Propagation Characteristics Of Acoustic Waves Research Articles

Quantum Electron Acoustic Solitons and Double Layers with κ-deformed Kaniadakis Distributed Electrons

The present investigation is dedicated to the study of propagation characteristics of electron acoustic (EA) waves and double layers in the quantum plasma system containing inertialess hot electrons and inertial cold electrons with stationary ions forming the charge neutralizing background. It is assumed that hot electrons follow κ-deformed Kaniadakis distribution as governed by the parameter κ. Using the appropriate stretched coordinates and reductive perturbation method (RPM) the Korteweg-de Vries (KdV) and modified KdV (mKdV) equations have been derived. For the sake of analysis, a limit of range of deformation parameter (κ) has been set as -0.4≤κ≤0.4. For the defined range, it has been observed that plasma system supports rarefactive solitary structures. The amplitude and width of KdV soliton have been significantly affected by the quantum effects and remains unaffected by the deformation parameter (κ). The analysis was further extended to the derivation of mKdV equation to investigate the existence of small amplitude double layers (DLs). Only negative potential DLs are found to exist whose dynamics significantly depends on deformation parameter (κ), quantum effects (H) and hot to cold electron density ratio (α). The outcome of the present discourse may be helpful to understand the use of generalized entropies in the environment of plasma physics.

Nonextensive approach to the effect of electron trapping in the presence of quantizing magnetic field on the propagation of ion acoustic waves

Ion acoustic waves (IAWs) are studied for degenerate trapped electron and non-degenerate ion plasma in the presence of quantizing magnetic field in the Tsallis framework. The presence of a magnetic field induces a trapping effect on degenerated electrons, which is studied using the generalized form of the Fermi–Dirac in the non-extensive framework. An appropriate new electron density is reformulated and reexamined in this statistics. The new expression for electron density is used to study the propagation of ion acoustic waves. The linear dispersion relation for IAWs is derived in the presence of the quantizing magnetic field and a small finite temperature in the framework of q-statistics, there influence on the propagation characteristics of the linear ion acoustic wave is discussed. In arbitrary amplitude, we use the Sagdeev potential showing that rarefactive and compressive ion acoustic solitary wave can exist simultaneously under certain conditions of temperature T, quantizing magnetic field η and the entropic index q. In addition, to study the dynamics of small but finite amplitude ion Acoustics solitary waves. Using the reductive perturbation technique the Korteweg de-Vries equation is established. Our results show that both rarefactive and compressive solitary waves may coexist in a certain range of plasma parameters.

Propagation characteristics of low-frequency acoustic wave in full waveguide of shallow water based on time-domain finite element method

In order to clarify the propagation mechanism and characteristics of low-frequency sound signals in shallow sea with elastic bottom, using the Time-domain Finite Element Method (TDFEM), a time-domain numerical calculation model of the low-frequency sound field in shallow sea full-waveguide under the action of a point sound source is established. With this model, The influence of seabed acoustic parameters’ and seabed topography’ changes on the sound propagation characteristics in full-waveguide is simulated and analyzed. The results show that when there is a shear wave effect on the seabed, low-frequency sound waves will excite the Scholte wave propagating on the bottom boundary of the seabed. The greater the seabed acoustic impedance, the faster the excited Scholte wave velocity and the large the amplitude. At the same time, there will be acoustic energy leakage phenomenon in the inclined seabed.

The Sensitive Element of Acoustic Sensor on Circular Polarized Waves: From Theoretical Considerations towards Perspective Rotation Rate Sensors Design.

In this paper, the perspectives of using the features of acoustic wave propagation to design rotation rate sensors (RRS) are discussed. The possibility of developing the solid-state sensitive elements (SE) of RRS on acoustic waves of circular polarization is shown. The theoretical basis of bulk acoustic wave propagation under rotation is given. The direct excitation of circularly polarized acoustic wave (CPAW) is considered, the design of the CPAW emitting transducer is offered. The results of experimental studies that indicated the circular nature of the particle motions in the radiated wave are discussed. The principally new concept of the RRS SE design on CPAW, being able to operate under high vibration and acceleration, is proposed. The experimental results revealed a high correlation with theoretical and numerical predictions and confirmed RRS on CPAW operability.

