含两类时滞的线性系统的故障诊断及故障可诊断性*

研究同时含有状态时滞和测量时滞的时滞系统的故障诊断方法及故障的可诊断性问题,提出一种同时对状态时滞和测量时滞进行变换的无时滞变换方法,并提出一种新的故障诊断器的构造方法,同时给出时滞系统的故障可诊断性的判据。首先通过提出一种同时对状态时滞和测量时滞进行转换的无时滞转换方法,将时滞系统转换成无时滞的系统;然后将故障诊断问题转换为状态观测问题,给出并证明了故障可诊断性的判据;最后通过构造一种不利用残差体现故障的新的故障诊断器,实现了故障的实时诊断并解决了故障诊断器的物理不可实现问题。仿真实例验证了该方法的可行     

具有时滞的双向联想功能的神经网络模型的稳定性

本文利用Razumikhin条件和具体的Lyapunov函数,讨论了时滞BAM模型平衡点的稳定情况,得到了在时滞适当小时,时滞BAM模型与无时滞BAM模型具有相同的渐近稳定性.     

时滞反馈Lorenz系统的混沌特性及其电路实现

在研究时滞反馈Lorenz系统时, 关键是模拟时滞环节的实现. 由于数字时滞电路存在模数转换精度的问题,所以采用数字时滞电路的时滞反馈Lorenz系统容易产生不真实的电路现象. 本文研究了一种用模拟电路实现的时滞电路, 并将其加入到Lorenz系统中构成时滞状态反馈Lorenz系统. 通过对系统的数字仿真和模拟电路的制作和实验, 验证了实验和仿真的结果完全相符, 表明了时滞可以使Lorenz系统产生更复杂拓扑结构的吸引子.     

一类小车倒立摆的起摆稳摆时滞控制研究

主动控制中不可避免地存在时滞现象.本文研究了一级小车倒立摆由起摆到稳摆的时滞切换控制,包括非线性时滞起摆控制和线性时滞串级PD控制两种控制方法.为分析时滞对系统瞬态时域性能的影响,本文使用含时滞的线性表达式对特定运动时刻的Lyapunov函数导数进行近似,得到了时滞影响系统能量输入的简单判别式,发现时滞可优化非线性起摆控制阶段的能量输入.同时,使用定积分法分析了稳摆阶段的稳定性,得到了时滞的稳定性区间.针对本文所研究的小车倒立摆系统,综合起摆阶段和稳摆阶段的时滞取值范围,以引入适当的时滞,可以同时实现优化瞬态时域特性和稳定性的效果.     

基于观测器的离散时滞系统的故障诊断

研究含有测量时滞的线性离散系统的故障诊断问题,提出一种测量时滞的无时滞转换方法和基于降维状态观测器而不利用残差体现故障的故障诊断方法.首先通过构造一个含有故障状态的增广系统和进行测量时滞的无时滞转换,将时滞系统的故障诊断问题转化为无时滞增广系统的状态观测问题;然后给出了其诊断误差能按预先指定的指数速率趋于零的故障诊断器的设计方法.仿真算例验证了该方法的可行性和有效性.     

带有时滞的随机区间Hopfield神经网络的指数稳定性

讨论了带有可变时滞的随机区间Hopfield神经网络的指数稳定性, 利用It^o公式和Lyapunov函数, 得到了几个关于其指数稳定时滞无关和时滞相关的充分性条件, 推广了现有文献中关于定常时滞随机神经网络及其确定形式的许多结果.     

利用提升-预估法设计离散时间时滞线性系统的预见控制器

研究一类既有状态时滞又有输入时滞的离散时间线性系统的预见控制问题.分别使用离散提升技术和变量替换法将系统中的状态时滞和输入时滞消掉,得到一个无时滞的系统.在此基础上,使用预见控制理论和状态预估法得到一个带有状态时滞补偿、输入时滞补偿和参考信号预见补偿的控制器.针对不同的时滞使用不同的方法进行消除,有效地降低了增广系统的维数.最后,通过一个数值算例验证了所提出设计方法的有效性.     

时滞系统的鲁棒稳定性分析

研究时滞系统的时滞独立稳定性和时滞相关稳定性问题。基于Ｂａｒｂａｌｅｔ引理,得到了一类检验线性时滞系统稳定性的简单条件。进一步研究了一类含非线性不确定性时滞系统的鲁棒稳定性问题。数值例子表明,所得到的结果比已有结果的保守性小。     

基于H∞控制的时滞系统故障诊断

应用H∞控制技术,探讨具有不确定性输入以及输入时滞系统的故障诊断（FD）问题.该文提出的算法能够诊断时滞系统的执行器故障和传感器故障.首先介绍了时滞系统的H∞控制技术,给出了时滞系统H∞控制器存在的充要条件.然后考虑含有故障的时滞系统,设计了故障诊断滤波器,将故障诊断滤波器与原系统组成增广系统,增广系统中包含时滞系统的执行器故障和传感器故障.最后,应用H∞控制技术,对增广系统设计故障诊断系统,能够诊断出时滞系统的执行器故障和传感器故障.     

