| It is clear that a material handling system has a significant influence on the overall performance of a manufacturing system. In order to obtain the best overall system performance, the reliability and availability (R&A) of the material handling system is critical. However, there have been difficulties in evaluating R&A of material handling systems due to the fact that they exhibit stochastic behavior that includes degrading performance over time. Many analytical models have been proposed for the evaluation of R&A of complex degradable material handling systems, however, they are not adequate for a variety of reasons including mathematical complexity, excessive numerical computation, and inability to model transient behavior. Because of the limitations and restrictions of analytical performance models, simulation has been often used as an analysis and evaluation method in the design and operation of large and complex manufacturing systems.; This dissertation presents a simulation-based performance evaluation approach based on the PI method proposed by Usher (2000). The PI method is developed by applying a quadratic loss function, often referred to as “Taguchi loss function”, to characterize the impact of component failures and repair processes on the overall performance of a material handling system. First, the dissertation derives the confidence interval estimates of PI for the three types of performance characteristics, i.e. nominal-is-best, larger-is-better, and smaller-is-better. Next, the effectiveness of PI in two different situations is analyzed, i.e. the performance evaluation of a single system and performance evaluation in comparison of alternative systems. For the performance evaluation of a single system, factor screening experiments, designed to identify the system components whose failure and repair most impact performance, is investigated. For the comparison of alternative systems, a time-based PI approach is proposed. The approaches are illustrated through the analysis of a large and complex distribution center. |
