一维梯度折射率介质光学特性的反演

在单个方波脉冲入射情况下,利用共轭梯度法对一维梯度折射率介质的折射率、吸收系数以及散射系数进行了反演.正问题采用间断有限元法求解,反问题的解则在正问题的基础上通过共轭梯度法得到.研究结果表明,利用单个方波脉冲入射情况下的时域半球反射率以及时域半球透射率作为测试值能够有效地反演一维梯度折射率介质的光学特性及其分布情况.     

用火焰原子吸收光谱法对傣药灯台叶中八种金属元素进行形态分析

照传统煎煮法对中药灯台叶中铜、锌、铁、镁、钙、铬、锰和镉8种元素进行提取;用微孔滤膜分离提取液中的可溶态与悬浮态,利用大孔吸附树脂柱对可溶态中的有机态与无机态进行分离;采用火焰原子吸收光谱法对各种形态中的8种元素进行测定。结果显示,灯台叶中8种元素的总提取率为9.84%～89.07%,浸留比为10.96%～903.4%,悬浮态颗粒吸附率为3.44%～23.37%。该法对各元素的加标回收率为94.5%～111.6%;相对标准偏差在0.29%～2.47%之间,测定结果的精密度和准确度令人满意。     

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对Nb3Sn超导线低温下残余应力进行了分析。通过分析复合材料产生热应力的机理,给出弹性假设下计算残余应变的公式。用有限元分析计算了超导线制造到降温过程中各组分的应力变化情况,得到Nb3Sn超导丝在低温下的残余应变,模拟了不锈钢管对超导线残余应力的影响。     

Mode field converter based on embedded photonic crystal fiber

Six high-index cores are embedded around the central solid core of the photonic crystal fiber to form a fiber embedded photonic crystal fiber （FEPCF）, which is investigated based on the beam propagation method. In this structure, the Gaussian mode could be transferred to the ring mode. So FEPCF could used as a mode convertor.     

万变不离其宗——看两道高考题所折射出的新课程理念

杨氏双缝干涉实验是高考物理的重要考查实验之一,在每年全国各省市的试题中均有体现．但是绝大多数学生在学习该知识时只是机械地记住相邻两条亮纹（或暗纹）间的距离公式,而对产生干涉现象的原理和条件不甚了解．2008年四川卷中的“双棱镜干涉”和2005年江苏卷中的“洛埃镜实验”正是以“杨氏双缝干涉实验”为依据,     

Evolution of Quantum Phase Space Distribution: a Trajectory-Density Approach

The trajectory-density method operators. We propose a new of a quantum system is developed by scheme of approximation from two using local Koopman and Frobenius-Perron sets of trajectory-density mixed equations. By examining the local generation and termination of trajectories, we show how they can be adopted to the propagation of negative values of the Wigner function even if it starts off positive everywhere.     

Investigation on Guided-Mode Characteristics of Hollow-Core Photonic Crystal Fibre at Near-Infrared Wavelengths

Guided-mode characteristics of hollow-core photonic crystal fibre （HC-PCF） are experimentally and theoretically investigated. The transmission spectrum in the range from 755 to 845nm is observed and the loss is measured to be 0.12dB/m at 800nm by cut-back method. Based on the full-vector beam propagation method and the full-vector plane-wave method, the characteristics of mode field over propagation distance 1 m are simulated, and the results show that the propagation efficiency can be above 80%. Compared with the fundamental guided mode well confined in air core within shorter propagation distance, the second-order guided mode leaks into the cladding region and gradually attenuates due to larger refractive index difference. The primary loss factors in HC-PCF and the corresponding solutions are elementarily discussed.     

Effect of Different Substrate Temperature on Phosphorus-Doped ZnO Thin Films Prepared by PLD on Sapphire Substrates

Phosphorus-doped ZnO （ZnO：P） thin films are deposited on a c-plane sapphire in oxygen at 350℃, 450℃, 550℃ and 650℃, respectively, by pulsed laser deposition （PLD）, then all the ZnO：P samples are annealed at 650℃ in oxygen with a pressure of 1 × 10^5 Pa. X-ray diffraction measurements indicate that the crystalline quality of the ZnO：P thin films is improved with the increasing substrate temperature from 350℃ to 550℃. With a further increase of the deposition temperature, the crystalline quality of the ZnO：P sample is degraded. The measurements of low-temperature photoluminescence spectra demonstrate that the samples deposited at the substrate temperatures of 350℃ and 450℃ show a strong acceptor-bound exciton （A^0X） emission. The electrical properties of ZnO：P films strongly depend on the deposition temperature. The ZnO：P samples deposited at 350℃ and 450℃ exhibit p-type conductivity. The p-type ZnO：P film deposited at 450℃ shows a resistivity of 1.846Ω·cm and a relatively high hole concentration of 5.100 × 10^17 cm^-3 at room temperature.     

不同提取方法对菟丝子总黄酮和金属元素锌的含量比较研究

分别采用常规回流提取法、石油醚脱脂-索氏提取法和微波辅助萃取法对中药菟丝子进行提取;以芦丁为对照品,紫外分光光度法测定提取物中总黄酮的含量;原子吸收光谱法测定提取液中金属元素锌的含量,以总黄酮的含量和金属元素锌的含量为考察指标,明确金属元素锌的提取与黄酮类总含量之间的关系。结果表明,3种提取方法中,微波辅助萃取法具有高效、省时等优点,提取效果最好,锌元素的含量与总黄酮的含量成正比。     

三棱镜的全反射特性研究

1 引言 文献[1]讨论了三棱镜偏向角与入射角的关系,用最小偏向角法来测量玻璃的折射率,称为三棱镜的折射特性.在实验中,如果入射光线的入射角小于"最小入射角"时,偏向角不存在,即没有出射光线,而出射光线实际上在第二个折射面上产生了全反射,称为三棱镜的全反射特性.