Integrating Models And Methods For Scheduling Of Loading/Unloading Operations In Container Terminals

With the rapid increase of container terminal output in China, the operation scheduling becomes more and more complex. Thus scheduling models and algorithms are needed to support the operation practice. Issues related to container terminal operations have gained attention and have been extensively studied recently due to the increased importance of marine transport systems. However, how to tackle the complex constraints and interrelation; how to improve the computation efficiency; how to realize coordination of different sub-process; and how to integrate different scheduling methods and techniques, are the problems that have not been solved well.Considering the problems in existing studies, we will study the operation scheduling problem from two aspects. The first aspect is model integration; we improve the coordination of different sub-process and realize the integration of loading and unloading operations by integrating scheduling model, and thus improve the operation efficiency of container terminals. The second aspect is method integration; by the integration of optimization algorithm, simulation technique, and reinforcement learning, the description capability to complex system can be enhanced, and also the model solution efficiency can be improved.Firstly, from the aspect of whole operation process, we consider two sub-decisions in one model. An optimization model considering storage location and yard trailer scheduling is developed, and a two-phase tabu search algorithm is designed to solve the model. Based on this, an integrating scheduling model is developed to optimize the operation sequence of quay cranes, yard trailers and yard cranes simultaneously. And a hybrid algorithm is designed to solve the model.Secondly, a "multi-crane oriented" scheduling model to coordinate the operation of loading ship and unloading ship is developed. By this method, the yard trailers can be shared by different quay cranes. Therefore, empty drive of yard trailers can be decreased and the utilization ratio of yard trailers can be improved. Meanwhile, a two-phase tabu search algorithm was designed to solve the model.Thirdly, we study the problem that quay cranes perform loading and unloading operations simultaneously in the same ship-bay, namely quay crane dual cycling scheduling problem. Two models for quay crane dual cycling scheduling problem are developed, namely scheduling model supposing the loading plans are given; and scheduling model considering optimization of loading plans. To solve the models, a heuristic method, called bi-level genetic algorithms is designed.Fourthly, integrating the intelligent decision mechanism of optimization algorithm and evaluation function of simulation model, a simulation optimization method for operation scheduling in container terminals is proposed. To improve the computation efficiency, a hybrid optimization algorithm based on genetic algorithm and neutral network is designed. Meanwhile, simulation optimization is used to optimize the operation sequence of different equipments in loading and unloading process, the quay crane sequence and loading plan of outbound containers in quay crane dual cycling.Lastly, reinforcement learning is used to operation scheduling in container terminals, and also it is integrated with simulation technique. In this method, simulation model is used to construct the system environment, and optimal scheduling scheme is obtained by the interaction of Q-learning algorithm and simulation environment.