Practical stabilization of a class of uncertain nonlinear systems

In this paper the problem of robust control of a class of nonlinear systems with internal and input channel uncertainties is addressed. The proposed control algorithm reflects the two-level structure of the plant and guarantees the system uniform asymptotic stability with respect to an arbitrary neighbourhood of the nominal system stability point.     

A two-level delimitative and combinatorial algorithm for discrete optimization of structures

In this paper, a two-level delimitative and combinatorial algorithm for a kind of (0,1,2) programming is proposed and applied to discrete optimization of structures. The algorithm generates all combinations in a certain order of magnitude of the function of the objective by using a two-level generating method and eliminates the majority of infeasible or nonoptimum combinations by using a two-level delimitative algorithm, so that computational efficiency is greater. Additionally, a (0,1,2) programming model of discrete structural optimization is established and the local optimum solution can be obtained by using this algorithm, thus it provides a method to judge whether or not the approximate optimum solution obtained by the heuristic algorithm is a local optimum solution.     

基于双线性模型的动态系统优化和参数估计集成方法

针对双线性模型与实际系统之间的差异，提出一种基于双线性模型求解非线性动态系统最优控制的迭代算法。该算法通过重复求解修正的基于双线性模型的优化控制问题和参数估计问题，获得实际系统的最优解。同时提出求解修正的基于双线性模型的优化控制问题的一种新的分解方法，克服了非线性和双线性两点边值问题求解的困难。仿真例子表明该算法的有效性和实用性。     

Performance analysis of two-level structures on finite-precision machines

This paper presents a method for the performance analysis of two-level prediction algorithms when implemented on finite-precision digital machines. The analytical results are compared with an actual system response using simulation results. It is shown that the effect of finite-precision arithmetic is to increase the expected theoretical minimum cost and to slow down the two-level algorithm.     

Two-level twisted preconditionings for parallel computers

A parallel preconditioned conjugate gradient (PCG) algorithm is derived by using a two-level twisted factorization. The algorithm is optimal for a four-processor parallel computer (quadputer). Numerical results obtained on a quadputer with distributed memory are presented.     

一类二层规划问题的区间算法

讨论下层规划问题以最优值反应到上层的二层规划问题的数值解法,其中目标函数和约束函数均为Lipschitz连续函数,构造了二层规划问题目标函数的区间扩张和无解区域删除检验原则,建立了求解二层规划问题的区间算法,并进行了数值实验。理论证明和数值实验均表明算法是可靠和有效的。     

基于两级算法的混沌控制

提出了一种两级算法,可以解决连续混沌系统的最小能量控制问题,首先,给出一个二次目标函数,同时把混沌系统分解为线性部分和非线性部分.上级算法对混沌系统中的非线性部分进行预估,并把整个原系统表为带有常系数的线性系统;下级算法用极小值原理解决这个典型线性二次最优控制问题,并把解返回到上级算法,上级算法根据下级的解对非线性部分重新预估.这样通过两级间不断的信息交换,最终得到混沌系统的最优控制律.该方法不仅实现了对混沌系统的控制,而且在整个控制过程中保证控制能耗为最小.证明了算法的收敛性和闭环系统的稳定性.对统一混沌系统的仿真结果表明了控制策略的有效性.     

Implementation of two-level algorithms using fixed-point arithmetic

The effect of using fixed-point arithmetic in the digital implementation of two-level control algorithms is examined in this paper. Analytical expressions are developed to predict the change in the expected minimum cost and associated matrices. It is shown that there is a favourable match between the analytical predictions and averaged simulation experiments. The use of finite-precision machines increases the expected theoretical minimum cost and makes the two-level algorithm become slow and thus require excessive iterations to converge.     

