基于SPNAT的维修过程建模与仿真方法研究

Petri网是严格定义的数学对象,直观、形象,且可用于动态的行为分析。通过引进退化令牌对随机Petri网进行理论扩展,提出了一种基于退化令牌的随机Petri网（SPNAT）的维修过程建模与仿真方法。最后通过实例验证了该建模方法的有效性和优越性。     

An intelligent modeling and analysis method of manufacturing process using the first-order predicate logic

Manufacturing process refers to machining sequence from raw materials to final products. Process plan has important effects on manufacturing process. In general, process designer relies on his experience and knowledge to arrange the process plan. For a complex part, it takes long time and effort to determine process plan. In this paper, an intelligent modeling and analysis method using the first-order predicate logic is proposed to evaluate the manufacturing performance. First, the logic predicates used to represent the process plan are defined according to the machining methods, and the predicate variables are discussed in detail. Consequently, the process plan can be represented in the form of the first-order predicate logic. Second, a type of element model composed of four nodes and four links is put forward in order to construct the process model. All components in this element model are respectively explained, and the mapping relationship between element model and predicate logic is described in detail. According to engineering practices, logic inference rules are suggested and the inference process is illustrated. Hence, the manufacturing process model can be constructed. Third, the process simulation is carried out to evaluate the performance of manufacturing system by using measures such as efficiency, the machine utilization, etc. Finally, a case study is given to explain this intelligent modeling method using the first-order predicate logic.     

Process modeling and analysis of manufacturing supply chain networks using object-oriented Petri nets

This paper presents a systematic methodology for modeling and analysis of manufacturing supply chain business processes. The proposed approach first employs Computer Integrated Manufacturing Open System Architecture (CIMOSA) behavior rules to model the business process routing structures of manufacturing supply chain networks. Object-oriented predicate/transition nets (OPTNs) are then developed for the modular modeling and analysis of process models. Based on the structure of OPTNs, a procedure to obtain the system's P-invariants through objects’ P-invariants is suggested. From the P-invariants obtained, system structural properties such as deadlock and overflow can be analyzed. By using Petri net unfolding techniques and by extracting the process model of each object from the entire process model, the sequencing analysis for operations in supply chain processes becomes possible. Several manufacturing supply chain examples are used to illustrate the effectiveness of the proposed method.     

Development of two-level decision tree-based real-time scheduling system under product mix variety environment

Most of the research on machine learning-based real-time scheduling (RTS) systems has been aimed toward product constant mix environments. However, in a product mix variety manufacturing environment, the scheduling knowledge base (KB) is dynamic; therefore, it would be interesting to develop a procedure that would automatically modify the scheduling knowledge when important changes occur in the manufacturing system. All of the machine learning-based RTS systems (including a KB refinement mechanism) proposed in earlier studies periodically require the addition of new training samples and regeneration of new KBs. Hence, previous approaches investigating machine learning-based RTS systems have been confronted with the training data overflow problem and an increase in the scheduling KB building time, which are unsuitable for RTS control. The objective of this paper is to develop a KB class selection mechanism that can be supported in various product mix ratio environments. Hence, the RTS KB is developed by a two-level decision tree (DT) learning approach. First, a suitable scheduling KB class is selected. Then, for each KB class, the best (proper) dispatching rule is selected for the next scheduling period. Here, the proposed two-level DT RTS system comprises five key components: (1) training samples generation mechanism, (2) GA/DT-based feature selection mechanism, (3) building a KB class label by a two-level self-organizing map, (4) DT-based KB class selection module, and (5) DT-based dynamic dispatching rule selection module. The proposed two-level DT-based KB RTS system yields better system performance than that by a one-level DT-based RTS system and heuristic individual dispatching rules in a flexible manufacturing system under various performance criteria over a long period.     

面向钢铁企业能源流程的逐步形式化建模方法

针对钢铁企业能源流程的特点,以及以往能源建模存在的不足,提出一种从UML到Petri网模型逐步形式化的建模方法。所建模型可以通过仿真平台进行验证评估,对能源流程进一步定性和定量分析,深入理解、优化,并可以根据反馈结果对UML模型进行修改,有助于提高系统编码实现的准确性,保证工程技术人员高效建模。以炼铁系统的能源流程系统建模为例,对方法进行说明。     

进路建立过程的时间有色petri网建模与仿真

计算机联锁软件作为计算机联锁系统的核心主控软件,可靠性和安全性需建立在好的安全模型之上,提出了采用时间有色Petri网对进路建立的具体过程进行形式化建模,时间戳可以得知联锁设备的精确动作时刻以及操作持续时间,通过CPN Tools进行编辑和仿真,以VC++6.0为开发环境完成代码编写进行验证,体现时间有色Petri网描述联锁系统逻辑和性能特性的特点,以便在软件开发初期尽早发现系统的设计错误或缺陷,突出采用时间有色Petri网建模的可靠性和安全性。     

