Modélisation et observation des bioprocédés à membranes (application à la digestion anaérobie)

Cette thèse porte sur la modélisation des réacteurs membranaires anaérobies. Dans une première partie, nous proposons une analyse mathématique générique d'un modèle de digestion anaérobie en deux étapes appelé AM2. La principale limitation du développement des réacteurs membranaires étant le risque de colmatage, nous proposons, dans une seconde partie, d'étendre le modèle AM2 en incorporant une nouvelle variable d'état modélisant la dynamique des Produits Microbiens Solubles (SMP) dont le rôle dans le colmatage des membranes a été démontré. Une étude mathématique exhaustive de ce nouveau modèle appelé AM2b est réalisée pour comprendre et comparer les comportements qualitatifs des deux modèles. Dépendant des conditions de fonctionnement et des valeurs des paramètres biologiques utilisées, nous montrons que ce nouveau modèle peut se comporter comme le modèle initial AM2, ou, au contraire, présenter un comportement qualitatif très différent. L'étape suivante sera d'utiliser ce modèle pour la synthèse de régulateurs. Toutefois, le manque de capteurs en-ligne nous a amené, dans une troisième partie, à procéder à la synthèse d'un certain nombre d'observateurs d'état classiques. Au regard des caractéristiques spécifiques des bioprocédés, cette dernière partie se termine par la proposition de nouvelles pistes pour l'estimation d'état et de paramètres par des méthodes stochastiques, notamment les filtres particulaires dont nous présentons brièvement le principe.This thesis focuses on the modeling of anaerobic membrane reactors. In the first part, we propose a generic mathematical analysis of a two-step model of the anaerobic digestion called AM2. The main limitation in the development of membrane reactors being the risk of clogging, we propose in a second part, to extend the AM2 model by incorporating a new state variable modeling the dynamics of the so-called Soluble Microbial Products (SMP) whose role in the clogging of the membranes has been demonstrated. A complete mathematical study of this new model called AM2b is realized to understand and compare the behavior of both models. Depending on operating conditions and on the model parameters values, we show that this new model can behave as the initial model AM2, or, conversely, have a completely different qualitative behavior. The next step is to use this model for the synthesis of controllers. However, the lack of online sensors led us to a third part where we carry out the synthesis of several state observers. In view of the specific characteristics of bioprocesses, this last part ends by proposing new ways to estimate both state and parameters using stochastic methods, including particulate filters which the concepts are briefly reviewed.MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Anaerobic Membrane BioReactor modeling in the presence of Soluble Microbial Products (SMP) - the Anaerobic Model AM2b

International audienceThis paper deals with the modification of the AM2 model (Bernard and al. (2001)) to integrate the production and the degradation of the Soluble Microbial Products (SMP) in an Anaerobic Membrane BioReactor (AMBR). The developed model takes into account the characteristics of membrane bioreactors, namely i) there is no biomass in the effluent, ii) part of the SMP, corresponding to the biggest molecules, is retained in the reactional medium, iii) the decay rate and the withdraw of the biomass are considered. Possible equilibria of the system are calculated, and the influence of the maximum growth rate of the biomass on the SMP on these equilibria is analyzed. It is shown that the presence of this new variable in the model changes the qualitative properties of the classical AM2 model

Bifurcation and stability analysis of a two step model for monitoring anaerobic digestion processes

This paper deals with the equilibria and stability analysis of the two step anaerobic model initially proposed by [12] to describe the dynamical behavior of an anaerobic fixed-bed wastewater treatment process. In a first part, the model is analyzed: its equilibria and their stability are established considering qualitative properties of the kinetics. In a second part, it is shown that the overloading tolerance (denoted herein OT), a parameter proposed in [9] to monitor anaerobic processes on-line, may not be suitable for monitoring the system and even causes serious problems under certain functioning conditions. Based on the analysis results established in the first part, a modified OT is proposed and evaluated in simulation

Heat transfer enhancement through different heat sink/impinging air jet parameters an experimental approach

In the present work, improving the thermal performance of a central processing unit (CPU) cooling system consisting of a plate fin minichannel heat sink exposed to an air jet of impact is accomplished. The height of the impinging air jet duct, the mode of air flow on the heat sink, air blowing mode and as well as the suction blow mode "pull" and the air jet duct geometry are three important influence parameters on the phenomenon. The results obtained show that a jet height H = 20 mm, a convergent duct of H = 40 mm in height and a hair dryer tip provide further improvement of the cooling technique. The two preceding parameters combined with the fan air suction blow mode improve the performance by at least 11,2% compared to the initial configuration (marketed product), having as characteristics (H= = 0 mm, fan in the blowing push mode). The use of a converging duct and a hair dryer conduit show that the velocities from the hair dryer tip far exceed those from the best standard conduit height, H = = 20 mm. That said, the improvement of the flow in the central zone is substantially achieved, which consequently improves the heat removal in this zone at least 19%

A Luenberger like observer for the AM2 model

In this paper, we deal with the problem of designing a new class of observers for uncertain bioreactor models. The main idea is to construct a nonlinear observer with linear errors, which has an adjustable and robust convergence. Simulation results are pesented using a model of chemostat and a model of an anaerobic digestion process for the treatment of wastewater

