9. Glossary

Availability, operating status; up state

A condition characterized by the ability to function as required.

State of unavailability, state of failure; down state

A condition characterized by inability to function as required.

Instantaneous availability, A(t)

Probability of being available at a given time.

Instantaneous unavailability, U(t)

Probability of being unavailable at a given time.

Disponibilité moyenne; average availability, A ^moy (T )

Average value of availability A(t) over the interval [0, T ]. Average availability can also be defined over an interval [t ₁ , t...