共查询到19条相似文献,搜索用时 328 毫秒
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1引言
声致发光是一种将声能转化为光能的复杂的物理化学过程.大量在空间和时间都随机、不稳定的声致发光是多泡声致发光.而空间上固定,时间上具有周期性的是单泡声致发光.一直以来,只在多泡声致发光中发现了明显的谱线,所以认为多泡声致发光和单泡声致发光出于不同的机制.但是D.J.Flannigan和K.S.Suslick[1]以85%的浓硫酸为单泡声致发光的工作液体,观测到了明显的Ar原子谱线.根据原子发光理论可以很好地解释Ar原子谱线.本文试图对不同温度下Ne,Kr,Xe原子气泡的单泡声致发光特征谱线进行了理论计算,期待实验的验证. 相似文献
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0引言Gaitan等人在1992年首次实现了单个气泡的声致发光,即单泡声致发光[1](Single bubble sonoluminescence,缩写为SBSL)。而之前的气泡群声致发光现象称为多泡声致发光[2](Multi-bubble sonoluminescence,缩写为MBSL)。光谱测量一直是研究声致发光的有效手段之一。1995年,Matula等人[3]根据MBSL和SBSL的光谱,分析认为两者的区别是SBSL只有连续谱,而MBSL除了有连续 相似文献
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1.引言
在超声驻波的作用下,在除气水中可以实现单个气泡的超声悬浮,同时气泡也将会以驱动频率做膨胀塌缩运动,塌缩的剧烈程度随着声压的增加而变剧烈,当声压大到一定值时,在气泡的塌缩过程中就会发出光脉冲,这就是单泡声致发光(SBSL).既然SBSL是由于气泡的运动所产生的,那么研究气泡具体是如何运动的就变得十分重要,这将有助于了解声致发光的发光机理和过程.当然,影响声致发光的因素有很多,如声压、含气量、环境温度和压力、以及一些液体参数等等,其中激励声压是最根本的一个相关量.本文我们研究激励声压对气泡运动的影响. 相似文献
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简单地介绍了声致发光现象以及研究这一现象的意义。在此基础上详细地介绍了液体中实现声致发光的实验装置及其工作原理,以及声致发光光强测量装置。较为详细地叙述了信号发生器、功率放大器、可调电感、谐振腔(压电换能器)、磁力搅拌器、数字电压表、光电倍增管及数字示波器等部件在实验中的功能和作用、具体操作方法和实验步骤。根据测量得到的实验数据总结了影响声致发光现象的主要因素,即实验环境温度、驱动声压信号频率及驱动声压大小等等。对实验过程中遇到的一些问题给出解决方案,并提出了改善实验仪器的建议。 相似文献
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Gustavo C. Buscaglia Ionel Ciuperca Eric Dalissier Mohammed Jai 《Journal of Engineering Mathematics》2013,83(1):57-79
A generalization of the Elrod–Adams model of cavitation in lubricated devices is proposed, such that the translation velocity $V$ for the saturation field $\theta $ can be given any value between $S/2$ and $S$ , with $S$ being the relative speed of the surfaces. The lack of uniqueness of the classical model when $V\ne S/2$ is explained and a suitable supplementary condition is proposed to fix this issue. The new model is rigorously analyzed, though in the simplified mathematical setting of a one-dimensional problem with a single pressurized region. The main result states the existence of a unique solution globally in time, unless of course the cavitation boundary leaves the domain or disappears. A few preliminary numerical examples are included to illustrate the model. 相似文献
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Vijay H. Arakeri 《Sadhana》1981,4(3):381-393
The possible role of reaj fluid effects in two aspects of flow cavitation namely inception and separation is discussed. This
is primarily qualitative in the case of inception whereas some quantitative results are presented in the case of separation.
