Research Article
Study on the Noise Reduction of Vehicle Exhaust NOX Spectra Based on Adaptive EEMD Algorithm
Table 4
Absorbance and inverted concentrations before and after noise reduction with three algorithms.
| | NO2/NO:300/786 ppm, λ = 226.5 nm, L = 100 cm | Theoretical absorbance | Before noise reduction | Concentration before denoising | After noise reduction | Concentration after denoising |
| | EMD LPF | 0.6028 | 0.6329 | 314.9/825.5 ppm | 0.3360 | 169.3/439.2 ppm | | Wavelet | 0.5782 | 287.8/753.9 ppm | | NIO EEMD | 0.5988 | 298.3/780.8 ppm |
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