A new class of stereoregular vinylene‐arylene copolymers with double‐decker silsesquioxane in the main chain

A synthesis of a new macromolecular class of vinylene‐arylene copolymers with double‐decker silsesquioxane in the main chain is presented. Two transition‐metal‐catalyzed processes, which is silylative‐coupling copolycondensation (SCC) and ADMET copolymerization of divinyl‐substituted double‐decker silsesquioxanes (DDSQ‐2SiVi) with selected diolefins, are reported to be highly efficient tools for the formation of stereoregular copolymers containing DDSQ‐silylene‐vinylene‐arylene units. The copolymeric products are studied in terms of their structural, thermal, and mechanical properties. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1044–1055     

双波段红外探测设备同靶标共航路测试方法研究

针对双波段红外探测设备不同波段的探测要求,利用曳光管双波段辐射特性,提出无人机加载曳光管作为低空移动光电靶,实现同一靶标满足双波段测试要求;通过对无人机航路距离和航向的统筹设计,实现同一个飞行航次满足作用距离和目标数据精度等多个测试项目;文中对目标航迹真值精度进行深入分析,总结出在不同条件下,航路、航向及布站等相关参数的关联和设置方法,为该测试项目组织实施提供充分的技术准备和选择空间。     

Modeling the drain current and its equation parameters for lightly doped symmetrical double-gate MOSFETs

A 2D model for the potential distribution in silicon film is derived for a symmetrical double gate MOSFET in weak inversion. This 2D potential distribution model is used to analytically derive an expression for the subthreshold slope and threshold voltage. A drain current model for lightly doped symmetrical DG MOSFETs is then presented by considering weak and strong inversion regions including short channel effects, series source to drain resistance and channel length modulation parameters. These derived models are compared with the simulation results of the SILVACO (Atlas) tool for different channel lengths and silicon film thicknesses. Lastly, the effect of the fixed oxide charge on the drain current model has been studied through simulation. It is observed that the obtained analytical models of symmetrical double gate MOSFETs are in good agreement with the simulated results for a channel length to silicon film thickness ratio greater than or equal to 2.     

The impact of gate misalignment on the analog performance of a dual-material double gate junctionless transistor

The analog performance of gate misaligned dual material double gate junctionless transistor is demonstrated for the first time. The cases considered are where misalignment occurs towards source side and towards drain side. The analog performance parameters analyzed are: transconductance, output conductance, intrinsic gain and cut-off frequency. These figures of merits (FOMs) are compared with a dual material double gate inversion mode transistor under same gate misalignment condition. The impacts of different length of control gate (L₁) for a given gate length (L) are also studied and the optimum lengths L₁ under misalignment condition to have better analog FOMs and high tolerance to misalignment are presented.     

基于DP-LIBS铁合金中碳元素特征谱线的研究

采用双脉冲和单脉冲激光,对空气中标准铁合金样品中碳元素的激光诱导实验,研究两种方式下形成的光谱。双脉冲激光诱导击穿光谱采用两束激光,在第一束激光脉冲的基础上加入第二束高压激光脉冲,对等离子体进行二次激发。通过对比研究发现:双脉冲激发技术延长了原子特征辐射的有效时间,提高了获取信号的信噪比,增强了发射光谱的信号强度,提高了信号的稳定性。此外,通过分析影响双脉冲信号增强程度的因素,研究了脉冲宽度和延迟时间以及激发能级对光谱增强程度的影响。     

刑侦日盲紫外折衍混合变焦光学系统设计

为了满足刑侦过程中紫外光学系统远距离搜索、近距离拍照的需求,采用二元衍射元件和非球面元件,设计了一种日盲紫外机械补偿变焦光学系统,其中焦距为40mm~80mm,F数为4,工作波段为0.24μm~ 0.28μm。选用S8844-0909型2.54cm紫外CCD,像元尺寸为24μm×24μm,对应视场角为6°~12°。系统由7块透镜组成,结构简单、体积小巧。结果表明,在整个变焦范围内,后截距10mm处,截止空间频率21cycles/mm时,各视场的光学调制传递函数均在0.7以上,接近衍射受限曲线,畸变小于5%,像质优良,像面稳定。该设计能满足光学系统的总体设计要求。     

电子束辐照在POSS／环氧树脂二元体系TEM观察中的作用

本文以POSS／环氧树脂的二元体系为主体,研究了电子束辐照对该二元体系在透射电镜观察中的作用。研究表明,随着电子束辐照强度和辐照时间的增加,二元体系中POSS分散相的衬度越来越明显,得到的TEM图像也更加清晰。本文采用TEM图像的相对灰度值定量研究了电子束辐照时间对图像清晰度的影响,探索了电子束辐照对该二元体系TEM像衬度提高的原理。     

DS-SS/EBPSK调制的码分多址研究

为了实现直序扩频扩展的二元相移键控(DS-SS/EBPSK)调制的多址通信,研究了一种DS-SS/EBPSK调制的码分多址实现方法.首先对DS-SS/EBPSK调制信号进行分析,公式化表述了DS-SS/EBPSK的调制过程,得到了可用于解扩和码分多址的等效扩频序列;在此基础上,设计了相关接收机对DS-SS/EBPSK调制信号进行检测,利用不同用户扩频序列互相关很小的特点实现多址传输;最后以m序列为例,仿真了期望用户的误码性能与用户数量和m序列周期长度的关系.仿真结果验证了此种码分多址实现方式的可行性,同时也表明多用户的于扰程度取决于扩频序列之间的互相关性.     

融合矢量量化与LBP的图像检索算法

基于内容的图像检索算法一直是图像领域研究的热门课题,因此提出一种新的融合矢量量化与LBP的图像检索算法。首先,将彩色图像转化到HSI颜色空间,进行矢量量化编码,统计图像码字出现的频数,形成颜色直方图,完成颜色特征的提取;然后,再将彩色图像转化成灰度图像,利用局部二进制模式(LBP)算法提取纹理特征;最后,相似度计算采用颜色特征和纹理特征相似度加权平均,并且改变颜色特征和纹理特征的权值,多次实验,得到使查准率最高的权值。实验结果表明,算法能有效地提升图像检索性能。     

基于局部二值模式和四元数的行人检测

局部二值模式(LBP)特征具有光照不变性、旋转不变性及计算简单等特性,能有效表示行人特征,广泛应用于行人检测。LBP 特征的提取方法通常基于灰度图像,如果用于彩色图像,则没有充分考虑各通道之间的相关性,不能保证行人检测的准确性。为此,我们对彩色图像的红、绿、蓝三通道的LBP 特征,以四元数的形式表示,利用四元数的性质,提出一种P-LBP特征,再利用k-最近邻算法训练分类器。该方法在INRIA 数据集上进行实验,与HOG、S-LBP、F-LBP、HOG-LBP特征进行比较,具有更好的效果。