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[UDUNITS #XLB-595667]: Isotope conversions in the UDUNITS package


Are the deltas in the first two equations squared?

> I've never developed a use case before, but I'll give it a shot based on some 
> information I see at 
> https://www.usability.gov/how-to-and-tools/methods/use-cases.html. I'm going 
> to focus on Hydrogen, but the same use cases should more-or-less apply to 
> other isotopes, as well. If I totally missed the mark, just let me know and 
> I'll try again.
> Use case 1: Conversion to permille from proportional (dimensionless or 
> decimal) delta values of 2-Hydrogen.
> Actor: User with isotope data in proportional format.
> Basic flow: The following relationship is used:
> [H2_decimal_to_permille.gif]
> Use case 2: Conversion from proportional to permille delta values of 
> 2-Hydrogen.
> Actor: User with isotope data in proportional format.
> Basic flow:
> [H2_permille_to_decimal.gif]
> Use case 3: Conversion of ratio data to proportional data, given a known 
> standard, for 2-Hydrogen.
> Actor: Users with ratio isotope data interested in it's equivalent VSMOW 
> (Vienna Standard Mean Ocean Water) form of proportional delta value.
> Basic flow:
> [H2_ratio_to_decimal.gif]
> Note: There is also a VSMOW standard (the original), as well as a GISP 
> (Greenland Ice Sheet Precipitation),  SLAP (Standard Light Antarctic 
> Precipitation), and SLAP2 standard.
> Note: For Oxygen, the same standards above also apply with the addition of 
> the VPDB (Vienna Pee Dee Belemnite) standard.
> Use case 4:
> Actor: Users with isotope ratio data interested in the fractional abundance 
> of those ratios.
> Basic flow: If there are only to isotopes of interest.
> [H2_ratio_to_fractional.gif]
> Alternative flow: If there are three isotopes of interest then those need to 
> be accounted for. This is generally a rare, case, but not unheard of.
> Alternative flow: More than three isotopes of interest. Very rare.
> I think I'll leave it there for now to see what you think, but hopefully that 
> made a bit of sense. If it didn't, I totally understand. One of the reasons 
> I'm trying to figure how to develop an easier means of converting between 
> isotope units is to ease the burden of using isotopes, especially for 
> students and managers, who may not find these conversions intuitive.

Steve Emmerson

Ticket Details
Ticket ID: XLB-595667
Department: Support UDUNITS
Priority: Normal
Status: Closed
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