Low-Loss 5-GHz First-Order Antisymmetric Mode Acoustic Delay Lines in Thin-Film Lithium Niobate

In this work, we present the low-loss acoustic delay lines (ADLs) at 5 GHz, using the first-order antisymmetric (A1) mode in 128° Y-cut lithium niobate thin films. The ADLs use a single-phase unidirectional transducer (SPUDT) design with a feature size of quarter acoustic wavelength. The design space is analytically explored and experimentally validated. The fabricated miniature A1 ADLs with a feature size of show a high operating frequency at 5.4 GHz, a minimum insertion loss (IL) of 3 dB, a fractional bandwidth (FBW) of 1.6%, and a small footprint of 0.0074 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The low IL and high operating frequency have significantly surpassed the state-of-the-art performance of ADLs. The propagation characteristics of A1 acoustic waves have also been extracted. The demonstrated designs can lead to low-loss and high-frequency transversal filters for future 5G applications in the sub-6-GHz bands.

Numerical Simulation Research on Reflected Wave Characteristics of Oil and Gas Well Coupling

In order to analyse and identify the reflection morphology of the coupling reflected wave in the oil jacket annulus and to clarify the influences of different factors on the coupling reflection waveform, the COMSOL finite element analysis software is used to conduct a numerical simulation study on the above situation, and the response characteristics are obtained by calculation. In this paper, different signal sources are used to research the three-dimensional propagation characteristics of acoustic wave when it meets the coupling in the annular space. Numerical simulations are carried out for different coupling thicknesses, different coupling radii, and different oil casing annulus pressures to analyse their influences on the waveform of coupling wave. The results showed that when the polarity of the signal source was positive (negative), the coupling reflection signal was positive (negative) at first and then negative (positive). When the signal source is a positive-negative superimposed source, the first peak polarity of the coupling reflection signal is consistent with the signal source. The reflected signal is superimposed by the response generated by the positive and negative signal sources, respectively. With the increase of the coupling radius, the morphology of coupling wave remains unchanged while its reflected wave amplitude increases nonlinearly with the increase of the coupling radius; with the increase of the oil casing annulus pressure, the morphology of coupling wave does not change, but the amplitude of the reflected wave increases linearly with the increase of the pressure; as the thickness of the coupling increases, the peak-to-peak spacing of the coupling reflection wave becomes larger and the positive and negative peaks separate. The research results can provide theoretical basis and reference standards for the analysis of the characteristics of the signals received by the actual fluid level detector, the performance verification of the echo signal processing method and the correct identification of the dynamic fluid level position.

Effects of bedding structures on the propagation characteristics of acoustic waves in shales at operating frequencies of acoustic logging

Acoustic characteristics measured by acoustic logging are usually used to estimate the structures and mechanical properties of rock materials. However, it is problematic to measure acoustic characteristics of shales because of their structural anisotropy caused by the bedding structures. This study focused on the effects of bedding structures on the acoustic characteristics of shales at operating frequencies of acoustic logging. A numerical model was first established to estimate the acoustic characteristics of shales based on the viscoelastic theory. Then, acoustic transmission experiments were conducted to examine the acoustic characteristics of shales with different bedding angles. The model calculations were compared with experimental results, showing good agreement. Based on the model, the effects of the angle, density, and thickness of bedding planes on the acoustic characteristics of shales at operating frequencies of acoustic logging were analyzed in detail. The results indicate that the wave velocity and main amplitude increased with increasing bedding angle whereas the attenuation coefficient decreased. The wave velocity monotonically decreased with an increase in the bedding density and thickness when the acoustic waves were transmitted through the shale model, but the attenuation of acoustic waves exhibited an opposite trend with the slope. In comparison, the dominant frequency was relatively stable with variations in the bedding structures. In general, the effect of bedding thickness on the acoustic characteristics of shales was smaller than those of the bedding angle and bedding density. The findings of this study can be beneficial for the accurate measurement of shale acoustic characteristics in acoustic logging.

Influences of bedding characteristics on the acoustic wave propagation characteristics of shales

Abstract The acoustic response characteristics of shales were investigated by the acoustic transmission experiment, which is the basis of solving geological and engineering problems using the seismic or logging information during the process of the exploration and development of shale gas reservoirs. Based on the theory of acoustic wave and the background of acoustic transmission experiment, the initial condition, vibration source condition, boundary condition and stability condition were constructed, and the numerical simulation of acoustic transmission experiment of shales were completed through Matlab programming. The results show that under the same bedding angle, the acoustic time and attenuation coefficient of shales shown positive correlation with the bedding density; whereas under the same bedding density, the variation laws of the acoustic time and the attenuation coefficient of shales were more complex with the change of the bedding angle, that is, the acoustic time and attenuation coefficient of shales increased first, then decreased and then increased again with the increase of the bedding angle.

