imported>KennethBaclawski: Fix PurpleMediaWiki references

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= [[UoM_Ontology_Standard]] OWL - draft =

Editor: [[RobRaskin|Rob Raskin]], [[ChipMasters|Chip Masters]] and [[HansPeter_de_Koning]]

''... placeholder for the [[UoM_Ontology_Standard]] OWL drafting work''

== [[SysML]] QUDV Ontology ==

Editor: [[HansPeter_De_Koning]]

The input from the [[SysML]] QUDV (Quantities, Units, Dimesions and Values) ontology in OWL2 DL can be found at http://www.omgwiki.org/OMGSysML/doku.php?id=sysml-qudv:qudv_owl .

The ontology is split into two main modules:

* A base ontology '''[[SysML]]-QUDV''' that defines all classes and properties
* The ISQ and SI individuals ontology '''[[SysML]]-QUDV-SI''' for the International System of Quantities and the International System of Units (i.e. finally should cover all of ISO/IEC 80000)

It would be a natural extension to add a third module that defines the most used non-SI units (with conversion factors) from [http://www.physics.nist.gov/Pubs/SP811/appenB.html SP811 "NIST Guide to the SI" Appendix B. Conversion Factors].

The main concepts (classes) in QUDV that correspond closely to VIM and that are probably also applicable to QUOMOS are:

* <nowiki>[[SystemOfQuantities]]</nowiki>
* <nowiki>QuantityKind</nowiki> or <nowiki>[[KindOfQuantity]]</nowiki>, an abstract superclass with subclasses:
** <nowiki>[[SimpleQuantityKind]]</nowiki>
** <nowiki>[[DerivedQuantityKind]]</nowiki>
** <nowiki>[[SpecializedQuantityKind]]</nowiki>
* <nowiki>Quantity</nowiki>
* <nowiki>Dimension</nowiki> or <nowiki>QuantityDimension</nowiki>
* <nowiki>[[SystemOfUnits]]</nowiki>
* <nowiki>Unit</nowiki> or <nowiki>[[UnitOfMeasure]]</nowiki>, an abstract superclass with subclasses:
** <nowiki>SimpleUnit</nowiki>
** <nowiki>DerivedUnit</nowiki>
** <nowiki>[[ConversionBasedUnit]]</nowiki>, an abstract superclass with subclasses:
*** <nowiki>PrefixedUnit</nowiki>
*** <nowiki>[[LinearConversionUnit]]</nowiki>
*** <nowiki>[[GeneralConversionUnit]]</nowiki>
* <nowiki>Prefix</nowiki> or <nowiki>[[UnitOfMeasurePrefix]]</nowiki>
* <nowiki>Scale</nowiki>

=== Remarks on current QUDV implementation ===

# In QUDV, base quantities and base units are modeled as object properties of <nowiki>[[SystemOfQuantities]]</nowiki> and <nowiki>[[SystemOfUnits]]</nowiki> (i.e. roles). We distinguish between ''simple'' and ''base'' kinds of quantity and units:
## A ''simple'' kind of quantity or a ''simple'' unit does not depend (for its definition) on any other kind of quantity or unit.
## A ''base kind of quantity'' is a role that is assigned to selected kinds of quantity in the context of a system of quantities.
## A ''base unit'' is a role that is assigned to selected units in the context of a system of units.
# For the SI system of units, this separation of ''simple'' and ''base'' units e.g. cleanly solves the problem of selecting the <nowiki>PrefixedUnit</nowiki> "kilogram" as a ''base unit''. The "kilogram" is defined through object properties to the <nowiki>Prefix</nowiki> "kilo" and to the <nowiki>SimpleUnit</nowiki> "gram".
# QUDV contains an algorithm written in OCL that precisely specifies how a ''quantity dimension'' for a given kind of quantity in a given system of quantities can be derived automatically.
# In the OWL version of QUDV the <nowiki>[[AffineConversionUnit]]</nowiki> (conversion unit defined with factor and offset to a reference unit) is removed because this is better handled by a <nowiki>[[LinearConversionUnit]]</nowiki> and adding an equivalent property between scale value definitions of different scales. E.g. the offset needed to convert between a ''thermodynamic temperature'' in kelvin and a ''Celsius temperature'' in degree Celsius can be derived when the ''triple point of water'' scale value definitions in both the Kelvin and Celsius scales are declared equivalent.
# The <nowiki>[[SpecializedQuantityKind]]</nowiki> is modeled explicitly because QUDV complies with the strict separation into (MOF) meta levels in UML. QUDV is a pure level M0 UML or [[SysML]] <<modelLibrary>>. Accordingly in OWL2 DL it is not allowed to use metaclasses (using owl:class). This is also not supported in Protégé v4 (yet). In OWL2 Full it would perhaps be possible to model the kind of quantity / quantity specialization relationships more elegantly.

[[Category:WorkSpace]] [[Category:OntologBasedStandards]] [[Category:UoM_Ontology_Standard]]

UoM Ontology Standard OWL Draft - Revision history

imported>KennethBaclawski: Fix PurpleMediaWiki references