Research On The Equipment Configuration And The Inventory Control In The Distribution Center Based On The Random Demand

Modern logistics is the important component of the modern economics, and the most economical and reasonable integrated service mode. As the important link in the logistics system, distribution center attracted a wide spread, and a lot of enterprise set up their own distribution center, and many third party logistics distribution centers are established, and the traditional transportation ways like as the railway are engaged in the research of building the modern distribution center. Distribution center connect the suppliers and the consumers, which is the bridge. It's very useful for the whole logistics system to optimize the equipment configuration, to control the inventory cost, to decrease the operating cost and to improve the service level of the distribution center.Based on the careful analysis of the routine operating flow of the distribution center and the relative research at home and abroad, and in order to effectively allocate the basic equipment in the distribution center, to improve operation efficiency, and to decrease operation cost, and considering the character that there are a lot of uncertain factors in the routine work of the distribution center, this paper selectively researches several basic problems in the process of construct and the routine work in the distribution center by the stochastic process theory and computer simulation. The research contents include as following:Firstly, this paper researches the problem how to optimize the equipment configuration based on direct shipping strategy. For the problem of the equipment configuration under the order of first come first serve, this paper calculates the average time length of delivery cycle of the distribution center by the tandem queuing, and constructs the model to optimize the equipment configuration based on the queuing theory with the goal of minimizing the total cost, and with the restrictive condition to delivery the freight on time. For the problem of the equipment configuration under the order of priority service, this paper sets the service ways for different customs according to the operating features of different sectors of the distribution center, and calculates the average time length of delivery cycle of the distribution center, and constructs the model to optimize the equipment configuration based on the queuing theory with the goal of minimizing the total cost. For the equipment configuration under the two orders of serve, this paper designs the search steps based on the enumeration method to find the optimal value. This paper exploits two simulation programs to simulate the delivery process of the distribution center under the order of first come first serve and the order of priority service according to their actual operation situation by matlab language, and constructs their simulation models and then optimizes their solutions.Secondly, this paper researches the problem how to optimize the equipment configuration based on package transportation strategy. For the problem of the equipment configuration under the condition of instant departure, this paper analyzes the situation to pick goods and the change of the quantity of the goods waiting for delivery, and deduces the necessary and sufficient condition of operation stationary of the distribution centre, and calculates the average time length of delivery cycle of the distribution center, and constructs the model to optimize the equipment configuration based on the queuing theory with the goal of minimizing the total cost. For the problems of the equipment configuration under the condition of the no full load departure and the full load departure, this paper calculates the average time length of delivery cycle of the distribution center, and constructs the model to optimize the equipment configuration based on the queuing theory. For the equipment configuration under the three conditions of departure, this paper designs the search steps based on the enumeration method to find the optimal value. This paper exploits three simulation programs to simulate the delivery process of the distribution center under these condition of departure according to their actual operation situation by matlab language, and constructs their simulation models and optimizes their solutions.Thirdly, this paper researches the spots inventory control problem with the continuous demand. This paper constructs the continuous inventory control model without the service level constraint with the goal of minimizing the total inventory cost. In the process of solving the problems, according to three common demand types in the lead time such as the uniform distribution, the exponential distribution and the normal distribution, we calculate the average backorder quantity in one order cycle, and with the intermediate variable of safety factor, we deduce the calculation formulas of these indexes such as optimal order point and optimal order quantity. This paper constructs the continuous inventory control model with the service level constraint with the goal of minimizing the total inventory cost. We look the demand quantity service level as the known parameter, and with the intermediate variable of safety factor, we deduce the calculation formulas of these indexes such as optimal order point and optimal order quantity under the demand condition such as the uniform distribution, the exponential distribution and the normal distribution.Finally, this paper researches the two echelon inventor control problem considering the delivery process. The two echelon inventor control system is composed by one distribution center and some retailers, and the response time is affected not only by the inventory control strategy of the distribution center but also by the performance ability of the distribution center and the arrival intensive degree of the distribution demand. Based on the careful analysis of the operating situation of the system, constructs the inventory control simulation model with the service level constraint and with the goal of minimizing the total cost, and exploits the simulation programs and optimizes their solutions with the genetic algorithm.