title: Hybrid filtering to rescue stable oscillations from noise-induced chaos in continuous cultures of budding yeast.
abstract: In large-scale fermentations with oscillating microbial cultures, noise is commonly present in the feed stream(s). As this can destabilize the oscillations and even generate chaotic behavior, noise filters are employed. Here three types of filters were compared by applying them to a noise-affected continuous culture of Saccharomyces cerevisiae with chaotic oscillations. The aim was to restore the original noise-free stable oscillations. An extended Kalman filter was found to be the least efficient, a neural filter was better and a combined hybrid filter was the best. In addition, better filtering of noise was achieved in the dilution rate than in the oxygen mass transfer coefficient. These results suggest the use of hybrid filters with the dilution rate as the manipulated variable for bioreactor control.
authors.affiliation: Institute of Microbial Technology, Chandigarh, India. pratap@imtech.res.in
authors.forename: Pratap R
authors.initials: PR
authors.lastname: Patnaik
mesh_terms: D019149:Bioreactors; D003470:Culture Media; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D007218:Industrial Microbiology / Q000379:methods*; D008954:Models, Biological; D016571:Neural Networks, Computer; D009622:Noise; D017711:Nonlinear Dynamics; D009991:Oscillometry; D012441:Saccharomyces cerevisiae / Q000254:growth & development*; D012815:Signal Processing, Computer-Assisted
chemical_list: D003470:Culture Media; D000431:Ethanol