Acoustical Physics最新文献

{"title":"Finite Element Modeling of Hydrodynamic Noise Arising in a Flow Around Elastic Bodies","authors":"A. S. Suvorov,&nbsp;E. M. Sokov,&nbsp;A. L. Virovlyansky,&nbsp;V. O. Eremeev,&nbsp;N. V. Balakireva","doi":"10.1134/S1063771023601206","DOIUrl":"10.1134/S1063771023601206","url":null,"abstract":"<p>A finite element method is presented for calculating hydrodynamic noise excited by turbulent fluid fluctuations in the presence of an elastic body. The conventional approach to solving this problem by direct solution of the Lighthill equation requires a large amount of calculations. It is demonstrated that the situation is considerably simplified when noise components are calculated at relatively low frequencies, which correspond to wavelengths that exceed the dimensions of the turbulent zone. In this case, the noise field can be expressed in terms of turbulent fluctuations in pressure on the surface of an elastic body, which is found in the incompressible fluid approximation. The article is based on a report presented at the IX Russian Conference “Computational Experiment in Aeroacoustics and Aerodynamics,” Svetlogorsk, September 26–October 1, 2022.</p>","PeriodicalId":455,"journal":{"name":"Acoustical Physics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acoustic Analogy with High-Order Time Derivatives for Far-Field Acoustic Predictions","authors":"Minjun Park,&nbsp;Hakjin Lee","doi":"10.1134/S106377102210013X","DOIUrl":"10.1134/S106377102210013X","url":null,"abstract":"<p>The numerical method is proposed for predicting the far-field noise using Ffowcs Williams–Hawkings (FW–H) equation with high-order finite-difference method for the time derivative. The results of this method for second-, fourth-, and sixth-order finite difference approximations are compared with that of analytic applications, such as monopole and dipole. It is observed that the use of the high-order time derivatives is an efficient approach to improve the prediction accuracy of the radiated acoustic pressure, particularly when the temporal resolution is not sufficiently high owing to the limited time step size. Our findings in this study provide evidence that for higher-order approximations, the RMS error for the first and second derivatives is smaller. In addition, the RMS error for the sixth-order approximation decreases considerably compared to that for the second-order approximation, with an increase in the number of points per period. This study and its results are expected to serve as a guide for noise prediction, indicating the temporal accuracies of the acoustic analogy according to the high-order approximation of time derivatives<i>.</i></p>","PeriodicalId":455,"journal":{"name":"Acoustical Physics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling Acoustic Processes of the Interaction of Cells of Sound-Absorbing Structures of Aircraft Engines","authors":"P. V. Pisarev,&nbsp;A. A. Pankov,&nbsp;A. N. Anoshkin,&nbsp;K. A. Akhunzyanova","doi":"10.1134/S1063771023600912","DOIUrl":"10.1134/S1063771023600912","url":null,"abstract":"<p>Physical and mathematical numerical models have been developed to predict the effective acoustic properties of sound-absorbing honeycomb structures at sound pressure levels of 100 and 130 dB with normal sound wave incidence. The sound absorption coefficients and patterns of acoustic interactions of cells installed at the end of a cylindrical duct with normal sound wave incidence on them were studied by numerical mathematical and physical modeling. The sound absorption efficiency of single and groups of resonators of various shapes and sizes is estimated, and unique combinations of cells in groups are identified, taking into account their acoustic interactions. Representative samples of fragments of sound-absorbing structures were 3D-printed; laboratory tests of the samples were carried out with an interferometer with a normal sound wave incidence on the cells at a sound pressure level of 130 dB.</p>","PeriodicalId":455,"journal":{"name":"Acoustical Physics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140010069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Intriguing Feature of Linear Motors Driven by Surface Acoustic Waves","authors":"Li-Ping Cheng,&nbsp;Li Fan,&nbsp;Xiao-Dong Xu,&nbsp;Shu-Yi Zhang","doi":"10.1134/S1063771023600675","DOIUrl":"10.1134/S1063771023600675","url":null,"abstract":"<p>Motors driven by surface acoustic waves (SAWs) have been extensively investigated due to their potential applications in various environments. One of the problems we are confronted with is the lifetime of the substrate which supports SAWs since it becomes fragile when large-amplitude SAWs are excited on the substrate. In order to prolong the lifetime of the substrate, we propose to apply modulated driving voltage with a duty ratio to the interdigital transducers. With the implementation of such a proposal, we found an intriguing phenomenon which is out of expectation, i.e., when the driving voltage is high, the slider speed under modulated driving with a suitable duty ratio might be larger than that with the continuous driving<i>.