Several Kinds Of Inventory Models Based On Time Value Of Money And Their Optimization

With the development of world economic integration and market globalization, scientific production planning and inventory control not only has become an important issue for the modern enterprises but also makes many scholars focus on the issue. Nowadays, world economics is suffering from large scale of inflation, the time value of money is changing from time to time, which can not be ignored for enterprise to make management decisions. In this thesis, some inventory models under inflationary conditions are studied, to provide valuable suggestions on management decisions for enterprises and help them reduce cost and keep away from hazard resulting form inflation and time value of money.The main contents are as follows:In Chapter 1, we firstly introduce the control elements of inventory system, the effect of inflation on social economics and the definition of time value of money and discount rate. Then, the recent researches on inventory models based on time value of money are briefly reviewed, and the main results of the thesis are summarized.In Chapter 2, following the Discounted Cash Flow approach, a deterministic inventory model for deteriorating items with time-dependent backlogging rate and time value of money is presented. The aim is to determine the optimal replenishment number and order quantities which minimize the present value of the total cost. Then the character of the model is analyzed and an algorithm to find the optimal replenishment policy is provided. Finally, numerical examples are presented to illustrate the model and sensitivity analysis for parameters is also given.In Chapter 3, an inventory lot-sizing model is developed for deteriorating items over a fixed planning horizon, where the Discounted Cash Flow approach is used to fully recognize the financial implication of the opportunity cost and out-of-pocket costs. The demand rate is assumed to be influenced by inflation. Shortages are allowed with partial backlogging. The necessary condition which minimizes the total system cost is presented. Then the model is simplified, and an effective solution procedure is provided. Finally, a numerical example and sensitivity analysis are shown to illustrate the model.In Chapter 4, under the assumptions that the lost rate during the shortage period is proportional to the quantities of the factual backorder and the demand rate depends on inflation and time. An inventory lot-sizing model is presented for deteriorating items to minimize the present value of total system cost, where the Discounted Cash Flow approach is used. Then, incorporating different constraint of service level, another two models are developed respectively.Next, the character of the three models is analyzed and algorithms to find the optimal replenishment policy are given. Finally, numerical examples are shown to illustrate the validity of the models.In the end, the research work is summarized, and some suggestions about further research on inventory model with time value of money are made.