Maksimov O. «Features of Rayleigh Scattering by a Particle Near an Interface» Acoustical Physics, 70, № 1, с. 1-8 (2024)

Features of Rayleigh scattering by a solid particle at a small distance compared to the wavelength from an impenetrable plane boundary are revealed. The choice of the Green’s function in the integral representation of the Helmholtz equation makes it possible to reduce integration only over the particle surface and eliminate the contribution of the interface surface. When expanding over a small wave parameter, a well-known approach is used, making it possible to represent the solution of a given order as the sum of a potential function and a component expressed in terms of lower-order approximations. The potential component is found, expressed in terms of solid irregular harmonics centered on the particle and its mirror image. The vibrational velocity of the center of a particle and the scattering amplitude are determined. In the lowest order of the wavenumber, the scattering amplitude is expressed in terms of the monopole and dipole components.

Bashkatov V.V., Ostrikov N.N. «Influence of the Nonlinear Operating Mode of Acoustic Liners at High Sound Pressure Levels on Sound Wave Propagation in a Cylindrical Duct with a Flow» Acoustical Physics, 70, № 1, с. 9-20 (2024)

The problem of sound propagation in a cylindrical duct with a uniform flow is considered with nonlinear impedance boundary conditions resulting from the dependence of the impedance of acoustic liners on the sound pressure level. An iterative procedure for solving this problem has been constructed, in which sound propagation is described by an asymptotic solution to the problem of the propagation of sound modes in a cylindrical duct with a uniform flow with a smoothly non-uniform impedance of the walls in the axial direction, and the nonlinear mode of operation of the liners is based on a semiempirical model of a two-layer acoustic liners. It is shown that the constructed iterative algorithm converges within the limits of applicability of the asymptotic solution and diverges beyond them. It is shown that, for the parameters with which the calculations were carried out, the nonlinear effect of the liners operation leads to an increase in sound attenuation compared to a linear solution of a similar problem, and this effect is when sound propagates along rather than against the flow.

Anosov A., Granovsky N.V., Belyaev R.V., Erofeev A.V., Sanin A.G., Mansfeld A.D. «Correlation Measurements of Thermal Acoustic Radiation Using a Sensor Array» Acoustical Physics, 70, № 1, с. 21-28 (2024)

An array consisting of three sensors was used for correlation measurements of thermal acoustic radiation. For the first time, all cross-correlation functions were obtained for each pair of sensors. The measurements were carried out at two positions of the source (a heated narrow Teflon cylinder), the distance between which was equal to half the spatial period of the cross-correlation function of adjacent sensors. The measured correlation functions were in antiphase, which corresponds to the calculated correlation functions of thermal acoustic radiation. To pass from correlation functions to temperature distribution, spatial cross-correlation functions for adjacent and the outermost sensors in the array are summed. The correlation methodology makes it possible to significantly increase the spatial resolution of the method.

Gladkov S.O. «On the Sound Speed in Multiphase Systems» Acoustical Physics, 70, № 1, с. 29-34 (2024)

The general dependence of the sound speed has been calculated c_s in a two-phase system, such as liquid+gas and gas+liquid, as a function of the concentration x of an additional phase and thermodynamic parameters of the mixture. It is shown that in limiting cases, when the concentration tends to zero or unity, formulas are obtained whose numerical values agree well with the known values for the sound speed in water and air. This formula is generalized to multicomponent systems. The found functional relationship is illustrated graphically c_s(x) for the case of a two-phase medium, and its qualitative and quantitative agreement with the results of other authors is shown demonstrated.

Dembelova T.S., Makarova D.N., Badmaev B.B. «Low-Frequency Shear Elasticity of the Homological Series of Normal Hydrocarbons» Acoustical Physics, 70, № 1, с. 35-38 (2024)

The low-frequency (74 kHz) shear elasticity of the homologous series of normal hydrocarbons (alkanes) is studied using acoustic resonance. The shear modulus and mechanical loss tangent are measured, and the relaxation frequency and effective viscosity are calculated. The dependences of these parameters on homologue viscosity are established. It is shown that the mechanical loss tangent of all studied liquids is less than 1, demonstrating that the relaxation frequency is below the experimental frequency.

