“…Each of these entities would generate specific unexpected events that are related to them. A number of authors: [18,21,23,27,30,31,32,33,34,35,36,37,38,39] have identified a number of unexpected events and partially or completely agree with Darmoul et al [26]. In the literature, an additional specific unexpected event, production time variation, has also been proposed [ 21,23,25,31,37,38].…”