The Measurement Of Sound Absorption Coefficient In Situ For Fibrous And Porous Materials With Low Absorption Coefficient Values
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The Measurement Of Sound Absorption Coefficient In Situ For Fibrous And Porous Materials With Low Absorption Coefficient Values
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Author : Clifford Douglas Free
language : en
Publisher:
Release Date : 1985
The Measurement Of Sound Absorption Coefficient In Situ For Fibrous And Porous Materials With Low Absorption Coefficient Values written by Clifford Douglas Free and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with Absorption of sound categories.
Propagation Of Sound In Porous Media
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Author : J.F. Allard
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Propagation Of Sound In Porous Media written by J.F. Allard and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Technology & Engineering categories.
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.
Acoustical Properties Of Highly Porous Fibrous Materials
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Author :
language : en
Publisher:
Release Date : 1979
Acoustical Properties Of Highly Porous Fibrous Materials written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1979 with categories.
Constructing The Future
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Author : Ghassan Aouad
language : en
Publisher: Routledge
Release Date : 2006-12-05
Constructing The Future written by Ghassan Aouad and has been published by Routledge this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006-12-05 with Technology & Engineering categories.
This essential book introduces the concept of nD modelling, which takes the theory of computer modelling of the built environment to n dimensions. nD modelling utilizes a decision support tool for systematic assessment and comparison between various design parameters such as cost, accessibility, maintainability, sustainability, crime, energy, whole life costing, acoustics and scheduling among others. Constructing the Future is a comprehensive book which provides a global perspective on the concept of nD modelling and examines its impact on construction, from development to application. The text offers a critique of competing views that seek to justify (or ignore) the role of nD modelling in the future of construction as well as describing developments in this area which are already happening worldwide. Presenting a thorough critique of competing views as well as providing guidance on best practice, Constructing the Future is a bold, well-grounded and illustrated title introducing construction management professionals and researchers to this exciting new development in the quest for a single building and product model.
Acoustic Absorbers And Diffusers
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Author : Trevor Cox
language : en
Publisher: CRC Press
Release Date : 2016-11-18
Acoustic Absorbers And Diffusers written by Trevor Cox and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-11-18 with Technology & Engineering categories.
This definitive guide covers the design and application of absorbers and diffusers in acoustics. Surface diffusion is a relatively young subject area, and diffuser design, application and characterisation are often not well understood. Although there is greater knowledge of absorption, it is also informed by new research. As two of the main design tools for altering the acoustic conditions of rooms, the correct use of absorbers and diffusers is important to the creation of quality acoustics. This text details the evolution and the current state of the art in diffuser and absorber research and application. It covers a range of practical and theoretical aspects, with extensive examples of installations and case studies to cater to practitioners working in the measurement, modelling and design of rooms, semi-enclosed spaces as well as in noise control. It is also invaluable for students and researchers wanting a grounding in acoustic treatment, as well as understanding the latest developments. All chapters have been revised and brought up to date in this new edition, with new applications, absorbers and diffusers featured. Sustainability, portable vocal booths, and fast time domain models for diffusers are just a few of the new sections. Improved techniques for measurement and prediction are included, as well as bringing old methods up-to-date with the latest refinements from standards and research. Most of the prediction methods in the book are now linked to open source implementations and downloadable MATLAB scripts, enabling readers to exploit the knowledge in this book more readily in design and research.
Separation Technologies For Minerals Coal And Earth Resources
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Author : Courtney Young
language : en
Publisher: SME
Release Date : 2012
Separation Technologies For Minerals Coal And Earth Resources written by Courtney Young and has been published by SME this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Technology & Engineering categories.
This book is an authoritative digest of the latest developments in the mineral processing industry. Dozens of authors share their insights on how practitioners can develop earth resources more economically while simultaneously addressing vital factors ranging from sustainability to environmental stewardship. The book examines coal processing, surface forces and hydrophobicity, process improvements and environmental controls, dewatering and drying, gravity separations, industrial minerals flotation, base metal flotation, flotation equipment and practice, process reagents, magnetic and electrostatic separations, modeling and process control, and resource engineering. Important current issues such as gas hydrates, oil sands, secondary materials, metals and waste, and process waters are also discussed.
