In order to reasonably schedule tugboat operation, effectively improve tugboat utilization factor and reduce the waiting time of vessels, the multiprocessor tasks scheduling theory was applied to analyze the tugboat operation scheduling problem according to the characteristics of the tugboat operation. Considering the minimum operation distance of the tugboats, an optimization model was built to minimize the maximum makespan of all ships. The evolutionary strategy algorithm was applied to optimize the tugboat operation scheduling, and an encoding and coding method based on the roulette probability assignment was proposed. The recombination operator based on three-point crossover and the mutation operator based on the gene cross-over in the individual were designed. The results of a case study show that the optimization results achieved by the evolutionary strategy algorithm is obviously better than those by the simulation and the particle swarm optimization algorithm. When using real encoding, the minimum of the maximum makespan obtained by the proposed optimization method is 356 min, which is less than the simulation results by 117 min. When using integer encoding, the minimum of the maximum makespan is 369 min, less than the simulation results by 104 min. Thisverifies the effectiveness of the minimum operation distance rule for tugboats.%为了合理调度拖轮作业,有效提高拖轮的利用率,减少船舶等待时间,针对拖轮作业特点,用多处理器任务调度理论分析了拖轮作业调度问题.在考虑拖轮最短距离作业的前提下,以最小化最大完工时间为优化目标建立了拖轮作业调度模型.采用演化策略算法对拖轮作业调度问题进行优化,提出了一种基于轮盘赌概率分配的编、解码方法,并设计了三点交叉互换的重组算子和个体基因交叉互换的变异算子.算例结果表明:用演化策略算法的优化结果优于仿真结果和粒子群算法的计算结果.采用实数编码时,通过优化算法得到的最大完工时间最小值为356 min,比仿真结果减少了117 min；而采用整数编码时,最大完工时间最小值为369 min,比仿真结果减少了104 min.验证了最短距离作业原则的有效性.
展开▼
