机载视觉自主着陆过程中的跑道提取方法

跑道直线参数的准确提取,是机载视觉完成自主着陆过程的重要条件.首先在边缘图像的基础上利用相位编组算法,得到当前边缘图像中大量的线段,根据线段之间的角度,端点距离,以及线段两边的灰度均值,设计了一套规则来定量描述线段之间的亲近性,根据亲近值,将处于同一直线上的短线段首尾连接成长线段.取最长的若干条线段待选,再利用跑道区域的先验知识,主要是跑道内外的灰度对比信息,将位于同一条跑道的两条边缘上的线段识别出来.大量的实际图像结果验证了算法的有效性.     

基于线特征的多时相遥感图像变化检测

多时相遥感图像中利用线特征可以感知道路等线形地物的变化。论文提出一种新的基于边缘特征描述的线特征变化检测算法,首先根据边缘的梯度信息得到变化边缘,并对变化边缘进行编组,形成变化边缘的直线支撑区域,然后通过最小二乘拟合方法从直线支撑区域中提取出变化直线。提出的线特征变化检测算法把边缘的相位和幅度信息作为变化检测的判定依据,从而避免了线的匹配与比较工作,降低了变化检测的算法复杂度,具有很强的实用性。将提出的方法用于多时相遥感图像变化检测,实验结果显示该方法的有效性。     

一种直线段匹配的新方法

直线特征在人造目标和环境中普遍存在,直线段的匹配是三维重建等应用领域的首要解决问题.一般单直线的匹配方法难以解决被部分遮挡直线的匹配问题,提出了一种基于极线约束和RANSAC算法的匹配方法.对直线段上的点运用基于极线约束的匹配方法在另一幅图像中进行点的同名匹配,采用RANSAC算法建立直线模型,剔除野值,得到匹配直线段.本方法能有效地解决图像中被部分遮挡直线段的匹配问题,仿真实验和实际图像实验证实了本算法的正确性和高精度.     

基于改进Hough变换的红外图像直线检测

红外图像像素分辨率低、对比度差等特点使得红外图像的直线检测较为困难.Hough变换具有较强的抗干扰性和鲁棒性,是计算机视觉领域中非常有效的直线检测方法.本文提出一种基于改进Hough变换的红外图像直线检测方法,经过实验验证,在红外图像像素分辨率低、边缘模糊等情况下,该方法能够很好地检测出边缘直线,同时确定边缘直线的端点...     

基于蚁群算法的直线边缘提取方法

提出了一种基于蚁群算法的直线边缘提取方法.利用相邻边缘点的相位信息作为蚁群搜索的启发信息,同时引入终止概率,在不满足搜索条件时终止搜索.迭代搜索完成后,最后根据边缘点上的信息素遗留,提取出直线边缘.实验结果表明,该方法在检测直线边缘的同时,还可以保留边缘的细节,定位直线边缘的端点.     

傅里叶望远术中的相位闭合分析及其仿真

傅里叶望远术是近年来受到广泛关注的一项主动成像技术.它利用直线干涉条纹对目标的傅里叶频谱进行提取,并利用相位闭合技术消除随机相位,最终获取同步轨道目标的高分辨率图像.对傅里叶望远术的基本理论进行了推导,详细阐述了相位闭合实现方法,并对整个过程进行了计算机模拟.仿真实现了对两个目标的频谱扫描并重建了它们的二维灰度图像,充分验证了傅里望远术的正确性和可行性.     

基于高精度景象匹配的SAR平台定位方法

提出一种利用SAR图像与光学基准图高精度匹配实现SAR平台定位的方法。利用成像中间时刻SAR平台与SAR图像中心线上物点在水平面的投影共线的特性,在图像中心线上均匀选取若干点作为匹配点,并与光学基准图进行高精度景象匹配获取它们的物点坐标;根据这些物点坐标估计出图像中心线在当地水平面投影的直线方程;利用直线信息和斜距高度信息计算SAR平台在水平面上的投影点位置,进而计算得到成像中间时刻SAR平台的空间位置。为了进一步提高匹配精度,分别提出对正侧视和斜视SAR图像匹配区域进行几何粗校正的方法。还分析了不同误差因素对平台定位精度的影响,并给出精度估计公式。仿真和实际图像实验结果表明,方法正确可行,具有较高的定位精度,具备工程实用价值。     

