空间距离的统一向量公式及应用

立体几何中的空间距离(指点线距离,点面距离,线面距离,异面直线距离及平行平面距离;下同)是用数量刻划点、线、面的空间位置关系,也是空间垂直关系的运用和拓展,在立体几何中有着重要的地位.由于空间距离涉及到诸多的线与线,线与面、面与面的垂直关系,求空间距离成为了学习几何的难点.笔者在教学实践中,体会到用向量恰好能避免这一难点,归纳出空间距离的统一向量公式:d=|n0·p|=|n·p||n|,其中p为两个图形任意两点的连线向量,n0为平面(或直线)单位法向量,n为平面(或直线)法向量.1证明下面分四种情况说明.(Ⅰ)点到直线距离:如图1,n为l的法向…     

数学串诗一首

忧愁是可微的，快乐是可积的，在趋向于正无穷的日子里，幸福是连续的，对你祝福可导且大于零，祝你生命里快乐和幸福的复合函数总是最大值!     

高电荷态氪离子双电子复合过程的理论研究

本文采用相对论的Flexible Atomic Code (FAC) 程序计算类氦Kr34+离子双电子复合的截面及速率系数,其中用n-3标度律对速率系数作了外推.文中我们还讨论了辐射分支比随不同共振峰的变化以及级联辐射的影响.     

Au^52＋离子的双电子复合速率系数

利用基于相对论组态混合的扭曲波近似方法计算了从类钴金离子的基态3s^23p^63d^9（J=5／2）经过类镍的3l^17nl＂和3l^164l’nl＂电子组态的双电子复合速率系数，并考虑了级联辐射到可自电离能级退激的影响，给出了包含级联辐射在内的能级到能级的外推方法．     

一堂高中数学新课程“样本课”引发的思考

1课例涉及的焦点问题教材的变化是新一轮课程改革的一个缩影,体现了当前课程改革的基本理念.在新课程实施伊始阶段,大家都在“摸着石头过河”,对教材的内容处理、要求把握、教学方式及新课标理念的体现等方面都遇到了困惑.当新教材呈现在教师面前时,我们面临的问题是理解课标要求,思考教材编写的意图,研究新教材“新”在哪里?“改”在何处?“教”的如何?更需要从操作层面把握课程改革中原有内容要求和处理方式的变化,对内容变化的合理性和操作性作相应的思考.聚焦课堂,通过听课、评课和课例分析等教研活动无疑是有效的手段.为了交流新课程实…     

电子离子碰撞过程中的共振激发双自电离

利用相对论修正扭曲波玻恩近似, 计算了类钠离子Ti11+ 和Cr13+ 的电子碰撞直接电离, 激发自电离和共振激发双自电离截面. 理论数据与实验结果在整个能区内很好符合. 共振激发双自电离截面对总截面的贡献约为20%-30%, 对速率系数的影响较大, 不可忽略.     

Dielectronic recombination of Co-like tantalum

Ab initio calculation of the total dielectronic recombination (DR) rate coefficient from the ground state of Co-like tantalum is performed using the relativistic distorted-wave approximation with configuration interaction. The contributions to the total DR rate coefficients are explicitly calculated from the complexes of Ni-like tantalum: 3s²3p⁶3d_3/2³ 3d_5/2⁶ n'l', 3s²3p⁵3d¹⁰n'l', 3s3p⁶3d¹⁰n'l', 3s²3p⁶3d⁸4ln'l', 3s²3p⁵3d⁹4ln'l' and 3s3p⁶3d⁹4ln'l' with n' ≤ 25, and 3s²3p⁶3d⁸5ln'l' with n' ≤ 9. The l' and n' dependences of partial DR rate coefficients are investigated. The contributions from higher n'complexes are evaluated by a level-by-level extrapolation method. The total DR rate coefficients mainly come from the complex series 3s²3p⁶3d⁸4ln'l', 3s²3p⁵3d⁹4ln'l' and are fitted to an empirical formula with high accuracy. Comparison of the present results with those of other works shows that the previously published data underestimate significantly the DR rates of Co-like tantalum.     

Temperature-Dependent Far-Infrared Absorption in Cyclotrimethylene Trinitramine Single Crystals Using Broadband Time-Domain Terahertz Spectroscopy

We investigate the absorption properties of cyclotrimethylene trinitramine(RDX) single crystals from ～15 to150 cm-1 using the terahertz time-domain spectroscopy. We observe that all the absorption modes exhibit strong anisotropic behavior in terms of the crystal orientations. We demonstrate that the anharmonic phonon model can well describe the temperature-dependent behaviors of these absorption modes. These results indicate that the intermolecular interaction plays a major role in the collectiv...     

Investigations of the dielectronic recombination of phosphorus-like tin at CSRm

The electron–ion recombination for phosphorus-like~(112) Sn~(35+)has been measured at the main cooler storage ring of the Heavy Ion Research Facility in Lanzhou, China, employing an electron–ion merged-beams technique. The absolute total recombination rate coefficients for electron–ion collision energies from 0 e V–14 e V are presented. Theoretical calculations of recombination rate coefficients were performed using the Flexible Atomic Code to compare with the experimental results. The contributions of dielectronic recombination and trielectronic recombination on the experimental rate coefficients have been identified with the help of the theoretical calculation. The present results show that the trielectronic recombination has a substantial contribution to the measured electron–ion recombination spectrum of~(112)Sn~(35+). Although a reasonable agreement is found between the experimental and theoretical results the precise calculation of the electron–ion recombination rate coefficients for M-shell ions is still challengeable for the current theory.     

类氦离子在辐射复合中的光子角分布和极化

本文在偶极近似下,采用准相对论扭曲波近似方法系统得计算了10种类氦离子辐射复合到2P子壳层中发射光子的各向异性因子、角分布和极化,给出了各向异性因子的经验公式.