Research

12 pages, 2143 KiB

Open AccessArticle

All Acoustical Excitation of Spin Waves in High Overtone Bulk Acoustic Resonator

by Sergey Alekseev, Natalia Polzikova and Valery Luzanov

Acoustics 2023, 5(1), 268-279; https://doi.org/10.3390/acoustics5010016 - 01 Mar 2023

Cited by 3 | Viewed by 2260

The hybrid high overtone bulk acoustic wave resonators (HBARs) consisting of a piezoelectric film transducers and gallium gadolinium garnet substrates with yttrium iron garnet films (YIG-GGG-YIG) are used for experimental excitation and detection of acoustically driven spin waves (ADSWs). Two types of HBAR [...] Read more.

The hybrid high overtone bulk acoustic wave resonators (HBARs) consisting of a piezoelectric film transducers and gallium gadolinium garnet substrates with yttrium iron garnet films (YIG-GGG-YIG) are used for experimental excitation and detection of acoustically driven spin waves (ADSWs). Two types of HBAR transducers made of Al-ZnO-Al films (differed through the electrodes’ geometry) were deposited onto YIG-GGG-YIG trilayers with different YIG film thicknesses and doping levels and served for excitation of multimode HBAR at gigahertz frequencies. ADSWs were detected by measuring the shifts of resonant HBAR modes in a tangential external magnetic field when the conditions for magnetoelastic resonance (MER) were satisfied. It was shown that the design of the transducer with a continuous bottom electrode provides all acoustical excitation of spin waves (pure ADSWs), suppressing the additional inductive magnetic dynamics excitation due to the electrodes’ geometry. The theoretical study of the HBAR spectrum in a magnetic field showed that the resonance harmonics in the MER region can either almost continuously transfer from one to another, or decay and form an evident magnetoelastic gap. In this case, the shift of resonant frequencies can achieve several intermodal distances. The results obtained are important for applications of HBAR-based devices in spintronics and magnonics. Full article

(This article belongs to the Special Issue Resonators in Acoustics)

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12 pages, 1599 KiB

Open AccessArticle

Resonant Metasurfaces with a Tangential Impedance

by Nikolay Kanev

Acoustics 2022, 4(4), 903-914; https://doi.org/10.3390/acoustics4040055 - 21 Oct 2022

Cited by 3 | Viewed by 1903

Abstract

Metasurfaces formed by monopole and dipole resonators are studied theoretically. The monopole resonators are Helmholtz resonators or membranes vibrating on the first eigenfrequency; the dipole ones are spheres on springs or membranes vibrating on the second eigenfrequency. It is shown that acoustic properties [...] Read more.

Metasurfaces formed by monopole and dipole resonators are studied theoretically. The monopole resonators are Helmholtz resonators or membranes vibrating on the first eigenfrequency; the dipole ones are spheres on springs or membranes vibrating on the second eigenfrequency. It is shown that acoustic properties of the metasurface formed by the built-in monopole resonators can be described by an equivalent impedance, which characterizes a normal forcing to the surface, whereas this impedance is not suitable for the metasurface formed by the dipole resonators, because motion of the metasurface is excited by a forcing tangential to the surface. For such boundaries, a new characteristic named “tangential impedance” is proposed. This is a ratio of the second derivative of the sound pressure along a coordinate tangential to the boundary to the normal velocity of the boundary. The dipole metasurface can be described by the equivalent tangential impedance. Reflection and absorption coefficients of the surface with the tangential impedance are found for a harmonic plane wave in dependance of an incidence angle. It is found that the angular dependences of the coefficients are very different for the monopole and dipole metasurfaces. Full article

(This article belongs to the Special Issue Resonators in Acoustics)

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10 pages, 2284 KiB

Open AccessArticle

Evaluation of the Oscillation Velocity in the Neck of the Helmholtz Resonator in Nonlinear Regimes

by Alexandr Komkin, Aleksei Bykov and Olga Saulkina

Acoustics 2022, 4(3), 564-573; https://doi.org/10.3390/acoustics4030035 - 19 Jul 2022

Cited by 4 | Viewed by 2211

Abstract

Methods for measuring the acoustic characteristics of orifices have been reviewed. Comparison of three methods for evaluating of oscillation velocity in the neck of the Helmholtz resonator are presented. The first method is measurements in an impedance tube with the two-microphone method, the [...] Read more.

