A Complete Mathematical Model For Trichoderma Fungi Kinetics

We develop an unstructured mathematical model describing the growth kinetics of the Trichoderma fungus and the production of enzymes (cellulase) by degradation of a substrate (cellulose) in the rhizosphere. We integrate into this model the hydrolysis step of the organic matter and analyze the asymptotic behaviour of the obtained system. We show that our system evolves towards a global attractor consisting of infinite non-hyperbolic equilibria

R-adaptation par l'estimateur d'erreur hiérarchique

International audienceThe aim of this work is to devise a method to determine the optimal position of the nodes in a finite element discretization for a boundary value problem. The node displacement procedure (also called R-adaptation) is a crucial step in a global mesh adaptation procedure. In the present approch, we determine the nodal position by minimizing the approximation error. This error is evaluated using a hierarchical estimator. A numerical test is presented.L'objectif de ce travail est de déterminer la meilleure position des noeuds d'un maillage, utilisé lors de la discrétisation d'un problème aux limites par la méthode des éléments finis. La procédure de déplacement des noeuds (appelé aussi R-adaptation) est une étape importante dans la stratégie globale d'adaptation de maillage. La position optimale des noeuds est déterminée en minimisant l'erreur d'approximation. Pour évaluer cette erreur nous utilisons l'estimateur d'erreur hiérarchique. Un test numérique est présenté

Mortar finite element discretization of a model coupling Darcy and Stokes equations

As a first draft of a model for a river flowing on a homogeneous porous ground, we consider a system where the Darcy and Stokes equations are coupled via appropriate matching conditions on the interface. We propose a discretization of this problem which combines the mortar method with standard finite elements, in order to handle separately the flow inside and outside the porous medium. We prove a priori and a posteriori error estimates for the resulting discrete problem. Some numerical experiments confirm the interest of the discretization.EU Marie CurieMinisterio de Educación y Cienci

Analysis of an anaerobic digestion model in landfill with mortality term

International audienceWe study a mathematical model of anaerobic digestion with biomass recirculation, dedicated to landfill problems, and analyze its asymptotic behavior. We show that the global attractor is composed of an infinity of non-hyperbolic equilibria. For non-monotonic growth functions, this set is non connected, which impacts the performances of the bioprocess

Redes neurais para predição de series temporais

Diversas classes de modelos têm sido propostas como solução do dilema do passeio aleatório para previsão de séries temporais financeiras. Embora não haja nenhuma prova formal sobre sua previsibilidade, alguns trabalhos argumentam que, na prática, este fenômeno temporal é, de alguma forma, previsível. Portanto, este trabalho analisa qual a eficiência dos modelos (ARIMA, MultiLayer Perceptrons e Long Short-Term Memory para séries temporais propostos para a predição do índice Bovespa? como solução do dilema do passeio aleatório no problema de previsão de séries temporais financeiras. Uma análise experimental é conduzida com os modelos investigados utilizando uma série temporal relacionada ao Índice da Bolsa de Valores de São Paulo (IBOVESPA) utilizando normalização e diferenciação dos dados, janelamento temporal e otimização dos hiperparâmetros dos modelos. Os resultados alcançados demonstraram efetividade, em desempenho preditivo, dos modelos investigados

Analysis of an anaerobic digestion model in landfill with mortality term

We study a mathematical model of anaerobic digestion with biomass recirculation, dedicated to landfill problems, and analyze its asymptotic behavior. We show that the global attractor is composed of an infinity of non-hyperbolic equilibria. For non-monotonic growth function, this feature has impacts on the performances of the bioprocess

Green chemistry for treatment of liquid discharges from a dyeing industry: bio coagulation and flocculation

Textile industry is among the highly polluting industries in water effluent. It consumes large quantities of water and chemicals compounds. These releases can have varying characteristics regarding their volumes and pollutants concentrations. Therefore, adverse effects can be observed as consequence on environment and biodiversity. According to the environmental protection regulations in Morocco, the treatment of this water before discharge is compulsorily to avoid pollution of surface and ground water. The aim of our study is the treatment of these effluents by a physicochemical process using coagulation / flocculation.  Two coagulants of different type and purity are used. The first one “aluminum sulfate” is a pure coagulants used on industrial scale. The second “alum stone” is excerpt from the nature of Moroccan desert. Beside, two flocculants are compared, a natural extract from cactus and a polymer synthesized (polyacrylamide). The comparative study between a pure coagulant and a biocoagulant, with the two flocculants, showed a very good absorbency rate of reduction (ABS), turbidity (T), chemical oxygen demand (DCO), dry matter (DM) and chemical elements (sodium, lithium, nitrogen, phosphorus, boron, and silicon). By the jar test treatment process, the optimal dose of coagulants and flocculants to use in the neutral pH treatment was identified. The optimal dose used gives 85% of abatement efficiency absorbance, 90 % for turbidity and 80% for the chemical oxygen demand. Moreover, the dry matter content is over 25% and over 90% for some chemical elements