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Acoustic Nonlinear Behaviour of Microbubble Contrast Agent   总被引:2,自引:0,他引:2       下载免费PDF全文
俞金飞  石涛 《中国物理快报》2002,19(12):1828-1830
We have investigated the nonlinear characteristics of a microbubble contrast agent Sonazoid (Nycomed,Norway),including the second,thire,1/2-order,3/2-order and 5/2-order harmonics,We have measured the 1/2-order subharmonic response to different transmission sound pressures.We have found that subharmonic signals connot be generated until the acoustic pressure reaches a certain value,which is the most different subharmonic from high harmonics,This results is favourable for the further study of the subharmonic in the bubble liquid.The 3/2-order ultraharmonic response to acoustic pressure was also measured.  相似文献
2.
We propose a time-domain theoretical approach to predict the acoustic nonlinear field radiated from a concave focusing spherical source with a wide aperture angle. The nonlinear sound propagation is theoretically described by an accurate mathematical model including the continuity and momentum equations. Numerical calculation is implemented by using the finite difference time domain algorithm in the oblate spheroidal coordinate system. To examine the validity of the theoretical model, we calculate the sound fields radiated from concave spherical focusing transducers with aperture angles 30° and 40° and the results are compared with those obtained by the SBE solution.  相似文献
3.
Periodic arrays of resonant shunted piezoelectric patches are employed to control the wave propagation in a two-dimensional (2D) acoustic metamaterial. The performance is characterized by the finite element method. More importantly, we propose an approach to solving the conventional issue of the nonlinear eigenvalue problem, and give a convenient solution to the dispersion properties of 2D metamaterials with periodic arrays of resonant shunts in this article. Based on this modeling method, the dispersion relations of a 2D metamaterial with periodic arrays of resonant shunted piezos are calculated. The results show that the internal resonances of the shunting system split the dispersion curves, thereby forming a locally resonant band gap. However, unlike the conventional locally resonant gap, the vibrations in this locally resonant gap are unable to be completely localized in oscillators consisting of shunting inductors and piezo-patches.  相似文献
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