倉儲系統(tǒng)控制技術(shù)中英文資料外文翻譯文獻(xiàn)-閱讀頁
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【正文】 pecially equipped for the storage and orderpicking of small items. A carousel consists of storage positions that rotate around a closed loop thereby delivering the requested SKU39。10]. 752 van den Berg 2. Planning of warehouse operations In this section we focus on the storage location assignment problem at the tactical level. The procedures that are developed at this level, serve as a framework for the actual location selection for ining goods. In these procedures, the behavior on the intermediate term is estimated by historical demand patterns. Since the storage location assignment problem will be intractable as a whole, we introduce the hierarchical four step Storage Location Planning Location Planning Procedure 1. Distribution of products among warehousing sys tems. 2. Clustering of correlated products. 3. Balancing of workload within warehousing systems. 4. Assignment of products to storage locations. We discuss relevant literature on the successive steps in Sections to . . Distribution of products among warehousing systems Most large warehouses contain more than one type of warehousing system. Each warehousing system is especially equipped for a speci?c group of products based on their characteristics, such as: size, weight, shape, perishability, volume, demand rate, pick sizes, delivery quantity, type of storage module, et , many warehouses use separate systems or areas for orderpicking (forward area) and for bulk storage (reserve area). Whenever a product in the forward area has been depleted, it is replenished from the reserve area. A wellknown forwardreserve con?guration is a storage rack where the lower levels are used for manual orderpicking (forward area) and the higher levels contain the bulk storage (reserve area).Bozer [11] treats the problem of splitting a pallet rack into an upper reserve area and a lower forward area. The author assumes Chebyshev travel times (., the travel time of the pallet truck is the maximum of the isolated horizontal and vertical travel times) and a ?xed picklife for all unitloads in the forward area. He shows when a separate reserve area is justi?ed. He also studies the case with variable unitload sizes and a remote reserve area. He analytically derives the breakeven value for the picklife of a unitload, which is of potential use in deciding which products to consider for the forward area. Hackman and Rosenblatt [12] present a model where orderpicking from the reserve area is possible. Accordingly, the question arises which products should be picked from the forward area and how much space must be allocated to each of these products. The objective is to minimize the total costs for orderpicking and replenishing. The authors assume that one replenishment trip su?ces to replenish a product, irrespective of the allocated quantity. The authors derive analytic expressions for the optimal product quantities as a function of the available storage space. They present a knapsackbased heuristic that assigns these quantities to the forward area in sequence of decreasing cost savings until it is full
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