相位差变化率的快速高精度测量及精度分析

由于阵元间相位差变化率这一观测量与通道不一致性关系不大,信号到达两阵元间的相位差变化率常用于无源定位测量中。提出了一种新的快速高精度的相位差变化率测量方法,利用分时间片思想,首先通过对无模糊相位差进行一次相位平移,得到各个时间片含模糊的相位差值;然后对得到的各个时间片的含模糊相位差进行一次相位平移,得到各时间片间相对无模糊的相位差;最后对相对无模糊相位差采用最小二乘算法求得相位差变化率。理论分析和仿真实验表明,本算法可以很好地解决测量中由于相位模糊造成的相位差抖动问题,能够在短时间内得到高精度相位差变化率信息,可以满足定位要求。     

脉冲群间多普勒频率变化率的高精度测量算法

提出了一种脉冲群间多普勒频率变化率的高精度测量算法,该算法利用脉冲群内相邻脉冲对间的互相关函数估计脉冲群模糊频率,在连续脉冲群间选择任一相同模糊频率进行解模糊得到各脉冲群相对频率,由于这些相对频率包含相同的模糊,从而可以利用差分或滤波算法得到脉冲群间多普勒频率变化率。该算法具有相对频率估计精度高、解模糊过程简单、运算量小、多普勒频率变化率测量精度高等优点。计算机仿真和地面缩比试验均证明了该测量算法的有效性。     

利用波达角及变化率对固定辐射源的无源定位

提出了一种利用波达方向角(包括方位角与俯仰角)及其变化率信息对固定辐射源进行单站无源定位的算法,对可观测性条件与定位误差的影响因素进行了分析,并将融入波达方向角变化率信息的EKF算法用于载机在航迹上的多次测量定位,并通过仿真将该算法与只测角定位算法进行了比较.     

基于方向角及其变化率测量子集的单站无源定位

根据目标辐射源的方向角及其变化率信息所构成的不同测量子集及建立的目标测量模型,提出了一种基于数据融合的优化定位处理方案,对各个单测量子集所得到不同的目标位置及测量误差值进行数据融合处理,分析比较了多测量子集融合处理后与单测量子集的定位性能,仿真分析表明,该优化定位处理方案可有效地提高无源探测系统的目标定位精度,减小探测盲区.     

一种BPSK相参脉冲信号多普勒频率变化率测量方法

BPSK信号广泛应用于新体制雷达中,测量BPSK信号中包含的多普勒频率变化率信息是单站无源定位与跟踪的关键技术.通过对BPSK信号平方消除了相位调制对参数估计的影响,并利用离散傅立叶变换进行脉冲间相参积累,算法具有计算量小、多普勒频率变化率估计精度高的优点.计算机仿真结果表明参数估计的精度能达到单站无源定位与跟踪系统的精度要求.     

数字式相位差测量方法及精度分析

相位差变化率是最近提出的用于快速无源定位的观测量。该文研究相位差的高精度测量方法 ,提出了一种正交双通道数字式的相位差测量方法。通过对信号频谱的分析 ,计算了测量系统输出的信噪比 ,从而得出了相位差测量的理论精度 ,随后进行仿真分析验证了理论精度。理论分析和仿真实验证明 ,论文提出的方法可以实现高精度的相位差测量     

空间预警视线系统误差对弹道导弹预警精度估计分析与研究

在空间预警系统中,为了降低系统预警精度受视线测量系统误差的影响,必须对仪器进行定标,因此需要深入对视线误差进行讨论。本文在对视线误差深入研究的基础上,从理论上讨论了视线误差对发射点、射向、落点估计结果的影响,得出系统误差变化率是影响预警结果的重要因素之一,并针对常值系统误差、线性系统误差以及周期系统误差进行了相应的预警仿真计算,从而为几何定标方案的确定提供支持。     

基于来袭鱼雷方位变化率的制导类型识别技术

对来袭鱼雷的制导类型进行识别是水面舰艇实施有针对性鱼雷防御的前提条件,方位变化率则可作为类型识别的一个重要的识别依据。首先,从不同类型潜射鱼雷的发射方式和弹道特征入手,分别推导出潜射直航鱼雷、声自导鱼雷、尾流自导鱼雷方位变化率的表达式。其次,仿真分析了不同类型潜射鱼雷方位变化率的影响因素。最后,在给定的态势下,给出了四种不同类型潜射鱼雷方位变化率随雷舰距离的变化规律曲线。仿真结果能为鱼雷制导类型识别提供一定的参考依据。     

临近空间高超声速滑翔弹跟踪模型

为了提高临近空间高超声速滑翔目标的跟踪精度,基于目标的航迹倾角变化规律建立了一种新的机动模型。为了在雷达测量直角坐标系下估计目标的位置和速度,分析了目标的弹道剖面角,基于航迹倾角变化率和倾角变化率有相近似的变化规律,提出用倾角代替航迹倾角,将倾角变化率描述为零均值正弦自相关随机过程建立角度域的Markov模型,然后将角度关系映射到位置维度建立空间模型。为了使得系统总体状态模型线性,将模型拆分为前端的角度子滤波器和后端的位置子滤波器,由角度滤波器驱动位置滤波器联合跟踪滤波。通过仿真设置了模型的参数,实验结果表明其模型具有更好的跟踪精度。     

一种基于吞吐量变化的OpenFlow网络自适应测量算法

以OpenFlow为代表的软件定义网络(SDN)通过将控制平面和数据平面分离来简化网络任务管理。OpenFlow周期性通过控制器对交换机转发的流量进行信息统计,依据统计信息可以进行网络测量。由于周期性的测量在网络流量突发时会导致测量的准确性降低,在网络状态平稳时控制器与交换机间的资源浪费。针对以上问题,提出一种基于吞吐量变化的自适应的网络测量算法。该算法通过计算吞吐量的变化率,动态地调整测量周期,保证了网络波动时测量的准确性,并在网络平稳时降低了控制器的开销。最后通过仿真实验与周期性的测量进行比较,实验结果表明自适应测量算法在网络波动时能够及时的发现网络变化,同时该方法的测量开销比周期性测量开销大大减少。     

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     

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.     

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.     

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.