Extrusion process by Laurent Dewasme
A Review of Dynamic Models of Hot-Melt Extrusion
Processes, 2016
Fermentation process by Laurent Dewasme
Abstract: Nowadays, on-line bioprocess monitoring is still a delicate task due to the lack of on-... more Abstract: Nowadays, on-line bioprocess monitoring is still a delicate task due to the lack of on-line measurements of the key components of a culture. In this study, the use of artificial neural networks (NNs) as a basis to develop software sensors is investigated. Particularly, attention is focused on the use of standard signals, such as those coming from pH or oxygen regulation, to infer information on the evolution of biomass or products of yeast and bacteria fed-batch cultures.
Abstract: In this study, we consider the problem of optimizing the productivity of fed-batch cult... more Abstract: In this study, we consider the problem of optimizing the productivity of fed-batch cultures of S. cerevisiae, which are characterized by strongly nonlinear kinetic models based on the bottleneck assumption of Sonnleitner and Käppeli [1986] and ethanol inhibition resulting from the fermentation of a possible excess of substrate feeding.
Abstract: Optimizing control of E. coli cultures depends on the availability of appropriate on-li... more Abstract: Optimizing control of E. coli cultures depends on the availability of appropriate on-line sensors for the main culture components. A simple and efficient approach to maintain E. coli cultures in the neighborhood of the optimal operating conditions is to regulate the byproduct (ie, acetate) concentration at a constant low level. Unfortunately, reliable acetate probes are currently not available on the market, and it is necessary to design a software sensor.
Abstract: This work proposes a robust control strategy for the optimizing control of fed-batch cu... more Abstract: This work proposes a robust control strategy for the optimizing control of fed-batch cultures of S. cerevisae. The process dynamics is characterized by a nonlinear kinetic model based on the bottleneck assumption and ethanol inhibition for a possible excess of substrate feeding. The control strategy is based on the feedback linearization technique, where the resulting free linear dynamics is designed so as to ensure a certain robustness to plant parameter variations.
Abstract: Optimizing control of E. coli cultures depends on the availability of appropriate on-li... more Abstract: Optimizing control of E. coli cultures depends on the availability of appropriate on-line sensors for the main culture components. A simple and efficient approach to maintain E. coli cultures in the neighborhood of the optimal operating conditions is to regulate the byproduct (ie, acetate) concentration at a constant low level. Unfortunately, reliable acetate probes are currently not available on the market, and it is necessary to design a software sensor.
In this paper, experimental investigations of an adaptive RST control scheme for the regulation o... more In this paper, experimental investigations of an adaptive RST control scheme for the regulation of the ethanol concentration in fed-batch cultures of S. cerevisiae is presented. Our main objective is to prove efficiency and robustness of this controller in experimental applications ranging from laboratory to industrial scales. The controller only requires one on-line measurement signal, making it easily implementable in an industrial environment. Disturbance rejection is ensured thanks to an on-line parameter adaptation procedure, which delivers as a side product an estimate of the growth rate that can be used for process monitoring purposes. The robustification of the controller is achieved in a simple way, using the observer polynomial.
In this paper, two robust RST control schemes for the regulation of either the ethanol concentrat... more In this paper, two robust RST control schemes for the regulation of either the ethanol concentration or the dissolved oxygen concentration in cultures of S. cerevisae are presented and illustrated with various simulation and experimental results. Both controllers only require the prior knowledge about one stoichiometric coefficient and only one on-line measurement signal, making them easily implementable in an industrial environment. Disturbance rejection is ensured thanks to an on-line parameter adaptation procedure, which delivers as a side product an estimate of the growth rate that can be used for process monitoring purposes. The robustification of the controllers is achieved in a simple way, using the observer polynomial. Additional issues, such as the presence of a delay in the system response (as observed in real-life experiments) or non negligible sensor dynamics, are also addressed.
