[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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

Jason,

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.

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: XLB-595667
Department: Support UDUNITS
Priority: Normal
Status: Closed
===================
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata 
inquiry tracking system and then made publicly available through the web.  If 
you do not want to have your interactions made available in this way, you must 
let us know in each email you send to us.