Results 111 to 120 of about 10,029 (146)

The radial velocity estimation based on digital spotlight technique

2015 IEEE 5th Asia-Pacific Conference on Synthetic Aperture Radar (APSAR), 2015
For synthetic aperture radar(SAR) imaging of ship targets, it's difficult to generate high quality images because their motion characteristics are blind in most cases. Aiming at this problem, this paper presents a processing scheme for estimating the radial velocity based on the digital spotlight processing.
Tianshun Xiang, Yong Li, Li Liu, Huajun Duan   +3 more
openaire   +1 more source

A Variational Technique for Dealiasing Doppler Radial Velocity Data

Journal of Applied Meteorology, 2004
Velocity folding, or aliasing, is one of most significant impediments to the use of radial winds from Doppler weather radar. In this note, a variational algorithm is developed in which dealiasing is performed using wind gradient information. The key to the proposed method is that, by operating on gradients of velocity rather than on the velocity itself,
Jidong Gao, Kelvin K. Droegemeier
openaire   +1 more source

Pushing Down the Limits of the Radial Velocity Technique

2008
We present results from the first three years of operations of the HARPS spectrograph installed on the ESO-3.6m telescope at La Silla Observatory, Chile. This instrument, primarily built to detect extrasolar planetary systems, has demonstrated a long-term accuracy below the 1 m s-1 level, exploring a new regime in RV precision and discovering several ...
C. Lovis, M. Mayor, F. Pepe, D. Queloz, S. Udry   +4 more
openaire   +1 more source

Lens mounting techniques for precise radial location of fragile lenses in the NGS2 and Veloce instruments

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III, 2018
We present novel methods for mounting lenses in a pair of instruments that presented challenging optical and mechanical requirements. The first instrument is the replacement Natural Guide Star Sensor (NGS2) for CANOPUS at Gemini South, which incorporates an objective consisting of a stack of six lenses mounted in a common bore.
James Gilbert, Francis Bennet, Ian Price, François Rigaut, Céline d'Orgeville, Nicholas Herrald   +5 more
openaire   +1 more source

Application of the Telluric-Line Technique to Study Late-Type Stars for Radial-Velocity Variations

International Astronomical Union Colloquium, 1999
AbstractAlthough the use of telluric lines as wavelength fiducials to measure radial velocities does not achieve as high a precision as other fiducial-imposition techniques, this very convenient technique can be used concurrently with other observing programs to increase the temporal sampling of target stars.
Robert Greimel, Stephenson L.S. Yang
openaire   +1 more source

Doppler radial velocity detection based on Doppler asymmetric spatial heterodyne spectroscopy technique for absorption lines*

Chinese Physics B, 2020
Doppler asymmetric spatial heterodyne spectroscopy (DASH) technique has developed rapidly in passive Doppler-shift measurements of atmospheric emission lines over the last decade. With the advantages of high phase shift sensitivity, compact, and rugged structure, DASH is proposed to be used for celestial autonomous navigation based on Doppler radial ...
Yin-Li Kuang, Liang Fang, Xiang Peng, Xin Cheng, Hui Zhang, En-Hai Liu   +5 more
openaire   +1 more source

Inversion technique to obtain local ion temperature profiles for an axisymmetric plasma with toroidal and radial velocities

Plasma Physics and Controlled Fusion, 2021
Abstract A matrix inversion technique is derived to calculate local ion temperature from line-integrated measurements of an extended emission source in an axisymmetric plasma which exactly corrects for both toroidal velocity and radial velocity components.
openaire   +1 more source

Radial artery pulse wave velocity: a new characterization technique and the instabilities associated with the respiratory phase and breath-holding

Physiological Measurement, 2023
Abstract Objective . Pulse wave velocity (PWV) is a key diagnostic parameter of the cardiovascular system’s state. However, approaches aimed at PWV characterization often suffer from inevitable drawbacks.
openaire   +2 more sources

A Quasi-Traditional Spectroscopic Radial Velocity Technique Applied to the Rotation of Venus

Nature, 1965
Photoelectric spectroscopic radial velocity technique to measure Venus rotation with ...
openaire   +1 more source

Radial strain and strain rate by two-dimensional speckle tracking echocardiography and the tissue velocity based technique in the dog

Journal of Veterinary Cardiology, 2007
Two-dimensional (2D) speckle tracking echocardiography (STE) is a new angle-independent ultrasound technique based on tracking of speckles within the myocardium on 2D grayscale images. The aims of this prospective study were as follows: (1) to assess the variability of left ventricular peak systolic radial strain (St) and strain rate (SR) in awake dogs
Valérie, Chetboul, Francois, Serres, Vassiliki, Gouni, Renaud, Tissier, Jean-Louis, Pouchelon   +4 more
openaire   +2 more sources