Schwarz alternating domain decomposition approach for the solution of mixed heat convection flow problems based on the method of approximate particular solutions

The incompressible two-dimensional Navier-Stokes equations including thermal energy balance equation are solved by the recently developed Method of Approximate Particular Solutions (MAPS). In a previous authors’ work this method was implemented to solve the two-dimensional Stokes equations by employing the pressure and velocity particular solutions obtained by Oseen’s decomposition with the Multiquadric (MQ) RBF as non-homogeneous term. A pressure-velocity linkage strategy is not required since the pressure particular solutions are obtained from the velocity ones. In the present contribution, the Navier-Stokes equations with Boussinesq approximation are solved by linearizing the convective term in a Picard iterative scheme. With the velocity values obtained at each of the Picard iterations, the energy conservation equation is solved by the MAPS by approximating temperature with the particular solutions of a Poisson problem with the MQ as a forcing term. With the aim of improving the computational efficiency of the global strategy, the two-dimensional domain is split into overlapped rectangular subdomains where the Schwarz Alternating Algorithm is employed to find a solution by using velocity and temperatures values from neighbouring zones as boundary conditions. The mixed convection lid-driven cavity flow problem is solved for moderate Reynolds and low Richardson numbers with the aim of validating the proposed method

Ecological host fitting of Trypanosoma cruzi TcI in Bolivia: mosaic population structure, hybridization and a role for humans in Andean parasite dispersal.

An improved understanding of how a parasite species exploits its genetic repertoire to colonize novel hosts and environmental niches is crucial to establish the epidemiological risk associated with emergent pathogenic genotypes. Trypanosoma cruzi, a genetically heterogeneous, multi-host zoonosis, provides an ideal system to examine the sylvatic diversification of parasitic protozoa. In Bolivia, T. cruzi I, the oldest and most widespread genetic lineage, is pervasive across a range of ecological clines. High-resolution nuclear (26 loci) and mitochondrial (10 loci) genotyping of 199 contemporaneous sylvatic TcI clones was undertaken to provide insights into the biogeographical basis of T. cruzi evolution. Three distinct sylvatic parasite transmission cycles were identified: one highland population among terrestrial rodent and triatomine species, composed of genetically homogenous strains (Ar = 2.95; PA/L = 0.61; DAS = 0.151), and two highly diverse, parasite assemblages circulating among predominantly arboreal mammals and vectors in the lowlands (Ar = 3.40 and 3.93; PA/L = 1.12 and 0.60; DAS = 0.425 and 0.311, respectively). Very limited gene flow between neighbouring terrestrial highland and arboreal lowland areas (distance ~220 km; FST = 0.42 and 0.35) but strong connectivity between ecologically similar but geographically disparate terrestrial highland ecotopes (distance >465 km; FST = 0.016-0.084) strongly supports ecological host fitting as the predominant mechanism of parasite diversification. Dissimilar heterozygosity estimates (excess in highlands, deficit in lowlands) and mitochondrial introgression among lowland strains may indicate fundamental differences in mating strategies between populations. Finally, accelerated parasite dissemination between densely populated, highland areas, compared to uninhabited lowland foci, likely reflects passive, long-range anthroponotic dispersal. The impact of humans on the risk of epizootic Chagas disease transmission in Bolivia is discussed

On the adequacy of Adams-Bashforth sampled-data models for characterizing complex underwater-vehicle dynamics with noisy measurements

In this paper the adequacy of high order interpolation-based approaches to describe highly perturbed complex dynamics in discrete time was analyzed. The analysis establishes features of the approaches related to modularity, consistency with the model order and the sampling times, and accuracy in disturbed contexts with noisy measurements. A detailed study of the sensitivity of local prediction errors under a high signal-to-noise ratio is carried out with analytical expressions in dependence of physical coefficients of the vehicle. The different interpolation-based approaches were illustrated with simulations using from an AUV-like (Autonomous Underwater Vehicle) system with a few degrees of freedom (DoF), to a ROV (Remotely Operated Vehicle) model of 6 DoF with complex navigation paths.Sociedad Argentina de Informática e Investigación Operativa (SADIO

A sensor for vision-based navigation in underwater path tracking with color and edge segmentation

This paper aims the design and implementation of a visionbased sensor for navigation of underwater vehicles with adaptive attributes. The objective pointed out is a sensor for tracking of underwater lines. The sensor employs a basic structure with a pixel-wise AND operation of binarized frames of separated channels HSV and an edgesegmented frame. The basic sensor performs well by good illuminated scenes. By significant drops of luminance, the efficiency falls. So an adaptive sensor is proposed over the basic structure. It operates on the brightness channel carrying out a maximization of contains in the accumulator bins of a Hough transformation. It has proven to enhanced the identification of the tracked line increasing the success rate.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Two dimensional solution of the advection-diffusion equation using two collocation methods with local upwinding RBF

