Research On Optimal Dispatch Of Commodities Shipping In Beijiang River Based On In-transit Inventory

Since the implementation of the "double transfer" strategy in Guangdong Province and the demonstration project of green bulk cargo transport in Beijiang,a large number of bulk cargo enterprises have built new manufacturing bases in the northern part of Guangdong Province and along the Beijiang River,which has led to a substantial increase in demand for bulk cargo transport in Beijiang.At present,the transportation volume of cement,ceramics,building materials and coal in the Qingyuan section of Beijiang River has increased from 6.97 million tons in 2011 to 39.09 million tons in 2017 and maintained a high growth rate.Beijiang bulk cargo transportation has the following characteristics: 1)relatively fixed types of cargo and routes.Beijiang bulk cargo enterprises often use convective transportation from initial port located in the upper reaches of Beijiang River to unloading port located in the Pearl River Delta,and loading raw materials back to the initial port;2)long period of cargo transportation,ships from the initial port to unloading port need half a month to return.(3)Beijiang bulk cargo enterprises often adopt the same dispatching cycle as the transportation cycle,which means arranging the next transportation after the completion of a transport;4)there are three lock hubs in the main stream of Beijiang River,but the size of the lock is small and the capacity of the lock is limited.Considering the characteristics of Beijiang bulk cargo transportation,when the average daily water transportation demand of enterprises is 20,000 tons and the transportation cycle is 15 days,the in-transit inventory of enterprises reaches 300,000 tons.Therefore,the impact of in-transit inventory on ship dispatching of Beijiang bulk cargo enterprises can not be ignored.In addition,in the busy season of Beijiang transportation,the transit time of ships will fluctuate significantly,which may lead to delays in transport planning for several days.Therefore,the uncertainty of transport time is also an important factor that enterprises need to consider when dispatching ships.It can be found that the existing dispatching system of Beijiang bulk cargo enterprises,which does not take these two factors into account,is still imperfect.Based on the demonstration project of Beijiang Green Transport of bulk cargo,this paper takes in-transit inventory and the uncertainty of transportation time into consideration.Firstly this paper constructs a ship optimal dispatching model with the objective of minimizing transportation cost,inventory cost,ship cost and dispatching cost,based on in-transit inventory and determination of transportation time.Then the uncertainties of transportation time are further considered.An opportunity-constrained programming model is constructed with adding safety inventory and expected delay cost in objective.Taking the daily ship transportation dispatch of Y company of a cement enterprise in Beijiang as an application case,the following conclusions are drawn:(1)Considering in-transit inventory and the determination of transportation time,Y company can reduce the total cost by 11.7 million RMB(Reduced by 6.7%)in the planning period(90 days)by adjusting the ship transportation dispatch scheme.(2)Considering the uncertainties of transportation time in the peak season of transportation,the optimized dispatch scheme can reduce the total cost of Y enterprise by 1.89 million yuan and 3.41 million yuan respectively in the short-time requirements and long-term requirements in the planning period.(3)Considering ship dispatching under in-transit inventory and uncertain transportation time,Y enterprise improves the dispatching level by setting up safe inventory,using larger tonnage ships and shortening the corresponding dispatching cycle.