基于高精度景象匹配的SAR平台定位方法研究

为了提高SAR平台定位精度,本文提出了一种基于景象匹配的SAR平台定位的方法。该方法利用成像中间时刻SAR平台与SAR图像中心线上物点共线的特性,先在图像中心线上均匀选取若干点作为匹配点,并与光学基准图进行高精度景象匹配获取它们的物点坐标;然后根据这些物点坐标估计出图像中心线在当地水平面投影的直线方程;最后利用直线信息和斜距高度信息计算SAR平台在水平面上的投影点位置,进而计算得到成像中间时刻SAR平台的空间位置。为了进一步提高匹配精度,分别提出了对正侧视和斜视SAR图像匹配区域进行几何粗校正的方法。本文还分析了不同误差因素对平台定位精度的影响,并给出了精度估计公式。仿真和实际图像实验结果表明,本文方法正确可行,具有较高的定位精度,具备工程实用价值。     

基于高阶曲面拟合的边缘检测算法研究

图像的边缘检测是图像分析领域十分重要的基础,在工程应用中占有很重要的地位.提出了一种基于高阶曲面拟合的边缘检测算法.算法首先利用自适应滤波对图像进行了去噪处理,接着通过曲面拟合获取图像的梯度信息,最后用统计方法进行了阈值选取.实验证明该算法得到的边缘图像相对简单,边缘点较少,有利于识别,同时该检测算法也为后续的图像分析、图像理解打下了良好的基础.     

基于单类集成分类器的JPEG通用隐写分析

针对JPEG图像通用隐写检测问题,提出了一种基于单类集成分类器的新方法。算法提取图像DCT块内、块间和小波层内、层间的共生特征以及小波子带系数的直方图特征对图像进行描述,并计算检测图像及其原始估计图像所提共生矩阵和直方图分布的对称交互熵作为隐写分析特征;然后,随机构造若干个特征子空间,利用bootstrap方法构造载体图像训练子集,分别进行单类训练得到数个基分类器;最后,将基分类器的分类结果按多数投票法进行融合作为单类集成分类器的分类结果。实验结果表明,单类集成分类器能显著提高算法的检测效果,而且,本方法相比基于多超球面OC-SVM分类器的单类隐写分析方法,具有更高检测率。     

Reviews

Douglas S. Derrer, We Are All the Target: A Handbook of Terrorism Avoidance and Hostage Survival. Annapolis, MD: US Naval Institute Press, 1992. Pp. x+135, notes, index. $14.95. ISBN 01–55750–150–5

Ian Knight, Zulu: Isandlwana and Rorke's Drift, 22–23 January 1879. London: Windrow & Greene, 1992. Pp.136, 150 illus., incl 8 colour plates, maps, biblio. £35. ISBN 1–872004–23–7

Ian Knight, By the Orders of the Great White Queen: Campaigning in Zululand through the Eyes of the British Soldiers, 1879. London: Greenhill Books and Novato: Presidio Press, 1992. Pp. 272, 17 illus., 1 map. £18.95. ISBN 1–85367–122–3

Manfried Rauchensteiner and Erwin A. Schmidl (eds.), Formen des Krieges: vom Mittelalter zum ‘Low‐intensity’ Conflict’. Graz : Verlag Styria, 1991. Pp.208. DM35. ISBN 3–22–12139–7

Harold J. Kearsley, Maritime Power and the Twenty‐First Century. Dartmouth: Dartmouth Publishing Company, Limited, 1992. Pp.xv + 203, 13 diagrams, index. £32.50. ISBN 1–85521–288–9     

Panjwai: a tale of two COINs in Afghanistan

The US Army has two approaches to counterinsurgency operations in Afghanistan. One is hard, or combat-focused, and the other is soft, or development-focused. This study examines two US Army task forces deployed to Panjwai District, Afghanistan from 2012 to 2013. CTF 4-9 and 1-38 offer a meaningful comparison because they pursued these contrasting approaches among the same population and against the same enemy at the same time and place. The study compares each unit’s approach and finds that neither approach was successful absent the other. The article concludes by recommending further research into combining the approaches at the operational level.     

