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@ -292,9 +292,10 @@ would have an $\alpha$ value of 1.
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Let the set of all possible components be $\mathcal{C}$
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and let the set of all possible failure modes be $\mathcal{F}$ and $\mathcal{PF}$ is the powerset of
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all $\mathcal{F}$..
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all $\mathcal{F}$.
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We can define a function $fm$ as equation \ref{eqn:fmset}.
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\label{fmdef}
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\begin{equation}
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fm : \mathcal{C} \rightarrow \mathcal{P}\mathcal{F}
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@ -763,6 +764,7 @@ operational states.
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The additional objects System, Environment and Operational States
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are added to UML diagram in figure \ref{fig:cfg} and represented in figure \ref{fig:cfg2}.
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\label{completeuml}
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\begin{figure}[h]
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\centering
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@ -8,31 +8,53 @@
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%% What I have done
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%%
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This paper presents a simple two stage Failure Mode Modular De-Composition (FMMD)
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model of a theoretical System.
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The Analysis model is then represented as a Directed Acyclic Graph (DAG), of the {\fg}s
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components and failure modes represented in it.
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%% What I have found
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% What I have found
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%%
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From traversing the DAG, minimal cut sets (component level combinations
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that cause system level failures) are revealed.
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Common mode failure modes and same component dependencies
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can also be automatically determined.
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%% Sell it
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%%
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}
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}
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By having a clear data model, we can not only produce results
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for the traditional methodologies, we can trace common mode and
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component dependency failures as well.
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Also, with statistical data, we can use the minimal cut set results
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to determine the likelihood of particular system failures, even
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if they have multiple causes.
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} % abstract
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} % ifthenelse
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{
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%%% CHAPTER INTO NEARLT THE SAME AS ABSTRACT
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\section{Introduction}
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This chapter
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presents a simple two stage FMMD % Failure Mode Modular De-Composition (FMMD)
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model of a theoretical System.
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The Analysis model is then represented as a Directed Acyclic Graph (DAG), of the {\fg}s
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components and failure modes represented in it.
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%% What I have done
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% What I have found
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%%
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%% What I have found
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%%
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%and considering some constraints determined from
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%the evaluation of the four established methodologies,
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From traversing the DAG, minimal cut sets (component level combinations
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that cause system level failures) are revealed.
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Common mode failure modes and same component dependencies
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can also be automatically determined.
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%% Sell it
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%%
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By having a clear data model, we can not only produce results
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for the traditional methodologies, we can trace common mode and
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component dependency failures as well.
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Also, with statistical data, we can use the minimal cut set results
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to determine the likelihood of particular system failures, even
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if they have multiple causes.
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}
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%{ \huge This might become a chapter in its own right after fmmdset }
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@ -60,7 +82,7 @@ represents the FMMD hierarchy level, or $\alpha$ value, thus:
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}
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{
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We can organise these into functional groups (where the superscript
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represents the $\alpha$ value, see section \ref{alpha}), thus:
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represents the $\alpha$ value, or FMMD hierarchy level, see section \ref{alpha}), thus:
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}
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$$ FG^0_1 = \{C_1, C_2\},$$
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@ -68,10 +90,28 @@ $$ FG^0_2 = \{C_1, C_3, K_4\},$$
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$$ FG^0_3 = \{C_5, C_6, K_7\}.$$
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Note that in this model the base~component $C_1$ has been used in
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two separate functional groups.
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two separate functional groups. This could be a component that they
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both commonly use. A real world example of a component included in
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more than one {\fg} could
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be a powersupply or DCDC\footnote{A DCDC (direct current to direct current)
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converter, is a common feature in modern PCBs, used to provide isolation
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and/or voltage supplies at a different EMF from the source of power.}
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converter shared to power
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the functional groups $FG^0_1$ and $FG^1_1$.
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Also that the component type $K$ has been used by
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two different functional groups.
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For the sake of example let our temperature environment
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for the SYSTEM be ${{0}\oc}$ to ${{125}\oc}$, but let the component
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type `K' have a de-graded performance failure mode between
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${{80}\oc}$ and ${{125}\oc}$\footnote{ A real world example of
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degraded performace with temperature is the isolating opto coupler.
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These can typically only cope with lower baud rate ranges
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at high temperatures \cite{tlp181}.}. We can term this
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degraded performce of component `K' as failure mode `d'.
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\paragraph{Symptom Extraction.}
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A processes of symptom extraction is now applied to the functional groups.
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Again for the sake of example, let us say that each functional
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@ -81,6 +121,83 @@ Applying symptom abstraction to $FG^0_1$ i.e. $\bowtie fm ( FG^0_1 ) = \{ FG^0_{
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We can now create a new derived component, $DC^1_1$, whose failure
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modes are the symptoms of $FG^0_1 $ thus $ fm ( {DC}^1_1 ) = \{ FG^0_{1 a}, FG^0_{1 b} \} $.