Kazakov L.I. «On A Sound-Absorbing Coating in the form of a Layer of a Viscous Liquid with Bubbles» Acoustical Physics, 70, № 1, с. 39-50 (2024)

The study considers the possibility of creating a broadband sound-absorbing coating for hydroacoustic measuring tanks and chambers with inertial or soundproof walls, consisting of a layer of viscous liquid with gas bubbles. The coatings are calculated using the well-known theory of sound propagation in a liquid medium with bubbles, as well as the Kramers–Kronig integral dispersion equations. It is shown that the volumetric size distribution function of bubbles should be constant over the entire range of their sizes. A viscous liquid is designed to increase bubble damping to a value on the order of unity that is optimal for coatings by adding viscous losses in the surrounding liquid to small thermal losses. Low-frequency compensating resonators are used in coatings for soundproof walls. Several examples of calculating the acoustic characteristics of coatings are given.

Kurashkin K.V., Kirillov A.G., Gonchar A.V. «Use of Longitudinal Critically Refracted Waves to Determine Residual and Temperature Stresses in Rails» Acoustical Physics, 70, № 1, с. 51-57 (2024)

The possibility of using longitudinal critically refracted waves for acoustic strain gauging of longitudinal residual and temperature stresses in rails is studied. The influence of stress and temperature on the propagation velocity of elastic waves in rail steel is analyzed theoretically. An algorithm is presented for determining longitudinal stress in a rail by measuring the propagation time of longitudinal critically refracted waves. The operational principle is described, and the main parameters of an acoustic strain gauge device are presented, in which a differential scheme for measuring the propagation time of longitudinal critically refracted waves is implemented. Longitudinal critically refracted waves that propagate along a rail are emitted and received from the rolling surface of a rail head using contact piezoelectric transducers fixed on the polymethylmethacrylate wedges. The results of acoustomechanical and temperature tests are presented. The measurement errors are calculated. The results of determining the level of residual welding stresses in the head of a new rail are presented. The experimental results are compared with theoretical estimates of the stresses that arise in a rail under the influence of temperature, as well as with available data in the literature on residual stresses in rails.

Liu S., Li M., Zhao R. «The Sound Source Location Based on Phase Conjugation and Acoustic Superlens» Acoustical Physics, 70, № 1, с. 58-67 (2024)

In order to break through the diffraction limit of traditional sound sources, an idea of far-field super-resolution imaging based on acoustic superlens is proposed, that is, acoustic super-lens is used to transmit near-field sound field information to the far-field, and far-field super-resolution imaging is realized by combining phase conjugate algorithm. In this paper, the sound source localization effect of the two-dimensional honeycomb acoustic superlens of water/mercury material is systematically studied, and the sub-wavelength imaging with a resolution of 0.22λ is obtained by simulating the point sound source imaging through numerical simulation, and the imaging principle of the refractive index n=–1 configuration is explained by combining the imaging principle of flat lens imaging and the law of refraction. A multi-lens was designed for far-field localization of point sound sources, and sub-wavelength imaging with a resolution of 0.19λ was obtained.

Mansfeld D., Belyaev R.V., Volkov G.P., Kuzmin A.A., Sanin A.G., Shaikin A.A. «Monitoring the Internal Temperature of Active Elements of High-Power Lasers Using Ultrasonic Probing» Acoustical Physics, 70, № 1, с. 68-75 (2024)

Monitoring the internal temperature of active elements (AE) of high-power lasers is necessary for their safe operation. The article describes a method and device for monitoring the internal temperature of the AE of lasers. The measurements utilize pulsed ultrasonic (US) probing and the temperature dependence of the sound speed in the AE material. A change in the sound speed leads to a change in the phase of the ultrasonic signal passing through the object, which is recorded by the described device. The results of monitoring the AE temperature using ultrasonic probing during operation of a laser device are presented.

Raza M., Ahsan M., Wee M.F.M.R., Baqir M.A. «Investigation of Open Cloaking of Acoustic Fields via Transformation Optics» Acoustical Physics, 70, № 1, с. 76-81 (2024)

The conventional cloak has been studied in vast space while the open cloaking is explored in a few articles and there is a dire need for further investigations in this field. The open cloaks provide a way to exchange information data from the cloaked region to outside and vice versa. In this work, we have investigated the open cloaking phenomenon in acoustic fields at an audible frequency. This study will be helpful in developing a Multiphysics open cloaking platform and cloaked will enable to transfer or prohibition of the exchange of material from one region to another.

