新型轨道交通信号点灯系统浅析

从我国铁路信号点灯装置现状着手,说明了一种新型信号点灯系统的关键性技术和解决的技术难题,其中包括:四档开关返馈修正高精度稳压电路、双丝灯泡点灯和LED点灯二者兼容、LED脉冲点灯技术、LED灯电流及光度双监测、付丝在线实时监测转换电路、插拔式安装、原报警电缆报警、防雷变压器等技术特点。通过对比研究,表明该新型系统具有突出的优点。最后分析了该系统的需求状况,表明它具有良好的市场前景。     

流体力学基本方程组(BEFM)的层次结构理论和简化Navier-Stokes方程组(SNSE)

本文从流场中空间和时间的尺度分析及流体力学基本方程组(BEFM)中诸项的量级分析出发,提出了BEFM的层次结构理论,表明:当特征雷诺数Re>l、且一坐标方向的长度尺度大于其它坐标方向的长度尺度吋,按照BEFM中诸项的量级关系,形成从Euler方程到 BEFM 和从边界层方程到 BEFM 的两支层次结构,文中以二维可压缩流动和不可压缩轴对称射流为例说明了两支层次结构的关系和特点,分析了诸层次方程组的特征、次特征(Subcharacteristics)以及它们的数学性质,并把诸层次方程组与已有的诸简化Navier-Stakes方程组(SNSE)作了对照比较。     

三峡库区巴东组地层的发育特征及其空间变化规律

根据大量的野外实际观察、室内岩石标本的薄片鉴定及化学成分分析结果,作者详细论述了三峡库区巴东组地层(T2b)的发育特征及其空间变化的规律性。巴东组地层在秭归、巴东、巫山、奉节等4个地区的总厚度最小约为830m,最大约为1420m,自东而西地层总厚度具有逐渐增大的趋势。红色与灰色是巴东组地层的两大基本色调,红色系列的岩层(第二、四段),多见为碎屑或砂泥质岩类,而灰色系列的岩层(第一、三、五段),多见为碳酸盐岩类。由其发育特征可知,巴东组为典型的易滑岩组。     

啁啾脉冲堆积宽带激光的时间与频谱特性分析

理论研究了啁啾堆积脉冲宽带激光时间与频谱特性与子脉冲参量的关系.结果表明,变换极限子脉冲堆积所得的脉冲平滑,频率啁啾型与时间啁啾型子脉冲堆积所得脉冲出现时间调制,平滑性变差,从频谱上看,前者出现单一谱线,而后者可看到多条谱线|随着子脉冲间延迟的增加,堆积脉冲由脉冲间干涉引起的时间调制增多,但幅度减弱,而频谱的谱线数量增加.所得结果可为适当地选择堆积脉冲参量以获得所需的时间与频谱形状的宽带激光提供参考.     

MEMS变形反射镜主要特性测试

介绍了基于微机电系统技术的微变形反射镜的基本结构和电极分布.分析了微机系统变形镜的变形原理,推导了微变形镜的镜面变形与外加驱动电压的关系.分析了基于计算机控制的频闪显微干涉测量系统的组成及测试原理,并利用该系统实现了对微变形镜静态电压-位移曲线、静态面形、动态离面变形以及谐振频率的测试.实验表明,测试结果与理论分析有很好的一致性.     

