Sound Propagation and Scattering in Nighttime Atmospheric Boundary Layers PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Sound Propagation and Scattering in Nighttime Atmospheric Boundary Layers PDF full book. Access full book title Sound Propagation and Scattering in Nighttime Atmospheric Boundary Layers by . Download full books in PDF and EPUB format.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
Get Book Here
Book Description
In this project, we developed 3D models of temperature and wind velocity fluctuations in nighttime boundary layers (NBL) and, using these models, studied sound propagation and scattering. The 3D spectra of temperature and velocity fluctuations due to internal gravity waves in moderately and very stable NBL were obtained. The 3D spectra of turbulent temperature and wind velocity fluctuations in weakly stable, intermittent NBL were modeled with the use of the von Karman spectra. Quasi-wavelet models of turbulent temperature and velocity fluctuations were developed. The developed models of internal gravity waves, turbulence, and quasi-wavelets were then used for calculations of the statistical moments of plane and spherical sound waves propagating in the atmosphere. These calculations were done for three different problems: scattering of sound, line-of-sight sound propagation, and sound propagation in a refractive, turbulent atmosphere near an impedance ground. The coherence function of a sound field propagating in NBL was measured and compared with that predicted theoretically.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
Get Book Here
Book Description
In this project, we developed 3D models of temperature and wind velocity fluctuations in nighttime boundary layers (NBL) and, using these models, studied sound propagation and scattering. The 3D spectra of temperature and velocity fluctuations due to internal gravity waves in moderately and very stable NBL were obtained. The 3D spectra of turbulent temperature and wind velocity fluctuations in weakly stable, intermittent NBL were modeled with the use of the von Karman spectra. Quasi-wavelet models of turbulent temperature and velocity fluctuations were developed. The developed models of internal gravity waves, turbulence, and quasi-wavelets were then used for calculations of the statistical moments of plane and spherical sound waves propagating in the atmosphere. These calculations were done for three different problems: scattering of sound, line-of-sight sound propagation, and sound propagation in a refractive, turbulent atmosphere near an impedance ground. The coherence function of a sound field propagating in NBL was measured and compared with that predicted theoretically.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
Get Book Here
Book Description
A stably stratified atmosphere supports propagation of internal gravity waves (IGW). These waves result in highly anisotropic fluctuations in temperature and wind velocity that are stretched in a horizontal direction. As a result, (IGW) can significantly affect propagation of sound waves in nighttime boundary layers and infrasound waves in the stratosphere. In this paper, a theory of sound propagation through, and scattering by, (IGW) is developed. First, 3D spectra of temperature and wind velocity fluctuations due to (IGW), which were recently derived in the literature for the case of large wave numbers, are generalized to account for small wave numbers. The generalized 3D spectra are then used to calculate the sound scattering cross section in an atmosphere with (IGW). The dependencies of the obtained scattering cross section on the sound frequency, scattering angle, and other parameters of the problem are qualitatively different from those for the case of sound scattering by isotropic turbulence with the von K rm n spectra of temperature and wind velocity fluctuations. Furthermore, the generalized 3D spectra are used to calculate the mean sound field and the transverse coherence function of a plane sound wave propagating through (IGW). The results obtained also significantly differ from those for the case of sound propagation through isotropic turbulence.
Author:
Publisher:
ISBN:
Category : Acoustical engineering
Languages : en
Pages : 10
Get Book Here
Book Description
Author:
Publisher:
ISBN: 9788290569650
Category :
Languages : en
Pages : 174
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
Three-dimensional models of anisotropic and inhomogeneous spectra of temperature and wind velocity fluctuations in unstable atmospheric boundary layers have been developed, modified or extended. Furthermore, theories of sound propagation through anisotropic, inhomogeneous, and intermittent atmospheric turbulence have been developed. These theories allow consideration of different geometries of sound propagation: line-of-sight sound propagation, interference of the direct and ground reflected waves, sound scattering into a refractive shadow zone, and waveguide sound propagation. Using the spectra developed or adopted from the literature, it was shown that anisotropy, inhomogeneity, and intermittency of atmospheric turbulence can significantly affect the statistical moments of a sound field for these geometries. Some of the theoretical results obtained have been verified experimentally. Two related tasks have also been accomplished. First, a new scheme of source localization in the atmosphere by means of acoustic tomography was proposed. The scheme accounts for sound refraction in the atmosphere and allows retrieval of vertical profiles of temperature and wind velocity. Secondly, it was shown that, in many cases, the effects of sound refraction on acoustic remote sensing of wind velocity and the structure parameters of temperature and velocity fluctuations are significant. Algorithms were developed to account for these effects in acoustic remote sensing of the atmosphere.
Author: Thomas Rossing
Publisher: Springer Science & Business Media
ISBN: 0387304460
Category : Science
Languages : en
Pages : 1179
Get Book Here
Book Description
This is an unparalleled modern handbook reflecting the richly interdisciplinary nature of acoustics edited by an acknowledged master in the field. The handbook reviews the most important areas of the subject, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest research and applications are incorporated throughout, including computer recognition and synthesis of speech, physiological acoustics, diagnostic imaging and therapeutic applications and acoustical oceanography. An accompanying CD-ROM contains audio and video files.
Author:
Publisher:
ISBN:
Category : Atmospheric turbulence
Languages : en
Pages : 6
Get Book Here
Book Description
Author: H. J. Sabine
Publisher:
ISBN:
Category : Earth (Planet)
Languages : en
Pages : 32
Get Book Here
Book Description
Author: Chris L. Pettit
Publisher:
ISBN:
Category : Boundary layer (Meteorology)
Languages : en
Pages : 18
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
Sound waves propagating near the ground are scattered by random fluctuations in the velocity of temperature fields. We revisit the problem of scattering of sound by turbulence using an improved von Karman-type model for the atmospheric turbulence spectrum. The new model incorporates large boundary-layer scale eddies generated by atmospheric convection, as well as smaller height-scale eddies generated by surface-layer shear. We show that velocity fluctuations- ions from the large convective eddies are typically the cause of random signal behavior for low acoustical frequencies and line-of-sight propagation. For higher frequencies and scattering angles, the shear turbulence becomes more important, with the relative importance of scattering by temperature and velocity fluctuations depending on the degree of atmospheric convection. By applying the new model to monostatic solar systems, we find that solar measurements of the temperature structure parameter can be systematically contaminated by the velocity structure parameter in strong wind conditions. We also discuss how the new model can be used to determine appropriate baselines for direction-finding arrays when there is significant degradation of signal coherence caused by turbulence.
