# A Comprehensive Literature Review on Hydrogen Tanks: Storage, Safety, and Structural Integrity
## 4 Systematic Literature Review Methodology
### Bibliographic Analysis
\begin{table}
\begin{tabular}{l c} \hline \hline
**Most Cited References** &
\begin{tabular}{c} **Total** \\ **Citations** \\ \end{tabular} \\ \hline [PERSON] ET AL., BLAST WAVE FROM A HIGH-PRESSURE & \\ GAS TANK RIPTURE IN A FIRE: STAND-ALONE AND & 3 \\ UNDER-VEHICLE HYDROGEN TANKS (2015) [135] & \\ \hline [PERSON] ET AL., DESIGN OF A 70 MPA TYPE IV HYDROGEN & \\ STORAGE VESSEL USING ACCURATE MODELING TECHNIQUES & 3 \\ FOR DOME THICKNESS PREDICTION (2020)[141] & \\ \hline [PERSON] ET AL., EXPLOSION HAZARDS AND & 2 \\ EVALUATION (1983) [142] & \\ \hline [PERSON] ET AL., MICROMECHANISMS OF LOAD TRANSFER & \\ IN A UNDIRECTIONAL CARBON FIBRE-REINFORCED EPOXY & 2 \\ COMPOSITE DUE TO FIBRE FAILURES: PART 3. MULTICALE & \\ RECONSTRUCTION OF COMPOSITE BEHAVIOUR (2008) [143] & \\ \hline [PERSON], DEVELOPMENT OF METAL HYDRIDE BEDS & \\ FOR SORPTION CRYCOCOOLERS IN SPACE APPLICATIONS (2003) [144] & 2 \\ \hline [PERSON] ET AL., PRESSURE LIMIT OF HYDROGEN & 2 \\ SPONTANEOUS IGNITION IN A T-SHAPED CHANNEL (2013) [145] & 2 \\ \hline [PERSON] ET AL., RISK ASSESSMENT METHODOLOGY & 2 \\ FOR ONBOARD HYDROGEN STORAGE (2018) [146] & \\ \hline [PERSON] ET AL., FEASIBILITY OF INTEGRATED OPTICAL & \\ FIBRE SENSORS FOR CONDITION MONITORING OF COMPOSITE & 2 \\ STRUCTURES. PART I: COMPARISON OF BRAGG-SENSORS & \\ AND STRAIN GAUGES (2003) [147] & \\ \hline [PERSON] ET AL., LIQUID HYDROGEN FUEL TANKS FOR & \\ COMMERCIAL AVIATION: STRUCTURAL SIZING AND & 2 \\ STRESS ANALYSIS (2019) [44] & \\ \hline [PERSON] ET AL., EVALUATION OF STRUCTURAL INTEGRITY OF & \\ TYPE-III HYDROGEN PRESSURE VESSEL UNDER LOW-VELOCITY & 2 \\ CAR-TO-CAR COLLISION USING FINITE ELEMENT ANALYSIS (2016) [148] & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The 10 most cited references in the review collection. indicating the quantity. In particular, smaller bubbles represent one publication, while larger bubbles represent two. The color intensity is proportional to the total citations per year. The authors are arranged in descending order of relevance. The relevance of the analysis is assessed based on the number of publications within the specified time frame. Figure 6 presents the conceptual structure map of the research topics covered in this work. This figure illustrates the relationships between words based on the proportion of documents that use them as keywords, indicating their similarity [129]. The center of the research field is represented as the origin of the axes, which indicates the average position of all column profiles [129; 131]. The percentages on the Dim 1 (43.8%) and Dim 2 (27.34%) axes represent the data variation resulting from dimensionality reduction. The K-means algorithm identified four clusters, each shown in a different color. Purple refers to hydrogen storage tanks and safety technologies; blue denotes the filling related to the temperature rise; green covers fuel cell vehicles design and analysis; and red involves the design of hydrogen vessels. Figure 7 illustrates the social structure of the researched field through a co-authorship network, highlighting the associations between authors of the systematically collected documents in this review paper. Each author is mentioned using the format \"surname + first initial letters of their names\". The Kamada-Kawai network layout was used, and normalization was performed using the Salton index, with clustering performed using the Louvain algorithm. The thickness of the edges is proportional to the number of shared works between the connecting authors. The colors indicate the identified clusters of common co-authorship. Figure 7 is helpful to identify influential research groups and authors. In this case, [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] are identified as the most influential authors within the analyzed period. Figure 5: The scientific output of the top ten authors over time. The bubble size represents the number of documents published, with small bubbles indicating one publication and large bubbles indicating two.