倾斜方管内气液两相分层流界面的稳定性分析

利用双流体模型推导了倾斜方管内气液两相流界面波的色散方程，分析了界面的稳定性，系统研究了管道尺寸，气液两相流量，液相粘度，表面张力及通道倾角对界面稳定性的影响。     

二维数值造波水槽不规则波之数值研究

利用边界元素法所建立数值造波水槽探讨不规则波浪之造波与传递问题，以Lagrange法描述水粒子之运动并利用前进差分处理时间项之微分项。水槽一端为活塞推拉式造波板，运动方式以Mitsuyasu-Bretschneider之波谱造波，另一侧设有一段消波区以减少计算结果受波浪反射之影响。水面上选定若干个测点量取水位变化之历时，利用波谱分析水面上各测点之波谱并与原入射波波谱比较来探讨本模式之准确性。     

多模态超声导波管道检测技术的研究

目前管道检测技术尚难实现大面积、长距离和复杂状态管道的早期裂纹快速检测。而多模态超声导波管道检测技术,利用超声导波,基于小波分析、遗传算法和随机理论,研究激励的方法、信号的采集、分析和管道状态判别的理论和技术,可以实现这一目标。     

声表面驻波在微流控领域的应用

声表面驻波(SSAW)因其非接触性及生物相容性,目前已被广泛应用于微流控领域,在生物医学、诊断学等领域有着广阔的应用前景。概述了声表面驻波的形成过程和对微流体中粒子的控制机理;综合当前该技术国内外研究现状,分析了在微流控领域中声表面驻波相对于其他物理场的优势;针对声表面驻波在微流控领域中存在的问题对未来的研究提出了合理展望。     

Coupling and propagating of mesoscale sea level variability between the western Pacific and the South China Sea

The coupling and propagating features of mesoscale sea level variability between the western Pacific (WP) and the South China Sea (SCS) were studied based on time series analyses of satellite altimeter measured, along-track sea surface height anomalies (SSHA) along 21°N and the slope of the northern SCS. The analyses show that mesoscale sea level fluctuations in the WP have rather limited coherent effects on the SCS, and no statistically significant propagation of mesoscale variability through the Luzon Strait was observed except in the 45-day band. Evidence suggests that the 45-day fluctuation is very much likely a character of the Kuroshio originating from its low-latitude beginning. It is also sug- gested that the westward propagating Rossby waves will deform when they encounter the dynamical barrier of the Kuroshio. The Kuroshio will then acts on the SCS in its own way. The SCS is a relatively isolated system in the sense of coupling and propagating of oceanic mesoscale waves.     

压电体光滑接触界面上的滑移界面波理论分析

应用压电材料Stroh方法分析压电体光滑接触界面上滑移波的存在性条件,给出其存在的判据.压电体由外加单向压力作用而光滑接触,同时处于一定场强的电场中,设在波的作用下界面不会发生分离.通过具体压电材料的数值计算发现:当沿界面传播的波速满足一定条件时,滑移界面波能存在.特别地,两压电体的Rayleigh波速、极限波速一样时,滑移波将不存在;两压电体的Rayleigh波速、极限波速不同时,滑移界面波速将是两个Rayleigh波速之间的某个值或者是较小Rayleigh波速与较小的极限波速之间的值;滑移界面波的存在决定于材料本身的性质,而与外加载荷没有关系.     

Effect of cold spray particle conditions and optimal standoff distance on impact velocity

冷喷涂中,粒子撞击基板时的速度对涂层形成起到至关重要的作用,而适当的喷涂距离可以使喷涂粒子获得较高的速度.利用商用CFD软件Fluent模拟了喷嘴外超音速流场的分布情况,分析了粒子自身条件对冲击速度的影响,同时提出了确定粒子与基板最佳距离的方法.分析发现,小尺寸、低密度以及不规则形状的粒子容易受到喷嘴外产生的膨胀波、斜激波和基板前的弓形激波影响.随着能量的耗散或当粒子穿过弓形激波时,这些粒子的速度明显下降.另外,在基板与喷嘴之间存在一个最佳距离,它的确定需要两个必要条件：一是基板处的气流必须保持较低的速度,从而使弓形激波的强度相对较弱;二是粒子须经膨胀波加速2次,即弓形激波前具有2个膨胀波,以确保气体可充分利用膨胀波的加速.     

厚铝管中激光激发温度场和瑞利波的模拟

利用有限元方法数值模拟了脉冲激光作用于厚铝管时产生的温升以及由此温升而产生的表面瑞利波的情况。给出了温度随角向的分布曲线,比较了物理参数随温度变化和不随温度变化两种情况下温度场的区别,并进一步得到了近场区域表面波的时域波形。数值结果表明：在考虑材料物理参数随温度变化基础上得到的近场区域的表面声波中显著的波为掠面纵波和瑞利波,与平板中的类似。为热弹条件下管状材料的激光超声无损检测提供了参考。     

Seismic tomography of the Moon

We attempted to determine the first three-dimensional P and S wave velocity and Poisson＇s ratio structures of the lunar crust and mantle down to 1000 km depth under the near-side of the Moon by applying seismic tomography to the moonquake arrival-time data recorded by the Apollo seismic network operated during 1969 to 1977. Our results show that significant lateral heterogeneities may exist in the lunar interior. Because there is no plate tectonics in the Moon, the lateral heterogeneities may be produced at the early stage of the Moon formation and evolution, and they have been preserved till today. There seems to be a correlation between the distribution of deep moonquakes and lateral velocity variations in the lunar lower mantle, suggesting that the occurrence of deep moonquakes may be affected by the lunar structural heterogeneity in addition to the tidal stresses. Although this is an experimental work and the result is still preliminary, it indicates that tomographic imaging of the lunar interior is feasible.     

Fisher型方程的波前解及其波速(英文)

讨论了Fisher型方程波前解及其最小波速的存在性,并彻底讨论了当a→0时这些波前解及其最小波速之间的相互关系。