510 resultados para Perturbações harmónicas


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Consider a finite body of mass m (C1) with moments of inertia A, B and C. This body orbits another one of mass much larger M (C2), which at first will be taken as a point, even if it is not completely spherical. The body C1, when orbit C2, performs a translational motion near a Keplerian. It will not be a Keplerian due to external disturbances. We will use two axes systems: fixed in the center of mass of C1 and other inertial. The C1 attitude, that is, the dynamic rotation of this body is know if we know how to situate mobile system according to inertial axes system. The strong influence exerted by C2 on C1, which is a flattened body, generates torques on C1, what affects its dynamics of rotation. We will obtain the mathematical formulation of this problem assuming C1 as a planet and C2 as the sun. Also applies to case of satellite and planet. In the case of Mercury-Sun system, the disturbing potential that governs rotation dynamics, for theoretical studies, necessarily have to be developed by powers of the eccentricity. As is known, such expansions are delicate because of the convergence issue. Thus, we intend to make a development until the third order (superior orders are not always achievable because of the volume of terms generated in cases of first-order resonances). By defining a modern set of canonical variables (Andoyer), we will assemble a disturbed Hamiltonian problem. The Andoyer's Variables allow to define averages, which enable us to discard short-term effects. Our results for the resonant angle variation of Mercury are in full agreement with those obtained by D'Hoedt & Lemaître (2004) and Rambaux & Bois (2004)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Irrigação e Drenagem) - FCA

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Pós-graduação em Física - FEG

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Population aging and environmental protection have gained special importance after the economic, demographic and social recent changes. The objective of this paper was to promote theoretical and reflective review with emphasis on convergence between sustainable development and educational activities promoted by the University of the Third Age. We conducted a literature review to give full articles from the descriptors: aged, sustainable development indicators and environmental protection, published in English, Spanish and Portuguese, between January 1994 and June 2014, in national and international journals on the basis LiIlacs, Bireme and Medline. We used systematic data collection for sample analysis. The results indicate that the University of the Third Age develops teaching, research and extension, through actions based on aging and educational assumptions. In this context, environmental education is presented as a pedagogical process capable of awakening the critical capacity of the elderly, making it active social worker and leading him to a cultural design which ensures establishment of sustainable harmonious relationship with nature. It was concluded that the University of the Third Age contributes to initiatives that emphasize the relationships between systems and economic processes or social and natural processes, generating the construction of social values, knowledge, skills, attitudes and skills aimed at the conservation of the environment.

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Neste trabalho, foi estudado o modelo matemático oscilatório proposto por Daugulis et al. (1997) referente a um processo contínuo de fermentação alcoólica, de modo a compreender sua estrutura, variáveis, fenômenos e hipóteses postuladas. O estudo foi realizado de modo a compreender como os mecanismos de inibição por produto e substrato, e como os mecanismos adaptativos do microrganismo são levados em consideração pelo modelo, resultando no comportamento oscilatório desejado. Por fim, foram realizadas simulações com perturbações do tipo degrau na taxa de diluição e na concentração de substrato na alimentação, de modo a extrapolar o comportamento do modelo.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Engenharia Mecânica - FEIS

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This paper presents the development and the main results for an interleaved boost rectifier operating as a special input power stage for a trolleybus type vehicle, allowing its feeding by alternate current (AC) or direct current (DC) distribution power systems. When feeding with two wires (single phase) alternate current distribution system, the converter accomplish active power factor correction, providing a relatively sinusoidal current with low total harmonic distortion (THD) and fully complying with IEC 61000-3-4 standards. In addition, a management control system promotes the required automatic operation changes for the proposed rectifier when the vehicle is changing from the DC distribution power system to the AC distribution power system and vice-versa, keeping its original electrical DC system characteristics for the adjustable speed driver sub-system. The main experimental results for a prototype rated at 150kW are presented, considering its application for a trolleybus with DC adjustable speed driver, demonstrating the proposed converter benefits and the possibility of AC feeding system for trolleybus type vehicle.

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The dynamics of the rotation of a satellite is an old and classical problem, specially in the Euler formalism. However, with these variables, even in torque free motion problem, the integrability of the system is far from trivial, mainly when the three moments of the inertia are not equal. Another disadvantage occurs when the inclinations between some plans are null or close to zero, so the nodes become undetermined. In this work, we propose the use of modern Andoyer's variables. These are a set of canonical variables and therefore some significant advantages can be obtained when dealing with perturbation methods. On other the hand, the integrability of the torque free motion becomes very clear, as the system is reduced to a problem of one degree of freedom. The elimination of the singularities mentioned above, can be solved very easily, with Pincaré-type variables. In this work we give the background concepts of the Andoyer's variables and the disturbing potential is obtained for the rotational dynamics of a satellite perturbed by a planet. In the case when A = B (moments of inertia) and due to the current variables, the averaged system is trivially obtained through very simple integrations

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Física - IFT