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Simulation of lightning strike in 2-D and 3-D with fractal theory and its application

Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2010年第22期30卷 127-134页

作者： Xu, Wei Chen, Shui-Ming He, Jin-Liang State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

Lighting causes great damage to power systems due to the stochastic nature of lightning discharges and the vulnerability of lightning leaders to various environments in the process of inception and propagation. In this work, the growth of diffusion limited aggregation (DLA) was adopted for reproducing branches and tortuosity of lightning channels in both 2-D and 3-D simulations. By comparing the fractal dimensions of natural lightning discharges and simulation results on various discharge settings, we discovered that a fractal coefficient η = 2 can deliver a credible model of lightning strikes. We further proved the consistency between simulation results and observations conducted in Japan during 2005 and 2006 winter seasons on lightning strikes to a windmill and its lightning-protection tower. But the credibility of the result needs to be verified by further experimental data, when the model extended from 2-D to 3-D. Moreover, striking probability and the shielding effect in the actual condition were analyzed with the proposed simulation model. © 2010 Chin. Soc. for Elec. Eng.

关键词： Fractal dimension

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Study on attitude of dynamic object based on binocular vision system

Study on attitude of dynamic object based on binocular visio...

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International Conference on Computer Application and System Modeling (ICCASM)

作者： Xiaoling Zhang Baofeng Zhang Yuchi Lin Tianjin Key Lab. for Control Theor. & Applic. in Complicated Syst. Tianjin University of Technology Tianjin CN Applications in Complicated Systems Tianjin University of Technology Tianjin China State Key Laboratory of Precision Measuring Technology and Instruments Tianjin University Tianjin China

The binocular vision measurement system is adopted in which two CCDs are used and their optic axes are vertical to obtain the attitude of dynamic shell. At first, the mathematic model of the measurement system with vertical optic axes is established, and the calibration and adjustment is implemented to make two CCDs' optical axes vertical and co-planarity. The axis vector of shell is obtained using the vertical principle of two CCDs' optical axes. Then the moving attitude of shell such as pitch angleθ, yaw angleψ is obtained by relationship between the vector of shell axis and the attitude of moving shell. The result of simulation experiment and analysis shows that the measurement method has higher precision, and can meet the measurement require on the dynamic parameter of moving object in long distance.

关键词： Instruments Lasers Optical imaging Global Positioning System Biomedical optical imaging Adaptive optics

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A new algorithm for mining global frequent itemsets in a stream

A new algorithm for mining global frequent itemsets in a str...

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6th International Conference on Fuzzy systems and Knowledge Discovery, FSKD 2009

作者： Guo, Lichao Su, Hongye Qu, Yu State Key Lab. of Industrial Control Technology Institute of Cyber-Systems and Control Zhejiang University Hangzhou 310027 China

ISBN: (纸本)9780769537351

To find global frequent itemsets in a multiple, continuous, rapid and time-varying data stream, a fast, incremental, real-time, and little-memory-cost algorithm should be used. Based on the max-frequency window model, a BHS summary structure and a novel algorithm called GGFI-MFW are proposed. It merely updates the summaries for subsets of the data new arrived and could directly generate the max-frequency for a given itemset without scanning the whole summary. Experiment results indicate that the proposed algorithm could efficiently find global frequent itemsets over a data stream with a small memory and perform overwhelming superiority for a large number of distinct items. © 2009 IEEE.

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Content-based and graph-based tag suggestion

Content-based and graph-based tag suggestion

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International Workshop on Discovery Challenge, DC 2009 at the European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases, ECML PKDD 2009

作者： Si, Xiance Liu, Zhiyuan Li, Peng Jiang, Qixia Sun, Maosong State Key Lab. on Intelligent Technology and Systems Dept. of Computer Science and Technology Tsinghua University Beijing 100084 China

Social tagging is a popular and convenient way to organize information. Automatic tag suggestion can ease the user's tagging activity. In this paper, we exam both content-based and graph-based methods for tag suggestion using the BibSonomy dataset, and describe our methods for ECML/PKDD Discovery Challenge 2009 submissions. In content-based tag suggestion, we propose a fast yet accurate method named Feature-Driven Tagging. In graph-based tag suggestion, we apply DiffusionRank to solve the problem, and get a better result than current state-of-the-art methods in cross-validation.

