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Littérature scientifique sur le sujet « Acoustic tile »

Auteur : Grafiati

Publié le 4 juin 2021

Mis à jour le 9 février 2022

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Articles de revues sur le sujet "Acoustic tile"

Schuelke, David J., Randy H. Barnard et Kenneth E. Kleinke. « Acoustic tile ». Journal of the Acoustical Society of America 87, n^o 1 (janvier 1990) : 466. http://dx.doi.org/10.1121/1.399255.

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Boerckel, David A., et Lawrence H. Boerckel. « Acoustic tile cutting assembly ». Journal of the Acoustical Society of America 84, n^o 4 (octobre 1988) : 1579. http://dx.doi.org/10.1121/1.397199.

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Grygorowicz-Kosakowska, Klaudia, et Anna Sygulska. « The Acoustic Ceramic Module ». Leonardo 53, n^o 3 (mai 2020) : 268–73. http://dx.doi.org/10.1162/leon_a_01742.

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This paper discusses issues common to architecture, sculpture and acoustics and presents the authors' design of an acoustic ceramic module, currently in the prototype stage. The project was conceived to create a system of ceramic tiles that can create a space as well as enhance the acoustics of its interior. Modularity ensures that through numerous combinations many patterns can be produced from one tile design. The ceramic materials used may vary, from porous chamotte to the smooth surfaces of casting slips to glazing. The key issue, apart from shaping an interior architecture, was to focus on the acoustic function of the tiles. The creative process was of a two-fold nature: Its visual aspect focused on individualization of the space, while its functional one was to ensure acoustically comfortable interiors.

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Corsaro, Robert. « Thin, lightweight acoustic actuator tile ». Journal of the Acoustical Society of America 117, n^o 3 (2005) : 990. http://dx.doi.org/10.1121/1.1896647.

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Topolář, Libor, Dalibor Kocáb, Jiří Šlanhof, Pavel Schmid, Petr Daněk et Jaroslav Nováček. « Testing the Influence of the Material Bonding System on the Bond Strength of Large-Format Tiles Installed on Concrete Substrate under Mechanical Loading ». Materials 13, n^o 14 (17 juillet 2020) : 3200. http://dx.doi.org/10.3390/ma13143200.

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The paper describes an experiment focusing on the way the material system influences the bond strength of large-format tiles installed on concrete substrate during mechanical loading under conditions that correspond to real-life application. This involves a controllable mechanical load applied over an area of a test model while observing its condition using non-destructive methods (ultrasonic pulse velocity test, acoustic emission method, strain measurement, and acoustic tracing). The model consisted of a concrete slab onto which were mounted four different systems with large-format tiles with the dimensions of 3 m × 1 m. The combinations differed in the thickness of the tile, the adhesive, and whether or not a fabric membrane was included in the adhesive bed. The experiment showed that the loading caused no damage to the ceramic tile. All the detected failures took place in the adhesive layer or in the concrete slab.

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Mueller, S. A., et F. A. Moslehy. « An Inverse Vibration Method Applied to Bond Evaluation of Space Shuttle Tiles ». Journal of Vibration and Acoustics 118, n^o 3 (1 juillet 1996) : 454–62. http://dx.doi.org/10.1115/1.2888205.

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This paper describes an inverse vibration method for determining unknown parameters of the physical system by using partial modal information. The method is based on knowing the complete mass matrix of the system and part of its stiffness matrix. The unknown parameters in the stiffness matrix are related to the physical system. This method is applied to the bond evaluation of the space shuttle tiles. The tiles are excited by audible acoustic energy and the response is measured by a noncontact laser vibrometer. The inverse solution is incorporated into a user-friendly computer program to determine the size and location of disbonded regions in the tile assembly. The program allows for any tile geometry as well as the orthotropic properties of the the material. Both simulated data, provided by finite element analysis, and experimentally acquired data are used to verify the proposed method.

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Kilcullen, Patrick, Mark Shegelski, MengXing Na, David Purschke, Frank Hegmann et Matthew Reid. « Terahertz Spectroscopy and Brewster Angle Reflection Imaging of Acoustic Tiles ». Journal of Spectroscopy 2017 (2017) : 1–6. http://dx.doi.org/10.1155/2017/2134868.

