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<div class="moz-cite-prefix">On 12/07/2020 01:13, Brent Kimberley
wrote:<br>
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<div dir="ltr" data-setdir="false">At the risk of dumbing things
down, I have found that complex multi-disciplinary systems
(e.g. operator-electro-mechanical-software-chemical...) tend
to be unpredictable - even when each of the components were
thoroughly vetted, certified, calibrated - by experts in their
prime. It can be as simple as a decision to use angles
instead of quaterions (singularites), un-realistic design
assumptions, delta retirements analysis instead of global
requirements analysis (requirements conflicts), failure to
optimize globally across multiple dimensions - mass, energy,
momentum, time, jitter, sample frequency, changing physical
systems without updating models & transforms, silent bill
of materials <span>changes</span>, last minute
cables/geometries <span>changes</span>, silent depot changes,
pressure to say yes/pressure to say no, bit error/upset, etc.
It's well and good to say the "O ring" was within spec and
that the problem was else where - in a crisis the question
becomes: is / was the system in spec? This is where devices
like flight data recorder and flight reporting can prove
useful - providing they are used constructively &
responsibly. It the very least, perhaps you could use the
data to determine the failure power law of the fielded system
- or the fleet of systems.<br>
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<p>Makes sense to me ... :-)</p>
<p>Olwen</p>
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