线性核时频信号表示及其仿真

根据ｃｈｉｒｐ信号在模糊域的特点,本文提出了线性核时频表示方法。这种方法在提高分辨率、消除交叉项以及抑制噪声等方面都具有较高的性能。理论分析和实验结果都证实了这种方法的有效性     

Forecasting a Hurricane: Israeli and American Estimations of the Khomeini Revolution

The surprising ‘Arab Spring’ raises the question as to what would enable national intelligence to provide high quality warnings prior to the eruption of popular revolutions. This article uses new sources of evidence to trace and explain Israel's success in comparison to US failure at correctly estimating the course of the Iranian Revolution in 1977–79. In explaining this variance, the article shows that it was mainly the result of the intimate acquaintance of Israel's representatives in Iran with the local language, history and culture, as well as the ability to communicate with locals – tools which the Americans completely lacked.     

关于教师继续教育培训模式的思考

继续教育作为终身教育的重要组成部分和基本形式,对教师的发展成长意义重大。继续教育工作开展十多年来,取得了一定的成绩,但还存在不少问题,如学习动机较为被动,管理认识不到位,教学内容陈旧空泛,教学方法呆板机械等。随着课程改革的不断深入,继续教育必须采取相应的改进措施,树立以人为本,服务至上的观点,教学内容的前瞻性与实用性并重,教学人员进行整合,教学方法灵活多样,评价考核规范科学等,以此激活受训教师内在的学习动机,更大程度地提高继续教育培训的实际效果。     

用DirectShow实现网络视频

目前市场上的网络监控技术一般用昂贵的硬件设备来支撑,投资较大。在深入研究微软的DirectX9.0的基础上,提出如何用DirectShow软件技术和普通的数字摄像头来实现网络视频的监控和实现技术,内容涉及通信协议、视频的编码与解码技术、视频的编码格式和COM组件编程技术等,最终的实验结果令人满意,且费用低廉,技术可靠,为在高速局域网内构建视频监控系统提供有效的技术支持。     

Interpreting the Ribchester Helmet

In 1796 a 13-year-old boy playing on wasteland behind his father’s house in Ribchester, Lancashire discovered an assemblage of over 30 Roman artefacts, including a decorated brass helmet. Although partially corroded the Ribchester helmet is a fine example of a first-century AD cavalry sports helmet. This article considers how the interpretation of the helmet has evolved since its discovery. The multi-faceted iconography of the helmet with its mural crown diadem is that of an elite soldier and is paralleled in other examples of cavalry sports helmets of the Ribchester type. The long-neglected imagery on the helmet bowl is reinterpreted and seen not as a haphazard collection of randomly placed combatants but as a highly structured, symmetrical composition specifically designed to be viewed from different directions.     

Putin – the masked nemesis of the strategy of ambiguity

Recent events demonstrate the complex and adaptive approach employed by Russia to reassert influence in Europe. The changing face of Russia’s strategy commenced in 2007 when it launched a crippling cyber-attack against Estonia. This was followed by a large Russian conventional attack against Georgia in 2008, occupying two large areas of the nation. 2014 witnessed the Russian annexation of Crimea where in just a week, Russia seized control of Crimea “without firing a shot.” The annexation of Crimea was rapidly followed by a Russian inspired and led subversive war in eastern Ukraine. The common thread among these diverse Russian operations is its use of ambiguity to confound and confuse decision makers in the West.     

Desert insurgency: lessons from the third Tuareg rebellion

This article provides an in-depth examination and analysis of the 2006–2009 Tuareg rebellion in Mali and Niger. It identifies the underlying reasons behind the rebellion, explores contrasting counter-insurgency (COIN) strategies employed by the two governments, and presents some lessons learned. While both COIN approaches ultimately produced similar peace settlements, the article argues that the Malian strategy of reconciliation combined with the selective use of force was far more effective than the Nigerien iron fist approach at limiting the size and scope of the insurgency and producing a more sustainable peace. It concludes by looking at the role of external actors, particularly the United States, and how the failure to internationalize the conflict was actually more beneficial to the local COIN effort, as well as to the longer strategic interests of the United States in the region.