一种GPS信号载波跟踪技术

本文提出一种锁相环(PLL)与锁频环(FLL)相级联的 GPS 信号载波跟踪方法， 该方法兼顾了 PLL 的载波跟踪精度与 FLL 的动态适应性，经过验证，该方法可以实现对高动态信号的精确跟踪。     

超越SNOM探针通光孔径尺寸的金属纳米间隙超分辨测量

采用电磁场有限元方法,数值模拟了孔径型扫描近场光学显微镜(aperture Scanning Near-field Optical Microscopy,a-SNOM)在照明模式下的工作过程.针对金偶极天线结构,改变天线长度和纳米间隙尺寸,计算了a-SNOM探针孔径的远场辐射速率随探针端面中心坐标变化的扫描曲线,实现了超越a-SNOM探针通光孔径尺寸的天线金属纳米间隙的超分辨测量,对于100nm通光孔径的探针,可分辨最小尺寸为10nm(0.016倍波长)的金属间隙.通过对比金属和介质偶极天线的a-SNOM探针远场辐射速率测量的计算结果,表明天线金属纳米间隙的超分辨测量的实现是由于金属间隙表面等离激元的激发.     

管式炉中半导体激光器巴条Au80Sn20焊料封装研究

为了提高半导体激光器的封装质量和效率,引入管式炉利用夹具进行批量封装。由于封装质量的好坏直接影响半导体激光器的输出特性和使用寿命,利用MOCVD生长808 nm芯片,重点分析了管式炉温度和封装时间对半导体激光器巴条双面金锡封装质量的影响。利用X射线检测、结电压、光电特性参数和smile效应测试手段,确定了管式炉封装半导体激光器巴条的最优封装条件,为以后的产业化提供了指导意义。     

正则集、单值扩张性和谱映射定理

本文利用正则集和半正则集理论以及单值扩张性理论对32种非空谱的谱映射定理作一梳理.     

Effect of Restricted Geometry on the Structure and Phase Transitions in Potassium Nitrate Nanoparticles

The effect of restricted geometry and thermal prehistory of sample preparation on phase transitions in nanocomposites on base of porous glasses with average pore diameters 7 and 46 nm filled by potassium nitrate have been studied by X-rays and neutron diffraction. The nanoparticle sizes have been determined and phase diagrams (on cooling) for these nanoparticles have been described. It is shown that there is a critical nanoparticle size in the interval from 30 till 20 nm, at which in nanocomposite the ferroelectric phase is realized only regardless of preparation method.     

Application of Graphene as a Sorbent for Simultaneous Preconcentration and Determination of Trace Amounts of Cobalt and Nickel in Environmental Water and Vegetable Samples

A new method using a column packed with graphene as adsorbent was developed for the preconcentration of trace amounts of cobalt (Co) and nickel (Ni) prior to their determinations by flame atomic absorption spectrometry. Several factors influencing the extraction efficiency of Co and Ni and their subsequent determinations, such as pH, amounts of the chelating agent, flow rates of sample and eluent solution, eluent type and its volume, breakthrough volume, and adsorption capacity were established. Under the optimum conditions, the calibration graphs were linear in the range of 4.0‐200.0 μg L^?1 and 5.0‐200.0 μg L^?1 with detection limits of 0.36 μg L^?1 and 0.51 μg L^?1 for Co and Ni, respectively. Good relative standard deviations for ten determinations of 100.0 μg L^?1 of Co and Ni were 3.2 and 3.6%, respectively. The results for determination of Co and Ni in tap water, river water, sea water, vegetable and spiked samples have demonstrated the accuracy and applicability of the proposed method. To validate the proposed method, three certified reference materials of environment water (GSBZ 50030‐94 and GSB 07‐1186‐2000) and tomato leaf (GSBZ 51001‐94) were analyzed, and the determined values were in good agreement with the certified values.     

基于OpenMP的并行空间电磁分布计算

获得空间电磁场场强分布是电磁频谱管理的重要任务之一,研究如何提高其计算性能以适应快速变化的空间电磁环境具有重要的意义。OpenMP(Open Multi Processing)是一种简单快速提高计算效率的方式,它有助于CPU多核资源被充分利用。提出了一种基于Open MP的并行获得空间电磁场场强分布方法,通过合理分析计算过程,设计相应并行方案,使得设计的并行算法适合CPU多核处理方式,并行度高。大量实验结果表明,该并行算法明显提高了计算效率,且具有高可扩展性。     

22 μm波段多波长可调谐光纤激光器研究

设计了一种基于马赫-曾德(M-Z)光纤干涉滤波器的可调谐多波长掺铥环形光纤激光器,M-Z光纤滤波器由两个3 d B耦合器级联构成,通过光纤耦合器接入环形腔中,并利用Sagnac光纤反射镜实现反射式滤波。实验利用一个发射功率为250 m W的1573 nm光纤激光器作为泵浦源,通过一个1570/2000 nm波分复用器(WDM)注入一段4 m长单模掺铥光纤(TDF)中获得2μm波段光增益。环形腔内加入偏振控制器(PC)调节腔内损耗,实现了2μm波段可调谐多波长输出,观测到最多3个波长激光。     

人脸图像信息可用性影响因素的研究分析

传统的图像质量评估技术通常用于判断图像的整体质量,而不能有效地判断人脸图像信息的可用性.而人脸图像信息可用性评估在安防监控中具有很强的应用价值.提出了人脸图像信息可用性的概念,并提出了通过人脸识别算法来评估该可用性的度量方法.通过采用PCA人脸识别算法模拟仿真,定量地从原理上研究了影响人脸图像信息有用性的关键因素,并通过实验进行了验证.