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now have 1,2,3 8
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Robin P. Clark 2013-09-11 16:33:22 +01:00
parent a476926969
commit d7dee62f42
1 changed files with 8 additions and 6 deletions
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submission_thesis/CH8_Conclusion/copy.tex
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@ -258,8 +258,8 @@ resistor{\lambda}_p = {\lambda}_{b}{\pi}_Q{\pi}_E
Thus thermistor, bead type, `non~military~spec' is given a FIT of 315.0.
%
\frategloss
Using the RIAC finding the following table (table \ref{tab:stat_single}) can be created,
showing the FIT values for all single failure modes.
Using the RIAC finding the following (table~\ref{tab:stat_single}) can be created which
presents the FIT values for all single failure modes.
%\glossary{name={FIT}, description={Failure in Time (FIT). The number of times a particular failure is expected to occur in a $10^{9}$ hour time period.}}
\fmmdglossFIT
%
@ -331,7 +331,7 @@ failure rate statistics to double failures can also be determined.
%%
%
Considering the failure modes to be statistically independent
the FIT values for all the combinations
the FIT values for all the combinations of
failures in the electronic examples from chapter~\ref{sec:chap5} in table~\ref{tab:ptfmea2} can be calculated.
%
The failure mode of most concern, the undetectable {\textbf{FLOATING}} condition,
@ -339,8 +339,9 @@ requires that resistors $R_1$ and $R_2$ both fail.
%
Multiplying the MTTF probabilities for these types of resistor failing gives the MTTF for both failing.
%
The FIT value of 12.42 corresponds to
$12.42 \times {10}^{-9}$ failures per hour. Squaring this gives $ 154.3 \times {10}^{-18} $.
The FIT value of 12.42 corresponds to $12.42 \times {10}^{-9}$ failures per hour.
%
Squaring this gives $ 154.3 \times {10}^{-18} $.
%
This is an astronomically small MTTF, and so small that it would
probably fall below a threshold to sensibly consider.
@ -359,7 +360,8 @@ In a large FMMD model, system/top level failures can be traced
down to {\bc} {\fms}.
%
To determine the MTTF probability
for a system level failure, the MTTF statistics are added for all its possible causes.
for a system level failure,
the MTTF statistics are added for all its possible causes.
%
Thus even for large FMMD models accurate
statistics for electronic sourced failures can be calculated.