Figure 5 Performance of ANN model with a variable number of neurons in the second hidden layer. (a) R; (b) MSE
The final architectural diagram of the selected ANN model is shown in Figure 6 with 8 inputs, five neurons for the first hidden layer and 7 for the second. The improvement in performance of the ANN model during the training, validating and testing processes is illustrated in Figure 7. At the epoch 19th, the best validation performance was reached while the training performance still improved after epoch 19th.