final fiddling around. This is as was sent for the second CH4
review. This time Andrew might look at it.
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@BOOK{dmfnt,
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AUTHOR = "R Garnier, J Taylor",
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TITLE = "Discrte Mathematics for New Technology ISBN 0-7503-0135-X",
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TITLE = "Discrete Mathematics for New Technology ISBN 0-7503-0135-X",
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PUBLISHER = "IoP",
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YEAR = "1992"
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}
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@ -51,23 +51,19 @@ to build higher level groups.
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\section{Introduction}
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This
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\ifthenelse {\boolean{paper}}
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{
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paper
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}
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{
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chapter
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}
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starts with a worked example using the new methodology, Failure Mode Modular De-composition (FMMD).
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This chapter
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starts with an overview of current failure modelling techniques, and then worked example using the new methodology,
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Failure Mode Modular De-composition (FMMD).
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This is followed by a discussion on the design of the FMMD methodology and then
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an ontological description is given using UML class models.
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A notation is then described to index and classify objects created in FMMD hierarchical models.
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\subsection{Overview of current failure mode modelling techniques}
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We briefly analyse four current methodologies.
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Comprehensive overviews of these methodologies may be found
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in ~\cite{safeware,sccs}.
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in ~\cite{safeware,sccs,nasafta,nucfta,bfmea}.
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\paragraph{Fault Tree Analysis (FTA).}
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FTA~\cite{nasafta,nucfta} is a top down methodology in which a hierarchical diagram is drawn for
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@ -1030,7 +1026,7 @@ The symptoms of failure of the {\fg} are the failure modes of this new `derived
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%1991 reliability manual\cite{mil1991} applies a FIT of 100 for this generic type of component}
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Electrical components have detailed data-sheets associated with them. A useful extension of this could
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be failure modes of the component, with environmental factors and MTTF statistics.
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be failure modes of the component, with environmental factors and MTTF~\cite{sccs}[p.165] statistics.
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Currently this sort of failure mode information is generally only available for generic component types \cite{mil1991}.
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\begin{table}[h]
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@ -1573,8 +1569,8 @@ failure modes being the failure symptoms of the {\fg} from which it was derived.
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%where its failure modes, are the symptoms from {\fg}.
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%
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Note that the {\dc} must have a higher abstraction level than the {\fg}
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from which it was derived---or---in other words, the symptom abstraction process `$\derivedc$' increments
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the abstraction level $abslev$, as stated in equation~\ref{eqn:abslevinc}.
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from which it was derived---or---in other words, the symptom abstraction process `$\derivec$' increments
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the abstraction level $\abslev$, as stated in equation~\ref{eqn:abslevinc}.
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The symptom abstraction process is described formally and algorithmically
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in sections~\ref{sec:formalfmmd} and \ref{sec:algorithmfmmd} respectively.
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@ -1845,9 +1841,13 @@ component level failure modes.
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This allows cut sets~\cite{nasafta}[Ch.1p3]
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to be determined by traversing the DAG from top level events down to their causes.
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%
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This has the added advantage of each {\fg} to {\dc} stage being a documented
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failure mode reasoning entity. Compare this to traditional FMEA where
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we only have one stage, base component failure mode to top level event.
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An added advantage of FMMD, is that there are typically several stages of reasoning
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to go from a base component failure mode to a system/top level event.
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%
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Each of these reasoning stages are represented by {\fg} to {\dc} analysis processes, traversing up the FMMD hierarchy.
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%
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Compare this to traditional FMEA where
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we only have one reasoning stage, that of base component failure mode to top level event.
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% \item{ It should be capable of producing reliability and danger evaluation statistics.}
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% The minimal cuts sets for the system level failures can have computed MTTF
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@ -1889,7 +1889,7 @@ An example demonstrating multiple failure mode analysis may be found in section~
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{ %\tiny
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\begin{table}[ht]
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\caption{Features of static Failure Mode analysis methodologies} % title of Table
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%\centering % used for centering table
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\centering % used for centering table
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\begin{tabular}{||l|c|c|c|c|c||}
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\hline \hline
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% \textbf{Des.} & \textbf{FTA} & \textbf{FMEA} & \textbf{FMECA} & \textbf{FDEMA} & \textbf{FMMD} \\
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\subsection{Determining the failure modes of components}
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\label{sec:determine_fms}
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In order to apply any form of Failure Mode Effects Analysis (FMEA) we need to know the ways in which the components we are using can fail.
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A good introduction to hardware and software failure modes may be found in~\cite{sccs}[pp.114-124].
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Typically when choosing components for a design, we look at manufacturers' data sheets,
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which describe the environmental ranges and tolerances, and can indicate how a component may fail/behave
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under certain conditions or environments.
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@ -12,6 +12,7 @@ clean:
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rm ${CHAPTERS}
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bib:
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pdflatex thesis # do this first otherwise bibtex gets its knickers in a twist
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bibtex thesis
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chapters_sub_make:
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