An integrated simulation-DEA algorithm for layout optimization

In this study, an integrated Simulation-Data Envelopment Analysis (DEA) approach is presented to deal with a job shop facility layout design problem for an Iranian gas company. In this workshop, it is considered that the some parts of production equipment fail to operate and it is necessary to repair them, as soon as possible. The process of repairing these parts includes different operations on different facilities and the optimal layout of facilities in maintenance shop can reduce the process time. The layout problem in this system involves determining the location of all maintenance shop facilities. Layout optimization plays a crucial role in this type of problems in terms of increasing the efficiency of the main production line. To do so, different types of layout is considered including U-shaped, S-shaped, W-shaped, Z-shaped, and straight line layouts. First, the system is modeled with discrete-event-simulation as a powerful tool for analyzing complex systems. Time in system (TIS), average waiting time (AWT), average machine utilization (AMU), average availability (AA) of facilities, average length queue of facilities (AL) and average operator utilization (AOU) are obtained from simulation as key performance indicators (KPIs). Also, safety is considered as another KPI in this article. Finally, a unified non-radial Data Envelopment Analysis approach is presented with respect to the set of comprehensive indicators obtained in previous steps in order to rank all proposed layouts to find the best configuration of facilities.