A practical module-based simulation model for transportation-inventory systems

A method of modeling transportation-inventory systems is proposed in an attempt to flexibly describe the systems in which a lot of kinds of items are ordered to transport, transported, stored at the warehouses, and delivered to the customers. The system consists of a number of "sources" and "sinks". However, the problem considered in this study is totally different from the traditional transportation problem in terms of linear programming. Firstly, any number of different kinds of items can be treated for analysis. Secondly, any size of transportation trucks can be specified to transport items for any number of the source-sink combinations. In other words, the capacity of the transportation truck is to be specified in building a simulation model. In addition, any number of both sources and sinks can be specified as required to build a simulation model. Thirdly, the order by a sink is made toward the associated source, based on the inventory policy at the sink, and the "pull system" is adopted in the demand-supply environment. An efficient module based modeling method is proposed to generate simulation models for the above mentioned transportation-inventory systems. The proposed method is applied to the actual system. It is found that the time to build simulation models could be drastically reduced. Furthermore, the proposed method is found to be both practical and powerful.