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Low Frequency Sound Propagation In Porous Media
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Book Synopsis Propagation of Sound in Porous Media by : J.F. Allard
Download or read book Propagation of Sound in Porous Media written by J.F. Allard and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book has grown out of the research activities of the author in the fields of sound propagation in porous media and modelling of acoustic materials. It is assumed that the reader has a background of advanced calculus, including an introduction to differential equations, complex variables and matrix algebra. A prior exposure to theory of elasticity would be advantageous. Chapters 1-3 deal with sound propagation of plane waves in solids and fluids, and the topics of acoustic impedance and reflection coefficient are given a large emphasis. The topic of flow resistivity is presented in Chapter 2. Chapter 4 deals with sound propagation in porous materials having cylindrical pores. The topics of effective density, and of tortuosity, are presented. The thermal exchanges between the frame and the fluid, and the behaviour of the bulk modulus of the fluid, are described in this simple context. Chapter 5 is concerned with sound propagation in other porous materials, and the recent notions of characteristic dimensions, which describe thermal exchanges and the viscous forces at high frequencies, are introduced. In Chapter 6, the case of porous media having an elastic frame is considered in the context of Biot theory, where new topics described in Chapter 5 have been included.
Book Synopsis Low-frequency Sound Propagation in Porous Media by : Michael J. White
Download or read book Low-frequency Sound Propagation in Porous Media written by Michael J. White and published by . This book was released on 2011 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Behavior of Low-frequency Sound Waves in Porous Media by : Tyler J. Rossi
Download or read book Behavior of Low-frequency Sound Waves in Porous Media written by Tyler J. Rossi and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a study of the relationship between the measured acoustic parameters and the measured physical parameters of porous media. Materials studied include crushed limestone, stream-formed pea gravel, large and small sifted pea gravels, and glass spheres. A standing wave curve fitting algorithm was applied to data taken from a vertical impedance tube to determine the propagation and reflection parameters of the materials. Physical characteristics considered include porosity, tortuosity, and flow resistivity.
Book Synopsis Springer Handbook of Acoustics by : Thomas Rossing
Download or read book Springer Handbook of Acoustics written by Thomas Rossing and published by Springer Science & Business Media. This book was released on 2007-06-21 with total page 1179 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an unparalleled modern handbook reflecting the richly interdisciplinary nature of acoustics edited by an acknowledged master in the field. The handbook reviews the most important areas of the subject, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest research and applications are incorporated throughout, including computer recognition and synthesis of speech, physiological acoustics, diagnostic imaging and therapeutic applications and acoustical oceanography. An accompanying CD-ROM contains audio and video files.
Book Synopsis Enhancement of the Low Frequency Sound Absorption of Porous Materials by Addition of a Thin High Flow-resistivity Cover Layer by : Jeremy A. Lambert
Download or read book Enhancement of the Low Frequency Sound Absorption of Porous Materials by Addition of a Thin High Flow-resistivity Cover Layer written by Jeremy A. Lambert and published by . This book was released on 2007 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: The general performance of a porous material against a rigid backing shows very good absorption qualities at high frequencies, but at lower frequencies, where the thickness becomes much less than a wavelength of sound, the absorption is considerably reduced. Based on observations noted during outdoor sound propagation studies and published literature on layered sound absorbing structures, the addition of a thin cover with a high flow-resistivity cover layer can enhance low frequency sound absorption. The objective of this studies was to examine the possibility of increasing low frequency without significantly reducing higher frequency absorption, which usually occurs. The sound absorbing materials were modelled as porous media with complex characteristic impedance and wave number that were obtained using a single flow resistivity parameter based on a widely-used semi-empirical model due to Delany and Bazley (1971). After a thorough parametrical study, experiments were performed to validate the modelling approach, an optimisations was run in order to seek the best combination of flow resistances and layer thicknesses for a given performance requirement.
Book Synopsis The Propagation of Low Frequency Sound Through an Audience by : Elena Shabalina
Download or read book The Propagation of Low Frequency Sound Through an Audience written by Elena Shabalina and published by Logos Verlag Berlin GmbH. This book was released on 2014 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: At large outdoor concerts or festivals subwoofers, the dedicated low frequency loudspeakers, are often placed in a row in front of the stage as an evenly spaced array in order to control the directivity of sound at low frequencies. The audience itself often stands tightly packed in front of the array, so that sound waves propagate partly through the audience and partly over it. This thesis presents an investigation on how exactly the presence of the audience influences the propagation of sound. A mathematical model of an audience as an equivalent fluid is constructed with the help of the porous medium theory. The equivalent fluid parameters, such as the wave impedance, the speed of sound and the reflection coefficient from the audience/air boundary, are calculated both for a constant and a variable concentration of an audience. The model is verified by a Boundary Element Method simulation, scale measurements and live concert measurements. A new live measurement method is developed to evaluate the low frequency sound pressure level distribution without disturbing the ongoing event. The study reaches the conclusion that at low frequencies an audience forms a medium with the impedance significantly different from the impedance of the air, which leads to the reflection of sound waves from the boundaries back into the audience and increase of the sound pressure level as well as interference effects. Possible applications of the findings are mainly sound system design and event planning.
