scholarly journals Acoustic Radiation in the Near‐ and Farfield of an Annular Ring Using Impulse Response and Fast Fourier Transform Techniques

1973 ◽  
Vol 53 (1) ◽  
pp. 374-374
Author(s):  
P. R. Stepanishen
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Impulse Response ◽  
Acoustic Radiation ◽  
Annular Ring

An Efficient Iterative Algorithm for Accurately Calculating Impulse Response Functions in Modal Testing

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
J. M. Liu ◽  
W. D. Zhu ◽  
Q. H. Lu ◽  
G. X. Ren
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Iterative Algorithm ◽  
Impulse Response ◽  
Mimo Systems ◽  
Spectral Lines ◽  
Modal Testing ◽  
Impulse Response Functions ◽  
Response Functions ◽  
Modal Parameter

Impulse response functions (IRFs) and frequency response functions (FRFs) are bases for modal parameter identification of single-input, single-output (SISO) and multiple-input, multiple-out (MIMO) systems, and the two functions can be transformed from each other using the fast Fourier transform and the inverse fast Fourier transform. An efficient iterative algorithm is developed in this work to directly and accurately calculate the IRFs of SISO and MIMO systems in the time domain using relatively short input and output data series. The iterative algorithm can avoid the time-consuming inversion of a large matrix in the conventional least-square method for calculating an IRF, greatly reducing the computation time. In addition, a fitting index and an error energy decreasing coefficient are introduced to evaluate the accuracy in calculating an IRF and to provide the termination criterion for the iterative algorithm. A new coherence function is also introduced to evaluate the accuracy of calculated IRFs and FRFs at different spectral lines. Two examples are given to illustrate the effectiveness and efficiency of the methodology.

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.

Piezoelectric power harvesting from chirps and mating swiftlets attraction sound

2015 ◽  
Vol 12 (4) ◽  
pp. 407-412
Author(s):  
Azrul Mahfurdz ◽  
Sunardi
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Impulse Response ◽  
Sampling Rate ◽  
Voltage Measurement ◽  
Power Harvesting ◽  
Higher Power ◽  
Piezoelectric Disk ◽  
Different Levels ◽  
Excel Format

The voltage measurement from piezoelectric disk (PZT) transducer is proposed in this paper. The attraction sound that has been used in the swiftlet farming industries was emitted at three different levels. The PZT was placed inside and outside the speaker to identify maximum power to produced high impulse voltage. The swiftlets sound was recorded using Avisoft software and analysed in Matlab. The sound was dividing into seven frames and it spectrum was plotted using Fast Fourier Transform (FFT) function to acquire the magnitude and frequency information. A Strip chart used to log and graph values acquired from PZT for 100 Hz sampling rate. The impulse response for each sample was saving in excel format and analysed in Matlab software. The finding showed, the voltage acquire from different type of swiftlets sound is significant different. In addition, the voltage generated from two PZT location also showed significant different. The reason can be highlight here is voltage generated by PZT is depending on the power of sound transmitted. The higher power sound transmitted the higher voltage generated from PZT.

GDL power extraction using fast Fourier transform

1974 ◽  
Author(s):  
D. PHELPS ◽  
J. BAUMGARDNER ◽  
G. CANAVAN
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Power Extraction
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