Rectification of Acoustic Waves

1974 ◽  
Vol 52 (17) ◽  
pp. 1726-1730 ◽  
Author(s):  
S. S. Mathur ◽  
M. S. Sagoo
Keyword(s):  
Energy Density ◽  
Acoustic Wave ◽  
Acoustic Waves ◽  
Ultrasonic Waves ◽  
Pressure Amplitude ◽  
The Difference

The difference in the behavior of the denser and the rarer regions of a longitudinal travelling acoustic wave is utilized to produce the phenomenon of rectification of ultrasonic waves. It has been shown that, under appropriate conditions, the energy density of sound in the regions of rarefaction can be increased while in the regions of compression the energy density is decreased. It is found that under suitable conditions, the pressure amplitude in the rarer regions is about 4% larger than that in the denser regions. The measurement of this difference in amplitude can be used to determine the parameter of nonlinearity.

scholarly journals Inferring the chromospheric magnetic topology through waves

2007 ◽  
Vol 3 (S247) ◽  
pp. 78-81
Author(s):  
S. S. Hasan ◽  
O. Steiner ◽  
A. van Ballegooijen
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Energy Density ◽  
Acoustic Wave ◽  
Acoustic Waves ◽  
Phase Speed ◽  
Time Correlation ◽  
Propagation Time ◽  
Fast Mode ◽  
The Magnetic Field

AbstractThe aim of this work is to examine the hypothesis that the wave propagation time in the solar atmosphere can be used to infer the magnetic topography in the chromosphere as suggested by Finsterle et al. (2004). We do this by using an extension of our earlier 2-D MHD work on the interaction of acoustic waves with a flux sheet. It is well known that these waves undergo mode transformation due to the presence of a magnetic field which is particularly effective at the surface of equipartition between the magnetic and thermal energy density, the β = 1 surface. This transformation depends sensitively on the angle between the wave vector and the local field direction. At the β = 1 interface, the wave that enters the flux sheet, (essentially the fast mode) has a higher phase speed than the incident acoustic wave. A time correlation between wave motions in the non-magnetic and magnetic regions could therefore provide a powerful diagnostic for mapping the magnetic field in the chromospheric network.

scholarly journals Ground-based acoustic parametric generator impact on the atmosphere and ionosphere in an active experiment

2017 ◽  
Vol 35 (1) ◽  
pp. 53-70 ◽  
Author(s):  
Yuriy G. Rapoport ◽  
Oleg K. Cheremnykh ◽  
Volodymyr V. Koshovy ◽  
Mykola O. Melnik ◽  
Oleh L. Ivantyshyn ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Gravity Waves ◽  
Acoustic Waves ◽  
Difference Frequency ◽  
Sound Waves ◽  
Acoustic Gravity Waves ◽  
Active Experiment ◽  
The Difference ◽  
The Impact ◽  
Sound Generator

Abstract. We develop theoretical basics of active experiments with two beams of acoustic waves, radiated by a ground-based sound generator. These beams are transformed into atmospheric acoustic gravity waves (AGWs), which have parameters that enable them to penetrate to the altitudes of the ionospheric E and F regions where they influence the electron concentration of the ionosphere. Acoustic waves are generated by the ground-based parametric sound generator (PSG) at the two close frequencies. The main idea of the experiment is to design the output parameters of the PSG to build a cascade scheme of nonlinear wave frequency downshift transformations to provide the necessary conditions for their vertical propagation and to enable penetration to ionospheric altitudes. The PSG generates sound waves (SWs) with frequencies f1 = 600 and f2 = 625 Hz and large amplitudes (100–420 m s−1). Each of these waves is modulated with the frequency of 0.016 Hz. The novelty of the proposed analytical–numerical model is due to simultaneous accounting for nonlinearity, diffraction, losses, and dispersion and inclusion of the two-stage transformation (1) of the initial acoustic waves to the acoustic wave with the difference frequency Δf = f2 − f1 in the altitude ranges 0–0.1 km, in the strongly nonlinear regime, and (2) of the acoustic wave with the difference frequency to atmospheric acoustic gravity waves with the modulational frequency in the altitude ranges 0.1–20 km, which then reach the altitudes of the ionospheric E and F regions, in a practically linear regime. AGWs, nonlinearly transformed from the sound waves, launched by the two-frequency ground-based sound generator can increase the transparency of the ionosphere for the electromagnetic waves in HF (MHz) and VLF (kHz) ranges. The developed theoretical model can be used for interpreting an active experiment that includes the PSG impact on the atmosphere–ionosphere system, measurements of electromagnetic and acoustic fields, study of the variations in ionospheric transparency for the radio emissions from galactic radio sources, optical measurements, and the impact on atmospheric aerosols. The proposed approach can be useful for better understanding the mechanism of the acoustic channel of seismo-ionospheric coupling.

