Research Of Collaborative Optimization Of China Railway Express's Operation Plan And Assembly Center

With the rapid increase in the number of China Railway Express and cities operate Chian Railway Express,the existing transportation organization model has been unable to adapt to the rapid development of Chian Railway Express.Therefore,it is urgent to design an economic and convenient transportation organization model.Most of the existing researches on China Railway Express's transportation organization are conducted from a qualitative perspective on the organization strategy.There are few quantitative studies on the transportation organization strategy of China Railway Express.In the related research,there are five shortcomings.First,considering single transportation organization model and single form of the train.Secondly,node function positioning is very fuzzy.Thirdly,the selection of the assembly center is not rigorous.Fourthly,the solution case is small.Fifthly,the relationship between cargos flow,containers flow and trains flow is ambiguous.Based on the problems of China Railway Express's transportation organization mode and the deficiencies of the existing research,the research steps in this paper are as follows:Firstly,this paper analyzes the OD characteristics of the cargo flow and the container flow of China Railway Express,afterwords,this paper sorts out the four types of trains:direct trains,ladders trains,transfer bases trains and transfer direct trains.Based on that,this paper sorts out four types of transporatation modes:"all direct" mode,"complete assembly" mode,"direct+assembly" mode,"direct+ladder direct+assembly" mode.In addition,this paper makes conversion of cargo flow,box flow and column flow in 4 modes Relationship analysis.Secondly,this paper uses the improved k-means semi-supervised clustering algorithm based on variable compression weights to cluster China-European network nodes.Based on the designed direct trains,ladders trains,transfer bases trains and transfer direct trains,the node differentiation function is designed for the nodes after clustering.Thirdly,this paper takes China Railway Express's Operation Plan and Assembly center into consideration,and establish a collaborative optimization model for China Railway Express's Operation Plan and the location of the assembly center.The optimized model is a large-scale mixed integer programming model,the improved genetic-simulated annealing hybrid algorithm was designed to solve the problem.Fourthly,this paper selects 42 nodes in the actual China-Europe transportation network for case analysis.The calculation results show that under the simulated OD data,based on the three operating evaluation costs of box operation,box transportation time and box logistics cost,the sorting is "Direct+Ladder Direct+Assembly","Direct+Aggregation Mode","All Direct" mode,and "Complete Assembly" mode.