Book Synopsis Computational and Experimental Studies of Acoustic Waves by : Mahmut Reyhanoglu
Download or read book Computational and Experimental Studies of Acoustic Waves written by Mahmut Reyhanoglu and published by BoD – Books on Demand. This book was released on 2018-01-04 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents recent studies of acoustic wave propagation through different media including the atmosphere, Earth's subsurface, complex dusty plasmas, porous materials, and flexible structures. Mathematical models of the underlying physical phenomena are introduced and studied in detail. With its seven chapters, the book brings together important contributions from renowned international researchers to provide an excellent survey of recent computational and experimental studies of acoustic waves. The first section consists of four chapters that focus on computational studies, while the next section is composed of three chapters that center on experimental studies.
Book Synopsis Low-frequency Sound Wave Behavior in Porous Media by : Timothy E. Onder
Download or read book Low-frequency Sound Wave Behavior in Porous Media written by Timothy E. Onder and published by . This book was released on 2008 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Propagation of Sound in Porous Media by : J.F. Allard
Download or read book Propagation of Sound in Porous Media written by J.F. Allard and published by Springer. This book was released on 2012-01-07 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book has grown out of the research activities of the author in the fields of sound propagation in porous media and modelling of acoustic materials. It is assumed that the reader has a background of advanced calculus, including an introduction to differential equations, complex variables and matrix algebra. A prior exposure to theory of elasticity would be advantageous. Chapters 1-3 deal with sound propagation of plane waves in solids and fluids, and the topics of acoustic impedance and reflection coefficient are given a large emphasis. The topic of flow resistivity is presented in Chapter 2. Chapter 4 deals with sound propagation in porous materials having cylindrical pores. The topics of effective density, and of tortuosity, are presented. The thermal exchanges between the frame and the fluid, and the behaviour of the bulk modulus of the fluid, are described in this simple context. Chapter 5 is concerned with sound propagation in other porous materials, and the recent notions of characteristic dimensions, which describe thermal exchanges and the viscous forces at high frequencies, are introduced. In Chapter 6, the case of porous media having an elastic frame is considered in the context of Biot theory, where new topics described in Chapter 5 have been included.
Book Synopsis Wave Propagation in Porous Materials by : Zine El Abiddine
Download or read book Wave Propagation in Porous Materials written by Zine El Abiddine and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter provides different models for the acoustic wave propagation in porous materials having a rigid and an elastic frames. The direct problem of reflection and transmission of acoustic waves by a slab of porous material is studied. The inverse problem is solved using experimental reflected and transmitted signals. Both high- and low-frequency domains are studied. Different acoustic methods are proposed for measuring physical parameters describing the acoustic propagation as porosity, tortuosity, viscous and thermal characteristic length, and flow resistivity. Some advantages and perspectives of this method are discussed.
Book Synopsis Multi-Component Acoustic Characterization of Porous Media by : Karel N. van Dalen
Download or read book Multi-Component Acoustic Characterization of Porous Media written by Karel N. van Dalen and published by Springer Science & Business Media. This book was released on 2013-01-11 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: The feasibility to extract porous medium parameters from acoustic recordings is investigated. The thesis gives an excellent discussion of our basic understanding of different wave modes, using a full-waveform and multi-component approach. Focus lies on the dependency on porosity and permeability where especially the latter is difficult to estimate. In this thesis, this sensitivity is shown for interface-wave and reflected-wave modes. For each of the pseudo-Rayleigh and pseudo-Stoneley interface waves unique estimates for permeability and porosity can be obtained when impedance and attenuation are combined. The pseudo-Stoneley wave is most sensitive to permeability: both the impedance and the attenuation are controlled by the fluid flow. Also from reflected-wave modes unique estimates for permeability and porosity can be obtained when the reflection coefficients of different reflected modes are combined. In this case the sensitivity to permeability is caused by subsurface heterogeneities generating mesoscopic fluid flow at seismic frequencies. The results of this thesis suggest that estimation of in-situ permeability is feasible, provided detection is carried out with multi-component measurements. The results of this thesis argely affect geotechnical and reservoir engineering practices.
