Added a partition c diagram to describe unitary

state using set theory and an Euler diagram.
This commit is contained in:
Robin Clark 2011-01-09 16:44:26 +00:00
parent 08d9242711
commit 9e6fe66e69
4 changed files with 25 additions and 5 deletions

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@ -720,6 +720,22 @@ of interest when analysing systems from a statistical perspective.
This is of interest for the application of conditional probability calculations This is of interest for the application of conditional probability calculations
such as Bayes theorem~\cite{probstat}. such as Bayes theorem~\cite{probstat}.
Another way to view this is to consider the failure modes of
component, with the $OK$ state, as a universal set $\Omega$, where
all sets within $\Omega$ are partitioned.
Figure \ref{fig:partitioncfm} shows a partitioned set representing
component failure modes $\{ B_1 ... B_8, OK \}$ obeying unitary state conditions.
\begin{figure}[h]
\centering
\includegraphics[width=350pt,keepaspectratio=true]{./component_failure_modes_definition/partitioncfm.jpg}
% partition.jpg: 510x264 pixel, 72dpi, 17.99x9.31 cm, bb=0 0 510 264
\caption{Base Component Failure Modes with OK mode partitioned}
\label{fig:partitioncfm}
\end{figure}
%%- %%-
%%- Need a complete and more complicated UML diagram here %%- Need a complete and more complicated UML diagram here

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@ -665,15 +665,19 @@ the probability that $S_k$ is caused by $B_n$ thus
$$ $$
P(S_k|B_n) = \frac{5.10^{-8} \; 0.1 }{ 10^{-7}} = 0.05 = 5\% P(S_k|B_n) = \frac{5.10^{-8} .\; 0.1 }{ 10^{-7}} = 0.05 = 5\%
$$ $$
To take an example from the diagram (see figure \ref{fig:partitionbcfm2}), where the base component fault cannot Taking an example from the diagram (figure \ref{fig:partitionbcfm2}), where the base component fault cannot
lead to the system failure $S_k$. Taking say $B_9$ which does not overlap with $S_k$ lead to the system failure $S_k$.
Taking say $B_9$ which does not overlap with $S_k$ (i.e. $B_9 \cap S_k = \emptyset $),
we can see that $P(S_k | B_9) = 0$. we can see that $P(S_k | B_9) = 0$.
Bayes theorem applied to $B_9$ becomes $P(S_k|B_9) = \frac{P(B_9) \; 0 }{ 10^{-7}}$ Bayes theorem applied to $B_9$ becomes
As this is a factor in the numerator,
$$P(S_k|B_9) = \frac{P(B_9) .\; 0 }{ 10^{-7}} = 0 = 0\%$$
As $ P(S_k | B_n)$ is a factor in the numerator,
the application of bayes theorem to $B_9$ being a cause for $S_k$ has a probability the application of bayes theorem to $B_9$ being a cause for $S_k$ has a probability
of zero, as we would expect. of zero, as we would expect.