Quantitative assessment and visualization of flight risk induced by coupled multi-factor under icing conditions

Aircraft icing has been proven to be one of the most serious threats to flight safety. During the analysis of flight risk under icing conditions, quantitative assessment and visualization of flight risk are quite essential as they provide safe manipulation strategies in intricate conditions. However, they are rarely studied. Since the icing flight accidents are the result of the coupling of multiple unfavorable factors, in present study, we have proposed a method to quantitatively assess flight risk induced by multi-factor coupling under icing conditions by Monte-Carlo simulation and multivariate extreme value theory. The results demonstrate that the flight risk probability increases with the rise of unfavorable factors. Besides, a flight risk visualization method named flight safety window has been presented to build the flight risk distribution cloud maps in different complex conditions. The cloud maps show that the icing would give rise to atrophy of the safety scope, and the consequence would be even more severe when coupled with other more unfavorable factors. The proposed methods in this study would be useful in flight risk analysis under icing conditions and can enhance the pilot's situational awareness in selecting correct strategies within the safety zone to avoid unsafe manipulation.     

ADS-B监视报文参数统计及其所需性能

基于广播式自动相关监视（ADS-B）报文的位置导航不确定性指标（NUC_P）的监视质量备受关注。针对位置导航不确定性参数好、监视质量却不高的问题，深入研究广播式自动相关监视报文数据项及其与基于性能的通信与监视的相关性。在充分考虑通信导航监视相关性及全球卫星导航系统（GNSS）广域增强等因素基础上，推导、构建了监视所需性能估计模型，并给予合理简化。在测试空域利用2个具有运行资质的生产商ADS-B接收站，连续采集近2亿条ADS-B报文，统计分析报文各信息项的状态参数，并应用到所需性能估计模型评估计算这两个ADS-B站的所需监视性能。此外还将参考文献报文参数代入模型评估所需性能。结果显示，当考虑报文各信息项统计状态及具备广域增强服务支撑时，ADS-B所需监视性能参数估计值未达到99.9%要求。若缺乏广域增强服务及相关性因素等，系统所需性能与国际民航组织（ICAO）监视要求的差距则更大。     

利用地月间空间站的载人登月飞行模式分析

为提高空间站利用率，降低载人登月任务成本，有效开发地月空间，研究了基于地月空间不同轨道空间站的载人登月飞行模式。首先对比直接往返登月飞行模式，对基于空间站的载人登月飞行模式进行任务分析，通过空间站将载人登月任务解耦为载人天地往返任务和登月任务两部分；其次通过轨道设计和稳定性分析提出考虑登月任务需求的地月间空间站可运行轨道和停泊点；最后建立一套飞行模式评价模型，从速度增量需求、飞行时间、空间环境、登月任务窗口、测控条件、交会对接技术难度、后续任务支持性和任务可靠性方面对6种不同位置空间站的登月飞行模式进行分析和定量评价。评价结果表明基于L2点Halo轨道空间站的载人登月飞行模式为更优飞行模式。     

一种未来大型天地往返运输系统平台气动方案

针对未来低运行成本、可直接水平起降、重复使用的大型天地往返运输系统平台飞行器研制所需重点解决的全速域气动力性能需求与气动热防护匹配等难题，分析了典型航天飞机方案所存在的能量运行缺陷等主要问题及可能的改善方案。基于放宽气动热防护设计、涡轮/冲压/火箭发动机三动力组合、嵌套式旋转机翼全速域变体、在爬升阶段将飞行动能转化为高度势能以及再入阶段“跳跃式”盘旋减速飞行轨迹控制等设计思想，从能量损失速率控制和回收利用等角度出发，开展了一种新型大型天地往返运输系统平台气动布局概念设计研究。全速域气动力/热性能工程估算以及内/外流整体气动效能初步分析结果表明，该方案可有效满足整个飞行包线内的升重平衡需求，相比航天飞机方案具有显著的整体气动效能优势，值得进一步开展深入研究。     

A CFD-based numerical virtual flight simulator and its application in control law design of a maneuverable missile model

