灵巧噪声干扰本质及相关基本问题探讨

为正确理解和实施灵巧噪声干扰,基于匹配滤波器理论对灵巧噪声干扰的本质含义进行了分析。指出,灵巧噪声干扰的本质含义是使干扰由多个分量组成,并且使干扰中的每一个分量的频谱都与雷达发射信号的频谱相同,从而使干扰中的每一个分量的功率利用效率都达到最大。最后,从理论和实践2个角度,阐述了与灵巧噪声干扰相关的基本问题,并进行了相应的分析。     

基于Coherent Point Drift方法的SAR图像散射中心匹配

散射中心匹配是当前散射中心用于SAR图像目标识别的一个主要技术途径.散射中心匹配的难点在于散射中心特征存在的误差和缺失.Coherent Point Drift (CPD)方法从概率密度估计的角度解决点模式匹配问题,能够较好地考虑散射中心的误差和缺失.本文将CPD方法用于散射中心匹配,并在此基础上引入车辆目标SAR图像方位角估计先验信息和散射中心属性信息,以提高散射中心匹配的准确性和稳健性.MSTAR数据实验说明了该方法的有效性.     

雷达定时脉冲近距离传输的分析与电路设计

通过分析比较多种时间同步技术,对与雷达距离上百米的系统,采用有线传输雷达定时脉冲信号的方式来实现快速的时间同步。针对雷达脉冲信号边沿跳变迅速,在传输过程中存在延时、反射和畸变等问题,借助Cadence仿真软件对信号传输过程进行了仿真分析,设计了合理的传输电路。实验证明本方案结构简单,抗干扰能力强,同步时间可以达到亚微秒级,在雷达信号检测模拟器、雷达诱饵和雷达组网中都有着重要应用。     

Dynamic pricing and matching in ride-hailing platforms

Ride-hailing platforms such as Uber, Lyft, and DiDi have achieved explosive growth and reshaped urban transportation. The theory and technologies behind these platforms have become one of the most active research topics in the fields of economics, operations research, computer science, and transportation engineering. In particular, advanced matching and dynamic pricing (DP) algorithms—the two key levers in ride-hailing—have received tremendous attention from the research community and are continuously being designed and implemented at industrial scales by ride-hailing platforms. We provide a review of matching and DP techniques in ride-hailing, and show that they are critical for providing an experience with low waiting time for both riders and drivers. Then we link the two levers together by studying a pool-matching mechanism called dynamic waiting (DW) that varies rider waiting and walking before dispatch, which is inspired by a recent carpooling product Express Pool from Uber. We show using data from Uber that by jointly optimizing DP and DW, price variability can be mitigated, while increasing capacity utilization, trip throughput, and welfare. We also highlight several key practical challenges and directions of future research from a practitioner's perspective.     

无人飞行器异源图像匹配辅助惯性导航定位技术综述

无全球定位系统下高精度定位与导航是飞行器实现自主侦查、巡航与打击的关键。视觉导航具有被动、低成本、能避免累积误差等优点。视觉导航与惯性导航融合更能够发挥出各自的优势,达到高精度定位的目的。总结了异源图像匹配辅助惯性导航的飞行器定位技术的发展历程; 从相机-惯导标定技术、异源图像匹配、姿态解算、数据融合和后端优化五个方面详细阐述了异源图像匹配辅助惯性导航的飞行器定位的关键技术; 指出了基于深度学习的异源图像匹配与惯性导航两种无源定位组合导航系统融合技术等四个未来可能的发展方向,可为实现异源图像匹配辅助惯性导航飞行器定位技术提供参考。     

Reclaiming the local in EU peacebuilding: Effectiveness,ownership, and resistance

ABSTRACT

Since the early 2000s, the “local turn” has thoroughly transformed the field of peacebuilding. The European Union (EU) policy discourse on peacebuilding has also aligned with this trend, with an increasing number of EU policy statements insisting on the importance of “the local.” However, most studies on EU peacebuilding still adopt a top-down approach and focus on institutions, capabilities, and decision-making at the EU level. This special issue contributes to the literature by focusing on bottom-up and local dynamics of EU peacebuilding. After outlining the rationale and the scope of the special issue, this article discusses the local turn in international peacebuilding and identifies several interrelated concepts relevant to theorizing the role of the local, specifically those of effectiveness, ownership, and resistance. In the conclusion, we summarize the key contributions of this special issue and suggest some avenues for further research.     

基于共进化的多任务分配与调度

在考虑多种约束关系基础上 ,提出一种并行与分布式系统中多约束关系的任务分配与调度的共同进化遗传算法。仿真试验结果表明所给算法比传统单种遗传算法更能有效地进行多任务分配与调度 ,具有一定的工程价值     

辐射叶加载的短波宽带鞭状天线优化设计

提出一款具有多层辐射叶结构的新型鞭状天线,在10 m鞭状天线体上设置不同的辐射叶层数、半径、长度、分支数、仰角及其分布情况,研究其对天线辐射性能的影响,综合考虑选择一套最合适的辐射叶结构,并为天线进行双加载和宽带匹配网络的算法优化。仿真结果表明,与现有的普通宽带鞭状天线相比,增益和效率得到了普遍提高,在低频段增益最高提高了3 dB,效率最高提高了5%;在高频段增益最高提高了5 dB,效率最高提高了35%,方向图上翘也得到了一定的抑制,为改善现有的宽带鞭状天线提供一种新的结构设计方法。     

Adaptive random search for continuous simulation optimization

We present, analyze, and compare three random search methods for solving stochastic optimization problems with uncountable feasible regions. Our adaptive search with resampling (ASR) approach is a framework for designing provably convergent algorithms that are adaptive and may consequently involve local search. The deterministic and stochastic shrinking ball (DSB and SSB) approaches are also convergent, but they are based on pure random search with the only difference being the estimator of the optimal solution [the DSB method was originally proposed and analyzed by Baumert and Smith]. The three methods use different techniques to reduce the effects of noise in the estimated objective function values. Our ASR method achieves this goal through resampling of already sampled points, whereas the DSB and SSB approaches address it by averaging observations in balls that shrink with time. We present conditions under which the three methods are convergent, both in probability and almost surely, and provide a limited computational study aimed at comparing the methods. Although further investigation is needed, our numerical results suggest that the ASR approach is promising, especially for difficult problems where the probability of identifying good solutions using pure random search is small. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

一类具有时滞的病毒动力学模型分析

研究一类具有时滞的病毒动力学模型。研究了系统解的有界性;讨论了各个非负平衡点的局部稳定性,应用比较定理得到了各非负平衡点全局渐近稳定的充分条件。