Methods for measuring the acoustic characteristics of orifices have been reviewed. Comparison of three methods for evaluating of oscillation velocity in the neck of the Helmholtz resonator are presented. The first method is measurements in an impedance tube with the two-microphone method, the second is based on measuring the sound pressure in the resonator chamber, and the third is based on direct measurements of bias flow with a Pitot tube. The results of measuring the oscillation velocity in the neck of the Helmholtz resonator are presented, and show that these methods are in good agreement only within linear acoustics, but they lead to different results in nonlinear regimes characterized by high sound pressure levels. Full article

(This article belongs to the Special Issue Resonators in Acoustics)

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10 pages, 1794 KiB

Open AccessArticle

The Dipole Resonator and Dipole Waveguide Insulator in Dense Liquid Medium

by Mikhail Mironov

Acoustics 2022, 4(2), 469-478; https://doi.org/10.3390/acoustics4020029 - 22 May 2022

Cited by 3 | Viewed by 2650

Abstract

In this paper, the propagation of sound in an acoustically narrow waveguide, the wall of which is lined with identical dipole resonators and masses on springs, is theoretically considered. It is shown that, in the frequency range above the resonant frequency of the [...] Read more.

In this paper, the propagation of sound in an acoustically narrow waveguide, the wall of which is lined with identical dipole resonators and masses on springs, is theoretically considered. It is shown that, in the frequency range above the resonant frequency of the resonators, sound waves exponentially attenuate, and the waveguide is locked. The width of this range depends on two parameters—the ratio of the cross-sectional areas of the resonators and the waveguide and the ratio of the mass of the resonator to the mass of the medium displaced by it. As the resonator mass decreases, the locking band width expands and may become infinite. Full article

(This article belongs to the Special Issue Resonators in Acoustics)

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12 pages, 2978 KiB

Open AccessArticle

On the Influence of Certain Geometric Characteristics of the Resonator on the Impedance Determined by the Dean’s Method

by Vadim Palchikovskiy, Igor Khramtsov and Oleg Kustov

Acoustics 2022, 4(2), 382-393; https://doi.org/10.3390/acoustics4020023 - 11 Apr 2022

Cited by 1 | Viewed by 2521

Abstract

This article considers the influence of the orifice arrangement in a cover of a cylindrical resonator on the impedance determined by the Dean’s method. A resonator with a small height and a low perforation degree is studied. This geometry provides different non-uniformity of [...] Read more.

This article considers the influence of the orifice arrangement in a cover of a cylindrical resonator on the impedance determined by the Dean’s method. A resonator with a small height and a low perforation degree is studied. This geometry provides different non-uniformity of the sound field at the resonator backing depending on the orifice arrangement in the resonator cover, while the number of orifices does not change. It is shown that, with different orifice arrangements, the impedance values determined by Dean’s method at high frequencies (3000 Hz and more) differ greatly. The authors propose the modification of Dean’s formula by using the amplitude coefficient of the zeroth order mode instead of the acoustic pressure at the resonator backing. The computations performed demonstrate that, in this case, the impedance does not depend on the orifice arrangement in the resonator cover. The computations consist of three stages: numerical simulation of the plane wave incidence onto the resonator (simulating a full-scale experiment); carrying out a modal analysis of the sound field at the resonator backing to extract the zeroth order mode; and determination of the resonator impedance according to the modified Dean’s formula. Full article

(This article belongs to the Special Issue Resonators in Acoustics)

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16 pages, 864 KiB

Open AccessArticle

Dual-Axis MEMS Resonant Scanner Using 128^∘Y Lithium Niobate Thin-Film

by Yaoqing Lu, Kangfu Liu and Tao Wu

Acoustics 2022, 4(2), 313-328; https://doi.org/10.3390/acoustics4020019 - 01 Apr 2022

Cited by 4 | Viewed by 3809

Abstract

The micro-electro-mechanical systems (MEMS) resonant scanners are in great demand for numerous light scanning applications. Recently, the development of LiDAR in micro-robotics and mobile devices has led to the requirement of ultra-small systems with low driving voltage, low power, compact size and high [...] Read more.

