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Robin Clark 2013-02-08 18:11:57 +00:00
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21
mybib.bib
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@ -27,6 +27,27 @@
@TechReport{modbus,
author = {MODBUS.ORG},
title = {MODBUS over serial line: Specification and implementation guide V1.0},
institution = {MODBUS.ORG},
year = {2002},
key = {},
OPTtype = {},
OPTnumber = {},
OPTaddress = {},
OPTmonth = {},
OPTnote = {},
OPTannote = {},
OPTurl = {},
OPTdoi = {},
issn = {V1.0},
OPTlocalfile = {},
OPTabstract = {},
}
@INPROCEEDINGS{5488118,
author={Pace, C. and Libertino, S. and Crupi, I. and Marino, A. and Lombardo, S. and Sala, E.D. and Capuano, G. and Lisiansky, M. and Roizin, Y.},
booktitle={Instrumentation and Measurement Technology Conference (I2MTC), 2010 IEEE}, title={Compact instrumentation for radiation tolerance test of flash memories in space environment},

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submission_thesis/CH3_FMEA_criticism/copy.tex
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@ -2,24 +2,34 @@
\section{Historical Origins of FMEA}
\subsection{FMEA designed for simple electro-mechanical systems}
So its old and prob out of date
FMEA traces it roots to the 1940s when it was used to identify the most costly
failures arising from car mass-production~\cite{pfmea}.
It was later modified slightly to include severity of the top level failure (FMECA~\cite{fmeca}).
In the 1980s FMEA was extended again (FMEDA~\cite{fmeda}) to provide statistics
for predicting failure rates.
However a typical entry in each of the above methodologies, starts with a
particular component failure mode and associates it with a system---or top level---failure symptom.
This analysis philosophy has not changed since FMEA was first used.
\subsection{FMEA does not support modularity.}
It is a common practise in industry to buy in sub-systems, especially sensors.
Most sensor systems now are `smart', that is to say, they contain programatic elemnts
even if they supply analog signals. For instance a liquid level sensor that
It is a common practise in the process control industry to buy in sub-systems, typically sensors and actuators connected to an industrially hardened computer bus, i.e. CANbus~\cite{can,canspec}, modbus~\cite{modbus} etc.
Most sensor systems now are `smart', that is to say, they contain programmatic elements
even if their outputs are %they supply
analogue signals. For instance a liquid level sensor that
supplies a {\ft} output, would have been typically have been implemented
in analog electronics before the 1980s. After that time, it would be common to use a micro-processor
in analogue electronics before the 1980s. After that time, it would be common to use a micro-processor
based system to perform the functions of reading the sensor and converting it to a current (\ft) output.
For the non-safety critical systems integrator this brings with it the advantages
that come with using a digital system (increased accuracy, self checking and ease of
calibration etc). For a safety critical systems integrator this can be very problematic when it
calibration etc. ). For a safety critical systems integrator this can be very problematic when it
comes to approvals. Even if the sensor manufacturer will let you see the internal workings and software
we have a problem with tracing the FMEA reasoning through the sensor, through the sensors software
and then though the system being integrated.
This problem is compounded by the fact that traditional FMEA cannot integrate software into FMEA models~\cite{sfmea,safeware}.
\section{Reasoning Distance}
\section{Comparison Complexity}
\section{Reasoning Distance used to measure Comparison Complexity}
@ -44,7 +54,7 @@ This problem is compounded by the fact that traditional FMEA cannot integrate so
\subsection{FMEA - Better Methodology - Wish List}
\subsection{FMEA - Better Metodology - Wish List}
\subsection{FMEA - Better Methodology - Wish List}
\begin{itemize}

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submission_thesis/CH6_Evaluation/copy.tex
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@ -173,9 +173,11 @@ state $$ \forall FG \in \mathcal{FG} | FG \subset \mathcal{G} .$$
FMMD analysis creates a hierarchy $H$ of {\fgs} where $H \subset \mathcal{FG}$.
%
We can define individual {\fgs} using $FG$ with an index to identify them and a superscript
to identify the hierarchy level. For instance the first {\fg} in a hierarchy, containing base components only
i.e. at the zeroth level of an FMMD hierarchy, would have the superscript 0 and a subscript of 1, i.e. $FG^{0}_{1}$.
We can define individual {\fgs} using $FG^{\alpha}_{i}$ with an index, $i$ for identification and a superscript for the $\alpha$~level (see section~\ref{sec:alpha}).
%---
%o identify the hierarchy.
For instance the first {\fg} in a hierarchy, containing base components only
i.e. at the zeroth level of an FMMD hierarchy where $\alpha=0$, would have the superscript 0 and a subscript of 1: $FG^{0}_{1}$.
%$$
%Equation~\ref{eqn:rd} can also be expressed as
%