A Simple Computational Tool for Studying Acoustic Waves in Nonlinear Medium

2017 ◽  
Author(s):  
Nirmal J. Nair ◽  
Utsav Shah
Keyword(s):  
Acoustic Wave ◽  
Acoustic Waves ◽  
Nonlinear Medium ◽  
Numerical Scheme ◽  
Nonlinear Acoustics ◽  
Ultrasonic Waves ◽  
The Self ◽  
Sound Waves ◽  
Computational Tool ◽  
Nonlinear Acoustic

The behaviour of acoustic waves in nonlinear medium is well established in literature. But there is a need of a simple computational tool through which practical problems pertaining to nonlinear acoustics can be treated with minimum effort and expense. Additionally, visualization of nonlinear acoustic waves can be useful towards the applications of acoustic diodes and ultrasonic waves. To address this issue, we have developed a numerical scheme which effectively captures the self-distortion mechanism of acoustic wave in nonlinear medium and the consequential generation of higher harmonics. Additionally, the effects of increasing non-linearity constant of the medium and amplitude of sound waves on distortion of the waveform is studied.

scholarly journals Formation of a Complex Topologies of SAW-Based Inertial Sensors by Laser Thin Film Local Evaporation

Micromachines ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 10
Author(s):  
Alexander Kukaev ◽  
Dmitry Lukyanov ◽  
Denis Mikhailenko ◽  
Daniil Safronov ◽  
Sergey Shevchenko ◽  
...  
Keyword(s):  
Thin Film ◽  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Acoustic Waves ◽  
Inertial Sensors ◽  
Surface Acoustic Waves ◽  
Sensing Element ◽  
Small Series ◽  
Evaporation Technique ◽  
Photolithography Process

Originally, sensors based on surface acoustic waves are fabricated using photolithography, which becomes extremely expensive when a small series or even single elements are needed for the research. A laser thin film local evaporation technique is proposed to substitute the photolithography process in the production of surface acoustic wave based inertial sensors prototypes. To estimate its potential a prototype of a surface acoustic wave gyroscope sensing element was fabricated and tested. Its was shown that the frequency mismatch is no more than 1%, but dispersion of the wave on small inertial masses leads to a spurious parasitic signal on receiving electrodes. Possible ways of its neglecting is discussed.

scholarly journals Ultrasonic Waves in Bubbly Liquids: An Analytic Approach

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1309
Author(s):  
P. R. Gordoa ◽  
A. Pickering
Keyword(s):  
Mathematical Model ◽  
Partial Differential Equations ◽  
Differential Equations ◽  
Acoustic Waves ◽  
Elliptic Functions ◽  
Coupled System ◽  
Ultrasonic Waves ◽  
Partial Differential ◽  
Special Cases ◽  
Spherical Bubbles

We consider the problem of the propagation of high-intensity acoustic waves in a bubble layer consisting of spherical bubbles of identical size with a uniform distribution. The mathematical model is a coupled system of partial differential equations for the acoustic pressure and the instantaneous radius of the bubbles consisting of the wave equation coupled with the Rayleigh–Plesset equation. We perform an analytic analysis based on the study of Lie symmetries for this system of equations, concentrating our attention on the traveling wave case. We then consider mappings of the resulting reductions onto equations defining elliptic functions, and special cases thereof, for example, solvable in terms of hyperbolic functions. In this way, we construct exact solutions of the system of partial differential equations under consideration. We believe this to be the first analytic study of this particular mathematical model.

