Study On Route Optimization Of Express Vehicle Routing Problem With Simultaneous Pickup And Delivery Under Interval Road Network Impedance

Nowadays,the express industry faces three challenges to realize efficient and reliable service.First,with the rapid development of Internet technology and the significant improvement of people's living standards,customers have increasingly high requirements on express delivery timeliness,and the express industry needs to provide more efficient logistics services to satisfy the customer needs.Second,the policies of green logistics require improving the resource utilization rate of the express industry.The express industry needs a more perfect scheduling plan to make full use of vehicle resources and avoid unreasonable transport phenomena such as empty driving,convection and detour.Third,traditional express vehicle scheduling ignores the uncertainty of road network traffic impedance,which is easy to cause decision-making risk.It is necessary to fully consider the uncertainty of the actual road network impedance,avoid the congested road sections and improve the logistics efficiency.Considering the uncertainty of road network impedance,the vehicle routing problem with simultaneous pick-up and delivery is studied.In this thesis,the interval number is used to measure the uncertainty of road network traffic impedance,and the robust deviation criterion,namely the maximum regret value,is applied to define the robust cost of vehicle path.On this basis,a robust optimization model of the vehicle routing problem with simultaneous pick-up and delivery based on minimum and maximum regret is constructed.Considering that the calculation of robust cost requires the determination of vehicle path in advance,this thesis designs a Benders decomposition algorithm.In this algorithm,the model is decomposed into the main model and the sub-model,which fix the route with the upper and lower bound impedance respectively,so as to calculate the upper and lower bound of the robust cost,and the gap is reduced to zero through iteration.The results show that the model and algorithm work well.Finally,the model and algorithm is testified in Y express company.The results show that the proposed vehicle scheduling scheme is more robust than the original one.The robust optimization model and algorithm proposed in this thesis take full account of the uncertainty of road network traffic impedance and have good practical value for express vehicle scheduling.The proposed method can be extended to other vehicle routing problems and has good theoretical significance.