Strategic Intra-Logistics Optimization in Large-Scale Assembly Facilities
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Zeng, Yulian
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Abstract
The rapid growth in industrial production and the need for efficient logistics management have highlighted significant challenges in intra-logistics centers design and operations. Traditional approaches often fall short in addressing the stochastic requirements and complexities of modern logistics systems. This dissertation aims to address these challenges by proposing innovative solutions for optimizing logistics facility layouts and configurations, enhancing operational efficiency, and reducing overall costs.
In chapter 2, we concentrate on optimizing the dimensions and configuration of an inbound parts storage center in an assembly factory that stores modular containers. This center employs block stacking alongside racking systems for container storage. Given storage and throughput requirements for each part and stacking constraints, the objective is to determine the center size (rows, row length & depth) and the assignment of parts to stack locations to minimize total handling and space costs. We use a mixed-integer programming model (MIP) and introduce a heuristic approach to optimize the warehouse layout. The results of a large-scale experiment based on a major-brand carmaker factory are reported.
In chapter 3, we address the block stacking storage optimization problem using a simulation optimization approach. The total cost including area cost and material handling cost is used as the performance measure. We incorporate a heuristic algorithm into the simulation technology to design the layout and compare eight configuration options for 2 days restock cycle time vs various restock cycle time, deterministic vs stochastic consumption/inter-arrival time, shared vs dedicated storage policy. In order to implement the shared storage policy optimally, we also propose a new inventory control policy and compare different bays assignment policies. We report on the results of a large-scale experimentation based on the carmaker factory.
In chapter 4, we address the logistics facility configuration problem by defining protomodels. Protomodels are preliminary layout models that specify the relative locations of storage centers. Once a protomodel is established, we configure the logistics center by setting the dimensions of the storage centers and the flow of parts. We then optimize each center using a center optimization algorithm, such as block stacking optimization, rack optimization, floor optimization, or flow rack optimization. The overall objective is to minimize the total cost across all centers. The protomodel configuration algorithm is highly efficient, and we present the results of six protomodels using data from a large vehicle assembly factory.
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2024-09-06
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Dissertation (PhD)