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A Brewster angle reflection imaging apparatus is demonstrated which is capable of detecting hidden water-filled voids in a rubber tile sample. This imaging application simulates a real-world hull inspection problem for Royal Canadian Navy Victoria-class submarines. The tile samples represent a challenging imaging application due to their large refractive index and absorption coefficient. With a rubber transmission window at approximately 80 GHz, terahertz (THz) sensing methods have shown promise for probing these structures in the laboratory. Operating at Brewster’s angle allows for the typically strong front surface reflection to be minimized while also conveniently making the method insensitive to air-filled voids. Using a broadband THz time-domain waveform imaging system (THz-TDS), we demonstrate satisfactory imaging and detection of water-filled voids without complicated signal processing. Optical properties of the tile samples at low THz frequencies are also reported.

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Xie, Luofeng, Ming Yin, Qinyuan Huang, Yue Zhao, Zhenbo Deng, Zhaowei Xiang et Guofu Yin. « Internal defect inspection in magnetic tile by using acoustic resonance technology ». Journal of Sound and Vibration 383 (novembre 2016) : 108–23. http://dx.doi.org/10.1016/j.jsv.2016.07.020.

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Mueller, Donald S. « LOW DENSITY NON-WOVEN MATERIAL USEFUL WITH ACOUSTIC CEILING TILE PRODUCTS ». Journal of the Acoustical Society of America 131, n^o 5 (2012) : 4226. http://dx.doi.org/10.1121/1.4712251.

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Yao, W., Z. Li et M. Qi. « Damage process detection of a ceramic tile system by acoustic emission ». Experimental Mechanics 40, n^o 3 (septembre 2000) : 265–70. http://dx.doi.org/10.1007/bf02327499.

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Thèses sur le sujet "Acoustic tile"

Liddy, David W. Holmes John F. « Acoustic room de-reverberation using time-reversal acoustics / ». Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA374579.

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Thesis (M.S. in Applied Physics) Naval Postgraduate School, September 1999.
"September 1999". Thesis advisor(s):, Andrés Larraza, Bruce C. Denardo. Includes bibliographical references (p. 49). Also available online.

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Liddy, David W., et John F. Holmes. « Acoustic room de-reverberation using time-reversal acoustics ». Thesis, Monterey, California : Naval Postgraduate School, 1999. http://hdl.handle.net/10945/13698.

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This thesis probes the performance of one-channel time-reversal acoustics in a chamber in terms of the geometry of the cavity. In particular, a rectangular chamber is compared to an enclosure that has a stadium shape. The mode structure in the rectangular cavity is highly symmetric, while it is highly irregular in the stadium-shaped cavity. Time- reversal acoustic techniques produce an improved focus in the latter. The focusing quality is determined as a function of frequency, time-reversal window size, and spatial extent. A scheme for encrypted acoustic communication, both in air and underwater, that uses multiple broadband signals with identical bandwidth, Hanning window source spectra, and center frequencies separated by half the bandwidth, allowing for null detection between adjacent signals, is successfully investigated.

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Ajaz, Mahnoor. « Finite Difference Time Domain Modelling of Ultrasonic Parametric Arrays in Two-Dimensional Spaces ». The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619109761801613.

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Fabre, Josette. « Representative Environments for Reduced Estimation Time of Wide Area Acoustic Performance ». ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1156.

