1. Operational study data

1.1 Reliability data

A distinction is made between qualitative and quantitative reliability data.

The qualitative approach is more recent, and concerns the description of system architecture from both a hardware and a functional point of view (using expert systems). The hardware aspect is characterized by an inventory of components and a description of their connections, while the functional aspect involves modeling the system's logic, its conditions of use and the behavior of its components using state variables.

The quantitative approach is based on technical, human and economic data. Economic data are important for assessing the cost of restoring components to working order (curative maintenance) and the cost of preventing component...