Research On Co-optimization Of Routes And Modes In Multimodal Transportation Network

With the rapid development of China's social economy,the total volume of freight is increasing.The single mode of transportation has low operating efficiency and high comprehensive cost,so that it is difficult to satisfy the rapid development of the logistics industry.As an advanced form of transportation organization,multimodal transportation can effectively improve the level of transportation management and maximize the economic performance by integrating advantages of multiple transportation modes.The perfect construction of multimodal transportation is inseparable from scientific and rational transportation planning.Therefore,based on the perspective of system optimization,the problem of co-optimization of routes and modes in multimodal transportation network is studied in this thesis.Most of the traditional multimodal transportation optimization problem is based on the assumption that the cargo flow cannot be split,that is,there is one transportation route between the origin and destination provided to the cargo to complete the whole transportation.However,there are usually multiple routes to choose between the origin and the destination in actual transportation.Moreover,the cargo flow could be splitted and the transportation mode could be transformed in transfer nodes.Due to the influence of uncertainty,the transportation capacity and transportation time may change,which make the plan cannot be implemented.And it is very necessary to split the cargo flow to improve the transportation efficiency.Therefore,it is of great practical significance for this thesis to concentrate on the problem of co-optimization of routes and modes of splitting goods in multimodal transportation network.The research contents of this thesis are as follows:(1)Research on co-optimization of routes and modes in multimodal transportation network under certainty.From the perspective of multimodal transportation network system,the objectives and influencing factors of multimodal transportation network optimization are analyzed in this work.Considering the limitation of transportation capacity,a mixed integer programming model with time constraints for minimizing total transportation cost is formulated.The improved simulated annealing algorithm is proposed to solve the mathematical model.Finally,the validity of the model and algorithm is verified by numerical examples.(2)Research on co-optimization of routes and modes in multimodal transportation network under uncertainty.Considering the actual transportation environment,the transportation under certainty is only a special case under ideal conditions.Therefore,according to the uncertainty of some parameters(transportation capacity,transportation time,etc.)in the research problem,they are assumed as random parameters.A co-optimization model of multimodal transportation under uncertainty is formulated.And the improved simulated annealing is proposed to solve the problem correspondingly.The validity of the model and algorithm is verified by solving the case.