had to write this down

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Robin Clark 2010-12-10 10:37:45 +00:00
parent 8c485650ad
commit 2281c2d95a

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@ -1148,6 +1148,21 @@ an attribute to the failure~modes must be added
that can reference other failure~modes and environmental conditions.
An UML diagram with inhibit conditions added is shown in figure \ref{fig:umlconcept2}.
\subsection{Safe Dangerous, Detected and Undetected.}
The top level or SYSTEM failure modes can be examined and
assigned SIL~\cite{en61508} safe and dangerous attributes.
Detected failure modes appear as symptoms that have been
integrated into symptoms involving self checking.
Undetectable failure modes, will follow a direct line
up from component level to SYSTEM level without being
incorporated into a self checking functional group.
These undetected failures correspond to a minimal cut
set where a single base~component failure mode
can be traced to a SYSTEM level failure mode.
They can thus be determined by searched the DAG
for a single base~component failure mode minimal cut set~\cite{nucfta}.
% UML DIAGRAM
\begin{figure}[h]