyquist-sampling-rate DSP Digital signal processing chips sigma-delta strategies quantisation (signal) digital-to-analogue conversion Digital signal processing digital signal processing chips Interpolation and function approximation (numerical analysis) modulation and coding methods baseband quantisation noise filtering theory decimation/interpolation oversampling techniques signal reconstruction A/D and D/A convertors digital-analogue conversion analogue-to-digital conversion reconstruction filter specifications research areas signal sampling interpolation DAC ADC ΣΔ noise-shaping techniques Signal processing and detection anti-alias reduction sigma-delta modulation ΣΔ converters design DSP systems signal resolution

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An along-the-channel model for proton exchange membrane fuel cells

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JOURNAL OF THE ELECTROCHEMICAL SOCIETY 1998年第4期145卷 1149-1159页

作者： Yi, JS Nguyen, TV Univ Kansas Dept Chem & Petr Engn Lawrence KS 66045 USA

An along-the-channel model is developed for evaluating the effects of various design and operating parameters on the performance of a proton exchange membrane (PEM) fuel cell. The model, which is based on a previous one, has been extended to include the convective water transport across the membrane by a pressure gradient, temperature distribution in the solid phase along the flow channel, and heat removal by natural convection and coflow and counterflow heat exchangers. Results from the model show that the performance of a PEM fuel cell could be improved by anode humidification and positive differential pressure between the cathode and anode to increase the back transport rate of water across the membrane. Results also show that effective heat removal is necessary for preventing excessive temperature which could lead to local membrane dehydration. For heat removal and distribution, the counterflow heat exchanger is most effective.

关键词： channel model Natural convection counter flow heat exchanger mucin 1 differential pressure Water transport membrane Anodes Proton exchange membrane fuel cells OPERATING PARAMETER heat removal pulse code modulation combination rate heat exchangers

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Simulation support in the search for an efficient speech coder

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SIMULATION 1998年第5期70卷 279-290页

作者： Al-Akaidi, M De Montfort Univ Fac Comp Sci & Engn Dept Elect Engn Leicester LE1 9BH Leics England

Speech coding is a well researched area, and researchers are making new proposals for improvements to current algorithms. The family of code-excitated linear prediction coders represents a recent breakthrough, which almost caters to the present need for low bit rates. In mobile communications, low bit-rate speech coders play a crucial role in spectrally efficient transmission. Theoretically, a rate of a few hundred bits per second is enough to code speech efficiently. Many coders have been developed using computationally intensive techniques that can achieve rates of 4 to 6 kilobits per second. Theoretically, there is room for improvement. The trend is to use analytical models of speech production and perception. This paper briefly reviews existing speech coders, identifies future trends in this research area and describes results obtained from simulating vowels and consonant waveforms and from a multi-pulse excitation/linear predictive speech coders algorithm.

关键词： speech coding speech codecs pulse code modulation linear predictive speech coders speech production speech prediction

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pulse code modulation: invented for microwaves, used everywhere

Pulse code modulation: invented for microwaves, used everywh...

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Proceedings of the International Conference on 100 Years of Radio

作者： Cattermole, K.W. Univ of Essex Essex United Kingdom

The great impetus to the invention of pulse code modulation was the collateral development of microwave radio. However, by the time that pulse code modulation became a practical system for telephony, microwave radio has for good reasons developed along analog lines. There was however an obvious application for pulse code modulation on cable, which led to near-universal implementation on transmission routes and ultimately to the digital integrated network. Digital techniques spread back into radio systems only after widespread usage elsewhere, and much technical development to adapt them to the medium.

关键词： pulse code modulation

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Technology of fixed wireless access

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TELECOMMUNICATIONS POLICY 1997年第5期21卷 437-450页

作者： Trinkwon, D NO TELECOM NORTEL FIXED WIRELESS ACCESSMARKET DEVRICHARDSONTX 75082 USA

The ability of different wireless technologies to co-exist within a single geographic area, owned and operated by different service providers with relatively simple sharing arrangements for common infrastructure is one of the key aspects that makes wireless technology a valuable addition to the universal service concept--in fact it can change the fundamental assumptions embodied within traditional approaches to universal service, This paper examines the challenge operators and regulators have in providing telecommunications services, especially to smaller communities, and the role that Wireline Equivalent Fixed Wireless Access systems can play. (C) 1997 Elsevier Science Ltd.

关键词： ADPCM Adaptive pulse code modulation ADSL Asynchronous Digital Subscriber Line AMPS Advanced Mobile Phone System/Service ANI Automatic Number Identification CATV Community Antenna Television CITEL Inter-American Telecommunications Commission CITI Columbia Institute for Teleinformation CPE Customer Premise Equipment DTMF Dual Tone Multifrequency FDMA Frequency Division Multiple Access FWA Fixed Wireless Access GSM General Service Mobile ISDN Integrated Services Digital Network ISDN BRI ISDN Basic Rate Interface ISDN PRI ISDN Primary Rate Interface LAN Local Area Network LEC Local Exchange Carrier LMDS Local Multipoint Distribution Service LNP Local Number Portability MMDS Multichannel Multipoint Distribution Service MOS Mean Opinion Score OA&M Operations Administration and Maintenance OAM&P Operations Administration Maintenance and Planning PACS Personal Access Communications System PBX Private Branch Exchange PCM pulse code modulation PCS Personal Communications Service PHS Personal Handi-phone System POTS Plain Old Telephone Service PSTN Public Switched Telephone Network SOHO Small Office Home Office SONET Synchronous Optical Network SS#7 Signaling System Number 7

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Serial concatenated trellis coded modulation with iterative decoding: design and performance

Serial concatenated trellis coded modulation with iterative ...

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Proceedings of the 1997 IEEE Global Telecommunications Mini-Conference

作者： Benedetto, S. Divsalar, D. Montorsi, G. Pollara, F. California Inst of Technology

In this paper, we propose a novel method to design serial concatenation of an outer convolutional code with an inner trellis code with multilevel amplitude/phase modulations and a suitable bit-by-bit iterative decoding structure. Existing two- and multi-dimensional TCM schemes cannot be used directly in serial concatenated TCM, as they lead to suboptimum performance. Therefore, a new input labeling method is proposed to construct optimum TCM. Examples are given for a bandwidth efficiency of 2 bits/sec/Hz with 2×8PSK and 16QAM modulations. Inner trellis codes were designed specifically for serially concatenated TCM. A simple iterative decoder for serial concatenated TCM is described. The performance of the code using 2×8PSK modulation with a two-state inner code, 8-state outer code, and input block of 16384 bits is within 0.85 dB from the Shannon limit, at a bit error probability of 10-7 for 2 bits/sec/Hz. This low complexity serial TCM outperforms parallel concatenated TCM at low bit error rates for the same complexity. Its performance is similar to more complex parallel concatenated TCM employing two 16-state constituent codes.

关键词： pulse code modulation

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