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\paragraph{Building the Object Model}
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Using the UML model in figure \ref{fig:cfg2fmmd_data} we will apply FMMD analysis stages
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to build a hierarchy representing the whole system, begining with the $FG^0$ level functional groups.
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\begin{figure}[h]
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\centering
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\includegraphics[width=400pt,bb=0 0 702 464,keepaspectratio=true]{./fmmd_data_model/cfg2.jpg}
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% cfg2.jpg: 702x464 pixel, 72dpi, 24.76x16.37 cm, bb=0 0 702 464
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\caption{UML Class model for FMMD}
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\label{fig:cfg2fmmd_data}
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\end{figure}
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% %\begin{figure}[h]
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% \centering
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% \includegraphics[width=400pt,keepaspectratio=true]{./fmmd_data_model/cfg2.jpg}
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% % cfg2.jpg: 702x464 pixel, 72dpi, 24.76x16.37 cm, bb=0 0 702 464
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% \caption{Complete UML diagram}
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% \label{fig:cfg2fmmd_data}
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% \end{figure}
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\paragraph{Find Failure Modes}
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Consider the SYSTEM environment with its temperature range of ${{0}\oc}$ to ${{125}\oc}$.
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We must check this against all components used.
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For our example, we component `K' which has an extra
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failure mode for degraded performance `d'.
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\ifthenelse {\boolean{paper}}
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{
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We can definine a `failure modes' function $fm$ that has a functional group as its range
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and returns a set of failure modes as its domain.
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We now use this to determine the failure modes
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in our functional groups.
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}
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{
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Using the overloaded function $fm$ from chapter \ref{fmdef} we can determine the failure modes
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in our functional groups.
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}
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Applying the function $fm$ to our functional groups, with the SYSTEM environmental
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constraint applied to component type `K', yields
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%%//$$ FG^0_1 = \{C_1, C_2\},$$
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%%$$ FG^0_2 = \{C_1, C_3, K_4\},$$
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%%$$ FG^0_3 = \{C_5, C_6, K_7\}.$$
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$$ fm(FG^0_1) = \{C_{1 a}, C_{1 b}, C_{2 a}, C_{2 b}\},$$
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$$ fm(FG^0_2) = \{C_{1 a}, C_{1 b}, C_{2 a}, C_{2 b}, K_{4 a}, K_{4 b}, K_{4 d}\},$$
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$$ fm(FG^0_3) = \{C_{5 a}, C_{5 b}, C_{6 a}, C_{6 b}, K_{7 a}, K_{7 b}, K_{7 d}\}.$$
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The next stage is to look at the failure modes from the perspective of
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the functional groups, rather than the components.
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We can call these failures modes `symptoms'.
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As this is a theoretical example, we shall have to skip this step.
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The next stage is to collect the common symptoms, or the symtoms that
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are the same {\em from the perspective of a user of the {\fg}}.
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We can define this stage as the function $\bowtie$ which has a set of failure modes as
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its range and {\dc} as its domain.
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For the sake of example let us determine some arbitary collections
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into symptoms. Let us group the symptoms from $ FG^0_1 $ as the following
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$ s1 = \{ C_{1 a}, C_{2 b} \}$ and $ s2 = \{ C_{1 b}, C_{2 a} \}$.
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We can now create a new {\dc}. This will have an $\alpha$ value higher
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than the {\fg} it was derived from.
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thus
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$$ DC^1_1 = \bowtie fm(FG^0_1) .$$
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Applying $fm$ to our new derived component will give us our symptoms from functional group $ FG^0_1 $
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thus
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$$ fm(DC^1_1) = \{s1, s2 \}.$$
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UML OBJECT MODEL OF DERIVED COMPONENT TOO
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\author{R.P.Clark}
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\title{FMMD Data Model}
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\maketitle
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\input{fmmd_data_model}
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\input{fmmd_data_model_paper}
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\bibliographystyle{plain}
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\bibliography{../vmgbibliography,../mybib}
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%\newcommand{\wlc}{{Water~Level~Controller~Unit}}
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%\newcommand{\ft}{{\em 4 $\rightarrow$ 20mA } }
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%\newcommand{\tds}{TDS Daughterboard}
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\newcommand{\oc}{$^{o}{C}$}
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\newcommand{\oc}{\ensuremath{^{o}{C}}}
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\newcommand{\adctw}{{${\mathcal{ADC}}_{12}$}}
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\newcommand{\adcten}{{${\mathcal{ADC}}_{10}$}}
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\newcommand{\ohms}[1]{\ensuremath{#1\Omega}}
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