Figure 4

Scatter plots of prediction results for carbon content (a), O/C (b), and H/C (c) by PLSR models trained with second-derivative NIR spectra. R2c coefficient of determination for calibration, R2p coefficient of determination for prediction.

Scatter plots of prediction results for carbon content (a), O/C (b), and H/C (c) by PLSR models trained with second-derivative NIR spectra. R2c coefficient of determination for calibration, R2p coefficient of determination for prediction.