A Study On Optimization Of Synchronous Loading Operation Of Ouav Cranes And Straddle Carriers In The Container Terminal

With the continuous development of economic integration and trade globalization,container ports have achieved considerable development in the world as an important node of global supply chain and port logistics,and China's performance is particularly prominent.The operation efficiency of container ports is not only positively associated with the economic benefits and security stability of China's foreign trade,but also related to the transportation,storage,and handling of containers which are challenging.Therefore,this problem has considerable practical utilization and theoretical research value due to the complexity in its decision-making process and has become one of the research hotspots of scholars at home and abroad.As two main types of equipment at the apron of a port,quay cranes and straddle carriers play an increasingly important role in affecting the overall efficiency of container handling at ports.Based on the field research,this thesis focused on the multiple quay cranes and multiple straddle carriers synchronous scheduling problems with multiple lanes that need to be solved in the operation management of several major container ports in China.Firstly,a mixed integer programming model of synchronous scheduling problem is developed according to the field research and literature survey,which can be an approach of theoretical analysis.The model aims to minimize the completion time of the quay cranes and the waiting time of the straddle carriers with the consideration of flexible the sequence of the container handling.Several realistic constraints are considered,such as the operation of quay cranes is constrained by the position of straddle carriers,and the spreader with a container is not allowed move over a straddle carrier.Next,a dynamic greedy policy based two-layer hybrid genetic algorithm is developed to solve the problem.The upper layer algorithm solves the quay crane loading and unloading sequence,and the lower layer algorithm determines the decision sequence of the straddle carrier.In addition,a heuristic algorithm is designed based on greedy policy to dynamically adjust the scheduling of arranged containers and to select the optimal pair of lane and handling time for each straddle carrier and quay crane to obtain feasible solutions of high quality.Computational experiments are conduced to show the efficiency of the proposed algorithm.The comparison between the algorithm and CPLEX at small size problems showed that the algorithm can obtain the optimal solution in reasonable time horizon.For larger size problems,the algorithm can overcome CPLEX in terms of solution quality and computational time.This thesis also compared the algorithm with existing policy that has been implemented by some ports in the real world.The results also showed that the algorithm can obtain better solutions than the existing policy,which revealed the efficiency of the algorithm.This algorithm is expected to be a useful and practical approach of determining the optimal scheduling of quay cranes and straddle carriers to improve the performance of ports.