Wednesday night edit

This commit is contained in:
Robin Clark 2010-11-24 19:58:05 +00:00
parent 80df6f9548
commit 7da97e6a68
6 changed files with 134 additions and 15 deletions

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@ -292,9 +292,10 @@ would have an $\alpha$ value of 1.
Let the set of all possible components be $\mathcal{C}$
and let the set of all possible failure modes be $\mathcal{F}$ and $\mathcal{PF}$ is the powerset of
all $\mathcal{F}$..
all $\mathcal{F}$.
We can define a function $fm$ as equation \ref{eqn:fmset}.
\label{fmdef}
\begin{equation}
fm : \mathcal{C} \rightarrow \mathcal{P}\mathcal{F}
@ -763,6 +764,7 @@ operational states.
The additional objects System, Environment and Operational States
are added to UML diagram in figure \ref{fig:cfg} and represented in figure \ref{fig:cfg2}.
\label{completeuml}
\begin{figure}[h]
\centering

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@ -8,31 +8,53 @@
%% What I have done
%%
This paper presents a simple two stage Failure Mode Modular De-Composition (FMMD)
model of a theoretical System.
The Analysis model is then represented as a Directed Acyclic Graph (DAG), of the {\fg}s
components and failure modes represented in it.
%% What I have found
% What I have found
%%
From traversing the DAG, minimal cut sets (component level combinations
that cause system level failures) are revealed.
Common mode failure modes and same component dependencies
can also be automatically determined.
%% Sell it
%%
}
}
By having a clear data model, we can not only produce results
for the traditional methodologies, we can trace common mode and
component dependency failures as well.
Also, with statistical data, we can use the minimal cut set results
to determine the likelihood of particular system failures, even
if they have multiple causes.
} % abstract
} % ifthenelse
{
%%% CHAPTER INTO NEARLT THE SAME AS ABSTRACT
\section{Introduction}
This chapter
presents a simple two stage FMMD % Failure Mode Modular De-Composition (FMMD)
model of a theoretical System.
The Analysis model is then represented as a Directed Acyclic Graph (DAG), of the {\fg}s
components and failure modes represented in it.
%% What I have done
% What I have found
%%
%% What I have found
%%
%and considering some constraints determined from
%the evaluation of the four established methodologies,
From traversing the DAG, minimal cut sets (component level combinations
that cause system level failures) are revealed.
Common mode failure modes and same component dependencies
can also be automatically determined.
%% Sell it
%%
By having a clear data model, we can not only produce results
for the traditional methodologies, we can trace common mode and
component dependency failures as well.
Also, with statistical data, we can use the minimal cut set results
to determine the likelihood of particular system failures, even
if they have multiple causes.
}
%{ \huge This might become a chapter in its own right after fmmdset }
@ -60,7 +82,7 @@ represents the FMMD hierarchy level, or $\alpha$ value, thus:
}
{
We can organise these into functional groups (where the superscript
represents the $\alpha$ value, see section \ref{alpha}), thus:
represents the $\alpha$ value, or FMMD hierarchy level, see section \ref{alpha}), thus:
}
$$ FG^0_1 = \{C_1, C_2\},$$
@ -68,10 +90,28 @@ $$ FG^0_2 = \{C_1, C_3, K_4\},$$
$$ FG^0_3 = \{C_5, C_6, K_7\}.$$
Note that in this model the base~component $C_1$ has been used in
two separate functional groups.
two separate functional groups. This could be a component that they
both commonly use. A real world example of a component included in
more than one {\fg} could
be a powersupply or DCDC\footnote{A DCDC (direct current to direct current)
converter, is a common feature in modern PCBs, used to provide isolation
and/or voltage supplies at a different EMF from the source of power.}
converter shared to power
the functional groups $FG^0_1$ and $FG^1_1$.
Also that the component type $K$ has been used by
two different functional groups.
For the sake of example let our temperature environment
for the SYSTEM be ${{0}\oc}$ to ${{125}\oc}$, but let the component
type `K' have a de-graded performance failure mode between
