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21.
Pavel Spurný 《Earth, Moon, and Planets》1995,68(1-3):529-537
Many Perseid meteors were photographed in the Czech part of the European Fireball Network during the activity of the new strong and sharp maximum on August 12, 1993. Basic data on many of them were evaluated and radiants, atmospheric trajectories and some orbital elements are presented here and compared with atmospheric and orbital data of regular Perseids, which were photographed outside the new activity in 1993 and preceding years. No substantial difference between these two groups of Perseid meteors was found. 相似文献
22.
《中国地球化学学报》2006,25(B08):201-202
23.
针对将Kalman滤波方法应用到星载GPS定轨时,由于动态噪声和观测噪声确定不准而造成滤波的发散、污染观测值造成Kalman滤波估值的扭曲及计算舍入误差可能带来协方差阵的不正定性等缺陷,提出了一种新的综合Kalman滤波方法。该方法用拟准检定法准确地探测和修正量测方程中存在的粗差;用UD分解算法克服了数值的不稳定性,改进了计算精度;用Sage自适应滤波器克服滤波器的发散。算例结果表明,这种综合卡尔曼滤波方法具有数值稳定性好、较强的自适应性和较好地削弱粗差影响等优点。 相似文献
24.
航天INSAR复影像对的自动快速匹配 总被引:3,自引:0,他引:3
针对航天INSAR主、辅影像数据的特点,提出了加大匹配窗口、加大锚点间隔的匹配策略,以提高匹配的可靠性和速度。在匹配过程中,综合利用轨道参数和强度影像金字塔进行粗匹配,并对强度影像采用相关系数与最小二乘相结合的双向匹配方案,实现了自动、快速、高可靠性和高精度的航天INSAR复影像匹配。最后总结了航天INSAR复影像匹配的特点。 相似文献
25.
26.
岩石、土壤样品中210Po测定方法的研究 总被引:1,自引:0,他引:1
研究了以铜箔为镀片时,自沉积总α计数法定量测定岩石、土壤样品中210Po的最佳制源环境、同位素的干扰和去除、共存元素的允许量以及适宜的溶(熔)矿方法,同时研究了银、铜两种镀片的区别。试验发现,当盐酸浓度为2.0mol/L,恒温80℃,振荡频率为180次/min、振程20mm时,制源2.0h,210Po自镀回收率在99.6%~100.4%之间,210Po加入量与α净计数率线性相关系数为0.9999。放置衰变法可以消除212Bi和218Po等短半衰期核素对210Po测量产生的影响,Vc存在时其它共存元素不干扰测定。方法配合HNO3HFHClO4溶矿(对复杂试样酸溶后的不溶渣,再进行碱熔),全程回收率为99.5%~100.4%。 相似文献
27.
刘基余 《武汉大学学报(信息科学版)》2005,30(10):870-872,880
依据地月激光测距的成功实践和对卫星激光定轨的基础研究,提出了用地面对嫦娥卫星作激光测距的方法,高精度地测定嫦娥卫星绕月飞行时的实时在轨位置,论述了多站激光定轨和单站激光定轨的解算数模。 相似文献
28.
Different types of GPS clock and orbit data provided by the International GPS Service (IGS) have been used to assess the accuracy
of rapid orbit determination for satellites in low Earth orbit (LEO) using spaceborne GPS measurements. To avoid the need
for reference measurements from ground-based reference receivers, the analysis is based on an undifferenced processing of
GPS code and carrier-phase measurements. Special attention is therefore given to the quality of GPS clock data that directly
affects the resulting orbit determination accuracy. Interpolation of clock data from the available 15 min grid points is identified
as a limiting factor in the use of IGS ultra-rapid ephemerides. Despite this restriction, a 10-cm orbit determination accuracy
can be obtained with these products data as demonstrated for the GRACE-B spacecraft during selected data arcs between 2002
and 2004. This performance may be compared with a 5-cm orbit determination accuracy achievable with IGS rapid and final products
using 5 min clock samples. For improved accuracy, high-rate (30 s) clock solutions are recommended that are presently only
available from individual IGS centers. Likewise, a reduced latency and more frequent updates of IGS ultra-rapid ephemerides
are desirable to meet the requirements of upcoming satellite missions for near real-time and precise orbit determination. 相似文献
29.
We study the October 18, M
W = 7.1, 1992 Atrato earthquake, and its foreshocks and aftershocks, which occurred in the Atrato valley, northwestern Colombia. The main shock was preceded by several foreshocksof which the M
W = 6.6, October 17 earthquacke was the largest. Inparticular, we examine foreshocks and aftershocks performing joint-hypocenter relocations using high quality Pn and Sn wave readingsfrom permanent regional networks. We observed a few hours prior to the main shock a sudden increase of foreshocks. Maybe this could be used as a predictor since foreshocks have been known for other major events in the region. Our locations align for 90 km with a trend of 5° ±4° in agreement with the Harvard CMT solution showing the faultplane trending 9° to be the plane of rupture. In relation to theepicenter of the main shock, maximum intensities were located to thesouth, consistent with a rupture that traveled from north to south witha larger energy release in the south as suggested by an empirical Green'sfunction study (Li and Toksöz, 1993; Ammon et al., 1994). The boundarybetween the Panama and North Andes blocks has been placed close to thePanama-Colombia border as either a sharp boundary or a diffuse zone. TheAtrato earthquake, however, shows that the plate boundary between thePanama and North Andes microblocks is a diffuse deformation zone. Thiszone has a width of at least 2° stretching from 78°W to 76°W. Quantification of earthquake moment release (during the past30 years) in this zone shows a similar amount of moment release in thewestern and eastern parts of this zone. 相似文献
30.
大型维歇特地震仪自德国引进南京地震台已近70年。本文简要叙述了该仪器的性能;并以南京地震台的大型维歇特地震仪的记录为例,介绍了该仪器在300-2000km范围内的记录特征,回顾了该仪器在地震速报中所起的历史作用。 相似文献