Prediction of Residual Gas Content during Coal Roadway Tunneling Based on Drilling Cuttings Indices and BA-ELM Algorithm

Table 3

Selection of activation function.

Activation function	Hidden-layer node number	Average absolute error	Training time (s)
Sigmoidal	3	0.131	0.027
Sin	3	0.171	0.027
Hardlim	3	0.219	0.030