How to extend the QUDT ontology?

Hello, I am the primary author of QUDT. Currently we are doing a major revision with extensive documentation. This revision is 1.2 and there are many refactored graphs to support partitioning, extensibility and transformations, not least documentation support. Some key features of 1.2 are:

1. Units and Quantities are organized by domain with separate graphs for "Systems of Units" and "Systems of Quantities".
2. Alignment with ISO 80000
3. Usage, Naming and Design Rules for Units and Quantities, including references to NIST
4. First release of the datatypes ontologies and vocabularies
5. Support for LaTeX rendition and documentation
6. Use if the PROVO ontologies for derivation and provenance
7. Vocabularies for aerospace (NASA related) and Life Sciences based on a classification of science and engineering domains
8. SPIN rules for generating new units based on prefixes and dimensional analysis (examples: 'unit:KG-PER-HR' and 'unit:J-PER-KG-K-PER-M3'
9. SPIN rules for units conversion based on dimensional analysis
10. Ability to use QUDT for dimensional datatype properties

Release 1.2 is a considerable effort to provide an extensive treatment of units and quantities. We are hoping to have a beta release by the end of the year. Currently the priority is the generation of a QUDT-based PDF Handbook using Semantic Markdown and LaTeX generators that convert the OWL content based on SPIN Web Pages (SWP) Technologies.

I will post more news and links before the end of the year.

Anyone interested in beta testing 1.2 can contact me.

Regards, Ralph Hodgson (@ralphtq)

Not in direct relation to your question, but nevertheless a slight caveat; I just spent a few months with a similar problem (specifically creating types for water quality). We ended up using muo, unit and ucumunit because of muo's rather sane way of handling creation of types.

This is quite a specialist question (might be best posed directly to the authors of the ontology) but having had a quick skim through their examples:

Some units we need are not in QUDT, what is the best way to integrate them? For example year, month, day ... Is this correct?

It looks like it follows the example for, e.g., MilliSeconds here, so yes.

Also, how to add synonyms, e.g. add 'sec' to #SecondTime? This is how we did it, but it seems tedious:

You could consider using owl:sameAs instead.

And last question: what is the best way to add a unit like 'l/min' (liter per minute). QUDT has #CubicMeterPerSecond (of type #VolumePerTimeUnit), so I could add one more entry like Week above, but then I need other entries for: l/h, ml/s, dl/week, etc. Is there any generic way to say every combination of #VolumeUnit per #TimeUnit is a #VolumePerTimeUnit

I would suggest that if they have not already defined the class #VolumePerTimeUnit and its instances in such a manner, then this would not be possible. In their units ontology, they write all such units out explicitly with qudt:conversionMultiplier and qudt:conversionOffset from the base unit (e.g., see #CubicMeterPerHour).

Can I dare ask why Millimeter isn't in the QUDT and Centimeter is? Is everyone expected to convert every mechanical dimension they see into a unit that is in the QUDT? Seems like a major assumption or possibly oversight there.

Hello xsber,

Millimeter, along with all other scaled units, is in QUDT 1.2. Here are 2 screenshots from the QUDT Handbook (almost 4000 pages now - generated from the ontologies): index page - http://qudt.org/1.2/screenshots/hb-index-millimeter.png and from the entry page - http://qudt.org/1.2/screenshots/hb-page-millimeter.png

Currently we are generating all dimensions and identifiers for quantities and units. And doing QA on the ISO-80000 RDF/OWL representations. Disambiguating some quantities across domains.

Thanks for your feedback.