# Integration of EMU Overall Design Model Based on Ontology-Knowledge Collaboration
## 4 Integration of EMU Architecture Models
### Construction of Architecture Ontology  
In establishing the architecture ontology of the EMU, based on the MBSE model, the requirement meta-model and the physical architecture meta-model of the EMU are constructed initially. Building upon this foundation, the architecture ontology model of the EMU is established. The ontology design of the EMU adopts the BFO framework, facilitating the conversion between the meta-model and the ontology framework. Duringthe process of building the meta-model, one commonly used modeling method is GOPPRR, as illustrated in Figure 9.  
Meta Object Facility (MOF), as a standardized framework, provides methods for defining and manipulating meta-models, supporting the implementation of MDA. MOF abstracts models into the following four levels: the meta-meta model M3, the meta-model M2, the model M1, and the instance M0, as illustrated in Figure 10.  
The M0 layer represents the most concrete model layer, housing specific domain-specific models. These models delineate detailed information and characteristics of the system or problem. The M1 layer constitutes the model layer, where models ascend in abstraction, no longer entailing details of specific domains but focusing on the essence and fundamental features of the problem. The M2 layer serves as the meta-model layer, elucidating the structure and semantics of M1 layer models. Meta-models define the types and characteristics of various elements (such as classes, attributes, relationships, etc.) used in the models, as well as their relationships. The M3 layer constitutes the meta-meta model layer, where the structure and semantics of the meta-model are delineated. In other words, the M3 layer defines the types and characteristics of the elements (classes, attributes, relationships, etc.) of the meta-model as well as their relationships. The meta-meta model furnishes a framework for defining meta-models that is typically utilized to define the language or form of meta-models. Figure 10: The standard four-layer model system of MOF. Figure 9: The meta-modeling language GOPPRR. Combining the two methods of meta-model construction mentioned above, a specific approach integrating GOPPRR and MDA is illustrated in Figure 11. The basic concepts and relationships of GOPPRR are defined as the M3 layer, while building meta-models for different structures of the EMU set using GOPPRR is designated as the M2 layer. Based on the meta-model of the EMU set, the overall architectural model is constructed at the M1 layer and concrete models are represented at the M0 layer. The specific transformation process is depicted in Figure 10, with the rules being as follows:  
1. The core framework of GOPPR is transformed into the domain ontology class framework of the architectural model. The interrelationships within GOPPR are converted into object attributes, serving as the M3 layer of MDA. 2. The GOPPR meta-model is converted into corresponding subclasses. 3. The GOPPR model is transformed into instances corresponding to the subclasses. 4. Instances are converted into a knowledge graph. 5. The MBSE architectural model, representing the real-world view, is translated into an architectural domain ontology described in the OWL language. The MOF provides a standardized approach for defining and manipulating meta-models, thereby supporting the implementation of MDA [49]. To enhance the comprehensibility and expressiveness of models, the GOPPRR method can be employed to represent entities and relationships within each layer of the MOF models. By integrating GOPPRR with MDA, the advantages of its intuitiveness and flexibility can be fully leveraged, thereby enhancing the reusability of models. By utilizing the BFO framework, the integration of the EMU set architecture is accomplished, and the corresponding relationships are illustrated. In this framework, the basic concepts and relationships of GOPPRR are transformed into class frameworks and properties, the EMU set meta-model is transformed into subclasses, and the overall architectural model is transformed into instances.