Analysis of airborne GPS multipath effects using high-fidelity EM models

Airborne GPS systems are being upgraded to provide sufficient positioning accuracy to support automatic landing operations in low visibility conditions. This is made possible by differential GPS (DGPS), in which the errors common to the airborne receiver and ground station are removed by knowledge of the latter's precise location. However, errors specific to the airborne system remain, of which the dominant components are receiver noise and multipath. To support the assessment of the integrity of the signal in space, these residual errors are incorporated in a statistically based error model, designated as the "standard model." The standard model is defined as the standard deviation of a Gaussian distribution that overbounds the residual pseudo-range (PR) error. It relates the standard deviation of the overbounding distribution to the elevation angle of the satellite relative to the local level coordinate system. The international community is currently developing improved standards to enable DGPS systems to support landings in the worst visibility conditions (i.e., CAT III). As a part of this development, the standard model for multipath is being re-evaluated and an improved model is sought. In order to better characterize the residual multipath errors, tools for accurate calculation of the airframe scattering effects are needed. Development of such tools is the subject of this paper. A new method for accurately computing pseudo-range error, based on the use of high-fidelity EM models, is described. This approach provides new insight into the mechanisms causing multipath error.     

基于多目标规划理论的单跑道机场容量分配

通过分析机场跑道实际运行过程,建立了估计单跑道机场的容量模型并且利用该模型对跑道进行了容量评估。在考虑起降比例、流量平衡、停机位数量、跑道起降容量等限制条件的基础上,构造了多目标规划模型。通过改变预期目标的优先级别对3种跑道利用情况进行了容量分配,分配结果均实现了预期控制目标,仿真证明多目标规划方法是空中交通辅助决策的有效工具。     

Autonomous Landing Guidance Systems

All weather tactical aircraft recovery and high sortie generation rates from forward, possibly battle damaged landing areas will reqire autonomous landing guidance systems which are independent of ground-based cooperative aids. A recently completed study has examined the operational requirements and assessed current and near term technology for an answer to this need. The Landing Systems Requirements/Synthesis Study has defined the Pilot/vehicle Interface and imaging sensor suite required, based on the concept of augmenting pilot forward vision with sensor imagery and guidance symbology on a HUD during low visibility landings. Image processing technology was also assessed for potential enhancement of the information presented to the pilot. This paper summarizes the final report of the Study, which is in publication.     

Hybridizing contemporary glide slopes to provide vertical guidancefor GPS approaches

Vertical guidance for an instrument approach to landing during conditions of reduced visibility is a crucial element with respect to safety of flight. It is noteworthy that this vertical component-to be most useful and safe-must desirably provide the pilot with no more than several feet of uncertainty. Unfortunately, with GPS the vertical portion of the position information supplied the pilot by GPS signals is the least precise because of geometries involved. Augmentation for enhancement of accuracy is quite important and the assertion is that it is necessary for totally safe vertical guidance. Evidence from approximately 60 years of experience with electronic landing systems serving the public is that there has been no aircraft accident due to a defective vertical guidance signal. Visibilities as low as 600 feet horizontally can exist at certain airports and landings can still be accomplished. These landings, while not common, are being accomplished flawlessly by contemporary aircraft and equipment. Many aspects of the contemporary UHF glide slope have been studied during its half-century of use. This paper reports on advances, some of them quite recent, that make it realistic to claim that a glide slope can be sited for Category I operation at any runway that meets the physical requirements for this type of operation. For the UHF glide slope, siting imperfections are accommodated by using one of five available types of contemporary glide slope systems or derivatives thereof. This paper reviews how accommodations are achieved in practical cases. Results from earlier tests are identified which show hybridizing of UHF glide slopes and GPS can be used to provide good approach guidance to aircraft making fully automatic approaches to touchdown     

用于观测导航的新方法——地标图象的计算机识别

本文提出一种利用带有地面目标精细结构的雷达图象或用其它方法得到的地面目标的图象进行定位的方法。它避免了利用地标导航因能见度带来的限制,并可应用于远程导航。在对图象的识别上,采用了基于R变挟的R描绘子来进行分析,并考虑了用于地标识别时的特殊问题。     