The two-dimensional advection-diffusion equation is solved using two local collocation methods with Multiquadric (MQ)Radial Basis Functions (RBFs). Although both methods use upwinding, the first one, similar to the method of Kansa, approximates the dependent variable with a linear combination of MQs. The nodes are grouped into two types of stencil: cross-shaped stencil to approximate the Laplacian of the variable and circular sector shape stencil to approximate the gradient components. The circular sector opens in opposite to the flow direction and therefore the maximum number of nodes and the shape parameter value are selected conveniently. The second method is based on the Hermitian interpolation where the approximation function is a linear combination of MQs and the resulting functions of applying partial differential equation (PDE) and boundary operators to MQs, all of them centred at different points. The performance of these methods is analysed by solving several test problems whose analytical solutions are known. Solutions are obtained for different Peclet numbers, Pe, and several values of the shape parameter. For high Peclet numbers the accuracy of the second method is affected by the ill-conditioning of the interpolation matrix while the first interpolation method requires the introduction of additional nodes in the cross stencil. For low Pe both methods yield accurate results. Moreover, the first method is employed to solve the twodimensional Navier-Stokes equations in velocity-vorticity formulation for the lid-driven cavity problem moderate Pe

A sensor for vision-based navigation in underwater path tracking with color and edge segmentation

This paper aims the design and implementation of a visionbased sensor for navigation of underwater vehicles with adaptive attributes. The objective pointed out is a sensor for tracking of underwater lines. The sensor employs a basic structure with a pixel-wise AND operation of binarized frames of separated channels HSV and an edgesegmented frame. The basic sensor performs well by good illuminated scenes. By significant drops of luminance, the efficiency falls. So an adaptive sensor is proposed over the basic structure. It operates on the brightness channel carrying out a maximization of contains in the accumulator bins of a Hough transformation. It has proven to enhanced the identification of the tracked line increasing the success rate.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Solución bidimensional sin malla de la ecuación no lineal de convección-difusión-reacción mediante el método de Interpolación Local Hermítica

A meshless numerical scheme is developed for solving a generic version of the non-linear convection-diffusion-reaction equation in two-dimensional domains. The Local Hermitian Interpolation (LHI) method is employed for the spatial discretization and several strategies are implemented for the solution of the resulting non-linear equation system, among them the Picard iteration, the Newton Raphson method and a truncated version of the Homotopy Analysis Method (HAM). The LHI method is a local collocation strategy in which Radial Basis Functions (RBFs) are employed to build the interpolation function. Unlike the original Kansa’s Method, the LHI is applied locally and the boundary and governing equation differential operators are used to obtain the interpolation function, giving a symmetric and non-singular collocation matrix. Analytical and Numerical Jacobian matrices are tested for the Newton-Raphson method and the derivatives of the governing equation with respect to the homotopy parameter are obtained analytically. The numerical scheme is verified by comparing the obtained results to the one-dimensional Burgers’ and two-dimensional Richards’ analytical solutions. The same results are obtained for all the non-linear solvers tested, but better convergence rates are attained with the Newton Raphson method in a double iteration scheme.Se desarrolla un esquema numérico sin malla para resolver una versión genérica de la ecuación no lineal de convección-difusión-reacción en dominios bidimensionales. El método de Interpolación Hermitiana Local (LHI) se emplea para la discretización espacial y se implementan varias estrategias para la solución del sistema de ecuaciones no lineal resultante, entre ellas la iteración Picard, el método Newton Raphson y una versión truncada del Método de Análisis de Homotopía. (JAMÓN). El método LHI es una estrategia de colocación local en la que se utilizan funciones de base radial (RBF) para construir la función de interpolación. A diferencia del método original de Kansa, el LHI se aplica localmente y los operadores diferenciales de ecuación límite y gobernante se utilizan para obtener la función de interpolación, dando una matriz de colocación simétrica y no singular. Las matrices analíticas y numéricas jacobianas se prueban para el método de Newton-Raphson y las derivadas de la ecuación de gobierno con respecto al parámetro de homotopía se obtienen analíticamente. El esquema numérico se verifica comparando los resultados obtenidos con las soluciones analíticas unidimensionales de Burgers y Richards bidimensionales. Se obtienen los mismos resultados para todos los solucionadores no lineales probados, pero se obtienen mejores tasas de convergencia con el método Newton Raphson en un esquema de doble iteración