Tsysar S.A., Rosnitskiy P.B., Asfandiyarov S.A., Petrosyan S.A., Khokhlova V.A., Sapozhnikov O.A. «Phase Correction of the Channels of a Fully Populated Randomized Multielement Therapeutic Array Using the Acoustic Holography Method» Acoustical Physics, 70, № 1, с. 82-89 (2024)

The acoustic holography method was used to characterize a therapeutic focused fully populated 256-element ultrasonic transducer array. Elements of the array with the shape of equal area polygons are densely arranged in an irregular pattern on a spherically concave surface with a radius of curvature of 150 mm and a diameter of 200 mm. The array has a central frequency of 1.2 MHz and is designed to operate in water. The performance of individual array elements was studied based on the holographically reconstructed normal velocity distribution over the array surface. It was shown that with the same electrical signals applied to the elements, their acoustic responses had a phase deviation relative to the nominal values, which can be caused either by the asphericity of the array surface, or by the introduction of additional phase delays by the electrical matching network. To compensate for the detected parasitic phase shifts of the elements and restore the effective sphericity of the radiating surface, the Verasonics V-1 control system was used. The hologram measured after making the correction, as well as the shape of the focal region and acoustic pressure magnitude at the focus, separately measured by a hydrophone, showed that the proposed method reconstructed the nominal operating parameters of the array with high accuracy.

Wang Y., Chen C. «Traveling Surface Acoustic Wave Induced Removal of NSB Proteins from the Acoustic Biosensor» Acoustical Physics, 70, № 1, с. 90-104 (2024)

One challenge of current biosensors is to remove non-specifically bound (NSB). Surface acoustic wave (SAW) technology, because of its non-contact and non-marker characteristics, becomes one of the hot research fields and shows great prospects. In this paper, SAW is used to remove NSB. Firstly, the effect of the cut of the piezoelectric material on the removal force is determined based on the dispersion equation of the acoustic wave and the properties of the piezoelectric material. Secondly, the effects of channel height, excitation voltage and fluid medium temperature on the removal process are verified through theoretical calculations. The results show that the SAW force, lift force and drag force induce by the SAW can effectively remove the NSB, among which, SAW force mainly removes the nonspecifically bound from sensor surface, while the lift force and drag force mainly prevent the re-deposition of the removed NSB. Finally, the optimal region where NSB can be removed effectively by SAW is determined by comparing the SAW force and van der Waals force. When the sensing region is located in the optimal region, not only can the NSB be effectively removed, but also the performance of the sensor is guaranteed.

Aksenov S.P., Kuznetsov G.N. «Interference Invariants in Hydroacoustic Field Maxima in Deep Water» Acoustical Physics, 70, № 1, с. 105-115 (2024)

Chuprov’s interference invariant (II) well describes the properties of a sound field in shallow water. However, the question of how applicable Chuprov’s II concept is to deep water, where the patterns of sound field decay with distance are more complex has been insufficiently studied. Therefore, the authors studied the II properties in the near and far fields of acoustic illumination, as well as in the shadow zone. A new definition of the invariant was proposed and studied, and its characteristics were compared with Chuprov’s II as a function of distance, reception and emission depths, and summer or winter propagation conditions. The new invariant is called the phase-energy invariant (PEI), since orthogonal components of the phase gradient are used to describe the spatial sound energy distribution. The stability of the new invariant, its independence on different influencing factors, and its natural change with distance from zero to one are shown. It has been established that in winter conditions, at almost all distances, the PEI is equal to unity, and the II does not have stable values and varies jumpwise over a very wide range. In summer conditions, in the shadow zone, with increasing distance, the PEI increases, just like the II, from close to zero to one. In the near and far fields of acoustic illumination, the PEI is approximately equal to unity, and the II in these zones, both in summer and winter, is characterized by unlimited oscillations, caused by division by a value close to zero. It is shown that the definition of PEI is valid both in single-mode waveguides and in free unbounded space with a dispersive medium.

Bychkov P., Faranosov G.A. «Hot-Wire-Based Estimation of Pressure Fluctuations in the Near Field of a Jet in the Presence of a Coflow» Acoustical Physics, 70, № 1, с. 116-129 (2024)

It is shown that the velocity fluctuation spectra measured using a hot wire in the potential flow region of the near field of a turbulent jet with a coflow can be converted into pressure fluctuation spectra. The proposed conversion method is based on the fact that the structure of instability waves, which make a decisive contribution to jet near-field fluctuations, resembles homogeneous one-dimensional waves, which makes it possible to locally link pressure fluctuations and the fluctuations of the streamwise velocity component measured by a hot wire.

