Mailing List Archive

Mailing List: techdiver

Message Display

Jack Kellon's article was interesting to read, and mostly factually
correct, but sounded more like an advertisment than a perspective piece on
the merits of certain semi-closed rebreather designs.

I only have one point regarding this stuff that I'd like to make here:

The statement "The more complex the system the more likely a failure will
occur." is a bit misleading. Certainly with increased complexity comes
increased numbers of things that CAN (and probably WILL) malfunction. 
However, component failure and system failure are profoundly different
from the diver's perspective.

Take a rebreather.  Add to it a computer.  The system is more complex with
a computer, so the system is more likely to have a component failure.  If
the failure happens in the computer (arguably the most complex and
failure-prone component in the system), then the diver is screwed.

Now, add two more identical computers, any one of which can fully operate
the system.  The computer complexity has just increased by a factor of 3,
so the probability of a component failure has tripled.  However, since 3
simultaneous computer failures are required to bring the whole system
down, the probability of a system failure is the cube root of the
probability of a single computer failure (i.e., MUCH less -- assuming the
three computers are truly independant entities).

Take home message: Increased complexity does not necessarily equate to
increased probability of a *system* failure (i.e., the important kind).

O.K., that's it (for now....)


Aloha,
Rich

Navigate by Author: [Previous] [Next] [Author Search Index]
Navigate by Subject: [Previous] [Next] [Subject Search Index]

[Send Reply] [Send Message with New Topic]

[Search Selection] [Mailing List Home] [Home]