The Study On The Method Of Road Freight Transportation When Demand Is Stochastic

Modern logistics is generally acknowledged as the third profit resource besides reducing the commodity consumption and enhancing labor productivity. It is also regarded as an important way in decreasing the operation cost and raising competitiveness for enterprise. Thus there are many countries paying more and more attention on it, and it steps into a rapid progress development. As an important link of operating logistics system, distribution is unreplaceable. With the development of economic and sharp competition of market, customer's requests for freight transportation on time and quantity get stronger and stronger. So how to deal with the supplies at the right moment and the right amount in satisfies the market demand is putting a new challenge to the distribution's scientific and rational and also become the new task which road freight forwarder should face. Therefore to reinforce the research of road freight transportation problem under the condition that demand is uncertain have very importance meaning on the side of theory and practices.In this thesis, the road freight forwarder is taken as the research object. Starting with the related problems of road freight transportation, the transportation system structure and characteristic, the road freight transportation claims of distinct demands, the transportation method and network structure of stochastic demand, the optimization model, algorithm, analog calculation are analyzed. Through comparative analyzing the hardware and software of road freight transportation problems when demand is certain and stochastic, the weaknesses of the transportation problems when demand is certain are found out. According to the weaknesses, the stochastic programming method is used, then on the basis of the stochastic demand, the thought of multi- frequency goods scheduling is put forward. Based on total transportation cost and time, the model in which the urban traffic conditionare is considered is built with the background of the road forwarder's internal operation network. According to the characteristics of the model, the problem of stochastic demand multi-frequency scheduling is transformed into multi-frequency scheduling problem which demand is certain by using combinatorial method. Then, it is solved by using PSO algorithm. Finally, an example is performed to prove the rationality and feasibility of the model.The purpose of the thesis lies in finding the optimization model and algorithm through studying of the stochastic demand. The research can provide reference and theoretical guidance in the area of improving distribution efficiency and better satisfying the meeting the need of customers for road goods forwarder.