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Advances in ocean modeling (Barron et al., 2006) have improved such that ocean forecasts and even ensembles (e.g., Coelho et al., 2009) representing ocean uncertainty are becoming more widely available. This facilitates nowcasts (current time ocean fields / analyses) and forecasts (predicted ocean fields) of acoustic propagation conditions in the ocean which can greatly improve the planning of acoustic experiments. Modeling of acoustic transmission loss (TL) provides information about how the environment impacts acoustic performance for various systems and system configurations of interest. It is, however, very time consuming to compute acoustic propagation to and from many potential source and receiver locations for multiple locations on an area-wide grid for multiple analysis / forecast times, ensembles and scenarios of interest. Currently, to make such wide area predictions, an area is gridded and acoustic predictions for multiple directions (or radials) at each grid point for a single time period or ensemble, are computed to estimate performance on the grid. This grid generally does not consider the environment and can neglect important environmental acoustic features or can overcompute in areas of environmental acoustic isotropy. This effort develops two methods to pre-examine the area and time frame in terms of the environmental acoustics in order to prescribe an environmentally optimized computational grid that takes advantage of environmental-acoustic similarities and differences to characterize an area, time frame and ensemble with fewer acoustic model predictions and thus less computation time. Such improvement allows for a more thorough characterization of the time frame and area of interest. The first method is based on critical factors in the environment that typically indicate acoustic response, and the second method is based on a more robust full waveguide mode-based description of the environment. Results are shown for the critical factors method and show that this proves to be a viable solution for most cases studied. Limitations are at areas of high loss, which may not be of concern for exercise planning. The mode-based method is developed for range independent environments and shows significant promise for future development.

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Root, Joseph Andrew. « Capabilities of an underwater acoustic volumetric array using time-reversal ». Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/18944.

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Anderson, Shaun David. « Time-frequency methods for the analysis of multistatic acoustic scattering of elastic shells in shallow water ». Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39640.

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The development of low-frequency sonar systems, using for instance a network of autonomous systems in unmanned vehicles, provides a practical means for bistatic measurements (i.e. when the source and receiver are widely separated) allowing for multiple viewpoints of the target of interest. Time-frequency analysis, in particular Wigner-Ville analysis, takes advantage of the evolution time dependent aspect of the echo spectrum to differentiate a man-made target (e.g. elastic spherical shell) from a natural one of the similar shape (e.g. solid). A key energetic feature of fluid loaded and thin spherical shell is the coincidence pattern, or mid-frequency enhancement echoes (MFE), that result from antisymmetric Lamb-waves propagating around the circumference of the shell. This thesis investigates numerically the bistatic variations of the MFE (with respect to the monostatic configuration) using the Wigner-Ville analysis. The observed time-frequency shifts of the MFE are modeled using a previously derived quantitative ray theory for spherical shell's scattering. Additionally, the advantage of an optimal array beamformer, based on joint time delays and frequency shifts (over a conventional time-delay beamformer) is illustrated for enhancing the detection of the MFE recorded across a bistatic receiver array.

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Bajer, Tomáš. « Problematika využití surovin na bázi skelných recyklátů ». Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371894.

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Presented work deals with the problem of solar glass waste recycling. In theoretical part recent EU regulation regarding waste management is presented. Different ways of PV panels recycling are explained as well as raw materials for glass production are listed. Differences between regular and solar glass is explained. In experimental part different recipes using solar glass waste and polymer binders are presented. Grindability was tested on specimen tiles. Potential of solar glass waste for manufacturing products with acoustic properties was examined.

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Kokolia, Jakub. « Senior park ». Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226408.

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The master’s thesis project is developed for the implementation of a new building for the elderly and persons with reduced mobility - Senior Park. The building is divided into several parts: the main building with facilities and separate wooden houses for the accommodation. The main building is a single-storey structure with a vegetative roof. The houses are designed with gable roof, without a basement. There is an emphasis on utmost privacy of individuals along with the care and closeness to nature. I embedded the main building partially into the ground so as to offset the difference in land and thus facilitate the movement after the plot and also served as a park for the inhabitants.

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Anderson, Shaun David. « Space-time-frequency processing from the analysis of bistatic scattering for simple underwater targets ». Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45771.

