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Fig. 3 A sample of the ontology from our system, showing how a gas turbine is a part, as well
as has a part (compressor), which itself has a part (high pressure turbine blade), that has a sensor
which measures rotation frequency
Fig. 4 The ontology of the system with frequency data added for the frequency concept
With the ontology in place, we then map the sensor data to the domain
model by representing the data as properties of the instances of the corresponding
components. Figure 4 extends the above figure by adding frequency data.
This approach to data management provides an intuitive representation of the
sensor data since it maps the data to the domain model. The queries used to retrieve
the data are also based on the domain model, thus making it easier for different users
to understand and modify the queries. We use SPARQL (SPARQL Protocol and
RDF Query Language), which is a W3C standard for querying the domain model
and data we represent in RDF format (Resource Description Framework). SPARQL
queries were saved and shared between the team to allow easy communication of