Numerical simulation of reflected wave characteristics in oil wells measured by Acoustic method

In order to analyze and identify the corrosion of the inner interface of the coupling, perforating and casing, or the collapse and depression of the casing, as well as the reflection form of the dynamic liquid level, the COMSOL finite element analysis software was used to carry out numerical simulation research on the above situation, and its response characteristics were obtained through calculation. In this paper, three-dimensional propagation characteristics of acoustic waves in the annulus of the oil jacket were studied using signal sources of different polarities. The results showed that when the polarity of the signal source was positive (negative), the coupling reflection signal was first positive (negative) and then negative (positive), and the perforation reflection signal was first negative and then positive (positive then negative). The waveform of the reflection signal in the case of corrosion or casing collapse was consistent with the waveform of the perforation reflection signal; the reflection signal of the moving surface was of the same polarity as the emission signal source. When the signal source was a positive-negative superimposed source, the conclusion obtained by applying the above-mentioned positive (negative) polarized signal source was based on the polarity of the first peak of the superposed source. The research results can provide strong support for the popularization and improvement of related theories, and correct reference standards for the performance verification of echo processing methods, as well as important theoretical basis for the correct identification of echo positions on the Dynamic fluid interface.

Dipolar and Kelvin-Stuart’s cat’s eyes vortices in magnetoplasmas with non-Maxwellian electron distribution

Linear and nonlinear propagation characteristics of drift ion acoustic waves are analyzed in an inhomogeneous plasma comprising of warm ions having shear flow parallel to the magnetic field and electrons that are followed by a distribution which is dictated by spectral indices, $r$ and $q$ in low and high phase density regions. In the linear regime, the dispersion relation of the drift-ion acoustic wave is derived and the condition for the onset of shear flow instability is presented. It is found that condition for the emergence of shear flow instability gets modified by generalized $(r,q)$ distribution and ion to electron temperature ratio. In the nonlinear regime, vortex formation with non-Maxwellian electron distribution is investigated and the effects of low and high energy electrons in this context are explored in detail. Interestingly, it is found that unlike the dipolar vortices, the electrons in the high phase space density regions do not significantly affect the Kelvin-Stuart’s cat’s eyes structures, however, the converse is true for the electrons belonging to the regions of low phase space density. Estimates of the size of these vortex structures in space plasmas are also given where the distribution function presented here is frequently encountered.

5-GHz Antisymmetric Mode Acoustic Delay Lines in Lithium Niobate Thin Film

We present the first group of acoustic delay lines (ADLs) at 5 GHz, using the first-order antisymmetric (A1) mode in Z-cut lithium niobate thin films. The demonstrated ADLs significantly surpass the operation frequency of the previous works with similar feature sizes, because of its simultaneously fast phase velocity, large coupling coefficient, and low-loss. In this work, the propagation characteristics of the A1 mode in lithium niobate is analytically modeled and validated with finite element analysis. The design space of A1 ADLs is then investigated, including both the fundamental design parameters and those introduced from the practical implementation. The implemented ADLs at 5 GHz show a minimum insertion loss of 7.94 dB, an average IL of 9.1 dB, and a fractional bandwidth around 4%, with delays ranging between 15 ns to 109 ns and the center frequencies between 4.5 GHz and 5.25 GHz. The propagation characteristics of A1 mode acoustic waves have also been extracted for the first time. The A1 ADL platform can potentially enable wide-band high-frequency passive signal processing functions for future 5G applications in the sub-6 GHz spectrum bands.

Simulation and detection of blockage in a pipe under mean fluid flow using acoustic wave propagation technique

Pipeline blockage can result in the reduction of system carrying capacity, energy and resource wastage, and potential increase in the probability of occurrence of environmental and health problems. The primary purpose of this paper is to demonstrate a methodology to simulate acoustic wave propagation (AWP) in partially blocked fluid-filled pipes with flow under different flow velocities. This was achieved by using computational fluid dynamics (CFD) software in conjunction with an external user-defined function (UDF) file, which introduces compressibility effect into the CFD solution. The use of finite element analysis (FEA) to simulate AWP in fluid-filled pipelines with blockage has been previously reported without flow. In this paper, both CFD and FEA techniques were used to simulate the AWP in air-filled pipelines without mean flow. However, it is shown that only the CFD technique could be used to simulate the AWP in air-filled pipelines with mean flow. The secondary purpose of the paper is to use the simulated acoustic waveforms to illustrate a blockage identification procedure for detection, localisation, and sizing of blockages in fluid-filled pipes using time of flight (ToF) methodology. It is shown that the ToF accurately detects and locates blockages in blocked pipelines. The errors in the localisation of blockages were less than 4%. Furthermore, the effects of blockage size and the mean flow velocity on the AWP characteristics are established. It is shown that both the size of the blockage in a pipe and the mean flow velocity affect the pressure amplitude of the transmitted and reflected waveforms.

