Artykuły w czasopismach: „Moving Acoustic Source”

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Hou, Jiacheng, i Zhongquan Charlie Zheng. "Simulation of near-ground signals from a flying source on UAV over a building structure". Journal of the Acoustical Society of America 151, nr 4 (kwiecień 2022): A36. http://dx.doi.org/10.1121/10.0010577.

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Acoustic signals near the ground generated by a moving source on a fly-by UAV are simulated around a house. The simulation is carried out using a time-domain acoustics solver that can simulate acoustic propagations with the specified moving source, ground properties, and building geometries. The source on a UAV is approximated by a broadband source moving at a constant speed. The long-range three-dimensional computation is developed with a ground as a rigid or porous medium and a residential house with realistic geometries. Time histories and histograms of the near-ground sensors at different locations around the house are analyzed with their different behaviors due to Doppler shift, ground effect, and acoustic interference from the house structures. Comparisons will be made with literature results and available measured data.

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Cevher, V., i J. H. McClellan. "Acoustic node calibration using a moving source". IEEE Transactions on Aerospace and Electronic Systems 42, nr 2 (kwiecień 2006): 585–600. http://dx.doi.org/10.1109/taes.2006.1642574.

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Yin, Junhui, Chao Xiong i Wenjie Wang. "Acoustic Localization for a Moving Source Based on Cross Array Azimuth". Applied Sciences 8, nr 8 (1.08.2018): 1281. http://dx.doi.org/10.3390/app8081281.

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Acoustic localization for a moving source plays a key role in engineering applications, such as wildlife conservation and health protection. Acoustic detection methods provide an alternative to traditional radar and infrared detection methods. Here, an acoustic locating method of array signal processing based on intersecting azimuth lines of two arrays is introduced. The locating algorithm and the precision simulation of a single array shows that such a single array has good azimuth precision and bad range estimation. Once another array of the same type is added, the moving acoustic source can be located precisely by intersecting azimuth lines. A low-speed vehicle is used as the simulated moving source for the locating experiments. The length selection of short correlation and moving path compensation are studied in the experiments. All results show that the proposed novel method locates the moving sound source with high precision (<5%), while requiring fewer instruments than current methods.

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Gaudette, Jason E., i James A. Simmons. "Linear time-invariant (LTI) modeling for aerial and underwater acoustics". Journal of the Acoustical Society of America 153, nr 3_supplement (1.03.2023): A95. http://dx.doi.org/10.1121/10.0018285.

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Most newcomers to acoustic signal processing understand that linear time-invariant (LTI) filters can remove out-of-band noise from time series signals. What many acoustics researchers may not realize is that LTI models can be applied much more broadly, including to non-linear and time-variant systems. This presentation covers an overview of the autoregressive (AR), moving-average (MA), and autoregressive moving-average (ARMA) family of LTI models and their many useful applications in acoustics. Examples include analytic time-frequency processing of multi-component echolocation signals, fractional-delay filtering for acoustic time series simulations, broadband acoustic array beamforming, adaptive filtering for noise cancelation, and system identification for acoustic equalizers (i.e., flattening the frequency response of a source-receiver pair). This talk serves as a brief tutorial and inspiration for researchers who want to expand their use of signal processing, especially those in the fields of animal bioacoustics, aerial acoustics, and underwater acoustics.

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Sam Hun, Hanisah, Siti Norulakmal Che Abu Bakar i Anis Nazihah Mat Daud. "Acoustic Doppler effect experiment: integration of frequency sound generator, tracker and visual analyser". Physics Education 58, nr 2 (26.01.2023): 025015. http://dx.doi.org/10.1088/1361-6552/acb129.

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Abstract This study was conducted to design an acoustic Doppler effect experimental setup by integrating the frequency sound generator application, tracker and visual analyser. The experimental setup was evaluated by determining the frequency of the sound source in four cases; (a) a stationary observer and a moving sound source, (b) a stationary sound source and a moving observer, (c) a sound source and an observer are moving in the same direction and (d) a sound source and an observer are moving in the opposite direction. The findings showed that the percentage errors for the calculated values of the sound source frequency were less than 0.40% compared to the reference values for all four cases. Hence, the proposed acoustic Doppler effect experimental setup can be used to improve the acoustic Doppler effect concept among students.

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Whitaker, Steven, Andrew Barnard, George D. Anderson i Timothy C. Havens. "Through-Ice Acoustic Source Tracking Using Vision Transformers with Ordinal Classification". Sensors 22, nr 13 (22.06.2022): 4703. http://dx.doi.org/10.3390/s22134703.

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Ice environments pose challenges for conventional underwater acoustic localization techniques due to their multipath and non-linear nature. In this paper, we compare different deep learning networks, such as Transformers, Convolutional Neural Networks (CNNs), Long Short-Term Memory (LSTM) networks, and Vision Transformers (ViTs), for passive localization and tracking of single moving, on-ice acoustic sources using two underwater acoustic vector sensors. We incorporate ordinal classification as a localization approach and compare the results with other standard methods. We conduct experiments passively recording the acoustic signature of an anthropogenic source on the ice and analyze these data. The results demonstrate that Vision Transformers are a strong contender for tracking moving acoustic sources on ice. Additionally, we show that classification as a localization technique can outperform regression for networks more suited for classification, such as the CNN and ViTs.

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Lloyd, S. F., C. Jeong, H. N. Gharti, J. Vignola i J. Tromp. "Spectral-Element Simulations of Acoustic Waves Induced by a Moving Underwater Source". Journal of Theoretical and Computational Acoustics 27, nr 03 (wrzesień 2019): 1850040. http://dx.doi.org/10.1142/s2591728518500408.

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In this study, we model acoustic waves induced by moving acoustic sources in three-dimensional (3D) underwater settings based on a spectral-element method (SEM). Numerical experiments are conducted using the SEM software package SPECFEM3D_Cartesian, which facilitates fluid–solid coupling and absorbing boundary conditions. Examples presented in this paper include an unbounded fluid truncated by using absorbing boundaries, and a shallow-water waveguide modeled as a fluid–solid coupled system based on domain decomposition. In the numerical experiments, the SEM-computed pressures match their analytical counterparts. SEM solutions of pressures at points behind and ahead of modeled moving acoustic sources show a frequency shift, i.e., a Doppler effect, which matches the analytical solution. This paper contributes to the field of passive sonar-based detection of moving acoustic sources, and addresses the challenge of computing wave responses generated by side-scan sonar by using moving sources of continuous signals.

