Acoustic Field Parameters Research Articles

Optimization Analysis of Acoustic Field Parameters in Phased Array Ultrasonic Transducers

Optimization Analysis of Acoustic Field Parameters in Phased Array Ultrasonic Transducers

Local control of magnetic microbubble behavior by magnetic field and pulsed ultrasound

The localization of magnetic microbubbles (MMBs) to a target site has been shown to be essential to their efficacy in therapeutic applications such as targeted drug delivery and gene therapy. In this work, the MMBs’ dynamic equations of vibration, horizontal and vertical motion in a fluid-filled tube, subject to a magneto-acoustic complex field, are established by Lagrange method. The responses and capture efficiency under three ultrasonic pulses waveform in a magnetic field are numerically analyzed. The regulation effects of the external field are observed by experiments. The results show that the transport behavior is influenced by bubble size, original position, liquid flow rate, tube diameter, parameters of acoustic and magnetic field. For the same acoustic parameters, square wave pulse can make stronger vibrate compared with cosine wave and sawtooth wave, which pushes MMBs closer to the magnet. In addition, high frequency and large amplitude pulse are benefit to translation, and increasing the cycle number in a single pulse can also promote translation. In practical applications, variable parameters such as bubble speed and magnet length can be used to improve the capture efficiency. The observations of high-speed camera are consistent with the prediction of theoretical model, which indicates the model is mostly correct.

Radiation processes on acoustic superlattices

We describe several radiation processes in media excited by volume and surface acoustic waves. They include the Cherenkov and transition radiations on acoustic superlattices, transition radiation on an interface with a dynamical periodic structure, the Smith-Purcell radiation on surface waves, bremsstrahlung of high-energy electrons and the creation of electron-positron pairs by high energy photons in crystals in the presence of hypersonic waves. The conditions on the parameters of acoustic fields are specified under which their influence is essential. All these considerations show that the acoustic waves can serve as an efficient mechanism to control the parameters of various kinds of radiation processes.

Translation of interacting cavitation bubble in a plane acoustic field

In a plane acoustic field, a model involving the radial and translational motions of bubble is derived, which is used to numerically investigate the translation of two interacting spherical cavitation bubbles. For the smaller initial distance between bubble centers, we investigate the dynamics of two bubbles, and find that they could come into contact but the velocities of closing to each other are different when the equilibrium radius is different. The results show that when the wavelength of plane acoustic field is much larger than the initial distance, the bubbles are approximately pulsating in phase. Moreover, the velocity of contact process of two bubbles can be changed by adjusting the parameters of plane acoustic field. For increasing in the initial distance, the bubbles would present two translation motions: close to each other for the pulsating in phase and away from each other for the pulsating out of phase, which could be verified by calculating the secondary Bjerknes force. Meanwhile, the larger the initial distance, the smaller the secondary Bjerknes force value is. Understanding the translation of bubble is of great significance for helpful explaining formation of streamer structures in ultrasonic cavitation.

Experimental and numerical study on the acoustic coagulation of charged particles

Coagulation technology is widely used as a dust removal technology pre-treatment. The mechanism of particle coagulation and charging under the coupling of the electric field and the acoustic field is investigated in this paper. The movement law of the acoustic field waveform, sound pressure level and acoustic field flow rate parameters on the particles are analyzed numerically using COMSOL Multiphysics software, and the operating parameters for the best coagulation effect of charged particles are obtained through experimental studies. The results show that the higher the supply voltage, the more the particles are charged and the better the particle coagulation effect. The higher the sound pressure level, the better the particle coagulation effect. The acoustic frequency is not linearly related to the particle coagulation efficiency. An optimal operating parameter is obtained. The acoustic and electric field coupling resulted in a particle reduction rate of 0.62 and a significant particle coagulation effect. • The mechanism of particle coagulation under the coupling effect of acoustic and electric fields is studied. • The effect of different acoustic field parameters on the particle motion pattern in the furnace is simulated. • The optimal acoustic field parameters are obtained. • The particle reduction rate reaches 0.62.

Focused ultrasound neuromodulation on a multiwell MEA

BackgroundMicroelectrode arrays (MEA) enable the measurement and stimulation of the electrical activity of cultured cells. The integration of other neuromodulation methods will significantly enhance the application range of MEAs to study their effects on neurons. A neuromodulation method that is recently gaining more attention is focused ultrasound neuromodulation (FUS), which has the potential to treat neurological disorders reversibly and precisely.MethodsIn this work, we present the integration of a focused ultrasound delivery system with a multiwell MEA plate.ResultsThe ultrasound delivery system was characterised by ultrasound pressure measurements, and the integration with the MEA plate was modelled with finite-element simulations of acoustic field parameters. The results of the simulations were validated with experimental visualisation of the ultrasound field with Schlieren imaging. In addition, the system was tested on a murine primary hippocampal neuron culture, showing that ultrasound can influence the activity of the neurons.ConclusionsOur system was demonstrated to be suitable for studying the effect of focused ultrasound on neuronal cultures. The system allows reproducible experiments across the wells due to its robustness and simplicity of operation.

