# Systematic Literature Review of MBSE Tool-Chains
## 4 Discussion
### Detailed Analysis from Findings
#### 4.2.3 Techniques Analysis of MBSE Tool-Chains  
To fully identify the techniques for MBSE tool-chain development, a series of the most frequently mentioned life-cycle properties are summarized in Figure 6. Among the 16 investigated properties, _safety_ and _reliability_ were the most frequently mentioned. These two properties were specifically supported by an OMG group, which consisted of both industry and academia and defined a new standardized UML profile to support safety and reliability analysis [22]:  
* Safety refers to the application of safety engineering in MBSE tool-chains, identifying potential dangers in the system through risk model definition and simulation analysis for taking effective control measures to minimize the dangers. For example, [PERSON] and [PERSON] extended the scope of UML AP to also cover the development and design of safety systems. The work was targeted to the requirement concepts of the profile but also to documenting the results of risk and hazard analysis, which aided in the discovery of the information when the developers needed it [23]. [PERSON] et al. presented a functional safety analysis approach in the process of system modeling, and the analysis of the resulting model was performed through a stochastic Bayesian model. This approach strove to both bypass the necessity for costly hardware testing and integrate the functional safety analysis into an intuitive component development process [24]. * Reliability is defined as the ability of a functional unit to perform a required function under given conditions for a given time interval [25]. For example, [PERSON] et al. explored the integration of failure mode and effects analysis (FMEA) and MBSE by generating FMEA models from MBSE models to support system reliability design [26]. Furthermore, [PERSON] et al. generated FMEA models from structural and behavioral diagrams in SysML models and used the AltaRica language to compute the reliability indicators [27]. Moreover, the reliability of the code generator has been identified as a key concern in automatic code generation. In order to investigate the model-based design approach for control system software development, [PERSON] et al. constructed the traceability between Simulink models and the generated program code by developing reliable code generators [28]. The result implies that _safety_ and _reliability_ are two important life-cycle properties in aerospace and vehicles, because most of the papers we collected were from these two domains, as shown in Figure 4.  
As shown in Figures 7-16, we analyzed the technical aspects of the MBSE tool-chains to support system development, including modeling purposes, modeling languages, modeling methods, etc. Figure 7 demonstrates that _understanding problems at an abstract level_ is the most common purpose of tool-chains. As shown in Figure 8, the formalisms of requirement, function, behavior, logic, physical architecture, interface definition, and verification & validation are used to understand the system problems at the abstract level. As the most frequently researched aspect, the requirement not only needs to tell system engineers what the system needs to do, but also needs to improve the traceability of design problems through verification [29; 30]. Figure 9 shows that SysML [31] is widely used in terms of modeling languages. As for modeling methods, due to the ability of abstract system architectures, meta-modeling is widely used in MBSE, as shown in Figure 10. Simulation is an important part of system design; therefore, simulation methods are widely used in MBSE tool-chains. Only about half of all the papers included simulation in their tool-chain, as shown in Figure 11. From the perspective of modeling tools in Figure 12, MATLAB and Simulink were the most widely used tools in tool-chains. As a visual simulation tool, Simulink provides a graphical editor, a customizable module library, and a solver which can perform dynamic system modeling and simulation.