The Study On Vehicle Routing Problem With Time Windows For Fresh Product

With the developments of the social economic,people's demands for refrigerated products growing.The lost of the product accounts for more than 20 percent during the production,storage,transportation and consuming.To improve their marketing skills, retailers usually restrict the time and quality of the delivery.Considering the time window constraints,distributors also have to take into account some other factors,such as automobile tail gas,the stochastic characteristics that may effect the distribution. Considering these influencing factors,the writer constructs mathematical model to solve the problems of vehicle distribution in fresh produce logistics for the purposes of achieving the minimum cost.The contribution of the thesis is as follows:First of all,based on traditional Vehicle Routing Problem with Time Windows,the writer set up the cost functions,which have considered the following factors:cargo damage cost,punishment cost while dissatisfied the customers' time window constraints, punishment cost by the outlet of automotives,energy cost by refrigerator equipment, fixed cost and transportation cost by the vehicles during the delivery.Secondly,a mathematical model was conducted aiming at minimizing the sum of transportation cost,damage cost,energy cost and penalty cost considering time windows.The coding,crossover,mutating and selecting operations of Genetic Algorithm are designed to solve the problem.For the shortages of traditional Genetic Algorithm,improved Genetic Algorithm of adaptive crossover probability was applied to get optimal solutions.Finally a case study was provided to demonstrate the feasibility of the proposed model and algorithm.This research provides guidance to fresh product logistics distributors on making the optimal shipping decisions such as route selections,vehicle amounts,and delivery time arrangements.