Figure 3.6 Extrapolation measure
weighting mechanism: (a) set of P
discrete measured points used for
training the ANN (in a two-
dimensional input space); (b)
continuous density function
(extrapolation measure 0≤ε≤1)
obtained by clustering the training
patterns with a set of C«P
hyperspherical clusters (k-mean
algorithm); (c) Extrapolation measure
weighting mechanism: competition
between an ANN kinetic model and a
safety (Monod type) kinetic model.
When ε is high (ANN is not
extrapolating) the ANN is used
preferentially. When ε is low (ANN is
extrapolating) the safety model is
preferred.
the total amount of product, purity of final product (which is related to costs in
downstream processing), and production costs. The economic goals of the process are
dictated ultimately by the market dynamics. Unlike many chemical processes, security is
usually not a major concern in bioprocess operation but sterility is. This is one of the
main reasons why bioprocess automation and control did not develop as much as in the
chemical industry. However the economic benefits could be considerable in many
production plants if proper control were in operation.
As stressed by Roy ce (1993), whilst for the different types of biochemical processes
and products different types of production costs are dominant, they all share the common
interest of improving process yield as a major economic benefit. The straightforward way
to improve process yield is investing in process control. Currently industrial production
plants are controlled manually and empirically which leads to slow process improvement.
Three major advantages should be expected from the implementation of automation and
control:
- Faster adapting and enforcing of new optimum whenever the process is changed (e.g.,
new strain or new media). - Faster adapting and enforcing of new optimum related to new market demands.
- Releasing of staff that might concentrate on more relevant tasks.
It also is relevant to stress that strain development, medium optimisation and process
control are all important issues contributing to economic benefits and that complement
themselves. For instance, tests for comparing strain productivity in production conditions
New methodologies for multiphase bioreactors 3 77