Ankara : The Department of Industrial Engineering and the Graduate School of Engineering and Science of Bilkent University, 2012.Thesis (Master's) -- Bilkent University, 2012.Includes bibliographical references leaves 62-64.In this thesis, we study a two stage flow shop problem with a single server. All jobs
are available for processing at time zero. Processing of a job is preceded by a
sequence independent setup operation on both machines. The setup and
processing times of all jobs on the two machines are given. All setups are performed
by the same server who can perform one setup at a time. Setups cannot be
performed simultaneously with job processing on the same machine. Once the
setup is completed for a job, processing can automatically progress without any
further need for the server. Setup for a job may start on the second machine before
that job finishes its processing on the first machine. Preemption of setup or
processing operations is not allowed. A job is completed when it finishes processing
on the second machine. The objective is to schedule the setup and processing
operations on the two machines in such a way that the total completion time is
minimized. This problem is known to be strongly NP-hard [3]. We propose a new
mixed integer programming formulation for small-sized instances and a Variable
Neighborhood Search (VNS) mechanism for larger problems. We also develop
several lower bounds to help assess the quality of heuristic solutions on large
instances for which optimum solutions are not available. Experimental results
indicate that the proposed heuristic provides reasonably effective solutions in a
variety of instances and it is very efficient in terms of computational requirements.Kolay, MuhammetM.S
