scholarly journals Acoustic Characterization of Fluorinert FC-43 Liquid with Helium Gas Bubbles: Numerical Experiments

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Christian Vanhille ◽  
Cristian Pantea ◽  
Dipen N. Sinha
Keyword(s):  
Sound Speed ◽  
Numerical Experiments ◽  
Underwater Acoustics ◽  
Gas Bubbles ◽  
Acoustic Characteristics ◽  
Parametric Generation ◽  
Acoustic Characterization ◽  
Helium Gas ◽  
High Sound

In this work, we define the acoustic characteristics of a biphasic fluid consisting of static helium gas bubbles in liquid Fluorinert FC-43 and study the propagation of ultrasound of finite amplitudes in this medium. Very low sound speed and high sound attenuation are found, in addition to a particularly high acoustic nonlinear parameter. This result suggests the possibility of using this medium as a nonlinear enhancer in various applications. In particular, parametric generation of low ultrasonic frequencies is studied in a resonator cavity as a function of driving pressure showing high conversion efficiency. This work suggests that this medium could be used for applications such as parametric arrays, nondestructive testing, diagnostic medicine, sonochemistry, underwater acoustics, and ultrasonic imaging and to boost the shock formation in fluids.

Characterization of the Content of the Cavity Behind a High-Speed Supercavitating Body

2006 ◽  
Vol 129 (2) ◽  
pp. 136-145 ◽  
Author(s):  
Xiongjun Wu ◽  
Georges L. Chahine
Keyword(s):  
Sound Speed ◽  
High Speed ◽  
Test Facility ◽  
Direct Visualization ◽  
Acoustic Measurements ◽  
Supercavitating Flow ◽  
Flow Test ◽  
High Sound ◽  
Very High

A high speed/high flow test facility was designed and implemented to study experimentally the supercavitating flow behind a projectile nose in a controlled laboratory setting. The simulated projectile nose was held in position in the flow and the cavity interior was made visible by having the walls of the visualization facility “cut through” the supercavity. Direct visualization of the cavity interior and measurements of the properties of the cavity contents were made. Transducers were positioned in the test section within the supercavitation volume to enable measurement of the sound speed and attenuation as a function of the flow and geometry parameters. These characterized indirectly the content of the cavity. Photography, high speed videos, and acoustic measurements were used to investigate the contents of the cavity. A side sampling cell was also used to sample in real time the contents of the cavity and measure the properties. Calibration tests conducted in parallel in a vapor cell enabled confirmation that, in absence of air injection, the properties of the supercavity medium match those of a mixture of water vapor and water droplets. Such a mixture has a very high sound speed with strong sound attenuation. Injection of air was also found to significantly decrease sound speed and to increase transmission.

Acoustic Characteristics of /s/ in Adolescents

1999 ◽  
Vol 42 (3) ◽  
pp. 663-677 ◽  
Author(s):  
Peter Flipsen ◽  
Lawrence Shriberg ◽  
Gary Weismer ◽  
Heather Karlsson ◽  
Jane McSweeny
Keyword(s):  
Reference Database ◽  
Linguistic Context ◽  
Spectral Moments ◽  
Data Set ◽  
Acoustic Characteristics ◽  
Acoustic Data ◽  
Acoustic Characterization ◽  
Acoustic Analyses ◽  
Age Range

The goal of the current study was to construct a reference database against which misarticulations of /s/ can be compared. Acoustic data for 26 typically speaking 9- to 15-year-olds were examined to resolve measurement issues in acoustic analyses, including alternative sampling points within the /s/ frication; the informativeness of linear versus Bark transformations of each of the 4 spectral moments of /s/ (Forrest, Weismer, Milenkovic, & Dougall, 1988); and measurement effects associated with linguistic context, age, and sex. Analysis of the reference data set indicates that acoustic characterization of /s/ is appropriately and optimally (a) obtained from the midpoint of /s/, (b) represented in linear scale, (c) reflected in summary statistics for the 1st and 3rd spectral moments, (d) referenced to individual linguistic-phonetic contexts, (e) collapsed across the age range studied, and (f) described individually by sex.

scholarly journals Evaluation of an acoustic conditioning panel made from typical Colombian fibres

2019 ◽  
pp. 102-116
Author(s):  
Darío Alfonso Páez Soto ◽  
Luis Jorge Herrera Fernández ◽  
Oscar Esneider Acosta Agudelo ◽  
Marcelo Herrera Martínez
Keyword(s):  
Sustainable Development ◽  
Rio De Janeiro ◽  
Natural Fibres ◽  
Acoustic Absorption ◽  
Absorption System ◽  
Acoustic Characteristics ◽  
Acoustic Behaviour ◽  
Acoustic Characterization ◽  
Acoustic Comfort

A perforated panel from guadua fibres is implemented after acoustic characterization of the fibres. The acoustic characteristics of the fibre are identified and further, the acoustic behaviour of the acoustic absorption system made from guadua is analysed. It proves the suitability of natural fibres and bioresidues for systems which goal is to bring acoustic comfort to society. In this sense, the present research is aligned with the principles of Sustainable Development agreed at Rio de Janeiro, in 1992. 

