REGIÃO METROPOLITANA DE GOIÂNIA (RMG)Campus Samambaia, Campus Colemar Natal e Silva, Campus Aparecida de Goiânia.http://repositorio.bc.ufg.br//handle/ri/5752024-07-15T16:56:52Z2024-07-15T16:56:52Z140501Uma proposta metodológica para mapear a dissecação do relevo e aplicá-la no Parque Nacional da Serra da Canastra-MGhttp://repositorio.bc.ufg.br//handle/ri/248802024-07-15T16:50:45Z2021-01-01T00:00:00Zdc.title: Uma proposta metodológica para mapear a dissecação do relevo e aplicá-la no Parque Nacional da Serra da Canastra-MG
dc.description.abstract: This work proposes a map of the relief dissection using the bivariate geovisualization technique. This map makes it possible to verify the influence of each variable; notching of the valley and interfluvial dimension, separately or combined. The Serra da Canastra National Park, southwest of Minas Gerais, was chosen to apply the method due to its geomorphologic characteristics and altimetry amplitude. The results presented by bivariate map, showed equivalence with the other proposals existing in the Brazilian literature, with good precision and spatial correlation, mainly where the dissection is “very strong”. The methodology has the advantage of universality, since its application does not depend on the database used, without the need for interference by decision makers, based on the digital elevation model (DEM) of any geographic region.
2021-01-01T00:00:00ZUma proposta metodológica para o mapeamento de superfícies de aplanamentohttp://repositorio.bc.ufg.br//handle/ri/248792024-07-15T16:44:55Z2022-06-01T00:00:00Zdc.title: Uma proposta metodológica para o mapeamento de superfícies de aplanamento
dc.description.abstract: A mapping methodology of planation surfaces based on automated altimetric stratification is proposed in this work. In this methodology, mathematical concepts related to the variation of the function of pixels frequency vs. altitude are usedto obtain the grouping of relief forms. The automatic clustering allows to distinguish the planation surfaces from elevationwithout the interference of decision maker. The input data for the execution of the mapping algorithm is the variation of elevation as a function of the number of pixels, extracted from SRTM data. The mapping of planation surfaces and the validation of computational algorithm were carried out for an area located in the municipality of Chapada Gaúcha, Minas Gerais State, Brazil, which presents two planation surfaces recognized in the literature. The landforms in the study area were associated with three planation cycles, interpreted as corresponding toKing’sPost-Gondwana, South American and Velhas surfaces. Remaining (reserved) and dissected landforms from South American and Velhas surfaces were mapped, while forPost-Gondwana surface only dissected landforms were identified. The mapped surfaces showed an important correlation with the regional soil types, indicating that the spatial distribution of surficial formations is directly related to the distribution of the planation surfaces. The results showed that the proposed algorithm can automatically reveal the relief organization ofa region, indicate characteristics of the planation surfaces such as the degree of flatness and leveling, in addition to helping to understand the relationship between landforms and soil distribution. The method is suitable for tectonically stablenot-tiltedreliefs and for areas of stepped planation surfaces.The method is suitable for stepped landsurfaces located at tectonically stable and not-tilted areas.
2022-06-01T00:00:00ZTeleportation of a weak coherent cavity field statehttp://repositorio.bc.ufg.br//handle/ri/248782024-07-15T12:44:03Z2016-01-01T00:00:00Zdc.title: Teleportation of a weak coherent cavity field state
dc.description.abstract: In this paper we propose a scheme to teleport a weak coherent cavity field state. The scheme relies on the resonant atom-field interaction inside a high-Q cavity. The mean photon-number of the cavity field is assumed much smaller than one, hence the field decay inside the cavity can be effectively suppressed.
