Circular Orbits
Mostrando 1-12 de 16 artigos, teses e dissertações.
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1. Trajectory Control During an Aeroassisted Maneuver Between Coplanar Circular Orbits
ABSTRACT: This paper presents the simulation results of an aeroassisted maneuver around the Earth, between coplanar circular orbits, from a geostationary orbit to a low orbit. The simulator developed considers a reference trajectory and a trajectory perturbed by external disturbances combined with non-idealities of sensors and actuators. It is able to operat
J. Aerosp. Technol. Manag.. Publicado em: 2014-06
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2. A Review of Gradient Algorithms for Numerical Computation of Optimal Trajectories
Abstract: In this paper, two classic direct methods for numerical computation of optimal trajectories were revisited: the steepest descent method and the direct one based upon the second variation theory. The steepest descent method was developed for a Mayer problem of optimal control, with free final state and fixed terminal times. Terminal constraints on t
J. Aerosp. Technol. Manag.. Publicado em: 2012-06
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3. The algorithmic weak stability boundary in earth-to-moon mission design: dynamical aspects and applicability.
This thesis consists of an extensive study of the Weak Stability Boundary (WSB) concept in low-energy Earth-to-Moon mission design within the mathematical structure provided by the Planar Circular Restricted Three-Body Problem (PCR3BP). By employing the patched three-body approach to approximate the Sun-Earth-Moon-spacecraft system, we examine and characteri
Publicado em: 2011
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4. Soluções Exatas de equações de Einstein para buracos negros e aneis de materia / Exact solutions of Einstein s equations for black holes and matter rings
Nesta tese, estudamos o problema de um anel delgado de matéria de densidade constante com um buraco negro de Kerr em seu centro. Nosso objetivo foi resolver as equações de Einstein no vácuo com simetria axial para esse sistema gravitacional. Para fazer a sobreposição não-linear do anel com o buraco negro (BN), utilizamos o método de Belinsky e Zakhar
Publicado em: 2009
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5. Orbitas periodicas em sistemas mecanicos / Periodic orbits in dynamical systems
In this work we study dynamical systems possessing Hamiltonian and time-reversible structures. The reversibility concept is de¯ned in terms of an involution. Initially we discuss the dynamics of Hamiltonian vector ¯elds with 2 and 3 degrees of freedom around an elliptic equilibrium in the presence of an involution which preserves the symplectic structure.
Publicado em: 2008
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6. Movimentos sob atração focal em campos vetoriais planares / Motions under focal attraction in planar vector fields
In this work, we develop the article On the motion under focal attraction in a rotating medium, of J. Sotomayor, which deals with a bidimensional differential system that model the following Biological problem: in a shallow recipient with circular section, with liquid in, spinning with angular speed ω, there are platyhelminthes, flatworms organisms, the
Publicado em: 2008
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7. Sobre a natureza dos processos físicos de aquecimento da atmosfera de estrelas do tipo solar
In the present work, we have studied the nature of the physical processes of the coronal heating, considering as basis significant samples of single and binary evolved stars, that have been achieved with the ROSAT satellite. In a total of 191 simple stars were studied, classified in the literature as giants with spectral type F, G and K. The resu
Publicado em: 2008
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8. Orbital maneuvers between the Lagrangian points and the primaries in the Earth-Sun system
This paper is concerned with trajectories to transfer a spacecraft between the Lagrangian points of the Sun-Earth system and the primaries. The Lagrangian points have important applications in astronautics, since they are equilibrium points of the equation of motion and very good candidates to locate a satellite or a space station. The planar circular restri
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2006-06
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9. Retrograde orbits perturbed by a third-body
This paper develops a semi-analytical study of the perturbation caused to a spacecraft by a third body involved in the dynamics. There are several important applications for this research, such as to calculate the effect of lunar and solar perturbations on high-altitude Earth satellites. In the present research the goal is to study the evolution of retrograd
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2005-12
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10. Numerical computation of optimal low-thrust limited-power trajectories - Transfers between coplanar circular orbits
An algorithm based on gradient techniques, proposed in a companion paper, is applied to numerical analysis of optimal low-thrust limited-power trajectories for simple transfer (no rendezvous) between coplanar circular orbits in a central Newtonian gravity field. The proposed algorithm combines the main positive characteristics of two well-known methods in op
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2005-06
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11. MÃtodos variacionais e soluÃÃes periÃdicas minimizantes para os problemas de Kepler, 3 e 4 corpos
In this dissertation, we make an introduction to the variational methods with intention of finding minimum of certain functionals. In particular, the minimum of the action function, are solutions of the N-body problem if they donât collisions. We study the minimum of the action functional for the Kepler problem, where we have check that on certain spaces th
Publicado em: 2005
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12. Transferência orbitais envolvendo órbitas do tipo halo / Transfers involving orbits of type halo
In space activities, it is of great importance the study of trajectories that the space vehicles should follow to complete a mission. In the present work, maneuvers involving Halo orbits for several systems of primary are studied. To accomplish this study the method of Lindstedt-Poincaré is used for the etermination of the orbits and the method of Lambert i
Publicado em: 2004