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@ -1200,12 +1200,13 @@ chosing {\fg}s and working bottom-up this hierarchical trait will occur as a nat
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\item It is possible to model multiple failure modes.
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\end{itemize}
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\section{Re-Factoring the UML Model}
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The UML models thus far in this
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\ifthenelse {\boolean{paper}}
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{
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%paper
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\pagebreak[4]
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\section{Re-Factoring the UML Model}
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The UML models thus far in this
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have been used to develop the data relationships required to perform FMMD analysis.
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This section re-organises and rationalises the UML model.
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We want to be able to use {\dcs} in functional groups.
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@ -1225,6 +1226,7 @@ The re-factored UML diagram is shown in figure \ref{fig:refactored_uml}.
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}
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{
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% chapter
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\section{Re-Factoring the UML Model}
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The terms used in FMMD and the UML data model are refined in the
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chapter \ref{defs}.
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}
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@ -1243,5 +1245,4 @@ provides the background for the need for a new methodology for
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static analysis that can span the mechanical electrical and software domains
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using a common notation.
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The author believes it addresses many short comings in current static failure mode analysis methodologies.
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\vspace{60pt}
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\today
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%\today
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@ -77,7 +77,7 @@ The `undetectable' failure modes undertsandably, are the most worrying for the s
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EN61058, the statistically based European Norm, using ratios
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of detected and undetected system failure modes to
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classify the sytems safety levels and describes sub-clasifications
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for detected and undetected failure modes \cite{en61508}.
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for detected and undetected failure modes~\cite{en61508}.
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%It is these that are, generally the ones that stand out as single
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%failure modes.
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@ -231,7 +231,7 @@ and this error symptom, `low\_reading' would mean our plant could
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beleive that the temperature reading is lower than it actually is.
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To take an example from a K type thermocouple, the offset of 1.86mV
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%from the potential divider represents amplified to
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would represent $\approx \; 46\,^{\circ}{\rm C}$ \cite{eurothermtables} \cite{aoe}.
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would represent $\approx \; 46\,^{\circ}{\rm C}$~\cite{eurothermtables}~\cite{aoe}.
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%\clearpage
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\subsection{Undetected Failure Mode: Incorrect Reading}
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@ -500,7 +500,7 @@ We can surmise the symptoms in a list.
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%\clearpage
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\subsection{OP-AMP FIT Calculations}
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The DOD electronic reliability of components
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document MIL-HDBK-217F\cite{mil1992}[5.1] gives formulae for calculating
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document MIL-HDBK-217F~\cite{mil1991}[5.1] gives formulae for calculating
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the
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%$\frac{failures}{{10}^6}$
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${failures}/{{10}^6}$ % looks better
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@ -553,7 +553,7 @@ failures per Billion (${10}^9$) hours of operation} of 1.
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The switching transistor will be operating at a low frequency
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and well within 50\% of it maximum voltage.
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MIL-HDBK-217F\cite{mil1992}[6-25] gives an exmaple
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MIL-HDBK-217F~\cite{mil1991}[6-25] gives an exmaple
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transistor in these environmental conditions, and assigns an FIT value of 11.
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\section{Conclusions}
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@ -42,11 +42,15 @@ Transitioning between one stage and another depends on decisions made from
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variable states. This corresponds to the standard software structures, if-then-else
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do-while etc.
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At a program flow stage, the software may initiate actions. Typically, in an embedded
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system, a micro controller will read from external sensors, and then apply
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Generally the flow of data follows a pattern of afferent, transform and efferent.
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That is to say data is input, processed and data is output.
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%At a program flow stage, the software may initiate actions.
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In a safety critical control system
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typically, an embedded
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electro-mechanical system, a micro controller will read from external sensors, and then apply
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outputs to control the equipment under supervision.
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More generally the flow of data follows a pattern of afferent, transform and efferent.
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\subsection{Afferent, Transform and Afferent Data Flow}
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