## 4 Materials and Methods
### Feature Factor Selection  
Based on the previous phenomenon description and analysis, the factors influencing short-period characteristics include temperature, load current, and MEA. The Pearson Correlation Coefficient is used to analyze the correlation of each factor. This coefficient measures the linear correlation degree between two variables, with values ranging from \([-1,1]\). A value of 1 indicates a perfect positive correlation, \(-1\) indicates a perfect negative correlation, and 0 indicates no linear correlation. The following are its calculation formula and related explanations:  
Assume two variables X and Y with a sample size of n, and their corresponding observation values are \((x_{1},y_{1}),(x_{2},y_{2}),\ldots,(x_{n},y_{n})\). The Pearson correlation coefficient r is calculated as  
\[r=\frac{\sum_{i=1}^{n}(x_{i}-\overline{x})(y_{i}-\overline{y})}{\sqrt{\sum_{i= 1}^{n}(x_{i}-\overline{x})^{2}}\sqrt{\sum_{i=1}^{n}(y_{i}-\overline{y})^{2}}} \tag{7}\]  
\[\overline{x}=\frac{1}{n}\sum_{i=1}^{n}x_{i} \tag{8}\]  
\[\overline{y}=\frac{1}{n}\sum_{i=1}^{n}y_{i} \tag{9}\]  
The correlation results between each factor are shown in Table 7 below:  
From the above table, the following conclusion can be drawn:  
For satellites with normal solar array drives, the following applies:  
Temperature exhibits low correlation with short-period characteristics and can be excluded. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Parameters** & \multicolumn{2}{c}{**Load Current**} & \multicolumn{2}{c}{**Solar Array +Y Output**} & \multicolumn{2}{c}{**Solar Array \(-\)Y Output**} \\  & & & **Current** & & **Current** & \\ \hline  & **Normal** & \(-\)**Y Fails** & **Normal** & \(-\)**Y Fails** & **Normal** & \(-\)**Y Fails** \\ MEA & \(-\)0.9240 & \(-\)0.1026 & 0.7795 & 0.9614 & 0.7406 & 0.9701 \\ +Y wing temperature 1 & 0.0410 & 0.0824 & 0.0064 & 0.8978 & \(-\)0.1084 & 0.9350 \\ (PC1 temperature) & \(-\)0.3316 & 0.1314 & 0.3439 & 0.5162 & 0.2160 & 0.5243 \\ +Y wing temperature 3 & \(-\)0.6253 & 0.0262 & 0.4423 & 0.8854 & 0.5576 & 0.8540 \\ (PC7 temperature) & \(-\)0.0819 & 0.0304 & 0.2226 & 0.8416 & 0.0524 & 0.8648 \\ \(-\)Y wing temperature 1 & \(-\)0.4319 & 0.0242 & 0.1040 & 0.7894 & \(-\)0.0191 & 0.8127 \\ 2(PC8 temperature) & \(-\)0.069 & 0.0268 & 0.3172 & 0.7713 & 0.3370 & 0.7952 \\ (PC10 temperature) & \(\backslash\) & \(\backslash\) & \(-\)0.8235 & \(-\)0.2918 & \(-\)0.8821 & \(-\)0.1123 \\ Solar array \(-\)Y & \(\backslash\) & \(\backslash\) & 0.7633 & 0.9209 & \(\backslash\) & \(\backslash\) \\ output current & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Correlation analysis results. Although the MEA parameter shows high correlation with the short-period characteristics of solar array current, it is also highly correlated with load current. Considering that load current is directly linked to the short-period fluctuations of solar array current (\(|\)r\(|\) = 0.88) with a clearer physical meaning, this feature is retained while the MEA parameter is excluded to avoid information redundancy. For satellites with single-wing solar array failures [46]:  
1. Time-phase factors reflecting the orbital period characteristics of the faulty wing's output current must be retained. The \"time phase\" reflecting orbital periodicity is derived from raw telemetry timestamps, with integration of time intervals to capture orbital periodicity. Specifically, instead of using sine/cosine transformations of orbital angles or discrete bin indices, we directly compute the time difference (\(\Delta\)t) between each telemetry point and the initial telemetry point (i.e., the first sampled telemetry point) is calculated directly based on the original timestamps. This \(\Delta\)t is used as a core input feature; as domestic and overseas telemetry adopt 1 s and 60 s intervals, respectively, we avoid interpolation or resampling. Instead, the \(\Delta\)t values are fed directly into the model as a feature, allowing the algorithm to learn the impact of sampling frequency differences on current output. 2.