Results 141 to 150 of about 711,225 (168)

EMI potential of radiowaves in presence of atmospheric ducts

International Journal of Electronics, 1990
Radiowave propagation measurements were conducted over a smooth-Earth diffraction path (35 km) between Roorkee and Saharanpur for a period of one year. The data collected were analysed with a view to contribute to the understanding of the propagation phenomenon involved and to provide some physical basis for the prediction techniques to be considered ...
R. K. TEWARI, B. S. JASSAL, M. N. ROY
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Predicting Duct Height in Atmospheric Duct by Neural Network

Advanced Materials Research, 2012
The experimental data show that Southeast China Sea has a higher occurrence probability of atmospheric duct. Based on modified refractivity, Neural Network was introduced to predict the duct height of evaporation duct and analyze the anomalous propagation of electromagnetic wave in marine evaporation duct.
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Analysis of Missing Cloud Echoes in Atmospheric Duct

2019 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC), 2019
In order to analyze the phenomenon of missing cloud echoes of doppler weather radar in Dalian in July 25, 2006, the atmospheric duct is calculated by using the atmospheric temperature and humidity profiles measured at that time. According to the calculated atmospheric duct, the parabolic numerical equation model and radar cloud echo detection distance ...
Hua Wang, Yunbo Li, Haichuan Tang, Lin Jiao   +3 more
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Prediction of Electromagnetic Shadow Zone in Atmospheric Duct

The 2006 4th Asia-Pacific Conference on Environmental Electromagnetics, 2006
Electromagnetic shadow zone is an important propagation character which is caused by atmospheric duct. The purpose of this paper is to find a method to predict such shadow zone. Two numerical models are introduced in this paper. The first one is used to predict the top hole in evaporation duct. The other one is to predict the skip zone in surface duct.
Jiao Lin, Wang Hua, Zhang Yong-gang
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The operating characteristics of a ducted rocket in the Mars atmosphere

46th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2010
The Mars vehicle which can fly in the Mars atmosphere is necessary to do detailed surveys of the surface of Mars. This vehicle needs a propulsion engine which can work in the Mars atmosphere, mainly consisting of carbon dioxide. The ducted rocket is effective as propulsion engine, because it uses carbon dioxide as an oxidizer and combusts metal as fuel.
Masamichi Ushijima, Hideki Hara, Akinori Muramatsu, Takuo Kuwahara   +3 more
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Design of an ocean atmospheric duct signal processor

2010 International Symposium on Intelligent Signal Processing and Communication Systems, 2010
The atmospheric refractive section plane retrieved from radar sea clutter is of importance for the might enhancement of military naval radar. In this paper, an atmospheric duct signal processor with hardware of an intermediate-frequency board and a high-speed DSP board, besides the arithmetic of clutter suppression and sea clutter extraction, have been
null Li XueHua, null He ZiShu, null He JianXin, null Duan ShouYuan   +3 more
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Trends and frontiers of atmospheric duct research based on CiteSpace and deep learning

Environmental Science and Pollution Research, 2022
The research of evaporation duct is of fundamental importance in the radar and signal communication industry. Particularly, in a real atmosphere environment, most of the radar holes cannot be corrected in time because of the persistent evaporation duct phenomenon.
Jiajing, Wu, Zhiqiang, Wei, Jinpeng, Zhang, Jiali, Xu, Dongjing, Jia, Hanjie, Ji   +5 more
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Ducted Acoustic Gravity Waves in a Nearly Isothermal Atmosphere

The Journal of the Acoustical Society of America, 1967
The propagation of acoustic gravity waves is analyzed in atmospheres that have vertical profiles of sound speed squared of the form c2(z) = c2(∞)±Δc2e−2/l, where c2(∞)≫Δc2>0, and both c2(∞) and Δc2 are constant. Ducted wave dispersion relations are obtained from the requirements that the earth's surface act as a rigid boundary to the atmospheric
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A narrow-angle parabolic equation model in atmospheric ducts

2016 11th International Symposium on Antennas, Propagation and EM Theory (ISAPE), 2016
In this paper, the narrow-angle parabolic equation (NAPE) model applied on atmospheric ducts is solved by using the improved discrete mixed Fourier transform (IDMFT) method which is an efficient form of the split-step Fourier transform (SSFT) algorithm under the impedance boundary conditions.
Yajiao Wang, Lixin Guo, Qingliang Li
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Ducted propagation in the atmosphere, from audible sound to infrasound.

The Journal of the Acoustical Society of America, 2010
Earth’s atmosphere supports complicated and highly variable winds and temperature gradients. Temperature inversions and wind jets provide ducts in which sound can propagate efficiently to great distances from the source. Due to the intrinsic variability of the atmospheric winds, these sound ducts are also quite variable, both temporally and spatially ...
Roger Waxler, Carrick Talmadge, Kenneth Gilbert, Xiao Di, Phillip Blom, Jelle Assink, Claus Hetzer   +6 more
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