Research On Multi-objective Model Optimization Of Railway Empty Cars Allocation

In recent years,with the rapid development of our country’s high-speed railways,the separate running of trains for passenger and freight has gradually covered the scope of the national railway network.The freight capacity of the existing lines has been strengthened,and the freight volume has increased significantly.At the same time,customers have put forward higher requirements for the quality of railway freight services.It is required that empty cars,as a means of transport for freight,timely delivery to empty car demand stations is the primary prerequisite for the guarantee of freight services.However,the allocation of empty cars is affected by many factors,and formulating an efficient and reasonable allocation plan for empty cars has always been an important topic of in-depth research by scholars at home and abroad.This paper focuses on the optimization model of empty cars allocation,draws on previous research results,combines qualitative analysis and quantitative calculation,and comprehensively uses related research methods in various disciplines such as operations research and optimization theory to construct a multi-objective model for empty cars allocation and solve the problem.This paper mainly focuses on the following aspects:First of all,the principles,methods and core of empty cars allocation are expounded,combined with the principles and content of the comprehensive allocation of empty-heavy cars,and the data sources of transportation resources and empty cars resources are explained.The role and significance of car types substitution and timeliness in the comprehensive allocation of empty-heavy cars are analyzed,and the process of empty cars allocation is summarized,which lays a theoretical foundation for the study of the multi-objective model of empty cars allocation.Secondly,based on analyzing the transportation problem model of empty cars allocation,considering the empty cars allocation model of the multiple car types,and the empty cars allocation model of the comprehensive allocation of empty-heavy cars,a multi-objective model of empty cars allocation is constructed.By comprehensively considering various factors of the problem of empty cars allocation,the running cost of empty cars,the cost of substitute car types and the shipping income are included into the objective function of maximum enterprise benefit,and the departure time of heavy cars is used as a quantitative index to construct a fuzzy membership function of customer satisfaction,and finally the maximum objective function of customer satisfaction is established,the constraints include empty cars supply constraints,constraints of maximum freight volume of the supply station,constraints of remaining loading operation capacity of the supply station,empty cars demand constraints,constraints of remaining unloading capacity of the demand station,and constraints of freight volume of the demand station.Based on the multi-objective model of empty cars allocation,the constraint of path passing ability is added.In addition,the fuzzy membership function of customer satisfaction in the existing literatures is mostly represented by trapezoidal fuzzy numbers,but this paper uses a curve composed of trigonometric functions to represent it.The curve can well describe the phenomenon of poor evaluation near the marginal point,and is more in line with the psychological changes of customers in real life.Finally,the standardized weighted sum method is introduced,and a linear weighted combination method based on the comprehensive satisfaction of empty cars allocation is proposed.Combined with the advantages of LINGO in solving multi-objective programming problems.By taking grain,wood,and container transportation in a certain area as an example,applying the multi-objective model of empty cars allocation established in this paper with the goal of maximizing enterprise benefit and maximizing customer satisfaction to solve the example.The calculation results show that the former(linear weighted combination method based on the comprehensive satisfaction of empty cars allocation)has higher enterprise benefits and comprehensive satisfaction of empty car allocation than the latter(standardized weighted sum method),and the former has a shorter calculation time.To sum up,the scheme obtained by the linear weighted combination method based on the comprehensive satisfaction of empty cars allocation is better.Therefore,the linear weighted combination method based on the comprehensive satisfaction of empty cars allocation is used to solve the multi-objective model of empty cars allocation considering the path capacity.The analysis and comparison of the solution results of the two models shows that it is necessary to comprehensively consider the route passing capacity,car types substitution and the comprehensive allocation of empty-heavy cars in the process of empty cars allocation.Moreover,the multi-objective model of empty cars allocation considering enterprise benefit and customer satisfaction has been effectively improved compared with the empty cars allocation model that only considers customer satisfaction,its corporate efficiency and overall satisfaction with empty cars allocation have been effectively improved.