双过临界喷管充气混合装置

双过临界声速喷管充气混合装置能够快速、均匀地混合两种气体，其背压适用范围比临界声速喷管提高了40%，性能良好，结构简单。经边界层修正、实态标定和色谱检验，混合效果良好。适用于各种燃烧、爆轰实验的气体混合。

用形变理论分析结构塑性屈曲时的一类广义变分原理

本文给出了用形变理论分析结构塑性屈曲时的一类广义变分原理,说明了它在本质上的势能意义。在广义变分形式下论证了塑性屈曲时无卸载的根据。最后在简化加筋板壳的分析中作了应用示例。

大块金属玻璃中由热软化和自由体积产生诱导的剪切带行为比较

比较研究了大块金属玻璃中由热软化和自由体积产生诱导的剪切带行为.首先讨论了大块金属玻璃中剪切失稳的热软化和自由体积产生效应.众所周知,在普通金属材料中,由塑性功转变来的热是其形成热塑剪切带的主要原因,并且是与能量直接相关的.与热软化相比,自由体积产生是金属玻璃发生剪切失稳的另外一种主控因素,由自由体积产生诱导的剪切失稳与由热软化诱导的剪切失稳完全不同,失稳判据中不显含能量.尤其是自由体积产生时的长波扰动总是不稳定的.从而,由自由体积产生和热软化耦合时的剪切失稳更像是由自由体积产生引发的.同时,在金属玻璃中,复合自由体积产生提供了一种特殊和内在的剪切失稳特征生长时间.剪切带的特征宽度由剪切带内相应的扩散过程控制:热扩散和自由体积扩散.作为粗略的估计,用无量纲数B,Deborah数(表示失稳生长率和载荷时间关系)和Lewis数(表示不同扩散竞争)表示了热软化和自由体积产生在剪切带形成过程中的相对重要性.这些结果对于理解大块金属玻璃剪切带形成机理具有非常重要的意义.

Laminar Burning Velocities and Markstein Lengths of Premixed Methane/Air Flames near the Lean Flammability Limit in Microgravity

Effects of flame stretch on the laminar burning velocities of near-limit fuel-lean methane/air flames have been studied experimentally using a microgravity environment to minimize the complications of buoyancy. Outwardly propagating spherical flames were employed to assess the sensitivities of the laminar burning velocity to flame stretch, represented by Markstein lengths, and the fundamental laminar burning velocities of unstretched flames. Resulting data were reported for methane/air mixtures at ambient temperature and pressure, over the specific range of equivalence ratio that extended from 0.512 (the microgravity flammability limit found in the combustion chamber) to 0.601. Present measurements of unstretched laminar burning velocities were in good agreement with the unique existing microgravity data set at all measured equivalence ratios. Most of previous 1-g experiments using a variety of experimental techniques, however, appeared to give significantly higher burning velocities than the microgravity results. Furthermore, the burning velocities predicted by three chemical reaction mechanisms, which have been tuned primarily under off-limit conditions, were also considerably higher than the present experimental data. Additional results of the present investigation were derived for the overall activation energy and corresponding Zeldovich numbers, and the variation of the global flame Lewis numbers with equivalence ratio. The implications of these results were discussed. 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

太湖风生流特征的数值模拟研究

该文基于对太湖地形和水动力特征的分析,建立了沿垂向平均的太湖二维浅水动力学模型,给出了模型参数和模型的数值求解方法.通过对太湖风生流的模拟,分析了太湖风生环流的基本形态特征,并得到了实测流场的良好验证.进一步对盛行风场下的太湖流场和水动力特征进行数值研究表明,太湖风生流的形成主要由风场、湖泊边界及湖底地形决定;得到了不同湖区的流动规律和水动力特征,并揭示了不同湖区流动差异的形成原因.

Enhancement and broadening of extreme-ultraviolet supercontinuum in a relative phase controlled two-color laser field

We experimentally demonstrate the generation of an extreme-ultraviolet (XUV) supercontinuum in argon with a two-color laser field consisting of an intense 7 fs pulse at 800 nm and a relatively weak 37 fs pulse at 400 nm. By controlling the relative time delay between the two laser pulses, we observe enhanced high-order harmonic generation as well as spectral broadening of the supercontinuum. A method to produce isolated attosecond pulses with variable width and intensity is proposed. (C) 2008 Optical Society of America.

Observing the fractional Fourier transform by free-space Fresnel diffraction

The fractional Fourier transform of an object can be observed in the free-space Fresnel diffraction pattern of the object. (C) 1997 Optical Society of America

低损耗有机无机混合溶胶凝胶波导的实验研究

利用有机无机混合的溶胶凝胶方法在硅基底上制备波导薄膜．采用正硅酸四乙酯和苯基三乙氧基硅烷作为反应先驱物，利用旋涂的方法成膜，对其折射率，传输损耗以及条形波导的光刻、刻蚀特性进行了研究．测量了波导薄膜折射率随成分变化的关系．实验表明，该方法工艺简单，可以获得具有较低损耗的波导薄膜．测试得到632．8nm波段的损耗系数为0．23dB／cm．采用ICP刻蚀工艺获得了较为平整的条形波导．

Control of polarization signal distortion by frequency domain phase conjugation in optical fiber systems

Optical frequency domain phase conjugation (FDPC) is based on phase conjugation of spectrum of an input signal. It is equivalent to the phase conjugation and the time reversal of the temporal envelope of an input signal. The use of FDPC to control polarization signal distortion in birefringent optical fiber systems is proposed. Evolution of polarization signals in the system using midway FDPC is analyzed theoretically and simulated numerically. It is shown that the distortion of polarization signals can be controlled effectively by FDPC. The impairments due to dispersion and nonlinear effects can be suppressed simultaneously.

579．62nm波长处Y2SiO5：Eu^3＋晶体永久性光谱烧孔

分别利用氩离子激光，二倍频YAG：Nd激光泵浦的诺明6G可调谐窄线宽（0．5cm^-1）染料激光和899-21可调谐染料激光作为光源，以单色仪-锁相放大器-光电倍增管-计算机数据采集系统记录光谱，对Y2SiO5：Eu^3＋晶体进行了光谱和光谱烧孔研究。在常温和液氮温度下测量了晶体的激发光谱、荧光光谱等。在16K温度下对晶体进行了光谱烧孔研究，得到了孔宽约80MHz并能保存10h的永久性光谱孔。