Tools for Regulating Noise Loads from Automobile Urban Transport

A set of strategic directions in solving the problem of noise pollution of the environment in the city of Krasnoyarsk, the main source of which is urban transport, is proposed. Based on the results of full–scale studies and the use of system-analytical methods, the choice of residential zones of increased acoustic discomfort is made – areas of "old" buildings, where the layout of streets and buildings is not designed for modern noise loads from increasing traffic flow. Assessing and mapping of the noise fields in these areas during the day and night periods showed an excess of the norms. The factors of increasing the parameters of acoustic fields are revealed. Noise protection solutions for optimizing the existing transport infrastructure based on new environmental standards are proposed, their acoustic efficiency is evaluated.

Numerical investigation of particle deflection in tilted-angle standing surface acoustic wave microfluidic devices

• Numerical model developed for particle trajectories in acoustofluidic separation. • Effect of related parameters of acoustic and flow fields on trajectories is analyzed. • Two-stage separation demonstrated for exosome-sized particles from whole blood. • The model has potential for optimal design of acoustofluidic separation systems. The tilted-angle standing surface acoustic wave (taSSAW) microfluidic device has become a powerful tool for biosample separation due to its biocompatibility and non-contact, label-free, and high-efficiency nature. Studying and modeling particle deflection in a microfluid environment containing a taSSAW field is essential in the design of robust taSSAW-based microfluidic devices. Here, we present a numerical model taking into consideration fluid viscous drag force and the acoustic radiation force induced by scattering of acoustic waves for the study of particle deflection. The reliability of the model is validated by comparing our predictions with data from existing literature. In order to support our prediction experimentally, we fabricated a taSSAW microfluidic chip using 128° YX LiNbO 3 , and the deflection results for 3- and 7-μm polystyrene microspheres concur with the numerical estimation. The effects on particle deflection by parameters such as pre-focusing, pre-focusing width, average flow velocity, acoustic pressure amplitude, tilted angle, and surface acoustic wave frequency on particle deflection are then analyzed. This model could be used to optimize the design and better understand the mechanism of taSSAW microfluidic devices.

Vibrational behavior of coated microbubble in finite tube under magneto-acoustic composite field

The dynamic behavior of coated microbubble in a magneto-acoustic field is very significant for its application to therapy. In this paper, the radial vibration equation of microbubble is derived by placing the coated-microbubbles in a tube filled with magnetic fluid and considering the magnetic pressure on the magnetic fluid under the magneto-acoustic field. The dynamic equation is nondimensionalized by using characteristic quantities such as Weber number and Reynolds number. The effects of magnetic-acoustic field parameters and magnetofluid characteristics on the vibration behavior of the vibration system are analyzed by the Runge-Kutta method. The results show that the magnetic field can prevent the collapse and make bubble oscillate stably. When the acoustic field is constant, the magnetic field can stabilize the oscillation of the microbubble and increase the equilibrium radius of the oscillating microbubble. The stronger the magnetic field is, the more obvious the influence of magnetofluid magnetisability <i>χ</i><sub>m</sub> on the vibration of the microbubble is and the stronger the nonlinear of the transient response of the microbubble is when the magnetic field is larger. In addition, the larger acoustic field parameters will enhance the response of oscillating microbubble to magnetic field. The larger the magnetic field is, the weaker the influence of acoustic parameters on the oscillations of microbubble is. Also, the transient response of microbubble is obviously nonlinear, but the steady-state response keeps the reciprocating oscillation with small amplitude. It can be seen that the adjusting of the magneto-acoustic field is beneficial to realizing the stable oscillation of microbubble in the blood vessel and avoiding collapse.

Acoustic Determination of Properties Possessed by Porous Titanium

To impart the optimal structure to a powder material and promote high mechanical properties, the production process is to be monitored at each step using nondestructive methods. Acoustic methods are believed to be promising in this respect. The parameters of acoustic fields are influenced by many factors that determine the structure and properties of powder materials. A relevant task is to improve acoustic methods for the identification and use of this influence. A model material is taken as an example to show the capabilities of a nondestructive acoustic method relying on integrated measurement of the propagation velocities of longitudinal, transverse, and rod elastic waves in studying the patterns peculiar to the powder structurization at the molding and sintering stages. The following problems that can be solved using this method are considered and experimentally confirmed: identify how the properties of the starting powders influence the characteristics of the final material, monitor the compaction and contact formation processes in the material, and identify features of these processes, which are manifested as uneven distribution of properties over the material and aftereffects and are stepwise. Additional criteria are proposed to increase the reliability and descriptiveness of the results. Analysis of the experimental data shows that the propagation velocities of bulk and rod elastic waves in different ways reflect the compaction and contact formation in powder materials. The differences are explained by the peculiarities of acoustic fields generated by various types of elastic waves.

