TIMED PETRI NETS: THEORY AND APPLICATION

by: Jiacun Wang, Kluwer Academic Publishers, 1998

PREFACE

Driven by the request for increased productivity, flexibility, and competitiveness, increasingly modern civilization has created high-performance discrete event dynamic systems (DEDS’s). These systems exhibit concurrent, sequential, competitive activities among their components. They are often complex and large in scale, and necessarily flexible and thus highly capital-intensive. Examples of systems are manufacturing systems, communication networks, traffic and logistic systems, and military command and control systems. Modeling and performance evaluation play a vital role in the design and operation of such high performance DEDS’s and thus have received widespread attention of researchers in the past two decades. One methodology resulting from this effort is based on timed Petri nets and related graphical and mathematical tools.

The popularity that Petri nets have been gaining in modeling of DEDS’s is due to their powerful representational ability of concurrency and synchronization, while these properties of DEDS’s can not be expressed easily in traditional formalisms developed for analysis of "classical" systems with sequential behaviors.

By cooperating time variables into Petri nets, timed Petri nets further allow us to derive production cycle time, identify bottleneck workstations, verify timing constraints, and so on, in and for modeled DEDS’s when the time variables are deterministic. They can also be used to obtain production rates, throughput, average delays, critical resource utilization, reliability measures, and so on, for the modeled DEDS’s when the time variables are random.

There are a large number of papers dedicated to the theories and applications of timed Petri nets, but they are scattered on hundreds of journals or conference proceedings, and often lack of unity in concepts, notations, and terminologies. This makes it very difficult for new researchers and practicing engineers to understand the potential applications of timed Petri nets due to mathematical complexity and the various interpretations presented by different authors. This book aims at introducing the theories and applications of timed Petri nets systematically. Moreover, this book also presents many practical applications in addition to theoretical developments. It presents the latest research results and industrial applications of timed Petri nets.

Book Layout

Chapter 1 first examines the characteristics and available performance models of and for DEDS’s, then presents the merits of timed Petri nets for the modeling and analysis of DEDS’s, and gives the classification of various types of timed Petri net models in common use.

Chapter 2 introduces the fundamentals of Petri nets, including the definition, basic terminologies, transition firing rules, representational power, properties, and analysis methods of Petri nets. The basic concepts given in this chapter are used throughout the book.

Chapter 3 focuses on the definition, analysis method, and application of deterministic timed transition Petri nets. It also gives a brief introduction to deterministic timed places Petri nets and deterministic timed arcs Petri nets.

Chapter 4 addresses time Petri nets. The enumerative analysis technique and a set of reduction rules for time Petri nets are presented; the compositional time Petri net models and their applications to command and control systems and flexible manufacturing systems are also given.

Chapter 5 first discusses the definition, firing policies, memory properties, and the corresponding stochastic processes of stochastic timed Petri nets. After a brief review of continuous time Markov chain and queuing networks, it then introduces stochastic Petri nets and analysis techniques.

Chapter 6 pays attention to generalized stochastic Petri nets. Three kinds of analysis methods for GSPN models, the net-level aggregation technique, and the hierarchical time-scale decomposition approach for a class of GSPN models are addressed. The application to the protocol of Ethernet is also presented.

Chapter 7 describes the theory and application of two types of high-level stochastic Petri nets: colored stochastic Petri nets, and stochastic high-level Petri nets.

Chapter 8 addresses two types of semi-Markovian SPN models: extended stochastic Petri nets and deterministic-stochastic Petri nets.

Chapter 9 explores the analysis technique of arbitrary stochastic Petri net. It gives a detail description of the hybrid state analysis method.

Audience

The book serves two natural groups:

  1. faculty, staff, and graduate students who are interested in research and teaching in (timed) Petri nets and performance models for discrete event dynamic systems; and
  2. performance modeling engineers and managers responsible for the design and efficient operation of automated production systems, flexible manufacturing cells, flexible assembly station, and computer integrated systems and networks.

