A planar array for the generation of evanescent waves

Trivett, D. H.; Luker, L. D.; Petrie, Sarah; Buren, A. L. Van; Blue, Joseph E.

doi:10.1121/1.399046

Cited by 13 publications

(6 citation statements)

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“…The results presented here, which demonstrate that an optimal value of the incident wave decay rate can be identified with incidence near the Rayleigh angle, may prove useful for non-contact excitation in applications such as nondestructive testing 1,2,[4][5][6] and medical ultrasound imaging. 7,8 Moreover, these waveforms may be generated in practice by sound field reproduction techniques with phased arrays of sources, 29,[37][38][39] or by other approaches, 27,28,31,40 though the distortion of the profile over nonzero standoff distances would have to be carefully controlled in such an implementation (see also the Appendix). The generation of bounded inhomogeneous waves of the type considered in this work, in particular, was investigated by Declercq and Leroy, 26 and it was noted that a reasonable approximation may be achievable in the near field.…”

Section: Discussionmentioning

confidence: 99%

Bounded inhomogeneous wave profiles for increased surface wave excitation efficiency at fluid–solid interfaces

Woods

Bolton

Rhoads

2017

The Journal of the Acoustical Society of America

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Though the ultrasonic excitation of surface waves in solids is generally realized through the use of a contact transducer, remote excitation would enable standoff testing in applications such as the nondestructive evaluation of structures. With respect to the optimal incident wave profile, bounded inhomogeneous waves, which include an exponentially decaying term, have been shown to improve the surface wave excitation efficiency as compared to Gaussian and square waves. The purpose of this work is to investigate the effect of varying the incident wave spatial decay rate, as applied to both lossless fluid-solid interfaces and to solids with viscoelastic losses included. The Fourier method is used to decompose the incident profile and subsequently compute the reflected wave profile. It is shown that inhomogeneous plane wave theory predicts, to a close approximation, the location of the minimum in the local reflection coefficient with respect to the decay rate for bounded incident waves. Moreover, plane wave theory gives a reasonable indication of the decay rate that maximizes the surface wave excitation efficiency.

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Section: Discussionmentioning

confidence: 99%

Bounded inhomogeneous wave profiles for increased surface wave excitation efficiency at fluid–solid interfaces

Woods

Bolton

Rhoads

2017

The Journal of the Acoustical Society of America

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“…In Ref. [7], generation of an evanescent wave by using a piezoelectric array consisting of a sheet of polyvinylidene fluoride with electrode stripes is reported. In Ref.…”

Section: Introductionmentioning

confidence: 99%

Evanescentwave reproduction using linear array of loudspeakers

Itou

Furuya

Hori

2011

2011 IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA)

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An acoustic evanescent wave reproduction method is presented. Evanescent waves have faster distance attenuation. In most sound field reproduction approaches, the evanescent wave is a spatial aliasing component and is an undesirable wave field for reproducing a pure plane wave. However, because of its faster distance attenuation property, it does not affect these approaches. In this work, we attempt to reproduce only the evanescent wave. If only the evanescent wave is reproduced, it can be applied for a local area sound reproduction system that can localize a sound field around one specific location. The evanescent wave reproduction system is constructed by using a linear loudspeaker array and digital filters. Computer simulation results showed that our method achieves faster distance attenuation than a simple sound source.Index Terms-evanescent wave, fast distance attenuation, local area sound reproduction, linear loudspeaker array, digital filter

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“…5) The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing distance from the surface of the vibrating plate. [6][7][8] Therefore, it is possible to perform data communication without leaking acoustic data. Additionally, the existing acoustic communication system for mobile devices transmits data at a low speed because the frequency band is limited to near the maximum auditory frequency of 18 kHz to prevent the radiation of sound that may be unpleasant for people.…”

Section: Introductionmentioning

confidence: 99%

Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

Fujii

Wakatsuki

Mizutani

2015

Jpn. J. Appl. Phys.

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A method of suppressing sound radiation to the far field of a near-field acoustic communication system using an evanescent sound field is proposed. The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing a distance from the surface of the vibrating plate. However, a discontinuity of the sound field exists at the edge of the finite vibrating plate in practice, which broadens the wavenumber spectrum. A sound wave radiates over the evanescent sound field because of broadening of the wavenumber spectrum. Therefore, we calculated the optimum distribution of the particle velocity on the vibrating plate to reduce the broadening of the wavenumber spectrum. We focused on a window function that is utilized in the field of signal analysis for reducing the broadening of the frequency spectrum. The optimization calculation is necessary for the design of window function suitable for suppressing sound radiation and securing a spatial area for data communication. In addition, a wide frequency bandwidth is required to increase the data transmission speed. Therefore, we investigated a suitable method for calculating the sound pressure level at the far field to confirm the variation of the distribution of sound pressure level determined on the basis of the window shape and frequency. The distribution of the sound pressure level at a finite distance was in good agreement with that obtained at an infinite far field under the condition generating the evanescent sound field. Consequently, the window function was optimized by the method used to calculate the distribution of the sound pressure level at an infinite far field using the wavenumber spectrum on the vibrating plate. According to the result of comparing the distributions of the 1/40 Japanese Journal of Applied Physics REGULAR PAPER sound pressure level in the cases with and without the window function, it was confirmed that the area whose sound pressure level was reduced from the maximum level to-50 dB was extended. Additionally, we designed a sound insulator so as to realize a similar distribution of the particle velocity to that obtained using the optimized window function. Sound radiation was suppressed using a sound insulator put above the vibrating surface in the simulation using the three-dimensional finite element method. On the basis of this finding, it was suggested that near-field acoustic communication which suppressed sound radiation can be realized by applying the optimized window function to the particle velocity field.

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A planar array for the generation of evanescent waves

Cited by 13 publications

References 0 publications

Bounded inhomogeneous wave profiles for increased surface wave excitation efficiency at fluid–solid interfaces

Bounded inhomogeneous wave profiles for increased surface wave excitation efficiency at fluid–solid interfaces

Evanescentwave reproduction using linear array of loudspeakers

Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

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