## 3 Experimental Results
### Dimensionality Reduction Preprocessing of Time Domain and Frequency Domain Feature Parameters
For the initial time period \(t\) = 0, each device is completely reliable, that is, the prior probability of the root node is one. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{2}{c}{**Frequency Domain**} & \multirow{2}{*}{**Normal**} & \multirow{2}{*}{**Failure**} & \multicolumn{2}{c}{**Distance Evaluation**} \\ \multicolumn{2}{c}{**Characteristic Parameters**} & & & **Factor** \\ \hline \multirow{3}{*}{P1} & 308.6667 & 368.2122 & \multirow{3}{*}{0.2661} \\  & 769.4345 & 934.4990 & & \\  & 459.4171 & 533.5448 & & \\ \hline \multirow{3}{*}{P2} & 23,016.8406 & 145,680.8745 & \multirow{3}{*}{1.0694} \\  & 222,145.9256 & 1,029,877.5849 & & \\  & 69,255.5283 & 248,311.4071 & & \\ \hline \multirow{3}{*}{P3} & 0.3389 & \(-\)0.3178 & \multirow{3}{*}{2.3919} \\  & 1.8584 & \(-\)0.1908 & & \\  & 1.1854 & \(-\)0.1857 & & \\ \hline \multirow{3}{*}{P4} & 2.9644 & 8.7022 & \multirow{3}{*}{0.1371} \\  & 10.0102 & 7.2467 & & \\  & 4.7948 & 3.4943 & & \\ \hline \multirow{3}{*}{P5} & 1266.6140 & 1163.7718 & \multirow{3}{*}{0.0011} \\  & 2512.4981 & 2348.9416 & & \\ \cline{1-1}  & 3746.0745 & 3487.8604 & & \\ \hline \multirow{3}{*}{P6} & 1266.6140 & 1163.7718 & \multirow{3}{*}{0.0010} \\  & 2512.4981 & 2348.9416 & & \\ \cline{1-1}  & 3746.0745 & 3487.8604 & & \\ \hline \multirow{3}{*}{P7} & 1192.0432 & 1152.3006 & \multirow{3}{*}{0.0010} \\  & 2575.5760 & 2592.5181 & & \\ \cline{1-1}  & 3728.0676 & 3575.9603 & & \\ \hline \multirow{3}{*}{P8} & 7.3577 & 4.2680 & \multirow{3}{*}{0.0658} \\  & 2.2600 & 2.2534 & & \\ \cline{1-1}  & 21.5917 & 21.7248 & & \\ \hline \multirow{3}{*}{P9} & 3854.9987 & 1581.6570 & \multirow{3}{*}{2.6607} \\  & 6309.6179 & 2441.5379 & & \\ \cline{1-1}  & 4478.0834 & 1992.5765 & & \\ \hline \multirow{3}{*}{P10} & 3.0380 & 1.2276 & \multirow{3}{*}{1.5447} \\  & 2.6595 & 1.0377 & & \\ \cline{1-1}  & 1.2127 & 0.5349 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Each frequency domain characteristic parameter value and distance evaluation factor under different running conditions. The reliability of the system is measured by the instantaneous availability of the system through the forward inference of the DBN. The specific process is as follows:  
1. According to the failure rate and repair rate of the equipment in Tables 2 and 10, the state transition table of the root node in the DBN with maintenance during the voyage can be obtained. 2. According to the failure rate and maintenance rate of the equipment in Tables 3 and 10, the state transition table of the root node in the DBN without maintenance during the voyage can be obtained. 3. The obtained state transition table with or without maintenance during navigation is substituted into the root node, and the running time is set. The instantaneous availability change of the system can be obtained by running the DBN model. The transient availability of the ship's marine oil system with and without maintenance during the voyage is shown in Figure 8. It can be seen that the instantaneous availability \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Device ID** & \(\mathbf{\lambda_{1}}\) **(Failures/h)** & \(\mathbf{\lambda_{2}}\) **(Failures/h)** & \(\mathbf{\lambda_{3}}\) **(Failures/h)** & \(\mathbf{\mu_{1}}\) **(Repairs/h)** & \(\mathbf{I}\) & \(\mathbf{D}\) \\ \hline MP & \(63.08\times 10^{6}\) & \(33.40\times 10^{6}\) & \(19.10\times 10^{6}\) & 0.0105 & 0.10 & 0.60 \\ \hline CP & \(38.78\times 10^{6}\) & \(9.62\times 10^{6}\) & \(27.08\times 10^{6}\) & 0.0505 & 0.05 & 0.80 \\ \hline SP & \(24.71\times 10^{6}\) & \(18.54\times 10^{6}\) & \(32.75\times 10^{6}\) & 0.0180 & 0.15 & 0.65 \\ \hline RV & - & - & \(1.16\times 10^{6}\) & 0.0297 & - & - \\ \hline HE & - & - & \(0.15\times 10^{6}\) & 0.0263 & - & - \\ \hline PP & - & - & \(2.52\times 10^{6}\) & 0.0604 & - & - \\ \hline AM & - & - & \(5.00\times 10^{6}\) & 0.0208 & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Reliability data. Figure 7: Fault tree of ship oil system.