Far-field radiation of a vibrating point source in anisotropic media

1991 ◽  
Vol 10 (2) ◽  
pp. 71-78 ◽  
Author(s):  
Kunyu Wu ◽  
Peter B. Nagy ◽  
Laszlo Adler
Keyword(s):  
Point Source ◽  
Anisotropic Media ◽  
Far Field ◽  
Field Radiation

The shape of things to come — Development and testing of a new marine vibrator source

2019 ◽  
Vol 38 (9) ◽  
pp. 680-690 ◽  
Author(s):  
Benoît Teyssandier ◽  
John J. Sallas
Keyword(s):  
Seismic Source ◽  
Test Facility ◽  
Data Sets ◽  
Far Field ◽  
Ocean Bottom ◽  
Air Gun ◽  
Seismic Image ◽  
Field Radiation ◽  
Technical Issues ◽  
To Come

Ten years ago, CGG launched a project to develop a new concept of marine vibrator (MV) technology. We present our work, concluding with the successful acquisition of a seismic image using an ocean-bottom-node 2D survey. The expectation for MV technology is that it could reduce ocean exposure to seismic source sound, enable new acquisition solutions, and improve seismic data quality. After consideration of our objectives in terms of imaging, productivity, acoustic efficiency, and operational risk, we developed two spectrally complementary prototypes to cover the seismic bandwidth. In practice, an array composed of several MV units is needed for images of comparable quality to those produced from air-gun data sets. Because coupling to the water is invariant, MV signals tend to be repeatable. Since far-field pressure is directly proportional to piston volumetric acceleration, the far-field radiation can be well controlled through accurate piston motion control. These features allow us to shape signals to match precisely a desired spectrum while observing equipment constraints. Over the last few years, an intensive validation process was conducted at our dedicated test facility. The MV units were exposed to 2000 hours of in-sea testing with only minor technical issues.

The far-field scattering response of a side drilled hole in single/layered anisotropic media in ultrasonic pulse-echo setup

Wave Motion ◽  
2011 ◽  
Vol 48 (3) ◽  
pp. 275-289 ◽  
Author(s):  
Jing Ye ◽  
Hak-Joon Kim ◽  
Sung-Jin Song ◽  
Sung-Sik Kang ◽  
Kyungcho Kim ◽  
...  
Keyword(s):  
Anisotropic Media ◽  
Ultrasonic Pulse ◽  
Far Field ◽  
Scattering Response ◽  
Pulse Echo

Radiation from supersonic faulting

1971 ◽  
Vol 61 (4) ◽  
pp. 1009-1012 ◽  
Author(s):  
J. C. Savage
Keyword(s):  
Initial Point ◽  
Step Function ◽  
Fault Model ◽  
Dislocation Segment ◽  
Far Field ◽  
Fault Propagation ◽  
Unit Step ◽  
Propagation Factor ◽  
Double Couple ◽  
Field Radiation

abstract The far-field radiation from a simple fault model is given by the radiation pattern associated with the appropriate strain nucleus (e.g., double couple) multiplied by a fault propagation factor. For a unilateral fault model the propagation factor is F ( c ; t ) = ζ bd [ H ( τ ) − H ( τ − ( L / ζ ) ( 1 − ( ζ / c ) cos ψ )) ] / ( 1 − ( ζ / c ) cos ψ ) where ξ is the velocity of fault propagation, b is the fault slip, d is the fault width, τ = t − r0/c, r0 is the distance of the observer from the initial point of faulting, c is the velocity of the seismic wave, H(τ) is the unit-step function, L is the length of the fault, and ψ the angle between r0 and the direction of fault propagation. This representation is valid for both subsonic and supersonic fault propagation. The latter case is important because Weertman (1969) has recently shown that spontaneous faulting may propagate at supersonic velocities. Because the propagation factor is always positive, the nodal planes for the radiation are the same as for the appropriate strain nucleus. Finally, it is shown by the application of this equation that the radiation from a screw dislocation segment is represented by the double-couple nucleus, not the compensated linear-vector dipole nucleus as recently suggested by Knopoff and Randall (1970).

scholarly journals Light-Emitting Metasurfaces: Simultaneous Control of Spontaneous Emission and Far-Field Radiation

Nano Letters ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 6906-6914 ◽  
Author(s):  
Sheng Liu ◽  
Aleksandr Vaskin ◽  
Sadhvikas Addamane ◽  
Benjamin Leung ◽  
Miao-Chan Tsai ◽  
...  
Keyword(s):  
Spontaneous Emission ◽  
Far Field ◽  
Light Emitting ◽  
Simultaneous Control ◽  
Field Radiation
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