双包层稀土掺杂光纤抽运吸收特性的分析

建立了复折射率纤芯结合有限差分束传播法的双包 层稀土掺杂光纤抽运吸收效率数值模型,利用该模型对几种常 用内包层外边界结构下双包层稀土掺杂光纤的抽运吸收系数进 行了详细的分析,得出相应双包层光纤的抽运吸收特性. 分析结果对双包层稀土掺杂光纤的优化设计具有重要的指导意义.     

脉冲相干激光雷达测距信号研究

对脉冲激光雷达外差测距信号进行了研究，理论上，采用调Q激光脉冲的数值计算波形，研究了脉冲激光经远处目标漫反向后进行外差接收的波形及其傅里叶变换频谱成分。实验上，研究了可调谐电光调Q射频激励波导CO2激光器脉冲激光经目标反射后的外差波形及其傅里叶变换频谱成分，并计算了目标的距离，理论分析与实验结果一致。     

用分光计测定普朗克常数及微机的数据处理

用分光计测定普朗克常数及微机的数据处理①何红雨李琦（右江民族师专百色５３３０００）（桂林医学院桂林５４１００１）在普通物理实验中，通常是用光电效应来测定普朗克常数的，但结果并不理想，误差较大。既然实验的目的是测定普朗克常数的值，我们则采用氢灯作为光源...     

数学建模与数学建模教学中的若干问题

数学建模与数学建模教学中的若干问题李琦（北方交通大学）序数学建模教育近十几年来在国际上引起了广泛的重视，在一些发达国家的高等院校中不仅为本科生和研究生开设了数学模型课程，而且还举办相应的数学建模竞赛。国内的一些全国重点院校也先后开设了数学模型课程，并...     

信息科学中的优化问题──数学建模教学插件

信息科学中的优化问题──数学建模教学插件李琦（北方交通大学）１．引言《数学模型》目前还是一门很不成熟的课程，无论是教材还是教法都需要做更深入的探讨和研究。数学建模教学插件是数学模型课程教材的一个重要组成部分，是数学模型课程教学的重要基础建设。一个好的...     

New SOI power device with multi-region high-concentration fixed interface charge and the model of breakdown voltage

A new SOI power device with multi-region high-concentration fixed charge(MHFC) is reported. The MHFC is formed through implanting Cs or I ion into the buried oxide layer(BOX), by which the high-concentration dynamic electrons and holes are induced at the top and bottom interfaces of BOX. The inversion holes can enhance the vertical electric field and raise the breakdown voltage since the drain bias is mainly generated from the BOX. A model of breakdown voltage is developed, from which the optimal spacing has also been obtained. The numerical results indicate that the breakdown voltage of device proposed is increased by 287% in comparison to that of conventional LDMOS.     

基于地质分类进行水驱开发效果评价

根据杏南油田不同开发阶段的动静态资料,详细研究工区的油藏地质特征,明确影响开发的地质因素,并在此基础上进行了生产动态分析及开发效果评价.针对模糊综合评判法在权重确定方面的随意性,提出了一种基于客观赋权的模糊综合评判方法,建立了一种新的基于地质分类的水驱开发效果评价方法.评价结果符合区块地质实际概况,能够较准确地、定量评价水驱开发效果.根据评价结果对区块进行措施调整,取得了明显的社会和经济效益.     

激光雷达地面目标姿态估计

激光雷达距离像能表征目标的几何结构,而同一目标不同姿态的距离图像差别较大,因此目标姿态的准确估计对目标识别尤为重要。Ulf Grenander的模式理论利用变形模板表示观测图像,目标姿态变化引起刚性模板的变形用特殊正交群矩阵表示,在贝叶斯估计框架下,用跳扩散过程从后验密度中取样,以希尔伯特-施密特范数作为误差特性,对目标姿态进行估计,并分析误差性能。针对激光雷达距离像基于地面目标进行研究,利用Grenander的模式理论,在不同载噪比情况下对车辆姿态进行估计。通过对姿态估计误差的分析,表明该算法能够较准确地估计目标的姿态。     

Surface plasmon-enhanced dual-band infrared absorber for VO_x-based microbolometer application

We propose a periodic structure as an extra absorption layer(i.e., absorber) based on surface plasmon resonance effects, enhancing dual-band absorption in both middle wavelength infrared(MWIR) and long wavelength infrared(LWIR)regions. Periodic gold disks are selectively patterned onto the top layer of suspended SiN/VO_2/SiN sandwich-structure.We employ the finite element method to model this structure in COMSOL Multiphysics including a proposed method of modulating the absorption peak. Simulation results show that the absorber has two absorption peaks at wavelengths λ =4.8 μm and λ = 9 μm with the absorption magnitudes more than 0.98 and 0.94 in MWIR and LWIR regions, respectively. In addition, the absorber achieves broad spectrum absorption in LWIR region, in the meanwhile, tunable dual-band absorption peaks can be achieved by variable heights of cavity as well as diameters and periodicity of disk. Thus, this designed absorber can be a good candidate for enhancing the performance of dual band uncooled infrared detector, furthermore, the manufacturing process of cavity can be easily simplified so that the reliability of such devices can be improved.