瑞利布里渊光时域分析系统中电光调制器的理论模型与实验研究

瑞利布里渊光时域分析系统能够以非破坏性方式实现单光源、单端工作,利用强度型电光调制器同时调制脉冲基底和脉冲信号是获得该系统所需连续光和脉冲光的关键技术.本文理论分析、仿真和实验研究了一种将脉冲信号输入到电光调制器偏置端、微波信号输入到电光调制器射频端同时调制脉冲基底和脉冲信号的新调制方法,探讨了电光调制器用于瑞利布里渊光时域分析系统时的最佳工作点问题.结果表明,当调制脉冲基底和脉冲时分别将电光调制器偏置在传输曲线的谷点和峰点,并根据实际系统的组成和性能指标要求选择合适的微波调制信号幅度,可获得满足瑞利布里渊光时域分析系统要求的连续光和脉冲光.本文的研究结果为瑞利布里渊光时域分析系统的最佳化设计提供了理论依据.     

铜丝水中电爆炸能量沉积特性

对s脉冲电压作用下铜丝水中电爆炸的能量沉积过程进行了实验研究,利用自积分Rogowski线圈和电阻分压器分别测量铜丝电爆炸时的电流和电压。利用测量电压波形确定了熔融起始、熔融结束、汽化起始和击穿时刻点,将铜丝电爆炸划分成熔融、液态和汽化3个阶段。通过数学方法计算了3个阶段和击穿前的沉积总能量。通过实验和计算,分析了电路参数,包括放电电压和回路电感,以及铜丝特性,包括铜丝长度和直径,对铜丝电爆炸过程中3个阶段和击穿前沉积总能量的影响。结果表明:在s脉冲电压作用下,放电电压、回路电感、铜丝长度和直径对熔融阶段能量沉积影响较小,但对液态和汽化阶段能量沉积影响较大,通过调节电路参数提高电流上升速率,可以显著提高汽化和击穿前的沉积能量。     

一种CCD辅助测量基模(TEM_(00))激光光斑尺寸的方法

激光光束是一种振幅和等相位面都在变化的高斯球面光波 ,其最小光斑的位置和大小不易确定 ,本文在实践的基础上提出一种测量基模 ( TEM0 0 )激光光斑尺寸的方法 ,解决了这一问题     

短焦矩大视场光学系统的畸变校正

本文对短焦矩大视场光学系统的畸变校正进行了讨论,并建立了畸变校正的数学模型,对提高畸变校正精度的途径和技巧进行了探讨和尝试.     

A Donnell type theory for finite deflection of stiffened thin conical shells composed of composite materials

A Donnell type theory is developed for finite deflection of closely stiffened truncatedlaminated composite conical shells under arbitrary loads by using the variational calculusand smeared-stiffener theory.The most general bending-stretching coupling and the effectof eccentricity of stiffeners are considered.The equilibrium equations,boundary conditionsand the equation of compatibility are derived.The new equations.of the mixed-type ofstiffened laminated composite conical shells are obtained in terms of the transversedeflection and stress function.The simplified equations are also given for some commonlyencountered cases.     

复合材料三角形网格加筋圆锥壳体位移型稳定性方程及其总体稳定性分析

本文采用Donnell型扁壳理论,首先利用最小势能原理和广义平均筋条刚度法推导出用位移分量表示的复合材料三角形网格加筋叠层圆锥壳体的稳定性方程,考虑了蒙皮最一般的拉弯与拉扭耦合关系和加筋筋条的偏心效应,并讨论了该方程的基本性质.根据外压实验观察结果,通过选取适当的位移分量表达式,并运用Galerkin法分析了在均布外压作用下复合材料三角形网格加筋叠层圆锥壳体总体稳定性,得到了临界载荷的解析表达式,并对某一类C/E复合材料三角形内网格加筋圆锥壳体的临界外压进行了计算,所得理论值与实验结果很好地吻合.最后,讨论了有关参数对临界载荷的影响.本文所建立的新方程和所得结果对于航空航天结构非常有用.     

河南麦区收割对大气颗粒物及其组分特征排放的影响

农业收割期间排放的颗粒物是农忙期影响大气气溶胶组成的主要来源,因此明确农业收割期间排放的大气颗粒物排放特征具有重要意义。本实验立足河南省新乡市集约化农田实验基地,开展冬小麦区农业收割期间的大气颗粒物及其组分排放特征实验。结果表明收割期间的PMcoarse比其它时期高8.20%,农业站点收割时期的PMcoarse比其它时期高了72.22%,明确了其颗粒物污染特征为仅PM₁₀升高,而非PM₁₀和PM_2.5同时升高,同时PM₁₀的升高非PM_2.5升高引起的;含量最高的前5种元素是Al、Ca、Fe、K、Mg;收割期间,Fe的特征比值最高为0.79;Ca₂₊^和K₊^{离子百分含量在}PMcoarse中占比最高;特征值为0.81和0.78。综合水溶性离子和元素结果,Ca₂₊^、K₊^、Fe浓度协同变化可作为小麦收割过程颗粒物对大气污染影响的指纹识别,以区别于其他污染类型;便于大气污染防治行政主管部门有针对性的查污、防污、治污,提高人民群众生活环境的空气质量。     

Homogeneity analysis of sculptured thin films deposited in symmetric style through glancing angle deposition technique

The symmetric deposition technique is often used to improve the uniformity of sculptured thin film （STF）. In this paper, optical properties of STF with the columnar angles 4-/3 are analyzed theoretically, based on the characteristic matrix method for extraordinary waves. Then, the transmittances of uniformity monolayer and bilayer STF in symmetrical style are calculated to show the effect of the bilayer structure on the optical properties of STF. The inhomogeneity of STF is involved in analyzing the differences in transmittance and phase retardation between monolayer and bilayer STF deposited in symmetric style. The results show that optical homogeneity of STF can be improved by depositing in symmetric style at the normal incidence, but it is not the same case as the oblique incidence.     

Suppression of ion migration in perovskite materials by pulse-voltage method

Hybrid halide perovskites have great potential for applications in optoelectronic devices. However, the typical ion migration in perovskite could lead to the non-repeatability of electrical measurement, instability of material, and degradation of device performance. The basic current-voltage behavior of perovskite materials is intricate due to the mixed electronic-ionic characteristic, which is still poorly understood in these semiconductors. Developing novel measurement schematic is a promising solution to obtain the intrinsic electrical performance without the interference of ion migration. Herein, we explore the pulse-voltage (PV) method on methylammonium lead tribromide single crystals to protect the device from the ion migration. A guideline is summarized through the analysis of measurement history and condition parameters. The influence of the ion migration on current-voltage measurement, such as repeatability and hysteresis loop, is under controlled. An application of the PV method is demonstrated on the activation energy of conductivity. The abruption of activation energy still exists near the phase transition temperature despite the ion migration is excluded by the PV method, introducing new physical insight on the current-voltage behavior of perovskite materials. The guideline on PV method will be beneficial for measuring halide perovskite materials and developing optoelectronic applications with new technique schematic.     

球面壳体上平面光学窗口设计方法

介绍光电系统中球形壳体上光学窗口的设计方法。以红外窗口为例,对常规平面设计方法和UG实体模型方法进行对比。前者采用试凑的方法,后者利用UG实体建模和空间几何转换的方法,得到了光学窗口的正确尺寸和位置,较前者具有直观和理论性强的特点。根据窗口的光学特性和工程实际,确定了窗口的安装固定方式。