Linear and Nonlinear Analysis of Additively Manufactured Material With Different Porosity Induced by Varying Material Printing Speed Using Guided Acoustic Waves

2021 ◽  
Author(s):  
SeHyuk Park ◽  
Hamad Alnuaimi ◽  
Anna Hayes ◽  
Madison Sitkiewicz ◽  
Umar Amjad ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Nonlinear Analysis ◽  
Lead Zirconate Titanate ◽  
Acoustic Waves ◽  
Scanning Speed ◽  
Lead Zirconate ◽  
Nonlinear Ultrasonic ◽  
Scan Speed ◽  
Linear And Nonlinear ◽  
Characterization Of Materials

Abstract Guided acoustic wave based techniques have been found to be very effective for damage detection, and both quantitative and qualitative characterization of materials. In this research, guided acoustic wave techniques are used for porosity evaluation of additively manufactured materials. A metal 3D printer, Concept Laser Mlab 200 R Cusing™, is used to manufacture 316L additively manufactured (AM) stainless steel specimens. Two levels of porosity are investigated in this study, which was controlled by a suitable combination of scan speed and laser power. The sample with lower level of porosity is obtained with a low scanning speed. Lead Zirconate Titanate (PZT) transducers are used to generate guided acoustic waves. The signal is excited and propagated through the specimens in a single sided transmission mode setup. Signal processing of the recorded signals for damage analysis involves both linear and nonlinear analyses. Linear ultrasonic parameters such as the time-of-flight and magnitude of the propagating waves are recorded. The nonlinear ultrasonic parameter, the Sideband Peak Count Index (SPC-I) is obtained by a newly developed nonlinear analysis technique. Results obtained for both specimens are analyzed and compared using both linear and nonlinear ultrasonic techniques. Finally, the effectiveness of SPC-I technique in monitoring porosity levels in AM specimens is discussed.

scholarly journals Modelling damped acoustic waves by a dissipation-preserving conformal symplectic method

2017 ◽  
Vol 473 (2199) ◽  
pp. 20160798 ◽  
Author(s):  
Wenjun Cai ◽  
Huai Zhang ◽  
Yushun Wang
Keyword(s):  
Wave Equation ◽  
Acoustic Wave ◽  
Acoustic Waves ◽  
Conservation Law ◽  
Heterogeneous Media ◽  
Numerical Dispersion ◽  
Discrete Version ◽  
Symplectic Method ◽  
Ode System ◽  
Strang Splitting

We propose a novel stable and efficient dissipation-preserving method for acoustic wave propagations in attenuating media with both correct phase and amplitude. Through introducing the conformal multi-symplectic structure, the intrinsic dissipation law and the conformal symplectic conservation law are revealed for the damped acoustic wave equation. The proposed algorithm is exactly designed to preserve a discrete version of the conformal symplectic conservation law. More specifically, two subsystems in conjunction with the original damped wave equation are derived. One is actually the conservative Hamiltonian wave equation and the other is a dissipative linear ordinary differential equation (ODE) system. Standard symplectic method is devoted to the conservative system, whereas the analytical solution is obtained for the ODE system. An explicit conformal symplectic scheme is constructed by concatenating these two parts of solutions by the Strang splitting technique. Stability analysis and convergence tests are given thereafter. A benchmark model in homogeneous media is presented to demonstrate the effectiveness and advantage of our method in suppressing numerical dispersion and preserving the energy dissipation. Further numerical tests show that our proposed method can efficiently capture the dissipation in heterogeneous media.

scholarly journals Analysis of Propagation and Distribution Characteristics of Leakage Acoustic Waves in Water Supply Pipelines

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5450
Author(s):  
Yunfei Li ◽  
Yang Zhou ◽  
Ming Fu ◽  
Fan Zhou ◽  
Zhaozhao Chi ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Water Supply ◽  
Acoustic Waves ◽  
Simulation Analysis ◽  
Acoustic Signals ◽  
Detection Methods ◽  
Acoustic Analogy ◽  
Acoustic Wave Propagation ◽  
Source Characteristics ◽  
Water Supply Pipeline

