This dissertation is concerned wiyh the research on the theory and methods of PN machines for discrete event dynamic systems. The content of the whole disertation is divided into eight chapters. Chapters 1 reviews the research work around the world. Chapter 2 introduces some basic concepts of formal language and Petri net. In chapters 3, The PN machine models are established. The some forms of PN machine are discussed. The properties of PN language are studied. The concept of vector grammars under the string semantic is introduced. The class of vector grammars is gived, which is similar to the class of Chomsky grammars. The regular vector grammar is devided further. The hybrid PN machine is introduced, and its language is proved equivalent to the language of the language of the context-free vector grammar. So the perfect relation structure between vector grammars and PN machines in formed. In Chapters 4, an algorithm for computing effective and repeatable vectors of a canonical PN manchine, as well as minimum T-invariants which make it possible to decide the fairness of a PN machine is proposed. A sequence recognizing algorithm for PN language based on retraceable search technology is presented. Based on sequence partition and synchronous decomposition, two parallel recognizing algorithms for PN machine are presedted, respectively. In chapter 5, the concept of a behavior expression language which is used as a formalization of a behavior of concurrent system is introduced. It is shown that any a behavior expression language may be generated by a safe PN machine. A transform algorithm from behavior expression to a safe PN machine is presented.In chapter 6,three kinds of hierarchy operations and three kinds of embbedded operations of PN machines are studied. These operations' preserving properties for language, liveness, fairness as well as repetition are discussed. Based on these operations, the design method of object to behavior of decrete concurrent systems is given..In chapter 7,according to the character of practical system, two useful composition operations of PN machines are induced. The first kind of operation is synchronous composition with transition as object. The second of operation is share composition with place as object. The new concepts behavior and state invariants in operation process are definted.The invariant relations for two kinds of operations are studied. These theorems can be used to the composition of large systems. On the other hand, the language characterizations for weak liveness(free-deadlock) and liveness of PN machines are given. In terms of these characterizations, (weak) liveness of systems can be tested.An efficient method for system desig, analysization and control is obtained. In chapter 8, based on behavior expression, a new analysis method of systems performance is presented. It can be used for arbitrary distributed stochasti
修改评论