掺杂钾钠铌酸锶钡光折变晶体的各向异性衍射

本文给出了关于光折变晶体各向异性衍射的二波耦合方程,还给出了三种分别掺Cu,Ce,Co的钨青铜结构系列单晶(厚度为0.6—0.8cm)钾钠铌酸锶钡(KNSBN)在He-Ne激光(λ=6328?)照射下产生的光致光栅衍射实验结果。根据二波耦合理论,解释了这三种光析变晶体的衍射图样分布。根据波矢图的分析得出结论:对于不同性(正或负)单轴晶体,只能存在一种各向异性衍射的圆环图样(e→o衍射或o→e衍射)。理论分析与实验基本符合。 关键词：     

原子-辐射场相互作用系统 Heisenberg运动方程的相干态表述

用Heisenberg-Weyle(简称H-W)群直积SU(2)群上的相干态表述了原 子-辐射场相互作用系统的Heisenberg运动方程。引入一个算符振幅函数,将Heisenberg绘 景中算符运动方程转化成可分离变量的偏微分方程,给出了方程的形式解以及时间演化算符 在该表述下的表示。     

北京谱仪III上利用神经网络方法进行粒子鉴别的研究

本文描述了一种多层感知器的神经网络系统在BESIII粒子鉴别技术中的应用。网络按照子探测器分别进行训练, 输出结果可以作为后续网络的输入或者可以为似然函数方法构建概率密度函数。蒙特卡罗模拟样本的检验结果表明, 利用神经网络方法可以在BESIII上获得较好的粒子鉴别效果。     

Photoluminescence Characterization of Silicon Nanoparticles Hybridized Europium Complex

A europium complex Eu (DBM)3 TPPO (Eu tris(benzoylmethide)-(triphenylphosphine oxide)) and silicon nanoparticles have been hybridized.The hybridization can evidently change the photoluminescence (PL) characteristics of the Eu complex in the following aspects:under an excitation of 390nm,the intensity of the PL peak at 611nm due to the ^5Du-^7F2 transition of the Eu^3 ions has been increased by 30%,and thc integrated PL intensity in the visible range has been increased by nearly 3 times;the PL excitation efficiency beyond 440nm has been improved cvidently;the peak in the PL excitation spectrum shifts from 408nm to 388nm,and the PL decay time decreases from 2.07 to 0.96μs,The experimental results indicatde that in the PL process,the photoexcited energy may transfer from the silicon nanoparticlcs to the Eu^3 ions.     

Improved Resistive Switching Characteristics of Ag-Doped ZrO2 Films Fabricated by Sol-Gel Process

Ag-doped and pure ZrO₂ thin films are prepared on Pt/Ti/SiO₂/Si substrates by sol-gel process for resistive random access memory application. The highly reproducible resistive switching is achieved in the 10% Ag-doped ZrO₂ devices. The improved resistive switching behaviour in the Ag doped ZrO₂ devices could be attributed to Ag doping effect on the formation of the stablefilamentary conducting paths. In addition, dual-step reset processes corresponding to three stable resistance states are observed in the 10% Ag doped ZrO₂ devices, which may be implemented for the application of multi-bit storage.     

自旋玻璃的重入行为及CoxZn1-x(FeyCr1-y)2O4尖晶石系统的磁相图

本文研究了Co_xZn_1-x(Fe_yCr_1-x2O₄尖晶石系统的磁性,测量了不同成份样品的低频弱场交流磁化率与低场直流磁化强度的温度关系。根据实验结果,给出了该系统可能的磁相图。发现在该系统中相当宽的成份范围内,都存在自旋玻璃的重入现象。同时发现,自旋玻璃的重入温度随磁性离子浓度增加而增加。这些行为是磁性离子浓度含量较高和多种磁性离子共存系统的共同特性。还讨论了自旋玻璃重入行为 关键词：     

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.     

实验教学与科研创新相结合的探索与实践

大学物理实验课程包括基础型实验、提高型实验、研究型实验等从低到高、从基础到前沿、从传授知识到创新能力培养的完整教学体系,在进行创新人才培养、全面实施创新教育等方面有着其他课程教学不可替代的作用.本文分析了目前大学物理实验课程教学中存在的问题,探索教学与科研创新相结合,更好地培养学生的实践能力、创新能力以及科学研究的思想与方法.     

二维可压缩流体Kelvin-Helmholtz不稳定性

利用高精度数值格式,研究了二维可压缩流体中的Kelvin-Helmholtz不稳定性,主要研究了可压缩性对Kelvin-Helmholtz稳定性增长率的影响.模拟定量的给出低Mach和高Mach数两种情况下,初始静压和对流Mach数以及Kelvin-Helmholtz不稳定性线性增长率的关系.模拟结果和自由剪切层以及混合层的实验结果以及理论分析一致.模拟表明,对流Mach数是描述流体可压缩性的合适参数,对流Mach数越小流体越不可压,Kelvin-Helmholtz不稳定性的线性增长率随对流Mach数的增加而减小. 关键词： Kelvin-Helmholtz不稳定性 可压缩流体 Mach数 超音速流体     

图的倍图与补倍图

计算机科学数据库的关系中遇到了可归为倍图或补倍图的参数和哈密顿圈的问题．对简单图C,如果V（D（G））：V（G）∪V（G′）E（D（G））=E（C）∪E（C″）U{vivj′｜vi∈V（G）,Vj′∈V（G′）且vivj∈E（G））那么,称D（C）是C的倍图,如果V（D（G））=V（C）∪V（G′）,E（D（C））：E（C）∪E（G′）∪{vivj′}vi∈V（G）,vj′∈V（G’）and vivj∈（G））,称D（C）是G的补倍图,这里G′是G的拷贝．本文研究了D（G）和D的色数,边色数,欧拉性,哈密顿性和提出了D（G） 的边色数是D（G）的最大度等公开问题．