Research On Vehicle Routing Problem Under Uncertain Environment

With the rapid development of the internet e-commerce transactions and the logistics industry,the competition among enterprises is becoming more and more fierce,and the value of time is increasing.Real-time,dynamic and efficient modern logistics has become an important indicator to measure the economic efficiency of a company,a region and even a country.As one of the core issues in the operation of modern logistics system,the vehicle routing problem has attracted the attention of both the industry and academia since its birth.After nearly half a century of development,the vehicle routing problem has evolved from the initial single vehicle routing problem to the current multi-objective vehicle routing problem with complex constraints.At the same time,many research branches have derived.Vehicle routing problem under the uncertain environment is an important type of extension in many branches.The following research work was carried out around this extended type of paper:Firstly,after studying a large number of related domestic and foreign literature on vehicle routing problem,the uncertain information in the vehicle routing problem is divided into three types:transmission environment,data environment and road network environment under uncertain environment.on the basis of introducing the theoretical knowledge related to the thesis,the representative algorithms for solving vehicle routing problem are introduced in detail from three aspects of thought,characteristics and development.Secondly,aiming at the three uncertain environ:ments,in the transmission environment aspects,the network signal transmission expectation-variance mathematical Imodel and the fuzzy shortest path critical edge mathematical model under uncertain environments are established;In the data environment aspects,a mathematical model of dynamic vehicle routing problem with time windows under uncertain environment is established;In the road network environment aspects,a mathematical model with time-dependent dynamic vehicle routing problem with soft time window is established.Then,five test functions are used to test the performance of the improved ant colony algorithm,and the improved ant colony algorithm is applied to solve the actual network signal transmission case;To further improve the search speed of the optimal solution,the sweep algorithm and the improved ant colony algorithm are combined to solve the dynamic vehicle routing problem with time windows in the actual cases;In order to describe the change of vehicle speed with time in actual logistics distribution more effectively,and take into account the stochastic factors such as road traffic jam and weather change that affect the vehicle speed as far as possible,the traditional particle swarm optimization algorithm is improved,and the sweep algorithm and the improved particle swarm optimization algorithm are combined to solve the actual logistics distribution cases and the international standard test set.Finally,on the basis of summarizing the main research work of the thesis,the innovations and shortcomings of the thesis are expounded,and the research direction of the vehicle routing problem under uncertain environment is pointed out.