坦克稳定器的神经滑模控制方法

针对坦克稳定器这一类非线性和不确定性的复杂控制对象,提出一种神经滑模控制方法。该方法将滑模控制与神经网络相结合,解决了控制系统跟踪性能和鲁棒性能之间的矛盾。系统中的滑模控制器保证了系统的快速跟踪性能;而神经网络具有很强的自学习功能,通过学习能够保证系统的稳定性,同时可对扰动和参数变化进行有效的抑制补偿,从而在不牺牲系统鲁棒性的同时达到削弱抖振的目的。从理论上证明了滑动平面的稳定性,并且通过仿真验证了该结果。仿真结果表明该设计方法优于经典设计,为实际设计提供了一种可行的新方法。     

求解非线性规划的小生境遗传模拟退火算法

提出了用小生境遗传模拟退火算法求解带复杂约束的非线性规划问题。首先分析了遗传算法＂早熟＂收敛以及局部搜索能力弱的不足,由此引入小生境以增加种群多样性,并抑制＂早熟＂收敛现象,同时引入模拟退火算法以增强局部搜索能力,改进进化后期收敛速度慢的不足,最后结合典型非线性规划算例验证了混合算法的效率、精度和可靠性。     

一类非线性问题的数值分析

利用Ｌａｐｌａｃｅ方程的基本解,将变系数非齐次Ｈｅｌｍｈｏｌｔｚ偏微分方程的边值问题化为积分方程问题。再用边界无法进行离散,并对区域结点及边界结点的方程耦合求解。文末算例表明本文方法能够达到较高精度。     

Optimal service and arrival rates in Jackson queueing networks

In this paper we present an algorithm for solving a class of queueing network design problems. Specifically, we focus on determining both service and arrival rates in an open Jackson network of queueing stations. This class of problems has been widely studied and used in a variety of applications, but not well solved due to the difficulty of the resulting optimization problems. As an example, consider the classic application in computer network design which involves determining the minimum cost line capacities and flow assignments while satisfying a queueing performance measure such as an upper limit on transmission delay. Other application areas requiring the selection of both service and arrival rates in a network of queues include the design of communication, manufacturing, and health care systems. These applications yield optimization problems that are difficult to solve because typically they are nonconvex, which means they may have many locally optimal solutions that are not necessarily globally optimal. Therefore, to obtain a globally optimal solution, we develop an efficient branch and bound algorithm that takes advantage of the problem structure. Computational testing on randomly generated problems and actual problems from a health care organization indicate that the algorithm is able to solve realistic sized problems in reasonable computing time on a laptop computer. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 1–17, 2000     

Optimal switchover times between two activities utilizing the same resource

The “gold‐mining” decision problem is concerned with the efficient utilization of a delicate mining equipment working in a number of different mines. Richard Bellman was the first to consider this type of a problem. The solution found by Bellman for the finite‐horizon, continuous‐time version of the problem with two mines is not overly realistic since he assumed that fractional parts of the same mining equipment could be used in different mines and this fraction could change instantaneously. In this paper, we provide some extensions to this model in order to produce more operational and realistic solutions. Our first model is concerned with developing an operational policy where the equipment may be switched from one mine to the other at most once during a finite horizon. In the next extension we incorporate a cost component in the objective function and assume that the horizon length is not fixed but it is the second decision variable. Structural properties of the optimal solutions are obtained using nonlinear programming. Each model and its solution is illustrated with a numerical example. The models developed here may have potential applications in other areas including production of items requiring the same machine or choosing a sequence of activities requiring the same resource. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 186–203, 2002; DOI 10.1002/nav.10008     

临近空间拦截弹非线性控制系统性能研究

针对临近空间高超声速拦截弹执行机构非线性特性影响控制系统响应,提出基于次优控制理论及bang-bang控制理论对该问题进行研究.针对舵偏角速率饱和影响控制系统响应,通过改进正定阵P,Q来确保系统响应特性;针对舵偏角饱和影响控制系统响应,通过建立bang-bang开关曲线,分析推导出开关切换次数及最优时间表达式;最后仿真结果表明临近空间拦截弹的舵偏角饱和严重影响飞行控制系统的快速性.     

系泊系统动力学特性的研究进展

综述了系泊系统动力学特性的研究现状和方法 ,讨论了所存在的问题及发展趋势 .     

一类非线性控制系统模型的数学分析

采用非线性分析的方法,研究了一类非线性控制系统模型,得到解的整体存在性。     

A novel formulation of material nonlinear analysis in structural mechanics

This article demonstrates a novel approach for material nonlinear analysis. This analysis procedure eliminates tedious and lengthy step by step incremental and then iterative procedure adopted classically and gives direct results in the linear as well as in nonlinear range of the material behavior. Use of elastic moduli is eliminated. Instead, stress and strain functions are used as the material input in the analysis procedure. These stress and strain functions are directly derived from the stress-strain behavior of the material by the method of curve fitting. This way, the whole stress-strain diagram is utilized in the analysis which naturally exposes the response of structure when loading is in nonlinear range of the material behavior. It is found that it is an excellent computational procedure adopted so far for material nonlinear analysis which gives very accurate results, easy to adopt and simple in calculations. The method eliminates all types of linearity assumptions in basic derivations of equations and hence, eliminates all types of possibility of errors in the analysis procedure as well. As it is required to know stress distribution in the structural body by proper modelling and structural idealization, the proposed analysis approach can be regarded as stress-based analysis procedure. Basic problems such as uniaxial problem, beam bending, and torsion problems are solved. It is found that approach is very suitable for solving the problems of fracture mechanics. Energy release rate for plate with center crack and double cantilever beam specimen is also evaluated. The approach solves the fracture problem with relative ease in strength of material style calculations. For all problems, results are compared with the classical displacement-based liner theory.     

一类脉冲时滞抛物型方程解的振动准则

讨论了一类含脉冲的时滞抛物型方程解的振动性,利用格林公式以及Jensen不等式,得出了该方程在一类边界条件下解的振动准则。