以排序法求解模糊經濟訂購量模式

Solving the Fuzzy Economic Order Quantity Model via Ranking Method

存貨管理攸關企業經營的成敗，在實際的存貨問題中，經常面臨各式各樣的不確定性或模糊性。自從Bellman與Zadeh提出模糊理論以來，即有多位學者將其使用於傳統的存貨模型中，以期得到更廣泛的應用。近年來，Vujoševic等人將訂購量視為模糊數值，再利用重心法將此模糊數值解模糊化以求得明確的訂購數量。而本研究則直接處理存貨總成本的模糊數值，利用Yager 的模糊數值排序法，以求解經濟訂購量。經由數值範例顯示，本研究的方法所求得的訂購量其所對應的總成本之模糊數值，會較Vujoševic等人所求得之結果為小。而且當模型中各參數的模糊數值退化成明確數值時，本研究所提的方法將會與傳統的經濟訂購量模式相同，故其必能提高存貨模式在實務上的應用。

Inventory management plays an important role for most of the business or ganizations. In practice, various types of uncertainties or fuzziness are inherent in real inventory problems. Since the fuzzy set theory proposed by Bellman and Zadeh, several scholars have constructed different fuzzy inventory models and proposed the associated solution methods for wider applications. Recently, Vujoševic et al. treated the order quantity as fuzzy number, then the economic order quantity (EOQ) was solved by the centroid method. In this paper, Yager’s ranking method is utilized to derive the order quantity in terms of the fuzzy inventory costs. The results from the illustrative example show that the proposed method has lower total costs than that of the Vujoševic model. Furthermore, if the fuzzy numbers of the parameters for the model are crisp values, the solution derived from the proposed method will be the same as the conventional EOQ model. With this methodology, more real world inventory problems can be solved.