曲面最短路径的粒子群优化算法研究

求两点沿自由曲面最短路径的关键是正确选择两点间沿曲面的路径.粒子群优化算法(PSO)是一种全局性的概率搜索算法,它在整个问题空间实施搜索,可以得到问题的全局最优解.将粒子群优化算法的思想引入到路径寻优中,采用圆弧逼近法进行初始逼近,提出了解决自由曲面最短路径的随机搜索算法.最后给出了数值实例,结果表明该算法具有容易实现、运算量小等特点.     

Response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control

We studied the response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control using the stochastic averaging method. First, the time-delayed feedback bang-bang control force is expressed approximately in terms of the system state variables without time delay. Then the averaged It6 stochastic differential equations for the system are derived using the stochastic averaging method. Finally, the response of the system is obtained by solving the Fokker-Plank-Kolmogorov （FPK） equation associated with the averaged lt6 equations. A Duffing oscillator with time-delayed feedback bang-bang control under combined harmonic and white noise excitations is taken as an example to illus- trate the proposed method. The analytical results are confirmed by digital simulation. We found that the time delay in feedback bang-bang control will deteriorate the control effectiveness and cause bifurcation of stochastic jump of Duffing oscillator.     

Optimization of time-delayed feedback control of seismically excited building structures

An optimization method for time-delayed feedback control of partially observable linear building structures subjected to seismic excitation is proposed. A time-delayed control problem of partially observable linear building structure under horizontal ground acceleration excitation is formulated and converted into that of completely observable linear structure by using separation principle. The time-delayed control forces are approximately expressed in terms of control forces without time delay. The control system is then governed by Itoe stochastic differential equations for the conditional means of system states and then transformed into those for the conditional means of modal energies by using the stochastic averaging method for quasi-Hamiltonian systems. The control law is assumed to be modal velocity feedback control with time delay and the unknown control gains are determined by the modal performance indices. A three-storey building structure is taken as example to illustrate the proposal method and the numerical results are confirmed by using Monte Carlo simulation.     

On stochastic optimal control of partially observable nonlinear quasi Hamiltonian systems

A stochastic optimal control strategy for partially observable nonlinear quasi Hamiltonian systems is proposed.The optimal control forces consist of two parts. The first part is determined by the conditions under which the stochastic optimal control problem of a partially observable nonlinear system is converted into that of a completely observable linear system. The second part is determined by solving the dynamical programming equation derived by applying the stochastic averaging method and stochastic dynamical programming principle to the completely observable linear control system. The response of the optimally controlled quasi Hamiltonian system is predicted by solving the averaged Fokker-Planck-Kolmogorov equation associated with the optimally controlled completely observable linear system and solving the Riccati equation for the estimated error of system states. An example is given to illustrate the procedure and effectiveness of the proposed control strategy.     

On stochastic optimal control of partially observable nonlinear quasi Hamiltonian systems

INTRODUCTION Since many actual control systems such asthose in structural engineering are subjected torandom excitations and the system states are esti-mated from measurements with random noise,stochastic optimal control of partially observablesystems is a research subject of much significance.One basic approach to this problem is to convert itinto the stochastic optimal control of completelyobservable systems using separation theorem(Wonham, 1968; Fleming and Rishel, 1975; Ben-so…     

一类不确定广义随机混杂系统的非脆弱控制器设计

本文研究一类不确定广义随机混杂系统的非脆弱控制问题。在连续子系统的控制器增益存在一般形式的加性摄动情况下,利用多Lyapunov函数和随机Lyapunov函数相结合的方法,确定控制器的增益,使整个混杂系统达到随机稳定。仿真实例验证了本方法的有效性。该方法适用于计算机集成制造系统及交通管理系统。     

追踪溯源话评价

系统功能语言学从社会文化角度出发,把情景语境类型化为语旨、语式和语域,以此推导出语言的人际、语篇、概念三大功能,但未涉及语篇体现出的语言使用者的评价意义.以马丁(James Martin)为首的功能学者继承并发展了系统功能语言学,以科研项目成果为基础形成评价系统理论.本文研究了评价系统的理论来源,产生的背景和形成过程.     

