Modeling And Simulation Of Container Terminal Logistics System Based On WITNESS

Container terminal logistics is an organic system, made of interactive and dynamic components, such as containers, ships, berths, yards, tracks, quay cranes and yard cranes, trucks, labors and communications, in a limited terminal space. Since container terminals play a fundamental role in the container transportation to ensure a smooth transfer between different modes of transport, it is very important in internal and international trade. Because of the fast-developing global containerization, most of container ports are facing great challenges and chances.Combined with Ministry of Education's important scientific and technological project "Research on the Machinery Allocation and Supervision System of Container Yards Based on Wireless Local Networks", this paper does research on the theoretical methods on the scheduling and simulation of container terminal logistics systems, and put forward some methods to improve the operational efficiency of this system.At the beginning of the paper, a literature review on the domestic and abroad researches of container terminal logistics system is provided; A Petri-net based idea to model the whole container terminal logistics system is put forward; then the paper introduces the basic components, layout, loading and unloading process flow of container terminals, evaluates the related performance parameters and at last introduces some related experience formulas based on the historical data of an actual terminal.After going over the basic theoretical principles of Petri-net, the paper analyzes the exiting problems such as "block" of basic Petri-net, then introduces a compound modeling idea, makes a hierarchical and dynamic model of container terminal logistics system with the four sub-models of collecting containers, unloading ships, loading ships and picking up containers, and summaries their events-changing list.According to the idea of the finished Petri-net model and the process characteristics and simulation aims of container terminals, a computer simulationmodel of container terminal logistics system is made based on the software of WITNESS and is validated by the data of an actual terminal. At last the model is used to analyze the present productivity of an actual container terminal and the bottleneck of its logistics system after the terminal is expanded, and provides the decision support for the terminal.