| Since 1950s , the world container shipping was developing very fast. With the globalization of economy, it was increasingly obvious that container shipping played an important role in the world economy and trade. So, many countries all invested a great deal of money and other things to develop container shipping. Together with the developing of it, the problem of collection and allocation of empty containers also increasingly stood out. The study or research of collection and allocation of empty containers was always greatly thought much by theory circles and practice organizations.How to perfectly deal with the problem of collection and allocation of empty containers is the greatly important question for study in pursing container shipping. One main notable characteristic of container shipping is the big investment, which not only needs a certain scale of container fleet, but also has to build container decks , all kinds of inland depots , and must set up perfect collection and allocation system. For container shipping companies , it is necessary to buy container ship and be equipped with certain containers. These will cost them a lot of money. The investment of buying containers is fixed assets investment, but the transport freight is payout of variable cost including the fare of container collection and allocation. These fares change frequently together with container shipping freight, fuel cost , tariff ,and so on.. It is the big and difficult problem to container shipping companies.The turnover of container must include the process of unloading and loading. Unloading and loading often happen in different places. So every day, there are a lot of empty containers moving from the place which has plenty empty containers to the place which needs empty containers . Low efficiency of planning collection and allocation of empty container will waste a lot of empty resources, and it will make the relative costs increase, which will also bring profound and lasting effect to economic situation of container shipping .The ability of container liners' collection and allocation of empty container directly affects the number of equipped containers of a line and the number of lease containers, and then the container transport costs.So the world container shipping industry attached importance to this problem. Many people wanted to manage collection and allocation of emptycontainer by improving management of their enterprises and working efficiency through the way of working experience. Some people applied line planning (LP) of Operation Research to handle this problem. They built LP model of collection and allocation of empty container and got the results from the model. But this method had its shortcomings. It must take into account many factors. There were many variables . And these variables almost were static variables. The restricted equations were difficult. It could not deal with the dynamic changing problems. So we must develop a new good method to deal with this problem. This paper has given a detail description about further exploration of this problem, and has achieved valuable results.ExSpect, Executable Specification Tool, is a powerful business tool giving organisations the ability to model, monitor and analyse business processes effectively and efficiently. ExSpect offers the potential for every conceivable kind of simulation and so helps you reach decisions on cost reductions and large-scale infrastructure investment program's. ExSpect has a full-graphic user-interface and a sound formal basis, developed in close co-operation with Eindhoven University of Technology, since 1980. The entry last updated is 2000/6/13. An advantage of ExSpect is that it is possible to use application libraries specifically prepared for particular fields. Libraries are available for workflow, logistics, administrative processes and more specific business situations.Petri Nets can support can High-level Petri Nets, Place/Transition Nets, Stochastic Petri Nets, Petri Nets with Time, Hierarchy in modeling, etc..The th... |