ADSORPTION OF UO2 2+ BY POLYETHYLENE HOLLOW FIBER MEMBRANE WITH AMIDOXIME GROUP

The polyethylene (PE) membrane was prepared by the radiation-induced grafting of acrylonitrile (AN) onto PE hollow fiber and by the subsequent amidoximation of cyano groups in poly-AN graft chains. The adsorption characteristics of the chelating hollow fiber membrane was examined as the solution of UO₂ ²⁺ permeated across the chelating hollow fiber membrane. The inner and outer diameter increased with an increasing grafting yield, whereas, the pure water flux and pore diameter decreased with an increasing grafting yield. The adsorption of UO₂ ²⁺ by the chelating hollow fiber membranes increased with an increasing amidoxime group. The adsorbed amount of UO₂ ²⁺ in the uranyl acetate solution was higher than that in the uranyl nitrate solution. The adsorbed amount of UO₂ ²⁺ is higher than that of Cu²⁺ when the solution of UO₂ ²⁺ and Cu²⁺ permeated across the chelating membrane, respectively. The adsorption characteristics of UO₂ ²⁺ by the amidoxime group-chelating fiber membrane in the presence of Na¹⁺ and Ca²⁺ showed a high selectivity for UO₂ ²⁺ even though there was a high concen-tration of Na¹⁺ and Ca²⁺ in the inlet solution.     

Investigation of use of reach-back characteristics method for 2D dispersion equation

The use of the Holly-Preissmann two-point scheme has been very popular for the calculation of the dispersion equation. The key to this scheme is to use the characteristics method incorporating the Hermite cubic interpolation technique to approximate the trajectory foot of the characteristics. This method can avoid the excessive numerical damping and oscillation associated with most finite difference schemes for advection computation. On the basis of the fundamental idea of the Holly-Preissmann two-point scheme, a new technique is introduced herein for the computation of the two-dimensional dispersion equation. This new scheme allows the characteristics projecting back several time steps to fall on the spatial or temporal axis, while the characteristics foot is still solved by the Holly-Preissmann two-point method. The diffusion portion of the dispersion equation is solved by the commonly used Crank-Nicholson method. The calculation for these two processes consisting of advection and diffusion is carried out separately but consecutively in one time step, a method known as the split operator algorithm. A hypothetical model was constructed to demonstrate the applicability of this new technique for the calculation of the pure advection and dispersion equation in two dimensions.     

聚烯烃合金的研究进展(Ⅱ)——分级方法、结构调控与性能

聚烯烃合金是通过釜内聚合制备的多组成的聚烯烃材料。本文分别从聚烯烃合金的分级方法、组分和性能等方面对聚烯烃合金结构与性能进行了评述,重点介绍了溶剂抽提分级法、温度梯度分级法、升温淋洗分级法、等温热分级法和逐步结晶分级法等聚烯烃合金分级方法的原理,特别关注了聚丙烯/橡胶弹性体合金、聚丙烯/聚乙烯合金及聚丙烯/聚丁烯合金的组成与性能。并分析了聚烯烃合金的发展趋势。     

飞机交流电源特性参数测量研究

飞机机载电源系统供电品质直接关系到飞机用电设备可靠工作和飞行安全,为此,2006年国际标准组织推出了新的机载电源标准ISO1540-2006;本文根据该标准要求,提出了一种机载电源的稳态和瞬态特性的测试的实用方法;建立了测量的数学模型;采用虚拟仪器技术,设计硬件测试平台,包括功率因数可调的大功率数字化程控负载和计算机数据采集系统;基于LabVIEW开发了测试软件;为满足暂态特性的测量要求和精度要求,采用了NI高速高精度数据采集卡,实现了较高的测量精度,综合测量误差小于0.5%,并在暂态测量中,考虑了负载接触器吸合时间;该测试系统可以用来检验恒频机载交流电源的特性是否符合国际标准要求,以保证飞行安全。     

ICP-AES用于金莲花的无机元素初级形态分析及其溶出特征性研究

采用传统花茶饮用方法对金莲花茶中的Fe、Mg、Cu、Zn、Mn、Cr、Pb、As 8种元素进行浸取;按照初级形态分析流程制备样品溶液,用0.45μm微孔滤膜分离浸取液中的可溶态和悬浮态。应用电感耦合等离子体-原子发射光谱法（ICP-AES）对此花茶中8种无机元素的初级形态进行测定。结果显示：金莲花茶中8种元素的浸出率在17.2%—72.3%之间,可溶态在水浸液中的比率在67.4%—98.6%之间。