Results 201 to 210 of about 4,169 (241)

Estimating evaporation duct heights from radar sea echo

Radio Science, 2000
The evaporation duct is a downward refracting layer that results from the rapid decrease in humidity with respect to altitude occurring in the atmospheric surface layer above bodies of water. The evaporation duct affects radar detection ranges at frequencies of approximately 1 GHz and above.
L. Ted Rogers, Claude P. Hattan, Janet K. Stapleton   +2 more
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The transient response above an evaporation duct

Journal of Physics D: Applied Physics, 1998
The transient electromagnetic field generated by a vertical electric dipole above an evaporation duct is investigated theoretically. The evaporation duct model used is that previously described by Kahan and Eckart. A vertical electric dipole, above the surface layer, is taken as the source of the electromagnetic field. We determine the electrical field
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Failure of large-scale pilot evaporator duct nozzle

Engineering Failure Analysis, 2015
Abstract Failure investigation was carried out on a 12'' water evaporator duct nozzle of a large-scale steam flood pilot which is used to inject steam into a heavy crude oil reservoir. The nozzle contained cracks at the pipe, shell, pad and welds. All the materials are made of UNS31803 grade 2205 duplex stainless steel.
H.M. Shalaby, B. Al-Wakaa, N. Tanoli
openaire   +1 more source

94-GHz propagation in the evaporation duct

IEEE Transactions on Antennas and Propagation, 1990
One-way, low-altitude radio propagation measurements at 94 GHz and simultaneous surface meteorological measurements were made on a 40.6 km, over-horizon, over-water path along the southern California coast to assess the effects of the evaporation duct on signal propagation.
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Evaporation duct estimation from clutter using meteorological statistics

2008 IEEE Antennas and Propagation Society International Symposium, 2008
Many of the lower atmospheric maritime radar systems have to operate under ducting conditions. Electromagnetic ducts result in non-standard electromagnetic propagation which can fundamentally change the performance of the system that is designed to operate under standard atmospheric conditions.
C. Yardim, P. Gerstoft, W.S. Hodgkiss
openaire   +1 more source

Propagation Theory for the Evaporation Duct

1973
Propagation in radio ducts first attracted attention during the 1940’s and was the subjectof some notable theoretical studies (1),(2),(3).Recent developments such as the use of the Monin-Obukhov similarity theory(4) to give realistic refractive index models, improvements in theoretical and numerical methods and the need to incorporate other phenomena ...
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Practical application of an evaporation duct model

Radio Science, 1985
The application of an evaporation duct model in operational and climatological assessments of propagation and the sensitivity of the model to meteorological measurements are examined. The unexpectedly frequent occurrence of evaporation duct heights greater than 40 m is related to thermally stable conditions in the atmospheric surface layer.
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Influence of evaporation ducts on radar sea return

IEE Proceedings F Radar and Signal Processing, 1990
Modelling of radar sea return is discussed with consideration of propagation conditions. Both the intensity and propagation direction of energy incident at the sea surface can be significantly affected by the refractive condition of the atmosphere. The authors describe and evaluate a model that incorporates both of these effects for the situation where
J.P. Reilly, G.D. Dockery
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Evaporation ducts observed during the TAPS 2013 campaign

2015 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), 2015
The Tropical Air-Sea Propagation Study (TAPS) was an experimental campaign that took place in the northern coast of Queensland, Australia between the 25th of November and 5th of December 2013. The main objectives of TAPS concern the validation of mesoscale NWP models (including surface layer models) in a tropical littoral environment and also the ...
Claverie, Jacques, Hurtaud, Yvonick, Periard, Christophe, Pourret, Vivien, Kulessa, Andy   +4 more
openaire   +2 more sources

Simulation of microwave propagation in turbulent evaporation duct

2012 6th European Conference on Antennas and Propagation (EUCAP), 2012
The method to account for turbulent refractivity fluctuations for split-step parabolic equation Fourier method are presented. The results of microwave propagation simulations in an evaporation duct with account for scattering by correlated turbulent fluctuations of the tropospheric refractivity index is analyzed.
Iurii Levadnyi, Victor Ivanov, Vyacheslav Shalyapin   +2 more
openaire   +1 more source