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fmmd_concept/fmmd_concept.tex

@@ -582,7 +582,12 @@ there are generally only a handful of SYSTEM level failure modes.
 \subsection{Outline of the FMMD process}
 \label{fmmdproc}
 FMMD builds {\fg}s of components from the bottom-up. 
-Thus the {\fg}s are minimal collections of components
+The lowest level of components are termed base components.
+These are the initial building blocks.
+In Electronics these would be the individual
+passive and active components on the parts~list.
+In mechanics the the levers springs cogs etc.
+Functional groups are collections of components
 that work together to perform a simple function.
 %
 We can perform a failure mode effects analysis on each of the component failure
@@ -603,43 +608,100 @@ modes, the collected symptoms of the {\fg}.
 Because we can now have {\dcs} we can use these to form
 new {\fg}s and we can build a hierarchical `failure~mode' model of the SYSTEM.
 
+The diagram in figure \ref{fig:fmmd_hierachy}, shows one stage
+of the FMMD process. The resultant {\dc} may be used to
+create higher level {\fg}s in later stages.
 %%- Need diagram of hierarchy
 %%-
 %%-
-\vspace{20pt}
-NEED DIAGRAM OF HIERACY
-\vspace{20pt}
+\begin{figure}[h]
+ \centering
+ \includegraphics[width=200pt,bb=0 0 331 249,keepaspectratio=true]{./fmmd_hierarchy.jpg}
+ % fmmd_hierarchy.jpg: 331x249 pixel, 72dpi, 11.68x8.78 cm, bb=0 0 331 249
+ \caption{Example derived component created from the functional group comprised of components a,b,c}
+ \label{fig:fmmd_hierarchy}
+\end{figure}
+
+
+% \begin{figure}[h]
+%  \centering
+%  \includegraphics[bb=0 0 331 249,keepaspectratio=true]{./fmmd_hierarchy.jpg}
+%  % fmmd_hierarchy.jpg: 331x249 pixel, 72dpi, 11.68x8.78 cm, bb=0 0 331 249
+%  \caption{Example derived component created from a functional group comprised of components a,b,c}
+%  \label{fig:fmmd_hiarchy}
+% \end{figure}
+% 
+% \vspace{20pt}
+% NEED DIAGRAM OF HIERACY
+% \vspace{20pt}
 
 
 \subsection{Environmental and Operational States and FMMD}
 
-Introduce the ideas
+Any real world sub-system will exist in a variable environment and may have several modes of operation.
+In order to find all possible failures, the sub-system must be analysed for each operational state
+and environment condition that can affect it.
+Two design decision are required here, which objects should we 
+analyse the environment and operational states with respect to.
+We could apply these conditions for analysis 
+to the functional group, the components, or the derived
+component.
 
-\paragraph {Environmental Conditions and FMMD}
+\paragraph {Environmental Conditions and FMMD.}
 
-HERE talk about environmental effects of a sub-system.
+Environmental conditions are external to the
+{\fg} and are often things that the system has no direct control over.
+Consider ambient temperature, pressure or even electrical interferrence levels.
 
-Define this further by identifying that
-environmental conditions affect components
+Environmental conditions may affect different components in a {\fg}
+in different ways.
 
-for instance a system may be speced for
+For instance a system may be specified for
 0 to 85oC operation, but some components
 may show failure behaviour between 60 and 85
+\footnote{Opto-islolators typically show marked performace decrease after
+60oC whereas another common component, the resistor will be unaffected.}.
+Environmental conditions will have an effect on the {\fg} and the {\dc}
+but they will have specific effects on individual components.
+
+\paragraph{Design Decision.}
+Environmental constraints will be applied to components.
+A component will hold a set of Environmental states that
+affect it. 
+Environmental conditions will apply SYSTEM wide,
+but may only affect specific components.
+%Some may not be required for consideration
+%for the analysis of particular systems.
 
 \paragraph {Operational States and FMMD}
-HERE talk about operational states of a sub-system
 
-Define this further by stating that 
-operational states are effects on a functional group.
-For instance a circuit may have a test line input.
-The fnctional group will there fore have two
-operational states, testing mode and normal mode.
+Sub-systems may have specific operational states.
+These could be a general health level such as 
+normal operation, graceful degradation or lockout.
+Or they could be self~checking sub-systems that are either in a normal or self~check state.
+
+Operational states are conditions that apply to a functional group, not individual components.
+
+
+\paragraph{Design Decision.}
+Operational state  will be applied to {\fg}s.
 
 \paragraph{UML Model of FMMD Analysis}
 
-iDraw a UML model showing the components and the functional group
+Draw a UML model showing the components and the functional group
 with the ENV and OP\_STAT classes associated with them
 
+
+\begin{figure}[h]
+ \centering
+ \includegraphics[width=400pt,bb=0 0 818 249,keepaspectratio=true]{./fmmd_env_op_uml.jpg}
+ % fmmd_env_op_uml.jpg: 818x249 pixel, 72dpi, 28.86x8.78 cm, bb=0 0 818 249
+ \caption{UML model of Environmental and Operational states w.r.t FMMD}
+ \label{fig:env_op_uml}
+\end{figure}
+
+
+
 \subsection{Justification of wishlist}
 
 By applying the methodology in section \ref{fmmdproc}, the wishlist can