一种基于Petri网的分布组件协调模型

协调是分布组件系统中的基本问题之一.但是,协调问题至今仍未得到很好的解决.根据实际应用的要求,提出了Concerto协调模型.它以Petri网为数学理论基础,扩充了Petri网的语义,引入了控制缓存和数据缓存,分别反映了分布组件的控制依赖和数据依赖关系,统一了现有的控制驱动和数据驱动两类协调模型.对于Concerto模型的运行,提出了驱动模式、动作规则和Concerto引擎.驱动模式有4种:依赖操作时间的驱动、依赖最小时间的驱动、依赖最大时间的驱动和依赖平均时间的驱动.这些驱动模式在实时系统、流量控制和任     

一种面向分布组件的协调引擎实现框架

针对现有的Concerto协调模型,提出了一种面向分布组件的协调引擎实现框架,它将模型中的协调问题转化为独立的计算性代码,以便于系统在设计阶段就可以分析并解决协调问题。由于引擎本身具有分布特性,因此针对一些现有的协调问题,运行在引擎上的协调模型可以相当接近现实中出现的问题。     

基于组件的机械系统虚拟样机可视化建模研究

应用组件技术,将机械系统虚拟样机分析系统设计为独立于几何模型的组件,这样简化了系统分析的复杂性,提高了可扩展性和可移植性。采用基于组件技术的三维引擎ACIS,重用其基本功能组件,实现了机械系统虚拟样机的几何构件体,约束和载荷的可视化建模。     

虚拟企业生产协调的实现研究

由于虚拟企业的分布式特点,其内生产的相互协调尤其重要。为此提出用互操作Ｐｅｔｒｉ网（ＩＰＮ）的同步协调机制来实现虚拟企业的功能。     

基于OpenGL可视化组件的设计与实现

介绍了使用OpenGL作为基本开发工具,结合组件技术,设计并实现了一套具有丰富表现形式的可视化组件的设计思想、方法和结构,以及应用该组件完成的实例。该组件的设计充分应用了面向对象和组件技术,具有支持3D旋转、平移、缩放和漫游以及允许进行光照、雾化、透明等特效处理。     

网络安全组件组合强度研究

介绍了安全组件组合安全强度分析的现实意义,对现有方法进行研究,重点探讨了安全边界已知情况下安全组件组合的安全特性。研究段云所副教授所提出的理论,并以其方法为基础,提出了一种基于Petri网的网络系统安全组件组合强度分析方法,进一步研究了Petri网模型的构造,并利用Petri网仿真工具ExSpect对所提出方法的正确性进行仿真验证。     

分布多媒体系统的多媒体动态同步模型

在分布多媒体系统中，多媒体具有动态同步特性，同时关键媒体的同步要求在应用中享有优先权．现有的多媒体同步模型无法满足这些要求，现提出一个新的基于时间Ｐｅｔｒｉ网的多媒体动态同步模型——ＤＳＰＮ模型．它不仅能使分布多媒体系统依据实际运行状况和新提出的同步类型，以更准确、高效的方式来保持多媒体同步，而且允许用户对多媒体表现过程进行交互操作．     

异构环境下分布组件的对象互操作性的研究

分析了三种目前主要的分布组件模型的特点、体系结构和通信模型。重点讨论了COM／DCOM,CORBA和RMI／EJB三种组件之间的互操作能力,最后给出了一个异构环境下的分布式组件的交互模型。     

一种Petri网层次模型建模工具的设计与实现

为解决使用Petri网建模遇到的状态空间爆炸问题,提出使用层次模型,采用分层细化逐步求精的方法建立Petri网分层模型.设计并实现基于图形用户界面的普通边界为1的Petri网分层建模工具软件.用户在交互方式下建立Petri网层次模型,并可修改、删除、存储、分层平面化、简单功能模拟、导入和导出可复用Petri子网和将模型翻译为预定义的模型描述语言源程序.     

离散事件系统的协调反馈控制

本文探讨以Ｐｅｔｒｉ网为模型的离散事件系统（ＤＥＳ）的某种禁止状态避免问题,提出了以Ｐｅｔｒｉ网Ｎ为基网,设计具有外部输入位置Ｐｅｔｒｉ网（ＰＮＩＰ）,对Ｎ进行协调反馈控制的方法。由Ｎ现行状态反馈决定的ＰＮＩＰ的控制状态,既保证Ｎ避免禁止状态,又使Ｎ具有最大自由度。     

Modeling the Exogenous Coordination of Mobile Channel-based Systems with Petri Nets

In this paper, we discuss how to model systems that communicate through and are coordinated by mobile channels. Mainly, we focus on modeling the exogenous coordination behavior imposed by these channels. We use Petri Nets as our modeling language, for they provide a graphically and mathematically founded modeling formalism. We give Petri Nets for a set of mobile channel types. This allows us to construct models of applications, by taking the Petri Net of each component and each mobile channel, and composing them together. For this purpose, we define a special Petri Net composition function. We also discuss analysis and simulation of these models and their exogenous coordination behavior.     

