Linearly Correlated Intermittent Failures

In reliability calculation, the general assumption is to regard the behavior of redundant systems as (statistically) s-independent. This considerably simplifies the mathematics involved, but limits the usefulness of the results as s-dependence can appreciably impact the system reliability. This paper introduces two measures, using linear correlation, to describe the s-dependence of intermittent failures. One measure relates to the linear correlation for the entire period during which faults are active in different modules; the other measure relates to the closeness in time of the instants faults become active in different modules. Characteristics and their relationship with reliability and fault processes of these measures are considered. Irreversible processes corresponding to permanent failures are examined.