This payer addresses methods of knowledge engineering for chemical and bioc
hemical process modelling and control. The concept of knowledge Based Modul
ar (KBM) Networks is presented. KBM networks represent a method of expressi
ng and combining different types of knowledge usually available for modelli
ng chemical and biochemical processes: mechanistic, heuristic and knowledge
hidden in process data records, The Expectation Maximisation (EM) algorith
m is employed to optimally combine the modules within the KBM network. The
concepts are illustrated with an application to a baker's yeast production
process. The results show that it is possible to obtain more accurate proce
ss description when all available sources of knowledge are incorporated in
the process model. (C) 2001 Elsevier Science Ltd. All rights reserved.