Fig. 1. Modeling flow diagram of transfer learning algorithm

Fig. 2. Process flow diagrams and Reactive principle sketch
(a): Process flow diagram; (b): Reactive principle sketch

Fig. 3. Spectral comparison at different detecting points

Fig. 4. Different principal component numbers impact on model performance

Fig. 5. Different sample numbers of dephenolization tower impact on model performance
(a): Impact on model performance for transferring different sample numbers of dephenolization tower;(b): Model performance improvement percentage for transferring different sample numbers of dephenolization tower

Fig. 6. Different sample numbers of o-cresol tower impact on model performance
(a): Impact on model performance for transferring different sample numbers of o-cresol tower;(b): Model performance improvement percentage for transferring different sample numbers of o-cresol tower

Fig. 7. Model curve and Scatter plot
(a): Model curve; (b): Scatter plot of prediceted and actual values