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Ghorbaniasl, Ghader, Zhongjie Huang, Leonidas Siozos-Rousoulis i Chris Lacor. "Analytical acoustic pressure gradient prediction for moving medium problems". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, nr 2184 (grudzień 2015): 20150342. http://dx.doi.org/10.1098/rspa.2015.0342.

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In this paper, an acoustic pressure gradient formula capable of accounting for constant uniform flow effects is suggested. Acoustic pressure gradient calculation is key for acoustic scattering problems, because it may be used to evaluate the hardwall boundary condition. Realistic cases of rotating machines may be evaluated in a moving frame of reference and as such, an acoustic pressure gradient formula capable of accounting for constant uniform flow effects finds significant application. A frequency domain formulation was thus derived for periodic noise source motion located in a moving medium. The suggested formula is mathematically compact and easy to implement. It may offer us significant advantages when tonal noise emissions are dominant, thus finding application potential in acoustic scattering problems in rotating machines in a constant uniform flow. Moreover, the formula contains no Doppler factor, thus facilitating noise prediction for sources in supersonic motion.

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Valdivia, Nicolas P. "Near-field acoustic holography for underwater moving surfaces". Journal of the Acoustical Society of America 153, nr 3_supplement (1.03.2023): A299. http://dx.doi.org/10.1121/10.0018923.

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Near-field acoustic holography has been the standard technique to accurately image static structure vibration from nearby acoustic pressure measurements. The classical application bases the method on the stable solution of an integral surface representation of the acoustic pressure. In this work, we will be concerned with the extension of NAH to image a vibrating structure moving underwater. In an underwater medium, even at slow speeds, the action between the flow and structure produces many radiation sources that could severely limit the accuracy of the integral surface representation used for static NAH. Using the Lighthill acoustic analogy, we use an integral surface representation for the structure’s radiated sound and a quadrupole source that models the corresponding flow-induced sound. Finally, we will justify the validity of the proposed method for COMSOL numerically generated pressure data that results from the internal excitation of a cylindrical structure moving over an underwater medium. This work has been supported by the Office of Naval Research.

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ARIAS, E., C. H. G. BÉSSA i N. F. SVAITER. "AN ANALOG FLUID MODEL FOR SOME TACHYONIC EFFECTS IN FIELD THEORY". Modern Physics Letters A 26, nr 31 (10.10.2011): 2335–44. http://dx.doi.org/10.1142/s0217732311036784.

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We consider the sound radiation from an acoustic point-like source moving along a supersonic ("space-like") trajectory in a fluid at rest. We call it an acoustic "tachyonic" source. We describe the radiation emitted by this supersonic source. After quantizing the acoustic perturbations, we present the distribution of phonons generated by this classical tachyonic source and the classical wave interference pattern.

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Lilley, Geoffrey M. "The Source of Aerodynamic Noise". International Journal of Aeroacoustics 2, nr 3 (lipiec 2003): 241–53. http://dx.doi.org/10.1260/147547203322986133.

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This paper is a tribute to Alan Powell's achievements and his extensive publications in hydro and aeroacoustics.1 The theory of Aerodynamic Noise was established by Sir James Lighthill in 1952. The beauty of Lighthill's treatment was that he based this theory on the exact Navier-Stokes equations and showed, by their rearrangement, how the source of aerodynamic noise could be obtained from exact time-accurate calculations or experiment. Lighthill used the emission or propagation theory whereby an observer in a uniform medium at rest receives acoustic radiation from a distribution of moving sources of sound. Their properties are found using an acoustic analogy. The relevant fluctuations in a turbulent fluid flow can be expressed in terms of Lighthill's stress tensor Tij, which is used to define a distribution of equivalent acoustic sources, which move through an otherwise uniform stationary fluid. An alternative procedure is to concentrate on the acoustic generation and to regard the sources of sound at rest or in motion in a uniform medium moving at a constant speed. (The approach can be extended to consider any arbitrary mean fluid motion.) The advantage of the present approach, involving the convective wave equation is that flow-acoustic interaction becomes part of the solution. In Lighthill's theory, flow-acoustic interaction is either ignored or at best is included as an equivalent source. The purpose of the present paper is to show there is no unique source of aerodynamic noise for it depends on the flow quantity used to describe the radiated sound. The convective wave equation is introduced and shown to involve similar sources to those found by Lighthill for the wave equation in a medium at rest. The source function found for the convective wave equation for a turbulent flow is shown to involve a modified Lighthill's stress tensor, which is non-linear in velocity and temperature fluctuations. It is further shown when the rate of dilatation covariance is examined, which can be derived from Lighthill's solution, that this small quantity, which Lighthill so carefully treated in retaining the exact properties of the compressible flow, is itself directly responsible for the rate of change of volume in the fluid and the creation of the noise which is radiated from the turbulent flow.

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Zhao, Liuxian, Lihua Tang, Yuxin Liu, Zhaoyong Sun, Qimin Liu i Chuanxing Bi. "Passive directivity detection of acoustic sources based on acoustic Luneburg lens". Journal of the Acoustical Society of America 154, nr 2 (1.08.2023): 594–601. http://dx.doi.org/10.1121/10.0020541.

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This article reports an acoustic Luneburg lens (ALL) design with graded refractive index for passive directivity detection of acoustic sources. The refractive index profile of the lens is realized based on square pillars with graded variation of their dimensions. Numerical and experimental studies are conducted to investigate the performance of directivity detection. The results demonstrate that the lens designed and developed in this study is capable of precisely detecting the directivity of one acoustic source. Furthermore, the directivities of two acoustic sources can also be detected with a resolution of 15°. In addition, different methods are investigated, including introducing phase difference by tuning input signals or moving ALL, and increasing the aperture size of ALL, to improve the resolution of dual sources directivity detection.

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Ericson, Mark A. "Velocity Judgments of Moving Sounds in Virtual Acoustic Displays". Proceedings of the Human Factors and Ergonomics Society Annual Meeting 44, nr 22 (lipiec 2000): 710–13. http://dx.doi.org/10.1177/154193120004402256.

