共查询到20条相似文献,搜索用时 22 毫秒
1.
Sajal K. Das Vinod K. Agrawal Dilip Sarkar Lalit M. Patnaik 《Computers & Electrical Engineering》1988,14(3-4):75-91
The use of invariants is an important tool for analysis of distributed and concurrent systems modeled by Petri nets. For a large practical system, the computation of desired invariants by the existing techniques is a time-consuming task. This paper proposes a theoretical foundation for simplified computation of desired invariants. We provide invariant-preserving Petri net reduction rules followed by the conditions for the existence of invariants in various well-structured nets. If an invariant exists, it can be found directly from the net structure using the formulas derived, or by applying the existing techniques on the reduced net. 相似文献
2.
利用原型Petri网对列车控制系统建模难于实现,用带抑止弧的增广Petri网则可以较好地描述问题。将带抑止弧的增广Petri网作为计算模型,对列车控制系统的一些关键问题进行了建模并给出了两个控制子系统:车站调度子系统与区间运行子系统。车站调度子系统实现了对列车请求进入和驶离车站的协调控制,区间运行子系统则实现了闭塞区间的车辆的安全性控制、突发事件时(如遭遇雷击,信号丢失的情况发生等)的安全性处理和公路铁路交叉口的调度等。最后,利用S-不变量对模型的活性、可达性和有界性等给予了形式化的验证。 相似文献
3.
Kramer B. Luqi Berzins V. 《IEEE transactions on pattern analysis and machine intelligence》1993,19(5):453-477
The formal semantics of a prototyping language for hard real-time systems, PSDL, is given. PSDL provides a data flow notation augmented by application-orientation timing and control constraints to describe a system as a hierarchy of networks of processing units communicating via data streams. The semantics of PSDL are defined in terms of algebraic high-level Petri nets. This formalism combines algebraic specifications of abstract data types with process and concurrency concepts of Petri nets. Its data abstraction facilities are used to define the meaning of PSDL data types, while high-level Petri nets serve to model the casual and timing behavior of a system. The net model exposes potential concurrency of computation and makes all synchronization needs implied by timing and control constraints explicit and precise. Time is treated as state of clocks, and clocks are modeled as ordinary system components. The net semantics provides the basis for applying analysis techniques and semantic tools available for high-level Petri nets 相似文献
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ST—组合Petri网的结构性质分析 总被引:2,自引:0,他引:2
本文提出ST-组合Petri网的概念,讨论了ST-组合Petri网对子网的结构性质保持问题,深入研究了ST-组合Petri网的结构活性、结构有界性,守恒性,可重复性,相容性,公平性。本文给出的网组合可作为系统合成与分析的有效方法。 相似文献
5.
Petri nets for protocol engineering 总被引:8,自引:0,他引:8
To-yat Cheung 《Computer Communications》1996,19(14):1250-1257
6.
《IEEE transactions on pattern analysis and machine intelligence》1987,(5):578-581
Timed Petri nets are useful in performance evaluation of concurrent systems. The maximum computation rate is achieved for minimal cycle time of timed Petri net. It is known that minimal cycle time problem for P-invariant Petri nets is NP-complete. In this paper we prove that the minimal cycle time problem, for non-P-invariant Petri nets and for a small subclass of P-invariant Petri nets called free-choice nets having live and safe marking, is NP-complete. 相似文献
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Xenofon D. Koutsoukos Kevin X. He Michael D. Lemmon Panos J. Antsaklis 《Discrete Event Dynamic Systems》1998,8(2):137-173
In this paper, timed Petri nets are used to model and control hybrid systems. Petri nets are used instead of finite automata primarily because of the advantages they offer in dealing with concurrency and complexity issues. A brief overview of existing results on hybrid systems that are based on Petri nets is first presented. A class of timed Petri nets named programmable timed Petri nets (PTPN) is then used to model hybrid systems. Using the PTPN, the stability and supervisory control of hybrid systems are addressed and efficient algorithms are introduced. In particular, we present sufficient conditions for the uniform ultimate boundness of hybrid systems composed of multiple linear time invariant plants which are switched between using a logical rule described by a Petri net. This paper also examines the supervisory control of a hybrid system in which the continuous state is transfered to a region of the state space in a way that respects safety specifications on the plant's discrete and continuous dynamics. 相似文献
9.
To better understand the relationships between different models of parallel computation, we introduce a new computation system formulation and develop general notions of homomorphisms and isomorphisms between computation systems. This allows us to study relations between vector addition systems, vector replacement systems, Petri nets, and generalized Petri nets. Results in this paper that may be of particular interest include a long list of properties preserved under homomorphism, and constructions that show that vector replacement systems can be simulated by vector addition systems, and that generalized Petri nets can be emulated by Petri nets. 相似文献
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Juan L.G. Guirao Fernando L. Pelayo Jose C. Valverde 《Computers & Mathematics with Applications》2011,61(5):1402-1406
This paper presents a very first step on the road to applying the theory of discrete dynamical systems (DDSs) in the analysis of concurrent computing systems. In order to proceed, Petri nets (PNs) are appropriately modeled as DDSs, so defining the corresponding phase space with its metric structure and the evolution operator of the system. We conclude this study by showing results for some identifiable problems. 相似文献
12.
