robin/Robin_PHD
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

sneaky snoopy

Browse Source
This commit is contained in:
Robin Clark 2012-11-22 11:54:09 +00:00
parent fc89b68499
commit 5732b47ad7
1 changed files with 10 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
submission_thesis/CH5_Examples/software.tex
View File

@ -33,7 +33,8 @@ When we have analysed a software function---using failure conditions
of its inputs as failure modes---we can
determine its symptoms of failure (i.e. how calling functions will see its failure mode behaviour).
We can thus apply the $\derivec$ process to software functions, by viewing them in terms of their failure
We can thus apply the FMMD % $\derivec$
process to software functions, by viewing them in terms of their failure
mode behaviour. To simplify things as well, software already fits into a hierarchy.
For Electronics and Mechanical systems, although we may be guided by the original designers
concepts of modularity and sub-systems in design, applying FMMD means deciding on the members for {\fgs}
@ -410,8 +411,8 @@ With these failure modes, we can analyse our first functional group, see table~\
We now collect the symptoms for the hardware functional group, $\{ HIGH , LOW, V\_ERR \} $.
We now create a {\dc} to represent this called $CMATV$.
We can express this using the `$\derivec$' function thus:
$$ CMATV = \; \derivec (G_1) .$$
%We can express this using the `$\derivec$' function thus:
%$$ CMATV = \; \derivec (G_1) .$$
As its failure modes, are the symptoms of failure from the functional group we can now state:
$$fm ( CMATV ) = \{ HIGH , LOW, V\_ERR \} .$$
@ -502,9 +503,9 @@ for the function.
This postcondition, {\em /* ensure: value is voltage input to within 0.1\% */ },
corresponds to $VV\_ERR$, and is already in the {\fm} set for this {\fg}.
We can now create a {\dc} called $RADC$ thus: $$RADC = \; \derivec(G_2)$$ which has the following
{\fms}:
%We can now create a {\dc} called $RADC$ thus: $$RADC = \; \derivec(G_2)$$ which has the following
%{\fms}:
We can now create a {\dc} called $RADC$ thus:
$$ fm(RADC) = \{ VV\_ERR, HIGH, LOW \} .$$
@ -575,9 +576,9 @@ For single failures these are the two ways in which this function
can fail. An $OUT\_OF\_RANGE$ will be flagged by the error flag variable.
The $VAL\_ERR$ will simply mean that the value read is incorrect.
We can finally make a {\dc} to represent a failure mode model for our function $read\_4\_20\_input$ thus:
We can finally make a {\dc} to represent a failure mode model for our function $read\_4\_20\_input$. %thus:
$$ R420I = \; \derivec(G_3) .$$
% $$ R420I = \; \derivec(G_3) .$$
This new {\dc} has the following {\fms}:
$$fm(R420I) = \{OUT\_OF\_RANGE, VAL\_ERR\} .$$
@ -612,7 +613,7 @@ as a hierarchical diagram, see figure~\ref{fig:eulerswhw}. % see figure~\ref{fig
\end{figure}
% HTR == HATE TO REMOVE
%HTR 18NOV2012 We can represent %the hierarchy in figure~\ref{fig:hd} algebraically,
%HTR 18NOV2012 the analysis hierarchy algebraically using the `$\derivec$' function:
%HTR 18NOV2012 %using the groups as intermediate stages: