Study On Optimization Theory And Method Of The Wagon's Takeout And Delivery Scheduling In Railway Station

The takeout and delivery shunting is important for the freight station and the technical station with a lot of cargo handling operations. The wagon's takeout and delivery scheduling system in railway freight station (WTDSS) is a subsystem of railway station scheduling system, and its operation efficiency has a close bearing on the on-schedule rate of departure trains, wagon turnround time and many other transportation production indexes. Those problems from the WTDSS are collectively referred to as the wagon's delivery and takeout problem (WTDP).This dissertation dealt with the optimization theory and method of the WTDSS. It systematically analysized elements, structure, environment and charactoristies of the WTDSS and deeply studied modeling, model implementation, optimization algorithm and heuristic methods of the WTDP, and put forward a novel concept that is two-dimensional combinatorial optimization problem. The research work in the dissertation mainly includes the following:1. The WTDSS was synthetically analysized. Specifically, the objects of wagons' takeout-and-delivery shunting, the loading-unloading locations and their layout forms, all kinds of takeout-and-delivery operations and their component elements, the operation organization modes, the functional factors of the WTDSS were analysized comprehensively, the relevent concepts were clearly defined, and the environment and characteristcs of the WTDSS were systematically discussed, which lay the groundwork for further research on the WTDP.2. The WTDP whose loading-unloading locations show radial layout (R-WTDP) was studied. Under the assumption that the locomotive haulage capacity and the wagon acceptance capacity of each loading-unloading location are both unlimited, the ideal models for the non-through and the unfixed form wagon flow were respectively established based on the fact that the sequence, moment and batch number problems of takeout-and-delivery operations during a period of time are a whole. According to features of the built models, expression method of the solution was designed, and modular implementation method for the models was proposed to construct solution and to calculate the value of solution. The scheduling schemes obtained by the models and their implemation method have various adapting operation organization modes, and therefore overcome the shortcomings caused by using the fixed organization modes.3. Based on the characteristics of WTDP whose loading-unloading locations show tree-shape layout (T-WTDP), two models were respectively built for the non-through and the unfixed form wagon flow in the case of several trains successively arrived in the railway station, and the solution expression and the modular implementation method for the models were successively presented. Through the models and their implementation method, the reasonable operation schemes can be found which not only include the reasonable sequences, moment and batch number of takeout-and-delivery operations in planning stage but also have the adpting operation organization modes.4. Based on the reaserch results about the R-WTDP and the T-WTDP, the generic model (G-WTDP) was built for the sequence, moment and batch number problems of takeout-and-delivery operations during a period of time, which applys to different loading-unloading location layouts, all kinds of arrival or departure wagon flows. And then the WTDP is clearly defined as a kind of combinatorial problem with two optimization dimensions by analysis on its two-dimensional combinatorial optimization property. Aiming at the high computational cost of solving the WTDP, a set of methods used to generate the complete solution was presented by abstracting and standardizing some objective constraints of the WTDP and principles arising from practical experience. Through the proposed methods, the search space of the WTDP can be reduced from n!×2n-1 to n!, and therefore improve the efficiency of solving problem. The therotical basis for the determination procedure of batch scheme was dicussed from the set theory point of view. Three benchmark examples which are respectively for R-WTDP, T-WTDP and G-WTDP were designed, and their best known solutions were given.5. To improve algorithm's adaptability to different situations, a hybrid algorithm with adapting parameters was proposed. It treats ant colony optimization system (ACO) and genetic algorithm (GA) as its two parallel strategies, and it uses the cloud association rules, grey prediction and feedback from its iterative process to control adaptively relevant parameters, which can effectively reduce the reliance on initial setting of parameters. In view of WTDP characteristics, the time-expectation heuristic information and a novel mutate operator are presented. The former is used as visibility in state transition probability formula of node selection to improve the algorithm convergence efficiency. The later is used to transform a kind of infeasible solution which cannot meet the time-domain constraint, which makes the obtained solution be or be more close to feasible one and therefore improve time efficiency for solving the WTDP.This dissertation is on the basis of the combinatorial mathematics theory, the set theory, some transportation production experience, and so forth, is under the guidance of theory and methodology of system science, uses computer technology as a tool, adopts many methods such as integrating qualitative requirements with quantitative constraints, combining objective constraints with empirical principles and harmonizing theoretical reaserch with example analysis, has established the mathematical models of the WTDP, has proposed the model's modular implementation method, has presented the heuristics that is helpful in increasing algorithm's capability to search optimal solution, has verified research conclusions by analysis on the simulation examples, and has finally formed a relatively intact theory system. The optimization theory and method of the WTDSS is an essential part of the railway station scheduling system theory, so its research results can provide the further theory basis and technical support for realizing the intelligent railway station scheduling system, contribute to improvement in scheduling decision level and transportation efficiency, help to raise comprehensive automatic performance of the railway station scheduling system, and then produce enormous economic and social benefit.