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Robin Clark 2010-06-07 16:49:54 +01:00
parent a404a9210b
commit a9a4c254e1

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@ -249,9 +249,9 @@ take a given component $C$ and return its set of failure modes $F$.
$$ FM : C \mapsto F $$
\begin{definition}
We can define a set $U$ which is a set of sets of failure modes, where
We can define a set $\mathcal{U}$ which is a set of sets of failure modes, where
the component failure modes in each of its members are unitary~state.
Thus if the failure modes of $F$ are unitary~state, we can say $F \in U$.
Thus if the failure modes of $F$ are unitary~state, we can say $F \in \mathcal{U}$.
\end{definition}
\section{Component failure modes:\\ Unitary State example}
@ -271,7 +271,7 @@ Thus because both fault modes cannot be active at the same time, the intersectio
$$ R_{SHORTED} \cap R_{OPEN} = \emptyset $$
therefore
$$ FM(R) \in U $$
$$ FM(R) \in \mathcal{U} $$
We can make this a general case by taking a set $F$ (where $f_1, f_2 \in F$) representing a collection
@ -283,7 +283,7 @@ We can say that if any pair of fault modes is active at the same time, then the
unitary state:
we state this formally
\begin{equation}
\forall f_1,f_2 \in F \dot ( f_1 \neq f_2 \wedge \mathcal{ACTIVE}({f_1}) \wedge \mathcal{ACTIVE}({f_2}) ) \implies F \not\in U
\forall f_1,f_2 \in F \dot ( f_1 \neq f_2 \wedge \mathcal{ACTIVE}({f_1}) \wedge \mathcal{ACTIVE}({f_2}) ) \implies F \not\in \mathcal{U}
\end{equation}
@ -293,7 +293,7 @@ we state this formally
% \end{equation}
That is to say that it is impossible that any pair of failure modes can be active at the same time
for the failure mode set $F$ to exist in the family of sets $U$.
for the failure mode set $F$ to exist in the family of sets $\mathcal{U}$.
Note where that are more than two failure~modes,
by banning any pairs from being active at the same time
we have banned larger combinations as well.
@ -382,8 +382,8 @@ for each component in the functional group under analysis.
For example: were we to have a simple functional group with two components R and T, of which
$$FM(R) = \{R_o, R_s\}$$ and $$FM(T) = \{T_o, T_s, T_h\}$$.
This means that a functional~group $FG=\{R,T\}$ will have a component failure modes set % $FM_{cfg} $
of $FM_{cfg} = \{R_o, R_s, T_o, T_s, T_h\}$
This means that a functional~group $FG=\{R,T\}$ will have a component failure modes set
of $FG_{cfg} = \{R_o, R_s, T_o, T_s, T_h\}$
For a cardinality constrained powerset of 2, because there are 5 error modes ( $|{FG_{cfg}}|=5$),
applying equation \ref{eqn:ccps} gives :-
@ -432,9 +432,12 @@ where :
that are members of the functional group $FG$
i.e. $ \forall j \in J | C_j \in FG $
\item Let $|{C}_{j}|$
indicate the number of mutually exclusive fault modes each component has
\item Let $SU$ be a set of unitary state failure modes from the functional group
nder analysis $SU = FM(FG)$
indicate the number of mutually exclusive fault modes of each component
\item Let $FG_{cfg}$ be the collection of all failure modes
from all the components in the functional group.
\item Let $SU$ be a set of failure modes from the functional group,
where all contributing components $C_j$
are guaranteed to be `unitary state' i.e. $(SU = FG_{cfg}) \wedge (\forall j \in J | C_j \in \mathcal{U}) $
\end{itemize}
%}