A simple design procedure for robust adaptive control of yeast fed-batch culture
From an economical point of view, one of the technical chal-lenges is to optimize biomass product... more From an economical point of view, one of the technical chal-lenges is to optimize biomass productivity. It has been de-monstrated that optimal operating conditions can be achie-ved when the ethanol concentration in the bioreactor is regu-lated at the lowest possible value. To ...
Parameter estimation in a model of E. coli MG1655 culture
DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde l... more DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde la production scientifique de l'ULB.L'interface de recherche DI-fusion permet de consulter les publications des chercheurs de l'ULB et les thèses qui y ont été défendues.
Linearizing control is a popular approach to control bioprocesses, which has received considerabl... more Linearizing control is a popular approach to control bioprocesses, which has received considerable attention is the past several years. This control approach is however quite sensitive to modeling uncertainties, thus requiring some on-line parametric adaptation so as to ensure performance. In this study, this usual adaptive strategy is compared in terms of implementation and performance to a robust strategy, where the controller has a fixed parametrization which is determined using a LMI framework so as to ensure robust stability and performance. Fed-batch cultures of yeast and bacteria are considered as application examples.
Robust linearizing control of yeast and bacteria fed-batch cultures
DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde l... more DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde la production scientifique de l'ULB.L'interface de recherche DI-fusion permet de consulter les publications des chercheurs de l'ULB et les thèses qui y ont été défendues.
In this study, we consider the problem of optimizing the productivity of fed-batch cultures of S.... more In this study, we consider the problem of optimizing the productivity of fed-batch cultures of S. Cerevisiae. This bioprocess is described by nonlinear kinetic models based on the bottleneck assumption of Sonnleitner and Käppeli (1986) and ethanol inhibition resulting from the fermentation of a possible excess of substrate feeding. In contrast with most published studies where the critical substrate level is assumed constant, we investigate the situation where this critical substrate level depends on the yeast respiratory capacity, and in turn on the oxygen and ethanol concentration in the culture medium. The challenge is thus to maintain the process at a high level of productivity by avoiding the accumulation of ethanol. To this end, two adaptive extremum-seeking schemes coupled to a feedback control loop regulating either the substrate or ethanol concentration are developed.
In this paper, experimental investigations of a robust RST control scheme for the regulation of t... more In this paper, experimental investigations of a robust RST control scheme for the regulation of the ethanol in fed-batch cultures of S. cerevisiae is presented. Our main objective is to prove its efficiency and robustness in experimental applications ranging from laboratory to industrial scales. The controller only requires one on-line measurement signal, making it easily implementable in an industrial environment. Disturbance rejection is ensured thanks to an on-line parameter adaptation procedure, which delivers as a side product an estimate of the growth rate that can be used for process monitoring purposes. The robustification of the controller is achieved in a simple way, using the observer polynomial.
Productivity optimization of cultures of S. cerevisiae through a robust control strategy
DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde l... more DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde la production scientifique de l'ULB.L'interface de recherche DI-fusion permet de consulter les publications des chercheurs de l'ULB et les thèses qui y ont été défendues.
Modelling a hyper-proliferative E. coli
Experimental validation of an Extended Kalman Filter estimating acetate concentration in E. coli cultures
Journal of Process Control, 2013
Optimizing control of Escherichia coli cultures depends on the availability of appropriate on-lin... more Optimizing control of Escherichia coli cultures depends on the availability of appropriate on-line sensors for the main culture components. An efficient and practical way to maintain E. coli cultures in the neighborhood of the optimal operating conditions is to regulate the acetate concentration at a constant low level. Unfortunately, reliable acetate probes are currently not available on the market. A way to overcome this lack of information is to design software sensors. In this work, observability conditions are first examined, and Extended ...
Investigation of the Effect of a Genetic Manipulation through Macroscopic Dynamic Modeling
8th IFAC Symposium on Biological and Medical Systems (2012), 2012
DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde l... more DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde la production scientifique de l'ULB.L'interface de recherche DI-fusion permet de consulter les publications des chercheurs de l'ULB et les thèses qui y ont été défendues.
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Extrusion process by Laurent Dewasme
Fermentation process by Laurent Dewasme