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Algorithm of simulation time synchronization over large-scale nodes

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Science in china(Series F) 2008年第9期51卷 1239-1255页

作者： ZHAO QinPing1,2.ZHOU Zhong1,2.& Lü Fang1,2.1 State Key Laboratory of Virtual Reality technology and Systems,Beihang university,{2.,china 2.school of computer Science and engineering,Beihang university,{2.,china State Key Laboratory of Virtual Reality technology and Systems Beihang University school of computer Science and {2. Beihang University

In distributed simulation, there is no uniform physical clock. And delay cannot be estimated because of jitter. So simulation time synchronization is essential for the event consistency among nodes. This paper investigates time synchronization algorithms over large-scale distributed nodes, analyzes LBTS （lower bound time stamp） computation model described in IEEE HLA standard, and then presents a grouped LBTS model. In fact, there is a default premise for existing algorithms that controi packets must be delivered via reliable transportation. Although, a theorem of time synchronization message＇s reliability is proposed, which proves that only those control messages that constrain time advance need reliability. It breaks out the default premise for reliability. Then multicast is introduced into the transmis- sion of control messages, and algorithm MCTS （multi-node coordination time synchronization） is proposed based on multicast. MCTS not only promotes the time advance efficiency, but also reduces the occupied network bandwidth. Experiment results demonstrate that the algorithm is better than others in both time advance speed and occupied network bandwidth. Its time advance speed is about 50 times per second when there are 1000 nodes, approximately equal to that of similar systems when there are 100 nodes.

关键词： distributed simulation time synchronization multi-node coordination LBTS multicast

Optimization of Fractal Iterated Function System(IFS) with Probability and Fractal Image Generation

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Journal of university of Science and technology {2. 2001年第2期8卷 152-156页

作者： Berthe Kya, Yang Yang (Information engineering school, {2. of Science and technology beijing, beijing 100083, china) Information engineering school University of Science and Technology Beijing 100083 China

There are several methods for rendering fractal images based on IFS (Iterated Function System) in computer graphic; but one concern of the computer graphic community has been the efficiency rendering algorithms. The invariant measures arising from IFSP (Iterate Function System with Probability) using the probabilistic algorithm are also known as chaos games. The role of these probabilities to generate the image of the attractor has been investigated using a multi-fractal analysis. The conventional choice of probability associated with each set /S/ to generate the attractor in least time possible is introduced, then a new method based on the self similarity and multi-fractal analysis is presented. The efficiency of the new method has been proved over the conventional method.

关键词： optimization of fractal IFS compression IFSP multi-fractal analysis

Theorems for Testing Local Activity of CNN and Application to Cardiac Purkinje Equations

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International Journal of Minerals,Metallurgy and Materials 2000年第2期14卷 139-146页

作者： Lequan Min(Applied Science school, university of Science and {2. beijing, beijing 100083, china) Applied Science school University of Science and Technology Beijing Beijing 100083 China

The theorems for testing the local in one-port cellular neural/inear network (CNN) cells with four local state variables are presented. Using the theorems computes the bifurcation diagrams of the cardiac Purkinje fiber (CPE) equations Which describethe long-lasting action and pace-maker potentials of the Purkinje fiber of the heart. The computer simulation shows that periodic trajectories or convergent trajectories of the CPF Equations can be foun if the cormsponing cell Parameters are located in a positive domainbut nearby edge of chaos. In particular a heart with approximate normal frequency of heartbeat but non-normal electrocardiogram maysuddenly stop by slightly perturbing the parameters of the corresponding CPF Equations when the Paramders are located nearby the edge of chaos in the bifurcation diagrams. This research seems to interpret reasonbly the phenomena that patients with cardiac diseases might suddenly die without warning.

关键词： cellular neural network local activity cardiac Purkinje fiber heartbeat

Change Laws of Flake's Temperature during Making a Diamond Film by DC-PJ

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International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 97-102页

作者： Xuhong Chen Lihe Zhao Fanxiu Lu(Mechanical engineering school, {2. of Science and technology beijing, beijing 100083, china) Mechanical engineering school University of Science and Technology Beijing Beijing 100083 China

When making a diamond film by direct current plasma jet, a kind piece of flake is used as a base body Which the film can beattached to. The flake's temperature is unstable. Therefore, some experiments and constructed mathematical models, which were solvedby computer, were done. The results show that the flake's temperature is influenced by many factors and the mains are plasma jet powerand vacuum pressure. Through adjusting the two parameters, the flake's temperature can be accurately controlled, furthermore, diamondfilms' quality would be improved. Lowering sediment platform's temperature has a little effect to the flake's temperature at present technology conditions.

