Dissertations / Theses on the topic 'Acoustic source identification'
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Sasidharan, Nair Unnikrishnan. "Jet noise source localization and identification." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1482412964456451.
Full textFacciotto, Nicolò. "Source differentiation and identification of acoustic emission signals by time-frequency analysis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textChesnais, Corentin. "Holographie vibratoire : Identification et séparation de champs vibratoires." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI127/document.
Full textThe source field reconstruction aims at identifying the excitation field measuring the response of the system. In Near-field Acoustic Holography, the response of the system (the radiated acoustic pressure) is measured on a hologram using a microphones array and the source field (the acoustic velocity field) is reconstructed with a back-propagation technique performed in the wave number domain. The objective of the present works is to use such a technique to reconstruct displacement field on the whole surface of a plate by measuring vibrations on a one-dimensional holograms. This task is much more difficult in the vibratory domain because of the complexity of the equation of motion of the structure. The method presented here and called "Structural Holography" is particularly interesting when a direct measurement of the velocity field is not possible. Moreover, Structural Holography decreases the number of measurements required to reconstruct the displacement field of the entire plate. This method permits to separate the sources in the case of multi-sources excitations by considering them as direct or back waves. It’s possible to compute the structural intensity of one particular source without the contributions of others sources. The aim of this PHD is to present the principles of Structural Holography, its limits, its applications and illustrate them with examples of infinite plate, supported plate and on experimental results
Wu, Weiliang. "The detection of incipient faults in small multi-cylinder diesel engines using multiple acoustic emission sensors." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/65649/1/Weiliang_Wu_Thesis.pdf.
Full textLe, Magueresse Thibaut. "Approche unifiée multidimensionnelle du problème d'identification acoustique inverse." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI010.
Full textExperimental characterization of acoustic sources is one of the essential steps for reducing noise produced by industrial machinery. The aim of the thesis is to develop a complete procedure to localize and quantify both stationary and non-stationary sound sources radiating on a surface mesh by the back-propagation of a pressure field measured by a microphone array. The inverse problem is difficult to solve because it is generally ill-conditioned and subject to many sources of error. In this context, it is crucial to rely on a realistic description of the direct sound propagation model. In the frequency domain, the equivalent source method has been adapted to the acoustic imaging problem in order to estimate the transfer functions between the source and the antenna, taking into account the wave scattering. In the time domain, the propagation is modeled as a convolution product between the source and an impulse response described in the time-wavenumber domain. It seemed appropriate to use a Bayesian approach to use all the available knowledge about sources to solve this problem. A priori information available about the acoustic sources have been equated and it has been shown that taking into account their spatial sparsity or their omnidirectional radiation could significantly improve the results. In the assumptions made, the inverse problem solution is written in the regularized Tikhonov form. The regularization parameter has been estimated by an empirical Bayesian approach. Its superiority over methods commonly used in the literature has been demonstrated through numerical and experimental studies. In the presence of high variability of the signal to noise ratio over time, it has been shown that it is necessary to update its value to obtain a satisfactory solution. Finally, the introduction of a missing variable to the problem reflecting the partial ignorance of the propagation model could improve, under certain conditions, the estimation of the complex amplitude of the sources in the presence of model errors. The proposed developments have been applied to the estimation of the sound power emitted by an automotive power train using the Bayesian focusing method in the framework of the Ecobex project. The cyclo-stationary acoustic field generated by a fan motor was finally analyzed by the real-time near-field acoustic holography method
Li, Lin. "Identification des sources acoustiques induites par les singularites d'un circuit hydraulique." Paris 6, 1988. http://www.theses.fr/1988PA066366.
Full textFischer, Jeoffrey. "Identification de sources aéroacoustiques au voisinage de corps non profilés par formation de voies fréquentielle et temporelle." Thesis, Poitiers, 2014. http://theses.univ-poitiers.fr/62768/2014-Fischer-Jeoffrey-These.
Full textThe localization of aeroacoustic sources of automotive bodies is currently a topic of major interest to industry. Beamforming is a robust method typically used in this context. The main objective of this thesis relates to the detection of aeroacoustic sources on bluff bodies. Two experimental configurations are considered : a forwardfacing step that is an academic event, and a three dimensional bluff body generating A-pillar vortices approaching the automotive industry. Source localization through classical beamforming has enabled to detect the main regions of acoustic emission for different frequency ranges, namely : upstream and downstream vortices around thestep and A-pillar vortices generated on both sides of the 3D bluff body. In addition, relationships have been observed between wall pressure fluctuations and acoustic field radiated. The study was then directed to the detection of intermittent acoustic events to determine whether, like jet noise, the noise radiated by an obstacle in the flow is composed of intermittent signatures. A thresholding process on the far field measurements was used to select events representing 80% of the energy of the original signal and 20% of its time for both configurations. A time-domain beamforming algorithm, directly linked to the time reversal technique, has been developed to achieve a spatio-temporal information about the intermittent noise sources. The use of this technique has proved that the events selected with the tresholding technique correspond to intermittent acoustic sources which space and time informations canbe determined (they follow a Gamma distribution). The aeroacoustic noise radiated by the bluff bodies considered in this study can therefore be seen as a succession of intermittent events that can be identified. Finally, the reconstruction of intermittent acoustic signals using a family of wavelets was performed. The Fourier spectra of the original and reconstructed signals are highly similar, a difference of about 10% was observed, confirming the importance of intermittent events in the noise radiated by bluff bodies
Halama, Jakub. "Metodika pro bezkontaktní diagnostiku automobilových tlumičů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-377521.