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The development of low-frequency SONAR systems, using a network of autonomous systems in unmanned vehicles, provides a practical means for bistatic measurements (i.e. when the source and receiver are widely separated, thus allowing multiple viewpoints of a target). Furthermore, time-frequency analysis, in particular Wigner-Ville analysis, takes advantage of the evolution of the time dependent echo spectrum to differentiate a man-made target (e.g. an elastic spherical shell, or cylinder) from a natural one of the similar shape (e.g. a rock). Indeed, key energetic features of man-made objects can aid in identification and classification in the presence of clutter and noise. For example, in a fluid-loaded thin spherical shell, an energetic feature is the mid-frequency enhancement echoes (MFE) that result from antisymmetric Lamb waves propagating around the circumference of the shell, which have been shown to be an acoustic feature useful in this pursuit. This research investigates the enhancement and benefits of bistatic measurements using the Wigner-Ville analysis along with acoustic imaging methods. Additionally, the advantage of joint space-time-frequency coherent processing is investigated for optimal array processing to enhance the detection of non-stationary signals across an array. The proposed methodology is tested using both numerical simulations and experimental data for spherical shells and solid cylinders. This research was conducted as part of the Shallow Water Autonomous Mine Sensing Initiative (SWAMSI) sponsored by ONR.

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Edelmann, Geoffrey F. « Underwater acoustic communications using time reversal / ». Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2003. http://wwwlib.umi.com/cr/ucsd/fullcit?p3099539.

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Livres sur le sujet "Acoustic tile"

Gan, Woon Siong. Time Reversal Acoustics. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-3235-8.

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Brown, Lee A. Real time nearfield acoustic holography. Leicester : De Montfort University, 1998.

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Carocho, Antonio J. Acoustic impedance of materials from reverberation time. Monterey, Calif : Naval Postgraduate School, 1991.

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Chaulk, Edwin K. Arrival time tracking of partially resolved acoustic rays with application to ocean acoustic tomography. Monterey, Calif : Naval Postgraduate School, 1991.

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Schobben, Daniel W. E. Real-time Adaptive Concepts in Acoustics. Dordrecht : Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0812-9.

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Fernandes, B. T. Multiphase acoustic computer-based real-time displacement measuring system. Manchester : UMIST, 1995.

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Chi, Cheng. Underwater Real-Time 3D Acoustical Imaging. Singapore : Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-3744-4.

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Crocker, Steven Edward. Time domain modal beamforming for a near vertical acoustic array. Monterey, Calif : Naval Postgraduate School, 1991.

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Ziomek, Lawrence J. Fundamentals of acoustic field theory and space-time signal processing. Boca Raton : CRC Press, 1995.

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Watson, Willie Ross. A time domain numerical theory for studying steady-state acoustic disturbances in flow. [S.l.] : George Washington University, 1991.

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Chapitres de livres sur le sujet "Acoustic tile"

Brind, R. J. « Scattering of an Acoustic Wave by a Transmission-Loss Tile ». Dans Progress in Underwater Acoustics, 145–51. Boston, MA : Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-1871-2_18.

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Al-Harthi, Noha, Rabab Alomairy, Kadir Akbudak, Rui Chen, Hatem Ltaief, Hakan Bagci et David Keyes. « Solving Acoustic Boundary Integral Equations Using High Performance Tile Low-Rank LU Factorization ». Dans Lecture Notes in Computer Science, 209–29. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-50743-5_11.

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Gan, Woon Siong. « Application of Acoustic Metamaterial to Time-Reversal Acoustics ». Dans New Acoustics Based on Metamaterials, 243–57. Singapore : Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-6376-3_9.

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Gooch, Jan W. « Acoustical Tile ». Dans Encyclopedic Dictionary of Polymers, 13. New York, NY : Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_170.

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Fink, Mathias, Fabrice Lemoult, Julien de Rosny, Arnaud Tourin et Geoffroy Lerosey. « Subwavelength Focussing in Metamaterials Using Far Field Time Reversal ». Dans Acoustic Metamaterials, 141–68. Dordrecht : Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-4813-2_6.

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Gan, Woon Siong. « Lie Group and Lie Algebra ». Dans Time Reversal Acoustics, 7–13. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-3235-8_2.

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Gan, Woon Siong. « Onsager Reciprocal Relations ». Dans Time Reversal Acoustics, 43–48. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-3235-8_6.

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Gan, Woon Siong. « Parity–Time Invariance ». Dans Time Reversal Acoustics, 49–57. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-3235-8_7.

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Gan, Woon Siong. « Topology in Acoustics and Topological Sound Waves ». Dans Time Reversal Acoustics, 77–82. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-3235-8_11.

