Acta Polytechnica Hungarica Vol. 10, No. 1, 2013 – 197 – Optimal Policy for the Replacement of Industrial Systems Subject to Technological Obsolescence – Using Genetic Algorithm Mohamed Arezki Mellal 1 , Smail Adjerid 1 , Djamel Benazzouz 1 , Sofiane Berrazouane 2 , Edward J. Williams 3 1 LMSS, Faculty of Engineering Sciences (FSI), M’Hamed Bougara University, Avenue de l’Indépendance, 35000 Boumerdes, Algeria mellal-mohamed@umbb.dz, adjerid_s@umbb.dz, dbenazzouz@umbb.dz 2 Faculty of Engineering Sciences (FSI), M’Hamed Bougara University Avenue de l’Indépendance, 35000 Boumerdes, Algeria berrazouane_so@umbb.dz 3 College of Business, Decision Sciences, University of Michigan 4901 Evergreen Road, Dearborn, 48126 Michigan, USA williame@umd.umich.edu Abstract: The technological obsolescence of industrial systems is characterized by the existence of challenger units possessing identical functionalities but with improved performance. This paper aims to define a new approach that makes it possible to obtain the optimal number of obsolete industrial systems which should be replaced by new-type units. This approach presents a new point of view compared with previous works available in the literature. The main idea and the originality of our approach is that we apply a genetic algorithm (GA) by considering the failure frequency, the influence of the environment/safety factors of the old-type systems and the purchase/implementation cost of the new-type units. These parameters are introduced in order to optimize this type of replacement in the context of engineering. Keywords: technological obsolescence; industrial systems; replacement policy; failure frequency; safety/environment factors; genetic algorithm (GA) 1 Introduction Often the behavior analysis of industrial systems in engineering is based on the study of monitoring and diagnostics, but technological obsolescence is neglected in the models. Nowadays, technological change is abrupt and the great majority of industrial systems are subject to obsolescence. An item becomes obsolete when a