大型客机CATIII级精密进近着陆设备的适航性要求

本文主要研究CATIII运行的适航性，首先介绍了适航性的基本概念，同时指出运输类飞机有关设备、系统及安装的适航标准，然后根据进场、着陆和滑跑三个飞行阶段，从性能、完好性、有效性三个方面提出系统适航性的具体要求，此外还包括某些自动飞行控制系统的适航要求，最后简述有关使用和维修方面的持续适航性。     

Letting thoughts take wing

Recent developments in neuroelectronics are applied to aviation and airplane flight control instruments. Electromyographic control has been applied to flight simulations using the autopilot interface in order to use gestures to give bank and pitch commands to the autopilot. In other demonstrations, direct rate control was used to perform repeated successful landings and the damage-adaptive capability of inner-loop neural and propulsion-based controls was utilized.     

基于Otsu和FMM方法的风洞试验图像修复

各种光学测试技术在风洞试验中应用越来越广泛，图像中的破损或无关信息均会影响数据的处理和分析。以存在缺陷的风洞纹影图像为例，对数字图像修复技术进行了研究。根据缺陷离散分布、大小及形状各异，核心区域的灰度值较低以及边缘处灰度梯度变化较大等特点，将图像修复流程设计为确定待处理区域、缺陷识别和缺陷修复等3个步骤。前2个步骤使用Otsu算法进行图像的分割处理，然后使用快速行进方法（FMM）完成缺陷修复。经处理，纹影图像的缺陷被自动识别，并得到了减少或削弱，而且修复的信息客观合理。该方法可推广至其他光学测试技术的图像修复。     

图像配准关键技术综述

图像采集设备的快速发展带来了图像种类和数量的迅速增加,图像拼接、融合等视觉系统提高了对图像配准的技术需求。图像配准利用原始图像数据或图像特征信息对输入图像的重叠区域进行变换和对齐,是为后续图像拼接、图像融合等图像处理任务提供操作基准的核心技术,是当前计算机视觉领域的热点研究问题。首先介绍了图像配准技术的主要应用领域及重大发展前景,然后说明了图像配准技术的基本框架和技术难点,详细阐述了基于特征以及基于区域的图像配准技术的实现算法及关键技术,分析了不同配准算法的优缺点及适用性,并对图像配准技术的发展前景进行了讨论和展望。     

面向军事应用的航空人工智能技术架构研究

通过全面梳理国内外面向军事应用的航空装备智能化发展现状,紧密围绕未来智能化空中作战的任务场景,给出航空军用人工智能技术的概念和内涵,并依据智能系统信息运行模型,提出不同运行层级的航空装备智能升级的途径和方法。在此基础上,形成包含基础使能、关键技术群、智能系统、运行层级的航空人工智能技术架构,对关键技术群按面向运行层级、面向功能需求、面向基础使能进行分析,得到重点技术发展方向,并给出提升我国航空装备智能化水平的具体措施建议,为制定相关航空人工智能技术规划提供参考。     

航空橡胶密封件力学与密封性能检测技术

介绍了航空橡胶密封件的力学、泄漏、损伤、接触变形等特性的无损检测技术及应用情况。其中,橡胶密封件泄漏压差测量方法,用于获得不同压差下的气体泄漏率;橡胶密封件接触应力超声检测技术,实现了橡胶密封接触应力的准确测量;橡胶密封件损伤与泄漏的红外热成像测试技术,可以得到泄漏点的定位与泄漏量的精确测量;橡胶密封件接触变形数字图像相关技术,获得了织物接触界面变形场与应力场的演化规律等。同时,对航空橡胶密封件的非接触测量技术进行了展望。     

Corrosion and aging of organic aviation coatings: A review

Organic anticorrosive aviation coatings are an effective guarantee for aviation structure,since aircraft corrosion can lead to great economic losses. Whether it is during ground parking or air cruises, organic aviation coatings are important barriers to the corrosion of aviation structure.With the vigorous development of the aviation industry, organic aviation coatings continue to meet the challenges of diverse, complex, and harsh service environments. This review analyzes and summarizes the res...     

