OntoCAPE is a large-scale ontology for chemical process engineering. OntoCAPE is partitioned into 62 sub-ontologies, which can be used individually or as an integrated suite. The sub-ontologies are organized across different abstraction layers, which separate general knowledge from knowledge about particular domains and applications. The upper layers have the character of an upper ontology, covering general topics such as mereotopology, systems theory, quantities and units. The lower layers conceptualize the domain of chemical process engineering, covering domain-specific topics such as materials, chemical reactions, or unit operations.

Morbach, Jan, Aidong Yang, and Wolfgang Marquardt. "OntoCAPE—A large-scale ontology for chemical process engineering." Engineering Applications of Artificial Intelligence 20, no. 2 (2007): 147-161. [http://www.avt.rwth-aachen.de/AVT/index.php?id=730&L=1]