Orientador: Carlos Alberto Dutra Fraga Filho / Banca: Messias Meneguette Júnior / Banca: Vanessa Avansini Botta Pirani / Banca: Andriana Susana Lopes de Oliveira Campanharo / Resumo: Neste trabalho, apresenta-se o método Lagrangiano de partículas livre de malhas, Smoothed Particle Hydrodynamics (SPH). Neste método, o domínio do problema é discretizado empregando partículas que possuem propriedades físicas calculadas a partir das propriedades das partículas vizinhas, por meio de uma interpolação, utilizando uma função de suavização. O método foi aplicado para discretizar e adaptar para SPH um modelo de ruptura de barragem sobre um leito úmido conhecido como Dam-Break in Wet-Bed. Tal modelo, considerado ideal, é empregado nos testes de desempenho, precisão e confiabilidade de modelos matemáticos para validação de métodos numéricos aplicados a problemas de vertedouros em barragens hidrelétricas e ondas em praias. / Abstract: In this work, we present the Lagrangian mesh-free method of particles, Smoothed Particle Hydrodynamics (SPH). In this method, the problem domain is discretized using particles having physical properties calculated from neighboring particles by means of interpolation using a smoothing function. The method was applied to discretize and to adapt the SPH for a model of dam rupture on a wet-bed known as Wet-Dam-Break. This model, considered as ideal, is used in tests of performance, accuracy and reliability of mathematical models for validation of numerical methods applied to spillways problems in hydroelectric dams and waves at beaches. / Mestre

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The thesis presents models for short term planning (24 hours) of a hyro dominated hydrothermal power system. The purpose of the models is to minimizae the system operation costs to provide a forecasted load and keep enough spinning reserve. / This thesis presents models for short term planning (24 hours) of a hydro dominated hydrothermal power system. The purpose of the models is to minimize the system operation cost to provide a forecasted load and keep enough spinning reserve.   The thesis focuses on two issues in hydro power modelling. The first issue is the relationship between water discharged and power generated. This relationship is a non-linear and non-convex function. If the plant has several units, the efficiency of the plant will have local maximums, so called local best-efficiency points. The second issue is to take into account the cost of start-ups of hydro units in the planning.   The hydro model is mixed-integer. Discharg􀁐s are allowed at zero flow, the local best-efficiency points and on the continuous part between the local best-efficiency point with the highest flow and the point with maximum flow. This last continuous part is modelled as a linear function. In order to get data for the start-up cost a survey among the largest power producers in Sweden has been made, where three questions about start-ups of hydro power units has been asked: What causes the costs in the start-up?, How much does a start-up cost? and How do start-ups effect the short-term scheduling strategies of power producers in Sweden? The results show that a fair estimate of the start-up cost is about $3/MW nominal output. For the thermal plants a standard model with polynomial operation cost, start-up costs and ramp-rate constraints has been used. The model also includes the possibilities of purchasing and selling power to forecasted prices.   The planning problem is formulated as a mathematical programming problem. The solution technique uses Lagrange relaxation to decompose the problem into subproblems. There will be one subproblem for each hydro and thermal plant. In order to find good feasible solutions a heuristic technique to change the integer variables in the hydro system has been developed. The Lagrange multipliers are updated with the subgradient method.   The models are tested in three different load situations; a winter day (heavy load), an autumn day (medium load) and a summer day (light load). The result shows that the method gives near optimal schedules in reasonable computation time in cases with a normal part of the thermal units committed. The assumed start-up cost results in that hydro units almost never are started or stopped for one hour only. / <p>QC 20161206</p>

Made available in DSpace on 2018-08-01T23:29:12Z (GMT). No. of bitstreams: 1 tese_11906_71 - Suellen Freire Rigatto da Cruz.pdf: 3217831 bytes, checksum: e325a62e435db78eab3a87001876c20f (MD5) Previous issue date: 2018-03-08 / O petróleo continuará sendo a maior fonte de combustível nos próximos anos. No entanto, a extração de petróleo resulta em problemas como a formação de incrustação nas diversas etapas do processo de produção. O problema da incrustação, que ocorre a partir do processo de deposição, consiste quando as partículas depositadas reduzem, total ou parcialmente, o espaço aberto ao fluxo, resultando em um aumento de perda de carga e em uma redução na produção petrolífera. As deposições de partículas representam um problema significativo na indústria de petróleo e gás, sendo de grande relevância pesquisas nessa área. No presente trabalho, a deposição de partículas, em um escoamento turbulento e bifásico, no interior de uma tubulação horizontal foi modelada, com o software Ansys Fluent®, a partir da abordagem Euler-Lagrange com o Modelo de Fase Discreta Densa (DDPM) e da abordagem Euler-Granular. Devido ao elevado custo computacional decorrente do grande número de partículas injetadas, os resultados apontam que a abordagem Euler-Lagrange com o modelo DDPM não é adequada para resolver problemas envolvendo escoamentos com elevadas frações volumétricas de partículas, sendo mais adequada a abordagem Euler-Granular. O estudo também mostra a influência de determinados parâmetros no processo de deposição de partículas. Os aumentos nas taxas de deposição de partículas são diretamente proporcionais aos aumentos de rugosidade da parede da tubulação e de diâmetro das partículas. Os resultados também mostram valores de tempo computacional, velocidade e fração volumétrica de partículas que permitem uma melhor visualização do fenômeno de deposição para um tempo computacional requerido viável para o sistema computacional utilizado.

Orientador: Adriano Antonio Natale / Doutor

We consider systems of Euler-Lagrange equations with two degrees of freedom and with Lagrangian being quadratic in velocities. For this class of equations the generic case of the equivalence problem is solved with respect to point transformations. Using Lie's infinitesimal method we construct a basis of differential invariants and invariant differentiation operators for such systems. We describe certain types of Lagrangian systems in terms of their invariants. The results are illustrated by several examples.

The purpose of this thesis is to investigate radio systems for the protection of vehicles and grade crossings. The protection function used with wireless communication, associated with grade crossings (the vehicles), uses the radio propagation to dispatch message (data) from the radio facilities to the vehicles when the emergency button is pushed to enable the operator to assess the emergency situation in advance. The rule for static and non-static measurements of the radio system, concerned with the crossing, is able to offer an improved spectrum assignment tool. All measurement data was derived from measurements performed for the trains of The Taiwan Railway Administration. The results are compared with the European Norm and China National Standard. Thus, the electromagnetic interferences due to trains can be analyzed. In order to estimate the radio propagation distances, we particularize the several modes of radio propagation in detail, and use the Lagrange method to analyze and determine the distance.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1931. / The entire thesis text is included in file. Typescript and handwritten by author. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed December 3, 2009) Includes bibliographical references (p. 25) and index (p. 26).

Thèse de doctorat : Mécanique des Fluides : Strasbourg 1 : 2007. / Thèse soutenue sur un ensemble de travaux. Titre provenant de l'écran-titre. Bibliogr. 11 p.

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 1990. / Thesis Advisor(s): Salinas, David. "September 1990." Description based on title screen as viewed on December 17, 2009. DTIC Identifier(s): Vibration, sliding friction, guns barrels, cantilever beams, Euler equations, finite element analysis, transformations (mathematics), theses, frictionless holes, holes (openings), recoil. Author(s) subject terms: Cantilever beam, finite element method, axial motion, vibration, transient behavior. Includes bibliographical references (p. 110). Also available in print.