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Gan, Woon Siong. « Linear Time-Reversal Acoustics ». Dans Time Reversal Acoustics, 15–21. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-3235-8_3.

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Actes de conférences sur le sujet "Acoustic tile"

Chu, Herman. « A Tile : A Look at Acoustic Fundamentals and Designs as Applied to Air-Cooled Electronics [How-To Presentation] ». Dans 2020 36th Semiconductor Thermal Measurement, Modeling & Management Symposium (SEMI-THERM). IEEE, 2020. http://dx.doi.org/10.23919/semi-therm50369.2020.9142848.

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Thompson, Lonny L. « A Multi-Field Space-Time Finite Element Method for Structural Acoustics ». Dans ASME 1995 Design Engineering Technical Conferences collocated with the ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/detc1995-0395.

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Abstract A Computational Structural Acoustics (CSA) capability for solving scattering, radiation, and other problems related to the acoustics of submerged structures has been developed by employing some of the recent algorithmic trends in Computational Fluid Dynamics (CFD), namely time-discontinuous Galerkin Least-Squares finite element methods. Traditional computational methods toward simulation of acoustic radiation and scattering from submerged elastic bodies have been primarily based on frequency domain formulations. These classical time-harmonic approaches (including boundary element, finite element, and finite difference methods) have been successful for problems involving a limited range of frequencies (narrow band response) and scales (wavelengths) that are large compared to the characteristic dimensions of the elastic structure. Attempts at solving large-scale structural acoustic systems with dimensions that are much larger than the operating wavelengths and which are complex, consisting of many different components with different scales and broadband frequencies, has revealed limitations of many of the classical methods. As a result, there has been renewed interest in new innovative approaches, including time-domain approaches. This paper describes recent advances in the development of a new class of high-order accurate and unconditionally stable space-time methods for structural acoustics which employ finite element discretization of the time domain as well as the usual discretization of the spatial domain. The formulation is based on a space-time variational equation for both the acoustic fluid and elastic structure together with their interaction. Topics to be discussed include the development and implementation of higher-order accurate non-reflecting boundary conditions based on the exact impedance relation through the. Dirichlet-to-Neumann (DtN) map, and a multi-field representation for the acoustic fluid based on independent pressure and velocity potential variables. Numerical examples involving radiation and scattering of acoustic waves are presented to illustrate the high-order accuracy achieved by the new methodology for CSA.

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Mihaˇescu, Mihai, Ephraim J. Gutmark et Laszlo Fuchs. « Computational Aeroacoustics of the Coaxial Flow Exhaust System of a Gas Turbine Engine ». Dans ASME Turbo Expo 2007 : Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-28193.

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Jet engine noise is an environmental problem that needs to be addressed. Several methods to reduce the jet noise have been proposed in the last decades. The main issue is to find methods that reduce noise without causing considerable loss of thrust. Experimental and computational tools are mandatory in successfully reducing jet engine noise emissions. One of the challenging issues of computing the jet engine noise is the presence of very large scales (associated with the wave length of the acoustic wave) and at the same time also small scales that are responsible for the acoustical sources. In the field of Computational Aero-Acoustics (CAA) different hybrid approaches have been introduced to handle the different scales using problem specific models and methods. Here, a decomposition of flow variables is used that allows separation of flow and acoustic computations. Large Eddy Simulation approach is employed to compute the flow field and the acoustic sources. An inhomogeneous wave equation is used to perform acoustic computations. The paper investigates numerically the flow and the near-field acoustic data from a coaxial jet case with chevrons on the core nozzle that are compared with those obtained from a baseline coaxial jet, showing the spatial character of the acoustic benefit when chevrons are used on the core nozzle. Comparisons in terms of sound pressure levels with experimental data performed with the same geometry show a good agreement.

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Kannan, Ashwin, et S. R. Chakravarthy. « A Framework to Predict Combustion Noise and Instability : Case Study of a Partially Premixed Flame in a Backward-Facing Step Combustor ». Dans ASME Turbo Expo 2017 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-65211.