The micro-electro-mechanical systems (MEMS) resonant scanners are in great demand for numerous light scanning applications. Recently, the development of LiDAR in micro-robotics and mobile devices has led to the requirement of ultra-small systems with low driving voltage, low power, compact size and high performance. We have first proposed the dual-axis MEMS scanner using the lithium niobate (LN) thin-film platform, which is expected to fulfill the requirement. This paper describes the actuation principle and scanner structure, meanwhile develops the analytical model for the scanner. The analytical model is later validated by the finite element analysis. The performance of the proposed scanner is improved with the optimization of the orientation of LN and layer thickness. The proposed scanner achieves the

θ_{opt} \cdot D \cdot f

up to 937.8

^{\circ} \cdot mm \cdot kHz

in simulation. The simulated optical angle in the x-axis and y-axis are 50

^{\circ}

and 42

^{\circ}

at 1 V, corresponding to resonant frequencies of 79.9 kHz and 558.2 kHz, respectively. With the superior performance of large deflection, high scanning frequency, high figure of merit and low voltage, the proposed MEMS scanner is a promising candidate for fast scanner applications (e.g., wavelength-selective switches and submicron biomedical system), especially the application of LiDAR in mobile devices or micro-robotics. Full article

(This article belongs to the Special Issue Resonators in Acoustics)

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12 pages, 26151 KiB

Open AccessArticle

Design of Digital Constrained Linear Least-Squares Multiple-Resonator-Based Harmonic Filtering

by Miodrag D. Kušljević and Vladimir V. Vujičić

Acoustics 2022, 4(1), 111-122; https://doi.org/10.3390/acoustics4010008 - 01 Feb 2022

Cited by 2 | Viewed by 2525

Abstract

Although voiced speech signals are physical signals which are approximately harmonic and electric power signals are true harmonic, the algorithms used for harmonic analysis in electric power systems can be successfully used in speech processing, including in speech enhancement, noise reduction, speaker recognition, [...] Read more.

Although voiced speech signals are physical signals which are approximately harmonic and electric power signals are true harmonic, the algorithms used for harmonic analysis in electric power systems can be successfully used in speech processing, including in speech enhancement, noise reduction, speaker recognition, and hearing aids. The discrete Fourier transform (DFT), which has been widely used as a phasor estimator due to its simplicity, has led to the development of new DFT-based algorithms because of its poor performance under dynamic conditions. The multiple-resonator (MR) filter structure proposed in previous papers has proven to be a suitable approach to dynamic harmonic analysis. In this article, optimized postprocessing compensation filters are applied to obtain frequency responses of the transfer functions convenient for fast measurements in dynamic conditions. An optimization design method based on the constrained linear least-squares (CLLS) is applied. This way, both the flatness in the passband and the equiripple attenuation in the stopband are satisfied simultaneously, and the latency is reduced. Full article

(This article belongs to the Special Issue Resonators in Acoustics)

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23 pages, 41648 KiB

Open AccessArticle

Sound Enhancement of Orthotropic Sound Radiation Plates Using Line Loads and Considering Resonance Characteristics

by Ahmad Nayan and Tai Yan Kam

Acoustics 2021, 3(4), 642-664; https://doi.org/10.3390/acoustics3040041 - 18 Oct 2021

Cited by 2 | Viewed by 2985

Abstract

A new vibro-acoustic method is presented to analyze the sound radiation behavior of orthotropic panel-form sound radiators using strip-type exciters to exert line loads to the panels for sound radiation. The simple first-order shear deformation theory together with the Ritz method is used [...] Read more.