A hardware implementable two-level parallel computing algorithm forgeneral minimum-time control

A hardware implementable two-level parallel computing algorithm for general minimum-time control is proposed. The minimum-time control problem for a continuous-time system is discretized and transformed into a parameter optimization problem which is large dimensional and nonseparable. The proposed two-level algorithm decomposes this parameter optimization problem into a master-slave problem. The master problem is easily solved by a one-dimensional gradient method, and the slave problem is solved by a parallel computing method which combines recursive quadratic programming with the dual method. The convergence of this iterative two-level parallel computing algorithm under some conditions is proved. On the basis of the VLSI array processor technology, a dedicated hardware computing architecture for realizing this algorithm is presented. The corresponding time complexity, is also analyzed. Simulation of practical problems shows that the algorithm is well suited for real-time application of minimum-time control     

基于三电平的永磁同步电机矢量控制的研究

基于三电平的空间矢量脉宽调制技术的控制方法,对永磁同步电机进行了控制策略研究。采用将三电平空间矢量分解为六个小的两电平空间矢量的方法,转换为对两电平空间矢量的控制,简化了算法。永磁同步电机采用id=0的矢量控制方法,使用了基于电流反馈解耦,在MATLAB2007b/simulink中建立了永磁同步电机三电平SVPWM控制系统的模型,并进行了仿真实验,仿真结果表明永磁同步电机三电平SVPWM控制系统的正确性。     

基于调控流图的定性仿真系统研究

针对复杂系统定性仿真效率较低的问题,在实体语法系统理论的基础上,为改进定性仿真系统,提出调控流图定性仿真系统,利用以三值量空间为基础的五值量空间,在不增加计算量的前提下解决了调控流图定性仿真中的负反馈问题,利用规则、观测变量的二级约束形式降低了系统多途径调节所产生的不确定性,通过变量与多维空间区域的映射实现利用调控流图对时空复杂性进行定性仿真。通过CSTR系统的定性仿真表明,可用于复杂系统的扰动传播途径预测、复杂系统故障诊断等问题,为复杂系统的建模与定性仿真提供了一种新的技术手段。     

Optimal design of truss structures using parallel computing

Parallel design optimization of large structural systems calls for a multilevel approach to the optimization problem. The general optimization problem is decomposed into a number of non-interacting suboptimization problems on the first level. They are controlled from the second level through coordination variables. Thus, the solutions of the independent first-level subsystems are directed towards the overall system optimum. In the present paper, optimal design of truss structures using parallel computing technique is described. In this method, optimization of a large truss structure has been carried out by decomposing the structure into sub-domains and suboptimization tasks. Each sub-domain has independent design variables and a small number of behaviour constraints. The two-level sub-domain optimum design approach is summarized by several numerical examples with speedups and efficiencies of algorithms on message passing systems. It has been noticed that the efficiency of the algorithm for design optimization increases with the size of the structure.     

两能级封闭量子系统任意量子态的最优制备

在分析单量子位的Bloch球面表示的基础上,结合量子门实现量子态幺正演化的量子态调控机制,提出一种针对两能级封闭量子系统任意量子态的最优制备策略．该策略首先建立两能级量子系统及其控制场的模型;然后借助李群李代数．由经典最优控制的思想和约化动力学来获得最优控制,从而达到两能级封闭量子系统任意量子态的最优制备．理论分析与仿真实验表明了该策略的优越性．     

线性时变大系统递阶控制的一种新方法

根据正交函数逼近理论，本文提出了解决时变大系统递阶控制的一种新型逼近算法。文中首先简单介绍了ＰＭＣＰ，同时给出了一些新的研究结果；研究了其在两点边值问题中的逼近解。动态大系统的逼近控制分为二级，第一级是子系统的优化问题，采用ＰＭＣＰ逼近技术解决；第二级为协调级，协调向量也通过ＰＭＣＰ逼近变换求解，这样使问题得到大为简化，不但算法简单，便于计算机运算，而且逼近精度高。数值仿真例子表明了本文提出的算法     

