Nonlinear Acoustics: Periodic Waveguide, Finite-Amplitude Propagation in a Medium Having a Distribution of Relaxation Processes, and Production of an Isolated Negative Pulse in Water

1993 ◽  
Author(s):  
David T. Blackstock
Keyword(s):  
Nonlinear Acoustics ◽  
Finite Amplitude ◽  
Relaxation Processes ◽  
Periodic Waveguide ◽  
Negative Pulse

scholarly journals Directional Loudspeaker Using a Parametric Array

10.14311/862 ◽  
2006 ◽  
Vol 46 (4) ◽  
Author(s):  
A. Ritty
Keyword(s):  
Carrier Frequency ◽  
Nonlinear Acoustics ◽  
Finite Amplitude ◽  
Sound Beam ◽  
Sound Reproduction ◽  
Audible Sound ◽  
Parametric Array ◽  
Film Transducer

The theory for sound reproduction of parametric arrays is based on nonlinear acoustics. Due to the nonlinearity of the air, a finite amplitude ultrasound interacts with itself and generates audible secondary waves in the sound beam. A special feature of this loudspeaker is its sharper directivity compared to conventional loudspeakers of the same aperture size.This paper describes the basis of the theory used for parametric arrays, and presents the influence of the main parameters, e.g., carrier frequency. It also describes some signal pre-processing needed to obtain the desired audible sound. A PVDF (polyvinylidenefluoride) film transducer is also studied in order to produce a prototype to confirm the theory. 

Activation energy of relaxation processes in chalcogenide glasses

2013 ◽  
Vol 34 (0) ◽  
pp. 59-63
Author(s):  
А. А. Горват ◽  
В. М. Кришеник ◽  
А. Е. Кріштофорій ◽  
В. В. Мінькович ◽  
О. А. Молнар
Keyword(s):  
Activation Energy ◽  
Chalcogenide Glasses ◽  
Relaxation Processes

NONLINEAR ACOUSTICS APPLICATIONS FOR NEAR WELLBORE FORMATION EVALUATION

2020 ◽  
Author(s):  
Christopher Skelt ◽  
◽  
James TenCate ◽  
Robert Guyer ◽  
Paul Johnson ◽  
...  
Keyword(s):  
Nonlinear Acoustics ◽  
Formation Evaluation

Features of radiothermoluminescence of polypropylene and ethylene propylenediene elastomer SKEPT-4044 compositions with nanoscale metal-containing fillers

2020 ◽  
pp. 66-73
Author(s):  
A.M. Magerramov ◽  
◽  
N.I. Kurbanova ◽  
M.N. Bayramov ◽  
N.A. Alimirzoyeva ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Molecular Mobility ◽  
Fe3o4 Nanoparticles ◽  
Low Temperatures ◽  
Frost Resistance ◽  
Relaxation Processes ◽  
Ethylene Propylene ◽  
Temperature Range ◽  
Β Relaxation

Using radiothermoluminescence (RTL), the molecular mobility features in the temperature range of 77-300 K were studied for the polypropylene (PP)/ethylene propylene diene elastomer SKEPT-4044 with NiO, Cu2O and Fe3O4 nanoparticles (NPs) based on ABS-acrylonitrile butadiene or SCS-divinyl styrene matrices. It has been shown that the introduction of nanofillers in PP significantly affects the nature and temperature of γ- and β-relaxation processes, while the region of manifestation of the β-process noticeably shifts to the region of low temperatures. Composites with Cu2O NPs have a higher β-transition temperature Tβ than composites with other NPs. It was found that PP/SKEPT-4044 composites with Cu2O NPs with a dispersion of 11-15 nm and acrylonitrile butadiene thermoplastics have optimal frost resistance compared to other compositions.

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