${{80}\oc}$ and ${{125}\oc}$\footnote{ A real world example of
degraded performace with temperature is the isolating opto coupler.
These can typically only cope with lower baud rate ranges
at high temperatures \cite{tlp181}.}. We can term this
degraded performce of component `K' as failure mode `d'.
\paragraph{Symptom Extraction.}
A processes of symptom extraction is now applied to the functional groups.
Again for the sake of example, let us say that each functional
@ -81,6 +121,83 @@ Applying symptom abstraction to $FG^0_1$ i.e. $\bowtie fm ( FG^0_1 ) = \{ FG^0_{
We can now create a new derived component, $DC^1_1$, whose failure
modes are the symptoms of $FG^0_1 $ thus $ fm ( {DC}^1_1 ) = \{ FG^0_{1 a}, FG^0_{1 b} \} $.
\paragraph{Building the Object Model}
Using the UML model in figure \ref{fig:cfg2fmmd_data} we will apply FMMD analysis stages
to build a hierarchy representing the whole system, begining with the $FG^0$ level functional groups.
\begin{figure}[h]
\centering
\includegraphics[width=400pt,bb=0 0 702 464,keepaspectratio=true]{./fmmd_data_model/cfg2.jpg}
% cfg2.jpg: 702x464 pixel, 72dpi, 24.76x16.37 cm, bb=0 0 702 464
\caption{UML Class model for FMMD}
\label{fig:cfg2fmmd_data}
\end{figure}
% %\begin{figure}[h]
% \centering
% \includegraphics[width=400pt,keepaspectratio=true]{./fmmd_data_model/cfg2.jpg}
% % cfg2.jpg: 702x464 pixel, 72dpi, 24.76x16.37 cm, bb=0 0 702 464
% \caption{Complete UML diagram}
% \label{fig:cfg2fmmd_data}
% \end{figure}
\paragraph{Find Failure Modes}
Consider the SYSTEM environment with its temperature range of ${{0}\oc}$ to ${{125}\oc}$.
We must check this against all components used.
For our example, we component `K' which has an extra
failure mode for degraded performance `d'.
\ifthenelse {\boolean{paper}}
{
We can definine a `failure modes' function $fm$ that has a functional group as its range
and returns a set of failure modes as its domain.
We now use this to determine the failure modes
in our functional groups.
}
{
Using the overloaded function $fm$ from chapter \ref{fmdef} we can determine the failure modes
in our functional groups.
}
Applying the function $fm$ to our functional groups, with the SYSTEM environmental
constraint applied to component type `K', yields
%%//$$ FG^0_1 = \{C_1, C_2\},$$
%%$$ FG^0_2 = \{C_1, C_3, K_4\},$$
%%$$ FG^0_3 = \{C_5, C_6, K_7\}.$$
$$ fm(FG^0_1) = \{C_{1 a}, C_{1 b}, C_{2 a}, C_{2 b}\},$$
$$ fm(FG^0_2) = \{C_{1 a}, C_{1 b}, C_{2 a}, C_{2 b}, K_{4 a}, K_{4 b}, K_{4 d}\},$$
$$ fm(FG^0_3) = \{C_{5 a}, C_{5 b}, C_{6 a}, C_{6 b}, K_{7 a}, K_{7 b}, K_{7 d}\}.$$
The next stage is to look at the failure modes from the perspective of
the functional groups, rather than the components.
We can call these failures modes `symptoms'.
As this is a theoretical example, we shall have to skip this step.
The next stage is to collect the common symptoms, or the symtoms that
are the same {\em from the perspective of a user of the {\fg}}.
We can define this stage as the function $\bowtie$ which has a set of failure modes as
its range and {\dc} as its domain.
For the sake of example let us determine some arbitary collections
into symptoms. Let us group the symptoms from $ FG^0_1 $ as the following
$ s1 = \{ C_{1 a}, C_{2 b} \}$ and $ s2 = \{ C_{1 b}, C_{2 a} \}$.
We can now create a new {\dc}. This will have an $\alpha$ value higher
than the {\fg} it was derived from.
thus
$$ DC^1_1 = \bowtie fm(FG^0_1) .$$
Applying $fm$ to our new derived component will give us our symptoms from functional group $ FG^0_1 $
thus
$$ fm(DC^1_1) = \{s1, s2 \}.$$
UML OBJECT MODEL OF DERIVED COMPONENT TOO

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@ -32,7 +32,7 @@
\author{R.P.Clark}
\title{FMMD Data Model}
\maketitle
\input{fmmd_data_model}
\input{fmmd_data_model_paper}
\bibliographystyle{plain}
\bibliography{../vmgbibliography,../mybib}

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@ -66,7 +66,7 @@
%\newcommand{\wlc}{{Water~Level~Controller~Unit}}
%\newcommand{\ft}{{\em 4 $\rightarrow$ 20mA } }
%\newcommand{\tds}{TDS Daughterboard}
\newcommand{\oc}{$^{o}{C}$}
\newcommand{\oc}{\ensuremath{^{o}{C}}}
\newcommand{\adctw}{{${\mathcal{ADC}}_{12}$}}
\newcommand{\adcten}{{${\mathcal{ADC}}_{10}$}}
\newcommand{\ohms}[1]{\ensuremath{#1\Omega}}