An optimal ordering and recovery policy for direct reusable deterioration items

The quality of product will gradually reduce during the process of recovery. For deterioration items, such rate of deterioration is obvious. However, no scholar studies such phenomenon for direct reusable deterioration items. Nonphysical deterioration always exists in books. This paper observes the character of circulation of books in library, measures the sum of net inventory and online new books with the safe inventory, adopts (s,S) inventory control policy, establishes the Markov-chain of ordering, arriving, lending, returning, scrapping of book. Then, this paper considers the cost of system and the fresh of books, gains the optimal policy of maximum quantity of purchasing and loan span. At last, this paper discusses the future study for direct reusable deterioration items, such as purchasing lead-time, holding span of products, inventory control policy, multi-varieties.