From 74b160a9276d7c32afa446227dc835f81d1f2f63 Mon Sep 17 00:00:00 2001 From: Robin Clark Date: Fri, 7 Jan 2011 09:39:25 +0000 Subject: [PATCH] . --- fmmd_concept/fmmd_concept.tex | 9 +++++---- fmmd_design_aide/fmmd_design_aide.tex | 8 ++++---- sw_as_plds/sw_as_plds.tex | 10 +++++++--- 3 files changed, 16 insertions(+), 11 deletions(-) diff --git a/fmmd_concept/fmmd_concept.tex b/fmmd_concept/fmmd_concept.tex index 2cd8c16..454d20d 100644 --- a/fmmd_concept/fmmd_concept.tex +++ b/fmmd_concept/fmmd_concept.tex @@ -1200,12 +1200,13 @@ chosing {\fg}s and working bottom-up this hierarchical trait will occur as a nat \item It is possible to model multiple failure modes. \end{itemize} -\section{Re-Factoring the UML Model} -The UML models thus far in this \ifthenelse {\boolean{paper}} { %paper +\pagebreak[4] +\section{Re-Factoring the UML Model} +The UML models thus far in this have been used to develop the data relationships required to perform FMMD analysis. This section re-organises and rationalises the UML model. We want to be able to use {\dcs} in functional groups. @@ -1225,6 +1226,7 @@ The re-factored UML diagram is shown in figure \ref{fig:refactored_uml}. } { % chapter +\section{Re-Factoring the UML Model} The terms used in FMMD and the UML data model are refined in the chapter \ref{defs}. } @@ -1243,5 +1245,4 @@ provides the background for the need for a new methodology for static analysis that can span the mechanical electrical and software domains using a common notation. The author believes it addresses many short comings in current static failure mode analysis methodologies. -\vspace{60pt} -\today +%\today diff --git a/fmmd_design_aide/fmmd_design_aide.tex b/fmmd_design_aide/fmmd_design_aide.tex index 82eda62..613d193 100644 --- a/fmmd_design_aide/fmmd_design_aide.tex +++ b/fmmd_design_aide/fmmd_design_aide.tex @@ -77,7 +77,7 @@ The `undetectable' failure modes undertsandably, are the most worrying for the s EN61058, the statistically based European Norm, using ratios of detected and undetected system failure modes to classify the sytems safety levels and describes sub-clasifications -for detected and undetected failure modes \cite{en61508}. +for detected and undetected failure modes~\cite{en61508}. %It is these that are, generally the ones that stand out as single %failure modes. @@ -231,7 +231,7 @@ and this error symptom, `low\_reading' would mean our plant could beleive that the temperature reading is lower than it actually is. To take an example from a K type thermocouple, the offset of 1.86mV %from the potential divider represents amplified to -would represent $\approx \; 46\,^{\circ}{\rm C}$ \cite{eurothermtables} \cite{aoe}. +would represent $\approx \; 46\,^{\circ}{\rm C}$~\cite{eurothermtables}~\cite{aoe}. %\clearpage \subsection{Undetected Failure Mode: Incorrect Reading} @@ -500,7 +500,7 @@ We can surmise the symptoms in a list. %\clearpage \subsection{OP-AMP FIT Calculations} The DOD electronic reliability of components -document MIL-HDBK-217F\cite{mil1992}[5.1] gives formulae for calculating +document MIL-HDBK-217F~\cite{mil1991}[5.1] gives formulae for calculating the %$\frac{failures}{{10}^6}$ ${failures}/{{10}^6}$ % looks better @@ -553,7 +553,7 @@ failures per Billion (${10}^9$) hours of operation} of 1. The switching transistor will be operating at a low frequency and well within 50\% of it maximum voltage. -MIL-HDBK-217F\cite{mil1992}[6-25] gives an exmaple +MIL-HDBK-217F~\cite{mil1991}[6-25] gives an exmaple transistor in these environmental conditions, and assigns an FIT value of 11. \section{Conclusions} diff --git a/sw_as_plds/sw_as_plds.tex b/sw_as_plds/sw_as_plds.tex index 57ed172..7c1f6f8 100644 --- a/sw_as_plds/sw_as_plds.tex +++ b/sw_as_plds/sw_as_plds.tex @@ -42,11 +42,15 @@ Transitioning between one stage and another depends on decisions made from variable states. This corresponds to the standard software structures, if-then-else do-while etc. -At a program flow stage, the software may initiate actions. Typically, in an embedded -system, a micro controller will read from external sensors, and then apply +Generally the flow of data follows a pattern of afferent, transform and efferent. +That is to say data is input, processed and data is output. + +%At a program flow stage, the software may initiate actions. +In a safety critical control system +typically, an embedded +electro-mechanical system, a micro controller will read from external sensors, and then apply outputs to control the equipment under supervision. -More generally the flow of data follows a pattern of afferent, transform and efferent. \subsection{Afferent, Transform and Afferent Data Flow}