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Generalized Self-Adaptive Genetic Algorithms

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International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 72-75页

作者： Bin Wu Xuyan Tu Jian Wu Information engineering School, University of science and {2. beijing, beijing 100083, china department of Information and Control engineering, Southwest institute of {2., Mianyang 62.002. china Information engineering School University of Science and Technology Beijing Beijing 100083 China department of Information and Control engineering Southwest Institute of Technology Mianyang 621002 China

In order to solve the problem between searching performance and convergence of genetic algorithms, a fast genetic algorithm generalized self-adaptive genetic algorithm (GSAGA) is presented. (1) Evenly distributed initial population is generated. (2. Superior individuals are not broken because of crossover and mutation operation for they are sent to subgeneration directly. (3) High quality im- migrants are introduced according to the condition of the population schema. (4) Crossover and mutation are operated on self-adaptation. Therefore, GSAGA solves the coordination problem between convergence and searching performance. In GSAGA, the searching per- formance and global convergence are greatly improved compared with many existing genetic algorithms. Through simulation, the val- idity of this modified genetic algorithm is proved.

关键词： generalized self-adaptive genetic algorithm initial population immigration fitness function

Invariant Measures for a Random Evolution Equation with Small Perturbations

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Acta Mathematica Sinica,English Series 2001年第4期17卷 631-642页

作者： Fu Bao XI department of Applied Mathematics, beijing institute of technology,{2., P. R. china department of Applied Mathematics Beijing Institute of Technology Beijing 100081 P. R. China

In this paper we consider a random evolution equation with small perturbations, and show how to construct coupled solutions to the equation. As applications, we prove the Feller continuity of the solutions and the existence and uniqueness of invariant measures. Furthermore, we establish a large deviations principle for the family of invariant measures as the perturbations tend to zero.

关键词： Invariant measures Large deviations Coupling Random evolution equation

Formation control for networked spacecraft in deep space:with or without communication delays and with switching topology

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science china(Information sciences) 2011年第3期54卷 469-481页

作者： WANG Nan 1,2. ZHANG TianWu 2.& XU JieQiong 1 1 School of Aeronautic science and engineering, {2. University of Aeronautics and Astronautics, {2. 100191, china 2.department of computer science and engineering, Henan institute of engineering, Zhengzhou 451191, china 1. School of Aeronautic science and engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China2. Department of Computer Science and Engineering Henan Institute of Engineering Zhengzhou 451191 China

In this paper, several formation controllers are developed with constant and variable connected communication topology for six-degree-of-freedom (6-DOF) networked spacecraft flying in deep space with constant and time-varying communication delays considered. In the control algorithm, any explicit leader does not exist in the formation team and it is required that each spacecraft communicate only with its neighbors and therefore the required communication loads of the whole formation is greatly reduced. The proposed control strategies allow that each spacecraft can track its desired position and attitude and simultaneously the whole group moves to the desired formation and obtain its desired relative attitudes with its neighbors. Simulation results demonstrate the effectiveness of the proposed controllers.

关键词： deep space graph theory formation control communication topology delays

On the periodic solutions of a type of differential-iterative equations

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Chinese science Bulletin 1998年第3期43卷 204-206页

作者： GE Weigao 1, LIU Zhengrong 2.and YU Yuanhong 3 1. department of Applied Mathematics, beijing institute of technology,{2., china 2. department of Mathematics, Yunnan University, Kunming 650091, china 3. institute of Applied Mathematics, C department of Applied Mathematics Beijing Institute of Technology Beijing China department of Mathematics Yunnan University Kunming China institute of Applied Mathematics Chinese Academy of Sciences Beijing China

Sufficient conditions for the existence of periodic solutions to a type of nonautonomous differential_iterative equations are given.

关键词： differential_iterative equation periodic solution fixed point.

Statistic characteristic analysis of forward scattering surface clutter in bistatic radar

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science china(Information sciences) 2010年第12期53卷 2675-2686页

作者： HU Cheng ,LONG Teng & ZENG Tao Radar Research Lab,department of Electronic engineering,{2. institute of technology,{2. 100081,china 1. Radar Research Lab Department of Electronic Engineering Beijing Institute of Technology Beijing 100081 China

In this paper,based on the processing results of measured forward scattering clutter data in bistatic radar,using the Gaussian distribution model,Exponential distribution model,Power-Law distribution model,high order Auto-Regressive model and so on,the probability density distribution and power spectrum mathematical model are obtained,and the impact of clutter statistic models on target detection performance is analytically derived from statistic *** to the estimated clutter probability distribution,power spectrum model and generalized matching filter theory,the forward scattering clutter in bistatic radar is effectively suppressed and the target motion parameters are accurately estimated from the measured clutter data.

