- 學位論文
A Comparative Study of Storage Allocation Policies and Picking Strategies in Different Warehouse Layouts
A Comparative Study of Storage Allocation Policies and Picking Strategies in Different Warehouse Layouts
摘要
This research investigates the effect of operating policies in traditional and nontraditional warehouse layouts. Operational policies that are considered include storage allocation policy, picking strategy, and picker routing policy. Traditional layouts have vertical picking aisles and cross aisle perpendicular to picking aisles. Nontraditional aisle layouts may have nonparallel picking aisles and inclined cross aisles. Our study considers both unit-load and less-than-unit-load warehouses. For unit-load warehouses, the analysis embraces the assumptions of having multiple P&D points, in combination with random and turnover-based storage policies in different scenarios of demand patterns. Results that the fishbone layout efficiency is slightly better the traditional layouts when there is a P&D point in the lower center and the rest in the upper side of the warehouse. When every P&D point is located in the upper side of the warehouse, the traditional layouts perform the best. We introduce the rotated fishbone (RF) layout for the specific case of having two P&D points at the upper corners of the warehouse. The RF layout shows to be more efficient than other layouts under unit-load operations. Assuming a single centrally located P&D point, we demonstrate that the fishbone layout is able to perform better than traditional layouts for order-picking systems, having a considerable advantage when there is turnover-based storage and the demand pattern of items is noticeably skewed. Our results suggest that warehouses with two P&D points at the upper corners and multi-command cycles are mostly efficient when utilizing a traditional layout with a middle cross aisle. The performance of nontraditional layouts is shown to be very poor for multi-command cycles and two P&D points in the upper corners.
並列摘要
This research investigates the effect of operating policies in traditional and nontraditional warehouse layouts. Operational policies that are considered include storage allocation policy, picking strategy, and picker routing policy. Traditional layouts have vertical picking aisles and cross aisle perpendicular to picking aisles. Nontraditional aisle layouts may have nonparallel picking aisles and inclined cross aisles. Our study considers both unit-load and less-than-unit-load warehouses. For unit-load warehouses, the analysis embraces the assumptions of having multiple P&D points, in combination with random and turnover-based storage policies in different scenarios of demand patterns. Results that the fishbone layout efficiency is slightly better the traditional layouts when there is a P&D point in the lower center and the rest in the upper side of the warehouse. When every P&D point is located in the upper side of the warehouse, the traditional layouts perform the best. We introduce the rotated fishbone (RF) layout for the specific case of having two P&D points at the upper corners of the warehouse. The RF layout shows to be more efficient than other layouts under unit-load operations. Assuming a single centrally located P&D point, we demonstrate that the fishbone layout is able to perform better than traditional layouts for order-picking systems, having a considerable advantage when there is turnover-based storage and the demand pattern of items is noticeably skewed. Our results suggest that warehouses with two P&D points at the upper corners and multi-command cycles are mostly efficient when utilizing a traditional layout with a middle cross aisle. The performance of nontraditional layouts is shown to be very poor for multi-command cycles and two P&D points in the upper corners.