Abstract
As the “first service station” for ships in the whole port logistics system, the tugboat operation system is one of the most important systems in port logistics. This paper formulated the tugboat scheduling problem as a multiprocessor task scheduling problem (MTSP) after analyzing the characteristics of tugboat operation. The model considers factors of multianchorage bases, different operation modes, and three stages of operations (berthing/shifting‐berth/unberthing). The objective is to minimize the total operation times for all tugboats in a port. A hybrid simulated annealing‐based ant colony algorithm is proposed to solve the addressed problem. By the numerical experiments without the shifting‐berth operation, the effectiveness was verified, and the fact that more effective sailing may be possible if tugboats return to the anchorage base timely was pointed out; by the experiments with the shifting‐berth operation, one can see that the objective is most sensitive to the proportion of the shifting‐berth operation, influenced slightly by the tugboat deployment scheme, and not sensitive to the handling operation times.
Highlights
Container terminal is an important part in international logistics and plays a significant role in world trade
By the numerical experiments without the shifting-berth operation, the effectiveness was verified, and the fact that more effective sailing may be possible if tugboats return to the anchorage base timely was pointed out; by the experiments with the shifting-berth operation, one can see that the objective is most sensitive to the proportion of the shifting-berth operation, influenced slightly by the tugboat deployment scheme, and not sensitive to the handling operation times
We introduce the simulated annealing into the ant colony algorithm, which can guarantee the quality of the search and avoid the phenomenon of the local optima
Summary
Container terminal is an important part in international logistics and plays a significant role in world trade. The exact same tugboat can provide all the three types of service berthing, shifting berth, and unberthing , which means that the machine set for all the three stages is the same This is different from a typical MTSP in which the available machine set in each stage is not the same. Liu 4 established an tugboat scheduling model considering the minimum operation distance of the tugboats, and compared the performance of hybrid evolutionary strategy with the particle swarm optimization algorithm for solving the addressed problem. As we can see from the previous research, scholars have begun to use many approaches to solve the tugboat scheduling problem, including the genetic algorithm, ant colony optimization, and particle swarm optimization.
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