在互联网上进行结构系统协同优化的信息交流与进程调控

 由于异地分布式复杂产品系统的分系统是由不同设计单位分别进行优化设计的。一般说来，这样组集起来的产品系统并不能得到真正优化． 为得到整个分布式结构系统的优化设计就必须进行网络化全局协调优化设计．以互联网的电子邮件为基础，研究了在互联网上进行结构系统全局协调优化设计的信息交流与进程调控技术及其实现途径，并利用VB计算机语言开发了一个实用软件系统． 一个卫星结构系统全局协调优化设计的应用实例表明了分布式结构系统网络化协同优化的必要性和所开发软件的有效性．这项技术对于复杂产品的全球化协同设计具有重要意义．     

Decentralised stabilising controllers for a class of large-scale linear systems

A simple method for computing decentralised stabilising controllers for a class of large-scale (interconnected) linear systems has been developed. Decentralised controls are optimal controls at subsystem level and are generated from the solution of algebraic Riccati equations for decoupled subsystems resulting from a new aggregation-decomposition technique. The method has been illustrated through a numerical example of a large-scale linear system consisting of three subsystems each of the fourth order     

FPGA软硬件协同处理实时图像处理系统

基于PC机图像处理系统实时性不强,DSP+FPGA图像处理系统的成本高、资源利用率低,单纯使用FPGA硬件实现的图像算法类型较为单一,针对这一系列问题,提出了一种基于FPGA软硬件协同处理的实时图像处理系统.采用一片FPGA芯片作为系统的核心,利用CCD相机等采集图像,通过SSRAM将图像缓存,以SOPC为控制核心,协调软硬件共同进行图像处理.易于使用硬件实现的图像处理模块(如滤波、形态学算法、图像校正、边缘检测等)均使用Verilog HDL语言实现,通过SOPC控制这些图像处理模块,实现相应的图像处理功能;而硬件难于实现的部分(如流程控制、复杂的分支判断)则使用SOPC中的CPU来实现.实验表明,系统卖时性强、图像处理速度快、可进行复杂图像算法的运算,同时具有设计简单、应用灵活、成本低的特点.     

磁悬浮轴承－转子系统非线性行为的控制

利用状态反馈法,对磁悬浮轴承 - 转子系统的振动进行控制。通过理论推导,证明在原点附近,可近似地将受控系统分解为两个渐近稳定的子系统之和。借助数值仿真对转子受控前后的运动响应进行分析,以验证该控制方案的有效性。通过比较发现,提出的状态反馈控制方案不但能控制转子的周期运动,而且对该系统的概周期运动和混沌运动也能进行有效控制。     

An inexact fuzzy bi-level programming model for energy–traffic system planning under uncertainty: a case study of Urumqi city,China

In this study, an inexact fuzzy bi-level programming model was developed for regional energy and traffic system management under uncertainty in Urumqi city, China. The energy system and traffic system are important subsystems of regional areas such as cities. The coordinated management of regional subsystems is a difficult problem for regional management. A bi-level programming model is an appropriate and simple method to describe the coordinated management of regional subsystems. The energy and traffic structure adjustment, clean power generation and pollutant emission–reduction targets are designed to support the construction of an environmentally sustainable city in China. Methods of interval parameter programming and bi-level programming were incorporated into the developed model to tackle uncertainties and reflect the features in the system. The environmental impacts of energy and traffic activities and policies were analysed. The results are valuable for supporting the management or justification of the existing energy and traffic policies and schemes under uncertainty.     

基于分析的空调系统运行控制的多目标优化

针对空调系统运行效率低下,且运行过程中子系统之间相互影响、相互制约的问题,本文基于分析方法提出一种空调系统多目标运行优化方法,以提高空调系统整体的运行效率。以某机场航站楼空调系统为研究对象,采用分析方法建立了空调系统的生产结构图,并根据生产结构将空调系统划分为3个子系统。在建立子系统分析模型的基础上,以3个子系统的最小损为优化目标,采用多目标粒子群优化算法(MOPSO)对空调系统的运行参数进行优化。针对某一典型日的运行工况对空调系统进行多目标优化,结果表明:相对于空调系统的原始控制方式,采用多目标运行优化方法可以有效减小空调各个子系统以及整个系统的损,使空调系统的运行效率明显提高,达到了节能的目的。     

略论生态工业系统的运行和控制

根据生态与经济双重存在、持续发展和协调发展三种新思维的时代要求，提出生态工业系统应是由社会、经济和环境三个子系统有机结合而成的三维复合大系统。在此基础上，论述了系统的运行机制，即通过子系统内部的持续性发展与子系统之间的协调性发展来促使大系统整体的进化。最后，探讨通过二级递阶控制和分散控制的综合来保证系统的顺利进行。     

System repairs: When to perform and what to do

In this paper an indicator is used that reflects the “state” of a system as a function of the ages of the (groups of) subsystems of which it consists. The contribution of the ages of the subsystems to the state of the system is defined by their weights. The indicator can be interpreted as the virtual age of the system, and can therefore be used to define age-reduction factors of different types of repair in a virtual age or age-reduction process. The state indicator is used as the time scale in a proportional intensity model. In this way, the joint impact of different repair strategies and covariates on the system failure intensity can be evaluated. This relationship is then used to address the question of which subsystems to replace whenever a system comes in for repair and when to set the preventive inspection/repair interval, in order to minimize the expected costs per unit time until the next inspection and/or repair. A numerical and a practical example are given.     

