損耗性產品存貨模式的研究相當多，但有關商品有效期限的問題很少被提出討論，在實際環境中有許多商品，如食品、藥品等都存在有效期限的問題，是存貨管理不可忽視的課題。另外，在現實環境中，供應商提供一付款寬限期給買家已經是很普遍的現象，即買家在購買商品後可以不必立刻付款，於期限到期時再付款，此種提供買家延遲付款期限的策略不論是對供應商或買家而言，皆有一定的好處。此外，在存貨文獻中較少有關斜坡型需求的研究，所謂斜坡型需求，即一般新產品剛上市時，需求率常隨著時間向前移動而遞增，直到某一時點之後，需求才會呈平穩狀態，而這樣的假設也較接近實際狀況。 基於上面現實的考量，本研究建構了三個具斜坡型需求且補貨率與需求有關的損耗性產品存貨模式，在第二章中，我們考慮商品存在有效期限的問題；第三章我們假設允許延遲付款；第四章則同時考慮商品存在有效期限且允許延遲付款。我們以單位時間平均成本最低為目標，分別建立數學模式，文中對所建構的數理存貨模式利用傳統的最佳化原理找出最適的訂購策略。最後，以數值範例說明模式的求解過程並對各參數做敏感性分析。 A large number of researchers developed the models in the area of deteriorating inventories, but most researches in inventory did not consider the expiry date of items. In real business behavior, there are many commodity such as food, medication exist the expiry date. Therefore the existence of the expiry date has become an important research topic in production and inventory management. In addition, it is a very common practice to allow customers some grace period before they settle the account with the supplier. This practice is beneficial to both the customers and the suppliers. On the other hand, there are only a few models have been developed considering ramp-type demand in the inventory literature. This type of demand pattern is generally seen in the case of any new brand of consumer goods coming to the market. The demand rate for such items increases with time up to certain time and then ultimately stabilizes and becomes constant. It is believed that such type of demand rate is quite realistic. Base on the hypotheses we mentioned above, this study develops three inventory models for deteriorating items with a ramp-type demand and the finite production rate is proportional to the demand. In chapter 2, we assumed the existence of the expiry date. In chapter 3, we assumed that a delay in payment is permissible. In chapter 4, we assumed that a delay in payment is permissible and the existence of the expiry date. The object is to find the minimum cost per unit time. In the study, mathematical models are also derived. The optimal solution procedures for the present problems are provided. Numerical examples are presented to illustrate the models, and the sensitivity analysis of the optimal solution with respect to parameters of the systems are also carried out.
