沙丘粗糙面的二次极化电磁散射

研究了新月形沙丘粗糙面的二次极化电磁散射. 结合射线追踪理论, 由一次散射面元的反射场照射到二次散射面元, 采用基尔霍夫近似推导了二次散射面元的二次极化散射场. 计算结果表明二次极化散射结果在特定的角度和类型范围内有显著影响. 在电磁波射向背风坡时可以发现其同极化散射截面在入射角较大时大于其他入射方向的结果, 入射角在休止角附近时的交叉极化散射截面出现峰值, 以及前后狭长沙丘之间的二次极化散射特别突出. 本文结果可用于反演分析沙漠地区的风场信息. 关键词： 新月形沙丘 二次极化散射 射线追踪 休止角     

鱼眼镜头的光路追迹

鱼眼镜头的视场角高达180或超过180°，运用通常的光路计算程序无法对鱼眼镜头进行光路追迹。本文介绍先借用尝试光线确定一个适当的起始点，然后用迭代法计算出主光线和边缘光线的位置，最后给出计算实例。     

Aspherical lens shapes for focusing synchrotron beams

Aspherical surfaces required for focusing collimated and divergent synchrotron beams using a single refractive element (lens) are reviewed. The Cartesian oval, a lens shape that produces perfect point‐to‐point focusing for monochromatic radiation, is studied in the context of X‐ray beamlines. Optical surfaces that approximate ideal shapes are compared. Results are supported by ray‐tracing simulations. Elliptical lenses, rather than parabolic, are preferred for nanofocusing X‐rays because of the higher peak and lower tails in the intensity distribution. Cartesian ovals will improve the gain when using high‐demagnification lenses of high numerical aperture.     

劳厄弯晶光学特性的光线追迹研究

基于X射线几何衍射的晶层模型,编写了用于柱面弯曲劳厄晶体的光线追迹软件.程序主体用C语言编写,在VC++环境下运行.利用程序分别对衍射光方向和能量带宽两方面不同的项目进行追迹,通过模拟结果与理论计算和实验结果的对比,显示出很好的一致性,从而验证了程序在追迹衍射光衍射方向变化和能量变化方面的正确性.利用该光线追迹软件,追...     

Dynamic Simulation of the Electron Bernstein Wave Heating Under NBI Conditions in TJ–II Plasmas

In this work, we have calculated the expected properties of the Electron Bernstein Wave (EBW) heating using the O–X–B double mode conversion scenario in a plasma that evolves from Electron Cyclotron Resonance (ECR) to Neutral Beam Injection (NBI) heating in the TJ–II device. For this purpose, a transport simulation that reproduces the time evolution of a typical collapsing plasma heated by a combination of ECR and NBI power has been used. It is seen that the predicted EBW absorption depends strongly on the plasma characteristics, whose time evolution depends in turn on the heating properties. Therefore, the need of consistently computing the ray tracing and the plasma evolution is underlined. The fraction of the absorbed EBW heating power becomes very high as soon as the O mode cutoff layer appears. This guarantees the overlapping of both EBW and ECR heating, thus avoiding excessive plasma cooling when the wave cutoff is reached. The EBW power deposition profile evolves from off‐axis to a much more centred shape that persists until the radiative collapse quenches the plasma (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

软x射线平场光谱仪系统的优化设计

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高温变形测量中热流场造成畸变的修正方法

目前高温环境中材料的变形测量是研究的热点,基于数字图像特征识别的非接触测量方法促进了高温环境变形测量的发展,但由于高温环境的复杂性,存在很多测量影响因素,其中高温环境中热流场的存在对数字图像法的影响尤为明显。本文提出了一种对高温变形测量中热流场造成畸变影响的修正方法。针对基于光学成像方法的材料高温变形测量中常见的热流场扰动,通过数值仿真得到热流场模型及热流场分布状况,再结合光线追迹原理对热流场造成的图像畸变影响进行分析,用数值分析结果对高温变形测量实验结果进行修正。对比扰动修正结果与真实位移有很好的一致性,从而证明了所提方法的可行性和有效性。     

The acoustical influence of balcony depth and parapet form: experiments and simulations

The influence of balcony depth and parapet form on the acoustical performance of building facades close to roadways have been investigated. Various depths and two inclinations of parapet have been modeled on an eight floor building. Pyramid ray-tracing simulations and scale model measurements have been carried out. The predicted and measured A-weighted sound pressure level reductions over the balcony back wall and in free field conditions have been compared. The results have been used to derive empirical equations for predicting protection as a function of geometrical parameters. The protection obtained by various parapet depths ranges between 4 and 8 dB(A), while an additional protection of between 0.5 and 4 dB(A) can be obtained by inclining the parapets.     

Analysis of laser drilled deep holes in stainless steel by superposed pulsed Nd:YAG laser radiation

Deep drilling of through holes in stainless steel (1.4301, sample thicknesses 5, 8 and 10 mm) has been performed with the superposed radiation of two pulsed Nd:YAG lasers with pulse duration of 0.5 ms superposed by 17 ns pulses. The drilling efficiency is improved by the spatially and temporally superposed radiation of the two lasers. The enhanced drilling speed and the larger reproducibility of the drilling time are explained by a modified formation of closures in the hole during percussion drilling which are recorded by high-speed photography. The metallographic hole analysis exhibits high-temperature oxidation marks. The development of these marks is described by a ray tracing of the incident beam within the hole and the resulting intensity distribution at the hole wall.     

偶氮类化合物在纳米TiO2表面光降解的UV-Vis光谱示踪研究(Ⅰ)--中间体的发现及动力学行为

用UV-Vis吸收光谱和差谱考察了以DBC-偶氮羧为主的5种偶氮化合物在纳米TiO2表面光降解的动力学行为和电子转移历程,载荷子的捕获经历一个中间过程,最终矿化为无机物.按误差补偿理论拟合的中间体峰形曲线和实验c～t图平行吻合,获得了相应的动力学参数.推测了电子转移的可能途径.