时域稳定的基础频响连续有理近似参数识别方法EI北大核心CSCD

采用连续有理近似函数描述基础时域动力模型是土-结动力相互作用时程分析的重要方法。该近似函数的稳定性和精度决定了土-结相互作用系统时域分析的稳定性和精度。目前,连续时间有理近似函数的参数识别方法无法同时确保精度、稳定性和计算效率。该文基于线性系统控制理论,将有理近似函数分解为一系列一阶和二阶子系统的组合,并通过各子系统的稳定条件提出了被识别参数的理论稳定边界。基于此,利用遗传算法和序列二次规划算法建立了时域稳定的连续有理函数参数识别方法。不同基础频响函数数值仿真结果表明:对于简单函数,该文方法与既有方法均可保持高精度,但该文方法在确保稳定性的同时可以提高近35%的计算效率。对于复杂函数,采用高阶有理函数时,该文方法用时仅为既有方法的25%,同时精度大于95%。证明了该方法可以在保证函数稳定性与拟合精度的同时提高了计算效率,从而使得连续有理近似函数适用性更好。     

Stabilisation of a class of stochastic bilinear interconnected systems by suboptimal decentralised feedback controls

A computationally simple method has been suggested for decentralised stabilisation of a class of stochastic bilinear interconnected systems by optimal feedback controls at subsystem levels, appropriately designated “Suboptimal Decentralised Feedback Control”. The proposed method makes use of an aggregation-decomposition technique based on algebraic Riccati equations. The method has been illustrated through a numerical example of the stochastic bilinear interconnected system consisting of three subsystems, each of second order.     

Multidisciplinary Design Optimization with Quasiseparable Subsystems

Numerous hierarchical and nonhierarchical decomposition strategies for the optimization of large scale systems, comprised of interacting subsystems, have been proposed. With a few exceptions, all of these strategies lack a rigorous theoretical justification. This paper focuses on a class of quasiseparable optimization problems narrow enough for a rigorous decomposition theory, yet general enough to encompass many large scale engineering design problems. The subsystems for these problems involve local design variables and global system variables, but no variables from other subsystems. The objective function is a sum of a global system criterion and the subsystems' criteria. The essential idea is to give each subsystem a budget and global system variable values, and then ask the subsystems to independently maximize their constraint margins. Using these constraint margins, a system optimization then adjusts the values of the system variables and subsystem budgets. The subsystem margin problems are totally independent, always feasible, and could even be done asynchronously in a parallel computing context. An important detail is that the subsystem tasks, in practice, would be to construct response surface approximations to the constraint margin functions, and the system level optimization would use these margin surrogate functions. The purpose of the present paper is to present a decomposition strategy in a general context, provide rigorous theory justifying the decomposition, and give some simple illustrative examples.     

Towards an approach of synthesis,validation and implementation of distributed control for AMS by using events ordering relations

We study distributed control synthesis and validation for automated manufacturing systems (AMS) in the framework of supervisory control theory. To reduce the size of the control problem, we view an AMS as comprised of asynchronous subsystems which are coupled through imposed logical Boolean specifications. The principle of the distributed control approach is the decomposition of the global monolithic control action into local coordinated control strategies for the individual subsystems. Owing to its importance in a distributed scheme, the order in which events occur arouses interest. By extending our previous results, we develop a set of rules of events precedence ordering, under which the control strategy via decomposition promises the subsystems synchronisation and coordination. We show how these rules contribute to reduce the size of the controller models used in the verification/validation and implementation steps. The effectiveness of the proposed approach is demonstrated by means of an industrial AMS example.     

Survivability of systems under multiple factor impact

The paper considers vulnerable multi-state series-parallel systems operating under influence of external impacts. Both the external impacts and internal failures affect system survivability, which is determined as the probability of meeting a given demand. The external impacts are characterized by several destructive factors affecting the system or its parts simultaneously.In order to increase the system's survivability a multilevel protection against the destructive factors can be applied to its subsystems. In such systems, the protected subsystems can be destroyed only if all of the levels of their protection are destroyed.The paper presents an algorithm for evaluating the survivability of series-parallel systems with arbitrary configuration of multilevel protection against multiple destructive factor impacts. The algorithm is based on a composition of Boolean and the Universal Generating Function techniques.Illustrative examples are presented.     