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A pure tone sound source, moving along a linear left-to-right trajectory, was simulated over headphones. Six attributes of the object motion were varied independently in a randomized block, factorial design experiment. The independent variables included: 1) sound source velocity, 2) distance from the observer, 3) interaural time delays, 4) Doppler frequency shifts, 5) overall intensity and 6) signal duration. Eight listeners estimated the magnitude of the velocity of the simulated moving sound source in miles per hour. Five of the six independent variables were found to make statistically significant (p<.05) contributions to estimates of velocity magnitude. Correct velocity estimates were found to be moderately correlated with the minimal distance between the trajectory path and the observer, Doppler frequency shifts, and intensity changes. The simulated velocity of the sound source and interaural time delay variables, although statistically significant, explained less than ten percent of the variance in the data. Implications of these research findings for virtual acoustic display design are discussed.

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Gemba, Kay L., Heriberto J. Vazquez, Jit Sarkar, Jeffrey D. Tippman, Bruce Cornuelle, William S. Hodgkiss i W. A. Kuperman. "Moving source ocean acoustic tomography with uncertainty quantification using controlled source-tow observations". Journal of the Acoustical Society of America 151, nr 2 (luty 2022): 861–80. http://dx.doi.org/10.1121/10.0009268.

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Zabotin, Nikolay A., Oleg A. Godin, Paul C. Sava i Liudmila Y. Zabotina. "Tracing Three-Dimensional Acoustic Wavefronts in Inhomogeneous, Moving Media". Journal of Computational Acoustics 22, nr 02 (17.04.2014): 1450002. http://dx.doi.org/10.1142/s0218396x14500027.

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We present a numerical implementation of an alternative formulation of the geometrical, or ray, acoustics, where wavefronts rather than rays are the primary objects. Rays are recovered as a by-product of wavefront tracing. The alternative formulation of the geometrical acoustics is motivated, first, by the observation that wavefronts are often more stable than rays at long-range sound propagation, and, second, by a need for computationally efficient modeling of high-frequency acoustic fields in three-dimensionally inhomogeneous, moving or motionless fluids. Wavefronts are found as a finite-difference solution to a system of partial differential equations, which is equivalent to the eikonal equation and is a direct implementation of the intuitive Huygens' wavefront construction. The finite-difference algorithm is an extension of the approach originally developed in the framework of an open source Madagascar project. Benchmark problems, which admit exact, analytic solutions of the eikonal equation, are formulated and utilized to verify the finite-difference wavefront tracing algorithm. Huygens' wavefront tracing (HWT) is applied to modeling sound propagation in three-dimensionally inhomogeneous ocean and atmosphere.

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Searle, Stephen J. "Efficient matched processing for localisation of a moving acoustic source". Signal Processing 85, nr 9 (wrzesień 2005): 1787–804. http://dx.doi.org/10.1016/j.sigpro.2005.03.012.

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Akins, Franklin H., i William Kuperman. "Modal-MUSIC extensions". Journal of the Acoustical Society of America 152, nr 4 (październik 2022): A201. http://dx.doi.org/10.1121/10.0016028.

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Modal-MUSIC [Akins and Kuperman, JASA Express Lett. 2(7), 074802 (2022)] is a variant of the well-known MUSIC plane wave algorithm that extracts direction of arrivals (DOA’s) from data containing multiple sources. Modal-MUSIC, rather than extract the DOA’s of the multiple sources, extracts the acoustic normal modes from incoherently summed data from multiple and/or moving sources received on a short vertical array. The method uses the local sound speed profile but does not require bottom geophysical information. We discuss extensions of the method that include using shorter arrays, geophysical-inversion and the additional application of synthetic source aperture [Akins and Kuperman, J. Acoust. Soc. Am. 150(1), 270–289 (2021)] to enhance source localization.

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Gibbs, George. "Measurement of acoustic source data of taxiing aircraft for noise modelling". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, nr 3 (1.02.2023): 4817–25. http://dx.doi.org/10.3397/in_2022_0695.

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Noise from airport ground activities can be a significant contribution to the ambient sound climate in communities close to airports. The shortfall in robust acoustic source data for taxiing aircraft is a limitation to the accuracy of noise modelling supporting impact assessments associated with changes in airport infrastructure and operations. The aim of this project was to develop a robust measurement methodology for the purpose of obtaining acoustic source data of taxiing aircraft. The project addressed two major challenges: the theoretical principle and experimental design for characterizing complex moving sources (i.e. the sound power, spectra and directivity); and the practical problems involved in on-site measurement. The theoretical principle is to of consider an aircraft, moving in-line past a microphone, as reciprocally equivalent to a stationary aircraft alongside a line-array of microphones. Increasing the number of microphones in the array is equivalent to increasing the number of angles in the polar distribution plots.

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Okoyenta, Augustus R., Haijun Wu, Xueliang Liu i Weikang Jiang. "A Short Survey on Green’s Function for Acoustic Problems". Journal of Theoretical and Computational Acoustics 28, nr 02 (czerwiec 2020): 1950025. http://dx.doi.org/10.1142/s2591728519500257.

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Green’s functions for acoustic problems is the fundamental solution to the inhomogeneous Helmholtz equation for a point source, which satisfies specific boundary conditions. It is very significant for the integral equation and also serves as the impulse response of an acoustic wave equation. They are important for acoustic problems that involve the propagation of sound from the source point to the observer position. Once the Green’s function, which satisfies the necessary boundary conditions, is obtained, the sound pressure at any point away from the source can be easily calculated by the integral equation. The major problem faced by researchers is in the process of constructing these Green’s functions which satisfy a specific boundary condition. The aim of this work is to review some of these fundamental solutions available in the literature for different boundary conditions for the ease of analyzing acoustics problems. The review covers the free-space Green’s functions for stationary source and rotational source, for both when the observer and the acoustic medium are at rest and when the medium is in uniform flow. The half-space Green’s functions are also summarized for both stationary acoustic source and moving acoustic source, derived using the image source method, equivalent source method and complex equivalent method in both time domain and frequency domain. Each of these methods used depends on the different impedance boundary conditions for which the Green’s function will satisfy. Finally, enclosed spaced Green’s functions for both rectangular duct and cylindrical duct for an infinite and finite duct is also covered in the review.

