On 05.11.2014, at 17:37, Willem Ferguson <[email protected]> wrote:
Willem,
> 1) This patch has an unintended consequence: The ending cylinder pressure for
> the diluent cylinder (as seen on the equipment tab) is changed to reflect
> that of the ending pressure of the oxygen cylinder. The diluent cylinder
> index for the Poseidon diluent is the dreaded and infamous 1. We hardcode the
> cylinder IDs here while reading in the dive log because it is very specific
> to the Poseidon. In addition, even though these specific two cylinders have
> already been assigned to enum values of oxygen and diluent respectively, we
> are in the process of setting up the cylinders, so we cannot already use the
> functions that use these enum values.
> So: dive->cylinder[1].sample_end.mbar for this sample dive has a value of
> 141, that of the oxygen cylinder. The correct ending value for this variable
> is 137. I have carefully looked around the code around line 600 in file.c but
> cannot see the cause of this problem. Run the code with and without your
> patch and see the difference.
>
> 2) A question just to improve my understanding of the code. If the
> explicit_first_cylinder() result is diluent, does this mean that the deco
> requirements are calculated for the gas in the diluent cylinder? In this case
> the diluent is air, but the displayed ceilings do not (at first sight) appear
> to be shallower than that for air dives to the quivalent depths. For
> instance, if I simulate the sample dive as an air dive using the planner, the
> dive extended to 70 min for sufficient deco. So if the ceilings reflect the
> pn2 values at the various depths as actually calculated at each point on the
> profile, why does it matter whether one starts with cylinder 0 or cylinder 1?
after getting a good night of sleep, I am reading this again (several times
indeed) and I am not sure I understand what you are trying to tell me.
I understand that for a CCR segment there are two cylinders in use
simultaneously, diluent and O2. For the deco calculation to work, it has to
know that the diluent is (and figure the actual breathing gas from that and
ambient pressure and set point).
The other question is what to plot as a pressure (as in cylinder pressure, not
partial pressure) graph. Ideally both, but at the moment we don’t do that. So,
at least for the .txt import it seems we are plotting diluent pressure. Is that
what you are complaining about?
MY question is: Where does this information (and also the information about the
O2 cylinder pressure) as a function of time come from? Is that in the .txt/.csv
as as far as I can see, it is not in the .xml. Or do we only have start and and
pressures for the cylinders (again they seem to be missing for the xml and I
don’t know about the others). In that case, for OC, cylinder pressures to be
plotted get interpolated assuming a constant SAC. But for CCR that (as was
discussed at length before) does not make sense. For O2 one might try a depth
independent consumption (leading to a linear plot of O2 cylinder pressure) but
for diluent it is ascent/descent dependent in a complicated way that we have
not yet figured out how to model, so at the moment, any interpolation would be
bogus.
So, what to you expect to see and what are you seeing instead?
Best
Robert
--
.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oO
Robert C. Helling Elite Master Course Theoretical and Mathematical Physics
Scientific Coordinator
Ludwig Maximilians Universitaet Muenchen, Dept. Physik
Phone: +49 89 2180-4523 Theresienstr. 39, rm. B339
http://www.atdotde.de
Enhance your privacy, use cryptography! My PGP keys have fingerprints
A9D1 A01D 13A5 31FA 6515 BB44 0820 367C 36BC 0C1D and
DCED 37B6 251C 7861 270D 5613 95C7 9D32 9A8D 9B8F
signature.asc
Description: Message signed with OpenPGP using GPGMail
_______________________________________________ subsurface mailing list [email protected] http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
