Dynamical History of the Earth–Moon System     

G. A. Krasinsky 《Celestial Mechanics and Dynamical Astronomy》2002,84(1):27-55

Differential equations describing the tidal evolution of the earth's rotation and of the lunar orbital motion are presented in a simple close form. The equations differ in form for orbits fixed to the terrestrial equator and for orbits with the nodes precessing along the ecliptic due to solar perturbations. Analytical considerations show that if the contemporary lunar orbit were equatorial the evolution would develop from an unstable geosynchronous orbit of the period about 4.42 h (in the past) to a stable geosynchronous orbit of the period about 44.8 days (in the future). It is also demonstrated that at the contemporary epoch the orbital plane of the fictitious equatorial moon would be unstable in the Liapunov's sense, being asymptotically stable at early stages of the evolution. Evolution of the currently near-ecliptical lunar orbit and of the terrestrial rotation is traced backward in time by numerical integration of the evolutional equations. It is confirmed that about 1.8 billion years ago a critical phase of the evolution took place when the equatorial inclination of the moon reached small values and the moon was in a near vicinity of the earth. Before the critical epoch t _cr two types of the evolution are possible, which at present cannot be unambiguously distinguished with the help of the purely dynamical considerations. In the scenario that seems to be the most realistic from the physical point of view, the evolution also has started from a geosynchronous equatorial lunar orbit of the period 4.19 h. At t < t _cr the lunar orbit has been fixed to the precessing terrestrial equator by strong perturbations from the earth's flattening and by tidal effects; at the critical epoch the solar perturbations begin to dominate and transfer the moon to its contemporary near-ecliptical orbit which evolves now to the stable geosynchronous state. Probably this scenario is in favour of the Darwin's hypothesis about originating the moon by its separation from the earth. Too much short time scale of the evolution in this model might be enlarged if the dissipative Q factor had somewhat larger values in the past than in the present epoch. Values of the length of day and the length of month, estimated from paleontological data, are confronted with the results of the developed model.  相似文献   

A permanent seismic station beneath the Ocean Bottom     

David Harris  Robert K. Cessaro  Fred K. Duennebier  David A. Byrne 《Marine Geophysical Researches》1987,9(1):67-94

The Hawaii Institute of Geophysics began development of the Ocean Subbottom Seisometer (OSS) system in 1978, and OSS systems were installed in four locations between 1979 and 1982. The OSS system is a permanent, deep ocean borehole seismic recording system composed of a borehole sensor package (tool), an electromechanical cable, recorder package, and recovery system. Installed near the bottom of a borehole (drilled by the D/V Glomar Challenger), the tool contains three orthogonal, 4.5-Hz geophones, two orthogonal tilt meters; and a temperature sensor. Signals from these sensors are multiplexed, digitized (with a floating point technique), and telemetered through approximately 10 km of electromechanical cable to a recorder package located near the ocean bottom. Electrical power for the tool is supplied from the recorder package. The digital seismic signals are demultiplexed, converted back to analog form, processed through an automatic gain control (AGC) circuit, and recorded along with a time code on magnetic tape cassettes in the recorder package. Data may be recorded continuously for up to two months in the self-contained recorder package. Data may also be recorded in real time (digital formal) during the installation and subsequent recorder package servicing. The recorder package is connected to a submerged recovery buoy by a length of bouyant polypropylene rope. The anchor on the recovery buoy is released by activating either of the acoustical command releases. The polypropylene rope may also be seized with a grappling hook to effect recovery. The recorder package may be repeatedly serviced as long as the tool remains functionalA wide range of data has been recovered from the OSS system. Recovered analog records include signals from natural seismic sources such as earthquakes (teleseismic and local), man-made seismic sources such as refraction seismic shooting (explosives and air cannons), and nuclear tests. Lengthy continuous recording has permitted analysis of wideband noise levels, and the slowly varying parameters, temperature and tilt.Hawaii Institute of Geophysics Contribution 1909.  相似文献   

风暴潮灾与月相     

郭洪寿  陈祥福 《海洋预报》1992,9(2):39-45

本文以实测资料为依据,统计分析了风暴潮灾、风暴潮、登陆台风、天文高潮等与月相的关系。统计资料表明,登陆台风和台风风暴潮发生在大(小)潮期的次数相对较多,略大于平均数,但它们与月相没有明显的因果关系,它们相对于月相的分布大致上是随机的,如果台风在天文大潮期间登陆,台风引起的暴潮与天文潮叠加后成灾的概率明显增大,但也不一定成灾;成了灾的,往往是风暴潮峰值适逢当日的天文高潮所致。  相似文献   

