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For meeting with AF 07SEP2012

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Robin P. Clark 2012-09-05 17:22:47 +01:00
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submission_thesis/CH4_FMMD/copy.tex
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@ -83,7 +83,7 @@ This {\dc} has a set of failure modes: we can thus treat it as a `higher~level'
Because a {\dc} has a set of failure modes we can use it in higher level {\fgs}
which in turn produce higher level {\dcs}.
%
We can then use {\dcs} to then build further {\fgs} until a hierarchy of {\fgs}
We can then use these {\dcs} to build further {\fgs} until a hierarchy of {\fgs}
and {\dcs} has been built, converging to a final {\dc}
at the top of the hierarchy.
%
@ -582,8 +582,8 @@ This is represented in the DAG in figure \ref{fig:fg1adag}.
% Potential divider failure modes
%
\node[symptom] (PDHIGH) at (\layersep*2,-1.0) {$PD_{HIGH}$};
\node[symptom] (PDLOW) at (\layersep*2,-3.0) {$PD_{LOW}$};
\node[symptom] (PDHIGH) at (\layersep*2,-1.0) {HighPD};
\node[symptom] (PDLOW) at (\layersep*2,-3.0) {LowPD};
\path (R1OPEN) edge (PDHIGH);
\path (R2SHORT) edge (PDHIGH);
@ -601,7 +601,7 @@ This is represented in the DAG in figure \ref{fig:fg1adag}.
We can now create % formulate
a {\dc} to represent this potential divider:
we name this \textbf{PD}.
This {\dc} will have two failure modes, $PD_{HIGH}$ and $PD_{LOW}$.
This {\dc} will have two failure modes, $HighPD$ and $LowPD$.
% HTR 05SEP2012 We use the symbol $\derivec$ to represent the process of taking the analysed
% HTR 05SEP2012 {\fg} and creating from it a {\dc}.
% HTR 05SEP2012 The creation of the {\dc} \textbf{PD} is represented as a
@ -826,8 +826,8 @@ as {\fcs} in table~\ref{tbl:ampfmea1}.
% Potential divider failure modes
%
\node[symptom] (PDHIGH) at (\layersep*2,-7) {$PD_{HIGH}$};
\node[symptom] (PDLOW) at (\layersep*2,-8.6) {$PD_{LOW}$};
\node[symptom] (PDHIGH) at (\layersep*2,-7) {HighPD};
\node[symptom] (PDLOW) at (\layersep*2,-8.6) {LowPD};
@ -891,30 +891,30 @@ as {\fcs} in table~\ref{tbl:ampfmea1}.
%in hand (say milli-volt signal amplification).
For this amplifier configuration we have three {\dc} failure modes; {\em AMP\_High, AMP\_Low, LowPass}. % see figure~\ref{fig:fgampb}.
This model now has two stages of analysis hierarchy,
as represented in figure~\ref{fig:dc2}.
% HTR 05SEP2012 This model now has two stages of analysis hierarchy, as represented in figure~\ref{fig:dc2}.
From the analysis in table \ref{tbl:ampfmea1} we can create the {\dc} {\em NONINVAMP}, which
represents the failure mode behaviour of the non-inverting amplifier.
\begin{figure}[h]
\centering
\includegraphics[width=225pt]{./CH4_FMMD/dc2.png}
% dc2.png: 635x778 pixel, 72dpi, 22.40x27.45 cm, bb=0 0 635 778
\caption{Hierarchy representing the two stage FMMD analysis
(i.e. two `$\derivec$' processes taking {\fgs} and creating {\dcs}) for the non-inverting amplifier}
\label{fig:dc2}
\end{figure}
% HTR 05SEP2012 \begin{figure}[h]
% HTR 05SEP2012 % HTR 05SEP2012 \centering
% HTR 05SEP2012 \includegraphics[width=225pt]{./CH4_FMMD/dc2.png}
% HTR 05SEP2012 % dc2.png: 635x778 pixel, 72dpi, 22.40x27.45 cm, bb=0 0 635 778
% HTR 05SEP2012 \caption{Hierarchy representing the two stage FMMD analysis
% HTR 05SEP2012 (i.e. two `$\derivec$' processes taking {\fgs} and creating {\dcs}) for the non-inverting amplifier}
% HTR 05SEP2012 \label{fig:dc2}
% HTR 05SEP2012 \end{figure}
We can also represent the hierarchy as an Euler diagram, where the curves
We can represent the hierarchy as an Euler diagram, where the curves
define the components and {\dcs} used to form the INVAMP model, see figure~\ref{fig:eulerfmmd}.
\begin{figure}[h]
\centering
\includegraphics[width=300pt]{./CH4_FMMD/eulerfmmd.png}
% eulerfmmd.png: 413x207 pixel, 72dpi, 14.57x7.30 cm, bb=0 0 413 207
\caption{FMMD analysis of the INVAMP represented as an Euler diagram, showing the relationships between base and derived components.}
\caption{FMMD analysis of the INVAMP represented as an Euler diagram, showing how
the components have been grouped into {\fgs} and then used as {\dcs} to build the analysis hierarchy.}
\label{fig:eulerfmmd}
\end{figure}
@ -927,7 +927,9 @@ down to the base component failure modes, %leaves of the tree (the leaves being
and thus determine all possible causes for
the three high level symptoms, i.e. the failure~modes of the non-inverting amplifier {\dc} {\em INVAMP}.
Knowing all possible causes for a top level event/failure~mode
is extremely useful. Were the top level event to be classified as catastrophic for instance,
is extremely useful.
%
Were a particular top level event to be classified as catastrophic for instance,
we could use this information
to strengthen components that could cause that particular top level event/failure.
%
@ -1455,10 +1457,10 @@ The UML meta model above (see figure~\ref{fig:cfg}) describes a hierarchical str
This is because, as {\dcs} inherit the properties of
components, {\dcs} may be used to form {\fgs}.
%
Consider the hierarchy from the example in figure~\ref{fig:dc2}.
Consider the hierarchy from the example in figure~\ref{fig:eulerfmmd}. % ~\ref{fig:dc2}.
The lowest level in this hierarchy are the {\bcs}, the resistors and the op-amp.
%
The resistors are collected into a {\fg}, and the ${PD}$ derived component created from its analysis, is shown above the {\fg}.
The resistors are collected into a {\fg}, and the ${PD}$ derived component created from its analysis, is shown enclosing R1 and R2. % above the {\fg}.
%
As this derived component inherits the properties of a component, we may use
it in {\fg} higher in the hierarchy.
@ -1468,9 +1470,14 @@ with the op-amp.
%
This {\fg} is now analysed and a {\dc} created to
represent the failure mode behaviour of the {\em INVAMP}.
An analysis report is generated for each {\fg} to {\dc}
process\footnote{By having an analysis report report for each analysis stage, i.e. {fg} to {\dc},
we increase the tracability in the reasoning applied to to the FMEA process.}.
%
An analysis report is generated as part of the {\fg} to {\dc}
process. %\footnote
{By having an analysis report report for each analysis stage, i.e. {\fg} to {\dc},
we add traceability to the reasoning applied to to the FMEA process.}
%
Traditional FMEA has one large reasoning stage, that of component failure mode
directly to system level failure.
%
We may now use the {\em INVAMP} {\dc} in even higher level {\fgs}.