共查询到20条相似文献,搜索用时 468 毫秒
1.
2.
天文地球动力学中的相对论效应 总被引:3,自引:0,他引:3
天文地球动力学利用空间与地面观测手段,监测和研究地球整体与各圈层的物质运动以及它们间的相互作用,这都离不开广义相对论及的时间与空间。随着空间对地观测精度的,为了充分利用高精度观测提供的信息,在天文地球动力学的研究中必须考虑相对论效应。所涉及的相对论效应包括:(1)相对论参考系的建立,(2)在恰当的参考系中对观测者和被观测对象的相对论运动方程(平动和自转)的描述,(3)观测者和被观测对象间的电磁信号传播,(4)依赖于坐标选择的结果与具有物理意义的可观测量的转换,(5)某些基本概念在定义在广义相对论框架下的重新确认。本文对天文地球动力学中的这些相对论效应作了简要的评述。 相似文献
4.
由中国天文学会天文地球动力学专业委员会、上海市天文学会和江苏省天文学会联合举办的“地球自转与地球各圈层相互关系”专题讨论会于1997年6月11日至14日在江苏省无锡市江原公寓举行.韩天艺、黄成任该讨论会的科学组织委员会主席,杨玉德、萧耐园任地方组织委员会主席.来自 相似文献
5.
中国天文学会天文地球动力学和星表与天文常数两个专业委员会于1984年12月3—8日在北京联合举办了天体测量学术年会,参加者有各天文、测地、气象、地震等19个单位的70多名代表。北京天文学会理事长冯克嘉到会讲话,祝贺年会召开。北京天文台台长王绶琯会见了与会代表,表示欢迎。 相似文献
6.
天文地球动力学利用空间与地面观测手段 ,监测和研究地球整体与各圈层的物质运动以及它们间的相互作用 ,这都离不开广义相对论涉及的时间与空间。随着空间对地观测精度的提高 ,为了充分利用高精度观测提供的信息 ,在天文地球动力学的研究中必须考虑相对论效应。所涉及的相对论效应包括 :( 1 )相对论参考系的建立 ,( 2 )在恰当的参考系中对观测者和被观测对象的相对论运动方程 (平动和自转 )的描述 ,( 3 )观测者和被观测对象间的电磁信号传播 ,( 4 )依赖于坐标选择的结果与具有物理意义的可观测量间的转换 ,( 5)某些基本概念与定义在广义相对论框架下的重新确认。本文对天文地球动力学中的这些相对论效应作了简要的评述。 相似文献
7.
8.
本文讨论了射电天文图象处理中小波分析方法的应用,同时给出了密云综合孔径射电望远镜所获得的射电图象。 相似文献
9.
中国天文学会天文地球动力学专业委员会,上海市天文学会和江苏省天文学会于1989年8月1—6日在浙江嵊泗联合举办了“天体测量,天体力学和大地测量中的相对论问题”(Relativity in Astrometry,Celestial Mechanics and Geodesy)研讨会。来自天体测量,天体力学,大地测量和天体物理领域的专家35人参加了会议。会议就相对论时空观,相对论参考系和相对论天体力学三个专题作了系统综述和讨论,并结合科研工作进展就VLBI,激光测距在测地工作中应用所需考虑的相 相似文献
10.
11.
A. R. Bestman 《Astrophysics and Space Science》1989,155(1):13-17
The transient effect on the flow of a thermally-radiating and electrically-conducting compressible gas in a rotating medium bounded by a vertical flat plate, is studied when the radiative flux satisfies the exact integral expression. The transience is provoked by a time-dependent perturbation on a constant plate temperature. The solution is constructed for the flow near and away from the plate by the Laplace transform method. The results are compared with the recent work of Bestman and Adjepong (1988). 相似文献
12.
Several techniques have been proposed for measuring speeds of meteoroids observed using radars. A recent technique involves the use of Fresnel transforms to accurately determine the speed of a meteoroid producing the trail. We follow a numerical modeling approach to analyze this technique in detail. Our studies indicate that high sensitivity to background noise levels might be a possible shortcoming of the Fresnel transform method. A matched filtering approach is presented as an alternative to alleviate this sensitivity to the noise problem. Performance of the two techniques is compared using numerical modeling and data from a 30 MHz radar. 相似文献
13.
