Time-domain approach to linearized rotational response of a three-dimensional viscoelastic earth model induced by glacial-isostatic adjustment: I. Inertia-tensor perturbations     

Zden&#;k Martinec  Jan Hagedoorn 《Geophysical Journal International》2005,163(2):443-462

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结合投影变换和相位相关的海冰运动监测     

胡迎迎  郎文辉  张盼  杨学志 《遥感学报》2016,20(4):579-589

为提高对渤海海冰旋转和平移运动的监测精度,提出一种基于投影变换的相位相关跟踪方法。选取连续8景静止水色成像仪(GOCI)图像序列,根据特征图像窗口的投影变换构造辅助函数,通过寻求函数最优解得到旋转角度集合,选择修正相关系数确定最佳旋转角度,同时根据相位信息实现海冰样本间亚像素级别的平移跟踪,消除传统相位相关法中因忽略图像相频特性所造成的匹配误差。实验结果表明,以手动测量的旋转角度为基准,该方法和传统相位相关法的旋转监测均方根误差的最大值/平均值分别为0.59/0.50与1.41/0.94,跟踪速度提高了50.6%;海冰平移运动的速度矢量与辽东湾的现场实测数据及历史资料记录数据基本一致。该方法对渤海海冰旋转和平移运动具有较好的跟踪效果。  相似文献   

Rotation Center and Horizontal Bearing Capacity of the Bucket Foundation in Soft Ground     

Xiaowei Tang  Xiwen Zhang  Qi Shao  Zhenqing Li 《Marine Georesources & Geotechnology》2016,34(6):594-601

In the last 20 years, the bucket foundation has been developed as a new type of offshore platform structure. Because of its short period of application to engineering practices, the theoretical decision on the rotation center and horizontal bearing capacity of the bucket foundation has yet to be agreed. A limit analysis method is used to determine the updated rotation center position and horizontal bearing capacity to evaluate the failure mechanisms of the bucket foundations. The results are compared with numerical simulation and experiments, and also with other theoretical methods. The proposed method can satisfactorily consider the engineering conditions and the result is accurate in determining the rotation center and horizontal bearing capacity.  相似文献   

用化石天长计算地球年龄的方法及意义——如何理解地球年龄          下载免费PDF全文

吴海威 《地质科学》2018,(2):774-780

天长（一天时长）是地球自转速度的直接反映。古生代-中生代化石记录的天长数据表明,古生代-中生代期间的天长随时间呈线性增加。根据角动量守恒定律,这意味着同时段地球自转速度呈线性衰减。如果把这个趋势应用于地球历史的全过程,计算结果为4.519～4.495 Ga,与目前公认的地球绝对年龄4.54 Ga一致。这意味着,从这个时间点起,地球有一种自转速度衰减的总趋势。地球自转速度衰减年龄等值于地球年龄说明：1）所测量的陨石样本生成的时间（表征地球年龄）与地球受月球吸引形成自转减速的时间几乎相同。这意味着地-月体系形成之前的地球比该陨石表征的地球年龄更为古老。2）地球、月球、自转速度衰减时长,三者的年龄呈现等值状态,因而此结果与月球起源于大碰撞的假说可以匹配。  相似文献   

Earth rotation parameter estimation by GPS observations     

YAO Yibin 《地球空间信息科学学报》2006,9(4):260-264

The methods of Earth rotation parameter （ERP） estimation based on IGS SINEX file of GPS so- lution are discussed in detail. There are two different ways to estimate ERP： one is the parameter transformation method, and the other is direct adjustment method with restrictive conditions. By comparing the estimated results with independent copyright program to IERS results, the residual systemic error can be found in estimated ERP with GPS observations.  相似文献   

