Need to support measures of temperature, force, work, etc. I'm currently working on this as well as on the issue of having directional vectors. Anticipate a new release with both features in about 2 weeks.
Present knowledge of measurements encopasses much more than the present attempt.
Please see the fundamental measurements in SI (seven by now) and please note you to include in your system a way to have the derived units which are compound through the fundamental ones but due the way they are defined an adimensional changes the nature of the unit.
In fact a supplemetary unit is for all purposes "adimensional" but nevertheless necessary for ordinary work in Science.
There are currently only a handful of Measurement instances (apx. 60) and the reasoner takes 1-2 seconds to run. The performance now is perfectly acceptable but I think that with a non-trivial number of instances (e.g., thousands or more) performance may get prohibitively slow. One potential way to address this is to translate the SWRL rules into SPARQL transformations and run them in a triplestore such as AllegroGraph. In previous ontologies I've done this when performance became an issue and SPARQL in a triplestore is at least an order of magnitude faster than SWRL. Another option is to try more efficient SWRL implementations, I think Drools is more efficient than SWRL with the Pellet reasoner as I'm currently using it.
I want to model some concepts from physics and Thermodynamics and realize I need to add support for vectors as well as scalars. I.e., velocity as well as speed. The design of the current ontology should make this easy and I plan to add the capability to specify direction in 2 and eventually 3 dimensions using Radians or Polar Coordinates. I'm interested if anyone has a preference in either form of representation (i.e., Radians or Polar).