Novel method for synthesis of titanium silicalite-1 (TS-1)

Titanium silicalite-1 (TS-1) was easily synthesized using inorganic silicon and titanium source, tetrapropylammonium bromide (TPABr) or TPAOH as templating molecule, NH3· H2O, HDA or TEAOH etc. as base sources. In this system, TPA cations (come from TPABr or TPAOH) served as tern-plating agents to direct the MFI structure. NH3H2O, TEAOH or HDA etc. provides the alkalinity necessary for crystallization. X-ray diffraction, UV-Vis, ER spectroscopies, SEM, 29 Si MAS NMR showed that the zeolites obtained possessed all the structural characteristics of TS-1, and titanium atoms were introduced into the framework in TS-1. This material was proved to have high crystallinity and high catalytic activity to allyl chloride epoxidation and propylene epoxidation. All the samples synthesized had similar catalytic properties with a standard TS-1 through compared inorganic reactant system with organic synthesis system using propylene epoxidation. The effects of silicon source and TPABr/SiO2 ratio were discussed.     

多元文化下的勾股定理——数学文化研究性学习教学案例

数学中有个神秘的它,商高量地靠它,陈子测日凭它,古埃及人论它,巴比伦人谈它,毕达哥拉斯眼中的方砖地板中藏它.此刻,我们心中的它:脱俗外貌神秘,荡漾智能活力.人类文明使者,发迹古国异地.(此为序言,教师在古典轻音乐声中道白,从而承上启下,展示课题:多元文化下的勾股定理.其教学全程在教师的主导下,借助投影屏幕把学生带入一个灿烂的数学文化园地.)     

输出反馈重极点配置问题的理论与算法

本文主要讨论具有给定特征结构的输出反馈重极点配置问题.§1为重极点配置问题的提出.§2讨论解存在的理论.附录给出§2中两个主要定理的证明。     

Photoluminescence study on Eu-implanted GaN

The photoluminescence (PL) properties of Eu-implanted GaN thin films are studied. The experimental results show that the PL intensity is seriously affected by ion implantation conditions. The PL efficiency increases exponentially with annealing temperature increasing up to a maximum temperature of 1050℃. Moreover, the PL intensity for the sample implanted along the channelling direction is nearly twice more than that observed from the sample implanted along the random direction. The thermal quenching of PL intensity from 10K to 300K for sample annealed at 1050℃ is only 42.7%.     

单模光纤弯曲损耗的测量与分析

从理论和实验两方面讨论了弯曲半径及工作波长对单模光纤弯曲损耗的影响，测量了1310nm和1550nm波长光作用下，弯曲损耗随弯曲半径的变化关系。结果表明：随着弯曲半径的增大，弯曲损耗系数呈下降趋势，并且伴有振荡现象出现；而且，在弯曲半径较大时，弯曲损耗变化平缓，1550nm波长较1310nm波长明显更易产生弯曲损耗，而小弯曲半径对应的弯曲损耗振荡剧烈，此时两种光波长对弯曲损耗的敏感程度交替变大。     

Analysis of random laser scattering pulse signals with lognormal distribution

The statistical distribution of natural phenomena is of great significance in studying the laws of nature. In order to study the statistical characteristics of a random pulse signal, a random process model is proposed theoretically for better studying of the random law of measured results. Moreover, a simple random pulse signal generation and testing system is designed for studying the counting distributions of three typical objects including particles suspended in the air, standard particles, and background noise. Both normal and lognormal distribution fittings are used for analyzing the experimental results and testified by chi-square distribution fit test and correlation coefficient for comparison. In addition, the statistical laws of three typical objects and the relations between them are discussed in detail. The relation is also the non-integral dimension fractal relation of statistical distributions of different random laser scattering pulse signal groups.     

柱形长杆弹侵彻的界面击溃分析

在Alekseevski-Tate模型的基础上,分析了柱形长杆弹的界面击溃过程,给出了弹体速度下降及质 量侵蚀的计算公式;讨论了弹体速度下降及质量侵蚀对动能损失的影响;特别针对柱形长杆弹在界面击溃过 程中弹体速度准定常小量变化的特点,近似给出了弹体速度、弹体质量随时间变化的简化解析表达式,为工程 应用提供便利。