Dynamical Quantities in Net Systems

The paper presents some known material of higher-level Petri nets in analogy to the dynamics of physical systems. Its aim is to widen the view on the role of the incidence matrix in the analysis of net systems. Rather than focusing on constant state quantities (S-invariants) and cyclic actions (T-invariants), i.e. on solutions of the homogeneous equation systems based on the incidence matrix, it studies dynamical quantities of net systems in general. Received March 2000 / Accepted in revised form March 2002 RID="¹" ID="¹" This work was done while the author was with GMD { National Research Center for Information Technology (now Fraunhofer Gesellschaft). Part of it was funded by Deutsche Forschungsgemeinschaft, Priority Programme Analysis and Synthesis of Continuous–Discrete Engineering Systems (KONDISK), Ref. No. GE 933/1-2. Correspondence and offprint requests to: Hartmann J. Genrich, Peter-Ohlenhardt-Str. 5, D-53127 Bonn, Germany. Email: hartmann.genrich@gmd.deau     

基于随机对象Petri网的柔性制造系统性能分析

为了增强传统对象Petri网的定量分析能力,提出随机对象Petri网模型。该模型具备随机性和层次特性,获得与随机Petri网的等价关系,从宏观和微观2个层面对系统进行性能分析,并将该模型应用到柔性制造系统中。实验结果表明,该系统保留了面向对象的建模能力,具有较强的定量分析能力。     

时延Petri网分布式模拟的先行值研究

先行值计算是提高时延Petri网并行模拟性能的一个好的方法。给出了时延Petri网的先行值计算的四种基本结构,对于存在循环的复杂的Petri网结构给出了预测图算法,通过预测图,能够很容易求出静态和动态先行值,在并行模拟中利用先行值可以分析出存在并发和阻塞的结构,从而为网分块在并行机的结点上运行奠定了基础。     

DISTRIBUTED SIMULATION OF HIGH-LEVEL ALGEBRAIC PETRI NETS WITH LIMITED CAPACITY PLACES

The aim of this paper is to search for techniques to accelerate simulations exploiting the parallelism available in current multicomputers, and to use these techniques to study a class of Petri nets called high-level algebraic nets. These nets exploit the rich theory of algebraic specifications for high-level Petri nets. They also gain a great deal of modelling power by representing dynamically changing items as structured tokens whereas algebraic specifications turned out to be an adequate and flexible instrument for handling structured items. We focus on ECATNets (Extended Concurrent Algebraic Term Nets), a kind of high-level algebraic Petri nets with limited capacity places

Three distributed simulation techniques have been considered: asynchronous conservative, asynchronous optimistic and synchronous. These algorithms have been implemented in a network of workstations with MPI (Message Passing Interface). The influence that factors such as the characteristics of the simulated models, the organisation of the simulators and the characteristics of the target multicomputer have in the performance of the simulations have been measured and characterized

It is concluded that distributed simulation of ECATNets on a multicomputer system can in fact gain speedup over the sequential simulation, and this can be achieved even for small scale simulation models.     

调度问题的HPN模型研究

本文介绍了层次Ｐｅｔｒｉ网模型（ＨＰＮ）的概念。层次Ｐｅｔｒｉ网的特点在于它不仅可以在某一层次上模拟系统的局部行为，而且还可以通过一定的关联机制来表现系统的整体特性。本文还通过研究调度问题的ＨＰＮ模型，探讨了如何应用ＨＰＮ来分析调度问题，为进一步研究调试方法提供了基础。     

Tutorial and Survey Articles: An introduction to Petri Nets

This paper describes the fundamental concepts and characteristics of Petri nets (PNs) that make them a significant tool for modeling and analyzing asynchronous systems with concurrent and parallel activities and follows the extensions that improved the implementation capabilities of the original PNs.

Their first and most relevant extension was time modeling, a vital aspect of system performances not considered in the original version. There are several possibilities for introducing time in PNs. Among them, a technique that associates time with places is presented in some detail. As PNs tend to become cumbersome and time consuming when large and complex systems are involved, a method for decomposing timed PNs of open queuing networks is reviewed here.

Though initially developed as an information/computer-based technique, PNs were immediately adopted in a variety of application areas, such as manufacturing, design, planning and control. Viewed through a more recently developed programming perspective, the ordinary PNs became “high level” PNs suitable for defining different data types and for applying hierarchical approaches.

It is expected that the robust theoretical basis of this tool coupled with its visual and flexibility features will continue to appeal to researchers and practitioners alike in a variety of domains and as a result will continue to evolve and expand.     

TCPN的状态可达及可调度决策空间算法

Ｔｓａｉ等提出了时间限制Ｐｅｔｒｉ，并讨论了变迁可激活，可调度规律及其计算公式。然而，由于网拓扑和动态的复杂性，某些概念的逻辑关系及公式有矛盾。本文通过引入调度决策变量，动态标记准确地刻画调度规律，修正澄清了Ｔｓａｉ文中的问题，完善了ＴＣＰＮ的调度分析。另外，讨论了ＴＣＰＮ沿含有失败变迁激活路径的调度问题。