A Research On Several Types Of Inventory Control Models

Inventory management is an important component part of an enterprise'production and operation management. Not only does it have a direct effect on the turnover of floating capital ,but also plays a very significant role in ensuring to meet all the customers'requirements. The core of inventory management lies in reducing the total cost of inventory system, improving service level and strengthening enterprises' competitiveness. As science & technology and economy develop, inventory management has been endowed with more meanings and functions and has been one of the research focuses of the academic and business circles, and its theories and methods have developed.Management strategies of single-stage and multi-stage inventory system are studied in this paper. Single-stage production inventory system and single-stage marketing inventory system are the study objects of single-stage inventory system management strategy. The research on single-stage production inventory system focuses on management strategies of industry and aquaculture inventory systems, where three kinds of EPQ models with exponential time-varying demand and different partial backlogging as well as an inventory model for pig-typed ameliorating item with time-varying unit holding cost are developed. Two EOQ models with controllable lead time and setup cost, and partial backlogging rate relative to price discount are presented in the study of single-stage marketing inventory system. A VMI integrated model for deteriorating items with partial backlogging related to customers' waiting time is proposed in the part of study of multi-stage inventory system management.The main innovation points of this paper can be summarized as follows:Firstly, three kinds of EPQ models with different partial backlogging are developed, including an EPQ model with variable production rates, an EPQ model for deteriorating items with partial backlogging in inverse proportion to inventory level during shortage, and an EPQ integrated model for deteriorating items with partial backlogging related to production status.Secondly, an inventory model for pig-typed ameliorating item with linearly time decreasing unit holding cost is initially developed, where the weight unit(kg) is the unit of inventory level, and the length of raising period is decision variable. The rules of inventory changing and net ameliorating of PIC pig are analyzed and finally a numerical example is given. The achivements can be used to guide the production and operation practices of pig raising enterprises and provides decision support in helping them cut down operating cost and raise social and economic profits.Thirdly, based on partial backlogging rate related to both inventory level and price discount during shortage, two EOQ models with controllable lead time are developed, among which one is an EOQ model with controllable lead time and setup cost under periodic check, and the other is an EOQ model with controllable lead time and setup cost under continuous check. These two models are tested under different types of customers' demands.Lastly, a VMI integrated model for deteriorating items is presented where the buyer's partial backlogging is negatively relative to customers' waiting time as well as the supplier purchases material once for several production cycles, or the supplier purchases material several times just for one production cycle, and the supplier's production quantity is an integral number of the order quantity of the buyer.