武装直升机红外成像仿真

虚拟仿真以其低成本、短周期、高质量的特点,逐渐成为复杂环境下红外成像制导武器设计分析、验证和评估的主要手段之一。以某武装直升机目标为对象,首先利用基于航空发动机物理模型的方法,通过全尺寸几何建模、计算蒙皮、尾喷和羽烟等主要红外辐射源的流场和温度场,利用灰度等级描述红外辐射信息,生成不同视向角下的近场红外辐射亮度显示,并存储形成数据库。然后根据具体使用时的条件从数据库中调用,按照距离进行大气衰减,最终形成视点处的红外辐射亮度显示。实验结果证明,算法生成的武装直升机红外图像真实感强,实时性好,可用于红外成像制导导弹仿真和夜航模拟训练系统的红外视景显示,具有一定的军事参考价值。     

二维图像拼接技术研究综述

图像拼接是指将具有重叠区域的小视角、低分辨率的多张图像，经过相应的图像配准与融合算法，拼接成一张具有高分辨率、宽视角的全景图像。针对二维图像拼接方法，综述了将二维图像拼接技术应用于图像处理领域的最新研究进展，重点介绍和总结了图像配准方法和图像融合方法。其中，图像配准方法涵盖了基于SIFT、SURF和Harris点特征的提取方法。分析了各种算法的主要进展、典型算法的原理和优缺点以及国内外研究发展现状。最后，通过各种方法研究与应用情况推测，展望了未来图像拼接技术的发展趋势。     

夜间成像光测数字图像增强技术研究

分析夜间成像的光测数字图像灰度范围、对比度和信息量等主要特点,为图像增强的策略选择和效果评价提供依据。针对夜间成像光测数字图像灰度范围较窄等特点,提出局部灰度修正的增强方法适当增强图像对比度,又避免细节损失,同时,利用拉普拉斯锐化突出目标轮廓和边缘,并利用人眼对彩色敏感的特点,采用伪彩色增强提高对图像中模糊目标的分辨能力。通过上述3种增强技术,提高了对夜间成像暗图像的目标识别能力,有利于后续判读处理。     

OGSRN: Optical-guided super-resolution network for SAR image

Although Convolutional Neural Networks(CNNs) have significantly improved the development of image Super-Resolution(SR) technology in recent years, the existing SR methods for SAR image with large scale factors have rarely been studied due to technical difficulty. A more efficient method is to obtain comprehensive information to guide the SAR image reconstruction.Indeed, the co-registered High-Resolution(HR) optical image has been successfully applied to enhance the quality of SAR image due to it...     

航空事业发展中的飞行试验研究技术

本文根据国内、外航空事业发展的实践,简要地阐述了飞行试验研究技术在航空事业发展中的地位、作用和特点以及我国飞行试验研究技术的现状和差距,并提出了一些发展建议,供制订有关航空技术发展政策和规划时参考。     

航空武器装备顶层论证技术发展现状与趋势

航空武器装备顶层论证是航空武器装备论证的重要内容,是航空武器装备发展的顶层设计与型号发展的先期论证。开展航空武器装备顶层论证,是实现航空武器装备体系对抗的需要,也是航空武器装备由跟踪发展向自主创新跨越的需要。分析了航空武器装备顶层论证技术面临的挑战,回顾了航空武器装备顶层论证技术从产生到逐步完善的发展历程,剖析了航空武器装备顶层论证当前面临的技术难点与可能的应对策略,探讨了航空武器装备顶层论证技术当前及今后一个时期的研究重点与发展趋势。     

民用飞机机载跑道入侵预警系统仿真验证

民用飞机在低能见度的机场跑道滑行时,存在发生跑道入侵的风险。国内外民航史记载了数次因跑道入侵事件导致的飞机在机场地面相撞而机毁人亡的严重事故。近年来,越来越多的人选择飞机作为长途出行的交通工具,使得全球大型国际机场的年吞吐量剧增,导致跑道入侵事件时有发生。各国民用航空管理组织对跑道入侵事件的关注度持续上升,航空公司需要在机上安装一套地面避撞系统,来避免跑道入侵事件的发生。本验证项目基于某大型机场的动态地图建立了一个机载跑道入侵预警系统原型,建立了飞机在机场滑行的平面四向运动模型,设定了不同安全等级的跑道入侵预警算法,定义了多种飞机跑道入侵场景,最终在MATLAB/Simulink和FlightGear中进行二维平面仿真和三维立体仿真,验证了系统解决方案的有效性和算法的正确性。