MEADEP: a dependability evaluation tool for engineers

MEADEP (measure dependability) is a user-friendly dependability-evaluation tool for measurement-based analysis of critical systems. MEADEP consists of 4 software modules: a data preprocessor for converting data in various formats to the MEADEP format, a data analyzer for graphical data-presentation and parameter estimation, a graphical modeling interface for building block diagrams (including the exponential block, Weibull block, and k-out-of-n block) and Markov reward chains, and a model-solution module for availability/reliability calculations with graphical parametric analysis. Use of the tool on failure data, from measurements provides quantitative evaluations of dependability for the target system, while greatly reducing requirements for specialized skills in data-analysis and system-modeling from the user. MEADEP has been applied to evaluate availability for two air-traffic control systems based on operational failure data; the results have provided valuable feedback to the project management of these critical systems. MEADEP has been used to analyze a nuclear power-plant safety model, based on the Eagle 21 architecture and its early field-failure data. The study identified the most sensitive parameter and its most sensitive value segment to the plant mean time between hazards.