Research On Integrated Optimization Of EMU Assignment And Daily Maintenance Plan For High-speed Railway

With the rapid increase of high-speed railway network scale in China,the quantity of EMUs and EMU depots have been rising and utilization scope of EMU becomes wider and wider,which add difficulties to the coordinated management between EMU utilization and maintenance.As the direct reflect of EMU's daily management level,the EMU assignment plan and the EMU daily maintenance plan are correlative and interactional with each other.Therefore,it is necessary to integrate the EMU assignment plan and the EMU daily maintenance plan to achieve integrated optimization.By referring to practical characteristics of EMU utilization and daily maintenance,and based on experience and deficiency of existing relevant theory research,the dissertation makes extensive optimization research on integrated making of the EMU assignment plan and the EMU daily maintenance plan.The main research contents of the dissertation are as follows:(1)Elaborate and analyze the EMU utilization and maintenance problem of high-speed railway in China.Firstly,the dissertation introduces and analyzes the current circumstances of EMU utilization and maintenance from many aspects,such as EMU operation mode,maintenance criteria of EMU,EMU maintenance mode,the process of EMU utilization and maintenance and so on.Next,it makes analysis of the making relationship between the EMU assignment plan and the EMU daily maintenance plan,the meaning,objectives and influence factors of the two plans in detail.Combining that with the high-speed railway network,the research object of the dissertation is proposed,namely integrated making of the EMU assignment plan and the EMU daily maintenance plan,and the framework of integrated making of the two plans is also displayed.Lastly,based on the practical situation of EMU's daily maintenance and considering accurate maintenance time of different maintenance tasks,the dissertation makes in-depth research on both division of maintenance time interval and optimization of maintenance capacity,which lays a foundation on the subsequent integration modelling.(2)Analyze and summarize the characteristics and disadvantages of different existing modelling methods on integrated making of the EMU assignment plan and the EMU daily maintenance plan,and also propose a new optimization one.At first,the dissertation constructs an optimization connection network and feasible utilization paths of EMU are generated on the basis of the network.Next,selecting the path as decision variable and considering some constraints including routing section covering,maintenance capacity limit,it proposes a multi-commodity integration model belonging to the 0-1 linear integer programming,which aims at minimizing the number of EMUs in use and minimizing the waste of the total available mileages for EMUs corresponding to all maintenance items.(3)Based on the feature of the model,the dissertation proposes the branch-and-price algorithm which embeds the column generation algorithm into branch-and-bound framework to solve the model.Also,it designs the framework of branch-and-price algorithm and its whole solving process.(4)Take some EMU depot in China as an example to make case analysis and validate the proposed model and algorithm.Firstly,a small-scale example with period of four days which only considers part of maintenance items is solved by CPLEX and the proposed algorithm respectively,and then the dissertation makes comparisons of the corresponding solutions.The results show that the solution of the algorithm is optimal and of high quality,and its solving time is shorter than CPLEX's.Next,the algorithm is used to solve a large-scale example with period of a week which cannot be solved by CPLEX on the consideration of all maintenance items.The result indicates that the efficiency of the algorithm is still acceptably high,which thus demonstrates the feasibility and applicability of the dissertation's model and algorithm.