《Chinese Astronomy and Astrophysics》2021,45(4):587-599
In radio astronomy observations, radio frequency interference (RFI) is mixed into the telescope receiving system in various forms. The existence of RFI brings misjudgment to the observation or reduces the observational signal-to-noise ratio. In recent years, the domestic and overseas radio astronomy has developed rapidly. Large-scale radio telescopes and telescope arrays at home and abroad have been constructed successively. Observation sensitivity is greatly improved, and the influence of RFI is particularly prominent. With the development of science and technology and the intensification of human activities, the RFI has become increasingly serious and irreversible. We propose to use the two-dimensional discrete wavelet transform method to analyze the data of radio astronomy observations, and to perform wavelet transform on the time-frequency sequence output by the telescope system. According to the wavelet coefficients, the every component in the original signal is separated, and the corresponding threshold value is obtained by the statistics on each component. Each component is compared with the threshold to identify the interference component, and to mark it for removal. This method is used to process the actual observation data. The results show that this method can well mark and eliminate the interference signal, and improve the observational signal-to-noise ratio. 相似文献
14.
在射电天文观测中,射频干扰(Radio Frequency Interference, RFI)会以多种形式混入望远镜接收系统,给观测带来误判或者降低观测信噪比.近年来国内国际射电天文快速发展,国内国际大型射电望远镜和阵列先后建设,观测灵敏度大为提高,射频干扰的影响尤为突出.随着科技发展和人类活动的加剧,射频干扰日益严重且不可逆转.提出利用2维离散小波变换的方法分析射电天文观测的数据,对望远镜系统输出的时间频率序列进行小波变换,根据小波系数分离出原始信号中各分量,每个分量统计得到相应的阈值,将各分量与阈值相比较识别干扰成分并标记去除.利用该方法对实际观测数据进行了处理,结果表明该方法能够很好地标记并消减干扰信号,且提高了观测的信噪比. 相似文献
15.
16.
Time transformations involving momenta in addition to the coordinates are studied from the points of view of stabilization and regularization of the equations of motion. The generalization of Sundman's transformation by using the potential function to transform the time is further generalized by using the Lagrangian function for the same purpose. The possibility of the stabilization of the equations of motion is investigated similarly to Stiefel's and Baumgarte's recent results but instead of a factorial, an additive control function is introduced in all equations of motion. The relation between the original and new independent variables is integrated by a modification of Ebert's theorem and it is shown that the new independent variable is Hamilton's principal function. Numerical examples illustrate the method and seem to indicate that the computation of close approach trajectories benefit especially by the transformations discussed. The Appendix offers an analytic treatment regarding the stabilization of the constant of energy. 相似文献
17.
本文讨论了子波变换用于信号突变检测的原理,用它分析了1700-1993年间的太阳黑子数的年均值.精确地检测到了太阳活动的突变点,用相邻两个突变点的时间长度求得了不同尺度下太阳黑子变化的周期.结果表明:利用子波变换检测太阳黑子周期与传统方法相比具有独到之处. 相似文献
18.
P. -V. Koseleff 《Celestial Mechanics and Dynamical Astronomy》1994,58(1):17-36
In this paper, the relationship between the Dragt-Finn transform and the classical Lie transform introduced by Deprit is discussed. The relative performance of the algorithms used for the computations of the transformed functions is compared, and the relation between their generators is given. These generators produce the same transform which insures the construction of the same invariants. 相似文献
19.
F. M. El-Sabaa 《Astrophysics and Space Science》1991,183(2):199-213
The Hamiltonian function of the problem of gyrostat is written in terms of Deprit's transform. The periodic solutions, using Lie's transform, are given and the condition for their stability is carried out. 相似文献
20.
总结了星族综合模型的两个要素:处于根本地位的恒星演化计算,以及把理论赫罗图转化为可观测量的光谱定标。当前恒星模型中的不确定性来自于输入的物理参数;原子数据,对流理论,辐射区的混合和和质量丢失。光谱定标不准是因为尚没有准确的温度测定,准确的分光光度测量,而且光谱库中缺少一些类型的恒星。 相似文献