Modelling dependable systems using hybrid Bayesian networks

A hybrid Bayesian network (BN) is one that incorporates both discrete and continuous nodes. In our extensive applications of BNs for system dependability assessment, the models are invariably hybrid and the need for efficient and accurate computation is paramount. We apply a new iterative algorithm that efficiently combines dynamic discretisation with robust propagation algorithms on junction tree structures to perform inference in hybrid BNs. We illustrate its use in the field of dependability with two example of reliability estimation. Firstly we estimate the reliability of a simple single system and next we implement a hierarchical Bayesian model. In the hierarchical model we compute the reliability of two unknown subsystems from data collected on historically similar subsystems and then input the result into a reliability block model to compute system level reliability. We conclude that dynamic discretisation can be used as an alternative to analytical or Monte Carlo methods with high precision and can be applied to a wide range of dependability problems.     

Diagnosis Modelling for Dependability Assessment of Fault‐Tolerant Systems Based on Stochastic Activity Networks

The growing demand for safety, reliability, availability and maintainability in modern technological systems has led these systems to become more and more complex. To improve their dependability, many features and subsystems are employed like the diagnosis system, control system, backup systems, and so on. These subsystems have all their own dynamic, reliability and performances and interact with each other in order to provide a dependable and fault‐tolerant system. This makes the dependability analysis and assessment very difficult. This paper proposes a method to completely model the diagnosis procedure in fault‐tolerant systems using stochastic activity networks. Combined with Monte Carlo simulation, this will allow the dependability assessment by including the diagnosis parameters and performances explicitly. Copyright © 2014 John Wiley & Sons, Ltd.     

剪式可展机构非线性动力学分析的子系统方法

剪式可展机构由相互耦合的闭环子系统构成,针对这种拓扑结构的多体系统,给出了基于子系统模型的非线性动力学建模方法。将剪式可展机构分解为多个简单子系统,推导出子系统等效质量矩阵和等效力向量,通过子系统间的反向递推求解整个多体系统的等效质量矩阵和等效力向量,从而将大规模运动方程转化为简单运动方程,缩减了求解规模。所建立的子系统模型可以重复使用,且当子系统的结构或子系统个数发生变化时,便于整个剪式可展机构模型的修改,易于程式化建模。与传统方法的对比验证了该方法的正确性。     

异步切换下切换系统的动态输出反馈保成本控制

作为一类重要的混杂系统,切换系统由若干个子系统以及一个协调各子系统之间切换的切换信号构成,在自然科学、工程控制和社会系统等方面有着广泛的应用。在对切换系统的控制问题进行研究时,一般假设子系统和控制器同步运行。然而,在实际工程控制中,控制器的切换相对于子系统的切换存在切换时延,从而产生异步切换。因此,对异步切换下的切换系统研究是十分必要的。针对一类异步切换下切换系统的动态输出反馈保成本控制问题进行了研究。报告了切换系统的研究现状以及异步切换下切换系统的最新研究成果。利用分段李雅普诺夫函数法和平均驻留时间法,得到了使得异步切换下的闭环切换系统稳定的动态输出反馈控制器存在的充分条件。从线性矩阵不等式的角度,提出了异步切换动态输出反馈保成本控制器设计方案,并给出成本上界的优化方法。最后,通过一个数值算例说明了提出的方法的有效性。     

H－S法波前探测的高速图象采集系统

自适应光学系统中有两种方法用于测定波前的局部斜率：剪切干涉测量法和哈特曼法（以下简称Ｈ－Ｓ法）。由于Ｈ－Ｓ法运用较简单的光学系统，无需任何活动组件，具有较高的光效率，并能很好地用于探测器阵列，因此它更普遍地用于自适应光学系统中。本文介绍了一种应用于Ｈ－Ｓ法波前探测的高速图象采集系统，提出了应用本图象采集系统解决高帧频探测器阵列与数据处理机之间的同步协调的方法。     

Survivability of series–parallel systems with multilevel protection

In this paper, we consider vulnerable systems which can have different states corresponding to different combinations of available elements composing the system. Each state can be characterized by a performance rate, which is the quantitative measure of a system's ability to perform its task. Both the impact of external factors (attack) and internal causes (failures) affect system survivability, which is determined as the probability of meeting a given demand.In order to increase the system's survivability a multilevel protection can be applied to its subsystems. In such systems, the protected subsystems are destroyed by external impacts only if all of the levels of their protection are destroyed.The paper describes an algorithm for evaluating the survivability of series–parallel systems with arbitrary configuration of multilevel protection. The algorithm is based on a composition of Boolean and the Universal Generating Function techniques. The adaptation of the algorithm for numerical implementation is suggested.Illustrative examples are presented.     

异步切换下切换时变时滞系统的保成本控制

切换系统是一种重要的混杂系统,由若干子系统及决定子系统之间切换的切换信号组成。在工程应用中,控制器切换与子系统的切换会存在时延,即异步切换。研究了异步切换下的时变时滞系统的保成本控制问题,利用分段李雅普诺夫函数法和平均驻留时间法,得到保成本控制器存在的充分条件,并从线性矩阵不等式的角度,设计了一个异步切换保成本控制器,使得系统具有鲁棒性能。最后,给出了一个数值例子验证提出的方法的有效性。