945 resultados para second order metrics
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We show that by using second-order differential operators as a realization of the so(2,1) Lie algebra, we can extend the class of quasi-exactly-solvable potentials with dynamical symmetries. As an example, we dynamically generate a potential of tenth power, which has been treated in the literature using other approaches, and discuss its relation with other potentials of lowest orders. The question of solvability is also studied. © 1991 The American Physical Society.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The main goal of this bachelor work is the study of the physical properties of solids by thermal expansion coefficient measurements, which allows the exploration of various aspects of phase transitions. In this study, some theoretical aspects were focused, for example the first and second order phase transitions, Landau theory for phase transition and the volumetric thermal expansion coefficient. Furthermore, on the origin of the thermal expansion from the Lennard-Jones potential, that contains the anharmonic terms, which give rise to the phononic thermal expansion in solids
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The temperature dependencies of specific heat and spin susceptibility of a coupled dx2-y2 + idxy superconductor in the presence of a weak dxy component are investigated in the tight-binding model (1) on square lattice and (2) on a lattice with orthorhombic distortion. As the temperature is lowered past the critical temperature Tc, first a less ordered dx2-y2 superconductor is created, which changes to a more ordered dx2-y2 + idxy superconductor at Tcl(< Tc). This manifests in two second order phase transitions identified by two jumps in specific heat at Tc and Tc1. The temperature dependencies of the superconducting observables exhibit a change from power-law to exponential behavior as temperature is lowered below Tc1 and confirm the new phase transition. © 1998 Published by Elsevier Science B.V. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Engenharia Civil e Ambiental - FEB
Influence of morphological variables in photoelastic models with implants submitted to axial loading
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Purpose: This study used 12 photoelastics models with different height and thickness to evaluate if the axial loading of 100N on implants changes the morphology of the photoelastic reflection. Methods: For the photoelastic analysis, the models were placed in a reflection polariscope for observation of the isochromatic fringes patterns. The formation of these fringes resulted from an axial load of 100N applied to the midpoint of the healing abutment attached to the implant with 10.0mm x 3.75mm (Conexão, Sistemas de Próteses, Brazil). The tension in each photoelastic model was monitored, photographed and observed using the software Phothoshop 7.0. For qualitative analysis, the area under the implant apex was measured including the green band of the second order fringe of each model using the software Image Tool. After comparison of the areas, the performance generated by each specimen was defined regarding the axial loading. Results: There were alterations in area with different height and thickness of the photoelastic models. It was observed that the group III (30mm in height) presented the smallest area. Conclusion: There was variation in the size of the areas analyzed for different height and thickness of the models and the morphology of the replica may directly influence the result in researches with photoelastic models.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Química - IQ
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Pós-graduação em Ciência dos Materiais - FEIS
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Pós-graduação em Engenharia Mecânica - FEIS
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Física - IFT