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Liu, Yuhan, Lianghao Guo, Weiyu Zhang, Chao Yan i Ge Dong. "Range estimation of a moving source using interference patterns in deep water". JASA Express Letters 2, nr 12 (grudzień 2022): 126001. http://dx.doi.org/10.1121/10.0016402.

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The frequency-range interference patterns of the acoustic field in the shadow zone of deep water correlate with the source location. However, extraction of such interference structure requires a broadband source and fails for narrowband signals. In this work, the narrowband depth-time interference patterns of the acoustic field from a moving source are investigated. Two types of time intervals in the observed patterns are derived based on the ray theory. These time intervals are correlated with the multipath arrival angles, which in turn imply the source range. The simulations and the experimental results demonstrate stable range estimations using the interference patterns.

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Gaunaurd, G. C., i L. H. Nguyen. "Acoustic Energy Radiation from Rectilinearly Moving Point Sources with Unsteady Accelerations and Source-Strengths". Acta Acustica united with Acustica 95, nr 6 (1.11.2009): 975–83. http://dx.doi.org/10.3813/aaa.918229.

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Zhang, Ao, Fang Liu i Fan Rang Kong. "Doppler Distortion Removal Method for Multiple Acoustic Sources". Applied Mechanics and Materials 373-375 (sierpień 2013): 874–79. http://dx.doi.org/10.4028/www.scientific.net/amm.373-375.874.

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In wayside fault diagnosis of train bearings, the phenomenon of Doppler distortion in the acoustic signal of moving acoustic source acquired with a microphone leads to the difficulty for signal analysis. In this paper, a new method based on Dopplerlet transform and re-sampling is proposed to eliminate the Doppler distortion of multiple acoustic sources which provide a reference for wayside fault diagnosis of train bearings. Firstly, search the parameters space to find the primary functionsDopplerlet atoms. According to the Morse acoustic theory, the instantaneous frequency of the Dopplerlet atom which we choose to remove Doppler distortion of the corresponding acoustic source can be acquired. Then, the re-sampling sequence can be established in time domain. Through the resample, the Doppler distortion can be removed. In the end of this paper, an experiment with practical acoustic signals is carried out, and the results verified the effectiveness of this method.

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ZABOTIN, NIKOLAY A., OLEG A. GODIN, PAUL C. SAVA i LIUDMILA Y. ZABOTINA. "ACOUSTIC WAVEFRONT TRACING IN INHOMOGENEOUS, MOVING MEDIA". Journal of Computational Acoustics 20, nr 03 (wrzesień 2012): 1250009. http://dx.doi.org/10.1142/s0218396x12500099.

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We extend the Huygens wavefront tracing algorithm, which is a part of an open source Madagascar project, to sound propagation in inhomogeneous, moving media and apply it to a series of benchmark tasks. One set of tasks admits exact analytic solutions and serves the purpose of validation of the new algorithm. Another set of calculations demonstrates applicability of the algorithm to the studies of wavefront dynamics and stability in ocean and atmospheric acoustics. The method is based on a system of differential equations equivalent to the eikonal equation, but formulated in the ray coordinate system. In this paper, we present a first-order, two-dimensional discretization scheme that is interpreted very simply in terms of the Huygens' principle. The method has proved to be a convenient alternative to conventional ray tracing.

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McShane, John, Parthiv Shah, Peter Kerrian, Michael Yang i Andrew White. "Advanced applications of the continuous-scan acoustic measurement method". Journal of the Acoustical Society of America 153, nr 3_supplement (1.03.2023): A55. http://dx.doi.org/10.1121/10.0018143.

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This presentation will cover recent progress in the development of continuous-scan acoustic measurement (CSAM) methods for imaging, reconstruction, and localization of spatially complex sound fields. CSAM comprises an acoustic array of slowly moving and fixed sensors coupled with position tracking to enable high-spatial-resolution partial field measurements for visualization and source characterization. In previous work, ATA has developed and demonstrated the use of a rotating array for beamforming and acoustical holography. This presentation will focus on one or more advanced applications of CSAM. Examples may include (1) quantifying spatial coherence from sound fields generated by multiple uncorrelated sources, (2) combining multiple test runs to visualize larger 2D spatial apertures and/or 3D sound fields, (3) combining high-resolution measurements with vibroacoustic models to predict scattered sound fields, and (4) exploring alternate array configurations (e.g., a spherical-surface measurement aperture).

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Wang, Rujia, i Shaoyi Bei. "Optimization of Fixed Microphone Array in High Speed Train Noises Identification Based on Far-Field Acoustic Holography". Advances in Acoustics and Vibration 2017 (1.02.2017): 1–11. http://dx.doi.org/10.1155/2017/1894918.

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Acoustical holography has been widely applied for noise sources location and sound field measurement. Performance of the microphones array directly determines the sound source recognition method. Therefore, research is very important to the performance of the microphone array, its array of applications, selection, and how to design instructive. In this paper, based on acoustic holography moving sound source identification theory, the optimization method is applied in design of the microphone array, we select the main side lobe ratio and the main lobe area as the optimization objective function and then put the optimization method use in the sound source identification based on holography, and finally we designed this paper to optimize microphone array and compare the original array of equally spaced array with optimization results; by analyzing the optimization results and objectives, we get that the array can be achieved which is optimized not only to reduce the microphone but also to change objective function results, while improving the far-field acoustic holography resolving effect. Validation experiments have showed that the optimization method is suitable for high speed trains sound source identification microphone array optimization.

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Song, Aijun, Mohsen Badiey, Julia Hsieh, Daniel Rouseff, H. C. Song i William Hodgkiss. "Acoustic communication from a moving source: Data results and model simulations." Journal of the Acoustical Society of America 126, nr 4 (2009): 2251. http://dx.doi.org/10.1121/1.3249260.

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Knobles, David P., Preston S. Wilson, Andrew R. McNeese, William Hodgkiss i Tracianne B. Neilsen. "Inference of both source and seabed characteristics from broadband signals on the New England continental slope". Journal of the Acoustical Society of America 152, nr 4 (październik 2022): A238. http://dx.doi.org/10.1121/10.0016133.

