Petri nets

Petri nets offer a versatile modeling framework for complex, distributed, concurrent systems and have been used in a wide range of modeling applications. The first part of this two-part article provides an overview of Petri nets and presents important conceptual underpinnings of Petri net modeling.     

基于扩展Petri网的混合系统建模方法

为了对混合系统进行有效地建模,提出了一种扩展的面向对象混合Petri网(EOHPN)建模方法.针对混合系统的复杂性,在EOHPN模型中融入了面向对象的抽象机制,例如封装和类定义.为了结合混合系统的连续部分和离散部分,减少混合系统的复杂性,引入混合Petri网并用面向对象建模技术作了扩展.在定义EOHPN模型的基础上,拓展了对象模型.最后,用实例描述了基于EOHPN的混合系统建模过程,同时验证了EOHPN模型在处理复杂混合系统建模时是有效的.     

Development of a plastic injection molding training system using Petri nets and virtual reality

INTRODUCTIONAt present, plastic as a substitute for metals in products is the most important mainstay in industrial raw materials. Furthermore, plastic injection molding is one of the most common and versatile methods for mass production of complex plastic parts with excel-lent dimensional tolerance. Since the technology of injection molding has been widely applied in manu-facturing, training on injection molding is of great importance. The traditional approach is to consult some technica…     

Generalized stochastic Petri nets based models for performance analysis of communication networks of IEC61850 system

1 Introduction a After many years’ research and developments, communication networks have demonstrated more and more important functions in a substation automation system (SAS). In our experience in developing and applying such systems, we have witnessed…     

Stochastic individual predicate/transition nets

We analyze the drawbacks of generally distributed time transition stochastic Petri nets （GDTT_SPN） in evaluating the performance of parallel systems, and propose a more general model, stochastic individual predicate/transition nets （SIPTN）. SIPTN has higher modeling power and could provide more realistic models compared to GDTT_SPN, because in SIPTN the sojourn time distribution is determined not only by the transition, but also by the individuals. It is further proved that GDTT_SPN is a subset of SIPTN. As SIPTN introduces folding techniques from predicate/transition nets, SIPTN models have simpler and more intuitive graphic notations and accordingly higher usability, and thus are suitable for constructing simulation models for parallel systems.     

局域网的优化分析

随着计算机技术的发展,局域网的作用越来越大。网络的速度、稳定性等问题是局域网的关键。从布线、服务器、交换机、工作站、协议等几个方面来优化局域网,使得局域网具有更快的速度、更强的稳定性。     

基于petri网的自动信任协商理论研究

在以往的自动信任协商研究中,Petri网很少被用于构造策略模型。提出一种基于petri网的自动信任协商进行合理建模和分析,提供了形式化建模方法和验证,并通过VC程序对其进行了模拟验证,达到了对自动信任协商理论研究的目的。     

校园网建设初探

随着现代化教学活动的开展和与国内外教学机构交往的增多．对通过Internet／Interanet网络进行信息交流的需求越来越迫切。为促进教学、方便管理和进一步发挥学生的创造力，校园网建设成为学校发展的重要基础设施．本文着重探讨校园网建设中应该考虑的问题及解决发方案。     

Formative Autonomy: Lessons from Elio Petri

John Baldacchino's discussion of the concept of autonomy in this article runs on the dual track of the arts and education. His aim is to engage with the notion of autonomy in terms of what human beings invent (through art) and know (through education) by what they share as free and intelligent beings who live convivially. Following Luigi Pareyson's argument that by form one means a living organism endowed by its own legality (and thereby its own autonomy), Baldacchino offers an analysis of Elio Petri's film La classe operaia va in Paradiso (The Working Class Goes to Heaven) as context for this discussion, which adds a third dimension to the notion of autonomy: that of the political. Here, autonomy is presented as a triangulation of sorts, where what we mean by the autonomous stands for our artistic, educational, and political dispositions (and abilities) to mediate and represent a number of immediate questions with yet-to-be-found answers.     

关于Petri网的代数结构

Petri网的研究通常利用网的几何结构.这样的结构不利于用计算机实现Petri网的计算工作.提出Petri网的代数结构.文中给出Petri网的代数定义,以及有关的概念的代数定义.Petri网的代数结构为Petri网的研究提供一种新的方法.     

WWW下基于Petri Net的协同编辑模型

工作流管理是一个以业务处理自动化为目标的新兴研究领域。近几年来Internet的发展深刻地影响着工作流管理系统。本文旨在用PetriNet这种非常适合描述离散动态系统的工具建立一个基于WWW环境的期刊协同编辑系统模型 ,使编辑流程规范化 ,也为后期开发提供可靠的理论基础     

关于Petri网的代数结构

Petri网的研究通常利用网的几何结构.这样的结构不利于用计算机实现Petri网的计算工作.提出Petri网的代数结构.文中给出Petri网的代数定义,以及有关的概念的代数定义.Petri网的代数结构为Petri网的研究提供一种新的方法.     

A real-time adaptive control algorithm using neural nets with perturbation

This paper proposes an adaptive algorithm of neural nets with a special perturbation for a real time velocity control system of a VVVF (Variable Voltage Variable Frequency) hydraulic elevator. The weight vector of the neural network is adaptively adjusted by the LMS (Least Mean Square) with perturbation, so it is not necessary to know the nonlinear continuous function of the control system. The nonlinear velocity control system is considered as the controller output function in an adaptive controller model. The experimental results obtained from the VVVF hydraulic elevator showed that the neural nets controller using the perturbation algorithm proposed are much stabler and faster in dynamic response compared with the conventional PID (Proportion-Integration-Derivation) controller. Project (69775013) Supported by NSFC     

用Petri网描述进程的死锁

死锁是操作系统的一个重要概念,本文提出用库所/变迁网直观、动态地描述并发进程的死锁,本人将这一方法用于操作系统有关死锁内容的教学取得了非常好的效果.     

关于单纯Petri网的全进程

引入了单纯Petri网的概念,设∑=(S,T;F,M_0)是可逆有界Petri网,已证明可逆有界Petri网可由几个单纯Petri网连接得到.因此,为了讨论可逆有界Petri网的全进程就有必要研究单纯Petri网的结构和全进程,并证明单纯Petri网的结构由其可达标识链决定,为进一步认知单纯Petri网的全进程提供新思路.     

几种弱形式连续映射的网式刻画

在一般拓扑空间中,以远域为工具引入和研究网的S-收敛性、θ-收敛性、δ-收敛性等概念,并利用这些概念给出半连续映射、弱连续映射和几乎连续映射的一些等价条件.     

NOVELL网络环境下用户通信软件的实现

该文叙述了NOVELL网络环境下,工作站与工作站之间,用户与用户之间进行数据通信的基本思想,及利用NOS提供的用户编程接口IPX进行通信程序编制的主要原理,并给出了编程实例.旨在提出当NOVELL本身提供的系统功能不能满足用户要求的情况下,进行自行开发通信程序的可能性、实用性.     

基于 Petri 网的分布式协同办公智能模 型简

介绍了Petri网的基本理论,分析了基于网络服务的分布式协同办公应用的特征,在此基础上提出了基于Petri网的分布式协同办公的通用智能模型,该模型具有语义明确、易于修改,并且易于验证的优点,最后以文档审批工作流为例给出了具体的模型实现过程．