基于带有事件触发机制的集员滤波的RSSI室内移动定位

在室内移动定位系统中,由于待定位节点易受统计特性未知的噪声干扰影响,采用Kalman滤波和粒子滤波等经典的噪声抑制方法,已无法有效满足室内定位精度不断提升的要求.针对这一问题,提出了一种基于事件触发的集员滤波室内移动定位算法.首先,针对基于接收信号强度指数(RSSI)测距误差导致传统三边定位算法无法获取可行解的问题,提...     

近圆太阳同步卫星轨道倾角偏差的影响和调整

以某近圆太阳同步轨道卫星为例,分析了倾角偏差引起的降交点地方时的漂移规律及影响。为将降交点地方时漂移限制在允许的范围内,给出了轨道倾角调整方案,仿真实验结果表明控制方案有效。     

一种基于多无人机的中继节点布置问题建模与优化方法

针对战场环境下急需在无法通信的节点间构建有效通信链路的情形,使用多无人机作为中继节点,建立了中继节点布置(RNP)问题模型。模型以中继链路有效和无人机安全为约束,以中继布置点位置及相应的无人机为输出,不但考虑了使用的中继无人机数量,还考虑了构建中继链路花费的时间。考虑到该问题是难以求解的混合整数多目标优化问题,同时在紧急应用情形下,要求求解算法快速有效,建立了一种多项式时间中继节点布置算法(PTRPA)。仿真实验验证了所提模型确实能够在更短的时间内完成有效中继链路构建;通过Monte-Carlo方法对比和分析不同因素对PTRPA算法、随机抽样算法、遗传算法求解该问题的结果性能和时间性能的影响,验证了PTRPA算法不但能够给出接近最优的解,且快速有效,满足战场决策需求。     

缝纫/RFI层合板单钉连接性能计算研究

本文建立了三维有限元分析模型,对缝纫层合板的单钉连接性能进行了理论分析,模拟了钉孔受挤压边缘附近一些典型的针脚位置情况．计算得到钉孔周同的平均径向应力和层间应力分布;并且应用三维点应力损伤判据,得到各种典型针脚位置情况下的缝纫层合板初始挤压破坏强度。研究结果表明,计算结果和试验结果吻合较好,证明该模型能有效地分析缝纫层合板单钉连接性能。且不同针脚位置对缝纫层合板机械连接性能确有重要的影响。     

半球谐振陀螺全角模式信号处理控制方法

介绍了在信号处理的过程中,施加对波腹点、波节点的控制以及谐振频率实时跟踪,从而在谐振振型实时进动的情况下保证谐振振型的稳定,降低陀螺敏感误差;同时对两路相互正交的谐振子谐振信号进行提取和信号处理,得到谐振滞后角度以及陀螺所在载体的转动角度。对该方法进行了数值建模仿真,验证了该方法的可行性。     

基于场景识别的惯性基类脑导航方法

针对无人机导航中惯性器件产生的漂移误差不断随时间累积进而影响导航精度的问题,以仿生类脑导航为研究背景,提出了一种新的导航方法。与传统导航策略不同的是,该方法从周期性校正累积位置误差的角度出发,采用设置位置细胞节点的思路,利用训练好的卷积神经网络模型在细胞节点处进行图像匹配,从而在位置细胞节点处实现惯导位置漂移误差校正。同时,建立节点之间的漂移误差模型,调整误差方程系数,以达到修正漂移误差的目的。最后,基于无人机飞行实验结果验证了该方法对自主导航的有效性和鲁棒性,该方法能够有效提高无人机导航的精度。     

开关点预置最优SPWM变换器控制方案研究

开关点预置的正弦脉宽调制变速恒频电源,对开关点进行最优设定,使得输出电压性能优良。由于ＧＴＲ的开关频率限制,传统的开关点预置控制方案为９块波开关点预置最优ＳＰＷＭ控制方案。本文详细地讨论了开关点预置ＳＰＷＭ控制方案的理论,并针对以ＩＧＢＴ作为主功率模块的变换器,通过提高斩波频率,采用１７块波的开关点预置最优ＳＰＷＭ控制方案,进一步提高了输出电压质量和输出滤波器的谐振频率,减轻了输出滤波器体积重量,     

Bifurcation analysis and stability design for aircraft longitudinal motion with high angle of attack

Bifurcation analysis and stability design for aircraft longitudinal motion are investigated when the nonlinearity in flight dynamics takes place severely at high angle of attack regime. To predict the special nonlinear flight phenomena, bifurcation theory and continuation method are employed to systematically analyze the nonlinear motions. With the refinement of the flight dynamics for F-8 Crusader longitudinal motion, a framework is derived to identify the stationary bifurcation and dynamic bifurcation for high-dimensional system. Case study shows that the F-8longitudinal motion undergoes saddle node bifurcation, Hopf bifurcation, Zero-Hopf bifurcation and branch point bifurcation under certain conditions. Moreover, the Hopf bifurcation renders series of multiple frequency pitch oscillation phenomena, which deteriorate the flight control stability severely. To relieve the adverse effects of these phenomena, a stabilization control based on gain scheduling and polynomial fitting for F-8 longitudinal motion is presented to enlarge the flight envelope. Simulation results validate the effectiveness of the proposed scheme.     

分布式仿真系统实体节点分配问题实时求解算法

分布式仿真系统中,如何使计算节点彼此间通信量尽可能小,是实体节点分配问题研究的内容。针对该问题提出一种基于规则的启发式两阶段实时求解算法。第一阶段构建最小期望事件数量的目标分配模型并进行求解,即根据连通图理论将原问题分解为多个子问题,结合缓存、分治和过滤优选策略,设计递归算法求解子问题,最后得到覆盖所有实体的事件最小集。第二阶段实现分箱算法,将最小集中单个事件关联的实体尽量分配至相同计算节点,最终得到实体节点分配关系。实际应用表明,相比常见的顺序分配策略,该算法能显著减小分布式仿真系统的跨节点网络通信,从而提升仿真效率。该算法还能在秒级耗时生成分配方案,特别适用于包含大量实体的复杂场景分布式仿真。     

Vulnerability analysis for airport networks based on fuzzy soft sets: From the structural and functional perspective

Recently,much attention has been paid to the reliability and vulnerability of critical infrastructure.In air traffic systems,the vulnerability analysis for airport networks can be used to guide air traffic administrations in their prioritization of the maintenance and repair of airports,as well as to avoid unnecessary disturbances in the planning of flight schedules.In this paper,the evaluation methods of airport importance and network efficiency are established.Firstly,the evaluation indices of airport importance are proposed from both the topological and functional perspectives.The topological characteristics come from the structure of airport network and the functional features stem from the traffic flow distribution taking place inside the network.Secondly,an integrated evaluation method based on fuzzy soft set theory is proposed to identify the key airports,which can fuse together importance indices over different time intervals.Thirdly,an airport network efficiency method is established for the purpose of assessing the accuracy of the evaluation method.Finally,empirical studies using real traffic data of US and China’s airport networks show that the evaluation method proposed in this paper is the most accurate.The vulnerability of US and China’s airport networks is compared.The similarities and differences between airport geography distribution and airport importance distribution are discussed here and the dynamics of airport importance is studied as well.