生产系统业务和制造流程再造的层次化方法

运用约束理论的思想,结合Petri网建模工具,提出了一种生产系统再造的流程结构优化和瓶颈优化的层次化方法,并对如何运用时间Petri网模型寻找和消除约束进行了探讨.这一方法有助于有效确定再造的重点,明确再造范围,从而提高再造的成功率.最后介绍了这个方法在企业的应用.     

业务流程再造建模技术研究

建模技术是业务流程再造的关键技术之一，对业务流程的增值性能的描述和分析支持不足是应用于业务流程再造的建模技术的一个重要缺陷。本文在比较分析现有建模技术的基础上，提出了基于Petri网的面向对象建模技术，并利用该技术所建立的模型地流程活动建模的实现和流程再造的分析评价体系进行了探讨。     

协同环境下产品开发过程建模的研究

对现代产品开发过程的特点进行了探讨,分析了国内外协同设计过程建模的研究现状。在此基础上,以全局导航、局部决策的思想,提出基于UML活动图和Petri网的分层建模方法。通过用UML活动图对产品开发全局过程进行描述,确定了过程视图和其他派生图之间的关系,提出了视图间的组织结构方法。同时通过对具体生产环节的Petri网描述,达到使管理人员对局部进行有效控制的目的。     

医疗信息系统工作流的Petri网建模与化简分析

应用 Petri网建模与工作流技术,构建了基于医疗信息整合(IHE)规范的医疗信息系统工作流的Petri网模型,并对一个医疗信息系统工作流实例,给出了基于Petri网化简分析方法的模型化简与性质验证,表明该模型能够对医疗信息工作流进行有效的分析和验证,从而为医疗信息系统集成设计及其工作流分析提供了理论基础.     

信任协商策略的Petri网建模分析方法

对Peer-to-Peer网络环境下信任协商和信任协商策略进行了定义和形式化描述,提出了一种基于Petri网模型的信任协商策略建模分析方法,将资源、证书和资源访问策略映射为Petri网网元进行建模,通过可达分析寻找最优资源解锁序列.和其他信任协商策略建模方法相比,该方法具有较好的性能.     

对业务流程重组在月生产计划中的应用问题的研究

重点对企业生产计划进行深入研究.在业务流程重组思想的指导下,讨论企业工艺流程的重组.适应中小型企业根据企业内外的各种资源约束来编制月生产计划并指导企业的生产加工,以实现最大的经济效益.     

基于六西格玛项目选择原理的BPR核心流程确定方法

在分析企业核心竞争力与业务流程再造关系的基础上,提出了基于核心竞争力的业务流程再造模式.在这个模式中运用六西格玛项目选择原理,建立了核心竞争力的分散要素与业务流程环节之间的相关矩阵,对影响核心竞争力的业务流程环节进行综合评价,并进行优先排序,然后企业根据实际条件选择出要再造的核心流程.以实际企业为案例验证了此方法.     

基于模糊Petri网考虑制造约束的零件表面加工方案决策方法

加工方案决策是计算机辅助工艺规划中一直未能完全解决的关键问题.首先,在给出Petri网系统和T-不变量定义的基础上,根据Petri网原理和产生式规则建立一个基于模糊规则的零件表面加工方案Petri网模型;然后,根据Petri网T-不变量在考虑制造资源约束的条件下,提出一种新的可选加工方案T-不变量生成方法;最后,通过实例验证了所提方法的有效性.实例结果表明,采用作者提出的决策方法能够获得零件表面加工的最优/次优工艺方案.     

业务流程时间性能定量分析

时间性能的定量分析是保证流程模型有效性和提高业务流程质量的关键.针对管理型流程的特点,基于任务活动执行时间为零或者服从指数分布的假设,建立了业务流程的广义随机工作流网模型,并利用广义随机Petri网和马尔可夫链理论来分析流程的时间性能,获得了流程平均执行时间的计算公式,最后给出了应用验证实例并和仿真结果进行了比较.     

