http://repositorio.unne.edu.ar/handle/123456789/119 2026-04-08T14:57:28Z 2026-04-08T14:57:28Z Natalini, Bruno http://repositorio.unne.edu.ar/handle/123456789/56232 2024-10-29T14:21:00Z 2005-10-01T00:00:00Z

The boundary element dual reciprocity method : multidomain approach for solving 3D potential problems Natalini, Bruno The Dual Reciprocity Method (DRM) is a BEM technique to approach domain dominant problems without loosing the boundary-only nature of the BEM. For this kind of problems, domain integrals are sometimes introduced in the integral formulation. The DRM converts the domain integrals into boundary integrals by means of approximation functions. The DRM is general and the number of applications solved using the procedure has been increasing in the literature since early 90s. However the DRM faces a serious drawback when applied to large problems: the resulting system of equations is dense and frequently ill-conditioned. A way to overcome this inconvenient feature is by using domain subdivision in the limiting case when the resulting internal mesh looks like a finite element grid. This technique is known as the Dual Reciprocity Method - Multi Domain approach (DRM-MD). The DRM-MD produces sparse and well-conditioned system of equations. It has been successfully applied to a variety of linear and non-linear fluid dynamics problems in 2D domains and showed good performance. The extension of the procedure to 3D cases, and especially to large 3D problems, is not straightforward since factors such as continuity of the elements, DRM approximation function, scaling, number of internal DRM nodes, etc., which largely affect the performance of the code, need to be selected. In this thesis, several schemes were tested in order to have an insight on 3D DRMMD implementation. A set of codes using quadratic tetrahedrons to discretize the domain was produced and ten DRM approximation functions, five globally supported and five compactly supported Radial Basis Functions (RBF), were tested for both Poisson and steady-state advection-diffusion problems using dis-continuous elements. Compactly supported RBFs showed the highest accuracy, while the augmented thin plate splines (ATPS) showed the highest consistency in terms of accuracy and convergence for the two examples considered. A problem for implementation of the compactly supported RBFs is the lack of guidelines in choosing the size of the support, which showed to have large influence on the accuracy and convergence when these types of RBFs are used. The ATPS showed satisfactory accuracy and since its use does not involve any extra parameters, at the moment it is this function the choice of the author of this thesis for use in the DRMMD. Besides, the effect of scaling and internal DRM nodes were tested using both continuous and discontinuous elements. Results showed that scaling must be always considered to obtain an optimum performance of the code. Internal DRM nodes improve the accuracy of the codes though they are not as important as in the classical single-domain DRM. The thesis includes a few contributions on computational implementation of the DRM-MD, among them, a general assembly procedure and an alternative way to represent partial derivatives. Finally, the simulation of the transport of a pollutant disposed in an underground repository under different scenarios, which is a large case, and a feasibility study of flow in unsaturated media, which is a strongly nonlinear case, are presented and discussed. The results presented here show that the iii DRM-MD is as versatile and efficient when applied to problems defined in 3D domains as it is when solving 2D problems.

2005-10-01T00:00:00Z Beneyto, Pablo Alejandro http://repositorio.unne.edu.ar/handle/123456789/51671 2023-06-12T23:09:55Z 2016-01-01T00:00:00Z

Modelado numérico de medios porosos multifásicos. Aplicación a filtración y estabilidad de taludes mediante algoritmos genéticos Beneyto, Pablo Alejandro Los modelos matemáticos para resolver el fenómeno de consolidación en medios porosos representan un tema ampliamente estudiado en la mecánica computacional moderna. Desde los primeros trabajos de Biot, a las complejas formulaciones actuales, se consideraron una amplia gama de situaciones mecánicas, condiciones térmicas, fluidos transportados, condiciones de contorno tipo decarga. En este trabajo se pretende demostrar que es posible desarrollar un nuevo modelo matemático apto para suelos de la región permita describir el comportamiento mecánico ante cargas (de materiales porosos con presencia de gas, líquido y poluente en sus intersticios),recurriendo técnicas numéricas como el Método de los Elementos Finitos para la integración de ecuaciones obtenidas y el posterior desarrollo del código necesario para su resolución por medio computador y su aplicación a taludes y y filtración mediante técnicas de optimización. Se presenta la deducción de las ecuaciones de gobierno correspondientes a las distintas fases que componen el medio poroso en estudio(solida, líquida y gaseosa),con la presencia adicional de fase poluente no miscible en agua, las cuales considerada como una fase adicional. Se presentan dos innovaciones al modelo basado en la descomposición de estado de tensiones desarrollado previamente por el grupo de investigación del Departamento de Mecánica Aplicada de la Facultad de Ingeniera de la UNNE :la incorporación de una fase de contaminantes inmiscibles al sistema de tres fases descriptas por Di Rado et.al. y la introducción de una función simple ponderada que permite utilizarlas curvas características succión-saturación para los componentes individuales en lugar de utilizar una curva de la mezcla de fluidos, presentando finalmente una generalización para N fases fluidas inmiscibles. Este enfoque matemático mejorado, permitirá ser reducido a otros mas restrictivos pero mas fáciles de resolver, cómo el caso saturado, el no saturado sin acoplamiento de la succión, la consolidación sin presencia de contaminantes, la consolidación con presencia de contaminantes o poluentes, pero sin acoplamiento de succión,etc.,al limitar convenientemente algunos coeficientes al valor requerido.