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In this study the characteristics of the modal dispersion of acoustic waves in littoral ocean environments are utilized to infer both source properties (range, depth, speed, and source level) and geoacoustic properties of the seabed. An analysis is made of broadband acoustic data (10–4500 Hz) taken during 2021–2022 on the New England continental slope over water depths from 200 to 500 m. The acoustic data are generated by both moving broadband sources and explosive sources over range scales of 1–30 km. Such range scales can reveal the nature of the modal dispersion. Conductivity, Temperature, and Depth (CTD) and Expendable Bathythermographs (XBTs) measurements provide a sparse sampling of the temporal and spatial variability of the ocean during the acoustic measurements. Along with bathymetry measurements the sound speed profiles derived from the CTDs and XBTs provide prior information for an inverse problem from which insight can be obtained on the effects of the seabed on the dispersion of broadband propagation.

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Thakkar, N. A., John A. Steel, R. L. Reuben, G. Knabe, D. Dixon i R. L. Shanks. "Monitoring of Rail-Wheel Interaction Using Acoustic Emission (AE)". Advanced Materials Research 13-14 (luty 2006): 161–68. http://dx.doi.org/10.4028/www.scientific.net/amr.13-14.161.

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This work presents the results of field measurements and laboratory studies carried out with a view to developing ways to monitor rail-wheel interaction using Acoustic Emission. It is known that impact, wear and cracking generate AE and it is therefore expected that axle loads, wheel out-of-roundness, speed and traction will influence the AE generated by an interaction. It is hoped that the extent of the effect might be sufficient to permit a measure of “interaction intensity” that could be used to quantify cumulative damage by wear and contact fatigue. In the field measurements, AE was acquired as a train with 20 moving sources of AE (20 wheels) passed a single sensor position and a laboratory rig has been devised which uses a single wheel whose condition, speed and loading can conveniently be modified. Simulated source tests have indicated that the AE wave characteristics on real rails are similar to those in the laboratory rig. A simplified analytical model, devised for AE waves propagating from a moving source(s), based on a ‘vehicle’ speed and wave damping coefficients, has been compared to measured results. As a wheel rolls towards a sensor and then away from the sensor the measured AE generally rises and falls in a predictable way. The effects of wheel and rail surface features appear to complicate the results by introducing sharp spikes in the signals. The numerical model for AE wave propagation from the moving sources (wheels) shows good agreement with the more slowly changing envelope of the signals.

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Bryukhovetski, Anatoliy, i Aleksey Vichkan'. "Determination of the green function of a pulsed acoustic source in a uniform homogeneous flow with an arbitrary Mach number". EUREKA: Physics and Engineering, nr 1 (19.01.2023): 165–76. http://dx.doi.org/10.21303/2461-4262.2023.002743.

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The wave field created by a pulsed point source of sound in a uniform homogeneous flow with an arbitrary value of the Mach number is theoretically studied. The aim of research is to obtain an analytical dependence of the sound field on physical parameters. The space-waveguide Fourier expansion of the sound field is used to solve the Cauchy problem for the wave equation in a reference frame moving together with the medium. It is only necessary to transform the spatiotemporal dependence of the source, given in a fixed frame of reference, to a dependence in a moving frame of reference. The transition to the description of the solution in the frame of reference, relative to which the medium moves at a constant velocity, is made taking into account the main properties of the generalized Dirac δ-function. Analytical dependences of the sound field on physical parameters are obtained for both subsonic and supersonic flows. A comparison is made with the results of calculations for the case of a pulsed point source moving in a medium at rest. The solution obtained in this work for the case of an impulsive source moving in a medium at rest made it possible to trace its connection with the Green's function for a stationary source in a moving medium. The analytical dependence of the obtained solution for the Green's function makes it possible to write down the explicit form of the "characteristic solution surface", that is, the "wave front". It is shown that the difference between the solutions for subsonic and supersonic motion is characterized by the position of the source relative to the moving wavefront. The calculation results can be used to describe the sound field created by an arbitrary spatiotemporal distribution of sound sources

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Whitaker, Steven, Andrew Barnard, George D. Anderson i Timothy Havens. "Ice anthropogenic classification with acoustic vector sensors using transformer neural networks". Journal of the Acoustical Society of America 151, nr 4 (kwiecień 2022): A233. http://dx.doi.org/10.1121/10.0011166.

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Acoustic classifiers are a necessary component in understanding the source. When a foreign object has been classified, physics models can be associated with the foreign object for better localization and tracking. In highly non-linear environments, like shallow ice environments, traditional classifiers cannot properly consider its compounded non-linearities: multi-path, reflective surfaces, scattering fields, and the dynamic acoustic properties of first-year ice. With such significantly distorted signals, we deploy deep neural networks to better classify different acoustic sources. We collected data from 8 different acoustic sources on the Keweenaw Waterway in Houghton, Michigan: a narrow and shallow channel covered with first-year ice. Two sources were moving and the other five were stationary; the sources did not emit simultaneously. Data were recorded using two spatially separated underwater acoustic vector sensors; their time-series data were post-processed into mel-frequency cepstral coefficients (MFCC) and analyzed with different deep neural network architectures. A deep Transformer neural network and a deep residual neural network were then compared in their ability to predict which source was emitting. Preliminary results show success with the deep Transformer neural networks.

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Ayub, M., A. Naeem i R. Nawaz. "Line-source diffraction by a slit in a moving fluid". Canadian Journal of Physics 87, nr 11 (listopad 2009): 1139–49. http://dx.doi.org/10.1139/p09-104.

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The diffraction of a cylindrical acoustic wave from a slit in a moving fluid using Myers condition (J. Sound Vib. 71, 429 (1980)) is investigated, and an improved form of the analytical solution for the diffracted field is presented. The problem is solved analytically using an integral transform, Wiener–Hopf technique, and the modified method of stationary phase. The mathematical results are well supported by graphical discussion showing how the absorbing parameter and Mach number affect the amplitude of the velocity potential.

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Ilchenko, V. V., M. M. Nikiforov, V. S. Mostovoy, B. O. Popkov, V. M. Loza O.L. i O. L. Kulskyi. "PECULIARITIES OF APPLICATION OF SEISMOACOUSTIC LOCATION FOR DETERMINATION OF MOVING OBJECTS". Collection of scientific works of the Military Institute of Kyiv National Taras Shevchenko University, nr 74 (2022): 21–30. http://dx.doi.org/10.17721/2519-481x/2022/74-03.

