受控离散事件过程的一种代数分析方法

本文在文１－３的基础上，提出了受控离散事件过程的一种代数分析方法，弥补了Ｒａｍａｄｅ和Ｗｏｎｈａｍ的理论对具体系统的应用缺乏可操作性的缺陷，使得对ＣＤＥＰ动态过程的分析变得更为直观，同时也使控制器的设计过程更具可操作性。     

驱动升级公告

ＥＣＳ精英 Ｋ７Ｓ６Ａ Ｖ１．０Ｘ主板最新ＢＩＯＳ ０１／１５／２００２版新增支持 Ａｔｈｌｏｎ ＸＰ ２０００＋处理器，增加了 ＵＳＢ唤醒功能，修正了在安装Ｗｉｎ９８时，ＵＳＢ键盘不能使用热键的问题［１８２Ｋ］ＥＣＳ精英 Ｐ６ＶＸＡＴ Ｖ１．０Ｘ主板最新 ＢＩＯＳ１．０ｂ版修正了与 Ｔｕｌａｔｉｎ１．２Ｇ ＣＰＵ的兼容性问题 ［２０２Ｋ］下载：ｗｗｗ．ｅｃｓ．ｃｏｍ．ｔｗＡｓｕｓ华硕Ｐ４５３３３主板（无板载网路及声音芯片）最新ＢＩＯＳ １００３Ｃ版［１７９Ｋ］华硕Ａ７Ｖ２６６－Ｅ／ＡＡ主板（无板载网络及声音…     

银河－Ⅱ并行程序设计环境

本文阐述的银河－Ⅱ并行程序设计环境ＫＤ－ＰＡＳＴＥ以相关分析理论为基础［１］，充分挖掘应用程序的向量成分，并同时对程序的微任务化［１］进行了探索。该系统功能齐全，使用方便，可移植性强。     

一种通用的全局寻优演化算法-自适应进化规划

１．引 言 Ｄａｒｗｉｎ的进化论所描述的“物竞天演，优胜劣汰”的自然进化过程，实际上是描述了一种强壮的搜索、竞争与优化机理．科学家们用数学方式将此过程进行简化模拟，形成了一类具有鲜明特色的优化方法，即演化算法［１］.进化规划（Ｅｖｏｌｕｔｉｏｎａｒｙ Ｐｒｏｇｒａｍｍｉｎｇ－ＥＰ）［１，２］便是其中的一个分支．一般ＥＰ算法常被描述为求解实值函数极小化（极大化）问题 （Ｐ）ｍｉｎ（ｍａｘ）Ｆ（ｘ）：Ｒｎ→Ｒ，（１） ｘＲｎ且在人工智能、神经网络、自适应控制以及众多的工程应用领域显示了解决复杂问题的特别能…     

无内部冲突满足P3的无α环的数据库模式分解（Ⅰ）：分解的基本理论

文中在文献［１］、［２］、［３］讨论的基础上，讨论了数据库模式无内部冲突，但在最小归并依赖集Ｄ中存在弱右部或弱左部冲突时分解的性质和理论．为无内部冲突的满足Ｐ３的无α环的数据库模式分解算法设计提供了基础．     

迎风紧致格式与热流计算

１．引 言 众所周知,ＴＶＤ格式是能够高质量地捕捉激波的方法,但在计算粘性绕流时许多ＴＶＤ格式数值耗散太大,不能正确模拟粘性流动,因而无法正确计算热流值．文献［３］指出,采用高精度格式可适当放松对网格雷诺数的要求,因此发展三阶或三阶以上的格式是需要的．文献［４］研究了迎风紧致群速度控制格式（ＵＣＧＶＣ格式）在 Ｅｕｌｅｒ方程中的应用,提高了对激波的分辨率,优于通常二阶精度ＴＶＤ格式．本文在文献［４］的基础上给出了利用迎风紧致格式求解ＮＳ方程．它是ＵＣＧＶＣ格式在粘性流计算中的推广．对于方程中的无粘…     

