Some Remarks on Optimum Inspection Policies

Inspection policies : comparisons and modifications

“…We must obtain the inspection procedure which balances costs for inspection and system down, i. e., the optimum inspection policy which minimizes the total expected cost composed of costs for inspection and system down. Based on this point of view, several papers for inspection policies have been published [1][2][3][4][5][6][7][8][9][10].…”

“…( However, this algorithm by Barlow et al is complicated to be executed, because one must apply trial and error to décide the first inspection time t x and the assumption to f(t) is really strong* To overcome these difficultés, some improved procédures to obtain the nearly optimum inspection policy have been proposed [3][4][5][6][7][8]. For example, Keiler [3] proposed the nearly optimum inspection policy introducing a smooth density which présents the number of inspections per unit time.…”

“…For example, Keiler [3] proposed the nearly optimum inspection policy introducing a smooth density which présents the number of inspections per unit time. Further, Kaio and Osaki [4] have developed Keller's method using the smooth density, which is called inspection density, and obtained the more analytically exact nearly optimum inspection policy. Munford and Shahani [5] have obtained the nearly optimum inspection policy assuming that the probability of the failure occurence between the successive inspections is constant.…”

“…For example, inspection model where the System may be incapable of detecting its failure due to imperfect inspection has been considered [4,9]. Kaio and Osaki [4] have considered the inspection model with checking time. Wattanapanom and Shaw [10] have discussed the inspection model in which the System détériorâtes by each inspection.…”

“…In Section 2, we numerically compare the optimum inspection policy by Barlow et al [1,2] with nearly optimum ones by Kaio and Osaki [4], Munford and Shahani [5], and Nakagawa and Yasui [8], assuming a gamma lifetime distribution. In Section 3, we treat a modified inspection model taking account of two kinds of imperfect inspection probabilities, and obtain the structure of the optimum inspection policy, and discuss the optimum policy minimizing the total expected cost up to the détection of the failure.…”