Modelling of streaky structures and turbulent-spot generation process in wing boundary layer at high free-stream turbulence

Results of an experimental study of turbulent breakdown in gradient boundary layer at high freestream turbulence are reported. For the first time it is shown that, like the flat-plate boundary layer, the wing boundary layer at high freestream turbulence is modulated with streaky structures. One of possible mechanisms underlying the generation of turbulence spots in wing boundary layer is modelled assuming the interaction of streaky structures with high-frequency waves. Qualitative and quantitative data concerning the evolution of streaky structures in swqpt-wing boundary layer and in swept-wing boundary layer are presented. Certain differences between the evolution of streaky structures in wing boundary layer and in flat-plate boundary layer are revealed. This work was supported by the President of the Russian Federation (Grants NSh-454.2008.1, MK- 101.2007.1), by the Russian Foundation for Basic Research (Grant No. 05-01-00034), by the Ministry of Education and Science of the Russian Federation (Grant No. RNP 2.1.2.3370), and by the Russian Government (State Contract No. 02.513.12.0043).     

冲击作用下纳米孔洞动力学行为的多尺度方法模拟研究

本文利用多尺度方法研究了包含孔洞金属材料在冲击加载条件下的动力学行为. 该多尺度方法结合了分子动力学和有限元方法,分子动力学方法运用于局部缺陷区域,而有限元方法运用于整个模型区域,两种方法之间使用桥尺度函数进行连接. 计算结果既包括了系统宏观的物理信息,如应变场、应力场、温度场等,也得到了微观原子的物理信息,如原子能量和位置坐标等. 结合以上的模拟结果,发现孔洞的坍塌与材料屈服强度和冲击强度有关,而孔洞坍塌和坍塌过程中对微喷射原子的压缩过程是形成局部热点的主要原因. 同时也发现孔洞坍塌形成的位错和局部热点可以导致局部绝热剪切带更容易形成. 关键词： 微孔洞 热点 冲击加载 多尺度方法     

HER磁镜上硬X射线和热电子测量

一、引言 磁镜运行中,为了要知道它在电子回旋共振加热(ECRH)下形成热电子的参数,我们测量了硬X射线能谱、硬X射线发射的时间特性、不同磁场强度下形成热电子环的位置、以及热电子的脉冲幅度分布等。 HER是中国科学院等离子体物理研究所简单型磁镜装置,它的几何尺寸是,真空室长     

中国聚变工程实验堆水冷包层钢构件流道成形控制研究

针对CFETR水冷包层流道钢构件热等静压制备时易变形压塌问题,利用单轴扩散焊设备开展了焊接工艺参数优化试验。在此基础上,重新设计了流道焊接界面位置和尺寸,用两步热等静压扩散焊法制备出了流道变形可控的平板型第一壁钢构件模块。优化试验表明,低活化钢试样的固相扩散焊温度需高于950℃,焊后经过760℃/60min回火热处理试样力学性能可以得到有效回复。     

利用亮度波形证明固态阴极射线发光

制备了3种结构的器件：A: ITO/SiO₂/Alq₃/Al, B: ITO/Alq₃/SiO₂/Al,C: ITO/SiO₂/Alq₃/SiO₂/Al。对于器件A和B,在正向偏压(ITO接正极)下才能观察到发光;而对于器件C,在正向和反向偏压下都可以观察到发光。随着电压升高,器件B和C产生的蓝色发光相对绿光逐渐增强。这主要是由于SiO₂中的加速电子碰撞激发Alq₃发光层产生热电子,并与空穴形成电子空穴对,复合产生蓝光;而对于器件A,在反向偏压下被热电子碰撞激发出的空穴与正向偏压下从Al电极进入的电子复合形成激子,产生绿色发光。这些结构的器件发光不但可来源于电子与积累的空穴复合,而且也来自固态阴极射线发光。     