基于模糊Petri网考虑制造约束的零件

加工方案决策是计算机辅助工艺规划中一直未能完全解决的关键问题.首先,在给出Petri网系统和T_不变量定义的基础上,根据Petri网原理和产生式规则建立一个基于模糊规则的零件表面加工方案Petri网模型;然后,根据Petri网T_不变量在考虑制造资源约束的条件下,提出一种新的可选加工方案T_不变量生成方法;最后,通过实例验证了所提方法的有效性.实例结果表明,采用作者提出的决策方法能够获得零件表面加工的最优/次优工艺方案     

Assembly/disassembly task planning and simulation using expert Petri nets

Automatic assembly/disassembly planning is recognized as an important tool for reducing the manufacturing costs in concurrent product and process development. This paper developed a knowledge-based expert Petri net model by incorporating expert system techniques in artificial intelligence into ordinary Petri nets for an analytical framework of understanding, representing and reasoning the assembly/disassembly tasks. Substantial extensions have been made to ordinary Petri nets by adding control places, time constraints, and place and transition knowledge annotations. The proposed expert Petri net model can be considered as the hybrid of expert systems and ordinary Petri nets. Through these extensions, the capacities of modelling and representation of ordinary Petri net models are largely enhanced, and thus the expert Petri net models are more powerful than ordinary Petri nets. Such intelligent Petri net models can combine the abilities of modelling, planning, and performance evaluation for assembly/disassembly tasks in an integrated and intuitive way, and can therefore be applied to either linear/non-linear, static/dynamic, or on-line/off-line assembly/disassembly tasks at both high and low levels. The developed assembly/disassembly planning system can generate the best strategies and plans for assembly/disassembly. The research findings are exemplified with a real assembly to show the effectiveness of the method.     

Expert Enhanced Coloured Stochastic Petri Net and its application in assembly/disassembly

This article comprises of an Expert Enhanced Coloured Stochastic Petri Net (rule base system, or RBS) for modelling and analysing assembly/disassembly systems. RBSs are an Enhanced High-level Petri net extended with Close-World-Assumption (CWA). Traditional Petri nets can be used to model RBSs containing explicitly described knowledge. The main focus was is to facilitate and analyse the process planning activities of assembly/disassembly. The advantages of the new modelling approach were: (1) consideration of the non-desirable events, (2) occurrence of assembly/disassembly tasks with regard to colour of the tokens and utilization of probability concept to determine feasible steps, (3) establishing a relationship among components by means of arc labels, and (4) deeper insight into the assembly/disassembly process using high- and low-level petri nets.     

Decomposition in automatic generation of Petri nets for manufacturing system control and scheduling

Despite the efforts in developing Petri net models for manufacturing control and scheduling, the generation of Petri net models cannot be automated for agile manufacturing control and scheduling without difficulties. The problems lie in the complexity of Petri net models. First of all, it is difficult to visualize the basic manufacturing process flow in a complex Petri net model even for a Petri net modelling expert. The second problem is related to the complexity of using Petri net models for manufacturing system scheduling. In this paper, a decomposition methodology in automatic generation of Petri nets for manufacturing system control and scheduling is developed. The decomposition methodology includes representing a manufacturing process with the Integrated Definition 3 (IDEF3) methodology, decomposing the manufacturing process based on the similarity of resources, transforming the IDEF3 model into a Petri net control model, and aggregating sub Petri net models. Specifically, a sequential cluster identification algorithm is developed to decompose a manufacturing system represented as an IDEF3 model. The methodology is illustrated with a flexible disassembly cell example. The computational experience shows that the methodology developed in this paper reduces the computational time complexity of the scheduling problem without significantly affecting the solution quality obtained by a simulated annealing scheduling algorithm. The advantages of the methodology developed in this paper include the combined benefits of simplicity of the IDEF3 representation of manufacturing processes and analytical and control properties of Petri net models. The IDEF3 representation of a manufacturing process enhances the manmachine interface.     

Implementation of Petri nets using a field‐programmable gate array

Although Petri nets have various capabilities, the Petri net approach is done on paper. A field‐programmable gate array (FPGA) is implemented in this study so as to realize basic Petri net symbols, logic structures in Petri nets, and specific functions for Petri nets by logic circuits. As an example, a Petri net for an early failure detection and isolation arrangement (EFDIA) is implemented as an application‐specific integrated circuit (ASIC) on a Xilinx Demonstration Board. This ASIC is verified by three simulations dealing with three different failure scenarios of a system, and the ASIC functions identically to the EFDIA Petri net. Accordingly, not only the EFDIA Petri net but also any specific function Petri nets can be implemented by FPGA circuits. Copyright © 2000 John Wiley & Sons, Ltd.     

