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.     

价格着色Petri网在工作流建模中的应用

在着色网的基础上扩展了价格信息,提出了价格着色网,用来对业务流程进行价格建模并对其作相应的成本预算分析.其中讨论了价格着色网的变迁步规则,提出了价格着色网中的标识--经济标识的定义,并有针对性地提出了最小成本构造算法.最后以一个业务流程实例演示了该模型的应用,得出结论为价格着色网能够较好地解决业务流程建模中的成本预算分析问题而且该模型中的最小成本构造算法是有效的.     

A Petri net synthesis theory for modeling flexible manufacturingsystems

A theory that synthesizes Petri nets for modeling flexible manufacturing systems is presented. The theory adopts a bottom-up or modular-composition approach to construct net models. Each module is modeled as a resource control net (RCN), which represents a subsystem that controls a resource type in a flexible manufacturing system. Interactions among the modules are described as the common transition and transition subnets. The net obtained by merging the modules with two minimal restrictions is shown to be conservative and thus bounded. An algorithm is developed to detect two sufficient conditions for structural liveness of the net. The algorithm examines only the net's structure and the initial marking, and appears to be more efficient than state enumeration techniques such as the reachability tree method. In this paper, the sufficient conditions for liveness are shown to be related to some structural objects called siphons. To demonstrate the applicability of the theory, a flexible manufacturing system of a moderate size is modeled and analyzed using the proposed theory.     

Deadlock avoidance schemes in a distributed robotic system: Petri net modeling and analysis

This article presents a Petri net-based approach to modeling and evaluating four different deadlock avoidance schemes for a distributed robotic system, i.e., a five-robot-five-assembly-line system. Among these four schemes are the conventional, full synchronization, global semaphore, and partial synchronization schemes. To explore such issues as the system performance and control structure complexity, this article conducts detailed Petri net modeling for this system and evaluates performance of the deadlock avoidance schemes using stochastic Petri nets. The interesting results presented include that: (1) any possible system deadlock can seriously degrade the system performance even if effective deadlock resolution techniques are available; (2) conservative use of resources is likely to be the best policy; and (3) higher resource utilization may not necessarily imply higher system production rate in a resource-sharing environment. The related results need to be further explored for the larger resource-sharing discrete event systems. © 1995 John Wiley & Sons, Inc.     

Petri net modeling and deadlock analysis of parallel manufacturing processes with shared-resources

Multiple resource-sharing is a common situation in parallel and complex manufacturing processes and may lead to deadlock states. To alleviate this issue, this paper presents the method of modeling parallel processing flows, sharing limited number of resources, in flexible manufacturing systems (FMSs). A new class of Petri net called parallel process net with resources (PPNRs) is introduced for modeling such FMSs. PPNRs have the capacity to model the more complex resource-sharing among parallel manufacturing processes. Furthermore, this paper presents the simple diagnostic and remedial procedures for deadlocks in PPNRs. The proposed technique for deadlock detection and recovery is based on transition vectors which have the power of determining the structural aspects as well as the process flow condition in PPNRs. Moreover, the proposed technique for dealing with deadlocks is not a siphon-based thus the large-scale PPNRs for real-life FMSs can be tackled. Finally, the proposed method of modeling and deadlock analysis in the FMS having parallel processing is demonstrated by a practical example.     

无线通信系统的Petri网建模与分析

无线通信系统是一个分布式实时多任务数据处理系统,具有实时性、并发、异步和多任务等特点.Petri网是描述和分析异步并发现象的一种有效的模型工具.以Petri网为工具,建立了无线通信系统的仿真模型,对其功能和数据流进行模拟,并对其结构性能、任务的忙闲程度、死锁进行了定性分析,实现了模型和程序结构的自动转换,从一个全新角度对无线通信系统进行了分析和评价.     