“Hot Potato Voice” in Peritonsillitis: A Misnomer

The "hot potato voice" is widely recognized as a symptom of peritonsillar cellulitis or abscess; yet there have been no studies assessing the resonance characteristics of the vocal tract in peritonsillitis. Analysis was undertaken of formant frequencies in the articulation of the vowels /i:/. /a:/ and /u:/ in six subjects with peritonsillitis and compared with articulation once the peritonsillitis had settled. Significant variation was found in F1 when articulating /i:/ and in F2 when articulating /a:/, which are explainable by dyskinesis of the peritonsillar musculature. These findings were compared with six subjects articulating the same vowels with and without a hot potato in their mouth. Variation was found in both F1 and F2 when articulating /i:/, which can be related to interference of the potato with movement of the anterior tongue. The changes in the vocal tract differ in these two cases and the title "hot potato voice" in peritonsillitis is a misnomer.     

惯性约束聚变装置中靶面光场特性的统计表征方法

在激光驱动的惯性约束聚变装置中,常采用多种束匀滑手段对焦斑的时空特性进行调控.光传输链路中涉及的光学元件众多、传输变换复杂,往往导致光传输模型复杂,且在运用衍射光学方法分析焦斑形态和特征时面临大量的数据处理和计算,致使出现计算量大、计算效率低等问题,亟需寻求快速而简便的新方法来描述焦斑的统计特征.本文利用光场特性的统计表征方法对靶面光场进行表征,采用圆型复数高斯随机变量直接描述靶面光场的统计特征,并基于典型焦斑评价参数对衍射光学方法和统计表征方法得到的远场焦斑进行了对比和分析.结果表明,采用衍射光学方法和统计表征方法获得的焦斑的瞬时特征基本一致,其时间积分的远场焦斑有所不同,但仍可进一步采用相关系数来表征其远场焦斑的时间变化特征.     

First Experience in Using Microdensitometer “Scandig 3” — Joyce Loebl for Autoradiographs Evaluation

The Device is composed of the basic microdensitometer, the control computer, the magnetic tape unit, the teletype, the interface, and the software package.

This apparatus is designated for digitalization of image data point by point (system “flying spot”) and for their record on magnetic tape for further data processing. The software package makes possible to realize some basic evaluation only by using configuration mentioned above — for example recording of measured values, determination of numbers of occurrences particular optical density (histogram), tresholding and mapping of measured values.

This paper describes the instrument and its using for autoradiographs evaluating.     

Influence of chemistry and hot rolling conditions on high permeability non-grain oriented silicon steel

This paper discusses the influence of chemical composition on the final electromagnetic properties in higher permeability material. Furthermore, the effect of the hot rolling practice and the end of austenite transformation temperature range on the hot band microstructure is described. The magnetic polarization J₅₀₀₀ better than 1.7 T, using hot rolling conditions 40 mm transfer bar thickness, finish mill entry temperature 1000 °C, and finishing temperature 800–840 °C and after decarburization heat treatment and grain growth treatment, was obtained.     

参数可控长距无衍射光束的生成方法研究

为了消除光学器件几何参数对无衍射光束传播特性调整的限制,实现长距空间中无衍射光束传播时特性参数的可控性,首先,通过研究axicon折射阴影区的电场分布特征,发现axicon无衍射区外过临界面后的近轴区域虽处于几何折射阴影近轴区域内,但仍存在光强服从第一类零阶贝赛尔函数分布的球面波;以此为基础,提出了一种不受传播空间距离限制的无衍射光束的生成方式;最后,在近12 m的尺度范围内进行无衍射光传播特性参数测试,发现其实验参数与理论计算值的差值不超过0.1μm。该无衍射光通过对第一类零阶贝塞尔函数分布的球面衍射光斑准直生成,本质上区别于传统的干涉无衍射光束生成方式,易于生成大尺度空间无衍射光束。该无衍射光生成方式适合用于非能量使用情况下大尺度空间的直线基准、光束空间通讯等领域,具有较大的价值与意义。