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第十五届国际光伏科学与工程大会

作者： PANG Huey LO Edward W.C. CHUNG,T.S. CLOSE Josie Department of Electrical Engineering The Hong Kong Polytechnic University Hung Horn Hong Kong SAR China Department of Electrical Engineering The Hong Kong Polytechnic University Hung Horn Hong Kong SAR China Department of Electrical Engineering The Hong Kong Polytechnic University Hung Horn Hong Kong SAR China Department of Architecture The University of Hong Kong 3/F Knowles Building Pok Fu Lam Road Hong Kong SAR China

The purpose of this paper is to develop a mathematical model for hybrid solar parabolic trough concentrator (PTC) systems. The model is for estimation of energy outputs, losses and efficiencies of various parts of the system when the system is operating under different climate condition, diverse system configurations and a range of loading conditions. Automated system optimization can also be quickly obtained by trying numerous different system configurations. In hybrid PTC system, photovoltaic cells are also installed on the receiver pipes, solar energy is directly converted to electrical energy by the photovoltaic cells. The working fluid circulating in the receiver pipes is for solar thermal purpose as well as to cool down the temperature of solar cells. The overall yield of the system is increased and therefore capital cost is reduced. A detailed analytical model simulating a hybrid PTC system has been developed by modelling and integrating sub-components into one model and a simulation software has been developed. The software is a valuable design tools for engineers whenever they are designing hybrid PTC systems, which are likely feasible in application to densely populated city with sub-tropical climatic conditions in southern part of China. System performance has been tested with a set of initial parameters and preliminary results have been produced.

关键词： parabolic trough concentrator photovoltaic hybrid CIS

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Experimental study on elastic modulus of lime soil under dynamic loading

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Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and engineering 2005年第SUPPL.期24卷 4715-4719页

作者： Li, Ji-Xiang He, Jian-Qing Zhang, Jia-Sheng Department of Civil Engineering Wuhan Polytechnic University Wuhan 430023 China School of Civil Engineering and Soil Architecture Central South University Changsha 410075 China

Based on a lot of dynamic triaxial tests, the variation laws of dynamic elastic modulus of lime soil sample were studied. Meanwhile, the influences of lime dosage ratio, consolidation ratio, and frequency on elastic modulus were investigated. It is concluded that the relationship between elastic modulus and dynamic strain of lime soil is similar to that of natural soil. The elastic modulus increases as the confining pressure increases at the same level. With dosage ratio increasing, the elastic modulus also increases, and when it exceeds 5%, the elastic modulus increases evidently. The influence of consolidation ratio on modulus is significant. At a lower strain, the modulus increases with the consolidation of ratio increasing. When strain exceeds a certain value, the modulus decreases with consolidation ratio increasing. The higher the frequency is, the larger the modulus is. But the influence of frequency on modulus is not as evident as above factors. It is verified that the way to adopt the soft soil of unfavourable mechanical properties by adding lime as road fillings is economical and practicable. The achieved conclusions can provide a useful guidance for the preliminary estimation of lime requirements to improve the dynamic properties of clays.

关键词： Soil mechanics

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A wavelet based distributed ID model

A wavelet based distributed ID model

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IEEE International Conference on Services Computing (SCC)

作者： Lan Liu Zhitang Li Yong Xu Chenggang Mei Xiaoling Tan Department of Computer Architecture Huangzhong University of Science and Technology Wuhan Hubei China Department of Electronic Information Guangdong Polytechnic Normal University Guangzhou Guangdong China Department of Computer Science South China University of Technology Guangzhou Guangdong China Department of Electronic Engineering Chongqing Three Gorges University Chongqing China

This paper develops a wavelet based distributed ID model approach to analyses network traffic in detail. We adopt wavelet technique to analyze and model ID system to find the attack behavior in network. Our model can post attack characteristic more clearly and, by way of improve the veracity, we compare corresponding network node signals of wavelet decomposition. We simulate attacks and the model can detect attack more precisely than the previous model does.

