Summary: Flexible Servers in Tandem Lines with Setups
SigrŽun AndradŽottir · Hayriye Ayhan
H. Milton Stewart School of Industrial and Systems Engineering
Georgia Institute of Technology
Atlanta, GA 30332-0205, U.S.A.
School of Management
State University of New York-Binghamton
Binghamton, NY 13901-6000, U.S.A.
We study the dynamic assignment of flexible servers to stations in the presence of setup
costs that are incurred when servers move between stations. We focus on tandem lines
with two stations and two servers with the goal of maximizing the long-run average profit.
We investigate how the optimal server assignment policy for such systems depends on the
magnitude of the setup costs, as well as on the homogeneity of servers and tasks. More
specifically, for systems with either homogeneous servers or homogeneous tasks, small buffer
sizes, and constant setup cost, we prove the optimality of "multiple threshold" policies (where
servers' movement between stations depends on both the number of jobs in the system
and the locations of the servers) and determine the values of the thresholds. For systems
with heterogeneous servers and tasks, small buffers, and constant setup cost, we provide