CONTENTS

PREFACE

bullet INTRODUCTION 1
bullet Discrete Event Dynamic Systems 1
bullet Performance Models for Discrete Event Dynamic Systems 2
bullet Timed Petri Nets: A Powerful Tool 4
bullet PETRI NETS 9
bullet Preliminary Definitions 9
bullet Transition Firing 11
bullet Representational Power 13
bullet Properties of Petri Nets 15
bullet Reachability 15
bullet Boundedness and Safeness 17
bullet Conservativeness 18
bullet Liveness 19
bullet Analysis of Petri Nets 20
bullet The Coverability Tree 21
bullet Incidence Matrix and State Equation 24
bullet Invariant Analysis 29
bullet Simple Reductions for Analysis 32
bullet Simulation 34
bullet DETERMINISTIC TIMED PETRI NETS 37
bullet Deterministic Timed Transitions Petri Nets 38
bullet Performance Analysis 40
bullet Consistent Petri Nets 41
bullet Decision-Free Petri Nets 42
bullet Performance Evaluation 43
bullet Safe Persistent Petri Nets 50
bullet Other Types of Deterministic Timed Petri Nets 53
bullet Deterministic Timed Places Petri Nets 53
bullet Deterministic Timed Arcs Petri Nets 57
bullet TIME PETRI NETS 63
bullet Time Petri Nets 64
bullet Time Petri Nets 64
bullet States in a Time Petri Net 66
bullet Enabling and Firing Conditions of Transitions 67
bullet Firing Rule between States 67
bullet Multiple Enablings of Transitions 69
bullet An Enumerative Method for Analysis of Time Petri Nets 70
bullet Informal Introduction to State Classes 70
bullet Formal Definition of the Behavior of Time Petri Nets 75
bullet Reduction of Time Petri Nets 79
bullet Equivalence of Two Time Petri Nets 79
bullet Serial Fusion 80
bullet Pre-fusion 84
bullet Post-fusion 85
bullet Lateral Fusion 86
bullet Compositional Time Petri Net Models 90
bullet Compositional Time Petri Net Models 90
bullet Component-Level Reduction Rules 93
bullet Analysis of Compositional Time Petri Net Models 102
bullet Applications of Compositional Time Petri Net Models 103
bullet Modeling and Analysis of A Command and Control System 103
bullet Modeling and Analysis of A Flexible Manufacturing System 116
bullet SHOCHASTIC TIMED PETRI NETS AND STOCHASTIC PETRI NETS 125
bullet Stochastic Timed Petri Nets 125
bullet Next Transition to Be Fired 126
bullet Memory Properties 129
bullet The Stochastic Process Associated with STPN’s 131
bullet Continuous Time Markov Chains 133
bullet Queuing Networks 137
bullet Queues 137
bullet Queuing Network 138
bullet Stochastic Petri Nets 139
bullet Stochastic Petri Nets 140
bullet Performance Evaluation 143
bullet Production Form Solution for Stochastic Petri Nets 147
bullet The Algebraic-Topological Approach 147
bullet A Net Level Characterization of the Algebraic-Topological Approach 151
bullet GENERALIZED STOCHASTIC PETRI NETS 155
bullet Generalized Stochastic Petri Nets 155
bullet Analysis of Generalized Stochastic Petri Nets 157
bullet Method I — Extension of the Method for SPN’s 158
bullet Method II — Embedded Markov Chain 159
bullet Method III — State Aggregation 168
bullet Aggregation of Generalized Stochastic Petri Nets 175
bullet Time-Scale Decomposition of Generalized Stochastic Petri Nets 180
bullet Generalized Stochastic Petri Net Model of Ethernet 184
bullet Frame Transmission in Ethernet Data Link Specification 184
bullet Generalized Stochastic Petri Net Model 186
bullet Transmission Firing Rates and Switch Probability 189
bullet HIGH-LEVEL STOCHASTIC PETRI NETS 195
bullet Colored Stochastic Petri Nets 195
bullet Colored Petri Nets 196
bullet Colored Stochastic Petri Nets 201
bullet Stochastic High-Level Petri Nets 205
bullet Predicate/Transition Petri Nets 206
bullet Stochastic High-Level Petri Nets 207
bullet SEMI-MARKOVIAN STOCHASTIC PETRI NETS 213
bullet Extended Stochastic Petri Nets 213
bullet Extended Stochastic Petri Nets 213
bullet Analysis of Extended Stochastic Petri Nets 215
bullet Analysis of Extended Stochastic Petri Nets Based on Moment Generating Functions 221
bullet Moment Generating Functions and Transfer Functions 223
bullet Procedure for System Performance Evaluation 226
bullet Petri Nets with Deterministic and Exponential Firing Times 234
bullet ARBITRARY STOCHASTIC PETRI NETS 241
bullet Arbitrary Stochastic Petri Nets and Hybrid State Probability Density Functions 241
bullet Division of Enabled Transition Set in a Given Marking 242
bullet Hybrid State Probability Densities of An ASPN 244
bullet Computation of Hybrid State Probability Densities 245
bullet Hybrid State Probability Densities of Acyclic Arbitrary Stochastic Petri Nets 251
bullet Cyclic Nets and Acyclic Nets 252
bullet Level Division of Reachability Set 253
bullet Computation of Hybrid State Probability Densities of Acyclic ASPN’s 255
bullet Time Delay Analysis of Arbitrary Stochastic Petri Nets 259
bullet Time-Delay Nets 259
bullet Computation of Time Delay Probability Density 261

BIBLIOGRAPHY 263

INDEX 275

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