晶圆重入加工的组合设备终止暂态的调度与分析

晶圆重入是半导体组合设备加工中典型的复杂加工工艺,分析和优化暂态加工过程对于晶圆重入加工具有重要意义.为了满足加工需求和提高组合设备的加工性能,基于稳态重入加工的双臂组合设备Petri网模型和1-晶圆周期调度策略,采用虚拟晶圆的加工模式分析了系统的终止暂态过程,讨论了系统终止暂态的加工时间分布,并给出相应的解析式进行描述.利用eM-Plant仿真平台建立了重入加工的双臂组合设备终止暂态的仿真模型,并用例子验证了1-晶圆周期调度的可行性及解析式的有效性,为研究晶圆重入加工过程的优化提供了有效方法和手段.     

基于Petri网的建设工程项目实施阶段工作流建模与仿真

构建一个能够准确表达实施过程系统性、动态性和不确定性的工作流模型是实现建设工程项目实施阶段工作流管理与控制的有效途径。在对建设工程项目实施阶段工作流模型特点分析及工作流概念模型构建的基础上,基于分层赋时着色Petri网构建建设工程项目实施阶段工作流模型。通过运行该工作流模型,能够获得实施阶段的信息流、资源流、异常处理、持续时间等抽象内容,不仅为实现建设项目实施阶段的工作流管理与控制提供有力的方法支持,同时也是Petri网建模技术在建设工程领域中的应用拓广。借助CPN Tools仿真平台,以一般工业与民用建筑的实施阶段为例进行工作流模型的构建与仿真,验证了基于分层赋时着色Petri网构建建设工程项目实施阶段工作流模型的正确性和有效性。     

Software modeling and analysis using a hierarchical object-oriented Petri net

Petri net is used widely to analyze and model various systems formally. Recently, many Petri nets mania devote their efforts to enhancing and extending the expressive power of Petri nets. One such effort is to extend Petri nets with object-oriented concepts. An object-oriented paradigm provides excellent concepts to model real-world problems. Object-oriented concepts allow us to build software systems easily, intuitively, and naturally. Although several high-level Petri nets with the concept of objects are suggested, these nets do not fully support the object-oriented concepts. In this paper, we propose a hierarchical object-oriented Petri net (HOONet). The formal syntax and semantics of HOONet are explained in detail. HOONet supports a wide range of object-oriented features including abstract, encapsulated and modularized objects, object interaction by message passing, inheritance, and ploymorphism. HOONet also supports a variety of modeling and analysis mechanisms such as incremental modeling of evolving systems, unfolding the HOONet to lower level Petri net, and incremental reachability analysis for HOONet models. We demonstrate the usefulness of HOONet by applying it to modeling and analysis with an example.     

基于嵌入式马尔可夫链的网络防火墙性能建模与分析

提出了一种基于嵌入式马尔可夫链的解析排队模型来分析和研究基于一定准则的防火墙在面对正常流量和DoS攻击时的性能。基于这种排队模型,得到了一组关于防火墙特征和性能的指标计算方法,这对防火墙的设计来说具有重要意义。同时还提出了一种易于实现的算法来得到这种马尔可夫链模型的状态概率,对防火墙的状态和性能也作了深入的分析。最后通过实验分析验证了提出的解析模型的有效性。     

最小变化区域在流程建模中的应用

针对流程建模过程中缺乏合理性验证以及所建模型过于庞大导致验证复杂的问题,在研究建模过程中结构变化的基础上,提出一种将最小变化区域的思想引入到流程建模过程中的方法。对所提出的方法使用Petri网作为分析工具,以具体系统为例进行了建模应用分析,并在建模过程中进行了合理性验证。分析比较结果表明,利用最小变化区域的思想进行建模可以降低复杂度,并能够在流程建模及模型验证等方面提高工作效率。     

Stochastic optimization for real-time operation of alumina blending process

In this paper, the stochastic optimization blending operation is applied to the alumina production in this paper. A new binomial distribution based stochastic scenario optimization used together with the sample selection approach is utilized to design the optimal set point for control, under which the probability of quality indices of the raw slurry being within the tolerance region is high enough in the presence of uncertainties caused by fluctuation of the raw material and disturbances. Through practical industrial experiments, it is observed that the proposed stochastic optimization method is effective and the computational cost is low.     

