Symptom reliability and hazard for systems condition monitoring

Quite recently the authors of this paper defined the concept of symptom rel iability for systems in use or in operation, which means that the reliabili ty is based on symptoms of the systems under consideration. This symptom-de pendent reliability is quite different from the commonly known lifetime-bas ed reliability. But despite the lack of definition it is a quantity already used in the practice of machine condition monitoring [1]. Following this c oncept, the symptom-dependent hazard functions are introduced, and proposal s are made for their use. This provides the opportunity to link the symptom reliability with other covariates associated with the systems usuage, such as load and maintenance quality, which are not contained explicitly within the symptom values or lifetimes. This will allow condition determination a nd prediction to be made more reliably and accurately, and it will make sys tems usage more economical than before. (C) 2000 Academic Press.