tidying up metrics chapter....

submission_thesis/CH1_introduction/copy.tex

@@ -1,3 +1,4 @@
+\label{sec:chap1}
 
 %\paragraph{Abstract} % : The Scope of this study.}{
 {

submission_thesis/CH3_FMEA_criticism/copy.tex

@@ -2,7 +2,22 @@
 
 \section{Historical Origins of FMEA}
 \subsection{FMEA designed for simple electro-mechanical systems}
+So its old and prob out of date
 
+\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
+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
+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
+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}
 

submission_thesis/CH6_Evaluation/copy.tex

@@ -3,6 +3,25 @@
 \section*{Metrics}
 
 
+%
+It begins be defining a metric for  the complexity of an FMEA analysis task.
+%
+This  concept is called `comparisson~complexity' and is a means to assess FMMD against current FMEA methodologies. 
+%
+This metric is developed formally and then formulae are presented for comparing the 
+complexity of using  modularised or straightforward FMEA.
+%
+These formulae are then used for a hypothetical example, analysed by FMEA and FMMD.
+ 
+FMMD makes the claim that it can perform double simultaneous failure mode analysis without an undue
+state explosion drawback.
+To back this up, an example of double failure analysis is provided, using single and double
+failure analysis, using the four wire Pt100
+temperature measurement sensor circuit. This example is also used to show how component failure rate statistics can be 
+used with FMMD.
+
+This is followed by some critiques i.e. possible areas of difficulty when performing FMMD, and then 
+a general evaluation. % comparing it with traditional FMEA.
 
 %
 % Moving Pt100 to metrics
@@ -19,7 +38,9 @@
 % DOMAIN == INPUTS
 % RANGE == OUTPUTS
 %
-
+When we hear of a safety critical system we typically think of it in terms of
+the physical plant---or in terms of its safety functionality.
+%
 When performing FMEA we consider the system under investigation
 to be a collection of components which have associated failure modes.
 %
@@ -28,8 +49,8 @@ We apply reasoning  to calculate, using the failure modes, the effects
 %from these failure modes (the causes, {\fms} of {\bcs}) to the effects
 (or symptoms of failure) at the top level.
 %
-We can view FMEA as a process, taking each component in the system and for all its failure modes 
+We can view FMEA as a process, taking each component in the system and for each of its failure modes 
-applying analysis.
+applying analysis with respect to the whole system.
 %
 This however entails a problem: which other components in the system must we
 check against the %current failure mode.
@@ -64,13 +85,16 @@ against all the components in the system.
 This would mean we would be looking for all possible side effects that a base component failure could cause.
 %
 We could term this `rigorous~FMEA'~(RFMEA).
-The number of checks we have to make to achieve this, gives an indication of the complexity of the task.
+The number of checks we have to make to achieve this, gives an indication of the complexity of the analysis task.
-This is described in section~\ref{sec:rd}, where the reasoning distance, or complexity to
+%
-analyse a single FMEA failure scenario, is given in equation~\ref{eqn:complexity}.
+%This is described in section~\ref{sec:rd}, where the reasoning distance, or complexity to
+%analyse a single FMEA failure scenario, is given in equation~\ref{eqn:complexity}.
 %
 %
-We term this `comparison~complexity', the number of 
+It is desirable to be able to measure the complexity of an analysis task.
-paths between failure modes and components necessary to achieve RFMEA for a given system/{\fg}.
+%
+We term this `comparison~complexity', count the number of 
+paths between failure modes and components necessary to achieve RFMEA for a given system or {\fg}.
 
 % (except its self of course, that component is already considered to be in a failed state!).
 %