Research On Optimization Of Capacity Coordination For Technical Station And Line Based On Car Flow Assignment In Railway Network

With the implementation of Chinese railway freight incremental action plan,the structure and scale of railway freight demand have changed.On the one hand,the transportation volume of bulk cargoes has increased year by year due to the guidance of road-to-rail transfer policy.On the other hand,with the opening of 10,000-ton trains on Tanghu Line and the opening of Haoji Railway,the capacity of railway channels has also been strengthened.Thus,the problem of capacity coordination of stations and lines has become seriously.Undoubtedly,this will give the rail transportation greater challenges.Studying the capacity coordination of stations and lines can alleviate the mismatch between them and help make more rational use of existing transport resources.The nodeline load-balanced is the desired state of the capacity coordination in this thesis,and this goal is achieved by adjusting the car flow assignment in railway network with the optimization model,in order to improve the overall transportation resource utilization level of the network.The main contents of this thesis include the following parts:(1)The theoretical basis of the capacity coordination of stations and lines in railway network is studied.First,starting with the definitions of node-line capability and the principles of coordination,the connotation of capacity coordination of stations and lines in railway network is analyzed.Furthermore,based on the connection relationship between station and line,a road network coordination measurement method considering the difference between the capacity of technical stations and lines is proposed.Then,the characteristics and application situation of Node-Arc model and Arc-Route model are summarized.Combined with the feature of the model,the candidate set of car adaptated stations is introduced and its application value is analyzed.(2)The capacity coordination of stations and lines in railway network based on car flow assignment is studied.With analyzing the problem,an improved Node-Arc model of car flow assignment is constructed,which takes the minimum transportation total costs and rationality of capacity coordination of stations and lines as the objective functions,and takes station adaptating capacity and line passing capacity as constraints.And the model is linearization processed.An example is designed,the validity of the model is verified by comparing the capacity coordination of stations and lines under the before and after optimized car flow assignment schemes.(3)The algorithm for solving the optimization model of car flow assignment is designed.First,the model and the algorithm are analyzed.Then,with the characteristics of the model and the basic ideas of Micro-evolution algorithm,a car flow assignment optimization algorithm is designed.The algorithm can efficiently solve the model in an acceptable time.(4)An actual railway network is studied.Based on the simplified Chinese railway network,a simplified railway network is constructed with 30 technical stations.The capacity coordination of stations and lines in railway network under the before and after optimized car flow assignment schemes are compared and analyzed,and give corresponding suggestions to the capacity bottlenecks in the case network.Finally,the optimization effect of the model is analyzed in terms of the total coordination degree of the network and the average transportation detour rate.