| With the promotion of fresh food quality and safety policies and the increased consumption of green and healthy food by urban residents,the demand for diversified fresh foods has gradually increased.The high quality requirements of consumers for fresh food have promoted the development of cold chain logistics enterprises.The perishability of fresh food determines the temperature control and timeliness of the distribution process.And the actual road conditions will prolong the distribution time and cause food spoilage and cargo damage,which affects the company's operating efficiency.In order to solve road traffic problems,it is necessary to plan traffic resources rationally and increase road utilization.Among them,the road resistance function can be used to reflect the actual traffic situation of the road,measure the degree of traffic distribution and road network planning,.This function uses the travel time of the vehicle to characterize the degree of traffic smoothness,and can determine the traveler's choice of route and the efficiency of the entire road network.At the same time,enterprises should choose refrigerated trucks with good refrigeration effects and low fuel consumption to complete the cold chain distribution task.Therefore,how to reasonably control the distribution time and optimize the vehicle distribution route under the influence of the road impedance has profound significance for enterprises to improve the distribution efficiency,reduce the loss of cargo damage and reduce the distribution cost.Firstly,the paper classifies and summarizes the research results of cold chain logistics and distribution path optimization problems at home and abroad,expounds the distribution characteristics and operation process of cold chain logistics,and expands the solution methods and basic models of cold chain logistics operation mode and distribution path problems analysis.Then the paper introduces several typical road impedance functions,masters the expression of road impedance,and further analyzes the related influencing factors of road impedance.By analyzing the problems of the traditional BPR function,the relationship between traffic volume and density is used to replace the traffic volume in the function to improve the BPR road resistance function,thereby reflecting the actual traffic conditions and grasping the actual travel time of the delivery vehicle.Then the BPR road resistance function is introduced in the construction stage of the distribution path optimization model,and the minimum total distribution cost is taken as the model optimization goal,which takes into account fixed costs,transportation costs,labor costs,refrigeration costs,cargo damage costs,time window violation penalty costs,and carbon emissions cost element,and the optimization model of cold chain logistics distribution path of fresh food with time window constraint under road impedance is established.Secondly,by analyzing the characteristics of precise algorithm,traditional heuristic algorithm and intelligent optimization algorithm,the paper chooses genetic algorithm with strong adaptive and random search ability to solve the problem of distribution route optimization.Because genetic algorithm is easy to fall into local optimality,in order to improve the local search ability of genetic algorithm,combined with the simulated annealing algorithm in the algorithm design stage,the genetic algorithm is embedded in it,and a hybrid genetic-simulated annealing algorithm is designed to avoid the "premature" problem of the genetic algorithm and improve the overall parallel optimization ability of the algorithm.Finally,taking Yonghui Supermarket as the background case,setting model parameters according to enterprise data,and solving with MATLAB software,the optimal distribution path considering road impedance is obtained,and the operation results of genetic algorithm and hybrid genetic-simulated annealing algorithm are compared and analyzed to verify the effectiveness of the model and algorithm. |
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