Two-dimensional zoom FFT

Stork, R.; Hoyer, Elmer A.

doi:10.1109/icassp.1978.1170462

Cited by 1 publication

(2 citation statements)

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“…It is well‐known that FFT provides identical results as DFT while avoiding unnecessary recomputing of many intermediate terms. This algorithm is also suitable for two‐dimensional signals, resulting in a double application of FFT , first in the rows and then in the columns of the data or vice versa …”

Section: Zoom Fft Algorithmsmentioning

confidence: 99%

“…This algorithm is also suitable for two-dimensional signals, resulting in a double application of FFT, first in the rows and then in the columns of the data or vice versa. [29] With the aim of using frequency analysis to measure strains in a repetitive net, the accuracy in the evaluation of the shift requires a considerable increase in the frequency resolution (Zoom). Specific algorithms take advantage of FFT while increasing the frequency resolution are still not available, and this paper presents a method to do it.…”

Section: Zoom Fft Algorithmsmentioning

confidence: 99%

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Strain measurements on compliant knitted mesh used in space antennas, by means of 2D Fourier analysis

Salvador

Marotta

Salvini

2017

Strain

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The paper presents a strain measurement technique to be applied on repetitive knitted nets. The application of the procedure is focused on large deployable reflectors used in space applications. Manufacturing of these structures involves knitting of thin metallic wires. Besides space antennas, the method herein developed is advantageous for many other types of knitted tissues such as elastic coatings, elastic bandages for medical applications, or any other woven fabric requiring a defined elastic behaviour. All of them display an almost regular repetitive pattern whose variations due to imposed loads are the core of the method. Deformation of such kind of structural elements must be analysed in two dimensions, because the knitting causes an accentuated orthotropic behaviour. Strain measurement is tricky and requires special computational techniques. Indeed, the application of standard experimental methods and indirect strain determination, through well‐established image analysis algorithm, can be totally unsuccessful or unsuitable because of the lack of continuity of these structures. The paper presents a method based on two‐dimensional Fourier analysis. Numerical examples, supported by some experimental evidences, confirm the feasibility of the technique. Furthermore, a newly proposed frequency zooming algorithm, based on fast Fourier transform, makes the computational costs of the indirect strain measurement affordable.

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Section: Zoom Fft Algorithmsmentioning

confidence: 99%

Section: Zoom Fft Algorithmsmentioning

confidence: 99%