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The work is related to the study of surface waves in solving seismic acoustic location problems during the movement of moving objects, and in assessing the accuracy of determining the coordinates of moving objects of different origins. In solving the inverse problems of seismic acoustic location, the surfaces of the wave that occur on the Earth's surface during the movement of a moving object are studied. The accuracy of the solution of the inverse problem directly depends on the errors: determination of the time of entry of the seismic acoustic wave, the velocity characteristics of the environment, noise of various origins, the choice of the geometry of the location of sensors. The need to study surface waves, namely Rayleigh Waves and Lion Waves, is justified because they propagate on the Earth's surface. The plane of oscillation of Rayleigh waves is vertical to the Earth's surface and direction of propagation, and Lev waves have a horizontal plane of oscillation. As one of the considered problems of seismic acoustic location as a source of energy of a moving object, we take seismic energy, which occurs during human walking. Human walking is periodic. It excites impulses of displacement in the geological environment. According to the known coefficient of rigidity of the medium, it is possible to determine what will be the maximum deviation of the seismic receiver. The paper investigates surface waves, Rayleigh and Lev in solving seismic acoustic location problems during human movement, and identifies factors that affect the accuracy of determining the coordinates of a moving object. In terms of using surface waves to solve seismic location problems to identify moving objects, they have the following advantages: the energy of these waves does not disappear deep into the Earth, but propagates below its surface; their formation takes more than 60% of the energy of the source, and the formation of deep waves only 8%, such waves have much more energy; From this it can be concluded that even at low energies of the excitation source surface waves can be used to solve seismic location problems during the movement of moving objects and to assess the accuracy of determining the coordinates of these objects.

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St. George, Barrett Victor, i Barbara Cone. "Perceptual and Electrophysiological Correlates of Fixed Versus Moving Sound Source Lateralization". Journal of Speech, Language, and Hearing Research 63, nr 9 (15.09.2020): 3176–94. http://dx.doi.org/10.1044/2020_jslhr-19-00289.

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Purpose The aims of the study were (a) to evaluate the effects of systematically varied factors of stimulus duration, interaural-level difference (ILD), and direction on perceptual and electrophysiological metrics of lateralization for fixed versus moving targets and (b) to evaluate the hemispheric activity underlying perception of fixed versus moving auditory targets. Method Twelve normal-hearing, young adult listeners were evaluated using perceptual and P300 tests of lateralization. Both perceptual and P300 tests utilized stimuli that varied for type (fixed and moving), direction (right and left), duration (100 and 500 ms), and magnitude of ILD (9 and 18 dB). Listeners provided laterality judgments and stimulus-type discrimination (fixed vs. moving) judgments for all combinations of acoustic factors. During P300 recordings, listeners discriminated between left- versus right-directed targets, as the other acoustic parameters were varied. Results ILD magnitude and stimulus type had statistically significant effects on laterality ratings, with larger magnitude ILDs and fixed type resulting in greater lateralization. Discriminability between fixed versus moving targets was dependent on stimulus duration and ILD magnitude. ILD magnitude was a significant predictor of P300 amplitude. There was a statistically significant inverse relationship between the perceived velocity of targets and P300 latency. Lateralized targets evoked contralateral hemispheric P300 activity. Moreover, a right-hemisphere enhancement was observed for fixed-type lateralized deviant stimuli. Conclusions Perceptual and P300 findings indicate that lateralization of auditory movement is highly dependent on temporal integration. Both the behavioral and physiological findings of this study suggest that moving auditory targets with ecologically valid velocities are processed by the central auditory nervous system within a window of temporal integration that is greater than that for fixed auditory targets. Furthermore, these findings lend support for a left hemispatial perceptual bias and right hemispheric dominance for spatial listening.

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Sidorovskaia, Natalia, i Kun Li. "Marine compressed air source array primary acoustic field characterization from at-sea measurements". Journal of the Acoustical Society of America 151, nr 6 (czerwiec 2022): 3957–78. http://dx.doi.org/10.1121/10.0011678.

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The primary acoustic field of a standard seismic survey source array is described based on a calibrated dataset collected in the Gulf of Mexico. Three vertical array moorings were deployed to measure the full dynamic range and bandwidth of the acoustic field emitted by the compressed air source array. The designated source vessel followed a specified set of survey lines to provide a dataset with broad coverage of ranges and departure angles from the array. Acoustic metrics relevant to criteria associated with potential impacts on marine life are calculated from the recorded data. Sound pressure levels from direct arrivals exhibit large variability for a fixed distance between source and receiver; this indicates that the distance cannot be reliably used as a single parameter to derive meaningful exposure levels for a moving source array. The far-field acoustic metrics' variations with distance along the true acoustic path for a narrow angular bin are accurately predicted using a simplified model of the surface-affected source waveform, which is a function of the direction. The presented acoustic metrics can be used for benchmarking existing source/propagation models for predicting acoustic fields of seismic source arrays and developing simplified data-supported models for environmental impact assessments.

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Posson, H., i N. Peake. "The acoustic analogy in an annular duct with swirling mean flow". Journal of Fluid Mechanics 726 (10.06.2013): 439–75. http://dx.doi.org/10.1017/jfm.2013.210.

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AbstractThis paper is concerned with modelling the effects of swirling flow on turbomachinery noise. We develop an acoustic analogy to predict sound generation in a swirling and sheared base flow in an annular duct, including the presence of moving solid surfaces to account for blade rows. In so doing we have extended a number of classical earlier results, including Ffowcs Williams & Hawkings’ equation in a medium at rest with moving surfaces, and Lilley’s equation for a sheared but non-swirling jet. By rearranging the Navier–Stokes equations we find a single equation, in the form of a sixth-order differential operator acting on the fluctuating pressure field on the left-hand side and a series of volume and surface source terms on the right-hand side; the form of these source terms depends strongly on the presence of swirl and radial shear. The integral form of this equation is then derived, using the Green’s function tailored to the base flow in the (rigid) duct. As is often the case in duct acoustics, it is then convenient to move into temporal, axial and azimuthal Fourier space, where the Green’s function is computed numerically. This formulation can then be applied to a number of turbomachinery noise sources. For definiteness here we consider the noise produced downstream when a steady distortion flow is incident on the fan from upstream, and compare our results with those obtained using a simplistic but commonly used Doppler correction method. We show that in all but the simplest case the full inclusion of swirl within an acoustic analogy, as described in this paper, is required.

