A Fourier transform solution for the acoustic radiation from a source near an elastic cylinder

1991 ◽  
Vol 89 (6) ◽  
pp. 2774-2785 ◽  
Author(s):  
John L. Butler ◽  
David T. Porter
Keyword(s):  
Fourier Transform ◽  
Acoustic Radiation ◽  
Elastic Cylinder

scholarly journals Transient vibration and acoustic radiation of steering engines

2018 ◽  
Vol 37 (2) ◽  
pp. 341-354 ◽  
Author(s):  
Changgang Lin ◽  
Mingsong Zou ◽  
Huifeng Jiao ◽  
Peng Liu
Keyword(s):  
Cylindrical Shell ◽  
Fourier Transform ◽  
Acoustic Radiation ◽  
Underwater Vehicle ◽  
Processing Method ◽  
Short Time Fourier Transform ◽  
Transient Vibration ◽  
Engine Room ◽  
Signal Processing Method ◽  
Short Time

This paper mainly focuses on the remarkable transient vibration and underwater acoustic radiation when the underwater vehicle changes direction or depth, and a short time Fourier transform signal processing method to evaluate transient vibration and acoustic radiation of steering engine is provided in this paper. Based on the vibration test of the 1:1 experimental scaffold of the steering engine for an underwater vehicle, the transient maximum excitation forces acting at the contact points between steering engine and experimental scaffold are calculated indirectly by the least square method of load identification in frequency domain and the short time Fourier transform signal processing method. The accuracy and feasibility of results are verified. In addition, taking excitation forces as an approximate input, the numerical solution of transient acoustic radiation for a cylindrical shell with ribs of the steering engine room, based on elastic shell theory and fluid–structure interaction theory, is presented. In the simulation, the steering engine room of the underwater vehicle is simplified into a cylindrical shell with two simply supported tips, because a cylindrical shell with ribs is the basic structure-borne used in underwater vehicles. The results show that transient acoustic radiation of the tested steering engine is higher than allowable value, while the evaluation results of another electric steering engine without retarder are suitable.

The acoustic radiation from a semisubmerged elastic cylinder

1988 ◽  
Vol 84 (S1) ◽  
pp. S58-S58 ◽  
Author(s):  
François Jouaillec ◽  
Guillaume Jacquart
Keyword(s):  
Acoustic Radiation ◽  
Elastic Cylinder

Acoustic radiation from thin rods in water

1986 ◽  
Vol 64 (6) ◽  
pp. 671-676 ◽  
Author(s):  
B. J. Jarosz ◽  
R. L. Clarke
Keyword(s):  
Stainless Steel ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Pressure Distribution ◽  
Surface Waves ◽  
Longitudinal Wave ◽  
Acoustic Radiation ◽  
Stoneley Wave ◽  
Fast Fourier Transform Analysis ◽  
Spatial Frequencies

The ultrasound pressure distribution produced by end-excited stainless-steel rods immersed in water has been investigated. Rod diameters of 0.238 and 0.319 cm were tested at frequencies between 1.0 and 3.5 MHz. Immersion depths up to 10 cm were studied. Semiperiodic patterns were observed along the rods, with repetition lengths of 0.6 and 1.1 cm. Fast Fourier-transform analysis of the patterns showed the presence of three spatial frequencies interpreted to be the lowest mode longitudinal wave, Rayleigh-type surface waves, and the Stoneley wave propagating in the liquid.

scholarly journals Acoustic radiation force on an elastic cylinder in a Gaussian beam near an impedance boundary

Wave Motion ◽  
2020 ◽  
Vol 93 ◽  
pp. 102478
Author(s):  
Yupei Qiao ◽  
Haibin Wang ◽  
Xiaozhou Liu ◽  
Xiaofeng Zhang
Keyword(s):  
Gaussian Beam ◽  
Acoustic Radiation ◽  
Radiation Force ◽  
Elastic Cylinder ◽  
Acoustic Radiation Force ◽  
Impedance Boundary

Comparison of Calculated and Recorded Electron Energy-Loss Spectra of Aluminium and Carbon

1990 ◽  
Vol 48 (2) ◽  
pp. 64-65
Author(s):  
L. Reimer ◽  
R. Oelgeklaus
Keyword(s):  
Fourier Transform ◽  
Energy Loss ◽  
Electron Energy ◽  
Rotational Symmetry ◽  
Mean Free Path ◽  
Single Scattering ◽  
Specimen Thickness ◽  
Two Dimensional ◽  
Image Position ◽  
Electron Energy Loss

Quantitative electron energy-loss spectroscopy (EELS) needs a correction for the limited collection aperture α and a deconvolution of recorded spectra for eliminating the influence of multiple inelastic scattering. Reversely, it is of interest to calculate the influence of multiple scattering on EELS. The distribution f(w,θ,z) of scattered electrons as a function of energy loss w, scattering angle θ and reduced specimen thickness z=t/Λ (Λ=total mean-free-path) can either be recorded by angular-resolved EELS or calculated by a convolution of a normalized single-scattering function ϕ(w,θ). For rotational symmetry in angle (amorphous or polycrystalline specimens) this can be realised by the following sequence of operations :(1)where the two-dimensional distribution in angle is reduced to a one-dimensional function by a projection P, T is a two-dimensional Fourier transform in angle θ and energy loss w and the exponent -1 indicates a deprojection and inverse Fourier transform, respectively.

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