2016-01-01T00:00:00Z Pilar, Jorge Víctor http://repositorio.unne.edu.ar/handle/123456789/49966 2022-08-25T17:11:38Z 2003-09-01T00:00:00Z

Desenvolvimento de um sistema de apoio à decisão para a otimização de traçados de obras de engenharia civil : o caso do sistema de defesa contra inundações da cidade de Resistencia, Argentina Pilar, Jorge Víctor O traçado de obras com características lineares num espaço geográfico tem, em princípio, um número muito grande de soluções. A seleção de traçados mais convenientes é hoje abordada pela Pesquisa Operacional por meio da Programação Dinâmica tradicional e das técnicas para resolver o problema conhecido como leastcost-path, (caminho de mínimo custo). Por sua vez, o planejamento de espaços geográficos é feito com o auxílio de técnicas de SIG (sistemas de informação geográfica). O estudo algorítmico dos caminhos de mínimo custo não é novidade e até os programas comerciais para SIG mais utilizados têm incorporado comandos que, com certas limitações, resolvem esse problema. Mas, seja qual for a abordagem, sempre é preciso conhecer a priori a funçãoobjetivo (FO), e isto não é tarefa fácil, pois devem ser conjugados objetivos de satisfação de necessidades sociais, políticas, ambientais e econômicas, o que gera um verdadeiro problema de otimização multiobjetivo e multicritério. Este trabalho teve como foco principal elaborar um modelo de decisão para ajudar na formulação da FO, adotando o paradigma multiobjetivo/multicritério, explorando inclusive o relaxamento difuso de pareceres dos decisores. Foram utilizadas apenas ferramentas computacionais (software e hardware) simples, de ampla difusão entre os engenheiros e de baixo custo, como a planilha de cálculo Excel e o programa Idrisi 32, procurando explorar suas aptidões e limitações, sem recorrer à elaboração e/ou utilização de códigos computacionais próprios, sobre os quais muitas pessoas sentem receios até não serem testados suficientemente. Foi obtido um sistema de apoio à decisão eficaz e de fácil utilização e sua possibilidade de aplicação foi testada na definição do traçado ótimo de parte da defesa norte da cidade de Resistencia (Argentina).; Works´ layout with lineal characteristics in a geographical space has a large number of solutions. The more convenient layout selection is actually approached for the Operational Research through the traditional Dynamic Programming and the techniques to solve the well-known problem as least-cost-path. At the same time, the planning of geographical spaces is carried out with the GIS (Geographical Information Systems) aid. The algorithmic study of the minimum cost paths is not new and even the most used GIS commercial programs have incorporated commands which, with certain limitations solve the problem. However, it is always necessary to previously know the Objective-Function (OF), and this is not easy task, because objectives of social, political, environmental and economic needs must be conjugated, which generates a real problem of multiobjective and multi-criterion optimization. This work had as main focus the OF formulation, adopting the multiobjetive/ multicriterion paradigm, exploring even the fuzzy relax of the decision views. Only simple computing tools (software and hardware) were used, which are widely known among engineers, and they are not expensive, like Excel worksheet and the Idrisi 32 program, exploring their aptitudes and limitations, without using the elaboration or/and the use of computation codes, about with many people have mistrust until they are not checked enough. An efficient support decision aid and of easy use was the result, and the verification of its applicability was verified in the definition of the optimum layout of the north defense of Resistencia city (Argentina).