Neuron type processor modeling using a timed Petri net

The basic operation of a digital neuron is reviewed, and the theory of time Petri nets used for modeling, representation, and analysis of the neuron-type processor (NTP) is reviewed. The timed Petri net is utilized to produce a model for the digital NTP. The neuron-type processor performs input temporal and spatial summation, as well as thresholding. The timed Petri net of the NTP operates asynchronously and sequentially takes on a series of distinct internal states, so that each of these states can concurrently realize a distinct set of steering switching functions depending on the pattern of steering inputs applied to it at the time. This model is structured using several subnets, called essential module units. Depending on the desired number of input dendrites required for the NTP, the essential module units (EMU) are interconnected to produce the required timed Petri net. The timed Petri net and representation facilitates a method of analysis of neural net works containing NTPs prior to hardware implementation.     

道路交通信息分析与建模

交通流速度.流量和密度是道路交通信息的主要参数,分析参数的特性并对其建模是研究交通信息重要部分.以浮动车和线圈采集的数据为研究对象,基于小波技术对数据除去噪声,并通过线性回归预测误差的衰减率选取合适的拟合阶数,从而运用线性回归方法对数据进行拟合.最后对北京市区某道路的采集数据进行分析,结果表明该模型具有可行性和有效性.     

Supervisory control of a multi-echelon supply chain: A modular Petri net approach for inter-organizational control

Petri nets (PNs) are frequently utilized to model system dynamics due to their ability to handle concurrencies and sequential dependence. In this paper, a portion of the supply chain operations reference (SCOR) model has been extracted and modeled using PNs for the purpose of exerting supervisory control upon a multi-echelon supply chain (SC). The activities of source, make and deliver, inherent in the SCOR model form the basis of the representation of the PN model for each echelon considered in the SC model. Two control nets are utilized: one above the base model of each echelon to exert local constraints and an enterprise level supply chain manager (SCM). The local constraints are at the tactical and operational levels while the SCM enforces additional constraints consisting of long term planning goals at the strategic level. Place invariants are used to create the supervisors. Performance measures of the total SC are formulated to determine the effectiveness of any partnership. An efficient method for finding the current state of the system is developed which is used to determine the performance measures of each echelon. This paper presents a modular approach to the overall structure and PN modeling for a SC system. It is intended to extend the use of supervisory control from a shop-floor level to an inter-organizational facility and enterprise level.     

虚拟制造企业的Petri网建模/仿真

为降低Petri网建模难度并增强模型的可读性,提出一种通过消息序列表（Message Sequence Chart,MSC）模型对虚拟制造（Virtual Manufacturing,VM）企业的生产经营过程进行Petri网建模的新方法．建立冲突消解机制,给出从MSC模型到Petri网模型的转换算法,在不改变Petri模型活性、安全性和有界性等特性的基础上对其进一步优化,并对Petri网模型进行分析与评估．     

基于Petri网理论的计算机网络性能分析和电子商务模型设计

本文采用Petri网作为建模求解工具,揭示TCP网络的实质,探讨TCP网络的性能分析问题和电子商务系统中的买方和卖方模型设计问题。最后对全文进行了概括性总结,并指出了理论和应用上有待进一步研究的问题。     

Stochastic Petri net analysis of a replicated file system

The authors present a stochastic Petri net model of a replicated file system in a distributed environment where replicated files reside on different hosts and a voting algorithm is used to maintain consistency. Witnesses, which simply record the status of the file but contain no data, can be used in addition to or in place of files to reduce overhead. A model sufficiently detailed to include file status (current or out-of-date) as well as failure and repair of hosts where copies or witnesses reside, is presented. The number of copies and witnesses is not fixed, but is a parameter of the model. Two different majority protocols are examined     

Investigating single-type structural elements of a component Petri net during component modeling and analysis of a complex system with parallelism

The process of modelling reactive distributed systems by a component Petri net (a CN-net) is considered. A mechanism for constructing composite components (places and transitions) of a CN-net is shown, and an analysis of a CN-net is demonstrated by the example of modelling the railroad traffic pattern at a railroad junction. A relationship between incidence matrices of composite components of the same type in a CN-net is established, which allows one to substantiate the possibility of studying only one simplest representative of such components to verify a model of a system.     

