Study On Improvement Of Modles For Railway Empty Wagons Distribution Coordinate-optimization

Empty wagon distribution as the important elements of railway transportation technical program has an important influence on the distribution of railway vehicles,quality of service,balance of transportation and so on.The raise of "real-freight system" has had an enormous influence on existing transportation organization.And it provides an important opportunity of optimization distribution for railway empty wagon.Since so far the research of railway empty wagon distribution has encountered an obstacle and formed its own theoretical system,this paper focused on the nature of empty wagon distribution to improve the model,enrich the theory of wagon flow organization and the adjustment of traffic,simplify the model structure,and raise a more convenient solving method.This paper based on learning from the former research both in home and overseas.It applied correlative theories about optimization theory and railway transportation organization to make improvement on models for railway empty wagons distribution coordinate-optimization.The main contents are as follows:(1)Through the sorting and classification of domestic and foreign models of railway empty wagons distribution,combining with the core,principles and methods for empty wagons distribution,comparing with the merits and disadvantages of empty wagon distribution models,it ensured the object to be improved was the models of railway empty wagons distribution coordinate-optimization.(2)This paper described the models of empty wagons distribution coordinate-optimization and the improvement for it in detail.And it analysed the deficiency and merit of the improvement.Starting with why the models are complicated,it sorted out the method of the improvement for general models.Then it ensured the improved target of this paper was constraint conditions of the models.(3)It aimed at analysing the constraint conditions of the models to draw a conclusion that the constraint of no-convection for node repeated with prerequisite.And it was incative for the optimal results.So it could be deleted directly.According to the actual road network,the network of the models was normally overcapacity.So considered about the capacity constraint was not necessary.It analysed the relationship between the constraints and found that the constraint of no-convection for section could be at odds with the constraint of common route,so both of them should be improved together.(4)It supplied the idea for improving the constraint of common route and no-convection for section that proving the optimum solution of models without the constraint still satisfied the constraint.It began with analysing the simple situation of section convection.Then it generalized the general form about section convection and proved the improvement about the two constraints.Finally,it improved the model into a typical relation model about arc and route.(5)The improved model about arc and route continued being simplified.Finally the models for railway empty wagons distribution coordinate-optimization under the condition of excess capacity was simplified into a balanced transportation problem taking the cost of the shortest path as the price coefficient.(6)Taking the simplified network of Nanning railway as an example to illustrated the improved model.Thus it indicated the effectiveness and advisable of model improvement.