Evaluation and Optimization of Two-Stage Continuous Transfer Lines Subject to Time-Dependent Failures*

Abstract

This paper addresses the performance evaluation and optimization of continuous flow transfer lines composed of two machines separated by a buffer of finite capacity. Machines are subject to time-dependent failures. Times to repair and times to failure of the machines are random variables with general distribution. For the purpose of performance evaluation, a set of evolution equations that determines continuous state variables at epochs of discrete events is established. Based on the evolution equations, we prove the concavity of the throughput rates of the machines and derive gradient estimators. Unbiasedness and strong consistency of the gradient estimators are proved. Finally, an design optimization problem that maximizes a concave function of throughput rate and a design parameter is addressed.