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Degradation Analysis of Probabilistic Parallel Choice Systems
Degradation analysis is used to analyze the useful lifetimes of systems,
their failure rates, and various other system parameters like mean time to
failure (MTTF), mean time between failures (MTBF), and the system failure rate
(SFR). In many systems, certain possible parallel paths of execution that have
greater chances of success are preferred over others. Thus we introduce here
the concept of probabilistic parallel choice. We use binary and -ary
probabilistic choice operators in describing the selections of parallel paths.
These binary and -ary probabilistic choice operators are considered so as to
represent the complete system (described as a series-parallel system) in terms
of the probabilities of selection of parallel paths and their relevant
parameters. Our approach allows us to derive new and generalized formulae for
system parameters like MTTF, MTBF, and SFR. We use a generalized exponential
distribution, allowing distinct installation times for individual components,
and use this model to derive expressions for such system parameters
A probabilistic model checking approach to analysing reliability, availability, and maintainability of a single satellite system
Satellites now form a core component for space
based systems such as GPS and GLONAS which provide
location and timing information for a variety of uses. Such
satellites are designed to operate in-orbit and have lifetimes of
10 years or more. Reliability, availability and maintainability
(RAM) analysis of these systems has been indispensable in
the design phase of satellites in order to achieve minimum
failures or to increase mean time between failures (MTBF)
and thus to plan maintainability strategies, optimise reliability
and maximise availability. In this paper, we present formal
modelling of a single satellite and logical specification of
its reliability, availability and maintainability properties. The
probabilistic model checker PRISM has been used to perform
automated quantitative analyses of these properties
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