2016-01-01T00:00:00ZModulation of localized solutions in an inhomogeneous saturable nonlinear Schrödinger equationhttp://repositorio.bc.ufg.br//handle/ri/248772024-07-15T12:41:27Z2017-01-01T00:00:00Zdc.title: Modulation of localized solutions in an inhomogeneous saturable nonlinear Schrödinger equation
dc.description.abstract: In this paper we study the modulation of localized solutions by an inhomogeneous saturable nonlinear medium. Throughout an appropriate ansatz we convert the inhomogeneous saturable nonlinear Schrödinger equation in a homogeneous one. Then, via a variational approach we construct localized solutions of the autonomous equation and we present some modulation patterns of this localized structures. We have checked the stability of such solutions through numerically simulations.
2017-01-01T00:00:00ZZero-dimensional limit of the two-dimensional Lugiato-Lefever equationhttp://repositorio.bc.ufg.br//handle/ri/248762024-07-15T12:39:16Z2017-01-01T00:00:00Zdc.title: Zero-dimensional limit of the two-dimensional Lugiato-Lefever equation
dc.description.abstract: We study effects of tight harmonic-oscillator confinement on the electromagnetic field in a laser cavity by solving the two-dimensional Lugiato-Lefever (2D LL) equation, taking into account self-focusing or defocusing nonlinearity, losses, pump, and the trapping potential. Tightly confined (quasi-zero-dimensional) optical modes (pixels), produced by this model, are analyzed by means of the variational approximation, which provides a qualitative picture of the ensuing phenomena. This is followed by systematic simulations of the time-dependent 2D LL equation, which reveal the shape, stability, and dynamical behavior of the resulting localized patterns. In this way, we produce stability diagrams for the expected pixels. Then, we consider the LL model with the vortical pump, showing that it can produce stable pixels with embedded vorticity (vortex solitons) in remarkably broad stability areas. Alongside confined vortices with the simple single-ring structure, in the latter case the LL model gives rise to stable multi-ring states, with a spiral phase field. In addition to the numerical results, a qualitatively correct description of the vortex solitons is provided by the Thomas-Fermi approximation.
2017-01-01T00:00:00ZQuasi-one-dimensional approximation for Bose–Einstein condensates transversely trapped by a funnel potentialhttp://repositorio.bc.ufg.br//handle/ri/248752024-07-15T12:32:24Z2019-01-01T00:00:00Zdc.title: Quasi-one-dimensional approximation for Bose–Einstein condensates transversely trapped by a funnel potential
dc.description.abstract: Starting from the standard three-dimensional (3D) Gross–Pitaevskii equation (GPE) and using a variational approximation, we derive an effective one-dimensional nonpolynomial Schrödinger equation (1D-NPSE) governing the axial dynamics of atomic Bose–Einstein condensates (BECs) under the action of a singular but physically relevant funnel-shaped transverse trap, i.e. an attractive 2D potential ∼−1/r (where r is the radial coordinate in the transverse plane), in combination with the repulsive self-interaction. Wave functions of the trapped BEC are regular, in spite of the potential's singularity. The model applies to a condensate of particles (small molecules) carrying a permanent electric dipole moment in the field of a uniformly charged axial thread, as well as to a quantum gas of magnetic atoms pulled by an axial electric current. By means of numerical simulations, we verify that the effective 1D-NPSE provides accurate static and dynamical results, in comparison to the full 3D GPE, for both repulsive and attractive signs of the intrinsic nonlinearity.
2019-01-01T00:00:00ZAnderson localization induced by interaction in linearly coupled binary Bose-Einstein condensateshttp://repositorio.bc.ufg.br//handle/ri/248742024-07-15T12:28:42Z2021-01-01T00:00:00Zdc.title: Anderson localization induced by interaction in linearly coupled binary Bose-Einstein condensates
dc.description.abstract: In this paper we investigate the existence of Anderson localization induced by one specific component of a binary Bose-Einstein condensate (BEC). We use a mean-field approach, in which each type of particle of the BEC is considered as a specific field, and we consider that only one kind of particle is subject to a quasiperiodic potential, which induces a localization in the partner field. We assume the system is under a Rabi coupling, i.e., a linear coupling mixing the two-field component, and we investigate the conditions associated with the parameter values of the system for observing the localization. Numerical simulations are performed, confirming the existence of Anderson localization in the partner field.
