大带隙二维三角格子光子晶体结构参数的优化设计

光子晶体结构设计优化是理论研究的一个重要内容.运用平面波展开法对圆柱、方柱及正六边柱构造的二维三角格子光子晶体的禁带进行仿真计算,讨论了介质材料分别为GaAs、Si和Ge情况下,柱子形状、旋转角度、填充比的变化对完全光子禁带的影响.发现:对于二维三角格子光子晶体,相对于介质柱,空气柱更易获得完全光子禁带;而相对于圆柱及...     

一种新的自动聚焦算法的研究

聚焦评价函数和极点搜索策略是自动聚焦的重要模块,直接影响聚焦的效果.为同时满足自动聚焦速度和精度上的要求,提出了一种新的自动聚焦算法.该算法综合了快速改进的灰度差分法和高精度小波变换法的优点,根据各阶段聚焦评价函数的梯度选择合适的评价函数和镜头移动步长,并且实现了从大步长快速粗扫到小步长精确细调的过渡.实验表明,与传统...     

流动注射化学发光法测定山奈酚

采用流动注射技术,研究了高锰酸钾-山奈酚-过氧化氢体系的化学发光行为,对影响化学发光强度的因素进行了试验,建立了流动注射化学发光法测定山奈酚的新方法.方法检出限为1×10-10g·mL-1,线性范围为1.0×10-7-1.0×10-4g·mL-1.对1.0×10-6g·mL-1的山奈酚平行测定11次,其RSD为2.1%...     

Study of the THGEM detector with a reflective CsI photocathode

The THGEM detector without and with a CsI has been tested successfully. The optimal parame- ters of THGEM have been determined from eight samples. The UV photoelectric effect of the CsI photocathode is observed. The changing tendency related to the extraction efficiency (ε<,extr>) versus the extraction electric field is measured, and several electric fields influencing the anode current are adjusted to adapt to the THGEM detector with a reflective CsI photocathode.     

Theoretical study of the electronic ground states and low-lying singlet excited states of thiophene-based spirofluorenes

The electronic structures and optical properties of oligothiophene substituted spirofluorenes are investigated theoretically with semi-empirical quantum chemical calculations. A theoretical investigation of the interaction between two perpendicular π-systems of various oligothiophene substituted spirofluorenes is conducted. The results demonstrate that the interaction between two perpendicular branches is reduced by oligothiophene substitutions. Photoexcitation induced relaxation is mainly located on one of...     

惯性颗粒所见被动标量统计特性的DNS与模型研究

本文采用DNS方法,对惯性颗粒所见各向同性湍流中具有平均标量梯度的被动标量场统计特性进行了研究。结果表明：惯性对颗粒温度脉动强度,两相温度关联,自相关特性以及颗粒热流与两相交叉热流的统计特性具有明显的影响。在PDF方法的框架下,系统地推导了非等温气固两相流的PDF方程,且基于朗之万随机体系对方程进行了封闭,并利用前面的...     

纳米ZnO／石蜡复合相变材料的热物理性质研究

本文通过将纳米氧化锌（ZnO）颗粒加入熔融的石蜡（PW）并进行搅拌和超声制备了一种纳米ZnO／PW复合相变储能材料。为使纳米氧化锌在基体物质中分散均匀,在制备过程中使用了搅拌和超声以制备均匀的复合材料。使用扫描电镜观察其微观结构表明氧化锌在石蜡中分散良好。对所得ZnO／PW复合相变材料的相变温度、相变焓及导热系数等热物...