电子秤的制作与校准实验

介绍了压力传感器的工作原理,以及用压力传感器制作电子秤并校准的实验过程。     

一种新型高比表面积 TiO2载体在 NH3选择性催化还原反应中对 V2O5分散性的促进作用

A titania support with a large surface area was developed, which has a BET surface area of 380.5 m2/g, four times that of a traditional titania support. The support was ultrasonically impregnated with 5 wt%vanadia. A special heat treatment was used in the calcination to maintain the large sur‐face area and high dispersion of vanadium species. This catalyst was compared to a common V2O5‐TiO2 catalyst with the same vanadia loading prepared by a traditional method. The new cata‐lyst has a surface area of 117.7 m2/g, which was 38%higher than the traditional V2O5‐TiO2 catalyst. The selective catalytic reduction (SCR) performance demonstrated that the new catalyst had a wid‐er temperature window and better N2 selectivity compared to the traditional one. The NO conver‐sion was>80%from 200 to 450 °C. The temperature window was 100 °C wider than the traditional catalyst. Raman spectra indicated that the vanadium species formed more V‐O‐V linkages on the catalyst prepared by the traditional method. The amount of V‐O‐Ti and V=O was larger for the new catalyst. Temperature programmed desorption of NH3, temperature programmed reduction by H2 and X‐ray photoelectron spectroscopy results showed that its redox ability and total acidity were enhanced. The results are helpful for developing a more efficient SCR catalyst for the removal of NOx in flue gases.     

近代物理积件系统

《近代物理积件系统》获’99CIETE全国多媒体教育软件大奖赛一等奖。本文详细介绍了作者主持开发该系统的背景、原则、系统的组成、功能、特点、主要创新点等。     

基于硅基微电子机械系统仿生振膜的光纤麦克风

仿蝇耳声传感器是一种对声压梯度敏感的指向性微型麦克风.本文设计制备了桥连耦合双翼形硅基微电子机械系统仿蝇耳振膜,利用该振膜制作了光纤Fabry-Pérot干涉式麦克风,并对这种麦克风的特性进行了理论与实验研究.仿真结果指出:这种仿生振膜具有摇摆和弯曲两种振动模态,单位声压下摇摆模态的振幅依赖于入射声波的频率与传播方向,频率越接近摇摆模态本征值,振幅越大;摇摆模态振幅随传播方向在三维空间的变化呈纺锤形分布,纺锤的长轴平行于振膜的长轴,意味着传播方向平行于振膜长轴时麦克风灵敏度最高.实验测得的光纤仿生麦克风的摇摆模态本征频率略小于仿真值,其输出信号振幅随声源水平方位角的变化呈“8”字形分布,在0°—60°方位角范围二者呈线性关系,由此得出麦克风的方向灵敏度为39.98 mV/(°).     

两变量随机截距模型的最优设计

本文考虑两变量随机截距模型在单位正方形设计域上的D-,G-,A-,Ds-和I-最优设计.证明了最优设计在设计区域的顶点处获得,得到了几类不依赖于随机截距项的最优设计模拟结果表明最优设计较随机设计可大幅提高参数估计的精确性.     

可用于拓宽光波单向传输带宽的光子晶体异质结构界面

基于光波单向传输的全光二极管在集成光通信、全光网络和光信息处理中有重要应用.基于方向带隙失配设计的光子晶体异质结构可实现光波单向传输,但正向透射率较低,带宽较窄.基于对光子晶体异质界面倾斜角度的研究,根据界面全反射条件,利用可集成材料硅和二氧化硅设计了一种空气孔型二维光子晶体异质结构.异质结构界面两侧的光子晶体对1550 nm波长附近的TE模光波在Γ-X方向均呈导带,避免了方向带隙失配.研究发现当异质界面满足全反射条件时,由于光子晶体的自准直效应,较宽波段的正向光波得以高效传播,而反向光波在界面由于全反射而被禁止传播.光子晶体异质结构界面的全反射效应打破了方向带隙对光波单向传输的限制,使得反向光波在光子晶体中为导带时同样可实现近零透射率,从而拓宽了光波单向传输的波长范围.基于全反射界面的光子晶体异质结构经过优化后,其正向透射率达0.64,透射对比度为0.97,单向传输带宽可达553 nm.     

SVM在物理实验中的应用

SVM是一种新的理论依据充分的机器学习算法．将SVM引入水的黏度测定实验,并将SVM寻求的“最优回归函数”与最小二乘法寻求的“最佳函数”进行了对照,结果发现SVM效果较好,从而说明SVM是一种值得引进的物理实验数据分析方法.     

飞秒激光在铽镓石榴石中的光刻光波导

飞秒激光光刻是一种灵活的三维光子器件制作方法。由于铽镓石榴石具有法拉第效应,具有广泛的应用,利用中心波长为800nm,重复频率为1kHz的飞秒激光,在磁致旋光晶体铽镓石榴石中刻写了双线型和压低圆包层两种光波导,重构了激光诱导折射率改变的分布和测试了光波导的传输损耗。双线型波导具有偏振依赖的导光特性,圆包层波导则不存在偏振依赖的导光特性。对于双线型波导,横电(TE)模和横磁(TM)模相位完全失配,在外加磁场下,导模的偏振面不会发生旋转,光刻的圆包层波导的导模的偏振面能够发生磁致旋转。铽镓石榴石中的双线型和圆包层波导可以作为波导偏振器和磁旋光器件,在集成光学上有潜在的应用价值。     

Energy gap suppression and excess current in Tl_2Ba_2CaCu_2O_8 intrinsic Josephson junctions

Intrinsic Josephson junctions in misaligned Tl2Ba2CaCu2O8 thin film were fabricated on LaAlO3 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.