| Distribution Centers (DC) or warehouses is an essential component of anylogistics system, major roles including: receiving material, storage them and orderpicking according to the customers' requests in which the latter part is the most basicfunction in distribution center. Order picking-the process of retrieving products fromstorage or buffer areas in response to a specific customer request-has long beenidentified as the most labor-intensive and costly activity for almost everydistribution center. The cost of order picking is estimated to be as much as 60% ofthe total distribution center expense presented by Tompkins, 2004. Anyunderperformance in order picking can lead to unsatisfactory service and highoperational cost for the distribution centers which are the environment of muchsmaller order and more frequently request, and consequently for the logistics system.In order to operate efficiently, the order picking process needs to be robustlydesigned and optimally controlled. This paper bring forwards the special mode ofDC's configuration after introducing and summarizing the researches foretime aswell as investigating order picking operations of some modern distribution centers.Three kinds of problem formed: routing/sequencing (under the configuration of UnitLoad AS/RS, MOB AS/RS and Carousels System), batching picking and zoningpicking problem owing to the key factors of configuration, including picking area,storage policies, rack/aisle layout and picking machine et al. Due to different pickingoperations strategy and optimization objectives, these problems come into beingdifferent mode with different traits. We focus on modeling some of these problemsand presenting an exact polynomial algorithm for "easy" ones and heuristicsalgorithm for the "hard" ones. At last, all these solvable algorithms will be simulatedor experimented for its performance so that implemented successfully in practice inlogistics system.
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