Research Of Vehicle Routing Problems With Hard Time Windows

With the rapid economic development,especially the rapid rise of e-commerce,the competition in the logistics and distribution industry and manufacturing enterprises has become increasingly fierce.The vehicle routing problem has received extensive attention as its core issue.As customers demand more and more timeliness for delivery,vehicle routing problems with time windows,especially vehicle routing with hard time windows,have become key research issues.An efficient solution algorithm can help transport and distribution companies to reduce transportation costs,increase business efficiency,and provide customers with more satisfactory services.The problem of vehicle routing with hard time windows as a combinatorial optimization problem has its own complexity,and each constraint condition is mutually restricted,and the research of solving algorithms becomes a difficult problem.This article has conducted the following research on this issue:(1)A new construction heuristic algorithm is designed to overcome the shortcomings of the traditional constructive heuristic algorithm which can easily generate redundant paths.The algorithm consists of three stages: initial path construction phase,insertion phase and exchange operation phase.First,the seed customers are determined using the minimum number of vehicles and the convex hull of the customer's location,instead of the random selection method in the traditional construction algorithm.Second,unlike most construction algorithms,the insertion phase of this algorithm has two insertion processes: In the first process,the unassigned client is iteratively inserted into the optimal insertion position in the initial path regardless of the constraints.Constrain checks and adjustments are performed after insertion;during the second insertion,unscheduled customers are reinserted by considering the free capacity of the path,the customer's demand,and the distance between the unallocated customer and the feasible path.In addition,for customers that cannot be inserted into any feasible path,the operation of swapping operators is introduced instead of directly creating a new path in the conventional algorithm.(2)For the proposed heuristic algorithm in dealing with geographically clustered customers and problems with loose time window and large vehicle capacity,the results obtained are longer driving distances and more problematic vehicles The disadvantages of this article are that the fireworks can be used to carry out information exchange to allocate resources.A vehicle route problem solving technique with time windows is designed based on the improved fireworks algorithm.This algorithm first generates the initial fireworks through the constructed heuristic algorithm(does not perform the swap operation),namely the vehicle path solution,and then calculates the number of sparks that each fireworks explosion can generate based on the different differentiation of each fireworks fitness value.In addition,explosive sparks are generated using cross-reorganization to complete the neighborhood search process in the algorithm;and mutation sparks are introduced to enhance population diversity to improve the search efficiency of the algorithm.(3)The new construction heuristic algorithm proposed in this paper and the solution technology of the vehicle path problem with time windows based on the improved fireworks algorithm are validated using Matlab simulation software on the test dataset of 100 customers of Solomon.The results are compared with the published optimal results of the network,and the results of the two algorithms are compared at the same time to verify the validity of the proposed algorithm.(4)Finally,using Flexsim simulation software to solve the actual delivery case,and compared with the results of the proposed algorithm to verify the feasibility of the algorithm.