## 4 Case Study: Application of the Modified FMEA-DEA for the RFID System
### Rating and Aggregating the Failure Modes (Steps 1.4-1.10)  
Based on data provided by experts (Supplementary Material), the total number of the identified failure modes (FMs) is \(M=43\), with a total number of sub-failure modes (SFMs) of \(N=67\); the number of sub-failure modes \(n_{i}\) related to each parent failure mode are depicted in Table 2; the rating scale for each sub-failure mode against each risk factor is from one to five. The number of experts participating in the risk assessment is \(T=5\); the teams consist of groups of experts and not individuals. Hence, there was insufficient evidence to highlight significant differences among FMEA team members regarding their assessment \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{**Failure Modes (FMs)**} & \multicolumn{2}{c}{**Cause (s) of Failure (Sub-Failure Modes SFMs)**} & \multicolumn{2}{c}{**Effects**} \\ \hline \multirow{4}{*}{34} & \multirow{4}{*}{Failure to receive signals by the tag or reader.} & \multirow{4}{*}{4} & \multirow{4}{*}{1} & \multicolumn{2}{c}{Defective sensitivity detection of the tag or the reader.} \\ \cline{5-6}  & & & & 2 & Electromagnetic field disturbances. \\ \cline{5-6}  & & & & 3 & External aggression affecting the antennas in the tag or the reader. \\ \cline{5-6}  & & & & 4 & Internal failure in the reader. \\ \cline{5-6}  & & & & 1 & Internal failure in the tag. \\ \cline{5-6}  & & & & 2 & Repetitive software attempts to communicate. \\ \cline{5-6}  & & & & 1 & Interior failure in the tag \\ \cline{5-6}  & & & & 2 & Interior failure in the reader \\ \cline{5-6}  & & & & 3 & Repetitive trials to communicate by the software \\ \hline \multirow{4}{*}{37} & \multirow{4}{*}{Failure to receive and reader.} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & Unfavorable environmental conditions (metallic, liquid, etc.).} & \multirow{4}{*}{Loss of information} \\ \cline{5-6}  & & & & & & \\ \cline{5-6}  & & & & & & \\ \cline{5-6}  & & & & & & \\ \cline{5-6}  & & & & & & \\ \cline{5-6}  & & & & & & \\ \cline{5-6}  & & & & & & \\ \hline \multirow{4}{*}{38} & \multirow{4}{*}{Failure to receive and reader.} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & Inadequate or ineffective protective measures/tools.} & \multirow{4}{*}{Breathes in users’ privacy and security.} \\ \cline{5-6}  & & & & Software bugs & 1 & 1 & Ignorance, big data, slow system & Incorrect, duplicate and missed reading \\ \cline{5-6}  & & & & & & Weak or faulty connection between the reader and the host (Wi-Fi/serial interface/Bluetooth, etc.). & The host fails to receive data and does not transmit information to the tag. \\ \cline{5-6}  & & & & & & Interface/Bluetooth, etc.). & Unauthorized access, compromised functionality, or system malfunction. \\ \hline \multirow{4}{*}{42} & \multirow{4}{*}{Failure to receive and reader.} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & Unfavorable specification ratio (SAR) of the human head, surpassing 1.6, which is the maximum value permitted by the FCC in the US.} \\ \cline{5-6}  & & & & & & & \\ \cline{5-6}  & & & & & & \\ \cline{5-6}  & & & & & & \\ \hline \multirow{4}{*}{43} & \multirow{4}{*}{Failure to receive and reader.} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & \multirow{4}{*}{1} & Evaluation and use of rare metals \\ \cline{5-6}  & & & & & & & \\ \cline{5-6}  & & & & & & & \\ \cline{5-6}  & & & & & & & \\ \cline{5-6}  & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._capabilities; therefore, we assumed an equal weight \(\lambda_{e}=1/5\) for all team members. The outcomes of the aggregation of risk factor ratings are presented in detail in Appendix C. Table 3 presents the failure modes with sub-failure modes, as well as the ranking gaps among the latter.