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Incompressible large eddy simulations coupled with acoustics are performed to predict combustion noise and instability in a partially premixed based backward facing step combustor. The computational analysis adopts a simultaneous multi-scale spatio-temporal framework for flow and acoustics such that the flow/acoustics varies at a shorter/longer length scale and a longer/shorter time scale respectively. This engenders flow dilatation and acoustic Reynolds stress (ARS) as the external source terms in the acoustic energy and flow momentum respectively. Numerical results are presented for three cases, at a particular Reynolds number, wherein two of them constitute acoustically coupled (coupled long duct case) and its uncoupled counterpart (no acoustic feedback). The third corresponds to a shorter combustor length (coupled short duct case). These three cases contrast the strong acoustic feedback in the short duct case, both of which are compared with the acoustically uncoupled LES that is common to them. It is found that combustion occurs predominantly in the large-scale vortical structures in the coupled long duct case due to enhanced mixing between the reactants brought about by the strong acoustic feedback (ARS). Thus, the present work is able to not only distinguish between the flow and acoustic processes, but also handle both combustion noise and instability within the same framework.

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Akhmedzhanov, F. R. « Application of acoustical activity for measurement of acoustic wave frequency ». Dans 2009 Joint Meeting of the European Frequency and Time Forum (EFTF) and the IEEE International Frequency Control Symposium (FCS). IEEE, 2009. http://dx.doi.org/10.1109/freq.2009.5168255.

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Shiohata, K., K. Nemoto et T. Iwatsubo. « A Method for Large-Scale Structural-Acoustic Analysis ». Dans ASME 1997 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/detc97/vib-3834.

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Abstract This paper presents a method for large-scale structural-acoustic analysis in which a cavity is divided into several acoustic fields, and a transfer-function method is used to solve the acoustics efficiently. By solving simultaneous equations using the Gaussian elimination method sequentially for each pair of neighboring acoustic sub-fields, the calculation time and memory requirements are reduced. Calculation accuracy is the same as when calculating the entire acoustic field without first dividing it. We created two kinds of closed acoustic models (cavity models) and carried out numerical simulations. The results showed that the proposed method is effective for large-scale structural-acoustic analysis.

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Corcoran, Joseph M., et Ricardo A. Burdisso. « An Energy Diffusion Model for Interior Acoustics With Structural Coupling Using the Boundary Element Method ». Dans ASME 2012 Noise Control and Acoustics Division Conference at InterNoise 2012. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ncad2012-0953.

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Recently, a new model for the propagation of sound in interior volumes known as the acoustic diffusion equation has been explored as an alternative method for acoustic predictions and analysis. The model uses statistical methods standard in high frequency room acoustics to compute a spatial distribution of acoustic energy over time as a diffusion process. For volumes coupled through a structural partition, the energy consumed by structural vibration and acoustic energy transmitted between volumes has been incorporated through a simple acoustic transmission coefficient. In this paper, a Boundary Element Method (BEM) solution to the simple diffusion model is developed. The integral form of the 3D acoustic diffusion equation for coupled volumes is derived using the Laplace transform and Green’s Second Identity. The solution using the BEM is developed as well as an efficient Laplace transform inversion scheme to obtain both steady state and transient interior acoustic energy. In addition, a fully coupled model where both structural and acoustic energy are computed as a diffusion process is proposed. A simple volume configuration is examined as the diffusion models are analyzed and compared to conventional room acoustics analysis methods. Advantages of the energy diffusion methods over conventional methods, such as computation of energy distributions and accurate transmission from one volume to another, are revealed as the comparisons are made.

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Schuermans, Bruno B. H., Wolfgang Polifke et Christian Oliver Paschereit. « Modeling Transfer Matrices of Premixed Flames and Comparison With Experimental Results ». Dans ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-132.