关键词： bistatic radar forward scattering surface clutter clutter probability density function clutter power spectrum model target detection performance

New progress in the principle of nonequilibrium statistical physics

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Chinese science Bulletin 2001年第6期46卷 448-454页

作者： XING Xiusandepartment of Applied Physics, beijing institute of technology,{2., china department of Applied Physics Beijing Institute of Technology Beijing China

In recent years, a new fundamental equation of nonequilibrium statistical physics was proposed in place of the Liouville equation. That is the anomalous Langevin equation in (?) space or its equivalent Liouville diffusion equation of time-reversal asymmetry. This equation reflects that the form of motion of particles in statistical thermody-namic systems has the drift-diffusion duality and the law of motion of statistical thermodynamics is stochastic in essence, but does not obey the Newton equation of motion, though it is also constrained by dynamics. The stochastic diffusion of the particles is the microscopic origin of macroscopic irre-versibility. Starting from this equation, the BBGKY diffusion equation hierarchy was presented, the hydrodynamic equations, such as the generalized Navier-Stokes equation, the mass drift-diffusion equation and the thermal conductivity equation have been derived succinctly. The unified description of all three level equations of microscopic, kinetic and hydrodynamic

关键词： anomalous Langevin equation in space drift-diffusion duality stochastic law nonequilibrium entropy evolution equation entropy diffusion.

Application of asymptotic waveform approximation technique to hybrid FE/BI method for 3D scattering

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science in china(Series F) 2007年第1期50卷 124-134页

作者： PENG Zhen1,2.3 & SHENG XinQing2.1 institute of Electronics, Chinese Academy of sciences, {2. 100080, china 2.department of Electronic engineering, beijing institute of technology, beijing 100081, china 3 Graduated University of Chinese Academy of sciences, {2. 100039, china 1. institute of Electronics Chinese Academy of Sciences Beijing 100080 China 2. department of Electronic engineering Beijing Institute of Technology Beijing 100081 China 3. Graduated University of Chinese Academy of sciences Beijing 100039 China

The asymptotic waveform evaluation （AWE） technique is a rational function approximation method in computational mathemetics, which is used in many appllcations in computational electromagnetlca. In this paper, the performance of the AWE technique in conjunction with hybrid finite element/boundary integral （FE/BI） method is firstly Inveetlgeted. The formuletlon of the AWE applied in hybrid FE/BI method is given in detail. The characteristic implementation of the application of the AWE to the hybrid FE/BI method is discussed. Numarlcel results demonstrate that the AWE technique can greatly speed up the hybrid FE/BI method to acquire wide-band and wide-angle backecatter radar-cross-section （RCS） by complex targets.

关键词： hybrid FE/BI AWE electromagnetic scattering RCS

Compactness in fuzzy logic

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Chinese science Bulletin 1998年第14期43卷 1166-1171页

作者： YING Mingsheng department of computer {2. and technology, Tsinghua University, beijing 100084, china department of computer {2. and technology Tsinghua University Beijing China

Compactness in Pavelka’s fuzzy logic for some compact lattices of truth values is shown, and the concept of gradual compactness is introduced to establish some corresponding results in a more general setting.

关键词： fuzzy logic compactness gradual compactness.

The Process of TiB_2.Cu Composite Phase and Structure Formation during Combustion Synthesis

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Journal of Wuhan University of technology(Materials science) 2006年第4期21卷 113-116页

作者：徐强 School of Materials science and engineering Beijing Insitute of TechnologyBeijing 100081China

The reaction process of combustion synthesis for TiB2.-Cu was investigated in detail using combustion-wave arresting experiment, X-ray diffraction （ XRD ） analysis, SEM analysis and differential thermal analysis （ DTA ）. The XRD analysis results for the different parts of the quenched specimen show that TiCux intermetallic phase firstly forms with the propagation of combustion wave, and then Ti1.87 B50 and Ti3B4 metastable phases come forth due to the diffusion of B atoms and finally the stable TiB2.phase forms because of the continuous diffusion of B atoms. The formation of TiB2.phase is uot completed by one step, but undergoes several transient processes. The process of reaction synthesis for Ti-B-Cu ternary system can be divided into three main stages： melting of Cu and Ti , and the formation of Cu- Ti melt and few TiCux , TiBx intermetallic phases ; large numbers of TiCux intermetallic phases formation and some fine TiB2.particles precipitation ; and the TiB2.particles coarsening and the stable TiB2.and Cu two phases formation in the final product.

关键词： combustion synthesis reaction process TiB2.phase combustion-wave arresting experiment