关键词： User interfaces

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THUIR at TREC 2009 Web track: Finding relevant and diverse results for large scale Web Search

THUIR at TREC 2009 Web track: Finding relevant and diverse r...

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18th Text REtrieval Conference, TREC 2009

作者： Li, Z.C. Chen, F. Xing, Q.L. Miao, J.W. Xue, Y.F. Zhu, T. Zhou, B. Cen, R.W. Liu, Y.Q. Zhang, M. Jin, Y.J. Ma, S.P. State Key Lab. of Intelligent Technology and Systems Dept. of Computer Science and Technology Tsinghua University Beijing 10084 China

This is the 8th year that IR group of Tsinghua University (THUIR) participates in TREC. This year we focus on Web track, which contains two tasks, namely ad hoc and diversity. On ad hoc task, we improved the efficiency of our distributed retrieval system TMiner to handle terabytes of Web data. Then three studies have been done, namely page quality estimation, ranking feature analysis, and model comparison. On diversity task, we proposed several new approaches on searching strategy, user intention detection, and duplication elimination. To mine user's intention, we proposed and compared two different strategies, namely "searching + content-based diversity' which is a kind of result clustering, and "user based diverse intention prediction + searching' which is in the branch of query expansion.

关键词： Search engines

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High level architecture evolved modular federation object model

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Journal of systems Engineering and Electronics 2009年第3期20卷 625-635页

作者： Wang Wenguang Xu Yongping Chen Xinx Chen Xin Li Qun Wang Weiping Coll. of Information System and Management National Univ. of Defense Technology Changsha 410073 P. R. China Beijing Key Lab. of Intelligent Telecommunications Software and Multimedia Beijing Univ. of Posts and Telecommunications Beijing 100876 P. R. China State Key Lab. for Complex Systems Simulation Beijing 100101 P. R. China

To improve the agility, dynamics, composability, reusability, and development efficiency restricted by monolithic federation object model （FOM）, a modular FOM is proposed by high level architecture （HLA） evolved product development group. This paper reviews the state-of-the-art of HLA evolved modular FOM. In particular, related concepts, the overall impact on HLA standards, extension principles, and merging processes are discussed. Also permitted and restricted combinations, and merging rules are provided, and the influence on HLA interface specification is given. The comparison between modular FOM and base object model （BOM） is performed to illustrate the importance of their combination. The applications of modular FOM are summarized. Finally, the significance to facilitate compoable simulation both in academia and practice is presented and future directions are pointed out.

关键词： model federation object model review modular federation object model base object model composability high level architecture evolved simulation.

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A comparative study of radial basis function neural networks in dynamic clustering algorithm

A comparative study of radial basis function neural networks...

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MIPPR 2009 - Pattern Recognition and Computer Vision: 6th International Symposium on Multispectral Image Processing and Pattern Recognition

作者： Zhou, Peng Li, Dehua Wu, Hong Zeng, Jun Chen, Feng State Key Lab. for Image Processing and Intelligent Control Institute for Pattern Recognition and Intelligence Huazhong University of Science and Technology Wuhan 430074 China

ISBN: (纸本)9780819478078

This paper developed two learning procedure, respectively, based on the orthogonal least squares (OLS) method and the "Innovation- Contribution" criterion (ICc) proposed newly. The orthogonal use of the stepwise-regression algorithm of the ICc mages the model structure independent of the selected term sequence and reduces the cluster region further as compared with orthogonal least squares (OLS). as the Bayesian information criteria (BIC) method is incorporate into the clustering process of the ICc, except for the widths of Gaussian functions, it has no other parameter that need tuning ,but the user is required to specify the tolerance ρ, which is relevant to noises and will be difficult to implement in the real system, for the OLS algorithm. The two algorithms are employed to the Radial Basis Function Neural Networks (RBFNN) to compare its performance for different noise nonlinear dynamic systems. Experimental results show that they provide an efficient approximation to the required results for fitting models, but the clustering procedures of the ICc is substantially better solutions than does the OLS. © 2009 Copyright SPIE - The International Society for Optical Engineering.

