临界点附近气体热传导与粘度的特性和计算方法

应用限定立方模型参数标度状态方程和重整化群理论的一些结果,提出了奇异热传导和奇异粘度的计算公式与计算方法。该方法对热传导和粘度的工程计算具有足够好的正确度,同时又非常简便,从而具有很大的实用价值。对CO_2的计算结果与测量值之间的一致性是令人满意的。它们之间的偏差小于10％。

海洋工程力学

<正> 海洋工程力学是近几年随着生产和科学技术的蓬勃发展,随着人们的注意力逐渐转向海洋而兴起的一门新兴学科.它的诞生,就象一块巨大的磁石,立刻把许多国家的部门与学者紧紧地吸引在它的周围.

加卸载响应比在伊朗地区地震活动性研究中的应用

本文应用加卸载响应比理论,分别对2005年2月22日伊朗东南部克尔曼省扎兰德MS6.4地震和2006年3月31日伊朗西部洛雷斯坦省MS6.1地震2个震例进行了时程曲线分析;并用加卸载响应比方法对伊朗地区进行了时空扫描。通过考察加卸载响应比异常区域的演化过程,对该地区未来的地震活动性进行了研究。

矿场评价注水井伤害程度的试井方法

注水井试井是评价注水层伤害程度的有效手段。通过压力落差试井，可以测得注水井停注后压力随时间的变化，所得压力与时间关系的资料通过应用注水井不稳定试井解释方法，可以求得注水井的表皮因子，并通过表皮因子分析判断注水井伤害的主要原因。建立了试井评价模型，确定了压力落差试井表皮因子，现场应用后可以指出注水井伤害的程度和主要原因。

对数值模拟气相爆轰中二阶段化学反应模型再研究

采用改进的高精度时-空守恒元解元算法(the space-time conservation element and solution element method,CE/SE method)和考虑组分的二阶段化学反应模型(Sichel的二步模型)对气相爆轰问题的数值模拟进行了分析.分析发现采用Sichel的二步模型得到的数值结果虽然比早期二阶段化学反应模型(旧二步模型)更接近实验值,但是仍然不能得到爆轰过程准确气体动力学参数.为此通过修改组分的质量分数分布形式对Sichel的二步模型进行了改造,然后采用新的二步模型对平面爆轰波进行了数值模拟.数值结果表明采用新的二步模型计算得到气体动力学参数更接近于实验值和基元反应模型的计算值,在计算精度上有较大提高.

Relativistic channel-coupling focusing enhanced nonlinear guiding of an intense laser beam in a plasma channel

We employ the variational method to study the optical guiding of an intense laser beam in a preformed plasma channel without using the weakly relativistic approximation. Apart from the dependence on the laser power and the nonlinear channel strength parameter, the beam focusing properties is shown also to be governed by the laser intensity. Relativistic channel-coupling focusing, arising from the coupling between relativistic self-focusing and linear channel focusing, can enhance relativistic self-focusing but its strength is weaker than that of linear channel focusing. (C) 2008 Elsevier B.V. All rights reserved.

Electromagnetically induced negative refractive index in a V-type four-level atomic system

We propose a scheme for realizing negative refractive index in a V-type four-level atomic system. It is shown that the negative refractive index can be achieved in a wide frequency band based on the effect of quantum coherence. It is also found that the frequency band of negative refractive index and the absorption property of left-handed material are manipulated by the pump and control fields. Furthermore, left-handed material with reduced absorption is possible by choosing appropriate parameters. (c) 2006 Elsevier B.V. All rights reserved.

大型干涉仪镜子的支承设计与温度变形分析

在星间激光通信中，涉及对大口径衍射极限激光波面的检测，为保证测量精度，必须严格控制波面十涉仪镜子的自重和温度变形。采用有限元方法对大型干涉仪镜子在不同支承方式下的表面变形进行了分析，结果表明，接触角为180°的钢带支承是较好的支承方式，反射镜表面变形峰-谷(P-V)值仅为1．35nm，均方根(RMS)值为0．363nm根据这一结论，设计了一个同定支承点与浮动支承相结合的超静定钢带支承结构。在该结构下，分析了镜子轴向、径向、周向的温度梯度效应，分析数据表明，镜子的热弹性变形远大于自重变形，建议采取一定的温控

Simulation of an apodizer's effect for high-density optical storage

The effect of an apodizer with two parallel taper refractive surfaces is theoretically investigated for high-density optical storage. The apodizer may modulate an incident Gaussian beam into an annular beam. Simulation shows that with the increasing inner radius of the modulated beam, the focal spot shrinks obviously. The depolarization effect gets strong simultaneously, which induces the circular symmetry loss of the focal spot. In this process, pattern density of the orthogonal and longitudinal diffractive fields increases remarkably.

Broadband optical amplification near 1300 nm in bismuth-doped germanate glass

In this paper, we present the broadband optical amplification in bismuth-doped germanate glass, at the second telecommunication window when excited with 808 nm and 980 nm laser diodes, respectively. The amplification range is from 1272 nm to 1348 nm wavelength, which is within the O-band of silica fiber communication. This bismuth-doped glass can be used as ultra broadband amplification material for wavelength-division-multiplexing (WDM) at the second telecommunication window.

Growth of beta barium borate (beta-BaB2O4) thin films on alpha barium borate (alpha-BaB2O4) substrates

Crystalline beta-BBO thin films have been successfully prepared on (001)-oriented Sr2+-doped alpha-BBO substrates using liquid phase epitaxy and pulsed laser deposition techniques. The films were characterized by X-ray diffraction and X-ray rocking curve (XRC). The present results manifest that the beta-BBO thin films grown on Sr2+-doped alpha-BBO substrates have larger degree of orientation f-value and smaller XRC FWHM than the ones grown on other reported substrates. Compared with other substrates, alpha-BBO has the same UV cutoff and the similar structure to beta-BBO. These results reveal that alpha-BBO single crystal may be a promising substrate proper to the growth of beta-BBO films. (c) 2005 Elsevier B.V. All rights reserved.

Theoretical analysis of influence of substrate microdefects on polarized light properties of dielectric coatings

A model for refractive index of stratified dielectric substrate was presented according to inhomogeneous coatings theories. The substrate was divided into surface layer, subsurface layer and bulk layer along the normal direction of its surface. The former two layers were equivalent to inhomogeneous coatings. Theoretical deduction was executed by employing the characteristic matrix method of optical coatings, and one mathematical calculation example was presented. The results indicate that reflectance, reflective phase shift and phase difference of polarized light deviate from ideal conditions. It shows that substrate microdefects can induce volume scattering and change propagation characteristic of light both in coatings and substrate. (c) 2005 Elsevier GmbH. All rights reserved.