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181.
刘亚英 《中国空间科学技术》1997,17(4):35-40
分析研究了空间碎片数随太阳辐射流量F10.7的变化;给出预报F10.7长期变化的计算方法和预测空间碎片数的数学模型。结果显示:①强太阳活动造成空间碎片年增长率下降;②空间碎片数与太阳活动11年变化密切相关,相关数为0.9;③空间碎片增长率约为发射率的两倍;④若发射率保持不变,则到2020年,大于10cm的碎片数将达到14500;⑤若小碎片的增长为大碎片增长的两倍,则到2020年,大于1cm的碎片数可达125000。 相似文献
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183.
S.M. Park H. Kim S. Min J. Park J.H. Lee H. Kil L.J. Paxton S.-Y. Su J. Lee K.W. Min 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
We have studied the topside nighttime ionosphere of the low latitude region using data obtained from DMSP F15, ROCSAT-1, KOMPSAT-1, and GUVI on the TIMED satellite for the period of 2000–2004, during which solar activity decreased from its maximum. As these satellites operated at different altitudes, we were able to discriminate altitude dependence of several key ionospheric parameters on the level of solar activity. For example, with intensifying solar activity, electron density was seen to increase more rapidly at higher altitudes than at lower altitudes, implying that the corresponding scale height also increased. The density increased without saturation at all observed altitudes when plotted against solar EUV flux instead of F10.7. The results of the present study, as compared with those of previous studies for lower altitudes, indicate that topside vertical scale height increases with altitude and that, when solar activity increases, topside vertical scale height increases more rapidly at higher altitudes than at lower altitudes. Temperature also increased more rapidly at higher altitudes than at lower altitudes as solar activity increased. In addition, the height of the F2 peak was seen to increase with increasing solar activity, along with the oxygen ion fraction measured above the F2 peak. These results confirm that the topside ionosphere rises and expands with increasing solar activity. 相似文献
184.
美国的中性浮力模拟器及其应用 总被引:4,自引:2,他引:2
中性浮力地面模拟试验不仅可以用来训练航天员,对大型空间结构的设计及在轨组装与维修技术研究也具有重要的作用.文章对美国的三台大型中性浮力模拟器的性能、规模和配置及几次典型的大型空间结构的中性浮力模拟试验作了介绍. 相似文献
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186.
基于代价函数的组合导航系统地图匹配算法 总被引:27,自引:0,他引:27
研究了地图匹配技术在GPS(Global Positioning System)/DR(Dead Reckoning)组合导航系统中的应用,建立了GPS/DR/地图匹配组合导航系统模型,给出了一种基于代价函数和概率统计准则的地图匹配算法,通过合理地定义代价函数有效消除了存在于匹配路段挑选过程中的模糊性问题.对实际跑车数据的仿真处理结果表明,应用该算法可以为组合导航系统的定位精度带来明显的改善. 相似文献
187.
QIN Guotai QIU Shiyan HE Aiqing Zhu Yiqiang SUN Lilin LIN Xianwen LI Hong XU Xuepei 《空间科学学报》2002,22(Z1)
In this paper, thermosphere density data of "SZ-2" Atmospheric Density Detec tor From February to April 2001 are used to study the changes of the thermo sphere density in the sunshine and shaded area during solar and geomagnetic activity. The results show that in the sunshine area, the peak value of atmo spheric density changes as F10.7 varies; during geomagnetic activity, the peak value of atmospheric density in the shaded area increases as Ap increases, and start off with higher latitude, therefore move to lower latitude. 相似文献
188.
神舟4号大气成分探测的新结果 总被引:2,自引:0,他引:2
神舟4号(SZ-4)大气成分探测器搭载在SZ-4留轨舱上于2002年12月30日发射入轨,在在轨运行的前3个多月中,正值地球南半球处于夏半球季节,并发生了多次中低强度的地磁扰动事件,SZ-4大气成分探测器测得了轨道舱运行高度上(330-362km附近)大气成分的响应变化和异常现象新结果.探测数据表明,中低强度的地磁扰动事件也能引起热层大气中主要成分O和N2的数密度值增高的响应变化.同样在进入地磁扰动峰期后较高纬度处出现了N2的异常增变和O的异常降变以及大气密度异常扰动的现象,但此期间所出现异常现象的地域与SZ-3和SZ-2大气成分探测器探测结果相反,它仅位于南半球较高纬度地区. 相似文献
189.
Z.L. Du H.N. Wang H. He L.Y. Zhang R. Li Y.M. Cui 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,42(9):1457-1463
This paper is a summary of our recent researches on the applications of a weighted average method determining times of solar cycle extrema in the prediction of solar activity. Some correlation coefficients among the parameters in solar cycle according to this definition are higher than those according to the conventional definition. The descending time is found to be correlated (r = −0.77) with the ascending time 3 cycles earlier. The amplitude of solar cycle is found to be correlated (r = −0.77) with the max–max solar cycle length 2 cycles earlier. The ascending time is found to be correlated (r = −0.72) with the amplitude. A newly defined parameter called effective duration is found to be well correlated (r = 0.86) with the amplitude 5 cycles later. These correlations suggest that earlier cycles should influence later ones. The next (24th) solar cycle is estimated to start in March 2007 ± 7 months, reach its maximum in January 2011 ± 14 months, with a size of 150 ± 22, larger than those from some correlations according to the conventional definition. 相似文献
190.