Leakage detection methods based on the analysis of leakage acoustic signals provide an effective technical approach for detecting small leaks in water supply pipelines. From a technical perspective, the study of the propagation characteristics of acoustic waves generated by the leakage in the water supply pipeline is necessary for detecting the leak location on the basis of acoustic signals. In this study, a 3D transient leakage acoustic wave propagation equation was derived by combining the principles of fluid dynamics and Lighthill acoustic analogy theory. The propagation of the leakage-induced noise in water supply pipeline was modelled theoretically. We simulated the propagation of a leakage acoustic wave under different conditions for different target scenarios encountered in actual pipeline inspections. Specifically, we analysed the effect of different factors, such as the pipe size and acoustic source characteristics, on acoustic propagation. Finally, the simulated experiments were practically performed using a self-designed simulated water supply pipeline and self-developed spherical water supply pipeline detector to validate the simulation analysis. The results of this study provide a theoretical guidance and basis for the analysis of characteristics of leakage acoustic wave signals and the recognition of leakage conditions in water supply pipelines.

scholarly journals Моделирование проводимости Капицы через шероховатые интерфейсы между твердыми телами

2021 ◽  
Vol 63 (7) ◽  
pp. 982
Author(s):  
Б. Лю ◽  
В.И. Хвесюк ◽  
А.А. Баринов
Keyword(s):  
Experimental Data ◽  
Theoretical Prediction ◽  
Transmission Coefficient ◽  
Wide Temperature Range ◽  
Acoustic Waves ◽  
Theoretical Method ◽  
Interface Roughness ◽  
Kapitza Conductance ◽  
Acoustic Mismatch ◽  
The Difference

In this work, we have formulated and solved the problem of determining the Kapitza conductance across the interface between two solids, taking into account the interface roughness. We use a modified acoustic mismatch model (AMM). The difference from the classic model is that the dispersion properties of acoustic waves are considered. A significant advantage of this model is that the theoretical prediction agrees well with experimental data over a wide temperature range: from 30K to more than 300K. Finally, a theoretical method with the statistical distribution of roughness profiles is used to determine the energy transmission coefficient across the interface.

scholarly journals Non-local dispersion and ultrasonic tunneling in concentrationally graded solids

2019 ◽  
Vol 21 (1) ◽  
pp. 54-62
Author(s):  
A. B. Shvartsburg ◽  
M. D. Malinkovich ◽  
A. M. Kislyuk
Keyword(s):  
Acoustic Waves ◽  
Travelling Waves ◽  
Ultrasonic Waves ◽  
Formal Similarity ◽  
Constant Elasticity ◽  
Transmittance Spectra ◽  
Local Dispersion ◽  
Total Transmission ◽  
Non Local ◽  
Spectral Ranges

The non-local dispersion of longitudinal ultrasonic waves is shown to appear in the heterogeneous solids due to continuous spatial distributions of their density and/or elasticity (gradient solids). This dispersion gives rise to the diversity of ultrasonic transmittance spectra, including the broadband total reflectance plateau, total transmission and tunneling spectral ranges. The ultrasonic wave fields in gradient solids, formed by interference of forward and backward travelling waves as well as by evanescent and antievanescent modes are examined in the framework of exactly solvable models of media with continuously distributed density and elasticity. Examples of transmittance spectra for both metal and semiconductor gradient structures are presented, and the generality of concept of artificial non-local dispersion for gradient composite materials is considered. It should also be noted that the wave equation for acoustic waves in gradient media with a constant elasticity modulus and a certain predetermined density distribution reduces to an equation describing the electromagnetic wave propagation in transparent dielectric media. This formal similarity shows that the concept of nonlocal dispersion is common for both optical and acoustic phenomena, which opens the way to the direct use of physical concepts and exact mathematical solutions, developed for gradient optics, to solve the corresponding acoustic problems.

Sign in / Sign up

Export Citation Format

Share Document