Research On The Optimization Of Railway Empty Containers Repositioning Under The "Real-freight System"

In recent years,China has made some progress in the adjustment of its industrial structure,and its economic growth rate has moderately slowed down.Accompanied by the obvious changes in the structure of demand for freight transport,the demand for small batch goods has grown rapidly,and the transportation market has become increasingly competitive.In order to enhance its own market competitiveness,since 2013,railway freight has implemented the reform of “real-freight system” and has successively introduced optimization adjustments for container transportation business.Both reforms are for railway freight transport,especially container transport,have played an important role in adapting to the new situation of the current transportation market.The implementation of the "real-freight system" has not only improved the timeliness of railway freight transport,but also enabled customers to obtain a better service experience because they can independently book empty containers and select single or full logistics services.After further research and reflection of relevant literature on the empty container transport problem,combined with the new requirements for freight transport reform,we set up an empty container transport model that adapts to the current situation in the freight market.The main research contents of this paper are as follows:(1)In-depth study of the development status of empty containers and other issues,and focused on the impact of freight reform on the empty container transport.Under the current situation,we need to focus on the randomized demand for empty containers.It also points out that the purpose of studying the empty container transport problem is to make it adapt to the current railway requirements for improving the quality of freight services.(2)For the random empty containers demand,the chance constraint plan is introduced,and the empty container demand of the demand station is regarded as a random variable.At the same time,in response to the requirements of the freight reform to improve the quality of railway freight services,time windows are introduced to restrict the time for transporting empty containers to the station and ensure the timely transportation of customer goods;And uses the leasing strategy as a complementary strategy for empty containers to meet the customer's maximum packing requirements.(3)The two major objectives of the model are clarified,that is,the minimum transfer costs for empty containers and the minimum turnaround times for empty containers transfer.Transfer costs include the cost of empty containers transport services,lease empty containers costs,and the time costs incurred due to not arriving in time;The turnaround time includes the time of on-the-way transportation and on-site operation time,and the time of on-site time is the analysis and calculation of the assembly time.Based on the analysis of theabove two objective functions,a dual-objective empty containers transfer optimization model with random chance constraints is established.The model considers the limitation of the empty container transport capacity.(4)The algorithm of the model is designed and the hybrid intelligent algorithm is used to solve the dual-objective model with random chance constraints.The algorithm combines random simulations,neural networks,and NSGA-II.The advantage of the algorithm lies in the combination of random simulations and neural networks,so that random constraints do not have to be transformed into a definitive expression.NSGA-II is also called multi-objective genetic algorithm.It uses non-dominated stratification and crowded distance sorting to select offspring individuals,which makes it better in solving the dual-objective model.(5)According to the model,the corresponding examples are given.Using MATLAB software to solve the examples and analyze the calculation results,the feasibility of the model is verified.