Corynebacterium glutamicum - JUWEL - Forschungszentrum Jülich

4. Simulative Comparison of Model Discriminating Design Criteria
Similar to in the first case study, the difference between the expected model variances is
determining the experiment to a much larger extend than the differences in the expected
concentrations. The part of the criterion, driven by the model variances, accounts for
99.5% of the criterion.
The BH criterion is calculated as a summation over all measured values and all model
pairs. The criterion for each state variable and each measured point is shown in figure
4.10(c) for each model pair.
As could be expected from figure 4.10, mainly the differences between model Cat2
and the other two models are of influence. Furthermore, it is mainly the measurement
of substrate which contributes to the criterion. Especially the measurements in a range
where one of the models from a model pair predicts very low substrate concentrations
are of importance.
Buzzi-Ferraris and Forzatti (BF)
The designed experiment according to the BF criterion is shown in figure 4.11, illustrated
by the expected concentrations according to the competing models. Again, skipped
samples are caused by the lower bound on the volume.
In this experiment, the influence of the different model pairs is more evenly divided:
model pairs Cat1-Cat2, Cat1-Cat3 and Cat2-Cat3 accounted for about 27%, 18% and
56% of the criterion.
The criterion was with 2 · 10 4 by far high enough to pass the minimal value according
to the original BF criterion.
Chen and Asprey (CA)
The designed experiment according to the CA criterion is shown in figure 4.12, illustrated
by the expected concentrations according to the competing models.
In this designed experiment, the model pairs Cat1-Cat2, Cat1-Cat3 and Cat2-Cat3
accounted for 28%, 24% and 48% of the criterion. In this case, the optimized criterion
was with 5·10 4 high enough not to have problems regarding the minimal value suggested
in the original criterion.
The criterion is shown over time for substrate and product in figure 4.12(c), showing
that 98% of the criterion is accounted for by the substrate measurements, fairly evenly
divided over time.
Hunter and Reiner (HR)
The designed experiment according to the HR criterion is shown in figure 4.13, illustrated
by the expected concentrations according to the competing models. Obviously, the
suggested experiment is very similar to the experiment according to the CA criterion
shown in the prior paragraph.
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