关键词： Wavelet analysis Frequency synthesizers Telecommunication traffic Traffic control Signal analysis Wavelet coefficients Power system modeling Signal synthesis Prototypes Performance analysis

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Axial compression test of cut cold-formed steel stub columns with c-section

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology 2005年第7期27卷 57-60页

作者： Wang, Xiao-Ping Chung, Kwok-Fai Lam, Siu-Shu School of Civil Engineering and Architecture Wuhan University of Technology Wuhan 430070 China Department of Civil and Structural Engineering Hong Kong Polytechnic University Hong Kong Hong Kong

Cutting roll-formed steel C-section to stub columns will produce different extent of cross section distortion along the lengths and cause additional initial geometric imperfections. Ten cut stub columns with two rolled-formed steel C-section types were tested under the axial compressive load. The ultimate compressive strength was calculated for the stub columns base on steel design code GB50018-2002. For all the cut stub columns, the failure modes of the two flanges were obvious distortional mode, while the webs were local buckling failure. The testing compressive ultimate strength was only 83%-89% of code calculation value.

关键词： C-section Cold-formed steel Compressive test Cut Stub columns

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Effect of cutting on initial geometric imperfections of cold-formed steel stub columns with C-section

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology 2005年第6期27卷 58-61页

作者： Wang, Xiao-Ping Lam, Siu-Shu Chung, Kwok-Fai School of Civil Engineering and Architecture Wuhan University of Technology Wuhan 430070 China Department of Civil and Structural Engineering Hong Kong Polytechnic University Hung Hum Hong Kong Hong Kong

Two kinds of roll-formed steel C-sections were taken as the research object. Stub columns were cut from the middle of long members. The cross section distortion and geometric imperfections along the length of the cut stub columns were measured. Measurement results showed that there was obvious cross section distortion in the cut stub columns after cutting, resulting in the large additional initial geometric imperfections along the length, which would affect the axial compressive ultimate strength and the failure modes of the cut stub columns.

关键词： C-section Cold-formed steel Cross section distortion Cutting Initial geometric imperfection

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Computational fluid dynamics simulation of fire-induced air flow in a large space building: Key points to note

Computational fluid dynamics simulation of fire-induced air ...

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2004 ASME Heat Transfer/Fluids engineering Summer Conference, HT/FED 2004

作者： Li, Y.F. Chow, W.K. College of Architecture and Civil Engineering Beijing University of Technology Beijing 100022 China Department of Building Services Engineering Hong Kong Polytechnic University Hong Kong Hong Kong

Fire-induced air flow in a large span building by computational fluid dynamics (CFD) will be discussed in this paper. The CFD model is based on Reynolds Averaging Navier-Stokes (RANS) equations with k-Ε based turbulence model for predicting velocity, pressure and temperature distribution. This technique is commonly used in practical design for smoke management system. The fire is taken as a volumetric heat source and buoyancy effects are included in equations for the vertical momentum and turbulent parameters. Several key points to note in the simulation will be discussed. These are: Relaxation factor and convergence criteria. False diffusion. Sudden changes in flow parameters across the heat source. A large terminal hall with 1 MW fire is taken as an example to discuss the above points. The fire scenarios in a region of interest will be assessed by CFD. Copyright © 2004 by ASME.

关键词： Computational fluid dynamics

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Disputes arising from vaguely defined contractual responsibilities in building services maintenance contracts

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Facilities 2004年第1/2期22卷 44-52页

作者： Lai, Joseph H.k. Yik, Francis W.H. Jones, Phil Department of Building Services Engineering The Hong Kong Polytechnic University Hunghom Kowloon Hong Kong SAR Hong Kong Welsh School of Architecture Cardiff University Cardiff United Kingdom

A clear definition of the responsibilities of the contracting parties is crucial to any contract. However, many building services maintenance contracts contain vague terms that are often causes of disputes, suspension of work, unsatisfactory performance and financial losses. Common vague contract terms include those that require the contractor to be responsible for any replacement and restoration work arising from “fair wear and tear” and “vandalism”. Reports the findings of a survey of maintenance practitioners’ interpretations of these terms, and their experience with the use of such terms in building services maintenance contracts in Hong Kong. © 2004, Emerald Group Publishing Limited

关键词： Building services Contract law Disputes Hong Kong Maintenance Vandalism Wear

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Product design and innovation: Combining the social sciences, design, and engineering

Product design and innovation: Combining the social sciences...

