Coupled-Channel Optical Calculations for e＋-Rb Collision at Intermediate Energies

We present the calculation of total cross sections for positron scattering by Rb at intermediate energies by using the coupled-channel optical method, in which an equivalent-local optical potential has been used to describe the continuum and rearrangement process. The present total cross sections are in good agreement with the measurements of Parikh et al. [Phys. Rev. A 47 （1993） 1535] and other theoretical calculation results. Our results show three peaks in the vicinity of 47eV, which have not been found in the previous measurements and theoretical calculations.     

CO2激光和等离子体清洗提高石英基片损伤阈值

 采用连续CO₂激光和真空等离子体相结合的方法对石英基片进行清洗。通过光学显微图、水接触角、透过率和损伤阈值测量分别表征了CO₂激光和等离子体对真空硅脂蒸发物污染过的石英基片的清洗效果。研究表明：对于真空硅脂蒸发物污染后的石英基片，可以先采用低能量的CO₂激光进行大面积清洗，再用真空等离子体进行精细清洗。光学显微图像表明：清洗后的基片表面的油珠被清除干净；水滴接触角由63°下降到4°；在400 nm附近，基片透过率由92.3%上升到93.3%；损伤阈值由3.77 J/cm²上升到5.09 J/cm²。     

绕流等边三角形排列的三圆柱

本文研究了绕流等边三角形排列三圆柱的气动力及其相互干扰。针对某一特定的中心距(1.75d,d为圆柱直径),进行了压力分布的测量和气动力的推算。结果表明,在这种间距下干扰是严重的,除阻力之外,还产生了相当大的横向力,而且随着风向的改变,这种横向力可能是相斥的,也可能是相吸的。另外,圆柱的局部表面有极强的负压力系数。     

改革数学作业的初步尝试

数学作业是数学教学的重要一环,是学生通过自己的实践活动巩固已掌握的基础知识和基本技能,逐步形成能力的必要途径;也是教师了解学生学习情况和检查教学效果的一个有力手段。为使数学作业紧密配合课堂教学,在不断提高学生的能力方面起到更大的作用。     

正定几何规划的相关退化问题

n_k-1,k=0,1,…,r-1;n_r=n,n为所有 f_k(t)(k=0,1,…,r)包含的总项数,n_k-m_k 1为f_k(t)包含的项数. 它的目标函数取对数形式的对偶规划D:     

放射性绝对测量和半衰期(Ⅱ)介绍一个非经典的获取衰变常数或半衰期的方法

本文介绍了一个非经典的获取放射性核素^99mTc的衰变常数及半衰期的方法并与经典的最小二乘法分析结果进行比较。非经典法的结果是T_1/2=6.006±0.004小时,经典法的结果是T_1,2=6.009±0.005小时。     

A HYPOTHESIS OF DNA STRUCTURE——INSPIRATION FROM THE TOPOLOGICAL TRANS-FORMATION OF SUPERCOILED DNA

The tertiary structure of supercoiled DNA will be changed if it reacts with glyoxal undercertain conditions. By the reversible reaction of glyoxal with DNA, we have observed topo-logical transformations among different forms of supercoiled DNA. It is difficult to account for the electrophoretic behavior and the electronmicroscopicpattern of the reaction product by the Watson-Crick double helix model. We would like tosuggest a hypothesis concerning the tertiary structure of DNA which seems to be moreapplicable to the explanation of various facts and related phenomena.     

SOME PHENOMENA FOR WEAK SPRING DUFFING EQUATION IN SUBHARMONIC AND ULTRASUBHARMONIC REGION

In this paper the situation in which weak spring Duffing equation gets into the chaos onaccount of small perturbation is discussed with Melnikov-Holmes′method,and somephenomena in which the different subharmonic and the ultrasubharmonic coexist with thechaos are discovered.     

A new differential absorption lidar for NO_2 measurements using Raman-shifted technique

Based on Raman-shifted wavelengths of D2 and CH4 pumped by third harmonic of Nd:YAG laser, a differential absorption lidar was presented in this paper and had been constructed for probing environmental NO2 concentration. NO2 experimental measurements were carried out at Anhui Institute of Optics and Fine Mechanics in Hefei. Some NO2 measurement results were given and discussed.     

低压荧光粉 ZnS ：Ag/ ZnO

引言 低压阴极射线荧光粉过去广泛使用的只有发蓝绿色光的ZnO∶Zn一种。近几年来,为使低压荧光粉品种及其发光颜色多样化,主要开展两个方面的工作:一是研究新的单一型的荧光粉,例如ZnGa_2O_4∶Mn和SnO_2∶RE(RE:稀土离子);二是将现有的彩色电视荧光粉改变成低压荧光粉。 Aбаллуев,B.B.指出,低压荧光粉必须具有良好的导电性,高压荧光粉在低压电子束激发下不能发光的主要原因是电阻率很高所致。因此,阀值电压较高的高压荧光粉要使在低压下发光,必须改善阳极粉层的导电性。