介质折射率对一维三元光子晶体带隙的影响

利用光学传输矩阵法,数值模拟了一维二元、三元光子晶体的带隙结构,得出:三元光子晶体的主带隙略宽于二元光子晶体的主带隙;三元光子晶体的主带隙主要取决于最高折射率的介质和最低折射率的介质,而与居于两者之间的介质关系不大,并作出了相应的关系曲线。最后推导了三元光子晶体的色散关系。     

The polar ionosphere at Zhongshan station on May 11, 1999, the day the solar wind almost disappeared

The solar wind almost disappeared on May 11, 1999: the solar wind plasma density and dynamic pressure were less than 1cm⁻³ and 0.1 nPa respectively, while the interplanetary magnetic field was northward. The polar ionospheric data observed by the multi-instruments at Zhongshan Station in Antarctica on such special event day was compared with those of the control day (May 14). It was shown that geomagnetic activity was very quiet on May 11 at Zhongshan. The magnetic pulsation, which usually occurred at about magnetic noon, did not appear. The ionosphere was steady and stratified, and the F₂ layer spread very little. The critical frequency of day-side F₂ layer, f₀F₂, was larger than that of control day, and the peak of f₀F₂ appeared 2 hours earlier. The ionospheric drift velocity was less than usual. There were intensive auroral E_s appearing at magnetic noon. All this indicates that the polar ionosphere was extremely quiet and geomagnetic field was much more dipolar on May 11. There were some signatures of auroral substorm before midnight, such as the negative deviation of the geomagnetic H component, accompanied with auroral E_s and weak Pc3 pulsation.

     

O′-β′复相Sialon陶瓷中相组成的控制

用Si₃N₄,SiO₂和Al₂O_?作原料,以Y₂O_?为添加剂,研究了O’-β’所在的四个相容性区中组成,于1400—1800℃之间,O’和β’的形成动力学。O’于1400℃开始生成,1600℃达到最大形成量。高于1600℃,O’减少乃至消失。研究发现,O’的这种不稳定性,并非自身热分解的结果。Al含量的增加,液相出现和β’的形成,才是导致O’-Sialon溶解而消失的原因。 此外,认为Si₃N₄-O’(x=0.3)-Y₂Si₂O₇-YAG相容性区,是在制备具有合理的O’-β’平衡相组成的复相陶瓷时,可供实际选用的组成区。     

The effects of doubly excited states on ionization balance

The effects of highly doubly excited states on ionization balance are investigated. In the calculation, A Collisional-Radiative model in Detailed-Configuration-Accounting (DCA) is applied to population calculations for NLTE plasmas. Configuration-averaged rate coefficients that needed in the rate equations are obtained based on the first order perturbation theory. The Hatree-Fock-Slater self-consistent-field method is used to calculate the electron wave functions. The mean ionization stage of high-Z plasma Lu is presented. The comparison shows that the mean ionization stage increases more than 3 stages when doubly excited states 5l6l' and 5l5l' are not included in the population calculations.     

物体内部三维位移场分析的数字图像相关方法

提出了物体内部三维位移场的数字图像相关分析方法，对物体变形前后，或连续变形的两个相邻状态的内部三维结构的数字图像，通过相关运算获得三维位移场.文中给出了三维相关法的体搜索窗口、相关函数及亚像素运算的相关系数拟合函数.数字模拟结果证明了三维相关法的正确性及可靠性.位移计算精度为0.02像素. 关键词： 数字图像相关 三维相关 亚像素     

LD泵浦Nd∶LuVO4/Cr4+∶YAG被动调Q激光器

采用大功率半导体激光器端面泵浦Nd∶LuVO4晶体，利用Cr4+∶YAG晶体作为可饱和吸收元件，实现了1.06 μm激光的被动调Q运转.在泵浦功率为19.1 W时，获得最高平均输出功率为4.58 W，脉冲宽度为84 ns，单脉冲能量为36.6 μJ以及峰值功率为436.2 W的激光脉冲.     

大学物理课程网络辅助教学系统的构建与应用

本文介绍了上海交通大学大学物理课程网络辅助教学系统的设计思想、整体结构和主要的功能模块，概述了运用网络辅助教学系统实施“课堂教学＋网络辅助教学”：这种教学模式的应用情况．     

NiTi合金中马氏体相的低频力学谱研究

我们用最近研制成功的LMA型低频力学谱测试系统对NiTi合金马氏体相进行了在很大频率范围内（0．003～1Hz）的低频等温力学谱和温度谱的测量．我们研究的形状记忆合金NiTi（Ni50．2at％）试样长34mm，直径1mm细丝．经一定热处理，分别在333K．343K和353K做了内耗随频率的变化的测量。实验表明：频率越小，内耗越大，也就是内耗随频率减少而增大。同时我们采用阶梯升温的方法在八个温度下每个温度测量三种频率（1Hz，0．1Hz，0．01Hz）的内耗，结果清楚地表明：不同频率下，内耗峰都出现在372K（99℃）。而且频率越低，峰高越高。这是具有相变峰的特点：相变峰的峰温不随测量频率不同而变化，相变峰高度随频率减少而增大。我们还测量了在1Hz与0．5Hz频率下内耗随温度的变化。本文用马氏体相的位错理论初步讨论了上述实验结果。     

赛跑运动的牛顿力学分析

本文介绍一种用牛顿力学研究赛跑运动的物理模型,给出两种情形下跑步时间的最优化结果.这一结果与优秀运动员的实际比赛成绩很好地相符.     

非负定阵元素的扰动和正定完备化

在保持非负定性不变的前提下,本文对矩阵每一元素容许多大的扰动作了进一步的研究, 将本文的结论和C．R．Johnson提出的部分正定阵的正定完备化进行比较,容易发现对已知的正定矩阵求扰动,本文的结论比用C．R.Johnson的正定完备化计算扰动形式上更简单,同时也给出了不同于C．R．Johnson的部分正定阵的正定完备化表示的另外一个公式,推出了这些正定完备化矩阵应具有的若干性质．