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A new design idea for a monopole acoustic transducer which increases the frequency band and improves electromechanical performance is proposed with a focus on the lowest order of the radial and flexural modes. Numerical modeling of the resonance frequencies and electrical conductance are conducted with respect to the dimensions and material parameters of the proposed transducer. The transmitting voltage response level with respect to the density and velocity of the fluid media is calculated. The numerical simulation is validated through experiments. The frequency band and the electromechanical performance of the monopole acoustic transducer can be optimized by the g~ven methods concluded from the numerical results. 相似文献
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Acoustical Physics - The article studies the spectrum of acoustic oscillations generated by interdigital transducers in a plate made from a LiNbO3 piezocrystal with a thickness on the order of the... 相似文献
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The theory of nonresonant Brillouin scattering in anisotropic piezoelectric semiconductors with deformation potential coupling and piezoelectric coupling between excited systems of acoustic phonons and conduction electrons is reviewed. The scattering efficiency is calculated using the appropriate dyadic electromagnetic GreeN′s function. The depletion of the scattered intensity arising from a non phase-matched scattering kinematics and from a spatial exponential decay of the sound amplitude is taken into account. The contributions to the Brillouin scattering from the free-carrier-screened indirect photoelastic effect and from the free-carrier density modulation are expressed in terms of the self-consistent electric field. This field is obtained from a Boltzmann-equation calculation of the effective ac conductivity tensor. The acoustic dispersion of the Brillouin-scattering efficiency is considered, and some possibilities of determining electronic transport properties by means of Brillouin scattering are outlined. 相似文献
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Acoustical Physics - Sound propagation in a piezoelectric medium with a periodic lattice in the presence of charge carrier drift is considered. A periodic lattice creates a scattered component with... 相似文献
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Acoustical Physics - The focusing principle and acoustic field characteristics of curved array probe are studied. Delay laws are first computed in the same way as linear array probe, and its... 相似文献
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无论是乐器还是喉咙发出的音乐声,总要经过传播才能被人听到.声波在空气中传播当然以直线传播为主,但反射和衍射不可避免的存在,而且对音乐的效果有重要影响.音乐在旷野、山颠、院落或室内,听起来强度和音色各不相同,无论是听者还是演唱者,感受都大不一样,可见环境对乐音的响度或音色是有影响的,这里的区别主要是反射的效果. 相似文献
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HAO Luyuan REN Zhi SHI Qiang ZHENG Yan ZHENG Jingjing ZHU Qingshi 《Chinese Journal of Lasers》2001,10(2):107-113
1 Introduction Thephotoacoustictechnique ,basedonthedirectmeasurementoftheheatgeneratedinnonradiativerelaxation processes ,isamethodofabsolutemeasurement.Inthecaseofweakabsorption ,photoacousticsignalsareproportionaltothelightabsorbedbysamplesandhenceto… 相似文献
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The sandwich transducer structure is comprised of three components along its main axis: the back metal cap, piezoelectric ceramic stack and the horn. The purpose of this work is to present a simplified method, referred as the equivalent length algorithm, to design the actuator parameters including each segment length and the resonance frequency fs. The actuator length L and the propagation wavelength λ along its main axis satisfy the standing wave theory. So, define an equivalent length coefficient for each part of the actuator, and then the sandwich structure is regarded as a single material cylindrical rod with equivalent length L′. According to the standing wave theory, the equivalent length L′ of the actuator can be determined with the given resonance frequency fs, or vice versa. The phase length of each part of the actuator in the standing wave is optimized freely in the design procedure. The actual length of each part of the actuator is determined by the equivalent length coefficient. Finally, the resonance frequencies of three given actuators are calculated with this method. They are compared with those obtained through Ansys simulation and those measured by an impedance analyzer. The results show agreement. 相似文献
