Measurement and interpretation of the impulse response for backscattering by a thin spherical shell using a broad‐bandwidth source that is nearly acoustically transparent

1995 ◽  
Vol 97 (5) ◽  
pp. 2699-2708 ◽  
Author(s):  
Gregory Kaduchak ◽  
Christopher S. Kwiatkowski ◽  
Philip L. Marston
Keyword(s):  
Spherical Shell ◽  
Impulse Response ◽  
Broad Bandwidth ◽  
Thin Spherical Shell

Impulse response for backscattering by a thin spherical shell: Measurement and wave interpretation

1993 ◽  
Vol 94 (3) ◽  
pp. 1877-1877
Author(s):  
Gregory Kaduchak ◽  
Christopher S. Kwiatkowski ◽  
Philip L. Marston
Keyword(s):  
Spherical Shell ◽  
Impulse Response ◽  
Thin Spherical Shell

A fast approach for acoustic source localization on a thin spherical shell

2021 ◽  
pp. 147592172110419
Author(s):  
Zixian Zhou ◽  
Zhiwen Cui ◽  
Tribikram Kundu
Keyword(s):  
Velocity Profile ◽  
Spherical Shell ◽  
Source Localization ◽  
Pressure Vessels ◽  
Solution Technique ◽  
Acoustic Source ◽  
Spherical Shells ◽  
Fast Approach ◽  
Acoustic Source Localization ◽  
Thin Spherical Shell

Thin spherical shell structures are wildly used as pressure vessels in the industry because of their property of having equal in-plane normal stresses in all directions. Since very large pressure difference between the inside and outside of the wall exists, any formation of defects in the pressure vessel wall has a huge safety risk. Therefore, it is necessary to quickly locate the area where the defect maybe located in the early stage of defect formation and make repair on time. The conventional acoustic source localization techniques for spherical shells require either direction-dependent velocity profile knowledge or a large number of sensors to form an array. In this study, we propose a fast approach for acoustic source localization on thin isotropic and anisotropic spherical shells. A solution technique based on the time difference of arrival on a thin spherical shell without the prior knowledge of direction-dependent velocity profile is provided. With the help of “L”-shaped sensor clusters, only 6 sensors are required to quickly predict the acoustic source location for anisotropic spherical shells. For isotropic spherical shells, only 4 sensors are required. Simulation and experimental results show that this technique works well for both isotropic and anisotropic spherical shells.

scholarly journals Magnetic Helicity and the Solar Dynamo

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 811
Author(s):  
John V. Shebalin
Keyword(s):  
Statistical Mechanics ◽  
Spherical Shell ◽  
Turbulent Energy ◽  
Self Organization ◽  
Magnetic Helicity ◽  
Mhd Turbulence ◽  
Dynamo Action ◽  
Inherent Property ◽  
Thin Spherical Shell ◽  
Macroscopic Parameters

Solar magnetism is believed to originate through dynamo action in the tachocline. Statistical mechanics, in turn, tells us that dynamo action is an inherent property of magnetohydrodynamic (MHD) turbulence, depending essentially on magnetic helicity. Here, we model the tachocline as a rotating, thin spherical shell containing MHD turbulence. Using this model, we find an expression for the entropy and from this develop the thermodynamics of MHD turbulence. This allows us to introduce the macroscopic parameters that affect magnetic self-organization and dynamo action, parameters that include magnetic helicity, as well as tachocline thickness and turbulent energy.

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