scholarly journals Acoustic characterization of a nonlinear vibroacoustic absorber at low frequencies and high sound levels

2018 ◽  
Vol 416 ◽  
pp. 244-257 ◽  
Author(s):  
A. Chauvin ◽  
M. Monteil ◽  
S. Bellizzi ◽  
R. Côte ◽  
Ph. Herzog ◽  
...  
Keyword(s):  
Low Frequencies ◽  
Sound Levels ◽  
Acoustic Characterization ◽  
High Sound

Acoustic Characterization of Marine Sediments

1997 ◽  
Author(s):  
Anatoliy N. Ivakin ◽  
Darrell R. Jackson
Keyword(s):  
Marine Sediments ◽  
Acoustic Characterization

Low temperature acoustic characterization of PMN single crystal

2017 ◽  
Vol 122 (8) ◽  
pp. 084103 ◽  
Author(s):  
E. Smirnova ◽  
A. Sotnikov ◽  
S. Ktitorov ◽  
H. Schmidt
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Acoustic Characterization

Acoustic characterization of silica nanoparticle-impregnated Kevlar fabric

2021 ◽  
pp. 004051752110238
Author(s):  
Oluwafemi P Akinmolayan ◽  
James M Manimala
Keyword(s):  
Transmission Loss ◽  
Silica Nanoparticle ◽  
Air Gap ◽  
Thin Plates ◽  
Residual Porosity ◽  
Ballistic Performance ◽  
Number Of Layers ◽  
Structural Applications ◽  
Acoustic Characterization

Silica nanoparticle-impregnated Kevlar (SNK) fabric has better specific ballistic performance in comparison to its neat counterparts. For multifunctional structural applications using lightweight composites, combining this improved ballistic functionality with an acoustic functionality is desirable. In this study, acoustic characterization of neat and SNK samples is conducted using the normal-incidence impedance tube method. Both the absorption coefficient and transmission loss (TL) are measured in the 60–6000 Hz frequency range. The influence of parameters such as number of layers of neat or treated fabric, percentage by weight of nanoparticle addition, spacing between fabric layers, and residual porosity is examined. It is found that while absorption decreases with an increase in nanoparticle addition for frequencies above about 2500 Hz, increasing the number of layers shifts peak absorption to lower frequencies. By introducing an air-gap behind the fabric layer, dominant low-frequency (1000–3000 Hz) absorption peaks are obtained that correlate well with natural modes of mass-equivalent thin plates. Examining the influence of residual porosity by laminating the SNK samples reveals that it contributes to about 30–50% of the total absorption. Above about 1500 Hz, 3–5 dB of TL increase is obtained for SNK samples vis-à-vis the neat samples. TL is found to increase beyond that of the neat sample above a threshold frequency when an air-gap is introduced between two SNK layers. With an increase in the weight of nanoparticle addition, measured TL tends to be closer to mass law predictions. This study demonstrates that SNK fabric could provide improved acoustic performance in addition to its ballistic capabilities, making it suitable for multifunctional applications and could form the basis for the development of simplified models to predict the structural acoustic response of such nanoparticle–fabric composites.

scholarly journals Acoustic Characterization of Some Steel Industry Waste Materials

2021 ◽  
Vol 11 (13) ◽  
pp. 5924
Author(s):  
Elisa Levi ◽  
Simona Sgarbi ◽  
Edoardo Alessio Piana
Keyword(s):  
Thermal Characteristic ◽  
Environmental Benefits ◽  
Acoustic Properties ◽  
Physical Parameters ◽  
Industry Waste ◽  
Acoustic Characterization ◽  
Minimization Procedure ◽  
The Difference ◽  
By Products

From a circular economy perspective, the acoustic characterization of steelwork by-products is a topic worth investigating, especially because little or no literature can be found on this subject. The possibility to reuse and add value to a large amount of this kind of waste material can lead to significant economic and environmental benefits. Once properly analyzed and optimized, these by-products can become a valuable alternative to conventional materials for noise control applications. The main acoustic properties of these materials can be investigated by means of a four-microphone impedance tube. Through an inverse technique, it is then possible to derive some non-acoustic properties of interest, useful to physically characterize the structure of the materials. The inverse method adopted in this paper is founded on the Johnson–Champoux–Allard model and uses a standard minimization procedure based on the difference between the sound absorption coefficients obtained experimentally and predicted by the Johnson–Champoux–Allard model. The results obtained are consistent with other literature data for similar materials. The knowledge of the physical parameters retrieved applying this technique (porosity, airflow resistivity, tortuosity, viscous and thermal characteristic length) is fundamental for the acoustic optimization of the porous materials in the case of future applications.

Acoustic characterization of laser-induced graphene film thermoacoustic loudspeakers

2019 ◽  
Author(s):  
Paolo La Torraca ◽  
Luca Larcher ◽  
Paolo Lugli ◽  
Marco Bobinger ◽  
Francisco J. Romero ◽  
...  
Keyword(s):  
Graphene Film ◽  
Acoustic Characterization
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