</i></p>","PeriodicalId":455,"journal":{"name":"Acoustical Physics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of Tracks of Resonance Frequencies of the Vocal Tract","authors":"A. S. Leonov,&nbsp;V. N. Sorokin","doi":"10.1134/S1063771023601140","DOIUrl":"10.1134/S1063771023601140","url":null,"abstract":"<div><p>A new method for estimating formant frequency tracks of the vocal tract for arbitrary speech segments is proposed. The method uses the ratio of two Fourier transforms of a speech signal with special exponential-type windows depending on some parameter. This ratio is used for specific points in time and is considered as a function of frequency and parameter. By analyzing, for several parameter values, the distribution of minimum points (in terms of frequency) for the phase of this ratio and/or a similar distribution of extreme points for its amplitude, it is possible to estimate formant frequencies from the peaks of these distributions. A mathematical study is presented that substantiates this approach. A series of numerical experiments were carried out on the processing of synthetic and real speech signals, which confirmed the performance capabilities of the proposed formant evaluation method. In particular, in experiments with synthesized vowels, it was found that the error in estimating their resonance frequencies is small and stable with respect to additive noise up to a signal-to-noise ratio of 5 dB. For real speech, the method makes it possible to calculate the formant frequency tracks for both sounds with vocal excitation and for voiceless fricatives, aspirated plosives, and whispered speech.</p></div>","PeriodicalId":455,"journal":{"name":"Acoustical Physics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of the Acoustic and Aerodynamic Characteristics of Lobed Nozzles","authors":"V. F. Kopiev,&nbsp;I. V. Khramtsov,&nbsp;E. S. Cherenkova,&nbsp;M. Yu. Zaitsev,&nbsp;Yu. V. Bersenev,&nbsp;V. V. Ershov,&nbsp;O. Yu. Kustov,&nbsp;R. V. Bulbovich","doi":"10.1134/S1063771023600353","DOIUrl":"10.1134/S1063771023600353","url":null,"abstract":"<div><p>The results of a study of noise reduction in a subsonic turbulent jet using a lobed nozzle section are presented. Lobed nozzles with 6–12 lobes of different heights were considered. The experiments were carried out in two anechoic chambers: an anechoic chamber with aerodynamic noise sources at the Laboratory of Noise Generation Mechanisms and Modal Analysis of PNRPU and the AC-2 anechoic chamber with flow at TsAGI. The sound field of a subsonic jet flowing from a lobed nozzle was compared with the sound field of an equivalent round jet. The paper demonstrates ways to expand the frequency range in which jet noise is reduced using lobed nozzles. The thrust losses in lobed nozzles based on RANS calculation are estimated.</p></div>","PeriodicalId":455,"journal":{"name":"Acoustical Physics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on Denoising Method of Surface Defect Signal of Rail Based on CEEMD and Wavelet Soft Threshold","authors":"Guo Hua-Ling,&nbsp;Zhenh Bin,&nbsp;Liu Li-Ping,&nbsp;Liu Hui","doi":"10.1134/S1063771022600504","DOIUrl":"10.1134/S1063771022600504","url":null,"abstract":"<p>Laser ultrasonic detection of rail defects has become a new method of rail nondestructive testing. Obtaining accurate rail defect signal is a prerequisite to judge the size of defects and avoid train accidents and ensure driving safety. In order to effectively improve the SNR of defect echo, a denoising algorithm combining CEEMD and wavelet soft threshold was proposed. First, CEEMD decomposition was performed on the signal to determine the demarcation point <i>k</i> of IMF components by autocorrelation function. The signal after <i>k</i> + 1 component was reconstructed. Then, the reconstructed signals were decomposed by wavelet transform. The high frequency coefficients after soft threshold processing and the low frequency coefficients of wavelet transform were reconstructed to complete the denoising of rail surface defect signals. The rail with defect of a depth of 0.5 mm and a width of 0.5 mm was tested and verified by laser ultrasonic experiment. By experiment the denoising method combining CEEMD and wavelet soft threshold suppressed effectively the noise. It retained the detailed characteristics of the defective reflected waves. It achieved the good denoising characteristics. It improves the signal-to-noise ratio by 7.12 and 0.77 dB, respectively, over the EMD denoising algorithm and CEEMD denoising algorithm at 1 dB noise intensity and improves the signal-to-noise ratio by 3.37 and 1.23 dB, respectively, over the EMD denoising algorithm and CEEMD denoising algorithm at 20 dB noise intensity.</p>","PeriodicalId":455,"journal":{"name":"Acoustical Physics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discrete Acoustics: ARMA-Modeling of Time Processes, Theory","authors":"Y. I. Bobrovnitskii,&nbsp;I. A. Karpov","doi":"10.1134/S106377102360095X","DOIUrl":"10.1134/S106377102360095X","url":null,"abstract":"<p>In physics, in particular, acoustics, time is traditionally considered as a continuous coordinate. Some exception is signal processing, where sampling is necessary for calculations on computers. But all acoustic problems are formulated and solved using time-continuous models described by differential equations and their solutions in the form of continuous time functions. Meanwhile, these problems can be formulated and solved in an equivalent way using discrete-time models described by finite-difference equations and their solutions in the form of time series. As the experience of some other fields of science, for example, control theory, shows, the discrete approach has a number of advantages over the continuous approach, the use of which greatly facilitates the solution of many problems. This paper aims to partially fill the gap in acoustics that exists