Optimization model of number of scheduled freight train formation cars
The determination of the number of formation cars is an important part of making a scheduled freight train plan, and it also has a large influence on the benefits of railway freight transportation. First, the influences that affect the number of formation cars are analyzed. Secondly, taking the maximum freight transport benefits as an objective, and comprehensively considering the primary factors that include service frequency of freight trains, section traction weight, effective length of arrival-departure tracks, and so on, this paper establishes the optimization model of the number of scheduled freight train formation cars. Finally, the solving method for the model is presented, and a case is given to show the solution process. It provides a reference for decision-makers of railway freight transportation.
The Programming of Freight Train Departure Timetable in the Mode of Accumulation with Fixed Time in Marshalling Station
Under the mode of freight trains accumulation with fixed time in marshalling station,it is a periodic event scheduling problem to end car group accumulation and to schedule different trains.According to the theory of Periodic Event Scheduling Problem(PESP),fully considering station operation capability and line carrying capability constraints,departing time of each train and periodic constraints between them are illustrated by periodic constraint graph.Based on the actual working requirements,the model of fixed-time-departure timetable of freight trains is established with benefiting locomotive operating and distributing departing times as evenly as possible as the objective functions.The model genetic algorithm is designed and solved by selecting proper spanning tree of periodic constraint graph and according to the sufficient and necessary condition of PESP.Taking the car flow in Beijing-Guangzhou direction in Fengtai West Marshalling Station as an example,the solution is obtained by the designed genetic algorithm.Calculation result demonstrates that it is probable to get a fixedtime-departure timetable of trains by selecting proper spanning tree to construct fundamental circle basis to help reduce the complexity of solving the model.The sufficient and necessary condition is added to get the feasible solution,which can efficiently save the time of solving the model to get freight train departure timetable at fixed time,the average accumulation hour and the average formation number of departure trains.
Research on velocity distribution in semi-dry flue gas desulfurization tower
As an accurate high-quality instantaneous measurement technology, particle image velocimetry (PIV in acronym) has applied widely in single-phase flow and multiphase flow. The velocity distribution in semi-dry FGD tower directly influences gas-solid mix and contact situation. In base of the tower, gas-solid two-phase flow field is more complex, and has the quite tremendous influence to the overall system desulphurization efficiency. This paper utilized PIV to study velocity distribution in Semi-dry flue gas desulfurization tower and obtained velocity distribution.