# A Categorization of Digital Twin and Model-Based System Engineering Interactions
## 4 Discussion
The concept of the DT adopted in this work is the five-dimensional model presented in [7] and shown in Figure 1. This model was chosen because it allows for the explicit separation of the models and simulations of the virtual entity from the services that the DT must provide, as well as because it clearly represents the databases. For the Perception system, the MBSE tool utilized was the open-source Capella tool, (version 6.1) created by Thales Alenia Space, which integrates the Arcadia method and a domain-specific modeling language closely related to SysML [44]. This MBSE configuration has been adopted in several domains, such as transportation, avionics, and space [45; 46]. Figure 8 presents a high-level view of the logical architecture of the Perception pilot project and its relationships with the external actors: the INPA and the University of Brasilia. In this context, MBSE plays a vital role in defining the system's architecture, ensuring seamless integration between physical entities (PE) such as the K34 tower and space segments and their digital counterparts (VE). The use of Capella and the Arcadia method allows stakeholders--from researchers at the INPA to engineers at UnB--to collaborate through a shared model, reducing ambiguity and promoting informed decision-making. The model presented in this work has been validated by the project stakeholders; however, as the system remains in the design phase, further refinements and modifications may occur in the subsequent development stages. The system is divided into four sections based on the five-dimensional model: the physical entity, digital entity, DT services, and DT database. The physical entity is composed of the micrometeorological tower (MT), the space segment, and the ground segment (located at the LODESTAR). The high-level functions allocated to them are related to sensing the environment and transmitting data. The digital entity includes the DTs of the space segment and the MT. The space segment DT is responsible for monitoring the satellite's health and simulating it, while the MT DT is responsible for monitoring the MT's health and running carbon flux models for its study. The connection dimension present in [PERSON]'s model [7] is explicitly represented in the MBSE model by the connections between the functions. Figure 7: Pilot project data collection infrastructure. Created by the authors. The DT services section demonstrates how the system will interact with internal and external actors. It is responsible for providing information to the actors, including the MT health status, processed MT data, and carbon flux data. Additionally, the system includes tools for the visualization of system-related data. In this high-level view, the DT database has two allocated functions: to store MT data and to store satellite data. The sources of these data can be divided into three categories: in-operation data, experimental data, and synthetic data [47]. The in-operation data are collected during the regular use of the PE. The experimental data are gathered through experiments conducted on the physical entities. To obtain synthetic data, specific mathematical models will be used for meteorological data, and, in the case of the satellite, the hardware-in-the-loop simulation structure of the LODESTAR [48; 49; 50] will be used, with the Ansys Systems Tool Kit (STK) software ([[https://www.ansys.com/products/missions/ansys-stk](https://www.ansys.com/products/missions/ansys-stk)]([https://www.ansys.com/products/missions/ansys-stk](https://www.ansys.com/products/missions/ansys-stk)) (accessed on 3 May 2025)) and a CubeSat Engineering Model (FlaSat) enabling end-to-end technology demonstrations for satellite data collection. The Perception system interacts with two external actors in distinct ways. The INPA receives processed data from the micrometeorological tower via DT services, establishing an alternative communication channel with the tower.