内核地球自转动力学理论的研究进展(Ⅳ)——内核自转动力学方程   总被引：3，自引：3，他引：0       下载免费PDF全文

张捍卫  许厚泽  王爱生 《地球物理学进展》2006,21(4):1139-1144

本文是序列文章的第四篇,其内容包括：基于连续介质力学的基本理论,给出了固体外核（SIC）自转的动力学方程,考虑了地球的自引力、液核对内核边界的压力和二阶外部引潮力位对SIC自转的影响,并在O(mε)的量级上给出了其实用的表达式.本文的理论推导更加严密和细致,改正了文献〔1〕在推导过程中的某些错误（例如：（B39）、（B44）和（B59c）式）.本文的工作是对文献〔1〕有关理论的扩展和改进,对进一步研究内核地球自转的动力学理论是非常重要的.  相似文献   

利用奇异谱分析提高极移中长期预报精度          下载免费PDF全文

赵丹宁  雷雨  乔海花 《天文学报》2024,65(3):24

由于空间大地观测数据传输耗时及处理过程复杂, 导致极移测量值的获取存在时延, 无法满足对高精度的极移预报值有重大需求的应用领域. 针对极移复杂的时变特性, 提出一种基于奇异谱分析(singular spectrum analysis, SSA)的预报方法. 首先用SSA分离提取极移时序中的高频组分与低频组分; 其次建立最小二乘(least square, LS)外推与自回归(AutoreGressive, AR)模型对极移高频和低频组分进行组合预报. 结果表明, SSA方法能够准确地分离和提取极移低频和高频组分, 对低频和高频组分组合预报可以显著改善极移的中长期(30--365d)预报精度, 与国际地球自转和参考系服务局(International Earth Rotation and Reference Systems Service, IERS)提供的A公报中的极移预报值相比, SSA方法对极移PMX分量(本初子午线方向)和PMY分量(西90$^\circ$子午线方向)的中长期预报精度改进最高分别可达45.97%和62.44%. 研究结果验证了SSA方法对极移中长期预报改进的有效性.  相似文献   

On the “rotational angular momentum” of the oceans and the corresponding polar motion     

P. Brosche  J. Wünsch 《Astronomische Nachrichten》1994,315(2):181-188

Periodic polar motions caused by ocean tides are predicted. In the Liouville equations for rotational motion the complete excitation functions for the ocean tides have to be used. This does not depend on the fact that hydrodynamical ocean tide models do not consider the centrifugal acceleration. The observable polar motion of the Celestial Ephemeris Pole CEP (more exactly: the terrestrial location of the CEP) is tabulated for the ten ocean tides M₂, S₂, N₂, K₁, O₁, P₁, M f, M f′, M m, Ssa. Typical amplitudes for the largest ocean tides are 0.4 milliarcseconds. This is within the reach of geodetic VLBI and SLR observations.  相似文献   

The periodic variations of the core drift rate: global and zonal motions (Mitteilung des Zentralinstituts für Physik der Erde,Nr. 1746)     

H. Greiner-Mai 《Astronomische Nachrichten》1990,311(1):75-84

Toroidal zonal motions at the top of the Earth's core were computed from the observed secular variation and investigated with regard to their time dependence. Previously derived results for a pure westward drifting core could be re-examined. Additionally, the well-known 66.7 years period was found to be an oscillation of the zonal velocity field of third degree. With respect to periodic constituents, the total magnetic core-mantle coupling torque according to the zonal motions is comparable with that derived for a pure westward drifting core. Some differences in period lengthes and amplitudes do not remove previously stated differences between the spectra of the magnetic and mechanical torques on principle.  相似文献   

利用光变曲线估计猎鹰九号火箭末级的旋转状态研究     

苏向泽  汤儒峰  李荣旺  李语强 《天文研究与技术》2021,(2):203-212

光度观测是地基观测空间目标的主要手段之一,利用光度信息能够估计空间目标的相关特征信息.为了更好地了解空间目标的旋转状态,选取具有代表性的猎鹰九号火箭末级作为研究对象,由其光变信息研究旋转状态.首先利用云南天文台1.2 m光学望远镜获取猎鹰九号火箭末级的光度数据,再对目标星等进行斜距归一化,得到目标光变信息并分析目标星等...  相似文献