From 9c21afaffdac838ded80d94337e5fc2096821591 Mon Sep 17 00:00:00 2001 From: "Robin P. Clark" Date: Mon, 4 Feb 2013 09:51:21 +0000 Subject: [PATCH] CH3 changes were not commited. modbus ref added to mybib.bib --- mybib.bib | 21 ++++++++++++++ submission_thesis/CH3_FMEA_criticism/copy.tex | 28 +++++++++++++------ 2 files changed, 40 insertions(+), 9 deletions(-) diff --git a/mybib.bib b/mybib.bib index 29b5aa8..1eaf93e 100644 --- a/mybib.bib +++ b/mybib.bib @@ -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}, diff --git a/submission_thesis/CH3_FMEA_criticism/copy.tex b/submission_thesis/CH3_FMEA_criticism/copy.tex index 885180b..478e72e 100644 --- a/submission_thesis/CH3_FMEA_criticism/copy.tex +++ b/submission_thesis/CH3_FMEA_criticism/copy.tex @@ -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Origins of FMEA} \subsection{FMEA designed for simple electro-mechanical systems} -So its old and prob out of date +FMEA traces it roots to the 1940s when it was used to identify the most costly +failures arising from car mass-production~\cite{pfmea}.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}