MEMS Electronically Steerable Antennas for Fire Control Radars

Large apertures are of great benefit to applications that are prime powered limited as is found on aerostat and other airborne platforms. Electronically scanned array antennas are often proposed for these applications. However, increasing the aperture area with conventional array technology is met with prohibitive cost, weight, and prime power increases because of the dense spacing of phase shifters and/or active T/R modules. This discusses the recent development of RF MEMS (Microelectromechanical System) switch technology and the use of these switches in a Radanttrade lens configuration for arrays of approximately 10 m² at X-band. A proof-of-concept 0.4 m² MEMS Electronically Steerable Antenna (ESA) containing 25,000 MEMS switches has been successfully designed, fabricated, and tested. The 0.4 m² MEMS ESA was then integrated with an AN/APG-67 radar system to form the MEMS Demonstration Radar System. The MEMS Demonstration Radar System successfully detected both airborne and ground moving targets during a series of extensive radar demonstrations. This is believed to be the first large scale employment of MEMS switches in a scanning antenna and radar system. The low-cost, lightweight, and low power technology demonstrated can enable weight and power constrained platforms with electronic steering.     

Benefits and challenges of Integrated Sensor Systems

Projection of avionics system costs shows unacceptable escalation as a percentage of flyaway cost. Time sharing of RF modules between Radar, EW and CNI offers savings. The Air Forces' PAVE PACE program defined the benefits and initial architecture approaches. From this, an optimum Integrated Sensor System (ISS) design was defined that reduces the life cycle cost of the fleet of vehicles using the common modules. The ISS program will design, build and test modules to prove the approach. Challenges to overcome include system complexity, real time control, test and calibration, and diagnostics. The most stressing requirements were determined by analyzing requirements for Radar, EW and CNI. Open interface specifications and module partitioning were developed that can meet all the requirements     

Aircraft VSCF generator expert system

VSCF (variable-speed constant-frequency) electrical systems are designed using standard modules to reduce the manufacturing cost and improve the product quality and services. An expert system that automatically configures the modules required for a particular application is described. It is a rule-based synthesis system with a domain that encompasses the matrix of standard modules. The module functions include electrical generation, conversion, the control. All the modules must be placed in a proper package to fit the space available inside the particular airplane. The configuration system is built by using a rule-based expert system development tool, OPS5, in a VAX 11/750 computer. It has the domain-specific knowledge necessary to configure the generators embedded in its rulebased and exhibits expertise to place the modules in the proper arrangement based on customer specifications and design criteria. The system can also help the engineers and salespersons to determine the configuration at quotation time and to point out any new design which is required     

Two low-cost phased arrays

In a phased array antenna, the phase shifters (or T/R modules in an active aperture phased array) with their beam-steering control circuitry along with the feed network account for the major hardware cost. This paper presents two antenna array configurations that use simpler feed, simpler phase-shifting and simpler beam-steering control circuitry for realizing low-cost phased arrays. Both are lens configurations. The first one uses a Radant lens, which provides a medium that is loaded with diodes and provides the needed phase shift by switching the diodes on and off. The other configuration employs a ferroelectric dielectric material whose dielectric constant can be varied with an applied DC bias voltage. It is shown that the ferroelectric lens may have further advantages of smaller thickness, simpler beam-steering controls and lower cost     

民用飞机空调系统仿真分析

建立了系统主要部件数学模型,利用Matlab/Simulink平台开发了系统部件仿真模块、驾驶舱/客舱热载荷等模块,并搭建了某民用飞机空调系统仿真模型.在某国产商用飞机空调系统上加装了测试装置,并进行试验测试.通过仿真分析及试验结果比对发现,参数误差在2%以内,由此表明:建立的仿真模块具有较高的精度,提出的建模方法合理有效,对飞机空调系统设计、优化及适航符合性验证具有较高的使用价值.      

基于仿真技术的空调系统冲压空气能耗研究

简要介绍了开展民用飞机空调系统仿真分析及研究的重要意义和空调系统工作原理。建立了民用飞机空调系统主要部件的数学模型,开发了系统部件仿真模块及驾驶舱/客舱热载荷模块等,用搭建的部件模块组建了某民用飞机空调系统仿真模型,完成了仿真计算算例。对仿真算例进行试验验证以修正仿真模型,应用修正的仿真模型预测民用飞机整个飞行剖面内空调系统的冲压空气流量,同时采用标准计算方法评估空调系统冲压空气能耗,为空调系统的冲压设计提供依据,对飞机空调系统设计、优化及适航符合性验证具有重要的参考意义。     

