UAVSAR：NASA用于科技研究的新型机载SAR系统

NASA的喷气推动实验室目前正在建造可重构的极化L波段合成孔径雷达（SAR），它是专门设计用于为差分干涉测量荻取航空测绘重复航迹SAR数据的。差分干涉仪能够给出关键的变形测量，对于研究地震、火山和其他动态变化现象是很重要的。该系统采用精确的实时GPS和探测器控制飞行管理系统，能够以很高的精度按预设路径飞行。飞行控制系统的期望性能把飞行路径限制在直径为10m的通道内。按其设计，该雷达可在UAV（无人机）上工作，但最初会在NASA的“湾流Ⅲ”上进行验证。这部雷达是全极化的，距离向带宽为80GHz（2m距离分辨率），并支持16km的距离地面条带。天线沿航迹进行电控，以确保天线波束能够独立指向而不用考虑风向和风速。天线所支持的其他特征包括俯仰单脉冲和脉冲一脉冲间的操纵能力，这样可以实现一些新颖的工作模式。系统的额定工作高度为45000英尺（13800米）。该计划是作为NASA地球科学和技术办公室（ESTO）资助的设备孵化器项目（IIP）开始的。     

下一代歼击机雷达的AESA研制模型

提出一项旨在实现下一代歼击机雷达系统而正在进行的研制计划。研究的主要部分是设计、测试和评估一个约有100个有源辐射器的试验样机天线阵列。介绍了阵列结构和测试系统并给出部分初步结果。     

正交各向异性复合材料中裂纹问题的边界元法分析

在基本解的基础上，研究了正交各异性复合材料平面问题边界元法的有关基本问题，包括Ｃ矩阵，Ｇｉｊ矩阵，Ｈｉｊ矩阵和域内应力表达式等，并建立了常值边界单元和线性边界单元的计算公式（适用于各类边值问题）。用建立的公式对正交各向异性板含中心裂纹问题和含圆孔的无限大正交各向异性板问题进行了分析与计算，取得了较好的计算效果。     

高分辨力机载毫米波FM-CW SAR的研发

紧凑的FM—CW（调频-连续波）雷达技术和高分辨力SAR（合成孔径雷达）处理技术的结合将为体积小、重量轻且性价比高的成像雷达的发展铺平道路。然而，在空中观察地球表面这一领域中，将SAR用于FM—CW雷达是比较新颖的。通信传输和雷达国际研究中心（IRCTR）启动了一项关于FM—CW SAR的可行性研究。在该研究项目框架中，开发并测试了一种完全运转的机载FM—CW SAR验证系统。文中综述了地面测试的情况。此外，2004年6月在柏林附近的Strausberg机场进行了一次非常成功的空中试验。本文将介绍这些机载试验的初步结果。     

Human engineering for the space station

Human factor engineering standards and considerations for the International Space Station are reviewed. Factors considered for laboratory and habitation modules, workstations, visual displays, and EVA worksites are discussed.     

The determination of ice composition with instruments on cometary landers

The determination of the composition of materials that make up comets is essential in trying to understand the origin of these primitive objects. The ices especially could be made in several different astrophysical settings including the solar nebula, protosatellite nebulae of the giant planets, and giant molecular clouds that predate the formation of the solar system. Each of these environments makes different ices with different composition. In order to understand the origin of comets, one needs to determine the composition of each of the ice phases. For example, it is of interest to know that comets contain carbon monoxide, CO, but it is much more important to know how much of it is a pure solid phase, is trapped in clathrate hydrates, or is adsorbed on amorphous water ice. In addition, knowledge of the isotopic composition of the constituents will help determine the process that formed the compounds. Finally, it is important to understand the bulk elemental composition of the nucleus. When these data are compared with solar abundances, they put strong constraints on the macro-scale processes that formed the comet. A differential scanning calorimeter (DSC) and an evolved gas analyzer (EGA) will make the necessary association between molecular constituents and their host phases. This combination of instruments takes a small (tens of mg) sample of the comet and slowly heats it in a sealed oven. As the temperature is raised, the DSC precisely measures the heat required, and delivers the gases to the EGA. Changes in the heat required to raise the temperature at a controlled rate are used to identify phase transitions, e.g., crystallization of amorphous ice or melting of hexagonal ice, and the EGA correlates the gases released with the phase transition. The EGA consists of two mass spectrometers run in tandem. The first mass spectrometer is a magnetic-sector ion-momentum analyzer (MAG), and the second is an electrostatic time-of-flight analyzer (TOF). The TOF acts as a detector for the MAG and serves to resolve ambiguities between fragments of similar mass such as CO and N2. Because most of the compounds of interest for the volatile ices are simple, a gas chromatograph is not needed and thus more integration time is available to determine isotopic ratios. A gamma-ray spectrometer (GRS) will determine the elemental abundances of the bulk cometary material by determining the flux of gamma rays produced from the interaction of the cometary material with cosmic ray produced neutrons. Because the gamma rays can penetrate a distance of several tens of centimeters a large volume of material is analyzed. The measured composition is, therefore, much more likely to be representative of the bulk comet than a very small sample that might have lost some of its volatiles. Making these measurements on a lander offers substantial advantages over trying to address similar objectives from an orbiter. For example, an orbiter instrument can determine the presence and isotopic composition of CO in the cometary coma, but only a lander can determine the phase(s) in which the CO is located and separately determine the isotopic composition of each reservoir of CO. The bulk composition of the nucleus might be constrained from separate orbiter analyses of dust and gas in the coma, but the result will be very model dependent, as the ratio of gas to dust in the comet will vary and will not necessarily be equal to the bulk value.     

群钻切削角度的计算与计算机分析

本文建立了用于群钻切削刃切削角度分析、计算的数学模型。这些切削角度是逐点变化的而且对群钻的切削性能有很大的影响。文中借助于钻头的CAD程序、分析了群钻的设计和刃磨参数对钻尖几何形状以及切削角度的影响,并可在设计过程中直观地显示出群钻各切削刃切削角度的变化规律。通过计算机对群钻切削角度的分析计算,可以有助于精确分析群钻的钻削机理并实现群钻钻尖几何形状的优化设计。     

热辐射波长测温法的理论研究

从黑体热辐射的普朗克定律出发,导出了热辐射光能量与波长关系中的峰值和拐点位移公式.根据这些公式,提出了热辐射测温技术中的波长测温方法,为热辐射测温传感器的研究提供了一种全新的思路.     

固体火箭发动机管式点火器的工程设计方法

本文提出了用数值计算方法设计固体火箭发动机管式点火器的方法,计算采用四阶龙格库塔法,控制方程为一组常微分方法。应用模拟自由容积点火实验、点火器实验以及全尺寸发动机实验验证,本方法简便适用、设计可靠,有一定的工程应用和推广价值。     

复杂电磁环境下飞机火警虚警问题分析

随着航空电子技术的发展,飞机电气设备数字化程度越来越高,但它所带来的不利影响也越来越突出,即设备之间的电磁干扰(EMI)越来越强,由此造成的危害越来越多,如复杂电磁环境下出现的空中断电和火警系统的虚警问题严重影响了飞行安全.