The integration of line loading and material handling.

摘要

This thesis investigates the integration of line loading and material handling in a deterministic, multi-product, multi-stage, multi-period manufacturing system, with the presence of both processing and material transport capacity constraints. The problem is to decide, for each processing period, jobs and their quantities to be loaded on the workstations, and the material handling system operating details, such that the capacity constraints on both the workstations and the material handling system are not violated, and overall system operating cost is minimized. The manufacturing lines, along with the material handling system, are modeled as time expanded networks. The problem is then transformed into that of finding the minimum cost flows on a multi-commodity flow network with strong side constraints. Reentrant material flows and alternate processing routes are explicitly considered in the model. Techniques for reducing problem sizes, and heuristics for expediting solution processes are proposed. The rolling-horizon-based reduction, which exploits the way operational plans are implemented in reality, can often significantly reduce the problem size and are applicable to other similar operational planning problems. The thesis also addresses the issue of system nervousness caused by data revision and rolling horizons.