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Yang, Zhiguo, Hangfang Zhao i Wen Xu. "Bayesian passive acoustic tracking of a cooperative moving source in shallow water". IET Radar, Sonar & Navigation 8, nr 3 (marzec 2014): 202–8. http://dx.doi.org/10.1049/iet-rsn.2012.0338.

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Liang, Ningning, Yixin Yang, Xijing Guo i Boxuan Zhang. "Estimating the velocity of a moving acoustic source based on chirplet transform". Journal of the Acoustical Society of America 144, nr 3 (wrzesień 2018): 1944. http://dx.doi.org/10.1121/1.5068507.

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Buldyrev, V. S., A. V. Sokolov i A. S. Starkov. "The acoustic field of a high-frequency source moving in a waveguide". Journal of Mathematical Sciences 96, nr 4 (wrzesień 1999): 3327–31. http://dx.doi.org/10.1007/bf02172808.

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Ghorbaniasl, Ghader, Leonidas Siozos-Rousoulis i Chris Lacor. "A time-domain Kirchhoff formula for the convective acoustic wave equation". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, nr 2187 (marzec 2016): 20150689. http://dx.doi.org/10.1098/rspa.2015.0689.

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Kirchhoff’s integral method allows propagated sound to be predicted, based on the pressure and its derivatives in time and space obtained on a data surface located in the linear flow region. Kirchhoff’s formula for noise prediction from high-speed rotors and propellers suffers from the limitation of the observer located in uniform flow, thus requiring an extension to arbitrarily moving media. This paper presents a Kirchhoff formulation for moving surfaces in a uniform moving medium of arbitrary configuration. First, the convective wave equation is derived in a moving frame, based on the generalized functions theory. The Kirchhoff formula is then obtained for moving surfaces in the time domain. The formula has a similar form to the Kirchhoff formulation for moving surfaces of Farassat and Myers, with the presence of additional terms owing to the moving medium effect. The equation explicitly accounts for the influence of mean flow and angle of attack on the radiated noise. The formula is verified by analytical cases of a monopole source located in a moving medium.

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Buszman, Krystian. "Analysing the Impact on Underwater Noise of Changes to the Parameters of a Ship’s Machinery". Polish Maritime Research 27, nr 3 (1.09.2020): 176–81. http://dx.doi.org/10.2478/pomr-2020-0059.

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AbstractA ship moving over the surface of water generates disturbances that are perceived as noise, both in the air and under water. Due to its density, water is an excellent medium for transmitting acoustic waves over long distances.This article describes the impact of the settings of a ship’s machinery on the nature of the generated noise. Our analysis includes the frequency characteristics of the noise generated by the moving ship. Data were obtained using an underwater measurement system, and the measured objects were two ships moving on specific trajectories with certain machinery settings. The acquired data were analysed in the frequency domain to explore the possibilities of the acoustic classification of ships and diagnostics of source mechanisms.

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WANG, ZHAOXI, i SEAN F. WU. "RADIATED ACOUSTIC PRESSURE FROM A MOVING, NONUNIFORMLY VIBRATING CYLINDER WITH TWO SPHERICAL ENDCAPS". Journal of Computational Acoustics 02, nr 01 (marzec 1994): 71–82. http://dx.doi.org/10.1142/s0218396x94000063.

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This paper presents numerical results of radiated acoustic pressures from a moving, nonuniformly vibrating cylinder with two spherical endcaps, based on an extended Kirchhoff integral formulation. Specifically, we consider cases in which the normal component of the surface velocity is nonzero on a portion of the surface, and zero elsewhere. Numerical results demonstrate that the radiation patterns depend critically on the frequency and source dimensions. For a noncompact source, the strongest radiation may not necessarily stem from a vibrating surface, but rather from a nonvibrating surface due to the effect of sound diffraction. The more noncompact the source is, the larger the number of side lobes in the near field and the more concentrated these side lobes will be. In the far field, however, the side lobes become smeared and less distinguishable. In other words, the effect of sound diffraction is greatly reduced in the far field. Source translational motion induces sound radiation in the perpendicular direction and enhances the radiated acoustic field in general. Enhancement in the forward direction is much greater than in the reverse direction.

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Romashko, R. V., D. V. Storozhenko, M. N. Bezruk, D. A. Bobruyko i Y. N. Kulchin. "Fiber-optic vector acoustic receiver based on adaptive holographic interferometer". Laser Physics 32, nr 2 (4.01.2022): 025101. http://dx.doi.org/10.1088/1555-6611/ac44a4.

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Abstract A mobile scalar–vector acoustic receiver is proposed, experimentally implemented and investigated. The key components of the receiver are (a) the six-channel fiber-optic coil-type sensor configured as to detect three projections of acoustic intensity vector, (b) the six-channel optical phase demodulator based on six-channel adaptive holographic interferometer configured with use of dynamic holograms multiplexed in a photorefractive crystal of cadmium telluride and (c) the signals recording ADC-based system combined with software package for data processing. Field tests of the developed receiver applied for obtaining scalar and vector parameters of acoustic waves generated by a stationary and moving acoustic source in open air and water area are carried out. Experimental results show perceptiveness of use of the fiber-optical adaptive interferometry system for bearing of weak acoustic sources in real conditions.

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Cui, Hongxu, Xiaolei Li i Wei Gao. "Passive Velocity Estimation of a Distant Harmonic Source in a Pekeris Waveguide Based on Modal Doppler Shifts". Journal of Physics: Conference Series 2486, nr 1 (1.05.2023): 012071. http://dx.doi.org/10.1088/1742-6596/2486/1/012071.

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Abstract The acoustic field generated by a moving point source in terms of normal modes predicts that each mode has a different Doppler shift, i.e., modal Doppler shifts, which contains the velocity information of the moving source. This paper presents a method to estimate the velocity of a distant harmonic source in a Pekeris waveguide passively based on modal Doppler shifts. Combined with the fact that the modal depth function varies slowly with frequency, a cost function is designed to realize the velocity estimation of a distant harmonic source with a single hydrophone when the bottom parameters are unknown. The effectiveness of the method is validated by simulations.

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Li, Yongfei, Ruiming Guo, Thierry Blu i Hangfang Zhao. "Robust sparse reconstruction of attenuated acoustic field with unknown range of source". Journal of the Acoustical Society of America 152, nr 6 (grudzień 2022): 3523–34. http://dx.doi.org/10.1121/10.0016497.

