Agglomerates are formed in industrial practice, e.g. pharmaceutical manufacturing and food processing. In case of fluidized bed productions, a solid-containing liquid, called binder, is sprayed on the particles and fl...
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Due to their advantageous properties, polyhydroxyalkanoates are a promising alternative to conventional petroleum-based plastics. Currently, high production costs in upstream and downstream have to be reduced to make ...
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Due to their advantageous properties, polyhydroxyalkanoates are a promising alternative to conventional petroleum-based plastics. Currently, high production costs in upstream and downstream have to be reduced to make the plastic material competitive. As most of the PHA producing organisms metabolize a wide range of substrates upstream cost can be reduced using carbon rich waste material. For large scale application sophisticated control approaches based on mathematical models can help to further increase the productivity. In the present work, a hybrid cybernetic model approach is presented, which is adapted to experiments with fructose and acetate feeding, respectively. Furthermore, the validated model was used to qualitatively predict the effect of co-substrate feeding.
Continuous particle agglomeration processes are important size-enlargement unit operations applied in the food, pharmaceutical and agricultural industry. For the improvement of these processes predictive mathematical ...
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Continuous particle agglomeration processes are important size-enlargement unit operations applied in the food, pharmaceutical and agricultural industry. For the improvement of these processes predictive mathematical models are of utmost importance. A widely applied modeling framework is the population balance equation, where the agglomeration kinetics are described by the so-called agglomeration kernel. The identification of functions describing these kinetics has turned out to be a challenging task. Therefore, this article deals with identifying such a kernel function by minimizing the L2-residual between experimentally obtained particle size distributions and simulations. The application of a stochastic gradient descent algorithm with automatic differentiation for minimization allows for the direct identification of the high-dimensional matrix representing the discretized kernel function. The comparison between the simulated and measured size distribution shows that the identified kernel is able to accurately describe the evolution of the particle size distribution. The algorithm presented in this contribution can be applied to a variety of similar processes and the identified kernels can be used in process optimization and automation applications.
Biotechnological processes still represent a challenge for process optimization and automation as the data landscape consists of unavailable, inaccurate, delayed or missing measurement information. As a first step tow...
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Wasserstoff (H 2 ) aus erneuerbaren Energien wird einen wachsenden Einfluss auf die globale Energiedynamik hin zu nachhaltigen und kohlenstoffneutralen Standards haben. Der Anteil von grünem H 2 ist noch zu gerin...
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Wasserstoff (H 2 ) aus erneuerbaren Energien wird einen wachsenden Einfluss auf die globale Energiedynamik hin zu nachhaltigen und kohlenstoffneutralen Standards haben. Der Anteil von grünem H 2 ist noch zu gering, um das Netto-Null-Ziel zu erreichen, während die Nachfrage nach hochwertigem Wasserstoff weiter steigt. Diese Faktoren verstärken den Bedarf an wirtschaftlich tragfähigen H 2 -Erzeugungstechnologien. Der vorliegende Artikel zielt darauf ab, die bestehenden Technologien zur Erzeugung von hochwertigem H 2 auf der Grundlage von Solarenergie zu bewerten. Technologien wie die Wasserelektrolyse, die photoelektrochemische und die solare thermochemische Wasserspaltung, Flüssigmetallreaktoren und die Plasmakonversion nutzen die Sonnenenergie direkt oder indirekt (als kohlenstoffneutrale Elektronen) und werden im Hinblick auf ihren derzeitigen Entwicklungsstand, ihre technischen Grenzen und ihr Zukunftspotenzial untersucht.
Abstract In this contribution we present a multiscale modeling approach to systematically explore the heterogeneity of biopolymer production in multicellular systems. The first step is a dynamic single cell model whic...
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Abstract In this contribution we present a multiscale modeling approach to systematically explore the heterogeneity of biopolymer production in multicellular systems. The first step is a dynamic single cell model which is based on the hybrid cybernetic modeling approach to include cell internal regulation. The single cell model is used for nonlinear analysis and the occurrence of multiple steady states is discussed. The single cell model is then reduced by using the lumped hybrid cybernetic approach and by approximation of enzyme levels. The reduced single cell model is used to develop a population balance model for predicting heterogeneity in multicellular production processes. Thus, we have combined the cybernetic modeling approach with population balance modeling, which consequently includes cell internal regulation. The multiscale modeling approach is first developed for the microorganism Ralstonia eutropha , which serves as a model and benchmark organisms. Good agreement between model predictions and experimental data is shown. An extension to Rhodospirillum rubrum is discussed, which shows interesting transient bimodal dynamics.
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