Add term hub height

[sfluegel05]

Description of the issue

Part of oeo developer meeting 8

Part of issue OpenEnergyPlatform/oeo-extended#5

Ideas of solution

wind energy converting unit has quality hub height
class hub height (hub height is a quality)
has quantity value length value

length value is about hub height

object property has quantity value

Existing definitions:

• https://www.daviddarling.info/encyclopedia/H/AE_hub_height.html
• https://www.wind-lexikon.de/cms/lexikon/98-lexikon-n/255-nabenhoehe.html

Workflow checklist

• I discussed the issue with someone else than me before working on a solution
• I already read the latest version of the workflow for this repository
• The goal of this ontology is clear to me

I am aware that

• every entry in the ontology should have a definition
• classes should arise from concepts rather than from words

[sfluegel05]

definition for hub height: Hub height is a quality of a wind energy converting unit that measures the distance between surface and center-line of the wind rotor.

[sfluegel05]

definition for length value: Length value is a quantity value that has a length unit as unit.

[sfluegel05]

definition for has quantity value: A relation between an entity and a quantity value.

[stap-m]

@jannahastings can we import is about from somewhere? And do you you have any better ideas for the definition of the has quantity value property?

[stap-m]

Now, we've implemented length value has part length unit. This seems weird, but we don't have a better soluition for now. See also #508

[l-emele]

#509 was merged, so can we close this issue?

[stap-m]

Not yet. We should solve the unit issue #508 first.

[jannahastings]

@jannahastings can we import is about from somewhere?

Yes. is about is in IAO, so we can import it from there. I will add it to our IAO extract.

[stap-m]

After including is about and restructuring unit #519, I am closing this.