Temperature factor effect on the structure of the separated flow within a supersonic gas stream

The effect of the temperature factor, that is, the ratio of the body temperature to the freestream stagnation temperature, on the structure of the separated flow formed in the presence of a concave corner in a supersonic stream is studied. The strong influence of the temperature factor on the separation zone length and the flow-generated aerodynamic characteristics is established. It is shown that for fairly large deflection angles this flow cannot be described by free interaction, or triple deck, theory.     

基于积分方法的二维平行剪切层声远场预测

本文采用二维Ffowcs Williams＆Hawkings(FW-H)方程对平行剪切层远声场辐射特性进行了研究。近流场时间精确数据通过计算气动声学(Computational Aeroacoustics,CAA)技术数值模拟获得,声远场信息则通过FW-H方程对近流场内的可穿透积分面进行积分获得。该方法首先采用具有解析解的涡/尾缘干涉问题进行了校核,进一步采用CAA/FW-H匹配技术对二维平行剪切层声辐射问题进行了预测,计算结果表明,积分解与计算域内的CAA数值解吻合较好。     

胶束薄层色谱法测定食品及药用胶囊中的合成食用色素

在聚酰胶片上以13%SDBS(十二烷基苯磺酸钠)+7%Triton X-100〔聚乙二醇-对-(1.1,3,3-四甲基)丁基苯基醚〕+(2+3)氨水(1+5+1)为展开剂,用胶束薄层色谱法分离和测定了柠檬黄、亮蓝、苋菜红、胭脂红和赤藓红。测定波长分别为440、632、535、525和528 nm,线性范围分别为0.1～2、0.05～1、0.05～1、0.05～1和0.05～1μg/斑点。方法用于测定软饮料糖果及药用胶囊中的合成色素,获得了满意的结果。此外,还对展开剂的最佳组成进行了单纯形法优化。     

世界经济层内进化浅论

本文将物理系统层内进化扩展到世界经济系统中去，通过对世界经济循环结构与物理系统进化的层次结构关系的探讨，论述了世界经济周期的特征及经济周期的熨平作用。     

Asymptotic analysis and estimates of blow‐up time for the radial symmetric semilinear heat equation in the open‐spectrum case

We estimate the blow‐up time for the reaction diffusion equation u_t=Δu+ λf(u), for the radial symmetric case, where f is a positive, increasing and convex function growing fast enough at infinity. Here λ>λ^*, where λ^* is the ‘extremal’ (critical) value for λ, such that there exists an ‘extremal’ weak but not a classical steady‐state solution at λ=λ^* with ∥w(?, λ)∥_∞→∞ as 0<λ→λ^*?. Estimates of the blow‐up time are obtained by using comparison methods. Also an asymptotic analysis is applied when f(s)=e^s, for λ?λ^*?1, regarding the form of the solution during blow‐up and an asymptotic estimate of blow‐up time is obtained. Finally, some numerical results are also presented. Copyright © 2007 John Wiley & Sons, Ltd.     

W_(18)Cr_4V钢真空油淬白亮层、熔化层形成原因的试验研究

W_(18)Cr_4V钢真空加热油淬后,表面出现白亮层和熔化层等异常现象。本文利用金相显微镜,显微硬度计、扫描电子显微镜和电子探针等手段对白亮层和熔化层进行了分析研究。试验表明,白亮层、熔化层均是真空油淬增碳的结果。本文对白亮层、溶化层形成原因进行了比较深入的分析探讨提出了产生白亮层必须同时具备的三个条件。     

Number albedo measurements from stratified layers of iron,concrete and aluminium

A layer of stratified combination composed of selected radiation shielding materials acquires better shielding property. Albedo is used in such measurements as an integral measure ofγ-ray scattering. The stratified slabs of alternating heterogeneous layers have been found to have a virtual homogeneous property with a definite effective atomic number. The angular distribution of back-scattered photons as well as the total number albedo values for iron, aluminium and concrete in stratified combination for 662 keV and 1250 keV photons are reported.     

分段函数的分类及分离型分段函数与初等函数之间的关系

将分段函数划分为连结型分段函数 ,分离型分段函数和它们的组合形式三种类型 ,得到了分离型分段函数是初等函数的充分必要条件 ,完整地解决了分离型分段函数与初等函数之间的关系 ,并且给出了初等函数在其任一截取集上的限制函数 (截取函数 )仍然是初等函数的结果     

Ge_x Si_(1-x)/Si超晶格中纵声学声子的喇曼散射强度研究

本文用光弹理论,在全面考虑了超晶格中两种材料的声速,质量密度和光弹常数存在差别的基础上,计算了Ge_xSi_(1-x)/Si超晶格中折迭纵声学声子的喇曼散射强度,在高达50cm~(-1)的频率范围内,理论值和实验符合得很好。     

一个临界情形的奇摄动拟线性二阶方程组的狄利克雷问题

研究了临界情形的拟线性二阶方程组的狄利克雷问题，证明了狄利克雷问题解的存在唯一性，并给出解的渐近展开式及余项，估计式．