Table 5.
Material | Feature Domain | Hyperparameters | ||
---|---|---|---|---|
L2 Regularization |
Sparsity Regularizatio |
Sparsity Proportion |
||
Metallic | Time (T2 group) | 2.277 × 10−5 | 7.108 × 10−5 | 0.3228 |
Frequency (F2 group) | 1.077 × 10−5 | 8.433 × 10−5 | 0.2026 | |
Time–Frequency (TF2 group) | 2.277 × 10−5 | 7.108 × 10−5 | 0.3228 | |
Ceramic | Time (T2 group) | 1.675 × 10−5 | 6.944 × 10−5 | 0.4743 |
Frequency (F2 group) | 1.320 × 10−5 | 4.897 × 10−5 | 0.546 | |
Time–Frequency (TF2 group) | 1.821 × 10−5 | 4.950 × 10−5 | 0.678 | |
Hybrid | Time (T2 group) | 2.228 × 10−5 | 2.824 × 10−5 | 0.332 |
Frequency (F2 group) | 1.625 × 10−5 | 4.365 × 10−5 | 0.391 | |
Time–Frequency (TF2 group) | 3.384 × 10−5 | 7.621 × 10−5 | 0.4227 |