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In this paper, we present a gridless algorithm to recover an attenuated acoustic field without knowing the range information of the source. This algorithm provides the joint estimation of horizontal wavenumbers, mode amplitudes, and acoustic attenuation. The key idea is to approximate the acoustic field in range as a finite sum of damped sinusoids, for which the sinusoidal parameters convey the ocean information of interest (e.g., wavenumber, attenuation, etc.). Using an efficient finite rate of innovation algorithm, an accurate recovery of the attenuated acoustic field can be achieved, even if the measurement noise is correlated and the range of the source is unknown. Moreover, the proposed method is able to perform joint recovery of multiple sensor data, which leads to a more robust field reconstruction. The data used here are acquired from a vertical line array at different depths measuring a moving source at several ranges. We demonstrate the performance of the proposed algorithm both in synthetic simulations and real shallow water evaluation cell experiment 1996 data.

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Gaunaurd, G. C., i T. J. Eisler. "Classical Electrodynamics and Acoustics: Sound Radiation by Moving Multipoles". Journal of Vibration and Acoustics 119, nr 2 (1.04.1997): 271–82. http://dx.doi.org/10.1115/1.2889714.

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In classical electrodynamics (CED) P. Dirac used the average of retarded and advanced fields to represent the bound field and their difference to represent the free field in his derivation of the (Lorentz-Dirac) equation of motion for an electron. The latter skew-symmetric combination filtered out the radiation part of the field. It can also be used to derive many properties of the power radiated by acoustic sources, such as angular and frequency distributions. As in CED there is radiation due to source acceleration and radiation patterns exhibit the “headlight effect.” Power radiation patterns are obtained by this approach for point multipoles undergoing various motions. Applications to sound radiation problems from rotating machinery are shown. Numerous computed plots illustrate all cases.

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Eastland, Grant. "Finite difference time domain ray-based modelling of acoustic scattering for target identification and tracking". Journal of the Acoustical Society of America 152, nr 4 (październik 2022): A252. http://dx.doi.org/10.1121/10.0016182.

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The Finite Difference Time Domain (FDTD) method has provided a powerful technique for modelling and simulation of solutions of a variety of acoustics problems. The purpose of this investigation is to present work on the development of time-domain models of acoustic scattering from targets near a flat pressure-release boundary for use in identification and tracking from a moving receiving platform. The timing from acoustic source to reception are dependent on the location dependent sound speed profile and the specular scattering points on the target. There can be multiple specular points revealed on the target because of interactions with the flat boundary; each of which are modelled utilizing the FDTD method providing path corrections due to variation in propagation brought on by the sound speed profile of the environment.

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CHOO, YOUNGMIN, i WOOJAE SEONG. "MODELING AND ANALYSIS OF AN ACOUSTIC CHANNEL WITH A MOVING SURFACE". Journal of Computational Acoustics 21, nr 04 (grudzień 2013): 1350015. http://dx.doi.org/10.1142/s0218396x1350015x.

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A ray tracing algorithm for moving surfaces is derived to enable the analysis of surface movement effects. For this, a ray tracing algorithm for frozen surface is modified. By comparing the results from frozen and moving surface ray models allows effects of a moving surface to be investigated. The surface movement effects can be seen with the difference between channel impulse responses from the frozen and moving surface ray models. For an investigation of ray path dependence of the surface movement effects, delay times of surface reflective paths from the two ray models are observed according to transmitted ping time. As the ray path from the source to surface gets longer, difference of travel time results from the two ray models increase. This fact indicates that surface movement effects depend on ray path, in particular travel time until a ray meets a surface.

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van Ophem, Sjoerd, i Wim Desmet. "A reduced-order cutFEM approach to model complex moving sound sources". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, nr 4 (1.02.2023): 3763–70. http://dx.doi.org/10.3397/in_2022_0531.

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While traditional finite element based vibro-acoustic analysis of structures is done on stationary structures, in many occasions the structure under investigation is actually moving. To perform accurate finite element analysis on the vibro-acoustic performance of such structures requires the evaluation of a time-varying system, leading to several challenges. Of paramount importance are a strategy to update the mesh to the new configuration and an adequate time integration scheme that does not introduce large numerical artifacts. Additionally, the time-varying nature leads to an increase in computational complexity. In this paper a modeling strategy based on cut finite elements (cutFEM) is introduced that aims to tackle these challenges. The cutFEM approach can be seen as a fictitious domain approach in which the source is moving over a static mesh, cutting through elements where the actual source is located, using a level set description. The key advantage of this approach is that no remeshing and/or mesh morphing is required. It is shown how both implicit and explicit time integration schemes can be used to propagate the solution while the source is moving. Additionally, several model order reduction strategies are compared to speed up the online evaluation of the reduced order model.

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Guan, Yiheng, i Dan Zhao. "Theoretical investigation on the moving flame–sound interaction in a closed-open combustor". Journal of the Acoustical Society of America 153, nr 3_supplement (1.03.2023): A283. http://dx.doi.org/10.1121/10.0018855.

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Self-excited thermoacoustic instability is highly undesirable for power generation gas turbines, aero-engine afterburners, liquid-fuelled ramjet, and rocket motors. It is typically generated due to the constructive interaction between acoustic perturbations and the flame. It is a general practice to assume that the flame is non-moving and the combustor is typically assumed to be acoustically opened. In this work, we consider a closed-open thermoacoustic combustor with a moving flame. To better understand the physics between the acoustic disturbances and the moving flame, we theoretically investigate the moving flame-sound interaction. We find that the presence of the moving flame can amplitude the gaseous oscillations. Furthermore, the amplification process is shown to depend on the laminar burning velocity on the temperature and density of the combustible gas mixture into which the flame propagates. The sound source is shown to be the quadrupole mode. It radiates very little energy, if the flame dimensions are smaller than the wavelength of the sound produced. The present work shed lights on the sound generation from a moving flame and its interaction with sound.

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Moran, M. L., i R. J. Greenfield. "Estimation of the Acoustic-to-Seismic Coupling Ratio Using a Moving Vehicle Source". IEEE Transactions on Geoscience and Remote Sensing 46, nr 7 (lipiec 2008): 2038–43. http://dx.doi.org/10.1109/tgrs.2007.910712.

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