Measurement Of Acoustic Impedance And Absorption Coefficient
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Author : E. C. Wente
language : en
Publisher:
Release Date : 1928
Measurement Of Acoustic Impedance And Absorption Coefficient written by E. C. Wente and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1928 with Acoustic impedance categories.
Investigation Of Inverse Acoustical Characterization Of Porous Materials Used In Aircraft Noise Control Application
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Author : Apoorv Ravindran
language : en
Publisher:
Release Date : 2007
Investigation Of Inverse Acoustical Characterization Of Porous Materials Used In Aircraft Noise Control Application written by Apoorv Ravindran and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Electronic dissertations categories.
Sound propagation through porous media such as foams and fibers is governed by five parameters that describe the geometry of the porous frame: porosity, tortuosity, flow resistivity, viscous characteristic length, and thermal characteristic length. The conventional laboratory methods for measuring these geometric properties are prone to errors and can be highly cumbersome. In this work, an alternative method of determining the geometric properties of porous materials, based on an inverse acoustical technique, was investigated for materials used in aircraft noise-control applications. This technique is incorporated in commercial software codes, such as FOAM-X (ESI Group) and Comet TrimTM (Comet Acoustics), which require the absorption coefficient and/or transmission loss (TL) to be measured in Brüel and Kjær (or equivalent) standing wave tubes as inputs. The estimated geometric properties are required to define the porous material for complex vibroacoustic analysis in commercial code such as AutoSEA2 (ESI Group). One of the goals of this work was to evaluate the accuracy of the estimated geometric properties. A closed-loop validation technique was previously developed where the absorption coefficient and transmission loss were predicted using AutoSEA2 and compared with the standing wave tube measurements. Good agreement between the measured and predicted absorption coefficient was observed for both foams and fibers. However, in the case of transmission loss, good agreement was observed for fibers but not for foams. In order to eliminate inconsistencies, the existing validation loop was modified by incorporating Comet TrimTM inverse characterization software that took both the normal incidence absorption coefficient and transmission loss as sequential inputs to estimate the geometric properties. To complete the modified loop, sound absorption and transmission loss of porous materials was predicted using the performance analysis module in Comet TrimTM and compared with the test results. In general, the absorption coefficient of most of the foams and fibers, prediction using both validation loops was in good correlation with the measured data. On the other hand, the correlation in normal incidence transmission loss was better using the modified loop. In the process of investigating the repeatability of estimating the physical properties, previously measured porous material samples were re-measured for their absorption coefficient and transmission loss. A possible effect of sample aging was discovered and reported. As an alternate method to the forward TL calculation, a finite element model of the standing wave tube was also developed. This could be used to study the effect of boundary conditions on acoustic properties. Finally, individually validated samples were combined to develop optimized multilayer aircraft noise-control treatments and were experimentally demonstrated to produce excellent acoustical performance.
The Journal Of The Acoustical Society Of America
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Author :
language : en
Publisher:
Release Date : 1977
The Journal Of The Acoustical Society Of America written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977 with Music categories.
In Situ Measurements Of Acoustic Properties Of Surfaces
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Author : Scott W. Mallais
language : en
Publisher:
Release Date : 2009
In Situ Measurements Of Acoustic Properties Of Surfaces written by Scott W. Mallais and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The primary goal of this work is to measure the acoustic properties of a surface in situ. This generally involves sound pressure measurements and a calculation of the acoustic reflection factor of a surface, which may then be used to calculate the acoustic impedance or the acoustic absorption coefficient. These quantities are of use in acoustic simulations, architectural design, room acoustics and problems in noise control. It is of great interest to determine the performance of a particular surface where it is used, as opposed to measurements conducted in a laboratory. In situ measurements are not trivial, caution must be taken to ensure that high signal-to-noise levels are achieved and that the reflections of sound from the measurement environment are taken into consideration. This study presents five measurement methods that may be applied in situ. The acoustic absorption coefficient is calculated for each method on various surfaces spanning the whole range of absorption. Emphasis is placed on frequency resolution, in order to determine absorption characteristics in the bass region (50 Hz to 200 Hz). Advantages and disadvantages of each method are demonstrated and discussed. Finally, the in situ implementation of the surface pressure method is presented and measurements are made in order to test the limitations of this approach.