同步分區揀貨系統是一種揀貨後再分類的訂單揀貨系統，此系統能將同一批量的訂單中的物品，在不同存貨的區域由不同的揀貨員同時進行揀貨。而在揀取物品後，這些物品會根據其揀貨完成順序在緩衝區內合併成一個批量。合併後的批量會進入物品分類站並依照個別的顧客訂單進行分類。本研究提出一個以等候理論為基礎之近似模型來計算單一批量待在揀貨系統中的期望時間。此模型之揀貨區的服務時間可以使用任何一種機率分配、揀貨方式來進行估計。而在分類過程中，假設在每一項物品皆需透過分類掃描器進行分類且分類時間為固定常數。接著，藉由有系統的分析方法可以整理出分類站的特性，依據這些特性可以計算出一個批量中個別顧客訂單的平均完成時間。本研究所提出的兩種理論模型，將透過模擬研究來驗證其準確性。而這兩個模型將可以幫助系統設計者來評估不同數量的揀貨區、批量大小以及每一批量的訂單數量在同步分區揀貨系統中造成的影響。

Synchronized zone picking systems are pick-and-sort order picking systems, where items of orders in the same batch are processed simultaneously in different zones by a group of labors. After retrieval, these items are accumulated in the buffer area according to their associated batches. These consolidated batches then enter the sorting station to be classified into individual customer orders. In the picking process, an approximate model based on queueing theory is developed to estimate the expected throughput time of a batch from the arrival to departure of the zone picking area. In this model, the service times in zones can follow any probability distributions. In the sorting process, an analytical method is used to evaluate the expected time from a batch of items into individual customer orders, where the scan time to distinguish each item is assumed to be constant. The two proposed methods in the two processes are validated by simulation studies to check the accuracy. These provided models will help system designers to measure the effect of the number of zones, the batch size and the number of orders in one batch.

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