Interaction between bubble and particle in spherical liquid cavity surround by an elastic medium

A theory is developed to model the dynamic of bubble and particle inside a spherical liquid-filled cavity surrounded by an elastic medium. The aim of this work is to study how the outer elastic medium affects the interaction between bubble and particle. Starting from the theory of velocity potential distribution, combined with Lagrangian equations, the motion equations of bubbles and particles in the cavity are obtained. The resonance frequency of the bubbles and influence of the interaction between particle and bubble on the translational behavior under the action of sound waves are analyzed. The results show that the properties of medium elasticity and density can change the resonance frequency of the bubble in the cavity. As the radius of the spherical cavity increases, the resonance frequency of the bubble has a tendency to first decrease and then increase, and gradually tends to the resonance frequency of a single bubble in an unbounded liquid. The translation of bubble and particle in the spherical liquid cavity is affected by factors such as acoustic field parameters, the characteristics of the outer elastic medium, and the characteristics of the bubble and particle themselves. The overall characteristic is that the particle has a tendency to move to the cavity wall, and the translation of bubble is closely related to the interaction characteristics between bubble and particle.

DETERMINATION OF THE NOISE POWER GENERATED BY THE POWDER SUPERSONIC JETS (SSJ)

The paper analyzes the results of experimental studies of the parameters of acoustic fields generated by the jets of small-scale solid fuel rocket engines (SFRE). The field of isobars of sound pressure created by a supersonic jet (SSJ) is considered. To identify the most correct approach to determining the acoustic power of the SSJ, a numerical integration of the power of pressure pulsations along the length of the jet was performed.

Restoration of acoustic field parameters measured by a fiber multi-sensor system on a turbomachine nozzle slice

The article is devoted to the development and research of distributed fiber systems for aeroacoustic control of gas-air flow parameters on the nozzle section of turbomachines. The problem of source localization and restoration of the acoustic field of turbomachines is considered. The control of the aeroacoustic control system based on fiber-optic sensors based on the principles of self-learning is considered, since extreme controllers, although simply technically implemented, but have low speed, which is especially affected with a large number of control elements. Therefore, the aeroacoustic fiber-optic complex will be considered in the form of an automatic control system with the adaptation of the parameters of the mathematical model by the measured values of the flow parameters that change with the change of the

Portable stand used to visualize acoustic fields surrounding machines

Visualization of the parameters of acoustic field is a relatively new research technique that allows for illustrate the parameters characterizing the acoustic field for specific points of space near the machine. Images obtained in this way have many applications in the analysis of prototype devices, construction, as well as in the analysis of the acoustic field around industrial machines. The article presents the principles of operation of the mobile experimental setup. The results of studies of noise emission on the example of loudspeaker set and vacuum pump are also discussed.

Modeling Magnetic, Electric, and Acoustic Fields of a Pass-Through Transducer When Testing Cylindrical Objects

We present results of numerically modeling the magnetic, electric, and acoustic fields of a pass-through EMA transducer of longitudinal waves by the finite element method in the COMSOL Multiphysics software environment. The main approaches used in the modeling are described. The influence of structural gaps between the EMA transducer and the test object on the magnitude and distribution of eddy current density, as well as the main and interfering components of a bias field have been investigated. The influence of operating frequency on acoustic field parameters has been analyzed. Recommendations are given on the choice of transducer’s operating frequency and probing-pulse quality factor needed to shape the required diagram of displacements relative to the object diameter and to assess the sensitivity to surface and internal defects located at different depths.

Development of a freely available simulator with graphical interface for modeling nonlinear focused ultrasound fields with shocks

Measurement-based modeling is gaining acceptance as a standard tool for characterizing the nonlinear fields of existing therapeutic ultrasound devices and designing new ones. Here, a freely available simulation tool is presented for modeling axially symmetric, strongly nonlinear HIFU beams with shocks in a layered propagation medium such as water and different types of tissue. Two nonlinear wave equations are included in the simulator: the KZK equation generalized to include an equivalent source boundary condition for strongly focused beams and the Westervelt equation in a nonlinear wide-angle parabolic representation. Both equations are solved in the frequency domain and permit definition of the HIFU transducer as an annular array. The geometrical parameters and power output of the array, electronic focus steering along the beam axis, and acoustic properties of the layered propagation medium can be configured via graphical interface. Visualization and output of various acoustic field parameters such as peak positive and negative pressures, shock amplitude, intensity, heat deposition rate, and total power of a beam are also provided. The simulator can be used for transducers without ideal symmetry through definition of an equivalent radially symmetric source. Widespread availability of such simulation tools will help advance standardized utilization of measurement-based modeling and facilitate the adoption of such approaches for HIFU treatment planning. [Work supported by NIH R01EB7643, R01EB025187, and RSF №14-12-00974.]