MP3随身听大联唱──九款MP3播放机对比性评测报告

我们都知道在电脑上可以用软件来播放的音乐格式有很多种,而ＮＰ３无疑是当今最流行的的音频压缩格式。ＮＦ３是ＭＦＥＧＡｕｄｉｏＬａｙｅｒ３的缩写,ＭＰＥＧ压缩格式是由运动图像专家组（ＭｏｔｉｏｎＰｉｃｔｕｒｅＥｘｐｅｒｔｓＧｒｏｕｐ）制定的关于影像和声音的一组标准,其中ＭＰ３就是为了压缩声音信号而设计的。如果采用４４．１ｋＨｚ的取样频率,ＭＰ３的压缩比例能够达到１：１０～１：１２,而基本上拥有近似ＣＤ的音质。１分钟无压缩的ＣＤ音乐转换成文件需要１０ＭＢ的存储空间,如果压缩成ＭＰ３文件只需要１ＭＢ就够…     

VC＋＋下MP3文件播放的实现

ＭＰ３是 ＭＰＥＧ－１标准的音频 Ｌａｒｅｒ Ⅲ（第 ３层）。 ＭＰＥＧ（Ｍｏｖｉｎｇ Ｐｉｃｔｕｒｅ Ｅｘｐｅｒｔｓ Ｇｒｏｕｐ）标准是由国际标准化组织（ＩＳＯ）和国际电工委员会（ＩＥＣ）共同制订的,用于数字存储媒体的运动图像和伴音的编码。ＭＰＥＧ－１的音频标准分为３层, Ｌａｓｅｒ Ⅲ编码最为复杂,压缩率也最高,压缩比为 １：１０～１：１２时,接近ＣＤ音质,而其存储空间大大减少,便于在网络上传输,因而在网络中迅速崛起。 ＭＰ３的编码非常复杂,在ＶＣ＋十下如果通过自己编写解码程序来实现ＭＰ３文件的播放,不…     

无内部冲突满足P3的无α环的数据库模式分解（Ⅱ）：分解的算法及分析

文中在文献［１］、［２］、［３］、［４］讨论的基础上给出了数据库模式无内部冲突时，满足Ｐ３且为无α环的分解算法、正确性证明和分析．     

单滞后区间动力系统的稳定性

本文研究如下单滞后时变区间动力系统ｘ（ｔ）＝Ｎ［Ｐ，Ｑ］ｘ（ｔ）＋Ｎ［Ｃ（ｔ），Ｄ（ｔ）］ｘ（ｔ－τ），τ≥０的渐近稳定性的ａ稳定性，给出了其渐近稳定和ａ稳定的充分条件，推广和改进了文［１，２］的工作。     

The strong consistency of the stochastic gradient algorithm of adaptive control

By use of the technique of Chen [5] sufficient conditions are established for the strong consistency of the stochastic gradient (SG) algorithm for MIMO ARMAX stochastic systems without monitoring. This result is then used in conjunction with the method of disturbed adaptive controls introduced in [1], [2]. Hence it is shown that the SG algorithm generates strongly consistent parameter estimates while it is operating as a part of the SG algorithm of adaptive control of Goodwin, Ramadge, and Caines [6].     

一个军网身份鉴别协议的形式化分析及修正

分别使用形式化分析工具Casper+FDR和OFM C模型检测器对文[1]提出的一个军网身份鉴别协议进行了分析,找到了一个相同的攻击实例。同时指出了文[1]和文[2]中存在的几个谬误。然后对协议进行了修正。形式化验证结果表明修正后的协议是安全的。     

Language-measure-theoretic optimal control of probabilistic finite-state systems

Supervisory control theory for discrete event systems, introduced by Ramadge and Wonham, is based on a non-probabilistic formal language framework. However, models for physical processes inherently involve modelling errors and noise-corrupted observations, implying that any practical finite-state approximation would require consideration of event occurrence probabilities. Building on the concept of signed real measure of regular languages, this paper formulates a comprehensive theory for optimal control of finite-state probabilistic processes. It is shown that the resulting discrete-event supervisor is optimal in the sense of elementwise maximizing the renormalized langauge measure vector for the controlled plant behaviour and is efficiently computable. The theoretical results are validated through several examples including the simulation of an engineering problem.     

