A passive diagnostic experiment with ergodic properties

During the elaboration of vibration condition monitoring procedures for critical machinery one has to apply the so-called passive diagnostic experiment. To model such an experiment, either as a set of units, or as one unit several stages of operation and or repair cycles, one can consider the respective machines as energy processors. With the theory of the ergodic equivalence of observation, it can be concluded that both considerations lead to the same results, taking into account the possible realisations of the logistic vector. Using the simulation, it is possible to show that the symptom models used in vibration condition monitoring, for condition recognition and prediction, can be in most cases limited to Weibull and Frechet models. (C) 1997 Academic Press Limited