2021-01-01T00:00:00ZParametrically driven localized magnetic excitations with spatial inhomogeneityhttp://repositorio.bc.ufg.br//handle/ri/248732024-07-15T12:27:02Z2019-01-01T00:00:00Zdc.title: Parametrically driven localized magnetic excitations with spatial inhomogeneity
dc.description.abstract: In this paper we study an inhomogeneous ferromagnet with uniaxial anisotropy and applied magnetic field via the magnetic field component of the propagating electromagnetic wave in the medium. It is observed that the magnetic excitations are governed by localized solutions and the corresponding electromagnetic wave is modulated in the form of soliton modes driven by the inhomogeneity. The localized solutions are obtained in an analytical way by employing a variational approach. The effect of different types of magnetic inhomogeneity is studied for three different types of ansätze. Interestingly, the regions of validity of each ansatz are slightly different, demonstrating that both may be interesting for understanding the whole system.
2019-01-01T00:00:00ZLocalization of optical pulses in guided wave structures with only fourth order dispersionhttp://repositorio.bc.ufg.br//handle/ri/248722024-07-15T12:24:47Z2019-01-01T00:00:00Zdc.title: Localization of optical pulses in guided wave structures with only fourth order dispersion
dc.description.abstract: Inspired by the recent realization of pure-quartic solitons (Blanco-Redondo et al. (2016) [1]), in the present work we study the localization of optical pulses in a similar system, i.e., a silicon photonic crystal air-suspended structure with a hexagonal lattice. The propagation of ultrashort pulses in such a system is well described by a generalized nonlinear Schrödinger (NLS) equation, which in certain conditions works with near-zero group-velocity dispersion and third order dispersion. In this case, the NLS equation has only the fourth order dispersion term. In the present model, we introduce a quasiperiodic linear coefficient that is responsible to induce the localization. The existence of Anderson localization has been confirmed by numerical simulations even when the system presents a small defocusing nonlinearity.
2019-01-01T00:00:00ZAn effective equation for quasi-one-dimensional funnel-shaped Bose–Einstein condensates with embedded vorticityhttp://repositorio.bc.ufg.br//handle/ri/248712024-07-15T12:22:29Z2022-01-01T00:00:00Zdc.title: An effective equation for quasi-one-dimensional funnel-shaped Bose–Einstein condensates with embedded vorticity
dc.description.abstract: On the basis of a recently introduced model for the Bose–Einstein condensate (BEC) trapped
in the 2D “funnel” potential, ∼ −r−1, we develop analysis for vortex modes, which are confined in the
transverse direction by the self-attraction, or by the trapping potential, in the case of self-repulsion. Linear
3D wave functions are found exactly for eigenstates with an orbital momentum. In the case of self-repulsion,
3D wave functions are obtained by means of the Thomas–Fermi approximation. Then, with the help
of the variational method, the underlying Gross–Pitaevskii equation is reduced to a 1D nonpolynomial
Schr¨odinger equation (NPSE) for modes with zero or nonzero embedded vorticity, which are tightly confined
by the funnel potential in the transverse plane. Numerical results demonstrate high accuracy of the NPSE
reduction for both signs of the nonlinearity. The analysis is performed for stationary modes and for traveling
ones colliding with a potential barrier. By means of simulations of NPSE with the self-attraction, collisions
between solitons are studied too, demonstrating elastic and inelastic outcomes, depending on the impact
velocity and underlying vorticity. A boundary of the stability of 3D vortices with winding number S = 1
against spontaneous splitting in two fragments is identified in the case of the self-attraction, all vortices
with S ≥ 2 being unstable.
2022-01-01T00:00:00Z