Orbits
Mostrando 13-24 de 185 artigos, teses e dissertações.
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13. Dynamic pull-in instability of geometrically nonlinear actuated micro-beams based on the modified couple stress theory
This paper investigates the dynamic pull-in instability of vibrating micro-beams undergoing large deflection under electrosatically actuation. The governing equation of motion is derived based on the modified couple stress theory. Homotopy Perturbation Method is employed to produce the high accuracy approximate solution as well as the second-order frequency-
Lat. Am. j. solids struct.. Publicado em: 2014-10
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14. Spectroscopy analyses of polyurethane/polyaniline IPN using computational simulation (Amber, MM+ and PM3 method)
The polyurethane (PU)/polyaniline (PANI) IPN, at three composition ratios (95/05, 75/25, 60/40), were analyzed, after the action of the urease enzyme, by means of the Hyperchem 8v software. Theoretical analysis of Gibbs free energy, FTIR, and 13C-NMR were done. The generation of functional groups due to hydrolysis was analyzed by FTIR. The 13C-NMR spectra of
Polímeros. Publicado em: 2014-08
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15. 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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16. Thermal Protection System and Trajectory Optimization for Orbital Plane Change Aeroassisted Maneuver
ABSTRACT: The aim of this paper was to identify, for a specific maneuver, the optimal combination between the trajectory and the associated heat shield configuration, namely the locations and thicknesses of the ablative and reusable zones, that maximize the allowable payload mass for a spacecraft. The analysis is conducted by considering the coupling between
J. Aerosp. Technol. Manag.. Publicado em: 2013-03
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17. Facial reconstruction: measurement of the soft tissue´s thickness that covers the face / Reconstrução facial: mensuração da espessura dos tecidos moles que recobrem a face
Reconstrução facial forense é uma técnica utilizada com a finalidade de reconhecimento e posterior identificação, nas situações em que inexiste uma identidade atribuível ao esqueleto submetido à perícia médico-legal. Objetivou-se neste estudo mensurar as espessuras de tecidos moles que recobrem a face em cadáveres que deram entrada no Instituto
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 06/08/2012
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18. Existência e estabilidade de órbitas periódicas da Equação de Van der Pol-Mathieu / Existence and stability of periodic orbits of van der Pol-Mathieu equation
Neste trabalho alguns resultados sobre existência e estabilidade de soluções periódicas da equação de van der Pol-Mathieu são estudados. Por meio do Teorema da Média é provado, sob condições adequadas, que esta equação possui duas órbitas periódicas assintóticamente estáveis. Além disso é obtida a existência de cônicas invariantes no pla
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 28/02/2012
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19. Pointing Algorithm for Reentry Orbit Injection with Uncontrolled Last Stage
Abstract: An essencial requirement for a launcher with uncontrolled last stage is to compute the ignition time of that stage and its attitude, in order to obtain a proper orbit transfer from a nonpropelled trajectory to a desired orbit, since such stage it cannot change its velocity profile and its direction. This article presents an algorithm that allows ac
J. Aerosp. Technol. Manag.. Publicado em: 2012-09
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20. Predicting dysthyroid optic neuropathy using computed tomography volumetric analyses of orbital structures
OBJECTIVE: To evaluate the ability of orbital apex crowding volume measurements calculated with multidetector-computed tomography to detect dysthyroid optic neuropathy. METHODS: Ninety-three patients with Graves' orbitopathy were studied prospectively. All of the patients underwent a complete neuro-ophthalmic examination and computed tomography scanning. Vol
Clinics. Publicado em: 2012-08
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21. 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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22. Construction of Lyapunov functions for the estimation of basins of attraction
Technical systems are often modeled through systems of differential equations in which the parameters and initial conditions are subject to uncertainties. Usually, special solutions of the differential equations like equilibrium positions and periodic orbits are of importance and frequently the corresponding equations are only set up with the intent to descr
J. Braz. Soc. Mech. Sci. & Eng.. Publicado em: 2012
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23. Stochastic modeling of flexible rotors
Flexible rotors are characterized by inherent uncertainties affecting the parameters that influence the dynamic responses of the system. In this context, the handling of variability in rotor dynamics is a natural and necessary extension of the modeling capability of the existing techniques of deterministic analysis. Among the various methods used to model un
J. Braz. Soc. Mech. Sci. & Eng.. Publicado em: 2012
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24. La construcción de metáforas y adjetivaciones sobre la enfermedad en la prensa escrita: el caso de la epidemia de dengue en Córdoba durante abril de 2009
During April 2009, the phenomenon of dengue emerged in the city of Cordoba (Argentina). It was in this period that the first wave of autochthonous cases was triggered. Sociologically, it is interesting to investigate the various meanings that circulated around the disease, as they signal the marks that were given at the beginning of the epidemic. The objecti
Saúde e Sociedade. Publicado em: 2011-03