虚拟现实技术在某民机培训中的应用

虚拟现实技术是20世纪兴起的一项综合性技术，随着科学技术的发展，该技术得到了快速的发展及广泛的应用。针对传统民机培训中存在的课程枯燥、培训效率低下以及成本高昂等问题，虚拟现实技术被逐步应用到民机培训中，并得到长足的发展。对某民机培训中心搭建的虚拟现实培训系统进行了介绍，包括大型沉浸式、头盔式及桌面式三种虚拟现实培训平台，详细介绍了以上三种虚拟现实培训系统的软、硬件组成，包括显示系统、交互设备及开发软件等；并对三种虚拟现实培训系统的优缺点进行了简要总结。针对培训内容在开发过程中存在的复杂、繁琐问题，介绍了基于Unity 3D开发引擎且适用于三种虚拟现实培训系统的无编程课件开发流程。最后对虚拟现实技术在民机培训中的发展方向进行了展望。     

Optimal number of phased array faces and signal processors for horizon surveillance

The problem of the optimal number of phased array faces for performing 360/spl deg/ horizon surveillance is considered. Assuming the detection performance is the same in all beam positions and the total number of T/R modules is constant, it is shown that the optimal number of array faces is three. This is true whether the arrays are operating simultaneously or sequentially. A parametric analysis is performed between the number of array faces operating simultaneously and the associated cost of simultaneous operation in terms of the size of the array.     

民用飞机直接维修成本分配模型研究

降低民用飞机直接维修成本是提高飞机经济性、增强市场竞争力的重要途径。以民用飞机研制阶段在很大程度上决定其维修成本的高低为背景,在分析相关文献研究成果的基础上,构建可反映民用飞机成本特性的设计参数结构层次图,基于 TOPSIS-灰色关联法计算类似机型的相对相似度,进行民用飞机直接维修成本分配;将类似机型典型系统直接维修成...     

余度伺服作动系统可靠性分析

可靠性是飞机设计的重要指标,现代民用飞机电传操纵系统的伺服作动系统普遍采用余度技术,传统的可靠性分析方法无法描述其动态过程。针对主备结构和三余度结构2种不同的民用飞机伺服作动系统方案,应用马尔可夫过程对其分别建立了可靠性模型,并仿真分析比较了两者的可靠性及故障覆盖率对系统可靠性的影响,对实际中系统方案的选择提供了理论依据。     

MEMS tomographic imaging system simulation

This describes a simulation architecture used to simulate an ultra-narrowband radar tomographic imaging (UNBRaTI) system. The work is being performed at Rochester Institute of Technology. This lays the groundwork for an effort to develop a systems level approach for the simulation and analysis of an UNBRaTI system using traditional radio frequency (RF) components as well as micro-electro-mechanical systems (MEMS)-hased components. The utility of the approach is its ability to apply sound systems engineering principles and techniques to compare and contrast traditional RF components with MEMS-based components and their effects on system level performance. The simulation has been architected for ease of scalability in order to analyze basic to complex system configurations.     

基于动态故障树分析的民用飞机辅助动力装置系统安全性评估

在民用航空工业领域,传统的故障树分析方法广泛运用于系统安全性评估。然而,包含系统/子系统运行的时序阐述以及备份、冗余表达在内的动态特性不能通过传统故障树呈现。另一方面,民用飞机辅助动力装置(APU)经常作为一个冗余系统运作,因而其行为可以通过运用动态故障树进行适当的描述。所以APU的这种特性激发了动态故障树分析在APU系统安全性评估上应用的关注。首先介绍了两种动态门(优先与门和冷备件门),其定量计算通过施用马尔可夫模型来呈现;然后分别通过传统故障树以及动态故障树分析了APU系统安全性评估的两个典型案例;最后进行了两种故障树分析(FTA)的比较,其结果显示出通过合理的应用,动态故障树(DFTA)方法达到了对于真实情况来说相当高的精度,并且对指数分布函数施用二阶近似后,其运算成本也是可以接受的。     

Low-cost TDRSS communications for NASA's long duration balloonproject

A transponder and RF ground support equipment that are making tracking and data relay satellite system (TDRSS) communications available to lower budget NASA projects are discussed. The Goddard Space Flight Center (GSFC)/Wallops Flight Facility's long duration balloon project (LDBP) will be the first to take advantage of this TDRSS user hardware for communications through the TDRSS S-band multiple access system during their around-the-world scientific balloon flight campaigns. The transponder is one tenth the cost of the current generation space-qualified transponder, and the TDRSS user RF test set (TURFTS) is less than one half the cost of the currently available transponder test equipment     