并行计算的Petri网建模和FPGA实现

在分析现有Petri网建模及其FPGA实现方法的基础上, 首先探讨了并行计算的Petri网建模方法, 将并行计算任务分解成多个并行处理单元, 用IOPT网为系统进行建模; 然后提出了构造监控层和算法层的双层结构以实现模型到FPGA实现的具体映射, 有效解决了Petri网模型中变迁只能表示简单加减运算的问题。通过矩阵乘法的应用示例, 表明了上述方法的正确性和通用性。最后提出了进一步的研究方向。     

神经网络在船舶轮机训练器实时仿真建模中的应用研究

文运用反向传播 (BP)神经网络理论 ,设计了一个仿真 10 5单缸柴油机示功图的BP网络模型 ,并对之进行了讨论和研究 ,说明该神经网络模型不但可以满足船舶轮机仿真训练器的精度要求 ,并且还可以保证轮机仿真过程的实时性 ,从而提出了船舶轮机训练器实时仿真建模的又一种有效的方法     

Petri net based decision system modeling in real-time scheduling and control of flexible automotive manufacturing systems

This paper presents the design and the implementation of a Petri net (PN) model for the control of a flexible manufacturing system (FMS). A flexible automotive manufacturing system used in this environment enables quick cell configuration, and the efficient operation of cells. In this paper, we attempt to propose a flexible automotive manufacturing approach for modeling and analysis of shop floor scheduling problem of FMSs using high-level PNs. Since PNs have emerged as the principal performance modeling tools for FMS, this paper provides an object-oriented Petri nets (OOPNs) approach to performance modeling and to implement efficient production control. In this study, we modeled the system as a timed marked graph (TMG), a well-known subclass of PNs, and we showed that the problem of performance evaluation can be reduced to a simple linear programming (LP) problem with m − n + 1 variables and n constraints, where m and n represent the number of places and transitions in the marked graph, respectively. The presented PN based method is illustrated by modeling a real-time scheduling and control for flexible automotive manufacturing system (FAMS) in Valeo Turkey.     

考虑环境因素的分布式系统可靠性建模及其分析

为建立可变工作环境下分布式系统可靠性模型,提出受控混合随机Petri网,即用连续库所中的托肯控制离散变迁的变迁率．以此反映工作环境对部件可靠性的影响,从而推理出环境对系统可靠性的影响．在此模型的基础上,采用蒙特卡罗方法进行不同环境下系统可靠性仿真求解,解决了可变工作环境下分布式系统的可靠性建模及其分析问题．最后,以一个C^4ISR系统为例说明了该方法是一种考虑可变工作环境影响的分布式系统可靠性分析的可行方法．     

An analytical approach for the modeling of real-time services over IP network

The modeling and analysis of system and network performance issues are useful tools in the development and engineering processes. The analytical models have a high value in the early stages to uncover major performance problems which affect the design of the architecture before the cost of rectification is too high. The development of new modeling methods for rapid analysis is also very important for the further fast deployment of new applications and services. In this paper, we develop a modeling method, based on queuing theory, for the solution of network performance problems faced when trying to support real-time services over Internet Protocol (IP) network. Namely, we are modeling signaling network architecture for the real-time services using M/GX/1 queuing system. We evaluate and compute expected waiting time and time in system. Furthermore, we present numerical results of our calculations and provide corresponding curves for them.     

典型化工过程软硬件一体仿真系统实现

为了研究、设计和拓展过程监控系统研究的试验平台,开发了基于TE过程(Tennessee Eastman process)的软硬件一体实时仿真系统。本文对这套仿真系统的硬件构造及功能,TE过程的实时仿真数据采集、数据处理、数据图形及表格显示等功能的实现予以详细地阐述。实验表明该系统功能完善,达到了预期的教学及科研目的。     

基于资源共享的医疗服务流程的建模与仿真分析

针对目前患者到医院就诊等待时间长、医院内部资源利用效率低的问题,提出一种基于着色Petri网的医疗服务流程模型.利用仿真工具CPN Tools对整个医疗服务流程构建模型,在证明模型正确性的基础上对模型进行仿真分析与计算,获取患者就诊过程中各个环节的等待时间、被服务时间、医护人员的有效服务时间以及床位的有效服务时间等各项指标,最后通过对各项制约效率指标的分析,为资源进行合理调配,提高服务效率和资源利用率提供了理论依据.实验结果表明,该方法与以往就医模式相比,能够为流程重组及资源分配等各项优化措施提供事实数据,对同类研究具有一定借鉴意义.     

排队系统的着色Petri网建模与分析

着色Petri网（CPN）是研究离散事件动态系统的有力工具,将着色Petri网引入排队系统建模中,能弥补排队模型缺乏动态逻辑行为分析能力的不足。针对排队系统一般模型建立顶层结构模型,并对排队系统的4个要素给出了具体的CPN描述。给出一个具体实例,阐明排队系统的CPN分析法的使用,利用仿真工具CPN-Tools对模型仿真实现,仿真结果与数学模型得出的理论值对比分析,验证了可行性。