Notes and skeleton chapters.

old_thesis/component_failure_modes_definition/component_failure_modes_definition.tex

@@ -86,7 +86,7 @@ defines a `part' thus
 The term component, in American English, can mean a building block or a part.
 In British-English a component generally is given to mean the definition for part above.
 For this study, we will use {\bc} to mean a `part', and component
-to mean a part or sub-assembly. 
+to mean a part or a sub-assembly. 
 
 What components all have in common is that they can fail, and fail in
 a number of well defined ways. For common base-components
@@ -146,9 +146,9 @@ When building from the bottom up, it is more meaningful to call them `derived~co
 
 \section{Failure Modes in depth: A detailed look at the op-amp and the resistor}
 
-We look in detail at two common electrication components in this section and examine how
+We look in detail at two common electrical components in this section and examine how
 two sources of information on failure modes view their failure mode behaviour.
-We look at the reasons why some known failure modes are ommitted, or presented in 
+We look at the reasons why some known failure modes are omitted, or presented in 
 specific but unintuitive ways.
 
 - Failure modes. Prescribed failure modes EN298 - FMD91
@@ -156,14 +156,28 @@ specific but unintuitive ways.
 \subsection{resistor}
 
 EN298 says......
-Parameter change not considereed for EN298 because the resistors are downrated from
+Parameter change not considered for EN298 because the resistors are down-rated from
 maximum possible voltage exposure -- find refs.
 
+
+FMD-91 gives the following percentatges for failure rates in
+\label{downrate}
+The parameter change, is usually a failure mode associated with over stressing the component.
+In a system designed to typical safety critical constraints (as in EN298)
+these environmentally induced failure modes need not be considered.
+
 \subsection{op-amp}
 
 Literature suggests, latch up, latch down and oscillation.
 FMD-91 states, V+ disconnected, V- V+ shorted, NOOP and Low slew.
 
+EN298 does not specifgically include OP_AMPS and these would fall under
+table \cite{en298}[A.1 note e].
+This demands that all open connections, and shorts between adjacent pins be considered.
+We can examine these failure modes by taking our 358 op-amp and examining
+
+
+ looking at
 Discuss why. Determine more user friendly terms from FMD91 definition.
 
 
@@ -887,6 +901,9 @@ levels of electrical interference, high voltage contamination on supply
 lines, radiation levels etc.
 Environmental influences will affect specific components in specific ways.
 Environmental analysis is thus applicable to components.
+Environmental influences, such as over stress due to voltage
+can be eliminated by down-rating of components as discussed in section~\ref{downrate}.
+With given environmental constraints, we can therefore eliminate some failure modes from the model.
 \paragraph{Operational states.}
 Within the field of safety critical engineering we often encounter 
 sub-system that include test facilities. We also encounter degraded performance

old_thesis/symptom_abstraction/symptom_abstraction.tex

@@ -97,12 +97,12 @@ When all test cases have been analysed, we switch our attention to a higher abst
 % Each `test case' is labelled from the perspective of the failure as seen at sub-system level.
 
 % 
-We can now try to simplfy by determining common symptoms.
+We can now try to simplify by determining common symptoms.
 A common symptom, in this context, is defined as faults caused by different  
 component failure modes that have the same effect from the perspective
 of a `user' of the sub-system.
 
-Test case results can now viewed as failure modes of the sub-sytem or `black box', and grouped together
+Test case results can now viewed as failure modes of the sub-system or `black box', and grouped together
 where there are common symptoms. 
 These are grouped together by joining them with lines. These lines form  collected groups (or `spiders').
 See figure \ref{fig:gensubsys3}.
@@ -320,7 +320,7 @@ In other words we have derived failure modes for this sub-system.
 % is represented as a contour. These contours represent the failure modes of the sub-system.
 % \end{itemize}
 
-This sub-system may now therfore, be represented as three separate failure modes.
+This sub-system may now therefore, be represented as three separate failure modes.
 We may now treat this sub-system as we would a component with a known set of failure modes.
 The failure modes of the Sub-system $SS$ are now the set $SS_{fm} = \{ SP1, SP2, SP_3 \}$.
 
@@ -365,7 +365,9 @@ with known failure modes.
 
 
 
+\section{Boolean definition of a symptom}
 
+Need to explain why its XOR not OR here. 
 
 \section{To conclude}