The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Sergei A. Klioner - One of the best experts on this subject based on the ideXlab platform.
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analysis of astrometric catalogues with vector Spherical Harmonics
Astronomy and Astrophysics, 2012Co-Authors: Francois Mignard, Sergei A. KlionerAbstract:Aims. We compare stellar catalogues with position and proper motion components using a decomposition on a set of orthogonal vector Spherical Harmonics. We aim to show the theoretical and practical advantages of this technique as a result of invariance properties and the independence of the decomposition from a prior model. Methods. We describe the mathematical principles used to perform the spectral decomposition, evaluate the level of significance of the multipolar components, and examine the transformation properties under space rotation. Results. The principles are illustrated with a characterisation of systematic effects in the FK5 catalogue compared to Hipparcos and with an application to extraction of the rotation and dipole acceleration in the astrometric solution of QSOs expected from Gaia.
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Analysis of astrometric catalogues with vector Spherical Harmonics
Astronomy & Astrophysics, 2012Co-Authors: Francois Mignard, Sergei A. KlionerAbstract:Comparison of stellar catalogues with position and proper motion components using a decomposition on a set of orthogonal vector Spherical Harmonics. We show the theoretical and practical advantages of this technique as a result of invariance properties and the independence of the decomposition from a prior model. We describe the mathematical principles used to perform the spectral decomposition, evaluate the level of significance of the multipolar components and examine the transformation properties under space rotation. The principles are illustrated with a characterisation of the systematic effects in the FK5 catalogue compared to Hipparcos and with an application to the extraction of the rotation and dipole acceleration in the astrometric solution of QSOs expected from Gaia.
Jordi Marzo - One of the best experts on this subject based on the ideXlab platform.
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marcinkiewicz zygmund inequalities and interpolation by Spherical Harmonics
Journal of Functional Analysis, 2007Co-Authors: Jordi MarzoAbstract:Abstract We find necessary density conditions for Marcinkiewicz–Zygmund inequalities and interpolation for spaces of Spherical Harmonics in S d with respect to the L p norm. Moreover, we prove that there are no complete interpolation families for p ≠ 2 .
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marcinkiewicz zygmund inequalities and interpolation by Spherical Harmonics
arXiv: Functional Analysis, 2006Co-Authors: Jordi MarzoAbstract:We find necessary density conditions for Marcinkiewicz-Zygmund inequalities and interpolation for spaces of Spherical Harmonics with respect to the L^p norm. Moreover, we prove that there are no complete interpolation families for p\neq 2.
Wei Cai - One of the best experts on this subject based on the ideXlab platform.
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Spherical Harmonics method for computing the image stress due to a Spherical void
Journal of The Mechanics and Physics of Solids, 2019Co-Authors: Yifan Wang, Xiaohan Zhang, Wei CaiAbstract:Abstract We develop an efficient numerical method for calculating the image stress field induced by Spherical voids in materials, and applied the method to dislocation-void interactions. The method is constructed based on a complete set of basis functions for the displacement potential of the elastic boundary value problem for a Spherical hole, as well as the corresponding displacement, stress, and traction fields, all in terms of linear combinations of Spherical Harmonics. Using the fast transformation between the real and Spherical-Harmonics spaces provided by the SHTOOLS package, the method is more efficient than other image stress solvers such as the finite-element method. This method can be readily extended for solving elasticity problems involving inclusions and inhomogeneities, as well as contact between spheres. The tools developed here can also be useful for fast solution of differential equations with Spherical boundaries beyond elasticity.
C Yildiz - One of the best experts on this subject based on the ideXlab platform.
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the Spherical Harmonics method for anisotropic scattering in neutron transport theory the critical sphere problem
Journal of Quantitative Spectroscopy & Radiative Transfer, 2001Co-Authors: C YildizAbstract:Abstract The transport of one-speed neutrons has been studied in a homogeneous sphere with Marshak boundary conditions. The scattering function is assumed to be a combination of linearly anisotropic and strongly forward-backward scattering. Numerical results for the critical radius are obtained and tabulated for different scattering parameters using the Spherical Harmonics method. We have also obtained the numerical values of the critical radius in the range of 1/c⩽α, β⩽1. The results indicate that the radius varies monotonically with increasing anisotropy. The monotonic variation continues and limits to a non-zero value with an extreme forward bias and linear anisotropy. Finally, some results are discussed and compared with those already obtained by using various methods. It is shown that the Spherical Harmonics method gives generally accurate results and is easily applicable to this type of anisotropic scattering kernel.
Francois Mignard - One of the best experts on this subject based on the ideXlab platform.
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analysis of astrometric catalogues with vector Spherical Harmonics
Astronomy and Astrophysics, 2012Co-Authors: Francois Mignard, Sergei A. KlionerAbstract:Aims. We compare stellar catalogues with position and proper motion components using a decomposition on a set of orthogonal vector Spherical Harmonics. We aim to show the theoretical and practical advantages of this technique as a result of invariance properties and the independence of the decomposition from a prior model. Methods. We describe the mathematical principles used to perform the spectral decomposition, evaluate the level of significance of the multipolar components, and examine the transformation properties under space rotation. Results. The principles are illustrated with a characterisation of systematic effects in the FK5 catalogue compared to Hipparcos and with an application to extraction of the rotation and dipole acceleration in the astrometric solution of QSOs expected from Gaia.
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Analysis of astrometric catalogues with vector Spherical Harmonics
Astronomy & Astrophysics, 2012Co-Authors: Francois Mignard, Sergei A. KlionerAbstract:Comparison of stellar catalogues with position and proper motion components using a decomposition on a set of orthogonal vector Spherical Harmonics. We show the theoretical and practical advantages of this technique as a result of invariance properties and the independence of the decomposition from a prior model. We describe the mathematical principles used to perform the spectral decomposition, evaluate the level of significance of the multipolar components and examine the transformation properties under space rotation. The principles are illustrated with a characterisation of the systematic effects in the FK5 catalogue compared to Hipparcos and with an application to the extraction of the rotation and dipole acceleration in the astrometric solution of QSOs expected from Gaia.