Full textSamet, Ahmed. "Contribution à l'identification des sources vibratoires et à la détection des défauts par approche énergétique." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC055/document.
Full textThe identification of inputs forces acting on structures and the detection of defects from operating measurement have been important topics in both academic and industrial projects. The choice of the used tool or method depends on the frequency band of study since there are appropriate approaches for each frequency domain. An energetic method so called the simplified energy method (MES) is used to predict the distribution of the vibro-acoustic energy density in the medium and high frequency band. The objective of this thesis is to extend this energy method to solve inverse vibro-acoustic problems and to identify the sources of vibrations on one hand and to detect the defects on the other hand. The inverse MES formulation (IMES) is numerically validated for continuous coupling-based systems such as the case of a system composed with several coupled plates and the case of a system composed of an acoustic cavity coupled with a plate. In addition, a new numerical methodology is proposed to extend this IMES identification tool for the detection of defects. A parametric analysis is performed in the case of plate with defects in order to test the robustness and the efficiency of this approach. Finally, an experimental study is carried out to validate the IMES technique to identify and locate the input loads for several scenarios, and detecting the defects
Cabell, Randolph H. "The automatic identification of aerospace acoustic sources." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/45932.
Full textThis work describes the design of an intelligent recognition system used to distinguish noise signatures of five different acoustic sources. The system uses pattern recognition techniques to identify the information obtained from a single microphone. A training phase is used in which the system learns to distinguish the sources and automatically selects features for optimal performance. Results were obtained by training the system to distinguish jet planes, propeller planes, a helicopter, train, and wind turbine from one another, then presenting similar sources to the system and recording the number of errors. These results indicate the system can successfully identify the trained sources based on acoustic information. Classification errors highlight the impact of the training sources on the system's ability to recognize different sources.
Master of Science
Tan, Jin Jack. "Piano acoustics : string’s double polarisation and piano source identification." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLY014/document.
Full textThe objective of this thesis is to improve the understanding of the acoustics of the piano in the context of physically-based sound synthesis. The manuscript is decomposed in three parts, the first two being devoted to the undertsanding of the origin of the double polarisation in piano string, while the third one is dedicated to the identification of sound sources of a complete piano.In the first part, the geometric (large-amplitude) nonlinearity is studied in order to understand if the nonlinear coupling can transfer energy to an initially non excited polarisation, thus leading to the double polarisation phenomenon. A multiple-scaleanalysis is conducted on a Kirchhoff-Carrier string model with fixed boundary conditions at both ends. Each polarisation is restrained to its fundamental mode, leading to two oscillors having nearly equal eigenfrequencies, and thus presenting a 1:1 internal resonance. The existence condition and stability criteria for double polarisation to occur are obtained and validated numerically based on the complete Kirchhoff-Carrier equations, as well as a more enriched third-order string model. Experiments are carried out on a monochord setup where the natural polarisation angles of the string, detuning between the two polarisations and its nonlinear behaviour are observed and identified.The second part is devoted to the string/bridge coupling. The degrees of freedom of the string are coupled to the bridge whose translational and rotational motions are respresented by a set of oscillators. The eigenfrequencies of various coupled systems are analysed. Numerical schemes are proposed and implemented where the string is solved via high-order finite-element method while the lumped bridge is solved analytically and coupled to the string by Lagrange multipliers. Experimentally, the string is strung over a bridge in a zig-zag configuration and excited vertically and horizontally. In both cases, double polarisation and double decay are observed and similar results are also obtained qualitatively in numerical models.The last part is devoted to a quantitative description of the vibroacoustic sources of a Bösendorfer 280VC-9 piano via operational transfer path analysis. The contribution of the soundboard, inner and outer rim, iron frame and lid are investigated in the frequency domain. It is found out that the soundboard is the primary contributor but the iron frame and the lid also play a significant role, especially at high frequencies
Baron, Valentin. "Méthodes d’identification de sources acoustiques paramétriques par mesures d’antennerie." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI121.
