Results 271 to 280 of about 32,736 (313)

Atmospheric and laser propagation

Technologies for Optical Countermeasures XIV, 2017
This paper reviews three phenomena that affect the propagation of electro-optical radiation through the atmosphere: absorption and scattering, refraction and turbulence. The net effect on imaging or laser systems is a net reduction of the effective range, or a degradation of the information contained in the electro-optical radiation. Recent advances in
Eijk, A.M.J. van, Stein, K.
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The propagation of a radio atmospheric

Proceedings of the IEE - Part B: Radio and Electronic Engineering, 1956
On the assumption that the space between the earth and the ionosphere acts as a waveguide, the mechanism of propagation of an atmospheric has been considered from the viewpoint of plane-wave reflections. The pulse at the origin has been assumed to be rectangular and of duration 100 microsec.
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Atmospheric propagation modelling

The Journal of the Acoustical Society of America, 1997
With the developments in modeling the propagation of sound through the atmosphere, it is now possible to merge these models with sensor models to determine the impact of the atmosphere on acoustic sensor performance. Early numerical models such as the Fast-Field Program (FFP) allowed users to predict the effects of refraction, geometric spreading ...
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The Propagation of Atmospherics

1976
Fundamental problems in atmospherics research are sketched. Breaking the subject down into three natural divisions: sources, propagation medium, and receiving technology, it is shown that, as a rule, only a statistical analysis of the received impulses leads to interpretable and significant results, and that the propagation conditions in the ...
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Atmospheric effects on propagation

1985 Tenth International Conference on Infrared and Millimeter Waves, 1985
The potential benefits to be derived from the use of radiation at frequencies near 300GHz for ranging and imaging have been apparent for many years but, in part because of nonavailability of convenient sources and detectors, until recently little quantitative research on the effects of the atmosphere upon such radiation has been conducted outside the ...
P. C. Claspy, F. L. Merat
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New Experimental Data on Atmospheric Propagation

Science, 1979
An experiment has been performed to measure directly the effect of atmospheric turbulence on spherical wave propagation of light on a vertical path. The results permit determination of the magnitude of the effect at a variety of locations and under different conditions.
R R, Shannon, C, Ceccon, W S, Smith, W, Metheny, R, Philbrick   +4 more
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Propagation of tweek atmospherics

Journal of Atmospheric and Terrestrial Physics, 1978
Abstract In order to investigate the propagation mechanism of tweek atmospherics near mode cut-off frequencies, the attenuation coefficient and excitation factor of the Earth-ionosphere waveguide are calculated for both quasitransverse magnetic (QTM) and quasitransverse electric (QTE) modes.
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Optical Propagation through the Atmosphere

1991
Questo articolo è il capitolo 19 di 34 capitoli, ciascuno scritto da un eminente esperto nel proprio argomento, che J. Goodmann ha raccolto in un volume promosso dall'ICO ( International Commission for Optics) allo scopo di descrivere la situazione presente della ricerca in ottica a livello mondiale.
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Sound Propagation in the Atmosphere

1951
Velocity of Sound. The velocity C with which a change in volume is propagated in a material with Lame’s constants λ and μ, and with the density ρ is given by (1)
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Atmospheric Optical Propagation

2007
Abstract : The Atmospheric Optical Propagation project is developing a suite of accurate models for optical propagation in the marine atmospheric boundary layer. Our objective is to provide an atmospheric effects characterization package for existing and emerging Navy applications.
Alexander M. Van Eijk, Dimitri Tsintikidis, Stephen Hammel   +2 more
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