Influence of Moisture of Wheat on Acoustic Wave Propagation Characteristics

HighlightsA novel measuring device was developed for the propagation constant of acoustic waves in grain.Increase in moisture of wheat from 1.1% to 7.8% (wet basis) decreased the wave velocity and increased the attenuation coefficient.Increase in moisture of wheat from 7.8% to 21.2% increased the wave velocity and decreased the attenuation coefficient.Using the Johnson-Champoux-Allard (JCA) model and particle swarm optimization (PSO) algorithm, the influence of moisture on the pore structure in wheat was characterized.Abstract. Acoustic methods have been widely used for the measurement of grain moisture content and temperature as well as for detecting the presence of insects in grain. Therefore, this study was conducted to understand the influence of wheat moisture content on acoustic wave propagation characteristics. A novel device was developed for measuring the acoustic wave propagation constant. The propagation constants of 12 samples of wheat were measured, with each sample having a different moisture content in the range from 1.1% to 21.2% (wet basis). The results showed that the acoustic wave velocity decreased slightly with an increase in moisture from 1.1% to 7.8%, while the attenuation coefficient increased slightly. When the moisture increased from 7.8% to 21.2%, the velocity increased gradually, while the attenuation coefficient decreased. A quadratic equation described the results well. In addition, a Johnson-Champoux-Allard (JCA) model was adopted to study the influence of moisture on the pore structure of wheat samples. With the increase in moisture from 1.1% to 21.2%, the average radius of interconnection between two adjacent pores decreased from 0.275 to 0.262 mm at moisture below 7.8% and then increased to 0.304 mm, and the average radius of the pores decreased from 0.773 to 0.481 mm at moisture below 7.8% and then increased to 1.2 mm. Keywords: Acoustic standing wave tube, JCA model, Moisture content, Propagation constant, PSO algorithm, Wheat.

고해상도 수치기법을 이용한 플래핑 날개 주위 비정상 아음속 유동해석

Many numerical and experimental researches have been done for the unsteady flow around a flapping airfoil. The main research topics are vortex shedding, dynamic stall phenomenon, and MAV''s lift and thrust generation for the flow over a flapping airfoil. Although many researches have been studied to analyze the flow for the variation of frequency and amplitude, much research is still needed. In this study, thrust generation, wake structures, and acoustic wave propagation characteristics were studied for a flapping airfoil. The governing equation was the Navier-Stokes equation with LES turbulence model, and the Optimized High-Order Compact (OHOC) scheme and 4th order Runge-Kutta method were used. The Mach number and Reynolds number were 0.3 and 1000, respectively. The analysis of mean lift and drag coefficients showed the thrust generation characteristics according to the phase angle and the reduced frequency. The wake vortex shedding and propagation characteristics of acoustic waves could be simulated using the high order method.

Study of Dust Acoustic Wave Propagation in a Lorentzian Dusty Plasma in Presence of Secondary Electron Emission

In this paper, we have investigated the effect of secondary electron emission on the propagation characteristics of linear dust acoustic waves in dusty plasmas consisting of suprathermal inertialess primary electrons, secondary electrons, Boltzmann distributed ions, and negatively charged inertial dust grains. The suprathermal electrons are assumed to follow kappa velocity distribution. We have derived the linear dispersion relation and shown that real and imaginary frequencies of the waves are influenced by the strength of secondary electron emission as well as suprathermal electron population.

Investigation on Characteristics of Longitudinal Acoustic Wave Propagation in Coal Mine Drill Rods

In order to investigate the feasibility of drill rods used for wireless data transmission in coal mine, the properties of longitudinal acoustic wave propagation in drill string are studied. The results show that: the spectral properties of drill string for coal mine show like a comb filter with wide passbands; when single drill rod become longer, numbers of passbands become more, the width of total passband become narrower; bigger diameter of drill rod makes the width of total passband narrower and amplitudes lower; for integral type and joint-connection type drill rod with same diameter and length, they have little difference in total passband width; the drill strings with different total length have almost same spectral characteristics. In the drill strings investigated, the drill strings composed by drill rods with 42mm diameter and 1m length has the widest passband which occupy 70% of the whole frequency scope. All results indicate that drill rods can be used as channel in data transmission in coal mine gallery.

