Network Structures. Delay TF-A transcription model. (A) true network structure (B) DDEHM network without prior knowledge, (C) DDEHM network with some prior knowledge. In structures (B) and (C), the ANN comprises three layers. The nodes of the input and output layer have linear transition functions, except for the input node of the time which has a hyperbolic tangential transition function as do the nodes of the hidden layer.