نتایج جستجو برای: isotropy

تعداد نتایج: 2204  

2010
RICHARD MELROSE

A refined form of the ‘Folk Theorem’ that a smooth action by a compact Lie group can be (canonically) resolved, by iterated blow up, to have unique isotropy type is proved in the context of manifolds with corners. This procedure is shown to capture the simultaneous resolution of all isotropy types in a ‘resolution structure’ consisting of equivariant iterated fibrations of the boundary faces. T...

2008
John D. Barrow Hideo Kodama

We discuss the problem of the stability of the isotropy of the universe in the space of ever-expanding spatially homogeneous universes with a compact spatial topology. The anisotropic modes which prevent isotropy being asymptotically stable in Bianchi-type V IIh universes with non-compact topologies are excluded by topological compactness. Bianchi type V and type V IIh universes with compact to...

2000
Alan Bowling Oussama Khatib

This article presents a new performance measure, the actuation eeciency, which describes isotropy in acceleration capability for non-redundant manipulators. It measures the imbalance between the end-eeector accelerations achievable in diierent directions. Prior to this, no measure of this characteristic was adequate for a six degree-of-freedom manipulator, because its end-eeector motions are re...

2006
Soumen Basak Amir Hajian Tarun Souradeep

We formulate statistical isotropy of CMB anisotropy maps in its most general form. We also present a fast and orientation independent statistical method to determine deviations from statistical isotropy in CMB polarization maps. Importance of having statistical tests of departures from SI for CMB polarization maps lies not only in interesting theoretical motivations but also in testing cleaned ...

2010
Haoxuan Zheng Emory F. Bunn

Several anomalies appear to be present in the large-angle cosmic microwave background anisotropy maps of the Wilkinson Microwave Anisotropy Probe, including the alignment of large-scale multipoles. Models in which isotropy is spontaneously broken (e.g., by a scalar field) have been proposed as explanations for these anomalies, as have models in which a preferred direction is imposed during infl...

2007
U. Gran G. Papadopoulos D. Roest P. Sloane

We find the geometry of all supersymmetric type I backgrounds by solving the gravitino and dilatino Killing spinor equations, using the spinorial geometry technique, in all cases. The solutions of the gravitino Killing spinor equation are characterized by their isotropy group in Spin(9, 1), while the solutions of the dilatino Killing spinor equation are characterized by their isotropy group in ...

2009
IAN HAMBLETON

We introduce a new construction, the isotropy groupoid, to organize the orbit data for split Γ-spaces. We show that equivariant principal G-bundles over split Γ-CW complexes X can be effectively classified by means of representations of their isotropy groupoids. For instance, if the quotient complex A = Γ\X is a graph, with all edge stabilizers toral subgroups of Γ, we obtain a purely combinato...

2008
P - L. Buono M. Helmer J. S. W. Lamb

Let G be a finite group acting on vector spaces V and W and consider a smooth G-equivariant mapping f : V → W. This paper addresses the question of the zero set near a zero x of f with isotropy subgroup G. It is known from results of Bierstone and Field on G-transversality theory that the zero set in a neighborhood of x is a stratified set. The purpose of this paper is to partially determine th...

The governing equations of a transversely isotropic dissipative medium are solved analytically to obtain the surface wave solutions. The appropriate solutions satisfy the required boundary conditions at the stress-free surface to obtain the frequency equation of Rayleigh wave. The numerical values of the non-dimensional speed of Rayleigh wave speed are computed for different values of frequency...

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