先进的模块化跟踪器:一个实时的电视跟踪器

本文叙述先进的模块化跟踪器(AMT),一个可以实时跟踪诸如运载火箭、卫星等目标的电视跟踪器。AMT是美国空军菲力浦实验室为捕获、跟踪、瞄准(ATP)实验而自行开发的一个项目。它采用了DATACUBE公司并行流水式图象处理硬件和图象流软件。目前的AMT版本使用DATACUBE公司的 MAXVIDEO一20、MAXSCAN和MAX860板。AMT可同时对二个不同的视频输入进行行星、边缘和相关跟踪,并可实时进行输入图象的视频转换、实时直方图计算及图象的处理。AMT具有自动捕获跟踪目标,自动调节阈值和波门大小的能力,它可用于任何地基、空基和天基等需要自动跟踪的应用场合。     

任务操作中心——航天器地面数据系统关键部件的一体化

在以减少预算、限定系统开发时间和用户要求增加能力为特征的环境中,国家航空航天局开达德航天中心的任务操作处(MOD)在开发其航天地面数据系统方面提出了一个新的、高经济效益的新概念:任务操作中心(MOC)。按这种称为的方法,使用一种现代化的图形用户接口把关键部件集成为一个集航天器规划、监视、遥制为一体的综合系统。MOD目前正在构造多个MOC,其特点是采用通用的、可重复使用的和可扩展的系统结构,可支持X射线定时探测卫星(XTE)、热带降雨测量卫星(TRMM)和先进合成探测(ACE)卫星。 由于有了MOC方法,各种任务操作集合成整体,用户用一个系统即可完成实时健康和安全监视、实时遥控、实时姿态处理、航天器实时和预测性图形式监视、趋势分析、任务规划和调度、指令生成和管理、测控网调度、引导星选择;用专家系统进行航天器监视以及故障排除。MOD还准备按新的MOC管理机构构造测试和训练模拟器。 本文描述了MOC的概念,开发MOC系统中所使用的管理办法,使用的技术和构造MOC系统中对开发过程进行的改进,以及采用MOC法对用户和卫星工程带来的预期益处。     

煤油在超声速气流中非定常横向喷射的实验观察

本文目的是研究煤油在超声速气流中非定常横向喷射问题,并与静止和亚声速气流中的结果进行对比。改造普通油嘴并采用单次高压燃油喷射系统,得到不同延时的流场阴影照片。结果表明：在超声速气流中,射流柱破碎是由迎风面的表面波引起的,破碎点位于表面波的波谷。雾化过程过分四个区域。射流激波由近射流柱的迎风面,并在人壁反射,非定常喷射的波系演化复杂。煤油在亚声速气流中喷射,不存在射流激波,破碎点沿射流柱上移,穿透深     

航空发动机2 级风扇的数值研究

运用ANSYS CFX 11.0和home-code程序对AI222发动机风扇流路气动参数进行了3维CFD(Computational Fluid Dynamics)计算;通过3维建模,实现了风扇主要积分特性和局部参数计算。通过与风扇进行大量试验结果的对比,验证了计算结果,并找出了产生差别的原因,得到了风扇总特性以及气流径向参数的计算值与试验值的吻合度。结果表明:通过运用3维建模计算方法简化了风扇设计过程,缩短了风扇从设计到试验的时间,降低了航空发动机部件的设计成本。     

一种具有数字信号处理功能的铯频标方波调频伺服系统

本文介绍一种具有数字信号处理功能的伺服系统,该系统近来已经应用于铯频率标准之中。与以前的伺服系统相比,它采用了一个具有2赫频率调制的模拟锁定系统。新的系统具有多种优点,例如:调制和解调的线性好,信号处理的直流失调小并容易补偿到最佳控制。其他实验室所做的实验表明:输出信号的线性直流漂移可用二阶差分的信号处理方法消除。本文中介绍了采用高阶差分计算处理的伺服系统的实验结果及理论分析。结果表明,它对于改进频率稳定度看来是十分有效的。     

Classification of modern and old Río Tinto sedimentary deposits through the biomolecular record using a life marker biochip: implications for detecting life on Mars

The particular mineralogy formed in the acidic conditions of the Río Tinto has proven to be a first-order analogue for the acid-sulfate aqueous environments of Mars. Therefore, studies about the formation and preservation of biosignatures in the Río Tinto will provide insights into equivalent processes on Mars. We characterized the biomolecular patterns recorded in samples of modern and old fluvial sediments along a segment of the river by means of an antibody microarray containing more than 200 antibodies (LDCHIP200, for Life Detector Chip) against whole microorganisms, universal biomolecules, or environmental extracts. Samples containing 0.3-0.5?g of solid material were automatically analyzed in situ by the Signs Of LIfe Detector instrument (SOLID2), and the results were corroborated by extensive analysis in the laboratory. Positive antigen-antibody reactions indicated the presence of microbial strains or high-molecular-weight biopolymers that originated from them. The LDCHIP200 results were quantified and subjected to a multivariate analysis for immunoprofiling. We associated similar immunopatterns, and biomolecular markers, to samples with similar sedimentary age. Phyllosilicate-rich samples from modern fluvial sediments gave strong positive reactions with antibodies against bacteria of the genus Acidithiobacillus and against biochemical extracts from Río Tinto sediments and biofilms. These samples contained high amounts of sugars (mostly polysaccharides) with monosaccharides like glucose, rhamnose, fucose, and so on. By contrast, the older deposits, which are a mix of clastic sands and evaporites, showed only a few positives with LDCHIP200, consistent with lower protein and sugar content. We conclude that LDCHIP200 results can establish a correlation between microenvironments, diagenetic stages, and age with the biomarker profile associated with a sample. Our results would help in the search for putative martian biomarkers in acidic deposits with similar diagenetic maturity. Our LDCHIP200 and SOLID-like instruments may be excellent tools for the search for molecular biomarkers on Mars or other planets.     

Pumice as a remarkable substrate for the origin of life

The context for the emergence of life on Earth sometime prior to 3.5 billion years ago is almost as big a puzzle as the definition of life itself. Hitherto, the problem has largely been addressed in terms of theoretical and experimental chemistry plus evidence from extremophile habitats like modern hydrothermal vents and meteorite impact structures. Here, we argue that extensive rafts of glassy, porous, and gas-rich pumice could have had a significant role in the origin of life and provided an important habitat for the earliest communities of microorganisms. This is because pumice has four remarkable properties. First, during eruption it develops the highest surface-area-to-volume ratio known for any rock type. Second, it is the only known rock type that floats as rafts at the air-water interface and then becomes beached in the tidal zone for long periods of time. Third, it is exposed to an unusually wide variety of conditions, including dehydration. Finally, from rafting to burial, it has a remarkable ability to adsorb metals, organics, and phosphates as well as to host organic catalysts such as zeolites and titanium oxides. These remarkable properties now deserve to be rigorously explored in the laboratory and the early rock record.     

X波段机载雷达的收发模块

增强雷达性能的要求和对付越来越复杂威胁环境的需要促使了地面雷达、船载雷达和机载雷达系统的有源相控阵的研制。对于机载系统，电子扫描波束指向能力所带来的益处是灵活、高效的扫描范围覆盖、工作模式的交替进行（例如同时进行搜索、多目标跟踪和地形回避等）以及在每个工作模式中的动态波束方向图形状优化等。像可靠性增强和雷达横截面降低等其他系统益处也能在此种天线中加以证明。