## 3 ERSA (Engineering Design Research Meta-Model Based Systematic Analysis) Process
### Phase 3-Completion of the Collection  
The third phase of the process consists of completing the collection by incorporating related articles for each _citation pool_\(C(b_{i})\). For every _citation pool_\(C(b_{i})\), a set of new articles is identified through a search for thematic similarity, denoted as \(\Gamma_{C(b_{i})}=\left\{\gamma_{1},\ldots,\gamma_{i},\ldots,\gamma_{m}\right\}\) and named _thematic group_ related to the _citation pool_\(C(b_{i})\). As stated in [PERSON]'s [27] work on snowballing, it is always relevant to use different strategies to cover the literature as comprehensively as possible. The set of articles is therefore extended to include more recent works and to include works that may have been overlooked in the previous phase of the process. The Research Rabbit process [29], which uses a list of works to visualize their interconnections through their common citations, permits to find studies on similar topics. In this case, the list of articles collected in snowballing phase is used in Research Rabbit process. The criteria applied for the research in Research Rabbit process are the same as those applied in the snowballing phase. The list is completed by articles suggested by Research Rabbit, contributing to its continuous growth. This phase stops when Research Rabbit has no other studies to suggest than the one already present in the list or those not considered in the focus of the study. The complete collection of articles \(\Sigma\) is defined as the union of three sets: the baseline articles set (\(B\)), encompassing all initial articles aged up to \(\theta\) years old; the set of all citation pools (\(C(b_{i})\)), representing the citing articles for each baseline article \((b_{i})\); and the set of thematic similarity articles (\(\Gamma_{C(b_{i})}\)), comprising new articles identified through thematic similarity searches for each citation pool:  
\[\Sigma=B+\bigcup_{i=1}^{n}C(b_{i})+\bigcup_{i=1}^{n}\Gamma_{C(b_{i})} \tag{4}\]Phase 4-Representation of Methodologies Using Engineering Design Multilayer Attributed Network for Computation  
Each paper's methodology is represented by the _engineering design multilayer attributed network_\(M=\left(V_{M},E_{M},A,V,L\right)\). Then, to simplify computation, ERSA use the matrix \(A=\left[\mathbf{a}_{ij}\right]\), which represents the set \(V\times L=\left\{(v\in V,I\in L)\right\}\) encompassing all possible combinations of model-domain pairs in the engineering design multilayer attributed network, with \(a_{ij}\in\left\{u,f,t\right\}\). The matrix (5) shows the set \(V\times L=\left\{(v\in V,I\in L)\right\}\) encompassing all possible combinations of model-domain pairs. \[ \begin{bmatrix}\mathit{ConClUser}&\mathit{ConCFunc}&\mathit{ConCPhys}& \mathit{ConCProc}\\ \mathit{MathUUser}&\mathit{MathFunc}&\mathit{MathPhys}&\mathit{MathProc}\\ \mathit{CompUUser}&\mathit{CompMath}&\mathit{CompPhys}&\mathit{CompProc}\\ \mathit{ExpeUser}&\mathit{ExpeMath}&\mathit{ExpePhys}&\mathit{ExpeProc}\\ \end{bmatrix}  \tag{5}\]  
The matrix (6) illustrates the case where \(a_{ij}=u\). It indicates that the employed methodology incorporates the models \(\mathit{ConClUser}\), \(\mathit{ConCFunc}\), \(\mathit{ConCPhys}\), \(\mathit{ConCProc}\), \(\mathit{MathPhys}\), \(\mathit{CompPhys}\) and \(\mathit{ExpePhys}\). \[ \begin{bmatrix}1&1&1&0\\ 0&0&1&0\\ 0&0&1&0\\ 0&0&1&0\\ \end{bmatrix}  \tag{6}\]  
The matrix (7) depicts the case where \(a_{ij}=f\). It indicates that the frequency \(f\) for the models \(\mathit{ConClUser}\), \(\mathit{ConCFunc}\), \(\mathit{ConCPhys}\), \(\mathit{ConCProc}\), and \(\mathit{MathPhys}\) within the employed methodology is 1, while the frequency \(f\) for the models \(\mathit{CompPhys}\) and \(\mathit{ExpePhys}\) within the employed methodology is 2. \[ \begin{bmatrix}1&1&1&0\\ 0&0&1&0\\ 0&0&2&0\\ 0&0&2&0\\ \end{bmatrix}