船用双馈笼锥组合式宽带天线

实验研究了一类采用组合复用、双端馈电和套筒结构匹配等技术设计的用于船用短波超短波通信的小型宽带天线,详述了各物理结构参数对天线性能的影响.据此设计的天线在超过5个倍频程的带宽范围内,电压驻波比(VSWR)基本低于2.5,而尺寸远小于相同用途的传统盘锥、discage等天线.     

类铍离子(Z=21～92)的M1跃迁的X射线激光光谱的理论研究

根据全相对论多组态方法 ,采用GRASP2 程序 ,系统计算了类铍离子等电子序列 (Z =2 1～ 92 )禁戒跃迁(1s2 2 pnd) 1 (n=3～ 4) (1s2 2 p3-d )0 的能级间隔、自发跃迁系数和加权振子强度。结果表明 :高离化度 (q≥ 5 1)离子激发态禁戒跃迁的跃迁几率与中性原子的电偶极E1 的跃迁几率相当。在ICF和MCF高温激光等离子体中 ,其跃迁过程不容忽视。同时 ,对在双电子复合机制下实现粒子数反转的X射线激光工作物质进行了初步探讨。     

基于证据方差的加权证据组合

DS证据理论在决策级信息融合中有着广泛应用.针对证据组合时的某些反直观结果问题提出一种新的基于证据方差的序贯式加权证据组合方法.首先基于Jousselme证据距离定义了证据方差.每一步证据组合时,依据当前既有证据组合结果序列的方差及当前步新证据加入后的序列方差来生成权重.基于所获权重修正新到证据及前一步组合结果,最后利用Dempster规则完成当前步证据组合.算例分析表明所提方法是合理有效的.     

一种V波段近距探测毫米波功率放大器设计

介绍了一种用于弹上近距探测系统,工作在非大气窗口波段的功率放大器,该功放基于MMIC实现电路设计,采用端口驻波较好的两路电桥,由多级级联实现功率合成,波导到微带采用两路微带探针经波导E面插入,完成波导立体传输线与微带集成传输线间的过渡转换,同时又实现同相宽带功率分配/合成。实际的测试表明,在工作带宽内,指标满足设计要求...     

COMBINATORIAL DESIGN APPROACHES FOR AUTOMATIC TEST GENERATION

The n-way combination testing is a specification-based testing criterion, which requires that for a system consisted of a few parameters, every combination of valid values of arbitrary n(n ≥ 2) parameters be covered by at least one test. This letter proposed two different test generation algorithms based on combinatorial design for the n-way coverage criterion. The automatic test generators are implemented and some valuable empirical results are obtained.     

基于时域和空域混合的低信噪比视频降噪算法及其分析

论述了几种基于时域和空域混合的对低信噪比视频图像进行降噪处理的算法.考虑单独使用时域或空域降噪算法对视频图像进行处理的缺点和不足.在时域上,由于视频图像帧与帧之间有较强的相关性,采用递归加权算法;在空域上,分别采用第二代Curvelet变换理论的Wrap算法( Wrapping-Based Transform)、全变差(TV)算法、Lee降噪算法、基于偏微分方程各向同性非线性扩散去噪算法(PM-AOS算法)以及中值滤波等降噪算法.实验结果表明时域和空域混合的降噪算法可提供较好的视觉效果,较好地保留视频图像的边缘、纹理等细节信息,超过单独使用时域或空域对视频图像降噪的算法,且部分算法处理时间相对较短,具有在硬件平台上移植的可行性.     

基于能动分块反射镜的七路激光阵列倾斜校正与相干合成实验研究

提出了一种基于能动分块反射镜(ASM)的激光阵列相位控制新方法,用以解决激光主振荡功率放大(MOPA)器相干合成技术中的空间光束倾斜校准与输出端相位调制两大关键问题。介绍了7单元能动分块反射镜实现空间光调制的原理,并采用该器件成功验证了7路光束合成的方案。实验采用六棱反射锥进行光束合成,并采用两套控制回路分别实现了倾斜与平移校正,获得了小于25μrad和λ/10的校正精度。闭环后,获得了主瓣占总功率31.73%的高质量相干耦合激光输出。     

一种新的光CDMA编码方案

本文以光正交码（OOC）为基础,提出了一种新的光CDMA编码方案。这种新的方案充分利用了已有的成熟的OOC编码技术,可以灵活方便地构造出光正交跳频以及光正交时间/频率组合码。这种新的地址码具有良好的自相关、互相关性能、较大的容量和良好的系统性能,还可以灵活地和现有的光天源器件相匹配。     

基于点云簇组合特征的激光雷达地面分割方法

针对三维激光雷达在地面分割过程中存在分割不足和过分割的问题,提出一种基于点云簇组合特征的激光雷达地面分割方法.首先将三维点云投影到扇形栅格中进行连通域聚类,将梯度相差较小的栅格聚为一类.然后根据路面点云符合平面和直线几何特征的特点,对每一簇进行特征值计算以挑选路面栅格簇的候选簇,接着对其进行径向方向上的梯度检查以剔除误...     

Facial micro-expression recognition based on accordion spatio-temporal representation and random forests

Micro-expressions are very brief involuntary facial expressions which appear on the face of humans when they unconsciously conceal an emotion. Creating a solution allowing an automatic recognition of the facial micro-expressions from video sequences has garnered increasing attention from experts across such different disciplines as computer science, security, and psychology. This paper offered a solution to facial micro-expressions recognition, based on accordion spatio-temporal representation and Random Forests. The proposed feature space, called “Uniform Local Binary Patterns on an Accordion 2D representation of sub-regions presented by a Pyramid of levels (LBPAccP^u2)”, exploits the effectiveness of uniform LBP patterns applied on an accordion representation of sub-regions at different sizes. Random Forests were used to select the most discriminating features and reduce the classification ambiguity of similar micro-expressions through a new proximity measure. The main objective of our paper was to demonstrate that the use of few features could be more efficient to produce a strong micro-expression recognition classifier that outperforms the approaches that rely on high dimensional features space. The experimental results across six micro-expression datasets show the effectiveness of the proposed solution with an accuracy rate that can reach 81.38% on CasmeII dataset. Compared to some famous competitive state-of-the-art approaches, the proposed solution proved its performance thanks to its accuracy rate as well as the number of features it uses.