双线性系统可控性综述

双线性系统是一类特殊的非线性系统,广泛存在于现实世界中,如工程、经济、生物、生态等领域,被认为是最接近于线性系统的非线性系统．对双线性系统的研究已历经了近半个世纪. 作为系统最基本的属性,双线性系统可控性的研究一直以来是热点和难点.本文分别对连续双线性系统可控性和离散双线性系统可控性进行讨论, 综述了双线性系统可控性的研究.特别地,报告了近来对离散双线性系统可控性研究的新成果.最后,例举了一些可控的双线性系统例子.     

可信系统性质的分类和形式化研究综述

计算机系统被应用于各种重要领域,这些系统的失效可能会带来重大灾难.不同应用领域的系统对于可信性具有不同的要求,如何建立高质量的可信计算机系统,是这些领域共同面临的巨大挑战.近年来,具有严格数学基础的形式化方法已经被公认为开发高可靠软硬件系统的有效方法.目标是对形式化方法在不同系统的应用进行不同维度的分类,以更好地支撑可信软硬件系统的设计.首先从系统的特征出发,考虑6种系统特征:顺序系统、反应式系统、并发与通信系统、实时系统、概率随机系统以及混成系统.同时,这些系统又运行在众多应用场景,分别具有各自的需求.考虑4种应用场景:硬件系统、通信协议、信息流以及人工智能系统.对于以上的每个类别,介绍和总结其形式建模、性质描述以及验证方法与工具.这将允许形式化方法的使用者对不同的系统和应用场景,能够更准确地选择恰当的建模、验证技术与工具,帮助设计人员开发更加可靠的系统.     

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.     

类广义Lorenz系统的广义同步

应用广义Lorenz标准型研究了包括广义Lorenz系统、双曲型广义Lorenz系统以及Liu-Liu-Liu-Liu系统在内的类广义Lorenz系统的广义同步化问题．利用映射将一大类三阶二次混沌系统变换为广义Lorenz标准型,设计控制器使变换后的系统达到完全同步,进而使变换前的系统实现广义同步．将该方法分别用于拓扑等价和不等价的两个系统,通过数值仿真,发现结果和理论分析相符,从而表明了该方法的有效性．     

混杂系统的一致输入输出对状态稳定性

混杂系统的输入输出对状态稳定性是混杂控制系统领域极富挑战性的课题之一. 为了观测混杂系统的状态,本文提出了一类混杂系统的一致输入输出对状态稳定的充分条件,分析了混杂系统的一致输入输出对状态稳定性、光滑Lyapunov函数存在性和状态模估计器存在性三者之间的关系. 借助状态模估计器将混杂系统化为受扰动系统,获得了受扰动系统一致输入输出对状态稳定性的结果,并进一步证明了混杂系统的一致输入输出对状态稳定性.     

合成信息系统与子信息系统的属性特征

数据库的合成和分解在实际应用中是一个很重要的问题,它所对应的数学模型就是信息系统的合成与分解,该文给出了对象合成信息系统、属性合成信息系统、对象子信息系统及属性子信息系统的定义,讨论了合成信息系统、子信息系统与原信息系统等属性特征之间的关系。     

各向同性线性系统理论研究综述

各向同性线性系统作为一类特殊的线性系统,不仅具有广泛的应用背景,还具备许多一般线性系统不具有的特殊性质.鉴于此,系统地归纳总结各向同性线性系统的特点,特别是这类系统与其对应的复系数线性系统之间的关联;此外,讨论对各向同性线性系统设计各向同性反馈的必要性,并以航天器姿态控制系统为例介绍各向同性线性系统的具体应用实例;结合几类常见的可用各向同性线性系统描述的工程控制系统,对现有的相关结果进行归纳和介绍;最后对各向同性线性系统进一步的研究方向进行简单的展望.     

Effects of Adoption and Assimilation of Enterprise Systems on Business Performance: A Senior Executive’s Perspective

Drawing from the institutional theory and resource-based view, we investigated the effects of a firm’s activities and levels of enterprise systems adoption and the effectiveness of the enterprise systems in supporting the firm (enterprise systems assimilation) on business performance. Empirical results suggest that institutional forces and IS resources significantly influence the enterprise systems adoption, which indirectly impacts the enterprise systems assimilation. Further, the enterprise systems adoption significantly influences business performance, and the enterprise systems assimilation mediates the effect of the enterprise systems adoption on business performance.     

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.     

知识库系统和语言的演变

引言 Prolog作为一个良好的Al语言已经得到广泛接受,市场上已经有多种Prolog产品(包括Prolog机).但是,Prolog不能有效地管理持久数据且“每次一个元组”的求值方式不适用于数据密集型应用(如:CAx、CIMS、专家系统、……)。另一方面,数据库管理系统(DBMs)能够有效安全地管理大容量数据.但不能处理递归,而递归是上述基于知识系统的基本能力。因此,研制同时具有Prolog和DBMS能力的新型数据系统就成为必要。     

A Coalgebraic Representation of Reduction by Cone of Influence

The Cone of Influence Reduction is a fundamental abstraction technique for reducing the size of models used in symbolic model checking. We develop coalgebraic representations of systems as composites of state transition maps and connectors. These representations include synchronous systems, asynchronous systems, asynchronous systems with synchronization by channels, and those with shared variables, probabilistic synchronous systems and so on. We schematically show the cone of influence reduction using these coalgebraic representations, which give a unified framework for providing the technique for various kinds of systems.     

