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We experimentally investigate the single-bubble sonoluminescence(SBSL)under different driving pressures.The spectrum of SBSL,pulse shape of light emission and the SBSL phase that is compared with a sinusoidal driving pressure are all studied.The results show that the temperature and the width of the light pulse increase with increasing sound pressure.So does the phase of SBSL emission,which agrees very well with the numerical calculation result.At the same time,a possible method of determining the value of sound pressure was discussed. 相似文献
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Hyperthermia effects (39-44°C) induced by pulsed high-intensity focused ultrasound (HIFU) have been regarded as a promising therapeutic tool for boosting immune responses or enhancing drug delivery into a solid tumor. However, previous studies also reported that the cell death occurs when cells are maintained at 43°C for more than 20 minutes. The aim of this study is to investigate thermal responses inside in vivo rabbit auricular veins exposed to pulsed HIFU (1.17 MHz, 5300 W/cm2 , with relatively low-duty ratios (0.2%-4.3%). The results show that: (1) with constant pulse repetition frequency (PRF) (e.g., 1 Hz), the thermal responses inside the vessel will increase with the increasing duty ratio; (2) a temperature elevation to 43°C can be identified at the duty ratio of 4.3%; (3) with constant duty ratios, the change of PRF will not significantly affect the temperature measurement in the vessel; (4) as the duty ratios lower than 4.3%, the presence of microbubbles will not significantly enhance the thermal responses in the vessel, but will facilitate HIFU-induced inertial cavitation events. 相似文献
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A dynamical propagation model coupled to the oscillation of cavitation bubbles is applied to describe the imploding acoustic field in a cavitating liquid where the acoustic waves transmit from the outside to the inside of a circle disk. Numerical simulation shows that the imploding ability of a ring source can elevate the sound pressure or partly eliminate the decay due to both the bulk attenuation and the attenuation caused by cavitation. However,the imploding ability is limited and there exists a critical radius. When the radius of the disk is larger than the critical one, the imploding ability is not enough to eliminate the attenuation. Fortunately, the cavitation region can be effectively expanded if a hot plate is attached under the center of the disk because the cavitation threshold is related to the temperature of the liquid, which means that a region with good uniformity of cavitation can be enhanced by adjusting the temperature difference between the central and side liquid. 相似文献
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正2016年9月4日是我国声学泰斗魏荣爵先生诞辰一百周年,《声学学报》特发专辑以纪念和表彰魏荣爵先生为发展我国声学教育和科研事业所作出的杰出贡献,这表达了我们广大声学工作者共同的心声。作为魏先生的学生,积极响应为专刊撰写论文,介绍先生生前感兴趣领域最近所取得的进展和动态,告慰先生在 相似文献
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研究了非线性传输线电路禁带内能量的不对称传输现象. 传输线电路中的两子电路结构相同,电感参数不同,并且具有低通滤波器的特点. 鉴于驱动频率在通频带的截止频率之上,所以形成不对称能流的载体为 禁带内传播的非线性波.该研究中,产生不对称能量传输的机理与非线性超传导现象密切相关. 通过调整耦合电感的大小,总结出传输能量与耦合强度之间的变化规律. 同时也采用仿真的方式分析了驱动电压幅值与传输能量间的相关性. 最后,通过在实验上改变驱动频率的大小,得到超传导发生时的门限电压与驱动频率间的依赖关系, 该关系与理论计算的结果完全定性一致. 相似文献
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报道在垂直激励下颗粒物质的表面孤立于波形隆起及内部的对流分布的实验观察.通过分析,得到一种不同干以往依赖于水平方向边界制约的但却类似于浅水表面波的新的形成机制.
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Computational simulation of ionization processes in single-bubble and multi-bubble sonoluminescence
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Jin-Fu Liang 《中国物理 B》2022,31(11):117802-117802
The most recent spectroscopic studies of moving-single bubble sonoluminescence (MSBSL) and multi-bubble sonoluminescence (MBSL) have revealed that hydrated electrons (e$_{{\rm aq}}^{-}$) are generated in MSBSL but absent in MBSL. To explore the mechanism of this phenomenon, we numerically simulate the ionization processes in single- and multi-bubble sonoluminescence in aqueous solution of terbium chloride (TbCl$_{3}$). The results show that the maximum degree of ionization of single-bubble sonoluminescence (SBSL) is approximately 10000 times greater than that of MBSL under certain special physical parameters. The hydrated electrons (e$_{{{\rm aq}}}^{-}$) formed in SBSL are far more than those in MBSL provided these electrons are ejected from a bubble into a liquid. Therefore, the quenching of e$_{{{\rm aq}}}^{-}$ to SBSL spectrum is stronger than that of the MBSL spectrum. This may be the reason that the trivalent terbium [Tb(III)] ion line intensities from SBSL in the TbCl$_{3}$ aqueous solutions with the acceptor of e$_{{{\rm aq}}}^{-}$ are stronger than those of TbCl$_{3}$ aqueous solutions without the acceptor of e$_{{{\rm aq}}}^{-}$. Whereas the Tb(III) ion line intensities from MBSL are not variational, which is significant for exploring the mechanism behind the cavitation and sonoluminescence. 相似文献
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A reverse-conducting lateral insulated-gate bipolar transistor(RC-LIGBT) with a trench oxide layer(TOL), featuring a vertical N-buffer and P-collector is proposed. Firstly, the TOL enhances both of the surface and bulk electric fields of the N-drift region, thus the breakdown voltage(BV) is improved. Secondly, the vertical N-buffer layer increases the voltage drop VPNof the P-collector/N-buffer junction, thus the snapback is suppressed. Thirdly, the P-body and the vertical N-buffer act as the anode and the cathode, respectively, to conduct the reverse current, thus the inner diode is integrated. As shown by the simulation results, the proposed RC-LIGBT exhibits trapezoidal electric field distribution with BV of 342.4 V, which is increased by nearly 340% compared to the conventional RC-LIGBT with triangular electric fields of 100.2 V. Moreover,the snapback is eliminated by the vertical N-buffer layer design, thus the reliability of the device is improved. 相似文献