关键词： CVD (Chemical Vapor Deposition) plasma, impact heat transfer

Performance Modeling and Approximate Analysis of Multiserver Multiqueue Systems with Poisson and Self-similar Arrivals

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Journal of university of Science and technology {2. 2001年第2期8卷 145-151页

作者： Zhiguang Shan, Chuang Lin, Yang Yang, Yan Wang (Information engineering school, {2. of Science and technology beijing, beijing 100083, china) (Department of computer Science and technology, Tsinghua {2., beijing 100084, china) Information engineering school University of Science and Technology Beijing 100083 China

The problem of state space explosion is still ran outstanding challenge in Markovian performance analysis for multiserver multiqueue (MSMQ) systems. The system behavior of a MSMQ system is described using stochastic high-level Petri net (SHLPN) models, and an approximate performance analysis technique is proposed based on decomposition and refinement methods as well as iteration technique. A real MSMQ system, Web-server cluster, is investigated. The performance of an integrated scheme of request dispatching and scheduling is analyzed with both Poisson and self-similar request arrivals. The study shows that the approximate analysis technique significantly reduces the complexity of the model solution and is also efficient for accuracy of numerical results.

关键词： multiserver multiqueue (MSMQ) system Web-server cluster performance analysis stochastic high-level Petri net (SHLPN) request dispatching request scheduling

Fuzzy tracking control design for hypersonic vehicles via T-S model

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Science china(Information Sciences) 2011年第3期54卷 521-528页

作者： GAO DaoXiang 1 & SUN ZengQi 2.1 school of technology, {2. Forestry university, beijing 100083, china 2.State Key Laboratory of Intelligent technology and System, Department of computer Science and technology, Tsinghua university, {2. 100084, china school of technology Beijing Forestry University State Key Laboratory of Intelligent technology and System Department of Computer Science and Technology Tsinghua University

The main focus of this paper is on designing a T-S fuzzy controller for the hypersonic vehicle. The longitudinal dynamics of the vehicle are studied using time-scale decomposition to reduce the complexity of T-S modeling. The dynamic inversion with PI control technique is applied for the slow dynamics to derive the flight path angle command and throttle setting by taking the pilot altitude and velocity command as its inputs. The T-S fuzzy controller is designed for the fast dynamics to derive the elevator deflection to track the flight path angle command. The discrepancy between the T-S model and real vehicle model is considered by using sliding mode control for the system stability. Simulation results are included to show the effectiveness of the controller.

关键词： fuzzy control T-S model sliding mode control hypersonic vehicle

Synchronization of Digital Chaos in Secure Communication Systems

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Journal of university of Science and technology {2. 2001年第4期8卷 299-305页

作者： Geng Zhao, Deling Zheng, ShaojunHuang 1)College of Electric Science and technology beijing. beijing 100070, china 2.Information engineering school, university of Science and technology beijing. beijing 100083, china College of Electric Science and technology beijing Beijing 100070 China Information engineering school University of Science and Technology Beijing Beijing 100083 China

The theories of synchronization based on secure communications using digital chaos are presented. A new synchronous method-cycles-interval Pulse drive is developed and realized. Experimental results show it is available, and in order to reduce synchronous noise, a method using model references solves the ratio of signal power to noise power, so the secure communication system can be realized.

关键词： digital chaotic synchronization cycles-interval pulses drive synchronous noise model reference

A new method for simulating human emotions

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Journal of university of Science and technology {2. 2003年第2期10卷 72-74页

作者： Weimin Xue, Zhiliang Wang, Wenhong Xia, and Wenbo MengInformation engineering school, {2. of Science and technology beijing, beijing 100083, china Information engineering school University of Science and Technology Beijing Beijing 100083 China

How to make machines express emotions would be instrumental in establishing acompletely new paradigm for man machine interaction. A new method for simulating and assessingartificial psychology has been developed for the research of the emotion robot. The human psychologyactivity is regarded as a Markov process. An emotion space and psychology model is constructedbased on Markov process. The conception of emotion entropy is presented to assess the artificialemotion complexity. The simulating results play up to human psychology activity. This model can alsobe applied to consumer-friendly human-computer interfaces, and interactive video etc.

关键词： emotion robot psychology entropy Markov model artificial psychology

Interactive graphics mechanical optimum design

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International Journal of Minerals,Metallurgy and Materials 1997年第3期11卷 54-56页

作者： WANG Guobiao (Resources engineering school, {2. of Science and technology beijing, beijing 100083, china)

Virtually all conventional optimizations are Performed in a batch computer environment. No graphic information during the optimization process is provided. The research tactics and implementation procedure of interactivegraphics in mechanical optimum design are presented. An interactive Graphics Mechanical Optimum Design Program(IGMODP) for microcomputers is developed. The example of wheeled loader' s working device optimum design usingIGMODP is carried out.

关键词： interactive graphics mechanical optimum design computer program