Results 261 to 270 of about 61,418 (298)

Modeling and forecast of the polar motion excitation functions for short-term polar motion prediction

Journal of Geodesy, 2004
Short-term forecast of the polar motion is considered by introducing a prediction model for the excitation function that drives the polar motion dynamics. The excitation function model consists of a slowly varying trend, periodic modes with annual and several sub-annual frequencies (down to the 13.6-day fortnightly tidal period), and a transient decay ...
T.M. Chin, R.S. Gross, J.O. Dickey
exaly   +2 more sources

Modeling the polar motion of Titan

Icarus, 2016
The angular momentum of the atmosphere and of the hydrocarbon lakes of Titan have a large equatorial component that can excite polar motion, a variable orientation of the rotation axis of Titan with respect to its surface. We here use the angular momentum obtained from a General Circulation Model of the atmosphere of Titan and from an Ocean Circulation
Coyette, Alexis, Van Hoolst, Tim, Baland, Rose-Marie, Tokano, Tetsuya   +3 more
openaire   +2 more sources

Polarization contrast and motion detection

Journal of Comparative Physiology A, 2006
Form and motion perception rely upon the visual system's capacity to segment the visual scene based upon local differences in luminance or wavelength. It is not clear if polarization contrast is a sufficient basis for motion detection. Here we show that crayfish optomotor responses elicited by the motion of images derived from spatiotemporal variations
Raymon M, Glantz, John P, Schroeter
openaire   +2 more sources

On secular polar motion

Chinese Astronomy and Astrophysics, 1981
Abstract Using the auto-regressive technique, we have analysed data of polar motion, Earth's rotation and excitation function of Earth's atmosphere and obtained their low frequency spectra. These spectra have some periods in common and this fact suggests that these periods are probably real.
Ming Zhao, Da-wei Zheng
openaire   +1 more source

“Polar”-functions for Brownian motion

Zeitschrift für Wahrscheinlichkeitstheorie und Verwandte Gebiete, 1982
Let (Xt)t≧0 denote the 2-dimensional Brownian motion. It is well-known that iff∶R+ →R2 is a constant function, then $$P\{ \exists t > 0\,X_t + f(t) = 0\} = 0.$$
openaire   +2 more sources

The Motion of Slow Electrons in a Polar Crystal

Physical Review, 1953
A variational technique is developed to investigate the low-lying energy levels of a conduction electron in a polar crystal. Because of the strong interaction between the electron and the longitudinal optical mode of the lattice vibrations, perturbation-theoretic methods are inapplicable.
Lee, T. D., Low, F. E., Pines, D.
openaire   +1 more source

DORIS and the Determination of the Earth’s Polar Motion

Journal of Geodesy, 2006
DORIS (Determination d’Orbite et Radiopositionnement Integres par Satellite) is a system used for precise orbit determination (POD) and ground-station positioning. It has been implemented on-board various satellites: the SPOT (Systeme pour l’Observation de la Terre) remote sensing satellites SPOT-2, SPOT-3, SPOT-4, SPOT-5, TOPEX/Poseidon and more ...
openaire   +3 more sources

Polarization vision in crayfish motion detectors

Journal of Comparative Physiology A, 2008
Motion detector interneurons were examined to determine their responsiveness to the motion of polarized light images (i.e. images segmented by spatial variations in e-vector angle). Computer generated images were displayed as intensity contrasts or polarization contrasts on a modified LCD projection panel.
openaire   +2 more sources

Theories of Notation and Polar Motion I,

1980
Abstract : The present report attempts a systematic presentation and review of modern theories of the earth's rotation (precession, nutation, and polar motion) for a rigid earth, a purely elastic earth, and the Poincare model consisting of a rigid mantle and a liquid core.
openaire   +1 more source

Motion Detection and Digital Polarization

2013
Flying insects have extraordinary visual capabilities. Their ability to detect fast motion in the visual scene and avoid collision using low level image processing and little computational power makes their visual processing interesting for real time motion/collision detection in machine vision applications.
Mukul Sarkar, Albert Theuwissen
openaire   +1 more source