The Reseach Of Vehicle Routing Problem With Simulaneous Pickup And Delivery, Stochastic Demands, Time Windows

The researches on the vehicle routing problems and the facility location problems are very important parts of the logistics networks optimization.These two classes of problems are significant on the economic area and military area.In the classical logistics networks optimization,the researchers mainly focused on the deterministic problems.The problems are very simple,even though they considered the uncertainty elements.In the real life,there exist much uncertainty information and many complex constraints.Traditional models and algorithms show great limitations in solving the stochastic problems and dynamic problems.Therefore,it is necessary to do further research jobs to construct more effective models and algorithms for the stochastic logistics networks optimization and the dynamic logistics networks optimization.In this thesis,a series of stochastic vehicle routing problems and a dynamic location allocation problem are studied thoroughly.In order to achieve maximizing revenue and rationalizing the cost,the use of simultaneous Pick-up and Delivery vehicle distribution is the trend of modern logistics development.In addition,as consumer demand tends to be personalized and diversified the demand for service time is increasing harsh reduced customer satisfaction caused by the delay in service time is a hidden cost that highlights the importance of time window in the distribution process.This paper is based on the stochastic demands and constraints of the time windows,with the goal of minimizing the delivery costs of vehicles on the path,a vehicle routing model with time windows under random demand is constructed.Based on the ant colony algorithm,the article also designs an ant colony system optimization algorithm that combines the ant colony and the neighborhood search algorithm,and analyzes the actual background.The main contents are as follows:Through the literature review of predecessors,this paper illustrates the background of this research question,expounds the research status quo of the related issues,and puts forward the questions to be studied in this background and current situation.At the end of the article,the research frame,technical route and basic assumptions of this topic are given.Based on the above background and the status quo,this paper established the subject of this paper,under the stochastic demands of vehicles with a time window routing optimization problem.In order to facilitate the research,the article first makes a series of reasonable assumptions,describes the service failure rules,and then analyzes theobjective function and constraints,and constructs the 0-1 integer programming model.Considering the dynamic problems in the real production activities,this paper proposes a decomposition method,that is,a staged model of "first static and then dynamic real-time re-optimization",which transforms the problem in dynamic environment into the static problem identified in stages And insert the dynamic information at the end moment of each time period that the vehicle performs the task,and adjust the driving route of the vehicle in real time according to the current location of the vehicle and the updated information so as to optimize the optimization goal.Aiming at the problem of static stochastic demand,a hybrid ant colony optimization algorithm is used to solve the problem.Finally,an example of a model algorithm is also given to an enterprise in Hangzhou as a background.Stochastic demand under multi-period and quasi-dynamic traffic conditions Case scenario design,verify the basic theory of the previous article.The results of the example show that the proposed algorithm is feasible and effective and has certain guidance under the decision-making environment with variable traffic conditions and customer demand.It can guide the real-time express enterprises to some extent.