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HajoRijgersberg
Add units based on angstrom
There is Angstrom in the ontology, but units derived from it are missing. For example, A^2 for area, A^3 for volume, A^{-1} for wavenumber. Are they planned to be added in future releases?
Thanx, that's a good point. Yes, I'll include them. I'll start with the examples you mention. Do you have any other relevant examples of compound units where the angstrom is used?
Thank you, that would be great! I will also need density in a.m.u. per A^3, but I am not sure if this is a commonly used unit.
No prob if a unit is not commonly used. We will only not refer to it as a commonly used unit (we have this property in OM). I see we have some backlog with renaming the unified atomic mass unit to dalton. But for now I'll still use the former in the definition of your suggested density unit. At a later stage I think we will rename to dalton, but I have to study it in more details first.
I have just added them: square angstrom, cubic angstrom, reciprocal angstrom and unified atomic mass unit per cubic angstrom. For the latter, I have specified the symbol u/Å, if that's Ok with you. I can also add an alternative symbol, which may be required for unified atomic mass unit. If you could check the additions I made, that would be great! :)
Hello Hajo,
I came across misprints (need correction), and few observations (optional) related to angstrom. For the line numbers I use the om-2.0.rdf file version 2.0.47
Line: 2150. Misprint: The language of label does not match the xml:lang value. <om:Unit rdf:about="&om;angstrom"> <rdfs:label xml:lang="en">ångström</rdfs:label> <== HERE <rdfs:label xml:lang="nl">ångström</rdfs:label> <om:alternativeLabel xml:lang="en">angstrom</om:alternativeLabel> <om:alternativeLabel xml:lang="nl">angstrom</om:alternativeLabel> <== HERE <rdfs:comment xml:lang="en">The ångström is a unit of length defined as 1.0e-10 metre. <== HERE The unit is often used for wavelengths of electromagnetic radiation or to express the sizes of atoms and molecules.</rdfs:comment>
Line: 3047. Observation: squareAngstrom does not have an xml:lang="nl" label. This is optional, only for consistency with the rest of the ontology. Not critical for me if you prefer to leave it as it is. <om:UnitExponentiation rdf:about="&om;squareAngstrom"> <rdfs:label xml:lang="en">square angstrom</rdfs:label> om:symbolÅ2</om:symbol>
Line 3965. Same as previous: <om:UnitExponentiation rdf:about="&om;cubicAngstrom"> <rdfs:label xml:lang="en">cubic angstrom</rdfs:label> om:symbolÅ3</om:symbol>
Line 9386. Same as previous: <om:UnitExponentiation rdf:about="&om;reciprocalAngstrom"> <rdfs:label xml:lang="en">reciprocal angstrom</rdfs:label> om:symbolÅ-1</om:symbol>
Thank you, Paul.
Thanx so much Paul, for checking! I have immediately corrected the above, where noted that I assume that you meant that the English alternativeLabel should be changed rather than the Dutch alternativeLabel (to ångström). (Note that in English the unit is called angstrom where in Dutch it is ångström.) I have not yet added the Dutch labels for the compound angstrom units since I still have to add Dutch labels to many, many compound units. On my (longer-term) to-do list! :) Could you please check again? Thanx so much in advance!
I think this is still wrong. On line 2153: <om:alternativeLabel xml:lang="en">ångström</om:alternativeLabel> <om:alternativeLabel xml:lang="nl">angstrom</om:alternativeLabel>
Thanx. I think you have a point. I'll change them to unofficalLabels, i.e., labels that may be used by people in practice, in a minute. (At least, that is what that property is meant for.)
We got misunderstanding. Let me clarify it. I mean in xml:lang="en" it should be angstrom, not ångström. And similarly in xml:;ang="nl" it should be ångström not angstrom. The alternativeLabel is goog enough for me.
Oh... I got it.. It IS supposed to be reverse. Great idea! Ignore my previous message
P.S.: I do think that the unofficialLabel is better here than the alternativeLabel.
