Research On Integrated Optimization Problems Of Inventory And Transportation

Since both inventory cost and transportation cost are important components of the supply chain cost, inventory control and distribution management are two significant fields in supply chain management. The high complexity of the real world problems increases the difficulty of solving inventory control and distribution management. Thus the traditional literature of company or supply chain operation usually takes them as two independent parts.Vendor managed inventory provides a new operation scheme for supply chain management. In this scheme, through advanced information technique, the supplier can acquire the inventory information of the retailers instantly and correctly, so that it can optimize the overall inventory of the supply chain system and decide the reasonable distribution plan from the system point. Based on vendor managed inventory, our dissertation discusses several familiar problems of the inventory and transportation integrated optimization. However, the literature usually focuses on the centralized supply chain, so that the theoretic research is difficult in applying to the practical supply chain operations. This dissertation considers of the noncentralized supply chain, mainly researches on the problems of inventory and transportation optimization based on vendor managed inventory. Here is the main research work of the dissertation.(1) It considers the optimal ordering strategy of inventory and transportation integrated optimization in a two-echelon decentralized supply chain consisting of one supplier and one retailer. It discusses three scenarios: decentralized decision, centralized decision and coordination decision based on price discount policy. Models and algorithms are proposed respectively. Numerical example shows that the price discount policy can increase the profits of both sides and implement the cooperation of the supplier and the retailer.(2) It considers the payment problem of transportation cost in the inventory and transportation integrated optimization. In a decentralized supply chain of one supplier and one retailer, three scenarios of inventory and transportation integrated optimization (ideal centralized supply chain, transportation cost paid by supplier and transportation cost paid by retailer) are discussed and modeled. Random numeric experiments prove that more supply chain profit can be obtained when the retailer pays transportation cost and the profit of supply chain is very close to the profit in ideal centralized supply chain. In order to attract the retailer to agree to pay transportation cost, profit division strategy is adopted to make sure both supplier and retailer obtain more profit.(3) It discusses the pricing problem of the inventory and transportation integrated problem under an elastic demand and sensitive price environment. Suppose the supplier is dominant in the supply chain, it considers pricing, inventory and transportation cost simultaneously under the price sensitive environment. It analyses non-cooperation decision and centralized decision models respectively. It designs two coordination strategies, revenue sharing and price discount, to appropriately divide the system profit to both parties to make sure of their cooperation. The experimental results show: comparing with the supplier-Stackelberg game structure, centralized cooperation decision can greatly increase the system profit. Through revenue sharing and price discount strategy, the system coordination can be implemented efficiently and the increased system profit can be appropriately divided to the retailer and the supplier.(4) It considers the inventory routing problem without considering the supplier's inventory. In a two-echelon decentralized supply chain with one supplier and multi-retailers, it models the inventory and transportation integrated optimization problem, and proposes a modified nearest neighbor algorithm in order to increase the whole profit of supply chain by decreasing the transportation cost and inventory cost. It designs a proper pricing strategy, proposes the upper and lower bounds of the prices, reallocates the profit of the supply chain to the supplier and the retailers, thus realizes"multi-win"and improves supply chain coordination.(5) It considers the inventory routing problem considering the supplier's inventory cost. In a two-echelon supply chain with one supplier and multi-retailers, the retailers and the supplier have inventory costs. It discusses how to implement the integrated optimization of inventory and transportation, analyses the decentralized and centralized decision scenarios respectively, builds the mathematical models and designs heuristic algorithms. The research results show that centralized decision is superior to decentralized decision, and can save a great deal of cost for the supply chain.