A new vibro-acoustic method is presented to analyze the sound radiation behavior of orthotropic panel-form sound radiators using strip-type exciters to exert line loads to the panels for sound radiation. The simple first-order shear deformation theory together with the Ritz method is used to formulate the proposed method that makes the vibro-acoustic analysis of elastically restrained stiffened orthotropic plates more computationally efficient than the methods formulated on the basis of the other shear deformation theories. An elastically restrained orthotropic plate consisting of two parallel strip-type exciters was tested to measure the experimental sound pressure level curve for validating the effectiveness and accuracy of the proposed method. The resonance characteristics (natural frequency and mode shape) detrimental to sound radiation are identified in the vibro-acoustic analysis of the orthotropic plate. For any orthotropic sound radiation plate, based on the detrimental mode shapes, a practical procedure is presented to design the line load locations on the plate to suppress the major sound pressure level dips for enhancing the smoothness of the plate sound pressure level curve. For illustration, the sound radiation enhancement of orthotropic plates with different fiber orientations for aspect ratios equal to 3, 2, and 1 subjected to one or two line loads is conducted using the proposed procedure. The results for the cases with two line loads perpendicular to the fiber direction and located at the nodal lines of the major detrimental mode shape may find applications in designing orthotropic panel-form speakers with relatively smooth sound pressure level curves. Full article

(This article belongs to the Special Issue Resonators in Acoustics)

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12 pages, 4107 KiB

Open AccessArticle

Design, Manufacturing, and Acoustical Analysis of a Helmholtz Resonator-Based Metamaterial Plate

by Sourabh Dogra and Arpan Gupta

Acoustics 2021, 3(4), 630-641; https://doi.org/10.3390/acoustics3040040 - 16 Oct 2021

Cited by 14 | Viewed by 4449

Abstract

Acoustic metamaterials are materials artificially engineered to control sound waves, which is not possible with conventional materials. We have proposed a design of an acoustic metamaterial plate with inbuilt Helmholtz resonators. The plate is made of Polylactic acid (PLA) which is fabricated using [...] Read more.

Acoustic metamaterials are materials artificially engineered to control sound waves, which is not possible with conventional materials. We have proposed a design of an acoustic metamaterial plate with inbuilt Helmholtz resonators. The plate is made of Polylactic acid (PLA) which is fabricated using an additive manufacturing technique. It consists of Helmholtz resonator-shaped cavities of different sizes. In this paper, we have analyzed the acoustic properties of the Helmholtz resonators-based metamaterial plate experimentally as well as numerically. The experimental results are in good agreement with the numerical results. These types of 3D-printed metamaterial plates can find their application where high sound transmission loss is required to create a quieter ambience. There is an additional advantage of being lightweight because of the Helmholtz resonator-shaped cavities built inside the plate. Thus, these types of metamaterial plates can find their application in the design sector requiring lighter materials with high sound transmission loss. Full article

(This article belongs to the Special Issue Resonators in Acoustics)

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21 pages, 3590 KiB

Open AccessArticle

An Experimental and Numerical Study on the Effect of Spacing between Two Helmholtz Resonators

by Abhishek Gautam, Alper Celik and Mahdi Azarpeyvand

Acoustics 2021, 3(1), 97-117; https://doi.org/10.3390/acoustics3010009 - 15 Feb 2021

Cited by 11 | Viewed by 5530

Abstract

This study investigates the acoustic performance of a system of two Helmholtz resonators experimentally and numerically. The distance between the Helmholtz resonators was varied to assess its effect on the acoustic performance of the system quantitatively. Experiments were performed using an impedance tube [...] Read more.

This study investigates the acoustic performance of a system of two Helmholtz resonators experimentally and numerically. The distance between the Helmholtz resonators was varied to assess its effect on the acoustic performance of the system quantitatively. Experiments were performed using an impedance tube with two instrumented Helmholtz resonators and several microphones along the impedance tube. The relation between the noise attenuation performance of the system and the distance between two resonators is presented in terms of the transmission loss, transmission coefficient, and change in the sound pressure level along the tube. The underlying mechanisms of the spacing effect are further elaborated by studying pressure and the particle velocity fields in the resonators obtained through finite element analysis. The results showed that there might exist an optimum resonators spacing for achieving maximum transmission loss. However, the maximum transmission loss is not accompanied by the broadest bandwidth of attenuation. The pressure field and the sound pressure level spectra of the pressure field inside the resonators showed that the maximum transmission loss is achieved when the resonators are spaced half wavelength of the associated resonance frequency wavelength and resonate in-phase. To achieve sound attenuation over a broad frequency bandwidth, a resonator spacing of a quarter of the wavelength is required, in which case the two resonators operate out-of-phase. Full article

(This article belongs to the Special Issue Resonators in Acoustics)

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