Discrete events and general systems theory

A new formal approach to the qualitative modelling of general time systems is introduced. The formalism is suitable for general non-deterministic systems with non-numerically valued inputs and outputs, e.g. for discrete event systems. The following basic concepts of systems theory, observability, causality, determinism and interconnections of systems, are defined using an input-output approach to the modelling. The concept of the state is introduced as a secondary one. A general definition of the discrete event systems is given. Some fundamental properties of systems are proved. A real-time extension of the supervisory control problem given by Ramadge and Wonham is formulated. Seven examples are provided.     

Control of vector discrete-event systems. I. The base model

A vector discrete-event system (VDES) is a discrete-event system model in which the system state is represented by a vector with integer components, and state transitions by integer vector addition. The authors investigate such structures from the viewpoint of control theory. The objective is to specialize to VDES the general automation-based control theory of P.J. Ramadge and W.M. Wonham (1987) and W.M. Wonham and P.J. Ramadge (1988). It is shown that within the VDES framework a useful class of control systems can be compactly modeled, and some of the associated control problems of Ramadge and Wonham can be more efficiently solved     

Input/output discrete event processes and communication delays

This paper proposes an input/output interpretation for the control of discrete event systems. In supervisory control theory, the plant is usually considered to be a process which spontaneously generates outputs. Its behavior is controlled by disabling some of its output events. In this paper the plant accepts inputs (commands) and generates outputs (responses). For many real-life problems, e.g., manufacturing problems, this model semantics seems more applicable than the original generator perspective proposed by Ramadge and Wonham. In real-life systems the message exchange between the plant and the controller is affected by communication delays. The class of supervisors that must be used in a closed-loop system subject to communciation delays is a subset of the set of solutions to the original problem introduced by Ramadge and Wonham. After having characterized this class of supervisors, the present paper states conditions on the plant language that allow the supervisors solving the (delay-free) supervisory control problem of Ramadge and Wonham to be used also for the case of closedloop systems affected by delays.     

Discrete Event Systems for autonomous mobile agents

Discrete Event Systems (DES) are a special type of dynamic system. The ‘state’ of these systems changes at discrete instants in time and the term ‘event’ represents the occurrence of discontinuous change (at possibly unknown intervals). Different Discrete Event Systems models are currently used for specification, verification, synthesis as well as for analysis and evaluation of different qualitative and quantitative properties of existing physical systems. The focus of this paper is the presentation of the automata and formal language model for DES introduced by Ramadge and Wonham and its application to the domain of mobile manipulator/observer agents. We demonstrate the feasibility of the DES framework for modeling, analysis and synthesis of some visually guided behaviors of agents engaged in navigational tasks and address synchronization issues between different components of the system. The use of DES formalism allows us to synthesize complex behaviors in a systematic fashion and guarantee their controllability.     

On controllability of discrete event systems in a behavioral framework

The purpose of this paper is to investigate the controllability and the achievability of discrete event systems within a behavioral framework. Based on the notion of Willems’ behavioral controllability [1, 2], we introduce a new concept related to the controllability of discrete event systems. By using the controllability proposed here and the notion related to achievable behaviors [3, 4], we show that the behavioral controllability for a given specification with respect to language is equivalent to the existence of a controller, so that an interconnected system satisfies the specification exactly. A proposed controller here is represented by the intersection of the behavior of a given plant and that of a given (controllable) specification. We also clarify that our controllers for a given specification fit the properties of well-known supervisory controllers proposed and developed by Ramadge and Wonham [5]. The text was submitted by the authors in English.     

谓词形式系统(A)UL-h∈[0.75,1]及其可靠性

对基于一级泛与运算的一阶谓词演算形式系统(A)UL-h∈[0.75,1]进行公理化.通过引入全称量词和存在量词,建立与命题形式系统(A)UL-h∈[0.75,1]相对应的一阶谓词形式系统V(A)UL-h∈[0.75,1]并证明该系统的可靠性定理及演绎定理.     

On transformations of formal power series

Formal power series are an extension of formal languages. Recognizable formal power series can be captured by the so-called weighted finite automata, generalizing finite state machines. In this paper, motivated by codings of formal languages, we introduce and investigate two types of transformations for formal power series. We characterize when these transformations preserve recognizability, generalizing the recent results of Zhang [16] to the formal power series setting. We show, for example, that the “square-root” operation, while preserving regularity for formal languages, preserves recognizability for formal power series when the underlying semiring is commutative or locally finite, but not in general.