## 3 Results
### Systematic Content Review Results for Sensors Monitoring Mine Tailings Storage Facilities
#### 3.3.1 Content-Based Data Perspective Analysis
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**\#** & **Reference** & **\#** & **\#** & **\#** & **\#** & **\#** & **\#** & **\#** & **\#** \\ \hline
34 & [PERSON] et al. [89] & 2013 & OS & RTA & 4G & RL & C & C & NS & NS \\
35 & [PERSON] et al. [46] & 2017 & R & RTA & S & D & G & W & IoT & NS \\
36 & [PERSON] et al. [34] & 2020 & R & RTA & Z & D & G & W & IoT & Y \\
37 & [PERSON] et al. [90] & 2019 & R & RTA & S & D & G & W & NS & NS \\
38 & [PERSON] et al. [91] & 2019 & OS & RTA & 4G & RL & M & W & AI & NS \\
39 & [PERSON] et al. [45] & 2012 & R & RTA & S & D & G & W & CC & NS \\
40 & [PERSON] et al. [92] & 2014 & OS & RTA & Z & D & M & W & IoT & NS \\
41 & [PERSON] [33] & 2020 & OS & RTA & NS & RL & M & NS & AI & NS \\
42 & [PERSON] et al. [93] & 2020 & R & RTA & S & D & G & W & NS & NS \\
43 & [PERSON] et al. [94] & 2020 & OS & RTA & 4G & D & G & W & IoT & NS \\
44 & [PERSON] and [PERSON] [4] & 2023 & R & RTA & S & RL & C & W & CC & NS \\
45 & Haiming and Jing [95] & 2013 & R & RTA & 4G & D & C & NS & NS & NS \\
46 & [PERSON] et al. [96] & 2011 & OS & RTA & 4G & D & G & C & NS & NS \\
47 & [PERSON] et al. [35] & 2012 & OS & RTA & 4G & D & C & W & IoT & NS \\
48 & [PERSON] et al. [97] & 2019 & R & RTA & S & D & M & W & NS & Y \\
49 & [PERSON] et al. [98] & 2022 & OS & RTA & 4G & D & M & W & IoT & NS \\
50 & [PERSON] [99] & 2021 & R & RTA & S & D & G & W & IoT & NS \\
51 & [PERSON] et al. [100] & 2021 & R & RTA & S & D & M & W & NS & NS \\
52 & [PERSON] et al. [32] & 2023 & R & RTA & Z & RL & C & W & IoT & NS \\ \hline \hline \end{tabular}
\end{table} 
Table 5: _Cont._* Regarding the technologies linked to Industry 4.0, 23% of the cases are not specified. However, 21% of the cases mention AI, 17% mention the IoT, 13% mention CC, and 25% mention other technologies. This shows that sensor systems are often linked to AI and IoT approaches, but massive integration with other Industry 4.0 technologies such as digital twins (DT) remains lacking. * The cost analysis reveals that, although all applications claim to reduce costs, this characteristic is rarely documented in the scientific literature. TSF monitoring processes have varied from manually measuring dams and the installation of downhole instrumentation to measuring pore pressures or monitoring crack structures. Typically, these activities are periodically undertaken via manual techniques that require humans in the field, increasing the risk of fatigue or injury [34]. Furthermore, as mining projects grow, surveying crews are inevitably placed under more operational pressure and routine monitoring tasks can bear the risk of accidents [32]. Alternatives to manual methods include the application of a wireless, autonomous, near-real-time monitoring system with sensors that avert the need to manually measure relevant parameters [37]. Furthermore, the cost to the operation, whilst higher in the short term with CAPEX, is rapidly offset by the minimal labor and data transfer effort required. The benefits of wireless systems are primarily associated with the ease of installation. New communication technologies preserve the data pathways between the sensors, and only part of the system must be able to see the gateway [101]. Once installed, work activities around the system are facilitated by the absence of cabling, and temporary obstructions can be resolved by the system's ability to self-heal data pathways from the instruments to the gateway [101]. Near-real-time systems can alert key personnel when TSF thresholds are exceeded or sensors have been disconnected from the gateway for a short time. For example, tilt systems can be integrated with other geotechnical and downhole instrumentation, allowing the entire system to report to a dashboard. In situ, pore pressures within a dam can be measured with a vibrating wire piezometer and the data can be wirelessly collected by a single gateway in the field. Instruments that are further afield, such as crack sensors and displacement sensors, can also be integrated.