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A combined analytical/experimental investigation of the thermoacoustic properties of a gas turbine burner with a premixed, turbulent, swirl-stabilized flame is presented. In an enclosed flame, an interaction occurs between acoustic fluctuations and non-steady heat release, which may lead to thermoacoustic instabilities. This interaction may be characterized by the transfer matrix of the burner with flame. The transfer matrix describes the coupling between fluctuations of acoustic pressure and velocity on both sides of burner and flame, incorporating also the effects of heat release fluctuations on the acoustic quantities. The transfer matrix has been modeled and validated with experimental results. For the burner, an analytical model is proposed, which is based on the Bernoulli equation for instationary flow through compact elements. The model is based on the Rankine-Hugoniot relations across a thin heat source. The fundamental assumption underlying the model is that acoustic fluctuations cause modulations of fuel concentrations at the fuel injector, which result, after a certain time lag, in a fluctuating heat release rate at the flame. The oscillating heat release couples with pressure and velocity fluctuations in the combustion chamber, thereby creating a feedback loop between combustor acoustics and flame dynamics which may result in self-excited combustion instability. The transfer matrix of the burner with flame has been determined experimentally in an atmospheric combustion test facility. The test rig was equipped with loudspeakers and microphones in order to measure the response to an acoustical excitation. Our new flame model shows to be in agreement with the measured results.

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Szasz, Robert Z., Mihai Mihaescu et Laszlo Fuchs. « Computation of the Acoustic Field in an Annular Gas Turbine Combustion Chamber Using a Hybrid Approach ». Dans ASME Turbo Expo 2006 : Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90024.

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The acoustic field generated by flow unsteadiness in a model annular gas turbine (GT) combustion chamber is determined using a hybrid approach. In the flow solver the semi-compressible Navier-Stokes equations are resolved using LES as turbulence model. The acoustic solver is based on an inhomogeneous wave equation, where the instantaneous source terms are computed from the LES data in each time-instant. The flow and the acoustics in a GT combustor with co- and counter-rotating swirler burners have been considered. The results have shown that significant differences can be observed between the co- and counter-rotating configurations both in the flow and acoustic fields.

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Haeringer, Matthias, et Wolfgang Polifke. « Time Domain Bloch Boundary Conditions for Efficient Simulation of Thermoacoustic Limit-Cycles in (Can-)Annular Combustors ». Dans ASME Turbo Expo 2019 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91604.

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Abstract Thermo-acoustic eigenmodes of annular or can-annular combustion chambers, which typically feature a discrete rotational symmetry, may be computed in an efficient manner by utilizing the Bloch-wave theory. Unfortunately, the application of the Bloch-wave theory to combustion dynamics has hitherto been limited to the frequency domain. In this study we present a time domain formulation of Bloch boundary conditions (BBC), which allows to employ them in time domain simulations, e.g. CFD simulations. The BBCs are expressed as acoustic scattering matrices and translated to complex-valued state-space systems. In a hybrid approach an unsteady, compressible CFD simulation of the burner-flame zone is coupled via characteristic-based state-space boundary-conditions to a reduced order model of the combustor acoustics that includes BBCs. The acoustic model with BBC accounts for cross-can acoustic coupling and the discrete rotational symmetry of the configuration, while the CFD simulation accounts for the nonlinear flow-flame-acoustic interactions. This approach makes it possible to model limit cycle oscillations of (can-)annular combustors at drastically reduced computational cost compared to CFD simulations of the full configuration, and without the limitations of weakly nonlinear approaches that utilize a flame describing function. In the current study the suggested approach is applied to a generic multi-can combustor. Results agree well with a fully compressible CFD simulation of the complete configuration.

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Rapports d'organisations sur le sujet "Acoustic tile"

Carey, William M., et William B. Moseley. Space Time Processing, Environmental-Acoustic Effects. Fort Belvoir, VA : Defense Technical Information Center, août 1987. http://dx.doi.org/10.21236/ada190764.

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Gur, Ilan. Real-Time Acoustic Analysis of Batteries. Office of Scientific and Technical Information (OSTI), mars 2020. http://dx.doi.org/10.2172/1607788.

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Dowling, David R. Acoustic Time Reversal in the Shallow Ocean. Fort Belvoir, VA : Defense Technical Information Center, mars 2005. http://dx.doi.org/10.21236/ada430812.

