An optimal effective controller for discrete event systems

An approach to the online synthesis of an optimal effective controller for discrete event systems is presented. The optimal effective controller can achieve the prescribed (cumulative) effectiveness measure while minimizing the total cost incurred for the execution of events. This approach is constructed over a generalized control framework for automata‐based discrete event systems, which allows event enforcement in addition to the (original) event disablement/enablement as the control mechanism. The optimal effective control policy generated by this approach is proved to be the least restrictive among all the possible optimal effective control policies for the given online expansion tree of the system behavior. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Optimal Control of Two-Stage Discrete Event Systems with Real-Time Constraints

We consider discrete event systems (DES) involving tasks with real-time constraints and seek to control processing times so as to minimize a cost function subject to each task meeting its own constraint. When tasks are processed over a single stage, it has been shown that there are structural properties of the optimal sample path that lead to very efficient solutions of such problems. When tasks are processed over multiple stages and are subject to end-to-end real-time constraints, these properties no longer hold and no obvious extensions are known. We consider a two-stage problem with homogeneous cost functions over all tasks at each stage and derive several new optimality properties. These properties lead to the idea of introducing “virtual” deadlines at the first stage, thus partially decoupling the stages so that the known efficient solutions for single-stage problems can be used. We prove that the solution obtained by an iterative virtual deadline algorithm (VDA) converges to the global optimal solution of the two-stage problem and illustrate the efficiency of the VDA through numerical examples.

A framework for a video analysis tool for suspicious event detection

This paper proposes a framework to aid video analysts in detecting suspicious activity within the tremendous amounts of video data that exists in today’s world of omnipresent surveillance video. Ideas and techniques for closing the semantic gap between low-level machine readable features of video data and high-level events seen by a human observer are discussed. An evaluation of the event classification and detection technique is presented and a future experiment to refine this technique is proposed. These experiments are used as a lead to a discussion on the most optimal machine learning algorithm to learn the event representation scheme proposed in this paper.

扩展时间事件图的能达性与能控序列

利用图论方法在双子结构中研究扩展时间事件图的某些问题,获得了能达性的一个充分必要条件和基于能达性的标准结构。在此基础上,把监控理论中的能控序列的分量分为本质不同的３类,进而得到能控序列的简化求解方法。     

认真深入做好前期工作确保三峡工程顺利兴建

三峡工程建设,无论是防洪,发电、航运其工程规模极其巨大,而且工程建设地处我国人口密集、经济相对较发达的长江干流上游最下部河段上;为此,工程建设的前期工作更应较全面深入周密细致,充分考虑方方面面的利害得失,正确地反映工程建设的经济效益。在开发性移民方针下,做好水库淹没损失的合理补偿和移民安置,不留后患。长江上游年年发生洪水造成灾害,工程设计应考虑在水库调洪运行中给上游带来的洪涝灾害淹没损失应得到相应的赔偿。执行《水法)对水资源的有偿使用经济收益的分配是一个有待探讨的问题。     

A MODIFIED METHOD FOR SUPERVISOR SPECIFICATION AND SYNTHESIS OF A CLASS OF DISCRETE EVENT SYSTEMS

In this paper, a model‐refining method is proposed to alleviate the complexity involved in specification interpretation of DES control problems. The legal constraint language is defined in terms of illegal states and events in contrast with constructing the automaton of the specification language. This method could provide a more intuitive view of the DES control problem and would be suitable for practical implementation. Two examples, which have commonly been used in the literature, are employed to show the efficiency of the proposed method. Further, under this framework, it is shown that the supremal controllable sublanguage can take a simpler form based on the concept of an illegal state set. A state‐based supervisor synthesis procedure is presented, and a simple example is provided.     

用C＋＋Builder编写基于线程的串行通信程序

本文介绍了Ｗｉｎ９５下线程多任务的基本原理和串行通信中使用的主要ＡＰＩ函数,并使用线程的方法在Ｃ＋＋Ｂｕｉｌｄｅｒ下开发实时性要求很高的Ｗｉｎ９５下的串行通信程序。     

Response-time simulation of multivariate point process models for multiprogrammed jobstreams

We consider simulation methods for particular marked multivariate point processes, calledR-processes, which have recently been proposed as models for multiprogrammed jobstreams. Using workload marks on events, such models facilitate the incorporation of realistic workload characteristics into computer system performance predictions. We consider R-processes in which workload marks for an individual jobstream form a stationary sequence of discrete random variables having a (generally non-Markovian) mixed moving average-autoregressive dependency structure. For such models we provide a method for obtaining from a single simulation run point and interval estimates for general characteristics of job response times.     

中国大坝设计洪水计算、评估与确定

回顾了新中国成立60年来中国大坝设计洪水计算的发展历程,总结了取得的经验和教训。在介绍现行规范规定的大坝设计洪水计算方法基础上,重点对中国大坝设计洪水的评估与确定进行了分析研究。