scholarly journals Radiative transfer and multiple scattering of diffuse ultrasound in polycrystalline media

1994 ◽  
Vol 96 (6) ◽  
pp. 3675-3683 ◽  
Author(s):  
Joseph A. Turner ◽  
Richard L. Weaver
Keyword(s):  
Radiative Transfer ◽  
Multiple Scattering ◽  
Diffuse Ultrasound

scholarly journals Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds

2017 ◽  
Vol 9 (8) ◽  
pp. 3082-3098 ◽  
Author(s):  
Chia-Pang Kuo ◽  
Ping Yang ◽  
Xianglei Huang ◽  
Daniel Feldman ◽  
Mark Flanner ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Multiple Scattering

scholarly journals Improvement of the Simulation of Cloud Longwave Scattering in Broadband Radiative Transfer Models

2018 ◽  
Vol 75 (7) ◽  
pp. 2217-2233 ◽  
Author(s):  
Guanglin Tang ◽  
Ping Yang ◽  
George W. Kattawar ◽  
Xianglei Huang ◽  
Eli J. Mlawer ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Multiple Scattering ◽  
General Circulation ◽  
General Circulation Models ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Discrete Ordinate ◽  
Wide Range ◽  
Scaling Methods ◽  
Computational Errors

Abstract Cloud longwave scattering is generally neglected in general circulation models (GCMs), but it plays a significant and highly uncertain role in the atmospheric energy budget as demonstrated in recent studies. To reduce the errors caused by neglecting cloud longwave scattering, two new radiance adjustment methods are developed that retain the computational efficiency of broadband radiative transfer simulations. In particular, two existing scaling methods and the two new adjustment methods are implemented in the Rapid Radiative Transfer Model (RRTM). The results are then compared with those based on the Discrete Ordinate Radiative Transfer model (DISORT) that explicitly accounts for multiple scattering by clouds. The two scaling methods are shown to improve the accuracy of radiative transfer simulations for optically thin clouds but not effectively for optically thick clouds. However, the adjustment methods reduce computational errors over a wide range, from optically thin to thick clouds. With the adjustment methods, the errors resulting from neglecting cloud longwave scattering are reduced to less than 2 W m−2 for the upward irradiance at the top of the atmosphere and less than 0.5 W m−2 for the surface downward irradiance. The adjustment schemes prove to be more accurate and efficient than a four-stream approximation that explicitly accounts for multiple scattering. The neglect of cloud longwave scattering results in an underestimate of the surface downward irradiance (cooling effect), but the errors are almost eliminated by the adjustment methods (warming effect).

scholarly journals Three-dimensional in-situ imaging of cracks in concrete using diffuse ultrasound

2017 ◽  
Vol 17 (2) ◽  
pp. 279-284 ◽  
Author(s):  
Yuxiang Zhang ◽  
Eric Larose ◽  
Ludovic Moreau ◽  
Grégoire d’Ozouville
Keyword(s):  
Wind Tunnel ◽  
Multiple Scattering ◽  
Structural Changes ◽  
Imaging Technique ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Thick Wall ◽  
Pressure Changes ◽  
Diffuse Ultrasound

Locadiff, an innovative imaging technique based on diffuse waves, has recently been developed in order to image mechanical changes in heterogeneous, geological, or man-made materials. This manuscript reports the on-site application of Locadiff to locate several pre-existing cracks on an aeronautical wind tunnel made of pre-stressed concrete. Using 32 transducers working at ultrasonic frequencies (80–220 kHz) where multiple scattering occurs, we monitor during 15 min an area of 2.5 m×2.5 m of a 35-cm-thick wall. With the wind tunnel in its routine operation, structural changes around the cracks are detected, thanks to their closing or opening due to slight pressure changes. By mapping the density of such microstructure changes in the bulk of the material, locating three pre-existing cracks is properly performed in three dimensions.

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