## 4 Results
### Use Case #1: CVT Failure Events' Prediction Results  
Residual histograms were calculated according to Section 2.2.3, with 1024 bins per sample. Figure 4 shows array-based metric values using residual histograms generated every five, ten, thirty, and sixty minutes, cross-correlated with the corresponding interval's reference residual histogram. The array-based metric measures the similarity between the reference histogram and those generated from the storage sampled waveform(s). Figure 4 presents the average of each array-based metric for residual histograms generated every five, Figure 4a, ten, Figure 4b, thirty, Figure 4c, and sixty, Figure 4d, minutes. The array-based metric for the residual histograms generated every five minutes, Figure 4a, provides inconsistent (i.e., the value varies from 0.4 to 0.9) actionable information (a.k.a., prediction of CVT failure) 1 h before the first DFR-triggering CVT failure. The array-based metric becomes more consistent, approaching the first CVT event at 18 h and remaining consistent throughout the processing period. There is one drop in the array-based metric value, approximately 12 h before the last DFR-triggering CVT failure event. However, the noisy nature of the metric using the five-minute interval residual histograms may make it difficult to set a threshold or another measure that consistently predicts CVT failure before the DFR is triggered. Figure 4b shows the array-based metric for residual histograms generated every ten minutes. As in Figure 4a, CVT failure prediction is inconsistent 1 hour before the first DFR-triggering CVT failure event but becomes and remains relatively consistent afterward. Here, the metric is noisy and suffers a drop around 16 h before the last DFR-triggering CVT failure event. This drop and relatively long recovery may also make it difficult to set a threshold or measurement that consistently predicts CVT failure before the DFR is triggered. The array-based metric for thirty-minute-generated residual histograms is shown in Figure 4b. The behavior is inverted when compared to the five-, ten-, and sixty-minute interval results shown in Figure 4a-d, respectively. Again, the array-based metric is inconsistent for the first four hours (i.e., 24 to 20 h before the first recorded CVT failure event), thus limiting its IFP value. The array-based metric value does become more consistent after the first four hours but does not predict any of the CVT failure events before the DFR is triggered, thus negating its IFP potential. Figure 4d shows the array-based metric for the residual histograms generated every sixty minutes. The metric is consistently low before the first DFR-triggering CVT failure event that occurs 18 h before the third and final event. The array-based metric's value reaches 0.99 (a.k.a., high similarity) one hour before the first CVT failure event triggers the DFR, and the value is higher than 0.95 for the remaining processing period, except for the low value a little under 12 h before the final event. It is important to note that the array-based metric is high (i.e., above 0.98) at least one hour before all three CVT failure events trigger the DFR, thus providing IFP-actionable information. Additionally, the residual histograms generated every sixty minutes have the lowest memory requirements compared to the other three time intervals and unprocessed waveforms. The cross-correlation values presented in Figure 4 are calculated using the reference residual histogram generated using the OSG data corresponding to the DFR's last (a.k.a., most recent) triggering CVT failure event, designated as \"zero hour\" in Figure 4. The CVT failure events occurring eighteen and three hours before the last DFR-triggering CVT failure event are considered \"blind tests\" of the presented IFP approach. The high CVT failure likelihood value (i.e., a cross-correlation value above 0.9) one hour before the DFR-triggering CVT failure event occurs at hour eighteen, showing the viability of the presented cross-correlation-based IFP approach.