Sorry, I do not have experience with the alternative/unofficial, don't feel the difference, cannot comment. In this question you'd better do they way you prefer. And I am glad we came to this improvement. Thanks again!
No prob, I really appreciate your comments! :) I think the alternativeLabels should be really correct (still), where the unofficialLabels may (even) be incorrect, but reflect usage in practice. I'm also very glad. Thanks to you! :)
Hi, Hajo,
This request is related to the previous discussion, so I did not create a new issue.
Please add two more units: reciprocalCubicAngstrom and reciprocalCubicNanometre as units of measure for the number density.
I wonder, is it possible for reciprocalCubicNanometre to add an alternative name with meaning “1/(1000 A)”. I am not sure what is a good name for it. May be Reciprocal1000CubicAngstrom, or reciprocalThousandCubicAngstrom, or reciprocalOneThousandCubicAngstrom. You may treat this alternative name request as a low priority.
Comment: Since OM-2 already has reciprocalCubicMetre and reciprocalCubicCentimetre, and hopefully will have reciprocalCubicNanometre, you may also consider to add: reciprocalCubicMillimetre and reciprocalCubicMicrometre (or reciprocalCubicMicron?) for continuity. I don’t really need them now, and not sure whether these units are widely used, so I don’t mind if you decide to ignore these two.
Thanks!
Hi Paul,
Apologies for my late reply. The times have been very busy, like with anyone I guess, but still... I'll add the two units within a few weeks, would that be Ok with you?
As to 1/1000 A, I'm not sure, let me think about it. Usually any unit, like angstrom, is defined in terms of SI units, in this case metre. Giving reciprocalCubicNanometre as alternative label '1/1000 A' seems like the other way round... Please let me think about it, and any feedback is appreciated of course. My first feeling says it would be logical to declare Reciprocal1000CubicAngstrom and define it terms of (cubic) metres. Would what you think?
Certainly, thanx, I'll also define reciprocalCubicMillimetre and reciprocalCubicMicrometre along with the above-mentioned. Have to dive into the micron version (reciprocalCubicMicron), since I don't know by heart if we have defined the micron as an individual unit or as an alternative label to micrometre. If the latter, I could add it as an alternative label.
Cheers, Hajo
Hi Hajo, Nice to hear from you. Thank you for the reply, few weeks is fine.
Regarding '1/1000A^3'. You raised a good question: whether to have two separate units for '1/nm^3' and '1/1000A^3', or only one. 1/nm^3 should be added as a part of SI unit hierarchy any way. And my original idea with alternative name was to reduce the number of instances. But I agree, keeping the ontology structure standard is more important than a separate unit. So I agree with your conclusion: it's better to create a new unit 1/1000A equal to 10^-27 metre. And in this case I think I do NOT need even to mention that it is equal to 1/nm^3.
Thanks again, Paul.
Hi Hajo, Nice to hear from you. Thank you for the reply, few weeks is fine.
Regarding '1/1000A^3'. You raised a good question: whether to have two separate units for '1/nm^3' and '1/1000A^3', or only one. 1/nm^3 should be added as a part of SI unit hierarchy any way. And my original idea with alternative name was to reduce the number of instances. But I agree, keeping the ontology structure standard is more important than a separate unit. So I agree with your conclusion: it's better to create a new unit 1/1000A equal to 10^-27 metre. And in this case I think I do NOT need even to mention that it is equal to 1/nm^3.
Thanks again, Paul.
Hi Paul, Thanx, yes that seems clear. I'll make work of it during this week. Cheers, Hajo
Hi Hajo,
Please check also this issue. I think it is still pending.
Thanks, Paul.
Hi Paul,
Sorry it took longer. But I have just defined reciprocalCubicAngstrom, reciprocalCubicMillimetre, reciprocalCubicMicrometre and reciprocalCubicNanometre as number density units. If you could please have a check if I have made no mistakes, that would be appreciated. Thanx in advance! :)
Cheers, Hajo