SOHM型氢钟在国家授时中心的运行情况分析

上海天文台研制的型号为SOHM-3和SOHM-4的3台氢原子钟在中国科学院国家授时中心(NTSC)已经运行了一年多时间。收集了每个氢原子钟与NTSC主钟的时间比对数据。数据的分析结果给出了这几台氢钟在不同采样间隔上的频率稳定度,也显示出1台氢钟明显的相位跳变,讨论了这种相位跳变的原因。比较了这3台氢钟和从美国进口的Symmetricom公司制造的氢钟的频率稳定度的温度变化效应,指出了上海天文台研究制的氢钟存在的主要问题。     

Stability of Hamiltonian Systems with Three Degrees of Freedom and the Three Body-Problem

Results are obtained about formal stability and instability of Hamiltonian systems with three degrees of freedom, two equal frequencies and the matrix of the linear part is not diagonalizable, in terms of the coefficients of the development in Taylor series of the Hamiltonian of the system. The results are applied to the study of stability of the Lagrangian solutions of the Three Body-Problem in the case in which the center of mass is over the curve ρ_*, on the border of the region of linear stability of Routh. The curve ρ_* is divided symmetrically in three arcs in such a way that if the center of mass of the three particles lies on the central arc, the Lagrangian solution is unstable in the sense of Liapunov (in finite order), while if the center of mass determines one point that lies on one of the other two arcs of ρ_*, then the Lagrangian solution is formally stable.     

Weak stability boundary trajectories for the deployment of lunar spacecraft constellations

Suitable lunar constellation coverage can be obtained by separating the satellites in inclinations and node angles. It is shown in the paper that a relevant saving of velocity variation ΔV can be achieved using weak stability boundary trajectories. The weakly stable dynamics of such transfers allows the separation of the satellites from the nominal orbit to the required orbit planes with a small amount of ΔV. This paper also shows that only one different set of orbital parameters at Moon can be reached with the same ΔV manoeuvre starting from a nominal trajectory and ending at a fixed periselenium altitude. In fact, such a feature is proved to be common to other simpler dynamical systems, such as the two- and three-body problems.     

IAG2001年科学大会与大地测量学的最新进展

扼要报导了国际大地测量学术界的一次重要会议－IAG2001年科学大会。根据会议的学术报告，对坐标系统的统一与协调，全球重力场研究，导航卫星的应用，地壳形变与地球动力学等方面的研究进展作了详细介绍。     

中国大陆水平地壳运动的数学模型

在获得中国区域1000个实测GPS台站速度场的基础上,利用多面函数法、滑动欧拉矢量法和滑动弹塑性模型法建立了中国大陆水平地壳运动模型,统计表明3种方法外部符合精度2～4mm/a,模型互差精度约为3mm/a。     

长江三峡库区地震地形变监测研究

三峡地壳形变监测网络结合空间大地测量(GPS、InSAR)和传统大地测量的优点，在1998年以来的三峡工程建设期间和2003年水库首次蓄水中获取了大量监测成果。结果显示库区地壳运动的基本图像：垂直形变较为显著，主要来自因蓄水荷载而产生的形变，水平形变不明显．库区主要断层的活动性在蓄水期间有明显加强迹象。水准测量反映从1998年首期观测至2003年10月首次蓄水后的库区垂直位移．沉降范围较大；GPS给出了2003年蓄水前后库区的垂直位移，形变的范围主要集中在水库近岸区域。水准测量与GPS观测反应的垂直位移的量级基本一致，沉降的最大幅度在3～4cm左右。水准监测、GPS观测与重力监测结果有一定的对应性。从地壳形变监测与研究结果分析，近期负荷改变而诱发中强地震的可能性不大。     

定点潮汐形变观测与GPS大地测量

论述了我国定点潮汐形变观测与GPS在观测周期，物理量，频域，实测精度，监测优势者方面的异同，认为定点潮汐形变观测是测震学与大地测量（含GPS）的必要补充，介绍了我国定点潮汐形变观测技术的发展与台网观测技术，以及它在我国10多次中强震测报中的应用。     

The integrable cases of the planetary three-body problem at first-order resonance

This paper investigates the stability of the motion in the averaged planar general three-body problem in the case of first-order resonance. The equations of the averaged motion of bodies near the resonance surface is obtained and is analytically integrated by quadratures. The stability of the averaged motion is analytically investigated in relation to the semi-major axes, the eccentricities and the resonance phases. An autonomous second-order equation is obtained for the deviation of semiaxes from the resonance surface. This equation has an energy integral and is analytically integrated by quadratures. The quasi-periodic dependence on time with two-frequency basis of the averaged motion of bodies is found. The basic frequencies are analytically calculated. With the help of the mean functionals calculated along integral curves of the averaged problem the new analytic first integrals are constructed with coefficients periodic in time. The analytic conditions of librations of resonance phases are obtained.     

地球的弹性形变能

采用较完善的地球模型PREM，通过求解弹性体的基本运动方程，得到形变位移矢量，由此分别计算出因日月引潮力势和地球自转离心力势引起的地球的弹性形变能，它将为弹性地球运动的Hamilton表达式提供摄动项的量级估计，并将是理论上探讨地月系演化的一个重要方面。     

铁炉子断裂带侧旁地质体的构造解析及找矿方向研究

本文以构造变形为主线,将沿铁炉子断裂带侧旁的地质体划分为不同的构造均匀区段。解析了不同区段内的变形特征,总结了包括矿体就位方式和后期改造在内的综合地质事件演化序列。指出了铅锌矿的找矿方向及其它金属矿产的找矿线索。