面向飞机维修过程的数字支援系统研究

在研究欧盟的民用飞机维修方式研究计划(TATEM)的基础上,分析飞机维修过程的主要因素并建立了飞机维修过程的数学模型。通过模糊数学知识实现对数字支援系统拟采用的技术手段对飞机维修工程促进作用的评价,详细设计了数字支援系统的主要功能模块,并用于指导系统软件的开发。面向飞机维修过程的数字支援系统的研究与开发对于其他复杂设备的维修过程数字化建设有着重要的借鉴意义。     

民机项目风险量化方法及应用的研究

民机项目中大量新技术的应用和众多复杂系统的集成,增加了项目进度、费用和性能的不确定性,在众多环节中风险因子要素层出不穷。为了保障民机项目过程的顺利进行,降低项目的风险水平,必须建立先进的风险管理体系。针对民机项目风险管理体系中的风险量化难题,深入挖掘风险量化手段本身的技术内涵,结合民机项目的特点,引入了模糊层次分析法的风险量化方法,并通过民机项目风险实例进行验证。     

基于车载平台的飞行管理系统DR/GPS 导航试验验证

飞行管理系统是民用飞机的关键航空电子系统。飞行管理系统制造商有责任对飞行管理系统开展大 量的试验以验证飞行管理系统功能和性能的符合性。考虑数字验证的局限性和飞行试验验证的巨大代价,本文 利用车载平台开展飞行管理系统综合导航功能的验证,试验结果表明设计的飞行管理系统DR/GPS 导航方法能 够满足95% 的飞行时间水平方向达到0.1 海里的导航精度要求,为实际的飞行测试提供了试验数据参考。     

民用飞机甚高频通信天线设计

作为民用飞机甚高频(Very High Frequency,以下简称VHF)通信系统的重要组成部分,VHF通信天线不仅辐射和接收电磁波,还要进行能量转换。VHF通信天线的设计直接影响通信中射频能量的分布,进而影响通信质量和飞行安全。简要介绍了VHF通信系统,并在给出VHF通信天线设计要求的基础上,通过工程实例分析了VHF通信天线的设计过程,最后总结了VHF通信天线设计的特点。     

组合GPS和GLONASS在民航中应用的研究

研究了ＧＰＳ和ＧＬＯＮＡＳＳ在民用航空中的应用前景。分析了组合ＧＰＳ和ＧＬＯＮＡＳＳ所具备的可用性、精确性和完整性潜力。组合ＧＰＳ／ＧＬＯＮＡＳＳ在我国民航中具有重要的技术与战略意义。提出了一种集成１２通道ＧＰＳ／ＧＬＯＮＡＳＳ接收机的结构与实现。射频前端部分采用３级变频将ＧＰＳ和ＧＬＯＮＡＳＳ信号变至中频并采样为同相与正交样本。数字处理部分对各样本加以积累与处理,解调卫星的导航电文。在导航解算中结合了ＷＧＳ－８４和ＰＺ－９０坐标系之间的转换。     

民用飞机系统需求确认研究

本文从系统工程的角度和民机设计的要求出发,主要讨论了民用飞机系统开发过程中需求的确认工作.需求相关工作是系统设计的一个起点,对于后续的工作将会产生巨大的影响.为了降低风险和研发成本,在设计之初首先需要做好系统的需求确认工作,保证需求的正确性和完备性,这样才能保证设计实现的正确性,最终实现项目的成功.本文从适航性的角度出发,着重描述了系统需求确认工作的流程和相关的确认方法.希望通过这篇文章能够为高度综合、复杂的飞机系统设计研制提供必要的支持     

SiO_2-C复合气凝胶的制备及其结构

以间苯二酚(R)和甲醛(F)为碳源,以3-胺丙基三乙氧基硅烷(APTES)为硅源,一步溶胶一凝胶法简单快捷地合成了SiO_2-RF复合气凝胶,高温碳化后得到SiO_2-C复合气凝胶,并用扫描电镜、比表面分析仪对所得样品的结构进行了研究,并讨论了不同投料比对气凝胶结构的影响.结果表明碳化前,投料比APTES/R=1时,所得气凝胶具有最大的比表面积(S_(BET)=606.1 m~2/g),碳化后,由于体积收缩和酚醛热解产生新孔隙双重因素的影响,投料比AFTES/R=1/2时样品的比表面积达到最大(S_(BET)=704.2 m~2/g).