MOD, EAD etc calculations for CCR

[Robert Helling]

On 04.11.2014, at 08:45, Willem Ferguson <willemferguson at zoology.up.ac.za> wrote:

Willem,

> The calculation of MOD, EAD and the like that happens in profile.c does not work for CCR because it is based on the gas mix info associated with individual cylinders. Function gas_mod in dive.h is a case in point. I was starting to mess around with these calculations to use dynamic fo2 values for each point on the dive profile (instead of fixed cylinder-specific fo2 values), but then I saw that this function is used in many places, including extensively in the planner.


I am not sure exactly what would be the meaning of MOD for a CCR given the dynamic O2 content. The only way I think this makes sense would be the MOD of the dillutant (since that sets the minimum fO2 that the CCR can deliver and that determines the depth).

Indeed, gas_mod is used in various places but only the call in profile.c is about the current gas, in all other cases the MOD of an explicit cylinder is calculated (essentially to find the max depth to switch to it). What I would probably do is to leave everything as it is and only wrap the call in profile.c with an if(dc.dctype != CCR) { and in the else clause make sure the dillutant is used.

I guess the others EAD, END and EADD should be ok the way they are since they use the info from fill_pressures which takes CCR-ness into account.

What do you think?

Best
Robert

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Robert C. Helling     Elite Master Course Theoretical and Mathematical Physics
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                      Ludwig Maximilians Universitaet Muenchen, Dept. Physik
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