| The Electrical Multiple Units(EMU)serves as a kind of railway passenger transportation resources,and it is an important component of the high-speed railway system.With the rapid development of high-speed railway in recent years,the number of EMUs has been increasing day by day.So how to enhance the management problem of EMU assignment and maintenance operation is paid more and more attention by the EMU management department,and this work is directly reflected in the assignment plan and the maintenance plan of EMU respectively.However,the EMU assignment plan and the EMU maintenance plan are correlative each other,and they influence each other as well.Therefore,it is necessary to combine the EMU assignment plan and the EMU maintenance plan,and then they are optimized together at the same time,which is helpful to improve the quality of the EMU assignment and maintenance plan.The comprehensive optimization of this problem is not only helpful to improve the utilization efficiency of EMU,but also be helpful to reduce the operation cost and the maintenance cost of EMU.By referring to the practical management of EMU assignment and maintenance and aiming at the comprehensive optimization of EMU assignment and maintenance planning,the main research contents of this dissertation are as follows:(1)By referring to the practical management of EMU assignment and maintenance,the basic service of EMU assignment and maintenance is analyzed from a few aspects,such as the general development situation of high-speed railway,the maintenance system of EMU,the process and its interrelation of EMU assignment and maintenance planning.The analysis lays a foundation to study the comprehensive optimization method for EMU assignment and maintenance planning.(2)Based on the trains included in the train diagram,the comprehensive optimization method for EMU assignment and maintenance planning is studied by adopting the space-time network theory.Firstly,considering the status transition of EMU and the status includes being in service,being in maintenance and being in standby,a serial-typed time-space network is constructed from three dimensions which are space,time and status.Each route of the time-space network represents the all operation processes of EMU during the planning period,and the EMU assignment and maintenance plan is reflected in the combination scheme of routes for all the EMUs.And then,after generating the set of routes for each EMU,a mathematical model for optimizing the combination scheme of routes is proposed by referring to the arc-path model.What's more,the strategy of generating the route set and the heuristic algorithm of solving the optimization model are designed as well.At last,through a case study,a problem is discovered that if the research object considered in this problem is too small,the problem will become too difficult to be solved effectively.So the problem is divided into two sub-problems and each of them is to be solved respectively,one is to optimize the train circulation plan based on the train diagram,and the other is to optimize the EMU assignment and maintenance plan on the basis of train circulation plan.(3)For the problem of optimizing the train circulation plan based on the trains included in the train diagram,at first the train circulation is expressed as a closed loop circuit by considering the connection relations among trains and the maintenance period of routine maintenance program,and the closed loop circuit consists of the connection of trains and the maintenance operation.And then,let all the train circulations be connected together through the maintenance operation,and only one closed loop circuit can be gotten during the train connection network.On this base,a 0-1 integer programming model for optimizing the train circulation plan is proposed on the basis of network optimization theory,and this model aims at minimizing the total connection time of trains and maximizing the travel mileage of each train circulation.In order to solve the model,by considering the serial number of trains and their location number in the connection network,a heuristic algorithm based on the particle swarm optimization algorithm is designed,as well as a case study.(4)On the premise of the given train circulation,let "minute" as the minimal unit of time and take the problem of EMU assignment and maintenance as a special travelling salesman problem on the basis of a consecutive connection for the train circulation.Then,set a virtual start train circulation and a virtual end train circulation for each EMU,and a connection network of train circulations is constructed and it contains the routine maintenance and special maintenance of EMU.Based on this,for the problem of EMU assignment and maintenance with single EMU type,single EMU depot and single marshalling mode,a 0-1 integer programming model for EMU assignment and maintenance planning synthetically is proposed.This model aims at minimizing the total connection time of train circulations and minimizing the waste of the available mileage for EMU when maintenance occurs,and the constraints of undertaking train circulation and maintenance cycle are mainly contained in this model.Besides,by referring to the set of train circulation number,a heuristic algorithm based on the particle swarm optimization algorithm and a case study are designed.(5)For the problem of EMU assignment and maintenance planning based on train circulation plan,further consider the practical situation that EMU undertakes the train circulation and let "day" as the minimal unit of time for planning,and the problem of EMU assignment and maintenance is taken as a special assignment problem approximately from a discrete perspective.According to the process of EMU assignment and maintenance,a set of decision variable are designed and they are called major decision variable,auxiliary decision variable and status decision variable respectively,and an another 0-1 integer programming model for EMU assignment and maintenance planning synthetically is proposed.Apart from the constraints of undertaking train circulation and maintenance cycle,the maintenance capacity of EMU depot is also be taken into consider,and this model aims at minimizing the number of EMUs in service and minimizing the waste of the available mileage for EMU when maintenance occurs.In order to solve the model,a heuristic algorithm based on the binary and discrete-typed particle swarm optimization algorithm.At last,a case study is designed on condition that the boundary of the problem is unified,and the two different optimization method based on the given train circulation plan are analyzed through this case study.Through the research on the optimization model and solution algorithm,an integrated optimization method for EMU assignment and maintenance planning is formed from different perspectives,which can provide an auxiliary reference base for planning the EMU assignment and maintenance in the practical transportation production process. |
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