150 research outputs found
Finding Correspondences Between Images using Descriptors and Graphs
AbstractThe problem of finding correspondences is considered in the article. The main objective of this method is to reduce the number of false matches by using structural performance. The relevance of the problem is proven. The review of existing methods of finding correspondences is provided. The method presented is finding correspondences based on combined use of graphs and descriptors. Scott and Longuet-Higgins algorithm is used in the first stage. We construct a graph the vertices of which are the features on the two images. Singular value decomposition of the graph matrix is performed. The correspondences based on the descriptor are used. An example of the algorithm is shown. Test images are researched. A comparison of the algorithm with the RANSAC is carried out. The proposed approach allows excluding a significant portion of false correspondences found using the existing descriptors. The algorithm has high speed
Anisotropic lattice softening near the structural phase transition in the thermosalient crystal 1,2,4,5-tetrabromobenzene
Mechanism of crystal jumping on heating was revealed by X-ray diffraction and computational techniques.</p
Explicit asymptotic modelling of transient Love waves propagated along a thin coating
The official published version can be obtained from the link below.An explicit asymptotic model for transient Love waves is derived from the exact equations of anti-plane elasticity. The perturbation procedure relies upon the slow decay of low-frequency Love waves to approximate the displacement field in the substrate by a power series in the depth coordinate. When appropriate decay conditions are imposed on the series, one obtains a model equation governing the displacement at the interface between the coating and the substrate. Unusually, the model equation contains a term with a pseudo-differential operator. This result is confirmed and interpreted by analysing the exact solution obtained by integral transforms. The performance of the derived model is illustrated by numerical examples.This work is sponsored by the grant from Higher Education of Pakistan and by the Brunel University’s “BRIEF” research award
Propagation of perturbations along strings
A covariant formalism for physical perturbations propagating along a string
in an arbitrary curved spacetime is developed. In the case of a stationary
string in a static background the propagation of the perturbations is described
by a wave-equation with a potential consisting of 2 terms: The first term
describing the time-dilation and the second is connected with the curvature of
space. As applications of the developed approach the propagation of
perturbations along a stationary string in Rindler, de Sitter, Schwarzschild
and Reissner-Nordstrom spacetimes are investigated.Comment: 18 pages, LaTeX, Nordita-93/17
Giant Late Pleistocene paleolake in Central Kamchatka depression (Kamchatka Peninsula, Russian Far East)
A number of tephrochronologically correlated and dated sedimentary sections provide evidence for the existence of a giant lake filled the Central Kamchatka depression 30-11 thousand years ago. The lake extent bounded by CKD borders is estimated to be ~10 000 km2. This estimate makes this lake comparable in size to the famous Late Pleistocene glacial Lake Missoula
Stability of trapped Bose-Einstein condensates
In three-dimensional trapped Bose-Einstein condensate (BEC), described by the
time-dependent Gross-Pitaevskii-Ginzburg equation, we study the effect of
initial conditions on stability using a Gaussian variational approach and exact
numerical simulations. We also discuss the validity of the criterion for
stability suggested by Vakhitov and Kolokolov. The maximum initial chirp
(initial focusing defocusing of cloud) that can lead a stable condensate to
collapse even before the number of atoms reaches its critical limit is obtained
for several specific cases. When we consider two- and three-body nonlinear
terms, with negative cubic and positive quintic terms, we have the conditions
for the existence of two phases in the condensate. In this case, the magnitude
of the oscillations between the two phases are studied considering sufficient
large initial chirps. The occurrence of collapse in a BEC with repulsive
two-body interaction is also shown to be possible.Comment: 15 pages, 11 figure
Strong coupling constant from decay within renormalization scheme invariant treatment
We extract a numerical value for the strong coupling constant \alpha_s from
the \tau-lepton decay rate into nonstrange particles. A new feature of our
procedure is the explicit use of renormalization scheme invariance in
analytical form in order to perform the actual analysis in a particular
renormalization scheme. For the reference coupling constant in the
\MSsch-scheme we obtain \alpha_s(M_\tau)= 0.3184 \pm 0.0060_{exp} which
corresponds to \al_s(M_Z)= 0.1184 \pm 0.0007_{exp} \pm 0.0006_{hq mass}. This
new numerical value is smaller than the standard value from -data quoted
in the literature and is closer to \al_s(M_Z)-values obtained from high energy
experiments.Comment: 8 page
Sinh-Gordon, Cosh-Gordon and Liouville Equations for Strings and Multi-Strings in Constant Curvature Spacetimes
We find that the fundamental quadratic form of classical string propagation
in dimensional constant curvature spacetimes solves the Sinh-Gordon
equation, the Cosh-Gordon equation or the Liouville equation. We show that in
both de Sitter and anti de Sitter spacetimes (as well as in the black
hole anti de Sitter spacetime), {\it all} three equations must be included to
cover the generic string dynamics. The generic properties of the string
dynamics are directly extracted from the properties of these three equations
and their associated potentials (irrespective of any solution). These results
complete and generalize earlier discussions on this topic (until now, only the
Sinh-Gordon sector in de Sitter spacetime was known). We also construct new
classes of multi-string solutions, in terms of elliptic functions, to all three
equations in both de Sitter and anti de Sitter spacetimes. Our results can be
straightforwardly generalized to constant curvature spacetimes of arbitrary
dimension, by replacing the Sinh-Gordon equation, the Cosh-Gordon equation and
the Liouville equation by higher dimensional generalizations.Comment: Latex, 19 pages + 1 figure (not included
- …