Optimization Of Container Loading/unloading Integrated Scheduling In A Container Terminal Based On Hybrid Flowshop

As a hub for container transport, container terminal is an important logistics nodes, linking container transport by water and on land. In order to improve service levels and economic benefits, Container terminal must make full use of a variety of loading and unloading terminal resources to conduct a reasonable scheduling job to improve the terminal’s operational efficiency. At present, although many scholars have done a great deal of research on the container terminal scheduling problem, how to effectively deal with various constraints and complexity of the relationship between the operating system and how to achieve synergy between all aspects of scheduling problem has never been solved well.According to the reality of the container terminal and the current study, this paper mainly studys on the following aspects.The first is to propose reasonable assumptions to simplify the problem. This paper establishs a three-phase integer programming model on container terminal operating system. The goal is to minimize the maximum operating time. This paper described the constraints of reality with mathematical formulas, in order to reflect interoperability and conditionality of the various components in the operating system. The second is to solve the model. The model of container terminal operations is simplified for the hybrid flow shop model.And the paper takes two steps to achieve solution. The first step is to transfer the three-phase problem into two phases under the assumption that the number of container trucks is sufficient. The study object is job blocks divided on the base of the bay and the type of job. Using Johnson heuristic algorithm, the result——operating order of the job blocks is achieved. The second step is truck assignment. In the assignment process, the operating block is splited for single containers, so that the trucks will not be limited to transport the containers unloaded by only one quay crane, but can be shared by different "operating line", thus to improve truck utilization.The second is to optimize trucks’ transport path when two vessels load and unload simultaneously after the sequence of loading and unloading is determined, in order to further improve operating efficiency and equipment utilization. First, the paper establishes a mathematical model of trucks transport stage in the situation that two ships load and unload at the same time, with the shortest total transport path of trucks in the whole system as the objective function. Then the paper solves the mathematical model, that is to complete the trucks’ path optimization. Trucks’ path optimization problem can be seen as an extension of vehicle routing problem (VRP). So the Improved ant colony algorithm and a heuristic algorithm are used for solving the model.Analysis of the example showed that the proposed three-phase optimization model on container terminal operations and algorithm can improve equipment utilization and efficiency of terminal operation system, has some practical significance.