关键词： Radial basis function networks

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Modeling of Isomerization of C_8 Aromatics by Online Least Squares Support Vector Machine

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Chinese Journal of Chemical Engineering 2009年第3期17卷 437-444页

作者：李丽娟苏宏业褚建 College of Automation and Electrical Engineering Nanjing University of Technology State Key Lab. of Industrial Control Technology Institute of Cyber-systems and ControlZhejiang University

The least squares support vector regression (LS-SVR) is usually used for the modeling of single output system, but it is not well suitable for the actual multi-input-multi-output system. The paper aims at the modeling of multi-output systems by LS-SVR. The multi-output LS-SVR is derived in detail. To avoid the inversion of large matrix, the recursive algorithm of the parameters is given, which makes the online algorithm of LS-SVR practical. Since the computing time increases with the number of training samples, the sparseness is studied based on the pro-jection of online LS-SVR. The residual of projection less than a threshold is omitted, so that a lot of samples are kept out of the training set and the sparseness is obtained. The standard LS-SVR, nonsparse online LS-SVR and sparse online LS-SVR with different threshold are used for modeling the isomerization of C8 aromatics. The root-mean-square-error (RMSE), number of support vectors and running time of three algorithms are compared and the result indicates that the performance of sparse online LS-SVR is more favorable.

关键词： least squares support vector machine multi-variable online sparseness isomerization

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A reference model based adaptive fuzzy controller for nonlinear dynamic systems

A reference model based adaptive fuzzy controller for nonlin...

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6th International Conference on Fuzzy systems and Knowledge Discovery, FSKD 2009

作者： Li, Li Sun, Fuchun College of Computer and Information Engineering Tianjin Normal University Tianjin 300387 China Dept. of Computer Science and Technology State Key Lab. of Intelligent Technology and Systems Tsinghua University Beijing 100084 China

ISBN: (纸本)9780769537351

In this paper, we first present some dynamic TS fuzzy subsystems to approximate a nonlinear system. To make the subsystems asymptotically stable, the reference model with the same fuzzy sets of the system rule is established. A feedback controller is designed based on an exact approximation model. The control gain can be solved by LMI approach. Since in practical plant, there are parameters uncertainty and external disturbance in approximation models, we propose a new controller with an adaptive fuzzy control term to compensate the uncertainty and alleviate the disturbance. Lyapunov constitute techniques can prove the stability of the closed loop systems. The simulations results illustrate the effectiveness of this approach. © 2009 IEEE.

关键词： Closed loop systems

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Multi-step prediction error approach for MPC performance monitoring

Multi-step prediction error approach for MPC performance mon...

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作者： Zhao, Yu Chu, Jian Su, Hongye Huang, Biao State Key Lab. of Industrial Control Technology Institute of Cyber Systems and Control Zhejiang University Hangzhou China Department of Chemical and Materials Engineering University of Alberta Edmonton AB T6G 2G6 Canada

ISBN: (纸本)9783902661548

Performance monitoring of model predictive control systems (MPC) has received a great interest from both academia and industry. In recent years some novel approaches for multivariate control performance monitoring have been developed without the requirement of process models or interactor matrices. Among them the prediction error approach has been shown to be a promising one, but it is k-step prediction based and may not be fully comparable with the MPC objective that is multi-step prediction based. This paper develops a multi-step prediction error approach for performance monitoring of model predictive control systems, and demonstrates its application in an industrial MPC performance monitoring and diagnosis problem.

关键词： Model predictive control

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