A CFD-based Numerical Virtual Flight (NVF) simulator is presented, which integrates an unsteady flow solver on moving hybrid grids, a Rigid-Body Dynamics (RBD) solver and a module of the Flight Control System (FCS). A technique of dynamic hybrid grids is developed to control the active control surfaces with body morphing, with a technique of parallel unstructured dynamic overlapping grids generating proper moving grids over the deflecting control surfaces (e.g. the afterbody rudders of a missile). For the flow/kinematic coupled problems, the 6 Degree-Of-Freedom (DOF) equations are solved by an explicit or implicit method coupled with the URANS CFD solver. The module of the control law is explicitly coupled into the NVF simulator and then improved by the simulation of the pitching maneuver process of a maneuverable missile model. A nonlinear dynamic inversion method is then implemented to design the control law for the pitching process of the maneuverable missile model. Simulations and analysis of the pitching maneuver process are carried out by the NVF simulator to improve the flight control law. Higher control response performance is obtained by adjusting the gain factors and adding an integrator into the control loop.     

民用飞机飞控系统副翼下垂浅析

在飞机起飞或着陆飞行阶段,当缝翼伸出襟翼放下时,副翼也随之对称地下偏一定偏度,这就增加了机翼的弯度,提高了机翼升力。从而减少了飞机起飞／着陆的速度和场长,改善了起飞和着陆性能。通过介绍X飞机与Y飞机的副翼下垂功能的历史发展、功能原理与功能实现,较详细地分析了副翼下垂功能的实现方式。     

民机新一代驾驶舱显示技术

在研究最新大型民用客机驾驶舱显示技术及平视显示器、电子飞行包、视景增强、合成视景等一系列新兴在研技术基础上,提出新一代驾驶舱显示技术的构想。新一代驾驶舱显示技术将以形象化的信息表达能力为基础,显示更丰富的周围环境,以达到降低飞行员工作量及提高飞行员情景意识和态势感知能力的目的。     

Geostationary orbit determination using SATRE

A new strategy of precise orbit determination (POD) for GEO (Geostationary Earth Orbit) satellite using SATRE (SAtellite Time and Ranging Equipment) is presented. Two observation modes are proposed and different channels of the same instruments are used to construct different observation modes, one mode receiving time signals from their own station and the other mode receiving time signals from each other for two stations called pairs of combined observations. Using data from such a tracking network in China, the results for both modes are compared. The precise orbit determination for the Sino-1 satellite using the data from 6 June 2005 to 13 June 2005 has been carried out in this work. The RMS (Root-Mean-Square) of observing residuals for 3-day solutions with the former mode is better than 9.1 cm. The RMS of observing residuals for 3-day solutions with the latter mode is better than 4.8 cm, much better than the former mode. Orbital overlapping (3-day orbit solution with 1-day orbit overlap) tests show that the RMS of the orbit difference for the former mode is 0.16 m in the radial direction, 0.53 m in the along-track direction, 0.97 m in the cross-track direction and 1.12 m in the 3-dimension position and the RMS of the orbit difference for the latter mode is 0.36 m in the radial direction, 0.89 m in the along-track direction, 1.18 m in the cross-track direction and 1.52 m in the 3-dimension position, almost the same as the former mode. All the experiments indicate that a meter-level accuracy of orbit determination for geostationary satellite is achievable.     

九寨机场航务代理工作浅谈

在分析了九寨机场的气象特点以及环境因素对航空器造成的影响的基础上,就如何做好九寨机场的航务代理工作提出了合理建议和措施,这对提高航班正常率非常重要.     

双基地天基雷达功率孔径积分析

功率孔径积是制约天基雷达系统性能的一项重要因素.从接收功率的角度给出双基地天基雷达搜索方程的详细理论推导,并通过与单基地天基雷达搜索方程的比较得出一个重要的结论--双基地天基雷达的功率孔径积在面积覆盖率和目标散射系数固定条件下,只与接收距离有关而与发射距离无关.进一步证明了地球同步卫星-飞艇双基地天基雷达系统需要更低的...