# Integration of EMU Overall Design Model Based on Ontology-Knowledge Collaboration
## 3 Integration of EMU Requirement Models
### Requirements Ontology Construction
published by the International Electrotechnical Commission (IEC) and enjoys international recognition, with the terminology table being elaborated on in Table 1.  
Utilizing ReqIF to export its requirement data streamlines the sharing and collaboration of requirement information. Hence, in the process of constructing the requirement model for an EMU, ReqIF is employed to standardize requirement specifications, ensuring the accurate transmission of requirements. During the EMU requirement construction process, meticulous requirement collection, identification, and analysis take precedence to ensure a comprehensive grasp of various system aspects. This entails close collaboration with multiple stakeholders, such as vehicle manufacturers, operators, and maintenance personnel, to ensure thorough consideration of all stakeholders' expectations and requirements. Through requirement collection and analysis, a comprehensive roster of requirements gradually emerges, encompassing system functionality, performance characteristics, safety standards, and other facets. Integrating these collected, identified, and analyzed requirements with an ReqIF to construct the requirement ontology for an EMU facilitates the unified management and exchange of requirements, ensuring consistency and traceability. This step contributes to establishing an ontology characterized by hierarchy, coherence, and precise definitions, furnishing a dependable foundation for EMU design and development. Figures 4 and 5 visually depict the stakeholders and some requirements of the EMU requirement model. These graphical representations aid in intuitively comprehending the structure and relationships of EMU requirements. Figure 4 delineates the relationships among various stakeholders, including manufacturers, maintenance teams, crew members, etc., vividly showcasing the diversity and complexity of requirements. Meanwhile, Figure 5 offers a stakeholder-centric analysis of requirements, furnishing specific content for the EMU system's requirements. The construction of this requirement model and its graphical representation facilitate communication among team members, rendering the comprehension of system requirements more intuitive and comprehensive. Simultaneously, it serves as an effective tool for future requirement changes and tracking, ensuring the entire EMU project proceeds in accordance with well-defined requirements. During the construction of the ontology, users can clearly visualize the structure of the EMU requirement ontology and understand the hierarchical relationships between various classes and the definition of attributes using the Protege tool [40]. This visual representation assists users in gaining a better understanding of the organizational structure of the requirements ontology, quickly identifying the connections between concepts, and thereby engaging in more targeted ontology editing and expansion. The construction of the EMU requirement ontology, facilitated by Protege, as depicted in Figures 6 and 7, provides users with an intuitive and efficient operational platform. This not only enhances the efficiency of ontology construction but also furnishes users with better tools and support to ensure the quality and consistency of the requirement ontology.