卫星导航信号无模糊抗多径码相关参考波形设计技术

针对目前卫星导航接收机码环多径抑制技术在二进制偏移副载波类信号下鉴别曲线可能出现多个稳定跟踪位置,导致接收机存在伪距测量的系统性误差的问题,提出最优鉴别曲线设计技术,采用奇异值优化的最小二乘方法,设计无多余跟踪点的本地码相关参考波形。从多径误差包络和跟踪精度两方面,对基于最优鉴别曲线的二进制偏移副载波信号码相关参考波形的设计性能进行验证评估。仿真结果表明：该方法可实现二进制偏移副载波信号在有限接收带宽下的无模糊鉴别曲线设计。以前端带宽为8.184 MHz时的BOC(1,1)信号为例,设计的码相关参考波形相比W2波形,多径误差包络面积增加了61.8%,而跟踪精度提高了4~5 dB。     

动力翼伞风扰补偿高度控制方法

外界风场是影响翼伞高度跟踪精度的最主要扰动因素。针对该问题,建立了动力翼伞的八自由度模型,并在传统自抗扰控制的基础上,设计一种基于风场前馈补偿的改进抗扰控制器,对外界的风场干扰进行针对性补偿,实现翼伞系统的高度跟踪控制。在通过仿真实验对控制器进行初步验证的基础上,进行了翼伞系统的实际飞行实验。在实际飞行环境下,仿真中所调节的控制器参数可直接应用于实际飞行实验,翼伞系统的平均高度跟踪误差在2.5 m以内,证明所设计的控制器存在一定的实际应用价值。     

基于PDA-UKF的杂波环境下单目标跟踪算法

提出将概率数据关联算法和不敏卡尔曼滤波相结合,用于杂波环境下的单目标跟踪。该算法同时解决了测量方程非线性情况下的滤波问题和杂波环境下的目标跟踪问题。给出了PDA-UKF算法的仿真过程,提供了一个基于距离、方位角、俯仰角的目标跟踪问题的仿真算例。理论分析与仿真结果均表明,该算法提高了滤波的稳定性和跟踪的精确性,具有较高的实用价值和广泛的应用前景。     

密集杂波环境下用于多目标跟踪的改进PDA算法

概率数据关联(PDA)算法在密集波环境下跟踪单目标时具有良好的效果,但当跟踪多目标时,由于未能考虑相邻目标间的相互影响,因此效果不佳,针对PDA算法的不足,基于多目标跟踪中相邻目标间相互影响的特点,提出了一种新的改进概率数据关联(NIPDA)算法.新算法引入量测J属于目标t的概率Bjtk,并用其对关联概率进行修正,从而在计算互联概率时考虑了相邻目标间的影响.仿真结果表明,新算法在计算量与PDA算法相近的情况,提高了目标跟踪成功率.     

天地预警系统与机敏传感信息网

建立高效的天地预警系统对于赢得现代立体战争的胜利有着极其重要的意义。探讨了天地预警系统与机敏传感信息网 (Sm art Sensor Web)的构成 ,结合我国的部分研究现状 ,较详细地阐述了设计与构造天地预警系统所需解决的若干关键技术问题。     

雷达模拟器的设计与实现

采用模拟器进行武器装备的维修和操作训练是当今装备发展趋势。介绍了雷达模拟器的设计思想、组成和各部分功能 ,分析了模拟器的工作方式。该模拟器解决了目标的实时生成、控制、测量和显示等关键问题 ,完整实现了对某型雷达的功能模拟和操作训练。目前 ,该系统已成功应用于院校教学和部队训练 ,取得了较好的效果。     

基于网络和主机相结合的入侵检测技术

首先介绍了基于主机和基于网络的两种入侵检测系统的功能原理 ,在分析这两种系统功能原理的基础上 ,提出了基于网络和主机相结合入侵检测系统的工作流程和工作原理 ,进而阐明了当系统检测到有入侵情况下的应对措施 ,采用人工神经网络的入侵检测算法 ,提高了对入侵类型的判别能力 ,保证应对措施的正确 ,确保了系统的安全性。     

The building evacuation problem with shared information

In this article, the Building Evacuation Problem with Shared Information (BEPSI) is formulated as a mixed integer linear program, where the objective is to determine the set of routes along which to send evacuees (supply) from multiple locations throughout a building (sources) to the exits (sinks) such that the total time until all evacuees reach the exits is minimized. The formulation explicitly incorporates the constraints of shared information in providing online instructions to evacuees, ensuring that evacuees departing from an intermediate or source location at a mutual point in time receive common instructions. Arc travel time and capacity, as well as supply at the nodes, are permitted to vary with time and capacity is assumed to be recaptured over time. The BEPSI is shown to be NP‐hard. An exact technique based on Benders decomposition is proposed for its solution. Computational results from numerical experiments on a real‐world network representing a four‐story building are given. Results of experiments employing Benders cuts generated in solving a given problem instance as initial cuts in addressing an updated problem instance are also provided. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

A Question of ‘Government’ Control: Afghanistan DDR Programs Since 2001

Since the fall of the Taliban in late 2001, the Islamic Republic of Afghanistan (GIRoA), the United States, the United Nations, and the International Security Assistance Force (ISAF) have funded and led three different Disarmament, Demobilization, and Reintegration (DDR) programs. Despite a significant investment in time and treasure, all of them have failed to significantly reduce the number of insurgents or arbaki (militia). This article explores why these programs failed despite incorporating ideas from the prominent DDR schools of thought. Utilizing Stathis Kalyvas’ theory of The Logic of Violence in Civil War as a lens, this article argues that GIRoA and ISAF did not have sufficient control of territory to entice insurgents or arbaki to reconcile and/or reintegrate with the government. Further, in areas GIRoA nominally controlled in northern and western Afghanistan, regional powerbrokers who controlled these areas balked at these programs.     

载机扰动下SAR/GMTI旋转目标微多普勒特性分析

目标微动部件激励的雷达微多普勒信号稳定而独特,反映了该目标的本质特征。针对采用相位中心偏置技术(DPCA)的SAR/GMTI系统,研究存在载机扰动下的旋转目标的微多普勒特性。构建飞行平台与微动目标的几何模型,推导旋转目标的微多普勒信号模型,分析典型的载机纵向扰动对微多普勒时频特性构成的影响;并通过仿真实验,验证了上述理论分析的正确性。