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The size of a cylindrical photoacoustic cell with suitable size was selected so that the resonant frequency of the first radial mode was equal to that of a longitudinal higher mode. By maintaining two thin coaxial tubes at each end, a enhanced photoacoustic cell was constructed with two tubes of 1/2 and 1/4 of the wavelength. In this enhanced photoacoustie cell, both the first radial resonance and the higher longitudinal resonance were excited adequately. Coupling of two acoustic modes makes the acoustic energy concentrating in the middle of the cell. The surface loss was decreased, the acoustic quality factor and pressure amplitude increased obviously as compared with conventional cylindrical cell. 相似文献
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Acoustic fluxes constituting an acoustic domain in a piezoelectric semiconducting n-CdS were analyzed by Brillouin scattering method. Obtained results were as follows: 0.8 GHz and 2.0 GHz acoustic fluxes were faster than the sound velocity 1.75 × 105 cm/s. The observed profile of the 2.0 GHz flux agreed fairly well with the simulated one performed numerically by KdV equation. The faster positions of the acoustic domain were formed by lower frequency acoustic fluxes and the slower positions understood by acoustic fluxes around maximum gain frequency generated first in a small signal regime. 相似文献
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Calculation of Surface Acoustic Waves in Crystals Using the Global Optimization Procedure 总被引:2,自引:0,他引:2
Dvoesherstov M. Yu. Cherednik V. I. Chirimanov A. P. 《Radiophysics and Quantum Electronics》2000,43(9):719-729
The characteristics of surface acoustic waves are calculated using the procedure of searching for the global extremum of a multivariable function. This procedure is used to minimize the determinant of the boundary conditions to seek orientations in piezocrystals that are optimal from the viewpoint of acoustic-wave characteristics and to find pseudosurface (leaky) acoustic waves existing only in the vicinity of specific orientations. 相似文献
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核磁共振(NMR)测井仪以CPMG脉冲序列为测量基础,按照CPMG脉冲序列的时序要求完成大功率射频脉冲的发射和微弱回波信号的接收, 在脉冲发射完成后快速泄放天线中储存的能量. 该文介绍一种基于现场可编程门阵列(FPGA)的NMR测井仪控制逻辑和典型脉冲序列,详细说明在CPMG脉冲序列下FPGA的工作时序和流程;讨论NMR测井仪发射电路、Q-转换电路和隔离电路的控制原理和时序要求,给出各电路的控制逻辑仿真结果;最后,利用所设计的控制逻辑和自制NMR测井仪探头,在实验室条件下对水溶液进行了测量,得到满意的结果. 相似文献
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Acoustical Physics - The authors have carried out an experimental and theoretical study of the propagation of surface acoustic waves (SAW)—Rayleigh, Sezawa and SH-modes, as well as Lamb waves... 相似文献
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Wael A. Altabey 《声与振动》2020,54(4):215-224
The optimization of the acoustic silencer volume is very important to develop it and to get high-performance, the importance of the silencer was appeared in industrial field to eliminate the noise of the duct by efficient and economical method. The main goal of this research is to optimize the transmission loss (TL) by analytical method of the Double-Chamber Silencer (DCS), the TL has been selected as the main parameter in silencer because it does not based on the source or the termination impedances. First we calculated the power transmission coefficient (PTC) and the TL of an acoustic silencer, then used the Lagrange method to optimize the silencer length. All calculation of silencer data is obtained by solving the governing equations in commercial software Matlab®. A several calculations for different silencer length at many frequency ranges were performed simultaneously. Finally, this research supports the efficient and rapid techniques for DCS optimal design under narrow space. The results show that the acoustic TL is maximized at the desired frequency. 相似文献
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Acoustical Physics - Acoustic metamaterials have become a novel and effective way to control sound waves and design acoustic devices. In this study, we design a 3D acoustic metamaterial lens (AML)... 相似文献
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We present a design of an acoustic levitator consisting of three pairs of opposite transducer arrays.Three orthogonal standing waves create a large number of acoustic traps at which the particles are levitated in mid-air.By changing the phase difference of transducer arrays,three-dimensional manipulation of particles is successfully realized.Moreover,the relationship between the translation of particles and the phase difference is experimentally investigated,and the result is in agreement with the theoretical calculation.This design can expand the application of acoustic levitation in many fields,such as biomedicine,ultrasonic motor and new materials processing. 相似文献