时变热辐射环境下高温合金蜂窝板三维热变形测量

轻质、高强和隔热性能优良的蜂窝合金板结构已广泛用于航空航天领域,其在模拟瞬态气动热环境下的热变形是高速飞行器热防护结构设计的重要参数之一.首先,用自行研制的红外辐射瞬态气动热实验模拟系统模拟与其服役环境类似的时变热辐射环境,用新型"主动成像"三维数字图像相关(3D-DIC)测量方法对高温合金蜂窝板结构试件在时变热辐射环境下不同时刻的三维热变形进行了测量.其次,为保证三维数字图像相关测量方法能有效实施,提出一种制作稳定的大面积高温散斑新方法,该方法制作的高温散斑能在整个实验过程中保持稳定,可作为高温变形的有效载体.最后,用Hoff等效刚度理论计算高温合金蜂窝板在稳态时的最大翘曲位移.研究结果表明:210 mm×210 mm的高温合金蜂窝板在单侧面辐射加热条件下其面内变形为均匀热变形,而离面变形为轴对称的翘曲变形,在900℃时其最大离面翘曲位移约为1.6 mm;Hoff等效刚度理论计算结果与实验结果相吻合.      

CCAR23部飞机HIRF防护适航验证方法研究

民用飞机为获得在高强辐射场环境中的运营许可,必须按照适航当局发布的高能电磁辐射场( HIRF )防护相关适航条款进行防护设计和适航验证。当前确定航空器内部 HIRF 环境主要通过试验方法和相似性评估法,具有工作量大、测试成本高等缺点。针对仅有 A 类显示系统的 CCAR23 部飞机首次使用数据推算方法,确定飞机内部 HIRF 环境电平,用于实现整机的 HIRF 防护适航验证;提出一套适用于 CCAR23 部飞机 HIRF防护适航验证的方法,分析该方法的关键技术及可行性。本文所提出的方法已应用于 Y12F 飞机 HIRF 防护适航验证的实际工程,有效降低了整机 HIRF 防护适航验证的复杂程度,节约了整机试验所需的测试成本,提高了试验效率,为民用航空器 HIRF 防护验证提供参考。     

飞行器再入段最优自适应积分滑模姿态控制

针对飞行器再入段的姿态跟踪控制问题,提出了一种最优自适应积分滑模控制(Optimal Adaptive Integral Sliding Mode Control, OAISMC)方法。首先针对飞行器的标称模型设计了基于状态相依黎卡提方程(State Dependent Riccati Equation, SDRE)的姿态控制器,使标称系统的性能满足提出的最优指标。然后,考虑系统的不确定性和外部干扰,在SDRE标称控制器的基础上设计积分滑模姿态控制方法,使系统在满足性能指标要求的同时,对不确定性和干扰具有鲁棒性。进一步采用自适应方法调整切换增益,避免了对复合干扰上界的先验要求,并引入滑模干扰观测器提高系统的性能。最后,仿真结果表明,在考虑外部干扰以及气动系数和大气密度摄动的情况下,本文设计的控制方法不仅能够实现姿态跟踪、满足设计的性能指标,而且具有较好的鲁棒性。     

Study on TT&C resources scheduling technique based on inter-satellite link

The navigation constellation will have the capability of supporting Tracking Telemetry and Command (TT&C) operations by inter-satellite link (ISL). The ISL will become an important solution to reduce the shortage of ground TT&C resources. The problems need to be studied urgently in the field of space TT&C network resources scheduling management are how to determine the availability of ISL and how to allocate TT&C resources of ISL. The performance and scheduling constraints of navigation constellation?s ISL are analyzed, and three utilization strategies of ISL to perform TT&C operations are proposed. The allocation of TT&C resources based on ISL falls into two successive phases. Firstly, master satellite determination equation is established by using 0–1 Programming model based on the availability matrix. Mathematical method is used to solve the equation to determine the master satellite and the topology of ISL. Secondly, Constraint Programming (CP) model is used to describe the ground TT&C resources scheduling problem with special requirements of TT&C operations based on master satellite, and a heuristic algorithm is designed to solve the CP model. The equations and algorithm are verified by simulation examples. The algorithm of TT&C resources scheduling based on ISL has realized the synthesized usage of both the ISL and ground resources on TT&C field. This algorithm can improve TT&C supports of territorial ground TT&C network for global navigation constellation, and provides technical reference for the TT&C mission planning of global constellation by using ISL.     

雷达电子对抗仿真训练系统设计与应用

对雷达电子对抗装备进行仿真模拟训练是一种经济性好、保密性强的先进的训练方法,为此设计了一套基于高层体系结构和建模技术的雷达电子战仿真训练系统。系统以高层体系结构为基本框架,以软件工程技术为核心,并以末制导雷达干扰有源干扰效果评估为例介绍了系统的评估原理。应用实践证明,系统可满足单装备、单平台、小型编组仿真训练要求,有较好的扩展性,具有一定的经济效益和军事效益。     

Is there an abnormal enhancement of atmospheric aerosol before the 2008 Wenchuan earthquake?