基于eM-Plant求解具有晶圆重入过程的单臂组合设备最优调度的仿真方法

在半导体组合设备的晶圆加工过程中,常常要求晶圆重入,原子层沉积加工(ALD)就是典型的晶圆加工过程。对这样的系统实施调度是一个挑战性的问题。研究单臂组合设备的调度问题,目的在于求解ALD重入过程的最优调度。建立了系统的Petri网模型,利用该模型,可以通过比较非常有限的若干调度的生产节拍而得到其重入过程的最优调度。基于所建立的Petri网模型,开发出了基于eM-Plant的仿真系统,可以有效地获得给定调度的生产节拍。给定系统的参数可以有效地求得重入过程的最优调度。文中应用例子来说明所提出的方法的应用。     

Modelling and planning of the disassembly processes using an enhanced expert Petri net

A sound disassembly Petri net model for the effective planning of disassembly processes and tasks is outlined. Owing to the unmanageable complexity associated with modelling of the disassembly processes and tasks, it becomes essential to have a more powerful Petri net model developed by incorporating the concepts of expert system, knowledge representation techniques, etc. Disassembly task planning at high and low levels can easily be represented by proposed high- and low-level expert Petri net. An algorithmic approach is also suggested for evaluating the end-of-life values of a product. These values are used to determine an optimal disassembly sequence and it is incorporated in the expert disassembly Petri net. A proposed expert enhanced high-level coloured disassembly Petri net is empowered to express such details vividly. The application of the proposed expert enhanced high-level coloured disassembly Petri net model is demonstrated through the sample disassembly of a flashlight.     

Supply chain configuration with co-ordinated product,process and logistics decisions: an approach based on Petri nets

Supply chain configuration lends itself to be an effective means to deal with product differentiation and customisation throughout a supply chain network. It essentially entails the instantiation of a generic supply chain network to specific supply chains in accordance with diverse customer requirements. The lynchpin of supply chain configuration lies in the co-ordination of product, process and logistics decisions in relation to a variety of customer orders. This paper aims to provide modelling support to supply chain configuration. The ultimate goal is to assist companies to form appropriate supply chains with the most added-value to customer order fulfillment. A formalism based on coloured Petri nets is developed for configuring supply chains. System models are built upon the coloured Petri nets and used to incorporate product and process concerns into the supply chain configuration process. An industrial case study is reported to illustrate the potential of the coloured Petri net modelling formalism and the built system models for supply chain configuration.     

混杂Petri网在企业能源系统建模中的应用

能源模型是一种能源系统工程的研究方法,企业级能源模型是研究企业级能源系统的重要手段,也是企业系统节能的基础。总结国内外各种能源模型,并在对钢铁企业生产流程分析研究的基础上,抽象出主要能源流程,利用混杂Petri网(HPN)对整个钢企的能源系统建立能源模型,给出基于Stateflow的能源系统HPN模型的仿真步骤,并给出实例,为进一步分析和优化能源系统提供了支持。     

Petri net based scheduling

Timed Petri nets can be used to model and analyse scheduling problems. To support the modelling of scheduling problems, we provide a method to map tasks, resources and constraints onto a timed Petri net. By mapping scheduling problems onto Petri nets, we are able to use standard Petri net theory. In this paper we will show that we can use Petri net based tools and techniques to find conflicting and redundant precedences, upper- and lower-bounds for the makespan, etc. This is illustrated by a Petri net based analysis of the notorious 10×10 problem due to Fisher & Thompson (1963)     

Development of a decision-support system for the formulation of manufacturing strategy

Corporate strategy can be divided into various substrategies, such as marketing, manufacturing, research and development, etc. In the current enterprise environment, products are highly varied and product life-cycles are shortening owing to customers' changing needs and market competition. In such an environment, the formulation of a good manufacturing strategy is critical for the success of manufacturing enterprises. In this research, for the establishment of good manufacturing strategy, we propose a framework enabling a decision-support system for the modelling and analysis of the manufacturing system. For this task, we have constructed a single integrated object model that contains information about products, processes and resources in the manufacturing system. The model is flexible, allowing the objects in the model to be defined according to the levels of detail required by analysis. The process model can then be transformed to a generalized stochastic Petri net (GSPN). Furthermore, a Petri net separation procedure is presented to relieve the complexity of the analytic method. By using the analytic analysis of GSPN, the system throughput is easily obtainable. An example is included to demonstrate the applicability of this framework. The proposed decision-support system for manufacturing strategy formulation enables (1) the analysis of the relationship between strategic input variables and performance measures, (2) the scenario evaluation for coordination between the manufacturing department and other departments, and (3) the formulation of manufacturing strategy using what-if analysis against dynamic manufacturing environments.