Rigid formation control of double-integrator systems

In this paper, we study rigid formation control systems modelled by double integrators. Two kinds of double-integrator formation systems are considered, namely formation stabilisation systems and flocking control systems. Novel observations on the measurement requirement, the null space and eigenvalues of the system Jacobian matrix will be provided, which reveal important properties of system dynamics and the associated convergence results. We also establish some new links between single-integrator formation systems and double-integrator formation systems via a parameterised Hamiltonian system, which, in addition, provide novel stability criteria for different equilibria in double-integrator formation systems by using available results in single-integrator formation systems.     

On the quasi-balanceable class of linear quantum stochastic systems

This paper is concerned with the characterization of the quasi-balanceable class of linear quantum stochastic systems (i.e., systems that can be approximated via the recently proposed quasi-balanced truncation method). It has previously been shown that the quasi-balanceable class of systems includes the class of completely passive systems. In this work, we refine the previously established characterization of quasi-balanceable systems and show that the class of quasi-balanceable systems is strictly larger than the class of completely passive systems. We derive a novel characterization of completely passive linear quantum stochastic systems solely in terms of the controllability Gramian of such systems. Exploiting this result, we prove that all linear quantum stochastic systems with a pure Gaussian steady state (active systems included) are all quasi-balanceable, and establish a new complete parameterization for this important class of systems. Examples are provided to illustrate our results.     

一类混沌系统的状态观测与控制

基于混沌系统运动的有界性,使得不依赖于对象模型的扩张状态观测器可用于一类混沌系统的状态观测。只要扩张状态观测器充分观测到混沌系统的状态,自抗扰控制器就可以控制混沌系统,几个混沌数值仿真表明了扩张状态观测器和自抗扰控制器可有效地用于混沌系统的观测和控制。     

Model-driven performance prediction of systems of systems

Systems of systems exhibit characteristics that pose difficulty in modelling and predicting their overall performance capabilities, including the presence of operational independence, emergent behaviour, and evolutionary development. When considering systems of systems within the autonomous defence systems context, these aspects become increasingly critical, as constraints on the performance of the final system are typically driven by hard constraints on space, weight and power. System execution modelling languages and tools permit early prediction of the performance of model-driven systems; however, the focus to date has been on understanding the performance of a model rather than determining whether it meets performance requirements, and only subsequently carrying out analysis to reveal the causes of any requirement violations. Moreover, such an analysis is even more difficult when applied to several systems cooperating to achieve a common goal—a system of systems. In this article, we propose an integrated approach to performance prediction of model-driven real-time embedded defence systems and systems of systems. Our architectural prototyping system supports a scenario-driven experimental platform for evaluating model suitability within a set of deployment and real-time performance constraints. We present an overview of our performance prediction system, demonstrating the integration of modelling, execution and performance analysis, and discuss a case study to illustrate our approach.     

混合系统改进的仿真时钟等步长同步方法及性能评价研究

通过对一类混合系统仿真中的连续系统、离散事件系统及推理决策系统各自仿真时钟的分析,得出了推理决策系统仿真依赖于其两个系统的结果,继而提出了用其中的离散事件 系统仿真时钟云同步具有等步长策略的连续系统仿真时钟改进的等步长方法,并给出了相应的软件实现方法与性能评价准则,解决了该类混合记真时钟的同步问题,减少了仿真误差,从而为该类混合系统的仿真提供理论依据。     

一类滞后型时变广义系统解的稳定性

滞后广义系统解的稳定性的研究与非奇异系统或不带滞后的广义系统解的稳定性研究均有不同。为了解决所遇到的新困难,一种稳定性的新概念被提出,同时,通过Lyapunov函数方法,两个稳定性判定定理得以建立。这些结果被应用于线性系统,得到了一个关于线性系统稳定性判定的很有价值的结果。     

Reliability and Mean Time to Failure of Unrepairable Systems With Fuzzy Random Lifetimes

In practice, the lifetimes of unrepairable systems contain both randomness and fuzziness. So it is appropriate to assume the lifetimes of systems to be fuzzy random variables. In this paper, the definitions of reliability and mean time to failure (MTTF) of unrepairable systems with fuzzy random lifetimes are given, respectively. Then basic mathematical models of unrepairable systems with fuzzy random lifetimes are established. Furthermore, the reliability and MTTF of series systems, parallel systems, series-parallel systems, parallel-series systems, and cold standby systems are discussed, respectively. Finally, some numerical examples are presented to illustrate how to calculate the reliability and MTTF of unrepairable systems with fuzzy random lifetimes.     

线性时变广义系统的能控性与能观性问题

讨论了线性时变系统和线性时变广义系统的两个基本问题, 得到了两种判定时变系统能控性与能观性的必要条件, 该判定条件只依赖于系统矩阵A(t)和输入矩阵B(t), 不必计算系统的系统状态转移矩阵, 使得判别时变系统能控性与能观性易于实现. 说明了本文结论是线性定常系统相应结论的自然扩展. 对进一步深入研究时变系统和时变广义系统具有实际启发作用.     

Synchronization of a class of nonlinear network flow systems

In this paper, we consider the synchronization of a class of nonlinear network flow systems. Motivated by air distribution problem in air conditioning and mechanical ventilation (ACMV) systems, we propose a class of coupled nonlinear multi‐agent systems that can model a wide class of network flow systems, including air flow in ACMV systems, water flow in irrigation systems, traffic flow in transportation systems, and so on. Then we consider the synchronization problem for the class of nonlinear multi‐agent systems and propose cooperative controllers for the system. Based on graph theory, we derive conditions on the initial values of the state and the control input such that synchronization can be achieved. An application to air ventilation is provided to demonstrate the effectiveness of the cooperative controllers. Copyright © 2015 John Wiley & Sons, Ltd.