density - restructuring quantity values and quantities

[nelekoehler]

Description of the issue

This issue is part of the overarching issue #1510, the restructuring of quantities and quantity values. We already have density quantity values like areal energy density and areal power density (+subclasses) The definitions and axioms need to be adjusted a bit, axioms relating to the quantity need to be added and the quantity density itself should therefore be implemented.

Ideas of solution

Changes of quantity values:

• areal energy density

  • alternative label: areal energy density quantity value
  • definition: An areal energy density value is a quantity value that expresses the magnitude of a certain energy amount per area.
  • axiom: quantity value of some density
  • add axiom: is about some energy

• areal solar energy density

  • alternative label: areal solar energy density quantity value
  • definition: An areal solar energy density value is a quantity value that expresses the magnitude of the arriving solar power per area.
  • add axiom: quantity value of some density
  • add axiom: is about some energy

• areal power density

  • alternative label: areal power density quantity value
  • definition: An areal solar energy density value is a quantity value that expresses the magnitude of the arriving solar power per area.
  • add axiom: quantity value of some density
  • add axiom: is about some power

• areal solar power density

  • alternative label: areal solar power density quantity value
  • definition: An areal solar energy density value is a quantity value that expresses the magnitude of the arriving solar power per area.
  • add axiom: quantity value of some density
  • add axiom: is about some power

• non-scattered radiant flux density

  • alternative label: non-scattered radiant flux density quantity value
  • definition: An areal solar energy density value is a quantity value that expresses the magnitude of the arriving solar power per area.
  • add axiom: quantity value of some density
  • add axiom: is about some power

We could also change the labels and use the current labels as alternative labels.

Adding a quantity:

• density
• Density is a quantity that indicates the amount of something per unit size. (extracted from http://purl.obolibrary.org/obo/NCIT_C45781)

We could also add:

• Area density
• SublassOf density
• Area density is a quantity that indicates the density of a given area.
• --> axioms of density values would then relate to area density.

[nelekoehler]

As discussed in dev-meeting 78, I will look into the UO definitions for area density and mass density again, to see if it is compatible with what I suggested here and if the word size in the definition will be a problem, since size is going to be implemented as a quantity in a different context. Depending on that I will adjust my suggestion here.

[nelekoehler]

I looked through the relevant units of UO:
density unit: "A unit which is a standard measure of the influence exerted by some mass."
mass unit: "A unit which is a standard measure of the amount of matter/energy of a physical object."
area density unit: "A density unit which is a standard measure of the mass exerting an influence on a given area."
mass density unit: "A density unit which is a standard measure of the mass of a substance in a given volume."

we also have the following density units, which are separate from the density units of UO mentioned above:
areal power density unit: "An areal power density unit is a unit which is a measure for the power per surface area."
areal energy density unit: "An areal energy density unit is a unit which is a measure for the energy per surface area."
Is there a reason, why they aren't subclasses of density unit/ area density unit?

In addition, I want to propose new definition ideas for density to incorporate the definitions of UO more and try to avoid size in that context:
Density is a quantity that indicates the influence exerted by some mass/the amount of matter/energy of a physical object.
Area density is a quantity that indicates the mass/the amount of matter/energy exerting an influence on a given area.
"Mass density is a quantity that indicates the mass/the amount of matter/energy of a substance in a given volume."

The quantity values mentioned in my original proposal could then get the axiom quantity value of some``area density

[nelekoehler]

In one of the last dev meetings we decided, that the definitions of UO are confusing and not always consistent.
We don’t want to use density alone and instead want to concentrate on specific terms, some classes could get an alternative term.
I looked again into some other ontologies, a lot of them use mass density as upper class of area density and reusing these terms would maybe confusing as well, since we have the term of mass unit implemented.
Maybe we could use the definition extracted from http://purl.obolibrary.org/obo/NCIT_C45781 which I mentioned above and create the definition for Area density: Area density is a quantity that indicates the amount of something of a given area.