simplify Magnitude and Unit of Measure

[philblackwood]

Updated May 5 with more complete description and comparison with gist 9.6.0
Also includes a spreadsheet with examples.
Change the .txt suffix to .owl to open the owl file.

Updated May 24 to include annotations in owl file, change unitSymbol to symbol, and include 200+ business metrics in spreadsheet. The WORD document includes the example of adding a new unit (watt hours per mile) and minor editorial changes to WORD document.

gist issue 451.docx

abox unit of measure.xlsx

magnitude_pdb.txt

An agile approach to evaluating this would be to get a high level sense of whether it makes sense to consider it, then understand the proposal and tweak it until it does everything it needs to, and then figure out how to get "from here to there". Point-by-point comparison of old vs. new is a larger effort and prone to forgetting things like changing hasUoM to hasUnitOfMeaure. My 2 cents.

[philblackwood]

Probably subsumes the following:

#146 CoherentRatioUnit
#160 numerator, denominator, multiplier, multiplicand
#302 add Magnitude as domain of hasPrecision (I agree with Michael's suggestion to close)
#381 terms for Magnitude and Unit IRIs

I incorporated the proposed solution for #171 and #172: introduce numericalValue

[philblackwood]

For Enterprise customers, it would be more natural to use the term "standard unit" rather than "coherent unit".

[rjyounes]

Dave's thoughts in the attached PowerPoint.
notes on UoM.pptx

[uscholdm]

@philblackwood
I'm struggling to get the essence of the idea so I can evaluate it. I want to be able to look at some definitions and immediately see what it would look like in gist 9.6. I cannot see how to do that yet.

• You say to use Aspect to capture the idea of dimension, but there was no class for dimension in gist.
• It is not clear what is to be used for the broader notion of unit, other than the coherent ones.

The turtle has the following:

:_distance
	a
		owl:NamedIndividual ,
		:Aspect
		;
	skos:definition "The spatial aspect that is measured in meters (coherent unit)."^^xsd:string ;
	skos:scopeNote 'The term "distance" is used instead of the term "length" as in the International System of Units. This allows the term "length" to be used along with "width" and "height" to describe physical objects.'^^xsd:string ;
	.

:_distance_above_sea_level
	a
		owl:NamedIndividual ,
		:Aspect
		;
	skos:definition "An aspect that is measured in meters (coherent unit)."^^xsd:string ;
	skos:scopeNote "The term can be used for the elevation of a geo point or for the altitude of an object."^^xsd:string ;
	.

I cannot easily determine what is similar or different about these two. There is no semantic link to indicate that both have the same coherent unit. The text definitions say how they are similar, but say nothing about how they differ.

• The spatial aspect that is measured in meters (coherent unit).
• An aspect that is measured in meters (coherent unit).

[uscholdm]

There is no class in gist for dimension, on purpose. Each coherent unit corresponds to exactly one dimension, so the latter is unnecessary.

[philblackwood]

all my comments from this thread have been folded into the updated WORD document in the first comment (box)

[philblackwood]

Attached is a hopefully realistic scenario of an Enterprise that needs to introduce a new unit of measure.

It illustrates the kind of guidelines needed for manual calculation of conversion factors and identifies some obstacles to automation of the conversion factors.

This example will be added to the WORD document. The Excel file will be updated with a list of 248 common business metrics and what some of them would look like if the aspect were folded into the unit itself.

Simple example of new units.docx

[rjyounes]

Consider pulling magnitudes and units of measure out of gist core into a separate module as a first step. Not sure if there's a clean breaking point.

[philblackwood]

Interesting idea, Rebecca.

Maybe get some more experience and start to add things back in to the core as they prove themselves (kind of the opposite of removing things that are not being used; add things that are being used).

[uscholdm]

I'd have to have a look, but I think there are a few places where Magnitudes are used to define other things, but even if so, there won't be many.

[philblackwood]

The original entry has been modified to include updates to WORD document (example of watt hours per mile, plus editorial changes).

The .txt file (owl content) has been updated with annotations and to change unitSymbol to symbol.

The excel sheet now includes 200+ examples of business metrics.

[philblackwood]

Here is some data from the QUDT ontology (Quantities, Units, Dimensions, and Types) at http://qudt.org

QUDT units, quantity kinds, quantity kind dimension vectors (with SI terms added), and disciplines.

QUDT has many, many properties, not always used consistently, so I did not include them.

QUDT documentation talks about systems of units other than SI, but their vectors seem to represent SI units (not entirely clear ... that's a topic for a different post).

qudtUnits.txt
qudtQuantityKinds.txt
qudtVectorsWithSITerms.txt
qudtDisciplines.txt

[philblackwood]

To better understand QUDT data for Quantities, Units, Dimensions, and Types, consider the following questions and answers:

  What does the unit MicroGRAY measure?   Absorbed Dose

  What disciplines deal with Absorbed Dose? Radiology and Atomic Physics

You can answer similar questions with the attached data set derived from QUDT (change the .txt suffix to .owl)

qudtValues.txt