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31.
跨大气层和空间区域飞行器的液体推进剂管理 总被引:1,自引:0,他引:1
根据大气层飞行环境与机动飞行特点,以及空间飞行环境与液体推进剂特点,分析了跨大气层和空间区域飞行器的保证重力场和失重状态下均无夹气液体输送、控制液体推进剂质心位移、剩余推进剂空间排放和重复使用等液体推进剂管理技术要求。阐述了相应的关键技术,如包括无夹气输送、液体质心位移控制、失重状态下的流体动力、参数确定和结构设计等管理模式确定,以及包括模型参数确定、模型、状态模拟和验证等的管理模式试验。 相似文献
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本文通过对《宇航学报》1981~1988年322篇论文中2466条参考文献的统计分析,得出以下结论,(a)宇航科学的文献情报源重在期刊类文献。(b)以《宇航学报》、《航空学报》、《AIAA,Jourual》等六种期刊类文献为重点文献。(c)中文的引文作者和论文作者相对集中。(d)期刊类文献的半衰期为8~10年。 相似文献
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INS/GPS组合导航系统的容错研究 总被引:1,自引:0,他引:1
本文研究了INS/GPS组合导航系统的容错问题,并提出了一个两级故障检测及分离方案。通过采用该方案,INS/GPS组合导航系统将具有较高的容错能力,并能为用户提供连续、精确的导航信息。 相似文献
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Nota Antonella De Marchi Guido Leitherer Claus Ragazzoni Roberto Barbieri Cesare 《Space Science Reviews》1993,66(1-4):69-73
New ultraviolet (1300 A, 3400 A),HST FOC observations have been used to derive the UV color-magnitude diagram (CMD) of R136, with the main scientific goal of studying the upper end of the stellar mass function at ultraviolet wavelengths where the color degeneracy encountered in visual CMDs is less severe. The CMD has been compared to a set of theoretical isochrones, which have been computed using the latest generation of evolutionary models and model atmospheres for early type stars. Wolf-Rayet stars are included. Comparison of theTheoretical andobserved CMD suggests that there are no stars brighter than M130–11. We use the observed main sequence turn-off and the known spectroscopic properties of the stellar population to derive constraints on the most probable age of R136. The presence of WNL stars and the lack of red supergiants suggests a most likely age of 3±1 Myr. A theoretical isochrone of 3±1 Myr is consistent with the observed stellar content of R136 if the most massive stars have initial masses around 50 M.Bases on Observations with the NASA/ESA Hubble Space Telescope, obtained at the STScI, which is operated by AURA, Inc., under NASA contract NAS5-26555.Astrophysics Division, Space Science Department, ESA 相似文献
39.
R. E. Schulte-Ladbeck G. C. Clayton C. Leitherer L. Drissen C. Robert A. Nota J. WM. Parker 《Space Science Reviews》1993,66(1-4):193-198
We are in the process of surveying the linear polarization in luminous, early-type stars. We here report on new observations of the B [e] stars S 18 and R 50, and of the Luminous Blue Variables HR Car, R 143, and HD 160529. Together with previously published data, these observations provide clear evidence for the presence of intrinsic polarization in 1 B[e] star (HD 34664) and in 5 LBVs ( Car, P Cyg, R 127, AG Car, and HR Car). The data indicate that anisotropic stellar winds are a common occurrence among massive stars in these particular evolutionary stages. For such stars, mass-loss rates estimated using the assumption of a spherical, homogeneous and stationary outflow may be in error. 相似文献
40.
Roger A. Chevalier 《Space Science Reviews》1995,74(3-4):289-298
A newly formed neutron star in a supernova finds itself in a dense environment, in which the gravitational energy of accreting matter can be lost to neutrinos. For the conditions in SN 1987A, 0.1M
may have fallen back onto the central neutron star on a timescale of hours after the explosion, after which the accretion rate is expected to drop sharply. Radiation is trapped in the flow until the mass accretion rate drops to 2×10–4
M
yr–1 at which point radiation can begin to escape from the shocked envelope at an Eddington limit luminosity. Between this neutrino limit and the Eddington limit, 3×10–8
M
yr–1, there are no steady, spherical solutions for neutron star accretion. SN 1987A should have reached the neutrino limit within a year of the explosion; the current lack of an Eddington luminosity can be attributed to black hole formation or to a clearing of the neutron star envelope. There is no evidence for newly formed neutron stars in supernovae. Radio supernovae, which were initially interpreted as pulsar activity, probably involve circumstellar interaction; SN 1993J shows especially good evidence for outer shock phenomena. 相似文献