Existing evidence clearly indicates that in particular viscous effects can play a significant role in determining the conditions
for cavitation inception and in determining the location of cavitation separation from smooth bodies. 相似文献
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Cavitation phenomenon is studied in rubber-like materials by combining experimental, theoretical and numerical approaches. Specific tests are carried out on a Styrene Butadiene Rubber to point out main characteristics of cavitation phenomenon. Hydrostatic depression is numerically modelled using finite element method. Numerical results are compared to Ball’s and Hou & Abeyaratne’s models with regard to cavity nucleation in the material. Both models well fit experimental observations suggesting that the cavitation nucleation in elastomers depends on the confinement degree of the specimen. Finally, critical hydrostatic pressure and critical global deformation are proved to govern cavitation nucleation in the studied material. Critical loadings are identified by comparing experimental and numerical load–displacement curves. 相似文献
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Hybridization enhancement using cavitation microstreaming 总被引:2,自引:0,他引:2
Conventional DNA microarray hybridization relies on diffusion of target to surface-bound probes, and thus is a rate-limited process. In this paper, a micromixing technique based on cavitation microstreaming principle that was developed to accelerate hybridization process is explained. Fluidic experiments showed that air bubbles resting on a solid surface and set into vibration by a sound field generated steady circulatory flows, resulting in global convection flows and, thus, rapid mixing. The time to fully mix dyed solutions in a 50-microL chamber using cavitation microstreaming was significantly reduced from hours (a pure diffusion-based mixing) to 6 s. Cavitation microstreaming was implemented to enhance DNA hybridization in both fluorescence-detection-based and electrochemical-detection-based DNA microarray chips. The former showed that cavitation microstreaming results in up to 5-fold hybridization signal enhancement with significantly improved signal uniformity, as compared to the results obtained in conventional diffusion-based biochips for a given time (2 h). Hybridization kinetics study in the electrochemical detection-based chips showed that acoustic microstreaming results in up to 5-fold kinetics acceleration. Acoustic microstreaming has many advantages over most existing techniques used for hybridization enhancement, including a simple apparatus, ease of implementation, low power consumption (approximately 2 mW), and low cost. 相似文献
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C. Cheng A. Hiltner E. Baer P. R. Soskey S. G. Mylonakis 《Journal of Materials Science》1995,30(3):587-595
Particle cavitation in the stress-whitened zone ahead of a semicircular notch in polycarbonate blended with a core-shell rubber was characterized by transmission electron microscopy. Cavitation of rubber particles at five locations in the stress-whitened zone was correlated with the local stress and strain history. It was found that cavitation initiated some distance ahead of the notch when a mean stress condition was met. Initially, only a fraction of the particles cavitated and these were randomly distributed. Single cavitated particles grew into cavitated domains by cooperative cavitation of nearby particles until cavitation was arrested when shear yielding of the matrix provided an alternative mechanism for relief of strain energy. Far from the notch, where the stress state approached uniaxial tension, cavitated domains grew into linear arrays of cavitated particles. A mechanism of cooperative crazing in microlayer composites of polycarbonate and styrene/acrylonitrile copolymer was adapted to cooperative cavitation of core-shell rubber particles. It was proposed that cooperative cavitation of nearby particles occurred by impingement of a small plastic zone that formed at the equator of a cavitated particle. 相似文献
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Shchukin DG Skorb E Belova V Möhwald H 《Advanced materials (Deerfield Beach, Fla.)》2011,23(17):1922-1934
In spite of the great potential of applying high-intensity ultrasound, which enables high-temperature and high-pressure chemistry with a reactor near room temperature and ambient pressure, sonochemistry at solid surfaces is at a weak stage of understanding with regards to the development of new materials and composite nanostructures. The science towards a quantitative understanding is only now emerging. On the other hand, in many applications an ultrasonic bath is used without thinking of the mechanism. Often surfaces are exposed to ultrasound for cleaning. Since ultrasonic treatment is not an exotic process and applicable even on large scale in industrial manufacturing, controlling the process may lead to new applications making use of the specially designed surface. This review is intended to summarize recent progress in this field and to point out most promising directions of ultrasound application for the development of new materials with functional surfaces. 相似文献
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A boundary element method is applied to predict the unsteady cavitating performance of marine propellers subject to a non-axisymmetric
inflow with the complete tunnel wall effect. The tunnel and propeller problem is solved directly to predict the fully unsteady
performance of the cavitating propeller. The cavitation on blade and wake surface is determined by applying the dynamic and
the kinematic boundary conditions on the cavity surface. The potential on the cavity surface is known from the dynamic boundary
condition and the relation between cavitation number and cavity velocity. Once the boundary value problem is solved for the
unknowns- the potentials on the wetted blade surface and the normal derivative of potentials on the cavity surface – the new
cavity shape is adjusted by using the normal derivative of the potential. The potential on the new cavity surface is determined
by using the kinematic boundary condition on the cavity. The procedure is repeated until the cavity shape converges and the
pressure on the cavity becomes constant. To validate the present method, the effects of the number of blade panels and the
dimensions of the tunnel walls on blade forces are presented. The predicted cavity patterns are compared with those observed
from experiment. 相似文献