基于LMI方法的时滞分布参数控制系统的镇定

针对常时滞、多个常时滞及多个变时滞的分布参数控制系统,提出一种与现有研究分布参数控制系统不同的方法．该方法通过构造平均Lyapunov函数,利用LMI和矩阵不等式知识,在只要求系统本身所固有的系数是负定矩阵的条件下,给出了所研究的分布参数系统镇定的充分条件．当模型中时滞为常时滞时,所得的充分条件与时滞无关;当模型中时滞为变时滞时,所得模型的镇定准则依赖于时滞．此外,该方法一个显著优点是所获得的条件容易检验,因而易于应用．     

基于不确定理论的复杂体系优化方法研究

为研究复杂体系的优化方法,首先针对复杂体系的三个发展阶段,提出了三类优化问题;其次通过研究体系结构、体系能力和体系效能之间的内在关系,给出了体系优化的思路,建立了以体系效能为优化目标的复杂体系优化模型;接着利用模糊集理论与证据理论讨论了体系能力评估中定性信息的定量化问题,探索了新的体系能力评估方法,并基于体系效能仿真,采用粗糙集理论建立了求解体系能力权值因子的算法;最后给出了求解优化模型的方法.所提出的优化方法为复杂体系优化问题提出了一种新思路.     

Control for smart systems: Challenges and trends in smart cities

There have been tremendous developments in theories and technologies in control for smart systems. In this paper we review applications to various systems that are crucial for the future of smart cities, for example enterprise and manufacturing systems, transportation systems, energy systems, and data centres. Beyond discussing the existing technological trends and the methodological approaches developed so far for managing and controlling such systems, we also provide visions on the future challenges for these systems in these various aspects.     

具有输入饱和的非线性系统的分散输出控制

考虑了一类具有输入饱和的非线性组合大系统的镇定问题。利用李雅普诺夫稳定理论和矩阵理论研究了这类非线性组合大系统的分散输出镇定问题,并给出了一种分散输出镇定控制器的设计。考虑了另一类具有输入饱和的非线性相似组合大系统,由于相似组合系统的结构特点,给出了简洁的分散输出镇定的条件。     

闭环系统故障诊断技术综述

本文着眼于闭环环境下动态系统中的故障诊断问题.介绍了目前闭环系统故障诊断的研究意义, 特别关注了开闭环故障诊断的不同,并概述了现有的闭环系统故障诊断方法. 通过仿真实验比较了典型开环系统和闭环系统中故障诊断的不同性能.最后探讨了闭环系统故障诊断研究中 亟待解决的问题以及未来可能的研究方向.     

A comparison of four microcomputer operating systems

This article describes a comparative study of four operating systems for IBM-PC compatible microcomputers. The assessment concentrated on the suitability of the operating systems for use in real-time applications, and on their use as development environments for real-time systems. The study evaluated the predictability and the performance of the operating systems in several areas critical in real-time systems by using comparative benchmarks. In addition, a small-scale simulation of a process control system was developed for each of the systems. The operating systems that were studied were UNIX, OS/2, QNX and FlexOS. These operating systems represent a broad spectrum of systems from general purpose operating systems to small, specialized real-time operating systems. The details of the evaluation process are given and a summary of the results is presented.     

Modeling and Identification of Multirate Systems

Multirate systems are abundant in industry; for example, many soft-sensor design problems are related to modeling, parameter identification, or state estimation involving multirate systems. The study of multirate systems goes back to the early 1950s, and has become an active research area in systems and control. This paper briefly surveys the history of development in the area of multirate systems, and introduces some basic concepts and latest results on multirate systems, including a polynomial transformation technique and the lifting technique as tools for handling multirate systems, lifted state space models, parameter identification of dual-rate systems, how to determine fast single-rate models from dual-rate models and directly from dual-rate data, and a hierarchical identification method for general multirate systems. Finally, some further research topics for multirate systems are given.     

SOCIAL SYSTEMS THEORY AND PRACTICE: THE NEED FOR A CRITICAL APPROACH

Much of the success of science in explaining, predicting and controlling natural systems can be attributed to the well understood methods that exist for producing and testing theory in the natural sciences. The successful development of social systems science is similarly likely to depend on the elucidation of methods of inquiry suitable to the systems of its concern. Unfortunately the successful methods employed by natural scientists cannot be simply taken over and used in social systems science. Systems scientists who attempt this, risk operating with wholly inappropriate tools when dealing with social systems. Alternative methods of inquiry have been developed in the “soft” systems tradition which are more appropriate for use in relation to one large class of social systems. However, there are many social systems for which even these soft systems approaches are inappropriate. For such social systems there is a need for a more radical and critical approach to producing and verifying social systems science. This paper seeks to demonstrate the need for a critical approach in relation to one class of social systems and shows how only this kind of approach can take account of the special characteristics of this category of social system.     

Crisis IT design implications for high risk systems: systems,control and information propositions

The systems view is presented as a complement to the more traditional scientific approach to help reduce and mitigate risk in high risk systems. Implications for this systemic approach are described, principally in the areas of control and information. Most generally, we investigate how high risk systems use information to maintain control, and how IT systems should be designed to support this activity. Two variations in the systems view – the objective and constructive – are distilled and compared, and for each, the implications for crisis IT systems design are discussed. The limitations of the two variations of the systems view are presented, as is a brief annotated bibliography for further reading about the systems view.     

一种实值属性信息系统的粗集约简方法

本文研究应用粗集理论对实值信息系统属性进行约简的方法，对实值属性信息系统进行约简的根本问题是如何对实值属性离散化，通过对离散化方法与属性约简的关系进行研究，提出实值属性离散化的一种自动确定属性类别的方法，并结合粗集理论给出了对实值属性信息系统约简的算法，用所提出的算法进行了实验，并给出了实验结果。     

含未知输入的广义系统的状态与输入估计

研究了含未知输入的广义系统的输入解耦观测器设计问题. 在系统脉冲能控的条件下通过系统输入-状态对的非奇异变换, 把此问题等价地转化为正常状态空间系统的相应问题. 用大家熟知的方法设计正常状态空间系统的观测器, 从而得到广义系统的输入解耦观测器. 然后用广义系统的观测器状态和系统输出的线性组合渐近估计系统的状态与未知输入.