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231.
The present paper discusses a need to develop a methodology of predicting the reliability of small thrust liquid rocket engines with a flow section made of composite materials under actual operating conditions for their successful practical use in the propulsion systems. 相似文献
232.
Grasset O. Castillo-Rogez J. Guillot T. Fletcher L. N. Tosi F. 《Space Science Reviews》2017,212(1-2):835-875
Space Science Reviews - Space exploration and ground-based observations have provided outstanding evidence of the diversity and the complexity of the outer solar system. This work presents our... 相似文献
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针对隐式极限状态方程的可靠性分析,提出了一种基于失效域样本模拟的高效线抽样法。该法采用马尔可夫链来快速得到失效域中的条件样本,利用这些失效域中的样本可以得到线抽样的重要方向,并且这些样本还可以作为线抽样的样本,来得到隐式极限状态方程失效概率的估计值。由于该法可以较准确地得到线抽样方法的重要方向,因此线抽样的效率可以得到提高,另外失效域的样本又可以作为线抽样的样本,从而进一步降低所提方法的计算工作量。算例表明所提算法的计算精度和效率均高于传统线抽样方法。 相似文献
237.
Rain.L 《中国航天(英文版)》2008,(1)
THE FOURTH BEIDOU NAVIGATION EXPERIMENTAL SATELLITE LAUNCHED The fourth Beidou experimental navigation satellite was launched into snace aton a LM-3A launch vehicle at Xichang Satellite Launch Center on February 3 at 00:28(Beijing Time).24 minutes later,the satellite separated from the launch vehicle and 相似文献
238.
Rain.L 《中国航天(英文版)》2008,(2)
FY-3A,the first satellite of China's new generation of polar-orbiting meteorological satellites,was launched into space atop a modified LM-4C launch vehicle.The satellite separated from the rocket 19 minutes after the takeoff.Flying at an altitude of 807km with an inclination of 98.8 degrees,the satellite circles in polar orbit 14 times everyday,covering the whole globe twice a day. FY-3A has a design lifetime of three years.Weighing 2295kg,the three-axis stabilized satellite is equipped with 11 remote s... 相似文献
239.
V. Truhlik D. Bilitza L. Triskova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
A database of electron temperature (Te) measurements comprising of most of the available satellite measurements in the topside ionosphere is used for studying the solar activity variations of the electron temperature Te at different latitudes, altitudes, local times and seasons. The Te data are grouped into three levels of solar activity (low, medium, high) at four altitude ranges, for day and night, and for equinox and solstices. We find that in general Te changes with solar activity are small and comparable in magnitude with seasonal changes but much smaller than the changes with altitude, latitude, and from day to night. In all cases, except at low altitude during daytime, Te increases with increasing solar activity. But this increase is not linear as assumed in most empirical Te models but requires at least a parabolic approximation. At 550 km during daytime negative as well as positive correlation is found with solar activity. Our global data base allows to quantify the latitude range and seasonal conditions for which these correlations occur. A negative correlation with solar activity is found in the invdip latitude range from 20 to 55 degrees during equinox and from 20 degrees onward during winter. In the low latitude (20 to −20 degrees invdip) F-region there is almost no change with solar activity during solstice and a positive correlation during equinox. A positive correlation is also observed during summer from 30 degrees onward. 相似文献
240.
A. Antoniou E. Danezis E. Lyratzi L.Č. Popović D. Stathopoulos M.S. Dimitrijević 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
In this paper, using the Gauss-Rotation model (GR model), we analyse the UV C IV resonance lines in the spectra of 20 Oe-stars of different spectral subtypes, in order to detect the structure of C IV region. We study the presence and behavior of absorption clouds and analyse their characteristics. From this analysis we can calculate the values of a group of physical parameters, such as the apparent rotational and radial velocities, the random velocities of the thermal motions of the ions, the Full Width at Half Maximum (FWHM), the optical depth, as well as the absorbed energy and the column density of the independent regions of matter, which produce the main and the satellite clouds of the studied spectral lines. Finally, we present the relations between these physical parameters and the spectral subtypes of the studied stars and we give our results about the structure of the C IV region in their atmosphere. 相似文献