# EMMO use case for vertical interoperability

Vertical interoperability is about interoperability across two or more granulaty levels.

In this use case we study the welded interface between an aluminium and a steel plate at three granularity levels.
In this case, the granularity levels corresponds to three different length scales, that we here denote _component_, _microstructure_ and _atomistic_ scale.

## Creating an EMMO-based user case ontology

The script [define_ontology.py](define_ontology.py) uses the Python API for EMMO to generate an application ontology extending EMMO with additional concepts needed to describe the data that is exchanged between scales.
The user case ontology can then be visualised with the script [plot_ontology.py](plot_ontology.py).

### Defining the needed material entities

![Material entities (shown in context of the `state` branch in EMMO.](figs/materials.svg)

### Assigning properties to material entities

Note that we here also assign properties to `e-bonded_atom`, even though `e-bonded_atom` is defined in EMMO.

![Relating material entities to properties.](figs/properties+materials.svg)

### Assigning units to properties

We choose here to consistently use SI units for all scales (even though at the atomistic scale units like Ångström and electron volt are more commonly used).

![Relating properties to units.](figs/units+properties.svg)

### Assigning types to properties

In order to be able to generate metadata and to describe the actual data transferred between scales, we also need to define types.

![Relating properties to types.](figs/types+properties.svg)

### The new application-ontology

![All classes in the user case ontology.](figs/usercase_ontology.svg)

The final plot shows the user case ontology in context of EMMO.

![The user case ontology shown in context of EMMO.](figs/usercase_ontology-parents.svg)