AMPLITUDE ATTENUATION LAWS OF ACOUSTIC EMISSION WAVES IN PLATE STRUCTURES

Although acoustic emission technology has been used in the nondestructive testing of various plate structures, its further application and development remain limited because the laws governing the amplitude attenuation of acoustic emission waves in plate structures remain unclear. This study aimed to reveal the amplitude attenuation laws of acoustic emission waves in plate structures. Thus, in this study, the traditional model of amplitude attenuation, which is in the form of an exponential function, was improved in reference to cylindrical waves, and an amplitude attenuation model in the form of a power function suitable for plate structures was proposed. Moreover, an experimental system for the attenuation of acoustic emission waves in aluminum alloy plates was established to experimentally verify the proposed model. Finally, the amplitude attenuation laws of acoustic emission waves within the full field, near field, and far field of plate structures were discussed. Results show that the amplitude attenuation laws of acoustic emission waves within the full field, near field, and far field of plate structures all conform to the power function model and gradually reduce as propagation distance increases. In addition, the improved amplitude attenuation model better corresponds with the actual amplitude attenuation trend within the near-field range of the acoustic emission source than other forms of amplitude attenuation models. Specifically, the traditional model of amplitude attenuation model agrees with the actual attenuation laws of acoustic emission waves only within the far-field range of the acoustic emission source. The results of this study provide valuable references for the profound analysis of the propagation characteristics of acoustic emission waves in plate structures and will help promote the development and application of acoustic emission technology. Keywords: Acoustic emission waves, Amplitude, Attenuation, Laws, Plate

3P3-8 Analysis and verification of surface acoustic wave propagation characteristics in cover glass/liquid layer/LiNbO3 structure

3P3-8 Analysis and verification of surface acoustic wave propagation characteristics in cover glass/liquid layer/LiNbO₃ structure

Effects of Central Tube on Shape of Modal Duct of a Helicoid in a Simple Expansion Chamber

The shape of the modal duct of an acoustic wave propagating in a muffling system varies with the internal geometry. This shape can be either as a result of plane wave propagation or three-dimensional wave propagation. These shapes depict the distribution of acoustic pressure that may be used in the design or modification of mufflers to create resonance at cut-off frequencies and hence achieve noise attenuation or special effects on the output of the noise. This research compares the shapes of acoustic duct modes of two sets of four pitch configurations of a helicoid in a simple expansion chamber with and without a central tube. Models are generated using Autodesk Inventor modeling software and imported into ANSYS 18.2, where a fluid volume from the complex computer-aided-design (CAD) geometry is extracted for three-dimensional (3D) analysis. Mesh is generated to capture the details of the fluid cavity for frequency range between 0 and 2000Hz. After defining acoustic properties, acoustic boundary conditions and loads were defined at inlet and outlet ports before computation. Postprocessed acoustic results of the modal shapes and transmission loss (TL) characteristics of the two configurations were obtained and compared for geometries of the same helical pitch. It was established that whereas plane wave propagation in a simple expansion chamber (SEC) resulted in a clearly defined acoustic pressure pattern across the propagation path, the distribution in the configurations with and without the central tube depicted three-dimensional acoustic wave propagation characteristics, with patterns scattering or consolidating to regions of either very low or very high acoustic pressure differentials. A difference of about 80 decibels between the highest and lowest acoustic pressure levels was observed for the modal duct of the geometry with four turns and with a central tube. On the other hand, the shape of the TL curve shifts from a sinusoidal-shaped profile with well-defined peaks and valleys in definite multiples of π for the simple expansion chamber, while that of the other two configurations depended on the variation in wavelength that affects the location of occurrence of cut-on or cut-off frequency. The geometry with four turns and a central tube had a maximum value of TL of about 90 decibels at approximately 1900Hz.

Realization of complex curved waveguide based on local resonant 3D metamaterial

To overcome the negative impact of diffraction effect on the transmission wave front at the bend and to improve the transmission efficiency of acoustic wave in the bend waveguide, the finite element method by COMSOL was used to simulate the propagation characteristics of acoustic wave in the structure of bending acoustic waveguide, based on local resonance acoustic metamaterials. Specifically, the vibration mechanism of three-dimensional (3D) component locally resonant phononic crystals was presented, and the acoustic metamaterial models of M-shaped, L-shaped and S-shaped bent waveguides were constructed on the basis of the protocells. The local resonance between the acoustic wave and the protocells in the waveguide model was investigated, in order to produce the nondestructive bending propagation effect of the acoustic wave. The results of finite element analysis show that the plane acoustic waves incident from the M-shaped, L-shaped and S-shaped bending waveguide model will propagate directionally along the model structure after being controlled at the resonance frequency. These results confirm the flexibility and feasibility of the bending acoustic waveguide model designed by the local resonance acoustic metamaterials. In addition, the acoustic waveguide model in long-distance special environment was designed and the low loss transmission of acoustic signal was implemented. This study provides a new solution for engineering applications, such as ultrasonic signal detection and underwater acoustic communication transmission.