Spatial structure of low-frequency wind noise

2007 ◽  
Vol 122 (6) ◽  
pp. EL223-EL228 ◽  
Author(s):  
D. Keith Wilson ◽  
Roy J. Greenfield ◽  
Michael J. White
Keyword(s):  
Spatial Structure ◽  
Low Frequency ◽  
Wind Noise

scholarly journals Frequency and plasma condition dependent spatial structure of low frequency global potential oscillations in the TJ-II stellarator

2019 ◽  
Vol 59 (4) ◽  
pp. 044006 ◽  
Author(s):  
T. Kobayashi ◽  
U. Losada ◽  
B. Liu ◽  
T. Estrada ◽  
B.Ph. van Milligen ◽  
...  
Keyword(s):  
Spatial Structure ◽  
Low Frequency ◽  
Plasma Condition ◽  
Potential Oscillations

Low frequency wind noise contributions in measurement microphones

2008 ◽  
Vol 123 (3) ◽  
pp. 1260-1269 ◽  
Author(s):  
Richard Raspet ◽  
Jiao Yu ◽  
Jeremy Webster
Keyword(s):  
Low Frequency ◽  
Wind Noise

Spatial structure of long‐range, low‐frequency seafloor reverberation in the Canary Basin

1990 ◽  
Vol 88 (S1) ◽  
pp. S106-S106
Author(s):  
Jonathan M. Berkson ◽  
Fredrick R. Facemire ◽  
Jay A. Wallmark
Keyword(s):  
Spatial Structure ◽  
Long Range ◽  
Low Frequency

Calculations of low-frequency wind noise along a low two-dimensional hill surface

2018 ◽  
Vol 144 (3) ◽  
pp. 1679-1679
Author(s):  
Gregory W. Lyons ◽  
Carl R. Hart
Keyword(s):  
Low Frequency ◽  
Two Dimensional ◽  
Wind Noise

Wind Noise Reduction for Outdoor Measurement Microphones With Windscreens

2008 ◽  
Author(s):  
Z. C. Zheng ◽  
Ying Xu
Keyword(s):  
Noise Reduction ◽  
High Frequency ◽  
Low Frequency ◽  
High Flow ◽  
Low Flow ◽  
Computational Techniques ◽  
Wind Noise ◽  
Flow Resistivity ◽  
Materials Used ◽  
Wind Noise Reduction

In this study, effects of windscreen material property on wind noise reduction are investigated at different frequencies of incoming wind turbulence. The properties of porous materials used for the windscreen are represented by flow resistivity. Computational techniques are developed to study the detailed flow around the windscreen as well as flow inside the windscreen that uses a porous material as the medium. The coupled simulation shows that for low-frequency turbulence, the windscreens with low flow resistivity are more effective in noise reduction. Contrarily, for high-frequency turbulence, the windscreens with high flow resistivity are more effective.

Low‐frequency wind noise reduction by spherical windscreens

2007 ◽  
Vol 121 (5) ◽  
pp. 3063-3063 ◽  
Author(s):  
Richard Raspet ◽  
Jeremy Webster ◽  
Jiao Yu
Keyword(s):  
Noise Reduction ◽  
Low Frequency ◽  
Wind Noise ◽  
Wind Noise Reduction

scholarly journals Modulation of radio frequency signals by ULF waves

2007 ◽  
Vol 25 (5) ◽  
pp. 1113-1124 ◽  
Author(s):  
C. L. Waters ◽  
T. K. Yeoman ◽  
M. D. Sciffer ◽  
P. Ponomarenko ◽  
D. M. Wright
Keyword(s):  
Spatial Structure ◽  
Radio Frequency ◽  
Wave Energy ◽  
Ionospheric Plasma ◽  
Low Frequency ◽  
Radar Data ◽  
Hf Radar ◽  
Ulf Waves ◽  
Ulf Wave ◽  
Magnetometer Arrays

Abstract. The ionospheric plasma is continually perturbed by ultra-low frequency (ULF; 1–100 mHz) plasma waves that are incident from the magnetosphere. In this paper we present a combined experimental and modeling study of the variation in radio frequency of signals propagating in the ionosphere due to the interaction of ULF wave energy with the ionospheric plasma. Modeling the interaction shows that the magnitude of the ULF wave electric field, e, and the geomagnetic field, B0, giving an e×B0 drift, is the dominant mechanism for changing the radio frequency. We also show how data from high frequency (HF) Doppler sounders can be combined with HF radar data to provide details of the spatial structure of ULF wave energy in the ionosphere. Due to spatial averaging effects, the spatial structure of ULF waves measured in the ionosphere may be quite different to that obtained using ground based magnetometer arrays. The ULF wave spatial structure is shown to be a critical parameter that determines how ULF wave effects alter the frequency of HF signals propagating through the ionosphere.

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