better refs, 2 weeks in no C2H5O.
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% my bib file.
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@ARTICLE{fmd91,
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AUTHOR = "Reliability Analysis Center",
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TITLE = "Failure Mode/Mechanisms Distributions 1991",
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JOURNAL = "United States Department of Commerce",
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YEAR = "1991"
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}
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% $Id: mybib.bib,v 1.3 2009/11/28 20:05:52 robin Exp $
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@article{Clark200519,
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@ -156,7 +156,7 @@ for the effects of component failures.
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All components have a set of known `failure modes'.
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In other words we know that a given component can fail in several distinct ways.
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Studies have been published which list common component types
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and their sets of failure modes, often with MTTF statistics \cite{mil1991}.
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and their sets of failure modes~\cite{fmd91}, often with MTTF statistics~\cite{mil1991}.
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Thus for each component, an analysis is made for each of its failure modes,
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with respect to its effect on the
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circuit. Each one of these scenarios is termed a `test case'.
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@ -170,9 +170,10 @@ Where this occurs a circuit re-design is probably the only sensible course of ac
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\subsection{Single Fault FMEA Analysis \\ of PT100 Four wire circuit}
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\label{fmea}
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This circuit simply consists of three resistors.
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Resistors according to the DOD Electronic component fault handbook
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1991, fail by either going OPEN or SHORT circuit \cite{mil1991}.
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The PT100 circuit consists of three resistors, two `current~supply'
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wires and two `sensor' wires.
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Resistors according to the European Standard EN298:2003~\cite{en298}[App.A]
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, are considered to fail by either going OPEN or SHORT circuit.
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%Should wires become disconnected these will have the same effect as
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%given resistors going open.
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For the purpose of this analyis;
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@ -104,10 +104,10 @@ failsafes meant that the objective was to iron out common failures
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not to rigorously detect all possible failures.
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Consequently it was not designed to guarantee to covering all component failure modes,
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and has no rigorous in-built safeguards to ensure coverage of all possible
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system level outcomes.
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system level outcomes~\cite{nasafta}[Section 1.2].
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FTA, like all top~down methodologies introduces the very serious problem
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of missing component failure modes \cite{faa}[Ch.9].
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of missing component failure modes~\cite{faa}[Ch.9].
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\paragraph{Outline of FTA Methodology}
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FTA works by taking an undesireable event
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@ -277,7 +277,7 @@ FMEA described in this section (\ref{pfmea}) is sometimes called `production FME
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\subsection{FMECA}
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Failure mode, effects, and criticality analysis (FMECA)~\cite{FMD-91} extends FMEA
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Failure mode, effects, and criticality analysis (FMECA)~\cite{fmd91} extends FMEA
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by associaing failure probabilities with component failure modes.
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Essentially this adds a failure outcome criticallity factor to FMEA.
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This is a bottom up methodology, which builds on an existing FMEA
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@ -326,7 +326,7 @@ this can be the number of operating cycles or demands expected.
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\paragraph{Severity `s' value}
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Component failure modes can cause failures that have levels of severity or seriousness.
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Typical classifications are as follows:~\cite{FMD-91}
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Typical classifications are as follows:~\cite{fmd91}
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\begin{itemize}
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\item Category I - Catastrophic
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\item Category II - Critical
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@ -364,7 +364,7 @@ $s$ thus:
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%%-WIKI- FMECA tends to be preferred over FMEA in space and North Atlantic Treaty Organization (NATO) military applications,
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%%-WIKI- while various forms of FMEA predominate in other industries.
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A second result, representing the overall reliability and safety of a component or item\cite{FMD-91}[2-17] $C$,
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A second result, representing the overall reliability and safety of a component or item~\cite{fmd91}[2-17] $C$,
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termed a criticallity number $C_r$ for the component.
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We can consider $C$ to be a flat set of component failure modes, using $cfm$ as a variable to represent them.
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% where $f \in F$)
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