Looking through for errors b4 John Howse submssn

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Robin Clark 2010-10-30 12:29:15 +01:00
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commit c3e8946c39

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@ -270,6 +270,11 @@ from base level components cannot be overlooked.
The process must not allow failure modes to be ignored or forgotten (see project aims in section \ref{requirements}). The process must not allow failure modes to be ignored or forgotten (see project aims in section \ref{requirements}).
} }
% %
This sub-system or {\dc} $DC$, with its three error modes, can now be treated as a component
with known failure modes
(although at a higher level of abstraction).
This process can be repeated using {\dcs} to build a
hierarchical fault~mode model.
The newly derived component $DC$ is available for use to form higher level functional groups, and we can thus The newly derived component $DC$ is available for use to form higher level functional groups, and we can thus
consider DC as being in the set of components i.e. $DC \in \mathcal{C}$ consider DC as being in the set of components i.e. $DC \in \mathcal{C}$
@ -277,11 +282,11 @@ consider DC as being in the set of components i.e. $DC \in \mathcal{C}$
\subsection{Defining the analysis process \\ as a function} \subsection{Defining the analysis process \\ as a function}
Where $\mathcal{F}$ is the set of all sets of failure modes, and $\mathcal{DC}$ Where $\mathcal{FG}$ is the set of all sets of functional groups, and $\mathcal{DC}$
is the set of all derived components, we can define the symptom abstraction process thus: is the set of all derived components, we can define the symptom abstraction process thus:
$$ $$
%\bowtie : SubSystemComponentFaultModes \rightarrow DerivedComponent %\bowtie : SubSystemComponentFaultModes \rightarrow DerivedComponent
\bowtie : \mathcal{F} \rightarrow \mathcal{DC} \bowtie : \mathcal{FG} \rightarrow \mathcal{DC}
$$ $$
\paragraph{Extending $\bowtie$ to {\dcs}} \paragraph{Extending $\bowtie$ to {\dcs}}
@ -293,21 +298,38 @@ This generalises the function $\bowtie$ and allows us to build
hierarchical failure mode models. hierarchical failure mode models.
Where a {\fg} is composed of derived components, for sake of example Where a {\fg} is composed of derived components, for sake of example
where $DC_1, DC_2, DC_3 $ are {\dc}s and $DCFM$ is a set of failure modes thus where $DC_1, DC_2, DC_3 $ are {\dc}s we could collect these into a {\fg} thus
$FG = \{ DC_1, DC_2, DC_3 \}$ and $DCFM = FM(FG)$. $FG_{derived} = \{ DC_1, DC_2, DC_3 \}$.
$DCFM$ is a set of failure modes from the new {\fg} $FG_{derived},$
$DCFM = fm(FG_{derived})$.
We can apply the symptom abstraction process $\bowtie$ We can apply the symptom abstraction process $\bowtie$
to the failure mode set $DCFM$. to the {\fg} comprised of derived components
because we can obtain a failure mode set,
(the failure mode set we have named $DCFM$).
Thus we can now move up another abstaction level by applying
symptom abstraction/extraction to the functional group
$FG_{derived}$ shown in equation \ref{eqn:fgderived}.
\begin{equation}
\label{eqn:fgderived}
\bowtie ( FG_{derived} ) = DC_{derived}
\end{equation}
The case The case
where a {\fg} has been created from {\dcs} where a {\fg} has been created from {\dcs}
using function `$\bowtie$' leads us to using function `$\bowtie$' leads us to
{\dc}s at a higher level of fault abstraction. {\dc}s at a higher level of failure mode abstraction.
A notation will be described in the next section
to keep track of the abstraction level of a {\dc}.
$$ %%$$
%\bowtie : SubSystemComponentFaultModes \rightarrow DerivedComponent %\bowtie : SubSystemComponentFaultModes \rightarrow DerivedComponent
\bowtie : DCFM \rightarrow DC %%\bowtie : FG_{derived} \rightarrow DC
$$ %%$$
% %
%\begin{equation} %\begin{equation}
% \bowtie(FG_{cfm}) = DC % \bowtie(FG_{cfm}) = DC
@ -315,14 +337,21 @@ $$
% %
%or applying the function $fm$ to obtain the $FG_{cfm}$ set %or applying the function $fm$ to obtain the $FG_{cfm}$ set
% %
To put this in context, where FG is a functional group, sourced from base or derived components, %%To put this in context, where FG is a functional group, sourced from base or derived components,
we may state the process of %%we may state the process of
analysing the failure modes in the {\fg} and returning a {\dc} thus: %%analysing the failure modes in the {\fg} and returning a {\dc} thus:
\begin{equation} %%\begin{equation}
\bowtie(fm(FG)) = DC %% \bowtie((FG)) = DC
\end{equation} %%\end{equation}
In other words by analysing a functional group containing derived components
we have a new derived component as our result.
This naturally
builds a bottom-up failure mode model,
with each iteration the model becomes more abstract will eventually reach
the SYSTEM level.
%The $SS_{fm}$ set of fault modes can be represented as a diagram with each fault~mode of $SS$ being a contour. %The $SS_{fm}$ set of fault modes can be represented as a diagram with each fault~mode of $SS$ being a contour.
%The derivation of $SS_{fm}$ is represented graphically using the `$\bowtie$' symbol, as in figure \ref{fig:gensubsys4} %The derivation of $SS_{fm}$ is represented graphically using the `$\bowtie$' symbol, as in figure \ref{fig:gensubsys4}
@ -334,10 +363,6 @@ analysing the failure modes in the {\fg} and returning a {\dc} thus:
% \caption{Deriving a new diagram} % \caption{Deriving a new diagram}
This sub-system or {\dc} $DC$, with its three error modes, can now be treated as a component (although at a higher level of abstraction)
with known failure modes.
This process can be repeated using {\dcs} to build a
hierarchical fault~mode model.