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ASEE 2004 Annual Conference and Exposition, "engineering Researchs New Heights"

作者： Gabriele, Gary A. Bronet, Frances Kagan, Larry Eglash, Ron Hess, David Seruya, Barbara Rensselaer Polytechnic Institute Troy NY 12180 Rensselaer Polytechnic Institute Dept. of Mechanical Engineering Troy NY 12180 Rensselaer Polytechnic Institute School of Architecture Troy NY 12180 Rensselaer Polytechnic Institute Department of the Arts Troy NY 12180 Rensselaer Polytechnic Institute Dept. of Sci. and Technology Studies Troy NY 12180 Barbara Seruya and Associates New York NY 10014

The Product Design and Innovation (PDI) program designed to educate engineering students on the application of engineering knowledge on product development is discussed. The students learn to incorporate graphics and creativity to design products and services to improve the quality of life. The design studio helps them to enhance their ability to find problems and formulate ideas. PDI prepares students to become innovative designers who can integrate advanced technologies in designing new generation products.

关键词： engineering education

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A longitudinal analysis on the relationship between construction output and GDP in Hong Kong

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Construction Management and Economics 2004年第4期22卷 339-345页

作者： Yiu, C.Y. Lu, X.H. Leung, M.Y. Jin, W.X. Department of Building/Real Estate Hong Kong Polytechnic University Hong Kong Hong Kong Dept. of Mgmt. Science/Engineering University of Shanghai Shanghai China Department of Building/Construction City University of Hong Kong Hong Kong Hong Kong Faculty of Management Xian Univ. of Architecture/Technol. Xian China

The relationship between construction output and economic growth has been well discussed by construction economists. Most of the previous studies found a positive correlation between gross domestic product (GDP) per capita and various measures of construction output. However, cross-sectional analysis was commonly adopted but longitudinal analysis has been called upon. Furthermore, recent research argued that non-linear relationship between GDP and construction output exists because of different stages of economic development in different countries. They explained the phenomenon by means of the change of the growth rates of construction output at different stages of economic development, but the argument has not yet been rigorously tested. With the availability of long time-series of data of Hong Kong construction industry, this paper attempts to test longitudinally the relationship between the real growth rate of construction output and the real growth rate of GDP. It was found that the growth rate of GDP led that of construction output, and as the growth rate of GDP increased, the growth rate of construction output was marginally diminishing. It agrees with the proposition that construction industry is relatively inefficient in productivity improvement and the accumulation of capital investment results in a marginally diminishing growth of construction output. © 2004 Taylor & Francis Ltd.

关键词： Industrial economics

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Sound Decay Analysis in Acoustically Coupled Spaces Using a Re‐Parameterized Decay Model

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AIP Conference Proceedings 2004年第1期735卷 96-103页

作者： Paul M. Goggans Ning Xiang Chung Yong Chan Ying Chi *University of Mississippi Department of Electrical Engineering University MS 38677 †Rensselaer Polytechnic Institute School of Architecture Troy NY 12180

The sound energy decay characteristics of coupled spaces are of increasing interest to architectural acousticians. Coupled spaces occur naturally in concert halls and theaters due to the presence, for example, of balconies, orchestra pits, and stage houses. In addition, many new halls have incorporated hard chambers coupled to the primary space to achieve a flexible variation of the acoustics. In certain conditions, sound energy in these coupled spaces decays with two or more distinct exponential rate constants. The presence of multiple decay rates can have a distinct impact on a hall’s perceived acoustical quality. In previous papers we describe our initial work to apply Bayesian inferential methods to the problem of determining multiple decay times in coupled spaces using Schroeder energy decay functions derived from measured room impulse responses. In our previous work, relatively little prior information about parameters of the decay model is incorporated in the inference calculations in spite of the fact that much information regarding both the possible range of the parameters and the relationship between the parameters is known. In this paper we describe our recent efforts to incorporate this prior information into the inference calculations by re‐parameterizing the multi‐exponential decay model.

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