| The container terminal is an important part of a port enterprise and an important node of modern logistics. Container terminals play an irreplaceable role in promoting the economic development of our country. With the growing increase of international trade quality and the container freight volume, the competition among container terminals is becoming increasingly fierce. As to those important factors for shippers and carriers in choosing the optimal container terminal, except for wharf natural conditions, the more important factor is the comprehensive service ability and dock service quality. Only by constantly improving port throughput ability, improving the management level, optimizing the terminal dock production mode, container terminals will in an invincible position of the fierce competition in the future.As one of the most important transportation equipment in container terminals, yard trailers has the most flexible application, the largest scale and the most complicated working condition in the loading and unloading operation. whether the yard trailers can be scheduled and assigned reasonably and efficiently will directly affect the operation of other port facilities, the terminal handling efficiency, yard stocks utilization rate and operation cost of container terminals. Therefore, how to improve the operation efficiency of yard trailers and change the scheduling mode of yard trailers has already become an important problem in those studies on container terminals.In order to improve the operation efficiency and economic benefits of container terminals, reduce the operation cost of container terminals and the wasting of operation resources, increase the utilization of operation facilities and equipment in container terminals, this paper will study the scheduling optimization research on yard trailers based on the mix-cross operation mode of container terminals. In this mode, quay cranes realise the coorperation of container loading and unloading in one operation on berthed ships. And based on the different operation efficiency of yard cranes and quay cranes, the different operation progress of different berthed ships, yard trailers can dynamicly operate between quay cranes and yard cranes to realise the loaded operation both in loading and unloading process.Based on the mix-cross operation mode in container terminals and with the premise of specific berthing plan, this paper established the yard trailers scheduling optimization model with the objective function of minimizing the yard trailers routing. This problem is studied under two circumstances which is the import stock plan unknow and quay cranes handling sequence unknow. In order to reduce the complexity of the actual container terminal production scheduling, in the situation of unknow import stock plan, the optimal routing and number of yard trailers can be achieved by assigning the most reasonable import stock for those containers to be discharged. In order to comply with the actual production process of container terminals, in the unknown handling sequence of quay cranes, the optimal routing and number of yard trailers can be achieved by dealing with the reasonable operation sequence of quay cranes.The scheduling problem of yard trailers in container terminals is relatively complex, which involves many classic optimization problems, including TSP problem, VRP problem, the most short circuit problem and so on. Considering the NP completeness of this problem, this paper designed an genetic algorithm to solve the scheduling optimization model of yard trailers. Finally through the example experiments, the optimal routing and number of yard trailers based on the mix-cross operation mode in container terminals can be achieved, and so is the optimal handling sequence of quay cranes. It can be shown in the analysis results that the proposed model and algorithm in this paper can effectively reduce the yard trailers operation distance and improve the operation efficiency of container terminals. |
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