《Computers & Mathematics with Applications》1999,37(11-12):191-206
It is shown that a large class of flexible manufacturing cells can be modeled using timed Petri nets. Net models of simple schedules (i.e., schedules in which exactly one part enters and one leaves the cell during each cycle) are conflict-free nets. Two complementary approaches to analysis of such models are presented: invariant analysis and throughput analysis. Invariant analysis provides analytic (or symbolic) solutions for the cycle time of a cell analyzing (invariant) subnets of the original net. Throughput analysis performs a series of performance-preserving net reductions to simplify the original model. Several directions for further research are indicated. 相似文献
13.
ZhiWu Li MengChu Zhou 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》2008,38(3):667-679
As a structural object, siphons are well recognized in the analysis and control of deadlocks in resource allocation systems modeled with Petri nets. Many deadlock prevention policies characterize the deadlock behavior of the systems in terms of siphons and utilize this characterization to avoid deadlocks. This paper develops a novel methodology to find interesting siphons for deadlock control purposes in a class of Petri nets, i.e., a system of simple sequential processes with resources . Resource circuits in an are first detected, from which, in general, a small portion of emptiable minimal siphons can be derived. The remaining emptiable ones can be found by their composition. A polynomial-time algorithm for finding the set of elementary siphons is proposed, which avoids complete siphon enumeration. It is shown that a dependent siphon can always be controlled by properly supervising its elementary siphons. A computationally efficient deadlock control policy is accordingly developed. Experimental study shows the efficiency of the proposed siphon computation approach. 相似文献
14.
Fuzzy multimodel of timed Petri nets 总被引:1,自引:0,他引:1
Hennequin S. Lefebvre D. El Moudni A. 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2001,31(2):245-251
15.
Young Chan Kim Tag Gon Kim 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》1996,26(4):599-605
Petri nets are a powerful modeling tool for studying reactive, concurrent systems. Analysis of the nets can reveal important information concerning the behavior of a modeled system. While various means for the analysis of the nets has been developed, a major limitation in the analysis, is explosion of large states space in simulation. An efficient method to manage large states space would overcome such a limitation. This paper proposes a framework for the modeling and analysis of Petri nets using relational database technologies. Formalism of the framework is based on a bag-theoretic relational algebra extended from the conventional, Within the framework, Petri nets are formalized by bag relations, and analysis algorithms are developed based on such formal relations. Properties associated with the nets are formalized by queries described in terms of the bag-theoretic relational algebra. The framework has been realized in a commercial relational database system using a standard SQL. 相似文献
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A Survey of Petri Net Methods for Controlled Discrete Event Systems 总被引:14,自引:2,他引:14
This paper surveys recent research on the application of Petri net models to the analysis and synthesis of controllers for discrete event systems. Petri nets have been used extensively in applications such as automated manufacturing, and there exists a large body of tools for qualitative and quantitative analysis of Petri nets. The goal of Petri net research in discrete event systems is to exploit the structural properties of Petri net models in computationally efficient algorithms for computing controls. We present an overview of the various models and problems formulated in the literature focusing on two particular models, the controlled Petri nets and the labeled nets. We describe two basic approaches for controller synthesis, based on state feedback and event feedback. We also discuss two efficient techniques for the on-line computation of the control law, namely the linear integer programming approach which takes advantage of the linear structure of the Petri net state transition equation, and path-based algorithms which take advantage of the graphical structure of Petri net models. Extensions to timed models are briefly described. The paper concludes with a discussion of directions for future research. 相似文献
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Patrice Bonhomme 《Discrete Event Dynamic Systems》2013,23(2):197-209
Petri nets are a powerful formalism for the specification and verification of concurrent systems, such as sequential systems and manufacturing systems. To deal with real-time systems whose time issues become essential, different extensions of Petri nets with time have been proposed in the literature. In this paper, a new scheduling and control technique for real-time systems modeled by ordinary P-time Petri nets is proposed. Its goal is to provide a scheduling for a particular firing sequence, without any violation of timing constraints ensuring that no deadline is missed. It is based on the firing instant notion and it consists in determining an inequality system generated for a possible evolution (in terms of a feasible firing sequence for the untimed underlying Petri net) of the model. This system can be used to check reachability problems as well as evaluating the performances of the model considered and determining the associated control for a definite functioning mode and it introduces partial order on the execution of particular events. 相似文献
20.
D. A. Zaitsev 《Cybernetics and Systems Analysis》2004,40(2):226-237
A linear fundamental equation for a timed Petri net is constructed. Full and partial invariants of state and behavior of a timed Petri net are introduced. Properties of invariant nets are analyzed. Interrelations of full and partial invariants are shown. Examples of analysis of net models of production systems and processes are described. 相似文献