天然淡水冰单轴压缩强度及其温度和应变率效应

本文报道了在不同温度和不同应变率下天然淡水冰单轴压缩强度的实验结果。指出S—l型柱状晶粒冰的压缩强度随着温度的降低而增加,极限压缩强度在应变率为10~(-4)S(-1)时有一个最大值。本实验的应变率范围是10~(-5)—10~0s~(-1)。10~(-1)—10~0s~(-1)的应变率范围是在冲击速度lm/s左右的实验条件下获得的,这个速度接近于浮冰与海上结构物相撞的情况。以本实验为基础,有希望发展对海冰的实验技术。

正常固结饱和粘土的孔隙水压力

本文认为土体的剪胀性是偏应力的二次幂效应。根据这个假设,提出了孔隙水压力的计算公式。对正常固结饱和粘土的三轴不排水压缩试验结果进行了分析。分析结果表明,新的孔隙水压力公式合理地反映了正常固结饱和粘土的剪胀性。本文对土体的破坏问题也作了简要讨论。

硅对CO_2激光的增强吸收

测量离子注入硅片对强连续CO_2激光的透射率和反射率随辐照时间的变化,发现硅有极强的能量吸收。这一现象可定性地用自由载流子吸收来解释。

水冷式积分球功率计

本文介绍了用粗糙面作为漫反射面的水冷式积分球功率计。经标准能量计标定,具有响应时间快(10~(-1)秒)、重复性好(优于1%)、可测激光功率范围大(数瓦—千瓦)等特点。该功率计标定误差小于±5%,测量激光输出时,与国家标准大功率计之差在1%以内。

微孔法及干涉法在非稳定光学谐振腔调准中的应用

<正>由于非稳定腔具有大的可控模体积,采用共焦结构可以稳定输出平行光,准直后的光斑有最强的中心主瓣等优点,在大能量大菲涅耳数的激光器件中应用很广.但它的光学调准要求在10微弧度以上,因此,调准方法成为获得稳定运转的关键之一.本文介绍两种高精度调准方法.(1)微孔法:三个主要内容是微孔、叉丝和迭象.微孔在光学系统中可得到大的景深.通过微孔,人眼可看到叉丝的各次反射象迭合在一起,将它们按对接法对准可获得极高的调准精度.在正支非稳定腔结构的输出位置上设照明分划板.人眼通过微孔观察调准的各个阶段.最后使所有分划线的象重合在一起.

介绍激波管

<正> 一引言航空的发展不过是本世纪开端以来的事,年轻的航空技术成长很快,大约每十年就有一次划时代的进步。飞机已突破音速障碍而发展到超音速,有些先进国家正试造两倍音速的飞机(即飞行马赫数为2的飞机)。由于火箭及飞机等的速度愈来愈高,新的现象与困难也不断地产生。例如在高速飞行中,由于高速空气的动能在机身表面附近很薄的一层转变为热能,使飞机表面发高热:在两倍音速飞行时,机表面的温度已达300℃左右,而且机表面温度的增加是与飞行马赫数的平方成正比的,所以更进一步提高飞行

Dynamic analysis of arrest of buckle propagation on a beam on a nonlinear elastic foundation by FEM

Based on the dynamic governing equation of propagating buckle on a beam on a nonlinear elastic foundation, this paper deals with an important problem of buckle arrest by combining the FEM with a time integration technique. A new conclusion completely different from that by the quasi-static analysis about the buckle arrestor design is drawn. This shows that the inertia of the beam cannot be ignored in the analysis under consideration, especially when the buckle propagation is suddenly stopped by the arrestors.

Drop migration of middle Reynolds number in a vertical temperature gradient

The experimental investigation of the thermocapillary drop migration in a vertical temperature gradient uns performed on ground. Silicon oil and pure soybean oil were used as experimental medium in drops and as continuous phases, respectively, in the present experiment. The drop migration, under the combined effects of buoyancy: and thermocapillarity, was studied for middle Reynolds numbers in order of magnitude O(10(1)). The drop migration velocities depending on drop diameters were obtained. The present experimental results show relatively small migration velocity in comparison with the one suggested by Young et nl. for linear theory of small Reynolds number. An example of flow patterns inside the drop was observed by PIV method.

Numerical study of bluff body flow structures

Our recent progress in numerical studies of bluff body flow structures and a new method for the numerical analysis of near wake flow field for high Reynolds number flow are introduced. The paper consists of three parts. In part one, the evolution of wake vortex structure and variation of forces on a flat plate in harmonic oscillatory flows and in in-line steady-harmonic combined flows are presented by an improved discrete vortex method, as the Keulegan-Carpenter number (KC) varies from 2 to 40 and ratios of U-m to U-0 are of O(10(-1)), O(10) and O(10), respectively. In part 2, a domain decomposition hybrid method, combining the finite-difference and vortex methods for numerical simulation of unsteady viscous separated flow around a bluff body, is introduced. By the new method, some high resolution numerical visualization on near wake evolution behind a circular cylinder at Re = 10(2), 10(3) and 3 x 10(3) are shown. In part 3, the mechanism and the dynamic process for the three-dimensional evolution of the Karman vortex and vortex filaments in braid regions as well as the early features of turbulent structure in the wake behind a circular cylinder are presented numerically by the vortex dynamics method.

The induction plasma chemical reactor: Part I. Equilibrium model

A mathematical model is presented for the numerical simulation of the flow, temperature, and concentration fields in an rf plasma chemical reactor. The simulation is performed assuming chemical equilibrium. The extent of validity of this assumption is discussed. The system considered is the reaction of SiCl4 and NH3 for the production of Si3N4.

The induction plasma chemical reactor: Part II. Kinetic model

A kinetic model has been developed for the prediction of the concentration gelds in an rf plasma reactor. A sample calculation for a SiCl4/H2 system is then performed. The model considers the mixing processes along with the kinetics of seven reactions involving the decomposition of these reactants. The results obtained are compared to those assuming chemical equilibrium. The predictions indicate that an equilibrium assumption will result in lower predicted temperature fields in the reactor. Furthermore, for the chemical system considered here, while differences exist between the concentration fields obtained by the two models, the differences are not substantial.

Resumen de las Memorias de Jaime de Urkijo, por Luis Ruiz de Aguirre.

Fecha: >1970 / Unidad de instalación: Carpeta 53 - Expediente 10-1 / Nº de pág.: 14 (manuscritas)

第57届国际宇航大会会议介绍

1概况 第57届国际宇航大会于2006年10月2—6日在西班牙瓦兰西亚召开，10月1日还召开了国际宇航科学院院士会和国际宇航学会各委员会会议．会议参加人数超过2000人，开幕式大礼堂座无虚席．这次会议的主题是“开创更贴近人民的空间事业（bringing space closer to people）”．大会在瓦兰西亚的大展览馆召开，群众与代表交混．除大会会场外，所有分会会场都是用木板临时安装的，会场条件简单．