Rarefied Gas Flows in Micro-Channels

利用基于分子模型的统计模拟方法--信息保存方法(IP)统计模拟了实验条件下微槽道气体流动,仔细讨论了用IP方法模拟长槽道稀薄气流时遇到的问题,并给出了解决的方法,即采取守恒形式的控制方程避免质量流量计算误差积累,并利用超松弛方法使收敛过程加速。将IP计算结果与压力分布和质量流量实验数据进行了比较。

Reflection of shock-wave in pur foam from rigid wall

Keller proposed that a building, a mechanical installation or a body wrapped bya layer of foam plastics may be an efficient means for protection from damage ofblast wave. However, the practical effect was beyond expectation. For example, agunner wearing the foam plastics-padded waistcoat was injured more seriously by theblast wave from a muzzle. Monti took the foam plastics as homogeneous two-phasemedium and analyzed it with the theory of dusty flow. The obtained results showthat the peak pressure behind the reflected shock wave from rigid wall with foamcoat exceeds obviously that without foam coat under the same condition. Gel'fand,Patz and Weaver made experimental observations by means of shock tubes and veri-

非平整、多孔介质海底上波浪传播的复合方程

为了反映近岸区域实际存在的多孔介质海底效应,并且考虑到波浪在刚性海底上传播模型的最新研究进展,运用Green第二恒等式建立了波浪在非平整、多孔介质海底上传播的复合方程.假设水深和多孔介质海底层厚度均由两种分量组成:慢变分量,其水平变化的长度尺度大于表面波的波长;快变分量,其水平变化的长度尺度与表面波的波长等阶,但其振幅小于表面波的振幅.另外,多孔介质层下部边界的快变分量比水深的快变分量小1个量级.针对水体层和多孔介质层,选择Green第二恒等式方法给出了波浪传播和渗透的复合方程,它在交接面上满足压力和垂直渗透速度的连续性条件,可充分考虑波数变化的一般连续性,并包含了某些著名的扩展型缓坡方程.

Effects of rainfall infiltration on the stability of soil slopes

Slope failure due to rainfall is a common geotechnical problem. The mechanics of rainfall induced landslides involves the interaction of a number of complex hydrologic and geotechnical factors. This study attempts to identify the influence of some of these factors on the stability of soil slope including rainfall intensity, hydraulic conductivity and the strength parameters of soil.

高功率脉冲氙灯的动态PSpice模型研究

根据气体放电相关理论建立高功率脉冲氙灯仿真模型，阐述了放电回路设计的基本原理，采用建立的模型通过计算机对TIL及NIF装置进行仿真，给出了放电回路的仿真结果，与装置运行实际数据比较发现仿真模型及过程可靠，为高功率激光装置的电子计算机辅助设计和分析提供了一种新途径。

Fluorescence lifetime increasing with F- ions into ytterbium-doped germanium-lead-tellurite glasses

The effects of F- ions in a germanium-lead-tellurite glass system oil the spectral and potential laser properties of the Yb3+ are investigated. The absorption spectra, lifetimes, the emission cross-sections and the minimum pump intensities of the glass system with and without F- ions have been measured and calculated. The results show that the fluorescence lifetime and the minimum pump intensity of Yb3+ ions increase evidently, which indicates that germanium lead-oxyfluoride tellurite glass is a promising laser host matrix for high power generation. FT-IR spectra were used to analyse the effect of F- ions on OH- groups in this glass system. Analysis demonstrates that addition of fluoride removes the OH- groups and results in improvement of fluorescence lifetime of Yb3+.

LD抽运Yb:GSO实现1090nm低阈值激光运转

We report what we believe to be the first demonstration of laser operation with a novel laser material of Yb3(+) -doped Gd-2 SiO2 (Yb: GSO) pumped by a laser diode at 940 nm. We obtained a low lasing threshold of 1.27 kW/cm(2) with the center wavelength of 1090 nm, which is lower than the value of 1.53 kW/cm(2) predicted for Yb: YAG. The maximal output power of 360 mW was obtained with a 2% output, which corresponds to a slope efficiency up to 19%.