"嫦娥"卫星绕月飞行轨道的激光测定法     

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   

涡流地震检波器的理论研究     

王宝昌  董连芝  董世学 《吉林大学学报(地球科学版)》1995,(4)

根据严格的数学推演给出涡流地震检波器电压的频率响应特性、阻尼因数、位相等的正确公式；定义表征其某些基本特征的物理量；讨论了文献［１］中某些严重错误，简介了我们研制的新型涡流地震检波器的某些性能。  相似文献   

Low Energy Transfer to the Moon   总被引：15，自引：0，他引：15  

W. S. Koon  M. W. Lo  J. E. Marsden  S. D. Ross 《Celestial Mechanics and Dynamical Astronomy》2001,81(1-2):63-73

In 1991, the Japanese Hiten mission used a low energy transfer with a ballistic capture at the Moon which required less Vthan a standard Hohmann transfer. In this paper, we apply the dynamical systems techniques developed in our earlier work to reproduce systematically a Hiten-like mission. We approximate the Sun–Earth–Moon-spacecraft 4-body system as two 3-body systems. Using the invariant manifold structures of the Lagrange points of the 3-body systems, we are able to construct low energy transfer trajectories from the Earth which execute ballistic capture at the Moon. The techniques used in the design and construction of this trajectory may be applied in many situations.  相似文献   

FBS-3A型反馈式宽频带地震计电流标定方法研究   总被引：1，自引：0，他引：1       下载免费PDF全文

刘庆伟  庄灿涛 《地震学报》2001,23(2):192-203

随着时间的推移和环境条件的缓慢变化，地震计各部件的性能参数会有所改变，及时了解这种变化并加以控制和调整，有助于提高地震计输出结果的可信度．所以，一台地震计无论在交付使用前，还是在使用过程中，都需要进行标定．目前，比较常用的标定方法有方波电流标定和正弦电流标定．本文从系统分析的角度出发，在分析得到地震计传递函数的基础上，将方波电流标定和正弦电流标定过程进行理论抽象，进而在复频域对两种电流标定过程进行仿真推导；并在此基础上，讨论了方波电流标定输出曲线与地震计固有参数之间以及正弦电流标定的稳态输出与标定电流之间的关系，并且论述了两组特定频率正弦电流的标定输出之间的关系．最后，作为理论分析在实践中的具体应用，给出了两种电流标定过程在实际工作中的应用方法．本文旨在阐明两种常用的电流标定方法的物理意义，对地震计的调试及应用有积极的参考作用．   相似文献   

利用深井地震速度记录确定震级的初步研究     

李慧民  朱元清  章纯 《地震地磁观测与研究》1992,(5)

利用上海遥测地震台网虹桥、南汇台深井地震速度记录资料讨论地震尾波衰减与震级关系.采用统计方法求得了用垂直向地震波持续时间 L 测定震级M_v 的公式M_v 虹桥=-0.981+1.677×log(L)+0.600×log(△)±0.22M_v 南汇=-1.461+1.979×log(L)+0.506×log(△)±0.22结果表明,地震速度记录的持续时间 L 的对数加上震中距(△,单位:km)的对数与震级在近震范围内(△<5°)呈线性关系,说明用地震速度记录同样可以测定地震震级,这有助于提高深井速度记录资料的推广和应用。  相似文献   

CT-1地震计传递函数测试仪的设计   总被引：6，自引：4，他引：2  

周云耀  蔡亚先  吕永清  程骏玲 《大地测量与地球动力学》2002,22(3):117-121

将计算机控制技术应用到甚宽频带地震计的传递函数测试中。讨论了基本的测试方法和原理，阐述了传递函数测试系统的软、硬件设计，给出了测试系统的应用实例。该测试系统具有正弦波自动扫频、阶跃信号法和脉冲信号法等标定方法，满足了甚宽频带地震计的传递函数测试在观测频带、动态范围和测试精度等方面的要求。  相似文献   

��������ұ궨�Զ�����ϵͳ   总被引：1，自引：0，他引：1  

吕永清  蔡亚先 《大地测量与地球动力学》2007,27(5):119-122

?????Я????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????  相似文献