Flexibility can be created in manufacturing and service operations by using multipurpose production sources such as cross-trained labor and flexible machines/factories. We focus on control and design issues in systems with flexible resources. In Chapter 2, we consider optimal scheduling of a fully cross-trained server in a finite-population queueing system with multiple, heterogeneous classes of customers, when preemption is allowed. We show that when the customer population is finite, the well-known c.mu rule may not be optimal. We derive conditions under which the c.mu rule is optimal, and we show how the c.mu/lambda ratio can be used to prioritize customer classes. In Chapter 3, we focus on flexible service centers and we propose a new approach to analyzing flexibility arising from the multi-functionality of sources of production. We create a "Work Sharing" network model for which its Average shortest Path Length (APL) metric can predict the more effective of two alternative cross-training structures in terms of customer waiting times. In Chapter 4, we address the issue of how to perform shift scheduling to achieve flexibility in a service center via multi-skilled servers. To do this, we develop a general methodology to approximate the relative flexibility of a queueing system with multi-skilled servers via a Capacitated Flexibility (CF) index. Simulation of a test suite indicates that our proposed CF methodology captures fundamental insights into how to achieve flexibility through service capacity and multi-functionality. In Chapter 5, we study the joint production-inventory control problem of a firm producing two substitutable products in a make-to-stock system. Firm has the option to exercise a one-way substitution to satisfy the customer demands. The joint optimal dynamic policy is shown to have a complex structure. Therefore, we prove the structure of the joint optimal policy for the specific case where the production rates are equal. Furthermore, we construct a multi-threshold policy as a substitute for the optimal policy for the general case. Our numerical study provides insights into the interaction and comparison of flexibility through multi-functional facility (process flexibility) and flexibility through product substitution option (inventory flexibility).

Last modified

• 05/14/2018

Creator

• Bora Kolfal

DOI

• https://doi.org/10.21985/N2PT2R

Subject

• Industrial Engineering and Management Sciences

Keyword

• Operations Research

Date created

• 2007-04-04

Resource type

• Dissertation

Rights statement

• In Copyright