Research Of Railway Stowage Problem Of Steel Products Based On Differential Evolution Algorithm

There are three transporting ways of steel productions in iron and steel enterprises,i.e.,motor transportation,ship transportation and railway transportation.Among those ways of transportations,the railway transportation has the advantages of higher security and less transportation cost compared with the other two transportations.Therefore,the railway transportation occupies a higher proportion in the product logistics of the steel enterprise.In this thesis,the railway stowage problem of iron and steel products is researched systematically,based on the background of steel productions transportation of iron and steel enterprises.Railway stowage is the middle part of connecting iron and steel enterprise products and the market,and the guarantee for reasonably assigning the products to the wagons.It can effectively decrease the loading time and the hidden dangers in transportation and reduce inventory by developing a good stowage scheme,which plays an important role in improving enterprise competition.The stowage problem of steel products in iron and steel enterprises has been studied deeply in this thesis.The main work includes:(1)Railway stowage problem of steel products in iron and steel enterprises is to determine the number and type of wagons for target coils,and to determine the loading position of each coil in the wagons according to the weight,width and destination information of the coil in the stowage plan.Taking into account of the placement of the steel coils in the wagon,destinations,the weight balance of wagons after loading and other constraints,the objective of this problem is to minimize the idle loading capacity of wagons,the weight difference between front and back and the weight difference between right and left of wagons.A linear integer programming model is established to describe the problem.Besides,the mathematic model can be optimally solved by CPLEX in small cases,which verify the correctness and validity of the model simultaneously.(2)Due to the complex constraints and the difficulty in solving the problem with large-scale,a heuristic algorithm and a modified differential evolution(DE)algorithm are developed based on the characteristics of the problem.In order to improve the performance of DE,firstly,an improved strategy based on parameter self-adaptation and new mutation strategy are proposed.Then,to obtain the best performance for solving the problem,an orthogonal experiment is designed to choose the most appropriate control parameters and mutation strategy in DE.Finally,actual data and random data test results show that the improved DE proposed in this thesis performs better than the classic differential evolution algorithm both in the CPU time and the solution quality.Besides,the modifying effect of the improved differential evolution algorithm,whose parameter combination is determined by the orthogonal experiment method,is more significant.(3)Considering the actual needs in practical stowage,a railway auto-stowage decision support system is designed and developed based on the established mathematical model and the proposed differential evolution algorithm.From the utilization of the system,it shows that the decision support system can effectively reduce transport cost,improve work efficiency,reduce the time to formulate the stowage program,and improve the efficiency of stowage.