Markov过程修正的一则注记

随机过程修正广泛应用于研究随机过程，随机流与随机微分系统．在本篇论文中，我们讨论具有Feller半群的Markov过程的修正，并给了Markov过程在状态空间S为非紧时修正定理的证明，并应用此修正定理构造了一个Feller过程的例子．     

A new theoretical framework for analyzing stochastic global optimization algorithms

１　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｓｔｏｃｈａｓｔｉｃｇｌｏｂａｌｏｐｔｉｍｉｚａｔｉｏｎａｌｇｏｒｉｔｈｍｉｓｃｏｎｃｅｒｎｅｄｗｉｔｈｕｓｉｎｇｒａｎｄｏｍｌｙｇｅｎｅｒａｔｅｄｐｏｉｎｔｓｔｏａｐｐｒｏｘｉｍａｔｅｏｐｔｉｍａｌｓｏｌｕｔｉｏｎｏｆｍａｔｈｅｍａｔｉｃａｌｐｒｏｇｒａｍｍｉｎｇ（ｓｅｅＲｅｆｓ．１～３ｆｏｒａｓｕｒｖｅｙｏｆｔｈｅｆｉｅｌｄ）．Ｆｏｒｓｏｍｅｓｔｏｃｈａｓｔｉｃｇｌｏｂａｌｏｐｔｉｍｉｚａｔｉｏｎａｌｇｏｒｉｔｈｍｓ,ｔｈｅｎｅｘｔｐｏｉｎｔｓｉｎｔｈｅｓｅｑ…     

Simultaneous perturbation stochastic approximation algorithm combined with neural network and fuzzy simulation

In order to solve three kinds of fuzzy programm model, fuzzy chance-constrained programming mode ng models, i.e. fuzzy expected value and fuzzy dependent-chance programming model, a simultaneous perturbation stochastic approximation algorithm is proposed by integrating neural network with fuzzy simulation. At first, fuzzy simulation is used to generate a set of input-output data. Then a neural network is trained according to the set. Finally, the trained neural network is embedded in simultaneous perturbation stochastic approximation algorithm. Simultaneous perturbation stochastic approximation algorithm is used to search the optimal solution. Two numerical examples are presented to illustrate the effectiveness of the proposed algorithm.     

Nonlinear stochastic optimal bounded control of hysteretic systems with actuator saturation

A modified nonlinear stochastic optimal bounded control strategy for random excited hysteretic systems with actuator saturation is proposed. First, a controlled hysteretic system is converted into an equivalent nonlinear nonhysteretic stochastic system. Then, the partially averaged Itoe stochastic differential equation and dynamical programming equation are established, respectively, by using the stochastic averaging method for quasi non-integrable Hamiltonian systems and stochastic dynamical programming principle, from which the optimal control law consisting of optimal unbounded control and bang-bang control is derived. Finally, the response of optimally controlled system is predicted by solving the Fokker-Planck-Kolmogorov （FPK） equation associated with the fully averaged Itoe equation. Numerical results show that the proposed control strategy has high control effectiveness and efficiency.     

Optimal coordinated voltage control of power systems

INTRODUCTION Voltage security control as an indispensable fa- cility in power systems aims at mid or long term voltage quality maintenance of power systems in the presence of load and/or transmission line disturbances. Most results of earlier research have been reported on transient stabilization and network control for voltage security of power systems, with various techniques originated from modern control methodology such as dynamic programming (Popovic et al., 2002; Wu et al., 2001), …     

Indexing the bit-code and distance for fast KNN search in high-dimensional spaces

Various index structures have recently been proposed to facilitate high-dimensional KNN queries, among which the techniques of approximate vector presentation and one-dimensional (1D) transformation can break the curse of dimensionality. Based on the two techniques above, a novel high-dimensional index is proposed, called Bit-code and Distance based index (BD). BD is based on a special partitioning strategy which is optimized for high-dimensional data. By the definitions of bit code and transformation function, a high-dimensional vector can be first approximately represented and then transformed into a 1D vector, the key managed by a B -tree. A new KNN search algorithm is also proposed that exploits the bit code and distance to prune the search space more effectively. Results of extensive experiments using both synthetic and real data demonstrated that BD out- performs the existing index structures for KNN search in high-dimensional spaces.     