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Aldridge, David Franklin, Sandra L. Collier, David H. Marlin, Vladimir E. Ostashev, Neill Phillip Symons et D. Keith Wilson. Staggered-grid finite-difference acoustic modeling with the Time-Domain Atmospheric Acoustic Propagation Suite (TDAAPS). Office of Scientific and Technical Information (OSTI), mai 2005. http://dx.doi.org/10.2172/966592.

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Norton, Steve, I. J. Won, Alan Witten, Alex Oren et Frank Funak. Time-Exposure Acoustics for Imaging Underground Structures. Fort Belvoir, VA : Defense Technical Information Center, septembre 2003. http://dx.doi.org/10.21236/ada417769.

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Quatieri, Thomas F., Robert B. Dunn, Robert J. McAulay et Thomas E. Hanna. Time-Scale Modification of Complex Acoustic Signals in Noise. Fort Belvoir, VA : Defense Technical Information Center, février 1994. http://dx.doi.org/10.21236/ada277535.

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Williams, William J. Investigation of New Time-Frequency Analyses for Acoustic Transients. Fort Belvoir, VA : Defense Technical Information Center, avril 1995. http://dx.doi.org/10.21236/ada300339.

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Williams, William J. Reduced Interference Time-Frequency Distributions : Applications to Acoustic Transients. Fort Belvoir, VA : Defense Technical Information Center, janvier 1990. http://dx.doi.org/10.21236/ada241104.

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Kalcic, Maria T., Andrew B. Martinez et Douglas N. Lambert. Time-Frequency Analysis of Acoustic Imagery for Bottom Mapping. Fort Belvoir, VA : Defense Technical Information Center, novembre 1998. http://dx.doi.org/10.21236/ada358755.

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Job, Jacob. Mesa Verde National Park : Acoustic monitoring report. National Park Service, juillet 2021. http://dx.doi.org/10.36967/nrr-2286703.

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In 2015, the Natural Sounds and Night Skies Division (NSNSD) received a request to collect baseline acoustical data at Mesa Verde National Park (MEVE). Between July and August 2015, as well as February and March 2016, three acoustical monitoring systems were deployed throughout the park, however one site (MEVE002) stopped recording after a couple days during the summer due to wildlife interference. The goal of the study was to establish a baseline soundscape inventory of backcountry and frontcountry sites within the park. This inventory will be used to establish indicators and thresholds of soundscape quality that will support the park and NSNSD in developing a comprehensive approach to protecting the acoustic environment through soundscape management planning. Additionally, results of this study will help the park identify major sources of noise within the park, as well as provide a baseline understanding of the acoustical environment as a whole for use in potential future comparative studies. In this deployment, sound pressure level (SPL) was measured continuously every second by a calibrated sound level meter. Other equipment included an anemometer to collect wind speed and a digital audio recorder collecting continuous recordings to document sound sources. In this document, “sound pressure level” refers to broadband (12.5 Hz–20 kHz), A-weighted, 1-second time averaged sound level (LAeq, 1s), and hereafter referred to as “sound level.” Sound levels are measured on a logarithmic scale relative to the reference sound pressure for atmospheric sources, 20 μPa. The logarithmic scale is a useful way to express the wide range of sound pressures perceived by the human ear. Sound levels are reported in decibels (dB). A-weighting is applied to sound levels in order to account for the response of the human ear (Harris, 1998). To approximate human hearing sensitivity, A-weighting discounts sounds below 1 kHz and above 6 kHz. Trained technicians calculated time audible metrics after monitoring was complete. See Methods section for protocol details, equipment specifications, and metric calculations. Median existing (LA50) and natural ambient (LAnat) metrics are also reported for daytime (7:00–19:00) and nighttime (19:00–7:00). Prominent noise sources at the two backcountry sites (MEVE001 and MEVE002) included vehicles and aircraft, while building and vehicle predominated at the frontcountry site (MEVE003). Table 1 displays time audible values for each of these noise sources during the monitoring period, as well as ambient sound levels. In determining the current conditions of an acoustical environment, it is informative to examine how often sound levels exceed certain values. Table 2 reports the percent of time that measured levels at the three monitoring locations were above four key values.

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