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.
Economical Efficiency Analysis on the Train Departure Strategy in Technical Station
The paper establishes two kinds of economical efficiency analysis models with fixed point and fixed consist about train departure mode.By analyzing the adaptability of fixed point and fixed consist under conditions of the decreased number of cars in fixed point,we can get the following conclusions:1.The lower burden area is the davantage part of fixed point mode.The heavier hump burden(0 8)of technical station goes against fixed point mode.Whereas,the lower hump burden is more strict with the adaptability of fixed point departure.In China,fixed consist departure mode is adopted over a long period of time;it has considerably important relationship with the lack of technical station ability.2.The fixed point mode is fit for the direction of small flow of arrived vehicles.In the case of small flow of arrived vehicles,we can consider to run the fixed point departure train on the basis of station practical situation.On the contrary,for large car flow direction,the fixed consist train is better.3.Fixed point mode has even better adaptability for short distance arrival direction.That tells us:if the distance between departure station and destination is a little shorter(shown by the less running time),according to flow and burden,run the fixed point train can be considered.Of course,the calculated data is not absolute because the model is simplified in some aspects.In the model,only internal cost of railway is considered.In fact,under the fixed point mode,it can acquire more practical efficiency to quicken freight car turn round,to shorten freight delivery time,to better punctuality and promote competition ability of transportation service.
Optimal Fixed-Time Vehicular Control for Multi-Junction Nodes Using Mathematical Programming
Abstract Multi-junction nodes are first defined as spatially narrow areas with several junctions very close each other and are then more deeply analysed and characterized. The problem of designing optimal fixed-time signal plans for them is formulated and discussed, and its peculiarities with respect to the area control problems are pointed out. A linear model with continuous and binary variables is set up expressing the requirements any signal plan should meet. It may produce a mathematical programming problem by introducing any suitable objective function. Finally, some methods are proposed to reduce the computational requirements to deal with such a model by curtailing the number of the binary variables and of their value combinations to be explicity considered.