Optimization Of Cold Chain Vehicle Route Problem With Time Window

With the high-speed growth of China’s residents’ consumption level since the new century,people have more pursuit and higher standards in the aspect of daily life.Coupled with the influence of the COVID-19 epidemic,it has promoted the change of people’s consumption psychology,and the increase of the demand for fresh products across the country,which has also increased people’s demand for cold chain distribution.However,the high requirements are proposed by fresh foods such as meat,milk,vegetables and fruits for storage and distribution temperature accuracy.To solve the problems of the high damage rate and large demand,it requires a more rapid,efficient and punctual cold-chain logistics distribution scheme,which is the main goal of fresh product distribution at present.The research of this thesis is carried out in view of the cold-chain vehicle routing problem of brightdairy Dairy Co.,Ltd.’s fresh leading logistics in Jinan City.In the process of investigating its distribution status,most of the large supermarkets it serves are found to lack scientific planning in the distribution process,and the low loading rates of some vehicles lead to the resource waste.What’s more,the failure to complete the delivery operation within the specified time causes the increase of the goods shortage window of large modern supermarkets,the increase of the discount rate of fresh products,and the reduction of customers’ loyalty to the brand,so the decline of brand market share is finally aroused.To solve this problem,a scientific and optimal distribution route should be planned for brightdairy Dairy Co.,Ltd.to reduce the company’s distribution expenses in logistics and improve the consumption satisfaction of the people under the condition of timely delivery.In this thesis,the vehicle routing problem of dairy products distribution in the brightdairy Dairy Co.,Ltd.of Jinan is researched.Firstly,the current supply chain and business process of brightdairy Dairy Co.,Ltd.are analyzed,and the problems existing in fresh leading logistics distribution of brightdairy Dairy Co.,Ltd.are summarized.Then,the features of its dairy products that need to control the temperature throughout the whole process,the demand points have extremely high requirements for delivery time and so on,the description is conducted from the vehicle routing problem and the corresponding assumptions are given.The minimizing of the fixed and variable costs of vehicles,the minimizing of the cost of vehicle refrigeration,the minimizing of the cost of goods damage and the related quantification of time windows are taken as the goals to construct a multi-objective cold chain vehicle distribution constraint model with time windows.Secondly,a genetic algorithm with better global search ability is selected to solve the problem,and the selection operator in the genetic operator is improved.The probability of individuals with higher fitness being selected is increased by adopting the method of multiple roulette wheel,making the algorithm results closer to the actual distribution situation of brightdairy Dairy Co.,Ltd.while avoiding falling into local optimal solution.Finally,actual operational data from brightdairy Dairy Co.in Jinan was used as experimental data and verified through simulation using Matlab software.This study compared an improved genetic algorithm with a basic genetic algorithm,based on selection operators,and found that the improved genetic algorithm can significantly shorten the delivery distance to large supermarkets,increase the average loading rate of vehicles,optimize all costs of cold chain logistics,meet the mixed time window requirements of large supermarkets,and enhance the competitiveness of brightdairy Dairy Co.in the dairy industry.