| Discrete event systems are widely applied in our production and life, whose feature is that state variable of system is discrete, it means that state may change only at discrete points. The transformation of discrete event results in system transformation, at the same time, moment at which discrete event occur is random, effect are also. So it is impossible to give diagnosis of discrete event system by common tools and ways of mathematic. But computer simulation is considered the best way to do it.In the discrete event virtual system, how to describe efficiently and model discrete event system is very important. After researching oriented object method and on the basis of time Petri nets, the model on the basis of Petri nets is advanced, the character of layer and module is applied in the model. This paper provides an introduction to the main concept of discrete event system and surveys the abstract model of the discrete event system. Active object and time stamp are added in the Petri nets when discrete event system is analyzed and logically abstracted, which make model simple and visual. After the model is built up, Layer and oriented-object are synthetically used, property of Petri net is available. Discrete event algorithm is changed from traditional event-driver to new method, which domains on active object, assists in time. Active objects which are managed by simulated queue are orderly executed, which seems real scene and enhances system simulation.The model has been used in the process of developing computer organized component virtual experiment, the result shows that speed of simulation and effect on reality are good, it has good practicality. This type of modeling is applicable to some real-world problem, the model can provide some suggestion for other discrete event system. And provide a new view for related researcher. Additionally, the model can be simply applied in the environment of distributed system and single process unit system. |
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