Activation of Piezo1 but Not NaV1.2 Channels by Ultrasound at 43 MHz

Ultrasound (US) can modulate the electrical activity of the excitable tissues, but the mechanisms underlying this effect are not understood at the molecular level or in terms of the physical modality through which US exerts its effects. Here, we report an experimental system that allows for stable patch-clamp recording in the presence of US at 43 MHz, a frequency known to stimulate neural activity. We describe the effects of US on two ion channels proposed to be involved in the response of excitable cells to US: the mechanosensitive Piezo1 channel and the voltage-gated sodium channel NaV1.2. Our patch-clamp recordings, together with finite-element simulations of acoustic field parameters indicate that Piezo1 channels are activated by continuous wave US at 43 MHz and 50 or 90 W/cm2 through cell membrane stress caused by acoustic streaming. NaV1.2 channels were not affected through this mechanism at these intensities, but their kinetics could be accelerated by US-induced heating.

Sound speed and attenuation in marine mud seabottom

Acoustic propagation in shallow water is greatly influenced by the properties of the bottom. Comparing the acoustic characteristics in the sediments of sand or silty are well inverted or directly core measured, sound speed and attenuation in the mud sediment still need investigated further. An experiment was performed in the Yellow Sea in 2002 to inversion for the acoustic parameters. In the experiment, six different sediment types: Fine Sand, Silty Sand, Sand Silty, Sand-Silty-Clay, Silty Clay and Mud, are included in an area. A hybrid geoacoustic inversion scheme, which combines several inversion methods together to invert for the bottom parameters, is proposed based on the fact that the bottom acoustic parameters have different sensitivities to the different physical parameters of acoustic field. The inverted bottom parameters could distinguish the atlas marked bottom type quite well. The sound speed and attenuation parameter in the marine sediments of silty clay and mud is mainly discussed. The nonlinear frequency relationship of attenuation in the mud is compared with that of silty sand. [Work supported by the National Natural Science Foundation of China under Grant No. 11434012 and Grant No. 41561144006.]

On the influence of stochastic pulsations of a bubble on its translational motion

This communication is devoted to theoretical analysis of the dynamics of a solitary cavitation bubble pulsating in a compressible viscous liquid under the action of a nonuniform acoustic field. The system of two nonlinear ordinary second-order differential equations is integrated numerically. In the range of acoustic field parameters corresponding to the principal resonance region, the bubble performs large-scale spatial oscillations. It is shown that in a very small range of initial radii, the bubble stops its oscillatory motion due to stochastic pulsations and is expelled into the region of the acoustic-pressure block. Therefore, stochastic pulsations of the bubble radically change the form of the solution to the system of the above-mentioned equations.

Effect of acoustic field parameters on arc acoustic binding during ultrasonic wave-assisted arc welding

As a newly developed arc welding method, power ultrasound has been successfully introduced into arc and weld pool during ultrasonic wave-assisted arc welding process. The advanced process for molten metals can be realized by utilizing additional ultrasonic field. Under the action of the acoustic wave, the plasma arc as weld heat source is regulated and its characteristics make an obvious change. Compared with the conventional arc, the ultrasonic wave-assisted arc plasma is bound significantly and becomes brighter. To reveal the dependence of the acoustic binding force on acoustic field parameters, a two-dimensional acoustic field model for ultrasonic wave-assisted arc welding device is established. The influences of the radiator height, the central pore radius, the radiator radius, and curvature radius or depth of concave radiator surface are discussed using the boundary element method. Then the authors analyze the resonant mode by this relationship curve between acoustic radiation power and radiator height. Furthermore, the best acoustic binding ability is obtained by optimizing the geometric parameters of acoustic radiator. In addition, three concave radiator surfaces including spherical cap surface, paraboloid of revolution, and rotating single curved surface are investigated systematically. Finally, both the calculation and experiment suggest that, to obtain the best acoustic binding ability, the ultrasonic wave-assisted arc welding setup should be operated under the first resonant mode using a radiator with a spherical cap surface, a small central pore, a large section radius and an appropriate curvature radius.