2003-09-01T00:00:00Z Di Rado, Gustavo Rubén http://repositorio.unne.edu.ar/handle/123456789/27681 2023-09-11T12:38:00Z 2016-01-01T00:00:00Z

Desarrollo de una herramienta de simulación de conducción de automóviles todo terreno para análisis de carreteras y seguridad vial Di Rado, Gustavo Rubén The highway, the vehicle and the driver are the main agents of a traffic system, and traffic safety is determined by their interaction. The main objective of a traffic engineer is to achieve that this relationship be as good as possible, thus, accomplish reduction of road accidents. The elements used in a road design, are the first step to get this objective. The geometric design and traffic signals must promote a confortable and fluid driving, thus avoiding abrupt maneuvers not provided by the driver. It is evident that horizontal alignment in flat territories, must have enough elements to help the driver to be awake, i. e. replace long alignment (more than 2 km), by wide curves, with big radii (2000 to 10000 mts), to oblige the driver to gently modify the trajectory and keep his attention. On the other hand, in territories with hills and mountains, it must be accomplished the maximum alignment length (2 km), and minimum alignment length (4 x V (km/h) expressed in meters) between curves, to mainly avoid a wide oscillation of velocities in the trajectory. In this sense, geometric consistency analysis allows identifying the use pattern of roads through operational speed estimate models and classification criteria. This may be performed in projects or in built roads. The velocities measurement procedure must be done in situ, with expensive specific equipment, great execution work, and actual danger. The use of a driving simulator appears as an essential complementary tool, that allows, at low cost, and in lab safety conditions, go around road segments generated in 3D environment. This process performed by different persons with different vehicles, allows a precise evaluation of the modeling segments. In this thesis, a driving simulator for road safety studies was developed and tested. Velocity and acceleration profiles, travel times, driver behaviors, trajectories and other parameters related to vehicle displacement were obtained.; La vía, el vehículo y el conductor, son los principales componentes de la estructura vial, y la seguridad vial depende de la interacción entre ellos. El objetivo del ingeniero de tránsito, es conseguir que esta relación sea lo más armoniosa posible, logrando así, disminuir considerablemente los siniestros viales. Los elementos utilizados en el proyecto de una carretera, representan el primer paso para lograr este objetivo. El diseño geométrico y la señalización vial, deben colaborar con una conducción confortable y fluida, evitando maniobras bruscas o que el conductor no pueda prever con suficiente anticipación. Es evidente, que la traza horizontal en territorios mayormente llanos, debe contener elementos que favorezcan que el conductor se mantenga alerta, esto es por ejemplo, reemplazar grandes alineamientos (superiores a 2 km), por curvas amplias de grandes radios (2000 a 10000 m) que obliguen al conductor a modificar suavemente su dirección y mantengan despierta su atención. Por otro lado, en territorios ondulados y montañosos, deben respetarse los valores de tangentes máxima (2 km) y mínima (4 x V (kph) expresada en metros) entre curvas, para evitar principalmente una muy amplia variación de velocidades en el trayecto. En este sentido el análisis de la consistencia geométrica es una herramienta que permite identificar el patrón de uso de las carreteras, a través de modelos de estimativa de velocidad operacional y criterios de clasificación. Esto puede realizarse para carreteras en proyecto o ya construidas. El procedimiento de medición de velocidades, debe ser concretado in situ, con equipamiento específico costoso, gran trabajo de elaboración y peligrosidad fáctica. El uso de un simulador de conducción de vehículos, aparece como una herramienta complementaria esencial, que permite, a bajo costo y en condiciones seguras de laboratorio, recorrer virtualmente tramos de carreteras generados en entornos 3D. Este proceso realizado por diferentes personas con diferentes características, y utilizando vehículos con diferentes capacidades, permite evaluar los tramos modelados con gran precisión. En la presente tesis se plantea el desarrollo y validación de una herramienta de simulación de conducción de automóviles para estudios de seguridad vial en carreteras. Se lograron obtener perfiles de velocidades, aceleraciones, tiempos de recorrido, comportamientos conductivos, trayectorias, y todos los parámetros relacionados con el desplazamiento del vehículo.

2016-01-01T00:00:00Z