here and is aimed at creating the theoretical foundations of a discrete-time approach to solving acoustic problems. The paper is limited to the consideration of one oscillatory system widely used in acoustics—a linear structure with <i>N</i> degrees of freedom consisting of lumped inertial, elastic and dissipative elements, to which, in particular, the finite element method leads. For several continuous models of this system, equivalent discrete-time models are constructed in the paper, finite-difference equations are derived and their solutions are obtained. The criterion of equivalence of continuous and discrete models in the paper is the mathematically exact equality of the corresponding solutions at all discrete points in time. Based on this criterion, analytical relations have been established between the parameters of continuous and discrete models and their equations, which make it possible to build its discrete-time model based on a continuous model of the system and, conversely, to build its continuous model based on a known discrete model. Special attention is paid in the paper to the forced vibrations of the system under the action of kinematic excitation, which is important in many acoustic problems, whereas in the literature only force excitation is considered. The paper also discusses one of the most useful properties of discrete modeling—the simplicity of constructing discrete models based on experimentally measured signals. A corresponding example is given. Note that the term “ARMA-model” is an abbreviation for “autoregressive and moving average model”, generally accepted in control theory, systems theory and other fields of science.</p>","PeriodicalId":455,"journal":{"name":"Acoustical Physics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reduction of the Spin–Phonon Coupling of Quadrupole Nuclei in NaF Crystals under Magnetic Saturation","authors":"V. M. Mikushev,&nbsp;A. M. Rochev,&nbsp;E. V. Charnaya","doi":"10.1134/S1063771023601103","DOIUrl":"10.1134/S1063771023601103","url":null,"abstract":"<p>The rate of nuclear spin-lattice relaxation is determined by the efficiency of interaction between thermal phonons and nuclear spins. The results on reducing the efficiency of spin–phonon coupling by suppressing the contribution from paramagnetic centers to quadrupole nucleus relaxation are presented. The suppression has been performed by continuous magnetic action at the Larmor frequency. It is shown that, as in the presence of an acoustic field, the rate of spin-lattice relaxation of ²³Na nuclei in a sodium fluoride crystal at magnetic saturation of the NMR signal does not change in the region of a negative average spin temperature. In the region of positive spin temperature, the rate of relaxation of ²³Na spins significantly decreases and nuclear magnetization recovery with time is described by the sum of two exponentials. The contribution from nuclear spins with a lower efficiency of spin–phonon coupling, corresponding to the exponential with a long relaxation time, increases with increasing saturating field intensity. It is demonstrated that the efficiency of spin–phonon coupling for ¹⁹F nuclei, which do not have the quadrupole moment, does not change under the saturation conditions. The results obtained can be used for analyzing the structure of real crystals.</p>","PeriodicalId":455,"journal":{"name":"Acoustical Physics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Laser Vibrometry of Shear Waves in a Layer of a Gel-Like Medium","authors":"Sh. A. Asfandiyarov,&nbsp;A. A. Agafonov,&nbsp;A. I. Korobov,&nbsp;V. G. Andreev","doi":"10.1134/S1063771023601097","DOIUrl":"10.1134/S1063771023601097","url":null,"abstract":"<p>A laser scanning vibrometer was used to measure the amplitudes and phases of the vibrational velocity of shear waves excited by a one-dimensional source in the form of a narrow rectangular bar in a gel-like medium. The vibrations of 26 plates reflecting the laser beam and located inside an optically transparent phantom along a segment with a length of 84.5 mm at a distance of 20 mm from the source were measured. The angular distributions of the amplitude and phase of shear waves at discrete frequencies from 59 to 500 Hz were measured in continuous mode. In pulsed mode, the vibrator excited a pulse in the medium with a duration of 1.5 periods of the 300 Hz frequency. The amplitudes and phases of shear waves were calculated by fast Fourier transform of the time profile of the vibration velocity of the plates with a duration of 50 ms. The angular amplitude distributions measured in the pulsed and continuous modes are qualitatively the same. At all frequencies, the distributions are symmetrical with respect to the vertical axis. The maximum oscillation amplitude is observed at angles close to ±45°. The velocity of shear waves, calculated from the measured phase distributions, increases from 2 to 2.5 m/s with a change in frequency from 50 to 500 Hz. It is shown that this velocity behavior is well described by a relaxation model of the medium with one relaxation time equal to 0.3 ms. Shear wave attenuation depends on frequency and exceeds 1 cm^–1 for waves with frequencies above 250 Hz. The maximum attenuation per wavelength is observed near the relaxation frequency of the medium in the 300–400 Hz range. The results can be used to optimize devices for measuring the elasticity of soft tissues.</p>","PeriodicalId":455,"journal":{"name":"Acoustical Physics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}