There are extensive reports of ionospheric disturbances before the great 2008 Wenchuan earthquake, which are possibly explained by seismogenic electric field hypotheses linked with the aerosols injected in atmosphere. This paper attempts to investigate the possible change of atmospheric aerosol optical depth (AOD) associated with this earthquake by using MODIS data from both Terra and Aqua satellites. The result shows a clear enhancement of AOD along the Longmenshan faults 7 days before the quake, which is 1 day and 4 days earlier than the reported negative and positive ionospheric disturbances, respectively, and is 1 day earlier than or quasi-synchronism with other reported atmospheric anomalies including air temperature, outgoing longwave radiation and relative humidity. Particularly, the spatial distribution of AOD enhancement is very local and it is correlated well with the active faults and surface ruptures. We suggest that this unique enhancement could be associated with the Lithosphere–Atmosphere–Ionosphere coupling process during the preparation of the Wenchuan earthquake.     

低成本飞行试验平台的FADS技术研究

在国内首次利用成熟的低成本火箭弹平台,开展超声速(马赫数>3)飞行试验的嵌入式大气数据传感系统技术研究。针对嵌入式大气数据传感系统的求解算法,测量系统和误差影响等关键技术问题,建立基于神经网络技术的求解算法和设计飞行试验方案,并完成飞行试验和数据分析研究。研究结果表明基于神经网络技术的求解算法具有较好的鲁棒性和较高的求解精度。测量结果与雷达测量结果基本吻合,验证了算法设计;测量结果相对于雷达测量结果,静压平均相对误差约为5.2%,最大相对误差18.8%;马赫数平均相对误差4.2%,最大相对误差14.9%。攻角和侧滑角的测量结果与理论弹道结果变化趋势接近。研究结果可为相关飞行试验技术研究提供参考。     

斜装冗余传感器的分布式导航系统研究

为了满足低成本、高性能惯性导航要求,解决传统单一主惯导系统的成本高、体积大等问题,利用低成本MEMS惯性传感器,采用传感器斜装冗余配置,在最优卡尔曼滤波的基础上提出了一种基于虚拟传感器的最优信息融合技术,简化了测量系统的动态模型,减小计算的同时提高了测量精度。将斜装冗余惯性测量节点安装在载体的不同位置构成基于斜装冗余传感器的分布式导航系统,分析了分布式结构,利用基于虚拟传感器的等效模型,设计了分布式导航系统的测量融合系统。通过仿真试验,校验了基于虚拟传感器的最优信息融合有效地提高了测量精度,基于斜装冗余传感器的分布式导航具有较高的导航精度,同时证明此方法具有一定的抗干扰能力,能够抑制载体局部随机扰动对导航性能的影响。     

基于CGAPIO的航天器编队重构路径规划方法

针对航天器编队重构的路径规划问题,考虑燃料消耗和碰撞概率等约束条件,以及基本鸽群算法存在的问题,提出一种基于混沌初始化和高斯扰动的自适应鸽群(CGAPIO)算法。为了得到多样性和覆盖性更好的鸽群初始值,采用Tent Map混沌模型进行鸽群初始化操作;在地图和指南针算子阶段,为提高全局搜索能力,引入了自适应的权重因子和学习因子更新个体的位置和速度;在地标算子阶段,为避免算法陷入局部最优,将高斯扰动加入到鸽群中心位置。仿真实验结果表明:CGAPIO算法与基本鸽群算法和粒子群算法相比,提高了全局搜索能力,避免了局部最优,规划得到的路径更加平滑,各航天器碰撞概率较低,编队重构消耗的总燃料至少减少了12%。      

Interacting multiple model fixed-lag smoothing algorithm forMarkovian switching systems

We investigate a suboptimal approach to the fixed-lag smoothing problem for Markovian switching systems. A fixed-lag smoothing algorithm is developed by applying the basic Interacting Multiple Model (IMM) approach to a state-augmented system. The computational load is roughly d (the fixed lag) times beyond that of filtering for the original system. In addition, an algorithm that approximates the “fixed-lag” mode probabilities given measurements up to current time is proposed. The algorithm is illustrated via a target tracking simulation example where a significant improvement over the filtering algorithm is achieved at the cost of a time delay (i.e., data up to time k are used to produce the smoothed state estimate at time k-d where the fixed large d>0). the IMM fixed-lag smoothing performance for the given example is comparable to that of an existing IMM fixed-interval smoother. Compared with fixed-interval smoothers, the fixed-lag smoothers can be implemented in real-time with a small delay