## 1 Introduction and State of the Art
### Model-Based Systems Engineering  
Model-Based Systems Engineering (MBSE) is the formalized application of modeling to support complex system requirements, design, analysis, verification and validation, beginning in the conceptual design phase and continuing throughout the development, and covering all life cycle phases [16]. Models basically represent an effective way to support all the main steps of a System Engineering (SE) process for complex system development, usually represented as a \"V-Model\". There are many different variations of the \"V-Model\" in the literature [17], but the basic philosophy of the SE approach involves the following main, often iterative, steps: the descending branch includes the (i) requirements definition (ii) system decomposition and (iii) model implementation; while the ascending branch comprises the activities of (i) integration (ii) verification and (iii) validation of components, subsystems, and the whole system. The SysML-based methodology presented in [18] helps to carry out the descending branch of the V-Model. It consists of two phases: (i) a Black Box Analysis (BBA) that provides a comprehensive and consistent set of functional and non-functional requirements by analyzing the system from an external point of view, and (ii) a White Box Analysis (WBA) that progressively leads to the internal architecture and behavior of the system. BBA and WBA use SysML diagrams to describe different viewpoints of the system. SysML [19] is a unified general-purpose modeling language for high-level descriptive models; it also supports traceability among the different viewpoint diagrams.  
In addition to designing the system to respond to the functional requirements, it is important to make sure that failures and dysfunctions among the system does not cause a big harm. To this end, Safety analysis and particularly Model-Based Safety Analysis (MBSA) must make part of the whole design process. MBSA requires the use formal languages such as AltaRica [20,21] in order to model and simulate the system behavior in different conditions in order to assess that the system satisfies the safety requirements.  
Generally, model-based approaches deal with the same system providing different models according to the design viewpoint. Different models means different data often developed by using different languages and software. The development of a unified system model or linked models to obtain consistent system models is still a challenge.  
Some researchers have dealt with the consistency of models through different approaches. For instance, the authors in [22] proposed an approach named SafeSysE which proposes both a methodological approach that specifies the sequence of exchange between system and dependability analyses and also allows the generation of (partially filled) safety-related artifacts from system models to ensure their consistency. [PERSON] et al. [23] dealt with MBSE and MBSA integration through model transformation from SysML semi-formal models into AltaRica 3.0 formal language elements taking into account the system behaviour by using state machine elements. [PERSON] et al. in [24] dealt with model synchronization through the abstraction of the different models into a common formalism and then their comparison and synchronization if inconsistencies are detected. Although some researchers have worked on the connection of different virtual models, no one provides a useful generalized method to link models.