A New Simulation Method Using Multithreading for Modeling Parallel Operated Systems

摘要

This paper summaries a new method using multithreading and timed Petri Nets (TPN) in modeling and controlling a Parallel Operated System (POS) for Internet users. In addition, the standard clock method is used to trigger the event in the TPN model. The POS in the Laboratory Centre consists of a central controller, an automatic storage and retrieval system with input and output buffers (ASRS), an automatic guided vehicle (AGV) and two Computer Numerical Controlled (CNC) machines with input and output buffers which are represented in respective objects. In Java programs, class members are built with attributes and methods to represent the individual components of the POS. Each of these objects is implemented by making an instance of a respective class member and running it as one of the multiple threads. Coordinating actions between different objects is essential and it is often the case that these activities are time-related. Simulations of actions between these objects benefit by threading because they often model autonomous and interacting entities. The advantages of the proposed method of modeling the POS are that the simulation models can simultaneously provide control capabilities as well as implement the scheduling strategy. The users can use the simulation models through the Internet because the modeling method is relatively simple and the simulation is comparatively fast in Internet applications.