Book Synopsis Acoustic Waves in Periodic Structures, Metamaterials, and Porous Media by : Noé Jiménez
Download or read book Acoustic Waves in Periodic Structures, Metamaterials, and Porous Media written by Noé Jiménez and published by Springer Nature. This book was released on 2021-11-03 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book delivers a comprehensive and up-to-date treatment of practical applications of metamaterials, structured media, and conventional porous materials. With increasing levels of urbanization, a growing demand for motorized transport, and inefficient urban planning, environmental noise exposure is rapidly becoming a pressing societal and health concern. Phononic and sonic crystals, acoustic metamaterials, and metasurfaces can revolutionize noise and vibration control and, in many cases, replace traditional porous materials for these applications. In this collection of contributed chapters, a group of international researchers reviews the essentials of acoustic wave propagation in metamaterials and porous absorbers with viscothermal losses, as well as the most recent advances in the design of acoustic metamaterial absorbers. The book features a detailed theoretical introduction describing commonly used modelling techniques such as plane wave expansion, multiple scattering theory, and the transfer matrix method. The following chapters give a detailed consideration of acoustic wave propagation in viscothermal fluids and porous media, and the extension of this theory to non-local models for fluid saturated metamaterials, along with a description of the relevant numerical methods. Finally, the book reviews a range of practical industrial applications, making it especially attractive as a white book targeted at the building, automotive, and aeronautic industries.
Book Synopsis Sound Propagation in the Sea by : Robert J. Urick
Download or read book Sound Propagation in the Sea written by Robert J. Urick and published by . This book was released on 1979 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Poromechanics written by J.F. Thimus and published by CRC Press. This book was released on 2020-12-18 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text features 105 papers dealing with the fundamentals and the applications of poromechanics from the Biot conference of 1998, held in Louvain-la-Neuve. Topics include: wave propogation; numerical modelling; identification of poromechanical parameters; and constitutive modelling.
Book Synopsis Methods of the Physics of Porous Media by :
Download or read book Methods of the Physics of Porous Media written by and published by Academic Press. This book was released on 1999-07-09 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past 25 years, the field of VUV physics has undergone significant developments as new powerful spectroscopic tools, VUV lasers, and optical components have become available. This volume is aimed at experimentalists who are in need of choosing the best type of modern instrumentation in this applied field. In particular, it contains a detailed chapter on laboratory sources. This volume provides an up-to-date description of state-of-the-art equipment and techniques, and a broad reference bibliography. It treats phenomena from the standpoint of an experimental physicist, whereby such topics as imaging techniques (NMR, X-ray, ultrasonic, etc.) computer modeling, eletro-kinetic phenomena, diffusion, non-linear wave propagation surface adsorption/desorption, convective mixing, and fracture are specifically addressed.
Book Synopsis Acoustic Absorbers and Diffusers by : Trevor J. Cox
Download or read book Acoustic Absorbers and Diffusers written by Trevor J. Cox and published by CRC Press. This book was released on 2009-01-26 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: Absorbers and diffusers are two of the main design tools for altering the acoustic conditions of rooms, semi-enclosed spaces and the outdoor environment. Their correct use is important for delivering high quality acoustics. Unique and authoritative, this book decribes how to effectively measure, model, design and apply diffusers and absorbers. It is a resource for new and experienced acousticians, seeking an understanding of the evolution, characteristics and application of modern diffusers. Absorption is a more established technology and so the book blends traditional designs with modern developments. The book covers practical and theoretical aspects of absorbers and diffusers and is well illustrated with examples of installations and case studies. This new edition brings Acoustic Absorbers and Diffusers up-to-date with current research, practice and standards. New developments in measurement, materials, theory and practice since the first edition (published in 2004) are included. The sections on absorbers are extended to include more about noise control.
Book Synopsis Foundations of Vibroacoustics by : Colin Hansen
Download or read book Foundations of Vibroacoustics written by Colin Hansen and published by CRC Press. This book was released on 2018-03-05 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text provides the foundation material for solving problems in vibroacoustics. These include the prediction of structural vibration levels and sound pressure levels in enclosed spaces resulting from known force or acoustic pressure excitations and the prediction of sound levels radiated by vibrating structures. The book also provides an excellent theoretical basis for understanding the processes involved in software that predicts structural vibration levels and structural sound radiation resulting from force excitation of the structure, as well as sound levels in enclosed spaces resulting from vibration of part of the enclosing structure or resulting from acoustic sources within the enclosure. The book is written in an easy to understand style with detailed explanations of important concepts. It begins with fundamental concepts in vibroacoustics and provides a framework for problem solution in both low and high frequency ranges. It forms a primer for students, and for those already well versed in vibroacoustics, the book provides an extremely useful reference. It offers a unified treatment of both acoustics and vibration fundamentals to provide a basis for solving problems involving structural vibration, sound radiation from vibrating structures, sound in enclosed spaces, and propagation of sound and vibration.
