臺灣博碩士論文加值系統

許多學者針對模糊存貨問題作廣泛地探討，本文所探討的模糊存貨問題，在於建立模糊環境下經濟生產批量再訂購點存貨模式；其中使用α截集代表模糊需求，進一步建立模糊總存貨成本函數，尋求最佳的訂購量Q與再訂購點L，使得總成本最小。
依據不同的再訂購點與需求綠的關係，可歸結出五個不同的情況，並一一討論。論文中使用Yager指標排序法，對模糊總存貨成本函數解模糊後，產生總成本指標，以求最小化總成本的訂購量Q與再訂購點L。當需求率為梯形模糊數時，求出全域最佳訂購量Q與再訂購點L；最後以一組數值例子說明，本篇研究的方法可以容易地求解。
本研究將有助於決策者在面臨存貨問題時，得以有效地解決此類問題，提高存貨模式在實務上的應用行；此外，本文的研究方法亦可作為其它模糊存貨模式建構的參考。

Fuzzy inventory problems are often encountered such that they have discussed widely by several scholars. This paper investigates the economics production lot size-reorder point inventory problem with fuzzy demands being fuzzy numbers. The fuzzy demands in this model is presented by the cuts of fuzzy demands and then the fuzzy total inventory cost for finding inventory policy of (Q,L), where Q is the order quantity and L is the reorder point, is constructed. Five cases are discussed depending on different range of L. Then Yager’s ranking index is adopted to find the optimal Q* and L* with minimum index of fuzzy total cost. Moreover, when the fuzzy demand is a trapezoidal fuzzy number, we can derive the closed-form for the global optimal solutions to Q* and L*. Finally, a numerical example is investigated to illustrate the validity of this model. The method proposed in this paper is helpful for decision makers to control inventory problems effectively in fuzzy environments.

Table of Contents

Abstract I
Table of Contents II
List of Figures IV
List of Tables V

Chapter 1 Introduction 1
1.1 Research Motivation 1
1.2 Research Objectives 3
1.3 Research Range 3
1.4 Research Method 4

Chapter 2 Literature Review 8
2.1 Fuzzy Inventory Model Research 8
2.1.1 Fuzzy Inventory Problem in Single Period 8
2.1.2 Fuzzy Inventory Problem under the EOQ model 9
2.2.3 Fuzzy Inventory Problem under the EPQ model 10
2.2 Fuzzy Theory 10
2.2.1 Fuzzy Sets and Membership Function 11
2.2.2 Normal Fuzzy Sets 13
2.3.3 Convex Fuzzy Sets 13
2.2.4 Fuzzy Number 13
2.2.5 α-Cut 13
2.2.6 Extension Principle 14

Chapter 3 Lot Size-Reorder Point Inventory Model in Crisp Environments 15
3.1 Problem Statement 15
3.2 Model Building 16
3.2.1 L≧DT 17
3.2.2 L≦DT 18

Chapter 4 Lot Size-Reorder Point Inventory Model with Fuzzy Demands 22
4.1 The Proposed Model 22
4.2 Transformation 25

Chapter 5 Solution Derivation 27
5.1 Yager’s Index of Fuzzy Total Cost Function 27
5.2 Fuzzy Total Cost Function with Trapezoidal Fuzzy Demands 50
5.3 Numerical Example 60

Chapter 6 Conclusions and Futher Work 64
References 67

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