Full textAcoustic sources characterization aims to describe sound emitters through some parameters like their localization in space, the sound level they produce or their identification thanks to their acoustic signature. In this thesis, the objective is to obtain some of these parameters in two industrial application cases, for sources located in far-field and by the use of acoustic arrays. The first application concerns deep-sea mining acoustic impact in the context of Abysound FUI project. Within it, the thesis searches to characterize the excavation machine located on the seabed by assessing their localization and their sound level. First, a design phase has led to the construction of a 3 m size acoustic array. Then, using data from two experimental campaigns conducted in the Mediterranean Sea with this array, the high-resolution method MUSIC accurately localizes the used acoustic sources, either mobile and more than 600 m away from the array, or immersed by 700 m depth. Their sound level is then estimated by beamforming, and the expected levels are verified for monochromatic or wideband signals. In the second application, a complete procedure for the localization and the identification of drones is proposed to protect sensitive areas. It combines array processing and machine learning through three key steps: localization, focalization, and identification. MUSIC localizes again nearby acoustic sources around the industrial array used, then focalization reconstructs each temporal signal, and a SVM model identifies them as drone or not. Experimental validations, inside and outside, establish an important contribution of this thesis work. Acquired data show for instance that the procedure localizes drones with 3° accuracy outside, detects them at 99 %, or identifies them despite the presence of a more powerful source
Demontis, Hugo. "Identification de sources acoustiques complexes en milieu réverbérant par grands réseaux de microphones." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS196.
Full textKnowing the directivity pattern of an acoustic source is useful in many applications in acoustics. To experimentally estimate the spatial signature, it is common to deploy microphones partially or totally surrounding the source. The acoustic radiation is then captured in all possible directions. In this thesis, we discuss the development of a large-scale 3D microphone array. This array, named "MODO" ("Les Murs Ont Des Oreilles", or, "The Walls Have Ears"), is comprised of 1024 digital MEMS microphones, flush mounted on the walls and the ceiling of a typical shoe-box room. In order to localize the sources and identify their directivity pattern, we solve the associated inverse problem under block-sparsity constraints. The chosen method exploits the small number of sources inside the room, allowing a sparse representation of the measured sound field. We use the spherical harmonics formalism to efficiently describe the directivity of the sources and their individual contributions to the radiation pattern. The acoustic path is modelled via integration of room transfer functions, synthesized with the mirror microphone method. We validated the proposed characterization method \textit{in situ} by comparison with known directivity patterns, calibrated using a high order spherical microphone array in controlled conditions
Abdou, Wael Saber Soliman. "Identification of acoustic emission sources in machinery : application to injection/combustion processes in diesel engines." Thesis, Heriot-Watt University, 2015. http://hdl.handle.net/10399/2979.
Full textCousson, Rémi. "Identification de sources acoustiques au passage d'un véhicule routier par imagerie acoustique parcimonieuse dans le domaine temporel." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI106/document.
Full textThe study detailed in this manuscript is part of the effort to characterize the noise emission from road vehicles. We wish to identify the noise sources of a moving vehicle, when driven on a roadway in real-world conditions, with roadside acoustic measurements. The current acoustic imaging methods do not provide sufficient performance on road vehicles. A state of the art led to the selection of an existing method, MSA-PSF, which consists in deconvolving signals from mobile sources in the frequency domain under certain assumptions, and was originally developed for aeroacoustics. This method is adapted here to the context of road vehicles. Then, an original approach is proposed in order to tackle the specific constraints of this context: CLEANT. This is an iterative method, performed in time domain with a wideband approach, which takes into account the effect of sources motion and includes two parameters designed to refine the result: the loop factor and the stopping criterium. A further version of the algorithm, including a frequency filter, is also proposed and shows significant improvement in identifying secondary sources in some particular cases. An interesting point of CLEANT is the availability of the sources reconstructed time signals, which enables other types of analysis, especially the use of the coherence with signals from on-board measurements in order to separate the contributions of uncorrelated sources. MSA-PSF and CLEANT are evaluated with numerical simulations and a set of indicators to measure their source localization and quantification performance. They are then tested in a controlled laboratory conditions experiment, using a moving source. This experiment represents a first application of the methods to a practical case, involving a linear motion, two simultaneous sources and different kinds of signals (tone and wideband). They are finally compared to the classical approach of moving source beamforming, within the frame of an experiment on a road vehicle, in real-world conditions. The original approach CLEANT yields very encouraging results, and is a clear improvement from the conventional beamforming, especially at low frequency for the tested cases. Applying it to a road vehicle in real-world conditions highlights a potentially troublesome behavior of the method, and the solution brought by CLEANT's frequency filtered version, or by adapting its various parameters. The coherence with reference signals to discriminate the physical origins of the sources is also tested and underlines the role of the short duration of the signals related to the sources passing-by context
Tas, Idir. "Traitement d'antenne passif : détection et identification de sources." Grenoble INPG, 1987. http://www.theses.fr/1987INPG0076.
