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Experimental and simulation studies of multivariable adaptive optimization of continuous bioreactors using bilevel forgetting factors
Author(s) -
Chang Yong K.,
Lim Henry C.
Publication year - 1989
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260340502
Subject(s) - bioreactor , dilution , adaptability , multivariable calculus , optimization problem , control theory (sociology) , mathematics , mathematical optimization , computer science , chemistry , engineering , thermodynamics , physics , ecology , control (management) , organic chemistry , control engineering , artificial intelligence , biology
A multivariable on‐line adaptive optimization algorithm using a bilevel forgetting factor method was developed and applied to a continuous baker's yeast culture in simulation and experimental studies to maximize the cellular productivity by manipulating the dilution rate and the temperature. The algorithm showed a good optimization speed and a good adaptability and reoptimization capability. The algorithm was able to stably maintain the process around the optimum point for an extended period of time. Two cases were investigated: an unconstrained and a constrained optimization. In the constrained optimization the ethanol concentration was used as an index for the baking quality of yeast cells. An equality constraint with a quadratic penalty was imposed on the ethanol concentration to keep its level close to a hypothetical “optimum” value. The developed algorithm was experimentally applied to a baker's yeast culture to demonstrate its validity. Only unconstrained optimization was carried out experimentally. A set of tuning parameter values was suggested after evaluating the results from several experimental runs. With those tuning parameter values the optimization took 50–90 h. At the attained steady state the dilution rate was 0.310 h −1 the temperature 32.8°C, and the cellular productivity 1.50 g/L/h.