We fitted a new method allowing to use some of the knowledge involved in ch
emico-physical models with neural networks. This method, we call model-base
d neural networks, needs the disposal of experimental measures, a fully det
ermined model (even approximate), and access to the state variables of the
system. Owing this, we are able to fundamentally include mathematical model
s, such as physico-chemical ones, in the learning phase of the network, in
order to improve its performances, although relying on experimental data. T
he method was successfully tested by using theoretical examples. It occurs
to be especially useful when experimental data are badly determined. (C) 20
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