Bai Yunshan, Liu Yuanxue, Gao Guangjian, Cui Dandan, Chen Han «Estimating the Azimuth of Acoustic Emission Source in Concrete Plate-Like Structures using a Non-Contact Sensor Unit» Acoustical Physics, 70, № 1, с. 130-142 (2024)

Location of damage sources is an important aspect of structural health monitoring research. Acoustic emission (AE) technology is broadly concerned due to its potential advantages in damage monitoring and source localization. However, the traditional positioning method is based on the arrival of P wave, and the non-uniformity of concrete materials is not considered, resulting in poor accuracy at large distances. This paper describes a non-contact AE localization method using leaky Rayleigh waves via a new air-coupled MEMS microphones array unit. Compared with traditional contact detection, this method is convenient for rapid setup and monitoring in a wider range. The feasibility of the non-contact AE localization method was verified by numerical simulation and experiments. Azimuth (direction of arrival) of AE source is a key source parameter for damage location. The research shows that this method can determine the azimuth of AE source at different positions, the results are close to the actual coordinates. Non-contact monitoring method proposed in this paper is the basis for further research on the failure prediction of concrete plate-like structures such as tunnel lining and bridge deck.

Zhang E.L., Peng Z.L., Li Z.J., Lin Y.B., Zhuo J.M. «Four-Channel Active Noise Control Modeling and Offline Simulation for Electric Bus Sound Quality Based on Two FxLMS Algorithms» Acoustical Physics, 70, № 1, с. 143-152 (2024)

Aiming at the consensus problem of slow convergence for the active noise control (ANC) model based on standard FxLMS algorithm that leads to performance degradation, this paper takes the error signal and its variation as the inputs of fuzzy logic control, and proposes an improved FxLMS algorithm by fuzzy control mechanism with two-input-two-output TSK fuzzy rules (TSK-FxLMS); In addition, the four-channel ANC models based on standard FxLMS and TSK-FxLMS are constructed using the noise signals from four measuring points inside an electric bus under uniform and variable speed conditions, respectively. Ultimately, the offline simulation and acoustic parameter calculation results indicate that the A-weighted sound pressure level (ASPL) and loudness of the two FxLMS models within the low and middle frequencies are significantly reduced, whereas the TSK-FxLMS model has faster convergence rate, higher average reduction percentage of ASPL and loudness, which proves that the established four-channel TSK-FxLMS model has a better sound quality improvement effect than the standard FxLMS.

Bakushinsky B., Leonov A.S. «Modeling the Solution of the Acoustic Inverse Problem of Scattering for a Three-Dimensional Nonstationary Medium» Acoustical Physics, 70, № 1, с. 153-164 (2024)

The inverse problem of acoustic sounding of a three-dimensional nonstationary medium is considered, based on the Cauchy problem for the wave equation with a sound speed coefficient depending on the spatial coordinates and time. The data in the inverse problem are measurements of time-dependent acoustic pressure in some spatial domain. Using these data, it is necessary to determine the positions of local acoustic inhomogeneities (spatial sound speed distributions), which change over time. A special idealized sounding model is used, in which, in particular, it is assumed that the spatial sound speed distribution changes little in the interval between source time pulses. With such a model, the inverse problem is reduced to solving three-dimensional Fredholm linear integral equations for each sounding time interval. Using these solutions, the spatial sound speed distributions are calculated in each sounding time interval. When a special (plane-layer) geometric scheme for the location of the observation and sounding domains is included in the sounding scheme, the inverse problem can be reduced to solving systems of one-dimensional linear Fredholm integral equations, which are solved by well-known methods for regularizing ill-posed problems. This makes it possible to solve the three-dimensional inverse problem of determining the nonstationary sound speed distribution in the sounded medium on a personal computer of average performance for fairly detailed spatial grids in a few minutes. The efficiency of the corresponding algorithm for solving a three-dimensional nonstationary inverse sounding problem in the case of moving local acoustic inhomogeneities is illustrated by solving a number of model problems.

