共查询到20条相似文献,搜索用时 15 毫秒
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空泡广泛存在于自然界中,理论和实验表明,空泡在坍塌时可以将能量密度提高-10^12倍,发出皮秒级超短脉冲闪光,文章对液体介质中的空泡规律和常用研究方法进行了描述,主要内容包括空泡动力学、声致发光、冲击波产生、激光空泡及空泡应用前景介绍。 相似文献
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对单泡声致发光过程采用等离子体描述,考虑了各种等离子体输运过程,假设了声致发光的轫致辐射机制,数值模拟的结果与实验很好地吻合,有力地支持了声致发光的热转向的解释,预言了声致发光中可能出现的极端电现象,对各物理量时空剖面的分析表明,强电场的出现中能产生的Rayleigh-Taylor不稳定性有制约作用,这可能是声致发光约10^12能量汇集的原因之一。 相似文献
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The numerical results obtained by Rayleigh-Plesset (R-P) equation failed to agree with the experimental Mie scattering data of a bubble in water without inappropriately increasing the shear viscosity and decreasing the surface tension coefficient. In this paper, a new equation proposed by the present authors (Qian and Xiao) is solved. Numerical solutions obtained by using the symbolic computation program from both the R-P equation and the Qian-Xiao (Q-X) equation clearly demonstrate that Q-X equation yields best results matching the experimental data (in expansion phase). The numerical solutions of R-P equation also demonstrate the oscillation of a bubble in water depends strongly upon the surface tension and the shear viscosity coefficients as well as the amplitude of driving pressure, so that the uniqueness of the numerical solutions may be suspected if they are varied arbitrarily in order to fit the experimental data. If the bubble's vibration accompanies an energy loss such as the light radiation during the contract phase, the mechanism of the energy loss has to be taken into account. We suggest that by use of the bubble's vibration to investigate the state equations of aqueous solutions seem to be possible. We also believe that if one uses this equation instead of R-P equation to deal with the relevant problems such as the 'phase diagrams for sonoluminescing bubbles', etc., some different results may be expected. 相似文献
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Production of large size single transient cavitation bubbles with tube arrest method 总被引:3,自引:0,他引:3 下载免费PDF全文
Large size single transient cavitation bubbles of maximum diameter up to 3 cm with sonoluminescence have been generated in water by the ‘tube arrest' method. A simplified one-dimensional model of bubble growing and water column motion is proposed. The results of numerical simulation are compared with the experimental data of the bubble size and oscillation period as the key parameters. 相似文献
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Based on the introduction of international progress, our investigations on acoustic cavitation have been reported. Firstly
we considered the cavity’s dynamics under the drive of the asymmetrical acoustic pressure. An aspheric dynamical model was
proposed and a new stable and aspheric solution was found in numerical simulation of the theoretical framework of the aspheric
model. Then, a dual Mie-scattering technique was developed to measure the cavity’s aspheric pulsation. A significant asynchronous
pulsation signal between two Mie-scattering channels was caught in the case of large cavity driven by low acoustic pressure.
As a direct deduction, we observed an evidence of cavity’s aspheric pulsation. Furthermore, we studied the dependency of the
asynchronous pulsation signal on the various parameters, such as the amplitude and frequency of the driving acoustic pressure,
and the surface tension, viscosity and gas concentration of the liquid. Finally, we introduced a new numeric imaging technique
to measure the shapes of the periodic pulsation cavities. The time-resolution was in the order of 20 ns, one order of magnitude
lower than that in the previous work, say, 200 ns. 相似文献
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首先阐述了换路后电容电压或电感电流发生突变的充要条件,然后得出有关冲激强度的两个结论,最后介绍了如何应用冲激强度去确定电路换路后的初始状态。 相似文献
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简要概述了20世纪20年代起多泡声空化的发现、研究和应用,随后重点介绍了20世纪90年代初实现的稳态单一气泡;由于它的实现,对声空化的实验研究和理论研究迅速取得进展,特别是在对气泡内部的极端条件(高温、高压、高密度)以及对气泡内声致发光的机理研究方面,同时还介绍了我国早在20世纪60年代实现的瞬态单一泡以及近期的一些实验结果。文章最后提到2002年3月美国报道的声空化核辐射实验,这个实验正在激发人们对声空化的更多关注。 相似文献
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非线性声波方程与气泡脉动方程联立, 可以描述声空化云中的声场以及任何一个气泡的脉动过程,为数值计算空化场问题提供了理论框架.计算的声压分布变化可以用来计算单气泡动力学,了解任何位置处气泡发光过程以及气泡内气体温度和压强变化等. 对浓硫酸中氙气泡空化云的计算定性符合实验观测, 只有钠原子线谱的计算结果相比实验观测有些出入. 相似文献
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香蕉叶片Chla荧光动力学参量对激发光强的反应 总被引:5,自引:4,他引:1
在蓝色激发光(λm=660nm)作用下,香蕉叶片的叶绿素a(Chla)发出波长为720~740nm的荧光信号,荧光强度随时间呈现有规律的变化.随着激发光强的增加,荧光动力学参量F0和FVI/FV呈上升趋势,FV/F0与FV/FM逐渐达到饱和,而CA和T1/2呈下降趋势.研究结果表明,保证香蕉叶片光合机构高速有序运转的适宜光强在20~60μmol·m-2·s-1之间,过量的光强将造成叶片光合机构的损伤.讨论了香蕉叶片诸荧光动力学参量的生物学意义及其随激发光强度增加而变化的原因. 相似文献
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在5—25keV单能刻度用X射线发生器上,用充氩密封式正比计数管直接测量了X射线量子效率为0.877±0.011—0.107±0.002,推算出X射线发生器绝对产额为(1.40±0.03)×10~(10)—(9.20±0.39)×10~8/s。 相似文献
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此文用代数张量法导出甲烷分子两个基频谱带的转动跃迁矩阵元,对这两个谱带的谱线强度进行了计算和比较,给出满意的结果。 相似文献
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