近地面折射率结构常数的长期测量和统计分析

统计分析了1997～2000年合肥地区一复杂地形处近地面折射率结构常数的测量数据。给出了不同下垫面、不同季节、不同高度上的统计结果。白天强弱依次为6月、5月、4月、9月、1月。白天水面上比草地上小,夜间比草地上大。不论白天还是夜晚,近地面结构常数都随高度递减,且3～10m高的结构常数递减较慢,10～15m高的结构常数递减较快。结构常数随月份的日变化与模式计算结果基本一致。     

同轴线方法测量束流耦合阻抗的有效性分析

根据同轴线方法测量阻抗的原理,用模拟方法讨论了该测量方法的有效性问题。从均匀圆波导和同轴线结构中的电磁场解析分析,说明了该方法有效性问题的起源和基本物理图像,简单回顾其他方法讨论该问题的结论,最后数值模拟分析了同轴线方法测量束流耦合阻抗的有效性,所得主要结论能够对阻抗测量平台的设计提供可靠的依据。     

等离子体电极电光开关特性参数测量

建造一套电光开关参数测量系统,具备时间分辨、空间分辨及全口径平均测量能力。介绍了240mm×240mm等离子体电极普克尔盒电光开关特性参数及测量光路,并给出了实验测量结果。     

Synthesis and Characterization of 2d Ferromagnetic (RNH3)2CrX4 Containing Mixed-Halides,R = CnH2n+1, X = Br,C1

The bis(benzylammonium)tetrahalogenochromate(II), (C₆H₅CH₂NH₃)₂CrBr₃. ₃Cl₀. 7, has been synthesized and characterized. The crystal structure is related to that of K₂NiF₄. The compound is ferromagnetic and the Curie temperature T_C (T_C= 49 K) has been measured by a mutual inductance technique. The susceptibility increases sharply at T_C and then shows a drop-off below T_C, typical of a single-domain powder sample. The compound is found to behave as a typical 2D easy plane ferromagnet.     

Orientational order parameter determination of the liquid crystal: 4 propyl paraethoxy phenyl cyclohexyl carboxylate by X-ray studies

The compound 4 propyl paraethoxy phenyl cyclohexyl carboxylate (code name D302) is a member of a homologous series and exhibits liquid crystalline (nematic) behavior in the temperature range 48°C to 78°C. An experiment has been set up for conducting X-ray studies of liquid crystal samples at various temperatures. From X-ray studies conducted at different temperatures on D302, the apparent molecular length and inter-molecular distance and their temperature dependence have been determined. The variation of the orientational-order parameter <P₂>_xray has been determined from the intensities of the scanned X-ray photographs taken at different temperatures. The results have been compared with the<P₂>_opt values obtained by us from birefringence studies.     

DYNAMICAL CONTROL OF STABILITY FOR BIRKHOFFIAN SYSTEM$^{\bf 1)}$

本文研究 Birkhoff 系统和广义 Birkhoff 系统平衡稳定性的动力学控制. 首先建立系统的运动方程和平衡方程. 其次,研究 Birkhoff 系统中控制参数出现在 Birkhoff 函数中平衡稳 定性的动力学控制. 方法是通过选取控制参数使得 Birkhoff 函数 $B$ 成为定号函数,而其时间导数 $\dot {B}$ 为与 $B$ 反号的常号函数. 再次,研究广义 Birkhoff 系统平衡稳定性的动力学控制,通过选取 Birkhoff 函数或附加项中包含控制参数的方法,使得 Birkhoff 函数是定号函数,而其时间导数为反号的常号函数,从而控制系统的平衡稳定性. 最后举例说明结果的应用.     

A closed form of a kurtosis parameter of a hypergeometric-Gaussian type-Ⅱ beam

Based on the irradiance moment definition and the analytical expression of waveform propagation for hypergeometricGaussian type-Ⅱ beams passing through an ABCD system, the kurtosis parameter is derived analytically and illustrated numerically. The kurtosis parameters of the Gaussian beam, modified Bessel modulated Gaussian beam with quadrature radial and elegant Laguerre–Gaussian beams are obtained by treating them as special cases of the present treatment. The obtained results show that the kurtosis parameter depends on the change of the beam order m and the hollowness parameter p, such as its decrease with increasing m and increase with increasing p.     

会聚厄米-双曲余弦高斯光束的光强分布和焦移

 基于厄米-双曲余弦高斯光束通过无光阑限制薄透镜聚焦的解析传输公式，研究了厄米-双曲余弦高斯光束聚焦区域的光强分布，并对光束的焦移进行了分析，讨论了偏心参数对光强主极大位置的影响。结果表明：TEM₁₁模厄米-双曲余弦高斯光束的相对焦移（绝对值）随偏心参数和菲涅尔数的减小而增大，菲涅尔数较大时相对焦移趋于零。TEM₂₂模光束在偏心参数小于0.54时，轴外与轴上光强极大值的比值大于1，此时光强主极大在轴外，偏心参数大于0.54时则相反；在偏心参数等于0.54时比值为1，此时光束有两个主极大，偏心参数愈大光强愈集中于轴上。使用LW法和GH法得到的TEM₂₂模光束的相对焦移（绝对值）随偏心参数和菲涅尔数的变化规律与TEM₁₁模光束一致，但相同参数下使用这两种方法得出的具体结果不同。     

The Hubble diagram of metal-rich QSOs and deceleration parameter q0

For 163 metal-rich Quasars, the m_v-logZ diagram shows a very close correlation. Using multiple regression analysis for these sources (N = 163), we obtained q₀,= 1.142 and correlation coefficient γ = 0.69. These results suggested that the Universe is closed and all metal-rich quasars are of a single category. On the other hand, the evolution is very small at Z⩽2 for metal-rich quasars.