Nartov F.A., Williams R.P., Khokhlova V.A. «Electronic Focus Steering Capabilities of a Diagnostic-Type Linear Ultrasound Array Designed for High Power Therapy and Its Visualization» Acoustical Physics, 70, № 1, с. 165-174 (2024)

The focus steering capabilities of a 1 MHz linear phased array transducer (64 rectangular elements, 14.8×51.2 mm aperture) intended for drug delivery applications in abdominal organs were assessed and compared with its design-stage computer model. Acoustic fields generated by the transducer and predicted by the models of an ideal array with uniformly vibrating elements and either a plane or a cylindrically focused surface were simulated using the Rayleigh integral and angular spectrum methods. The boundary conditions for the transducer were reconstructed from acoustic holography measurements performed for selected focusing configurations of the array and also synthesized from holography data measured for each of its individual elements. It was shown that the transducer field with electronic focus steering can be accurately synthesized based on the holography data of its elements, which significantly simplified acoustic field characterization. Variability of the power and directivity patterns of the array elements were analyzed. A twofold smaller range of electronic steering in the transverse direction for the transducer compared to its computer model is discussed.

Kurazhova V. «Adult Speech in Different Emotional States: Temporal and Spectral Features» Acoustical Physics, 70, № 1, с. 175-181 (2024)

The aim of the study is to determine individual features of adult speech in different emotional states. The acoustic speech characteristics of 12 adult native Russian speakers were studied. The speech of informants uttering meaningless phrase in different emotional states was audio recorded: joy, anger, sadness, fear, and neutral. The temporal and spectral characteristics of speech were analyzed in the Cool Edit Pro sound editor. The maximum pitch range in male speech is revealed in phrases uttered in a neutral state and a state of joy; the minimum, in a state of sadness. For female speech, the maximum pitch range is in a state of joy and in a state of anger; the minimum, in a state of sadness and in a neutral state. The pitch range in female speech is larger than that in male speech. For seven informants, it was shown that the duration of utterances in a state of sadness was longer compared to other states, and in a state of joy, on the contrary, it was minimal. Both male and female utterances in a state of joy were characterized by maximum pitch range values; conversely, in a state of sadness, by minmum values. Pauses between words in utterances in a state of sadness were detected in both men and women. Thus, differences in the temporal and spectral characteristics of utterances in different emotional states are revealed. The individual features of the manifestation of the emotional state in the speech of adults are determined.

Makarov S., Osipov D.S. «Voice Identity Recognition Based on the Parameters of the Spectral Voice Source Model» Acoustical Physics, 70, № 1, с. 182-188 (2024)

The information content of the parameters of a spectral voice source model in an automatic voice identity recognition problem is studied. For the voice parameters, the identity recognition error was 20.8%; using these parameters together with the pitch period reduced the error to 13.8%. Lastly, the combined use of the spectral model parameters with the pitch period and mel-frequency cepstral coefficients provided the highest accuracy (the recognition error was 1.2%).

Vjuginova A., Vjuginov S.N., Novik A.A. «Simulation of Ultrasonic Tools for Cutting Honeycomb Panels Made of Aluminum and Aramid (Kevlar)» Acoustical Physics, 70, № 1, с. 189-193 (2024)

Honeycomb panels made of aluminum and composite materials aramid, or Kevlar–are widely used in aviation, space, automotive, and other fields due to their unique characteristics: high strength and rigidity, low density, and good thermal insulation properties. However, the mechanical processing of products made of honeycomb materials faces several difficulties, and one of the technologies that effectively solves the problems of cutting products made of honeycomb materials is ultrasonic cutting. In this paper, the finite element method is used to study the frequency properties necessary for designing tools for ultrasonic cutting of products made of honeycomb materials with operating frequencies around 20 kHz and various geometric parameters for cutting different variants of honeycomb constructions. The results of analyzing the wave dimensions of specialized ultrasonic triangular and disk-type instruments depending on geometry features are shown, along with the experimental results for a number of developed variants.

Subbotkin O. «Analysis of the Vibrational Process Inside an Acoustic Interference Array Using the Reverberation Matrix Method» Acoustical Physics, 70, № 1, с. 194-207 (2024)

The theoretical study of sound field formation in an acoustic interference array presented in this article is motivated by an analysis of the physical principle of operation of a highly directional interference microphone. One of the objectives of the study is to determine the sound pressure acting on the microphone membrane inside the array. The sound field inside the interference array is analyzed using a matrix method, similar to the reverberation matrix method. The solution is formally represented as a Schwarzschild series. The result calculated by this method agrees well with the experimental data.