Research On VRPSDP Online Strategy With Uncertain Pickup Demand

VRPSDP(Vehicle routing problem with simultaneous pickups and deliverys)is the academic and logistics concerns of the hot issues.The existing theoretical results on VRPSDP is mainly based on the assumption that the delivery demand and deliverys are completely known,and a static optimization model is established and the heuristic algorithm is designed to solve them.However,the actual throughput may be uncertain;For the study of the uncertainty of the pick-up demand,it is usually assumed that the pick-up demand follows a distribution and seeks the optimal solution in the average sense.This may give a solution that is far away from the actual optimal solution and can not meet the actual demand.In view of the lack of existing research,this paper considers the situation of uncertainty of pickups,adopts the theory and method of online problem and competition strategy,studies from the unpredictable and limited predictions of pick-up demand,designs online strategy and analyzes the execution of strategy Effect,provide the decision-making basis for the logistics transportation company to formulate the route selection plan.The main work and innovative results are as follows.Aiming at the unpredictable pick-up demand of vehicles and each demand point can only serve once,the paper put forward the problem of VRPSDP of on-line vehicles while unpredicting the quantity of deliverys.As many as possible goals to establish an online vehicle routing model to analyze the situation can not be unloaded halfway and two cases can be unloaded,and for two different situations were designed the Large amount of priority strategy and Half-way unloading strategy.Proves Large amount of priority strategy competition ratio is 1 /(?-?-(n-1)?),the competition ratio of Adjusting the remaining space of the vehicle strategy under the condition of half-way unloading is 1 /(?-?).The comparative analysis shows that the execution effect of Half-way unloading strategy is better than Large amount of priority strategy.Aiming at the pick-up demand can be limit look-ahead of the vehicle by the demand of VRPSDP and the service of each demand can only be served once,the problem of obtaining the online vehicle routing while taking the limited quantity of cargo is put forward.That is to say,the vehicle departs from the distribution center and is known before departure Delivery per demand point,but only when a certain demand point is reached is it possible to know the demand point and the next upcoming arrival demand,only serve once per demand point and fulfill all demand point delivery tasks returning to the distribution center,it aims to make the total amount of pickups as large as possible.and establishes the online route selection model of delivery vehicles while taking the limited forecast of the pickup demand,and analyzes the two situations of unloading and half-way unloading in the midway,and designs the Select large strategy and two different scenarios respectively PUPI strategy and prove the competition ratio of the strategy,Select large strategy competition ratio is 1 /(?-?-(n-1)?),and the competition ratio of PUPI strategy is 1 /(?-(m +t)?).In the end,we analyze the PUPI strategy under Select unimportant situation and the PUPI strategy under the condition of unloading,and find that PUPI strategy performs better than Select large strategy in the case of unloading.Finally,an example is given to verify the validity of the strategy.The strategy designed in this paper is the strategy of VRPSDP with the uncertainty of pick-up information,which can provide the decision-making basis for the logistics transportation enterprises to formulate the route selection plan.