多种燃料锅炉效率曲线的辨识方法

多种燃料锅炉的运行优化是钢铁联合企业节约能源的一个主要方法,但是这种锅炉的效率曲线的辨识却是一个复杂而困难的非线性最小二乘问题。借鉴大系统递阶算法的思想,本文提出了一种新的两级递阶辨识的算法。这种算法通过预估关联量,将非线性最小二乘问题转化为两级线性最小二乘问题。实验的结果证明:这种算法是一种有效的算法。     

Hierarchical computation of decentralized gains for interconnected systems

In this paper, the problem of computing the decentralized gains for linear, interconnected dynamical systems is treated as a constrained optimization problem. A two-level hierarchical computational structure is developed to determine the decentralized gains. At the lower level, two Lyapunov equations are solved whilst a predictive-corrective routine is used at the higher level. Simulation results of two control examples show that our two-level structure needs significantly less computational effort than previous approaches.     

求解包含复杂关联约束的JSSP 的二级嵌套混合算法

作业车间调度问题(JSSP)包含“设备分配”和“工序排序” 2 个相互耦合的子问题,目 前的研究主要集中于工序串行的小规模问题。如果工序之间还存在并行、甚至嵌套等复杂关联 约束,则可行域性状非常复杂,当规模较大时,甚至难以求得可行解。针对以上难点问题,在 分别发挥遗传算法求解“分配问题”和蚁群算法求解“排序问题”的优势基础上,提出了二级嵌套 模型及其基本思路。通过一系列改进策略,如：基于工序的整数编码策略、基于设备类型的多 节点交叉策略、设备类别区间内基因互换的变异策略、基于逆向遍历的可行路径形成策略、基 于最短加工时间的信息素播洒与更新策略等等,构造了集成遗传算法与蚁群算法于同一循环体 的二级嵌套混合算法。针对中等规模问题,分别采用遗传算法、蚁群算法、二级嵌套蚁群算法、 遗传算法与蚁群算法相结合的二级嵌套混合算法,进行了对比试验研究。结果验证了所提算法 的可靠性和优越性,为求解包含复杂关联约束的JSSP 提供了新思路和新方法。     

容器云中基于改进遗传算法的资源分配策略

容器很容易针对Web应用程序提供包装、迁移和配置等服务,近年来已成为研究热点;提出了容器云中基于改进遗传算法的资源分配策略Double-GA;Double-GA是一种包括两个层次的资源分配策略:容器到虚拟机的资源分配和虚拟机到物理主机的资源分配;设计了容器云的两层资源分配的数学模型,以容器云中的整体物理主机能量消耗作为Double-GA策略的目标函数;Double-GA以遗传算法为基础,设计了双染色体的表达方式并处理好了遗传算法的初始化、进化、交叉、变异等操作;真实的实验实例数据结果表明:Double-GA双染色体算法明显优于普通遗传算法GA和递减最好适用算法。     

Hades高可信架构中固定延迟分区实时调度

为了增强不同安全等级的复杂嵌入式安全关键系统的高可信能力,Hades架构以"时空隔离"思想和分区机制为基础,各分区分时共享系统物理资源.针对Hades中分区的实时调度问题,提出一种固定延迟分区调度模型,并采用优先级位图算法设计了分区级和任务级两级调度机制;为了保障分区中所有实时任务的可调度性,对分区中任务组采用单调速率调度和最早截止时间优先2种调度策略,并分别给出任务可调度条件.最后,通过仿真实验进一步验证了该调度模型的有效性.     

减少离散大系统两级镇定控制的保守性

The aim of this paper is to propose a new algorithm for multilevel stabilization of large scale systems. In two-level stabilization method, a set of local stabilizers for the individual subsystems in a completely decentralized environment is designed. The solution of the control problem involves designing of a global controller on a higher hierarchical level that provides corrective signals to account for interconnections effect. The principle feature of this paper is to reduce conservativeness in global controller design. Here, the key point is to reduce the effect of interactions instead of neutralizing them. In fact, unlike prior methods, our idea does not ignore the possible beneficial aspects of the interactions and does not try to neutralize them.