Research Article
Study on the Noise Reduction of Vehicle Exhaust NOX Spectra Based on Adaptive EEMD Algorithm
Table 1
SNR of NOX spectra of different concentrations before and after denoising.
| | Gas | Absorption
length | Sample gas
concentration | SNR/dB | SNR′/dB |
| | NO | 40 cm | 16 ppm | 17.5626 | 25.5619 | | NO | 40 cm | 1572 ppm | 19.1573 | 24.3398 | | NO | 100 cm | 16 ppm | 18.2774 | 26.1679 | | NO | 100 cm | 1310 ppm | 19.1125 | 26.0135 | | NO2 | 40 cm | 25 ppm | 16.3378 | 25.7757 | | NO2 | 40 cm | 500 ppm | 18.9986 | 25.3589 | | NO2 | 100 cm | 25 ppm | 18.4318 | 24.4095 | | NO2 | 100 cm | 300 ppm | 19.8761 | 27.0057 | | NO2/NO | 100 cm | 100/1310 ppm | 23.0499 | 28.9197 | | NO2/NO | 100 cm | 200/1048 ppm | 22.8761 | 28.1918 | | NO2/NO | 100 cm | 300/786 ppm | 22.0731 | 28.1347 | | NO2/NO | 100 cm | 500/262 ppm | 21.7682 | 27.6987 |
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