WPT-based modal control on distributed structures with MRF-04K damper

The magnetorheological (MR) fluid damper-based semiactive control systems have received considerable attention for protecting structures against natural hazards such as strong earthquakes and high winds. In this paper, a novel modal controller using wavelet packet transform (WPT) is proposed for the vibration control of distributed structures. In the proposed control system, the WPT method is utilized to decompose the acceleration measurement and select the modes containing most of the WPT energy component as the dominant modes. Then, a modal controller is designed to control the dominant modes and the optimal active control force is solved. Finally, Clipped-optimal con- trol law is adopted to determine the voltage applied to each MR damper. A Kalman-filter observer, which estimates the full controlled modal states from local accelerometer feedbacks, is designed for rendering the controller to be more applicable to distributed structures with a large number of degrees of freedom. A numerical example of a stadium roof structure installed with MRF-04K damper is presented. The effectiveness of the controller is evaluated under both Tianjin and El Centro earthquake excitations. The superior performance and adaptability of the controller for versatile loading conditions are demonstrated through the comparison with traditional truncated modal controller.     

Application of dynamic programming to structural repairing strategies

A model of dynamic programming for repairing strategies of concrete structures during a projected service period is proposed,which takes into account the degradation in strength of components and the probability of accidental load.This model takes the safety grade of a structural system as the state variable of repairing strategies,and incorporates economic factors including expected repair cost,property loss due to structure failure,goods and material loss due to structure failure,loss of production interrupt due to structure failure,and inspection cost in decision making.It is found that the optimal repairing strategies are sensitive to the probability of accidental loads as well as the failure costs.The practicality of the model is demonstrated by an example.     

基于变周期采样模型的网络控制系统的随机最优状态反馈控制

本文研究变周期采样的网络控制系统模型的随机最优反馈控制。假设网络诱导延时服从某一个区间的均匀分布,设计一个依赖延时的状态反馈控制器,使得所建立的变周期采样的NCS模型指数均方稳定。利用动态规划思想结合Bellman方程通过优化所给定的性能指标,得到了随机最优反馈控制器设计方法,并通过仿真实例验证了本章提出方法的有效性。     

Application of generalized predictive control in networked control system

INTRODUCTION Networked Control System (NCS) is composed of a central controller and a remote system containing a physical plant, sensors and actuators (Halevi and Ray, 1988; Nilsson, 1998; Walsh et al., 1999a; 1999b; Branicky et al., 2000). The controller and the plant are located at different spatial locations and directly connected through network to form a closed loop control. Fig.1 shows the NCS configuration and the time delay induced by network, where u is the control signal an…     

一类状态可分的随机微分系统的变步长Euler方法

针对一类状态可分的随机微分系统,在文献[9]的变步长Euler方法的基础上,分离出描述慢变状态的微分方程中的快变状态,特殊处理,减少由其引起的误差,建立了新的变步长Euler方法.理论分析和数值实验证明了新方法的优越性.     

基于随机场的动力分析

考虑材料空间多样性,材料性能特性例如弹性模量或波松比被看成随机过程。本文采用随机场的中心点方法,在材料性能特性、几何尺寸、所受载荷被看成随机的情况下,结构振动方程先用Newmark法转化为静力问题。二阶Taylor展开随机有限元被用于结构振动分析,推导简单,易于编程。给出了基于随机有限元的混凝土悬臂梁的振动分析的一个计算实例,对计算结果做了比较,本文提出的方法是有效的。     

Hybrid event based control architecture for tele-robotic systems controlled through internet

A new hybrid event based control architecture for tele-robotic systems controlled through the Internet is proposed in this paper. Different from the traditional event based control method, the new framework does not require every part of the system to be strictly event synchronized. Instead, it allows time referenced control components to be integrated into this framework, which makes it more convenient to develop Internet based control systems. Since there are two reference variables, time and event, in this architecture, how to coordinate these components with different references to keep the stability of the whole system is discussed in detail in this paper. To verify this new idea, an experiment was conducted to control the end effector of a PUMA robot tracking a continuous state trajectory given on-line by the remote operator. Experimental results confirmed the stability of such systems being controlled through the Internet in real-time.