Etude, analyse et réalisation d'un système de choix automatique de scènes dans le cadre d'une thérapie par mise en situation virtuelle pour la phobie sociale

Ce travail de thèse s inscrit dans le cadre de l étude des réponses optiques des nanocristaux à base de semiconducteurs II-VI. Ici nous avons déterminé les propriétés optiques de ZnTe, ZnS et ZnS : Mn nanostructurés par ellipsométrie spectroscopique (SE). Nous avons déterminé la fonction diélectrique et les transitions optiques des NC-ZnTe par SE dans la gamme spectrale 0.6 à 6.5 eV. L influence de la taille des NC sur les propriétés optiques et en particulier sur les transitions optiques a été aussi montrée. Les réponses optiques ont été déterminées en utilisant deux modèles : le modèle des points critiques d Adachi et la loi de dispersion de Tauc-Lorentz. Tout au long de ce travail, nous avons tenté de contribuer à la compréhension du processus d absorption dans les NC semi-conducteurs avec une technique non destructive capable de rendre compte des phénomènes liés à la réduction de la taille. Malgré le caractère indirect de l ellipsométrie nécessitant une bonne connaissance de l échantillon, nous avons démontré qu elle est capable de déterminer plusieurs propriétés des NC (indice de réfraction complexe, coefficient d absorption, énergie de gap, signatures des transitions optiques, excès de NC, taille moyenne, épaisseurs des couches de silice) et même de tenir compte des défauts liés à l implantationIn this work, we report on the study of the optical responses of nanocrystals semiconductor based II-VI. Here we have determined the optical properties of nanostructured ZnTe, ZnS and 'ZnS:Mn' by spectroscopic ellipsometry (SE). We have obtained the dielectric function and optical transitions of NC-ZnTe by spectroscopic ellipsometry in the spectral range 0.6 à 6.5 eV. The influence of the NC size on the optical properties and on the optical transitions was also shown. The optical responses were extracted using two models: the generalized critical points model of Adachi and the Tauc-Lorentz dispersion formula. Throughout this work we have tried to contribute to the understanding of absorption processes in semiconductor NC with a nondestructive technique by tacking into account the phenomena related to quantum confinement. Despite the indirect nature of ellipsometry requiring a good knowledge of the sample, we demonstrated that it is able to determine several properties of NC (complex refractive index, absorption coefficient, energy gap, optical transition energies, NC of excess, thick layers of silica) and even to take account into defects due to implantationMETZ-SCD (574632105) / SudocSudocFranceF

Recycler les eaux usées pour l'irrigation

Brève de Mathématiques de la Planète Terr

Towards a systematic approach to reduce complex bioprocess models - Application to the ADM1

International audienceA mathematical reduction method named Homotopy is applied to the Anaerobic Digestion Model No. 1 or ADM1, cf. (Batstone et al., 2002), a complex model of bioprocess describing the anaerobic digestion. Because we are interested in what happens on small timescales, the proposed method neglects the slow dynamics keeping only the fastest ones in using the technique of eigenvalue-state association. This transformation is described by the Homotopy matrix H. Simulations show that the reduced model behaves globally like the initial model at steady states. This approach is confronted with the reduction method using balancing of empirical gramians, an approach that ensures the same input-output behaviour of the reduced model with regard to the original one

Modélisation mathématique d'un bioréacteur membranaire anaérobie

aeres : C-ACTIInternational audienceCe travail concerne la modification du modèle AM2 (ou AMOCO [4]) à quatre dimensions pour intégrer une nouvelle variable modélisant les Produits Microbiens Solubles (SMP). Le nouveau modèle décrit la dynamique d'un traitement biologique anaérobie des eaux usées dans un BioRéacteur Membranaire (BRM). On propose une analyse de ses points d'équilibre et de leur stabilité en fonction des valeurs d'un paramètre du système (taux de croissance maximale sur les SMP). This paper deals with the modification of the AM2 model (or AMOCO [4]) with four dimensions to integrate a new variable modelling the Soluble Microbial Products (SMP) the new model describes the dynamical behavior of an anaerobic wastewater treatment in a Membrane BioReactor (MBR). Depending on the model parameters (maximal growth rate on the SMP), the equilibria points and their stability are analyse

Modeling of the Soluble Microbial Products (SMP) in Anaerobic Membrane BioReactors (AMBR) : Equilibria and stability of the AM2b model ?

aeres : C-ACTIInternational audienceThis paper deals with the modification of the AM2 model (Bernard and al. (2001)) to integrate the production and the degradation of the Soluble Microbial Products (SMP) in an Anaerobic Membrane BioReactor (AMBR). The developed model takes into account the characteristics of membrane bioreactors, namely i) there is no biomass in the effluent, ii) part of the SMP, corresponding to the biggest molecules, is retained in the reactional medium, iii) the decay rate and the withdraw of the biomass are considered. Possible equilibria of the system are calculated, and the influence of the maximum growth rate of the biomass on the SMP on these equilibria is analyzed. It is shown that the presence of this new variable in the model changes the qualitative properties of the classical AM2 model