着色Petri网在科技计划项目管理系统建模中的应用

在深入研究科技计划项目管理业务基础上,鉴于Petri网的特点,提出了利用着色Petri网建模科技计划项目管理系统的方法.分析了着色Petri网适合于系统建模的原因,以项目管理评审环节为例讨论了着色Petri网在建模中的应用,并建立了基于着色Petri网的系统模型.通过对该模型的分析仿真结果表明,该方法是可行和有效的.     

Petri net modeling and scheduling for cyclic job shops with blocking

Cyclic scheduling is an effective scheduling method in the repetitive discrete manufacturing environment. We investigate the scheduling problem for general cyclic job shops with blocking where each machine has an input buffer of finite capacity. We develop Petri net models for the shops. We propose a sequential buffer control policy that restricts the jobs to enter the input buffer of the next machine in a specified sequence. We show that the scheduling model of a cyclic shop with finite buffers under such a buffer control policy can be transformed into a scheduling model of a cyclic shop with no buffer that can be modeled as a timed marked graph. In addition, we characterize the structural properties for deadlock detection. Finally, we present a mixed integer programming model to find an optimal deadlock-free schedule that minimizes the cycle time.     

A traffic analysis attack to compute social network measures

The development of digital media, the increasing use of social networks, the easier access to modern technological devices, is perturbing thousands of people in their public and private lives. People love posting their personal news without consider the risks involved. Privacy has never been more important. Privacy enhancing technologies research have attracted considerable international attention after the recent news against users personal data protection in social media websites like Facebook. It has been demonstrated that even when using an anonymous communication system, it is possible to reveal user’s identities through intersection attacks or traffic analysis attacks. Combining a traffic analysis attack with Analysis Social Networks (SNA) techniques, an adversary can be able to obtain important data from the whole network, topological network structure, subset of social data, revealing communities and its interactions. The aim of this work is to demonstrate how intersection attacks can disclose structural properties and significant details from an anonymous social network composed of a university community.

     

基于彩色Petri网的工作流权限管理的建模与分析

在一个组织中,权限管理是个非常复杂而又重要的任务。为确保组织的业务过程中各项任务只能被合法的用户所执行,建立授权模型并验证权限分配的正确性是十分必要的。彩色Petri网具有比Petri网更强的表达能力,可以用来建立一个完整的权限管理模型,不仅包含权限管理,还包含安全约束如SoD（职责分离）以及角色层次关系结构（role hierarchy）等概念。使用Petri网建模的一个优势是它建立在坚实的数学基础之上,并且得到了许多分析验证技术和工具的支持,如使用线性代数技术分析授权状态的可达性。     

基于Petri网的单向PWM整流电路建模

PWM整流电路是交-直-交变流器的重要电路,是包括连续和离散事件的混杂系统,具有并发、异步等特点。Petri网是描述和分析异步并发现象的一种有效的混杂系统建模工具。本文以Petri网为工具,从一个全新角度,建立单相PWM整流电路的模型,对其电路特性进行了分析。     

Design and implementation of a Petri net based toolkit for Adatasking analysis

The use of Petri nets for defining a general static analysis framework for Ada tasking is advocated. The framework has evolved into a collection of tools that have proven to be a very valuable platform for experimental research. The design and implementation of tools that make up the tasking-oriented toolkit for the Ada language (TOTAL) are defined and discussed. Modeling and query/analysis methods and tools are discussed. Example Ada tasking programs are used to demonstrate the utility of each tool individually as well as the way the tools integrate. TOTAL is divided into two major subsystems, the front-end translator subsystem (FETS) and the back-end information display subsystem (BIDS). Three component tools that make up FETS are defined. Examples demonstrate the way these tools integrate in order to perform the translation of Ada source to Petri-net format. The BIDS subsystem and, in particular, the use of tools and techniques to support user-directed, but transparent, searches of Ada-net reachability graphs are discussed