航空发动机燃烧室出口温度场双向测量方法

介绍了1种航空燃烧室出口温度场正、反向测量的新方法。使用1个角度传感器(编码器)记录摆动装置的双向转动角度,达到了双向采集和测量温度场数据的目的;在程序中设定正、反向切换时的空程,在测量中予以消除,解决了齿轮传动中存在的空程角度难题,使得正、反向旋转测量的实际位置一致,保证了温度场试验数据的重复性。试验证明温度场数据较好地满足了重复性的要求。     

Microwave Brightness Temperature and Lunar Soil Dielectric Property Retrieve

Among many scientific objectives of lunar exploration, investigations on lunar soil become more and more attractive to the scientists duo to the existence of abundant 3He and ilmenite in the lunar soil and their possible utilization. Although the soil composition determination on the lunar surface is available by visible light spectrometer,γ/X-ray spectrometer etc, the evaluations on the total reserves of 3He and ilmenite in the lunar deep and on the thickness of the lunar soil are still impossible so far. In this paper, the authors first give a rough analysis of the microwave brightness temperature images of the lunar disc observed using the NRAO 12 Meter Telescope and Siberian Solar Radio Telescope; then introduce our researches on the microwave dielectric properties of lunar soil simulators; finally, discuss some basic relations between the microwave brightness temperature and lunar soil properties.     

矩形波导H—E面均匀弯头的多模等效网络表示法

矩形波导的均匀弯头是许多地面及空间微波子系统经常使用的器件。因此，需要利用它们精确，有产儿的全波特性来开发用以分析和设计复杂波导结构的现代ＣＡＤ工具。     

B-2今年将进入初步作战状态

美军方和国会在对是否增加B-2轰炸机采购量的问题进行了几番激烈的争论之后,最后终于作出了不再增加采购量的决定。即在1997财年无需为采购附加的B-2轰炸机投资。空军关于B-2轰炸机的采购工作将在第20架时结束。至此,美国为该机的发展和研究以及采购的总投资额将保持在444亿美元。     

Discrimination of aqueous and aeolian paleoenvironments by atomic force microscopy-- a database for the characterization of martian sediments

In the search for aqueous habitats on Mars direct proof of (ancient) flowing water is still lacking, although remote sensing has provided indications of young fluvial systems. To demonstrate that such proof can be given, we examined surface marks on recent terrestrial sand grains by atomic force microscopy (AFM) and applied a quantitative three-dimensional analysis that can numerically distinguish between aeolian and aquatic transport mechanisms in sedimentary deposits on Earth. The surfaces of natural quartz grains as well as olivine, feldspar pyroxene, and monazite sands of known origin were imaged, each image yielding a three-dimensional map of the mineral surface. A fully automated analysis of distribution patterns of the structural elements that constitute the grain surfaces shows that wind-transported quartz grains have short linear elements irregularly distributed on the surface. Linear elements on water-transported grains, however, are longer with orientations that reflect the mineral symmetry. Because the surface patterns found on aqueous grains are due to preferential etching, they can be used as diagnostic fingerprints for the existence of past or present aqueous transport systems. We used a cluster analysis of the cross-correlation distance of distribution patterns in the structures of aeolian and aquatic sand grains to build a phenogram that provides a map for the relationship of the various sediments found on earth. The analysis shows that the method is highly significant and that water and wind transport can clearly be differentiated. In particular, feldspar and olivine sands contributed even more to the discrimination than quartz grains, which indicated that the method is promising for its application on future missions to Mars. Assuming that martian aqueous sand grains exhibit similar erosional patterns to mineral grains on Earth, simple AFM experiments on a Mars lander would be capable of proving the activity of flowing water in modern runoff systems and of analyzing the paleoenvironments of Mars.     

航天飞机指控中心Unix工作站中专家系统的实时数据获取

最具代表性的美国技术杰作之一可能是位于德克萨斯州休斯顿的约翰逊航天中心的航天指挥控制中心(MCC)。该中心各指挥室经历了美国技术史上许多重大事件,如首次登月、营救天空实验室以及首次发射航天飞机。60年代初MCC首次启用时,的确是技术杰作。然而该设施自阿波罗任务后只进行过不大的改进。直到最近,它仍然维持着以单主机的结构,     

OPTIMAL CONTROL OF REDUNDANT ROBOTS WITH LOCAL DEGREES OF FREEDOM

SupportedbytheNationalNaturalScienceFoundationofChinaRedundantrobotsprovideflexibilityinavarietyoftasks.Methedsusedtodevelopthere-dundancycontrolarewellknown[1~4J-Inthesemethods,kinematicflexibilityisensuredwhiledynamicperformanceisbeingimproved.Itisverydifficult,however,toimplementoptimalredundancycontrolthatsimultaneouslyincludesbothkinematicsanddynamics(dual-optimiza-tion)forrobotmechanismsthathavebeenpreviouslydeveloped.Inthefollowingsections,aredundantrobotmechanismhavinglocaldegreesof…