Looking through for errors b4 John Howse submssn
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@ -270,6 +270,11 @@ from base level components cannot be overlooked.
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The process must not allow failure modes to be ignored or forgotten (see project aims in section \ref{requirements}).
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}
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%
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This sub-system or {\dc} $DC$, with its three error modes, can now be treated as a component
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with known failure modes
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(although at a higher level of abstraction).
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This process can be repeated using {\dcs} to build a
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hierarchical fault~mode model.
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The newly derived component $DC$ is available for use to form higher level functional groups, and we can thus
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consider DC as being in the set of components i.e. $DC \in \mathcal{C}$
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@ -277,11 +282,11 @@ consider DC as being in the set of components i.e. $DC \in \mathcal{C}$
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\subsection{Defining the analysis process \\ as a function}
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Where $\mathcal{F}$ is the set of all sets of failure modes, and $\mathcal{DC}$
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Where $\mathcal{FG}$ is the set of all sets of functional groups, and $\mathcal{DC}$
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is the set of all derived components, we can define the symptom abstraction process thus:
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$$
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%\bowtie : SubSystemComponentFaultModes \rightarrow DerivedComponent
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\bowtie : \mathcal{F} \rightarrow \mathcal{DC}
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\bowtie : \mathcal{FG} \rightarrow \mathcal{DC}
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$$
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\paragraph{Extending $\bowtie$ to {\dcs}}
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@ -293,21 +298,38 @@ This generalises the function $\bowtie$ and allows us to build
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hierarchical failure mode models.
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Where a {\fg} is composed of derived components, for sake of example
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where $DC_1, DC_2, DC_3 $ are {\dc}s and $DCFM$ is a set of failure modes thus
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$FG = \{ DC_1, DC_2, DC_3 \}$ and $DCFM = FM(FG)$.
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where $DC_1, DC_2, DC_3 $ are {\dc}s we could collect these into a {\fg} thus
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$FG_{derived} = \{ DC_1, DC_2, DC_3 \}$.
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$DCFM$ is a set of failure modes from the new {\fg} $FG_{derived},$
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$DCFM = fm(FG_{derived})$.
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We can apply the symptom abstraction process $\bowtie$
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to the failure mode set $DCFM$.
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to the {\fg} comprised of derived components
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because we can obtain a failure mode set,
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(the failure mode set we have named $DCFM$).
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Thus we can now move up another abstaction level by applying
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symptom abstraction/extraction to the functional group
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$FG_{derived}$ shown in equation \ref{eqn:fgderived}.
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\begin{equation}
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\label{eqn:fgderived}
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\bowtie ( FG_{derived} ) = DC_{derived}
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\end{equation}
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The case
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where a {\fg} has been created from {\dcs}
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using function `$\bowtie$' leads us to
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{\dc}s at a higher level of fault abstraction.
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{\dc}s at a higher level of failure mode abstraction.
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A notation will be described in the next section
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to keep track of the abstraction level of a {\dc}.
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$$
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%%$$
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%\bowtie : SubSystemComponentFaultModes \rightarrow DerivedComponent
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\bowtie : DCFM \rightarrow DC
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$$
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%%\bowtie : FG_{derived} \rightarrow DC
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%%$$
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%
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%\begin{equation}
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% \bowtie(FG_{cfm}) = DC
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@ -315,14 +337,21 @@ $$
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%
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%or applying the function $fm$ to obtain the $FG_{cfm}$ set
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%
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To put this in context, where FG is a functional group, sourced from base or derived components,
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we may state the process of
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analysing the failure modes in the {\fg} and returning a {\dc} thus:
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\begin{equation}
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\bowtie(fm(FG)) = DC
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\end{equation}
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%%To put this in context, where FG is a functional group, sourced from base or derived components,
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%%we may state the process of
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%%analysing the failure modes in the {\fg} and returning a {\dc} thus:
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%%\begin{equation}
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%% \bowtie((FG)) = DC
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%%\end{equation}
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In other words by analysing a functional group containing derived components
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we have a new derived component as our result.
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This naturally
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builds a bottom-up failure mode model,
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with each iteration the model becomes more abstract will eventually reach
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the SYSTEM level.
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%The $SS_{fm}$ set of fault modes can be represented as a diagram with each fault~mode of $SS$ being a contour.
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%The derivation of $SS_{fm}$ is represented graphically using the `$\bowtie$' symbol, as in figure \ref{fig:gensubsys4}
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@ -334,10 +363,6 @@ analysing the failure modes in the {\fg} and returning a {\dc} thus:
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% \caption{Deriving a new diagram}
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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)
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with known failure modes.
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This process can be repeated using {\dcs} to build a
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hierarchical fault~mode model.
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