Full textRenzi, Cédric. "Identification Expérimentale de Sources vibratoires par Résolution du problème Inverse modélisé par un opérateur Eléments Finis local." Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00715820.
Full textSanalatii, Maryna. "Synthèse d'un champ acoustique avec contraste spatial élevé." Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1005/document.
Full textThe goal of this thesis is the design of a transportable speaker system, able to generate a predefined and focused sound field with a high spatial contrast. This system has eventually to allow carrying out different types of studies, for example acoustic transmission loss tests or vibration tests in non-anechoic conditions. The minimization of the number of driven channels and the number of transducers is one of the main goals of the work. The choice of the number of sources and the selection of their optimal positions in order to generate a target acoustic field has no trivial solution. To answer this question, the proposed method is based on the decomposition of the source radiation into a series of independent orthogonal functions (the "radiation modes"), constructed numerically via a singular value decomposition of the impedance matrix. By filtering the evanescent terms, the far field can be reconstructed using a small number of terms. In addition, the method allows the estimation of an efficient flow distribution to generate the target field. With the proposed method having been scarcely studied in the literature, the first part of the thesis is devoted to the problem of the experimental validation of the direct method and the study of the main parameters that are influencing the result. The problem of sources positioning in order to synthesize a predefined and focused sound field is discussed in the second part of the thesis
Pereira, Antonio. "Imagerie acoustique en espace clos." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00984347.
Full textDefreville, Boris. "CARACTÉRISATION DE LA QUALITÉ SONORE DE L'ENVIRONNEMENT URBAIN : UNE APPROCHE PHYSIQUE ET PERCEPTIVE BASÉE SUR L'IDENTIFICATION DES SOURCES SONORES." Phd thesis, Université de Cergy Pontoise, 2005. http://tel.archives-ouvertes.fr/tel-00011453.
Full textLa première partie met en évidence le fait que celles-ci ne sont pas toutes perçues de la même manière et qu'en conséquence leurs évaluations métrologiques doivent être adaptées. Ce travail permet de proposer un indicateur lié au désagrément sonore ; en fonction du lieu, cet indicateur utilise la force sonore de la séquence, mais il prend toujours en compte les caractéristiques des différentes sources émergentes.
La deuxième partie de l'étude propose deux méthodes pour la mesure automatique de cet indicateur à travers l'identification des sources. Ces outils représentent, in fine, une aide à la gestion d'un environnement sonore de quartier.
chuan, wang chih, and 王志全. "Near-field Acoustic Holography for Noise Source Identification." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/31414326927406532345.
Full text國立海洋大學
系統工程暨造船學系
90
In this thesis, the acoustic field data is measured on a two dimensional microphones array close to the noise source. By spatial transformation, three dimensional space sound field data, such as near-field sound pressure, near-field sound intensity, far-field sound pressure, and far-field sound intensity can be calculated, with “Acoustic Holography Analysis” of Lms’ software “Cada-x”. First, in order to make sure that all experimentation collocate software are practicable, and the application in structure noise source identification. Therefore the experiment process is step by step generally, then the location, intensity, and distribution property of noise source will be proved and discussed. This thesis divide into three parts:(1) A stationary single sound source in the anechoic room:use a isotropic speaker, and a fan of computer for the provement in source distribution location. (2) Stationary multiple sound sources in the anechoic room:identify the location of noise sources by isotropic speaker and plane speaker. (3) The tires of the car:The acoustic radiation from the tire surface can be predicted by using sharker;Besides, the distribution property of the noise sources on the tire surface can be identify by operating the tires in the roller belt. For all study results show, Acoustic Holography identify noise sources are quite correct. Therefore noise source identification dimension, it is very effective ways.
Lee, Jihwang, and 李枝煌. "INDUSTRIAL NOISE SOURCE IDENTIFICATION BY USING AN ACOUSTIC BEAMFORMING SYSTEM." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/10033446958835363832.
Full textWang, Shao-Wei, and 王少微. "Acoustic Camera for Analysis and Identification of Compound Noise Sources." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/m89sxt.
Full text國立臺灣海洋大學
系統工程暨造船學系
105
In this thesis, the acoustic camera is used in the case of compound noise sources.It calculates the sound pressure and spectrum base on beamforming theory. The result of the calculation will show on the screen in different colors to indicate the position of the sound source. In the experiment, two reference sound sources, which have similar acoustic power, is used to simulate the phenomenon of compound noise sources. Comparing the pressure and the spectrum of the computational sound source with the reference sound source, the result indicated that they have similar spectrum. And also, the software is able to calculate the sound pressure in the different distance by using feedback mechanism. At last, applying acoustic camera to compound noise sources, the position of either the reflected sound component or the abnormal sound can be easily identified.