A soft sensor model based on long&short-term memory dual pathways convolutional gated recurrent unit network for predicting cement specific surface area.

The specific surface area of cement is an important index for the quality of cement products. But the time-varying delay, non-linearity and data redundancy in the process industry data make it difficult to establish an accurate online monitoring model. To solve the problems, a soft sensor model based on long&short-term memory dual pathways convolutional gated recurrent unit network (L/S-ConvGRU) is proposed for predicting the cement specific surface area. In this paper, first, as the linear coupling constraint inside the gated recurrent unit network (GRU) hinders the flow of information, parameters L and S are introduced into convolutional gated recurrent unit network (ConvGRU). L and S are decimals in the range (0, 1) which changed its internal linear constraint relationship and enhanced the feature extraction capability of the model. Then, two spatio-temporal feature extraction pathways are designed: long-term memory enhancement pathway and short-term dependence pathway, which capture long-term and short-term time-varying delay information from the sample data. Finally, the two feature extraction pathways mentioned above are applied to the L/S-ConvGRU model and the extracted spatio-temporal features are fused to achieve accurate prediction of the specific surface area of cement. The model was trained using raw data from the cement plant and the experimental results show that L/S-ConvGRU has higher precision and better generalization capability.