Fig. 1. Different algorithms applied in terahertz spectroscopy

Fig. 2. Calibration and validation results for water content prediction using KPLS models^[26].(a) Established by the transmission spectra; (b) established by the absorption spectra

Fig. 3. LOOCV-SVR prediction for BSA with various concentrations in the range from 0.5 to 35 mg/mL. (a) Distributions of actual and predicted concentrations, the valid value of horizontal axis is from 1 to 135 and represents 135 spectral measurement values; (b) actual concentrations against predicted concentrations

Fig. 4. The spectra of mixture made by L-Glu, D-MI, GABA and CMH^[40].(a) Experimental results of mixture; (b) comparison between experiment result and calculation result

Fig. 5. Score plot of the first two principle components for the EAE and normal monkey brain tissues^[53]

Fig. 6. Terahertz absorption spectra of ten mixture samples^[61]; (a) Original spectra; (b) spectra after wavelet transform; (c) spectra after baseline correction by polynomial fitting