Design of ASTROD-GW Orbit

The ASTROD-GW (ASTROD [Astrodynamical Space Test of Relativity Using Optical Devices] Optimized for Gravitation Wave Detection), the mission of the laser astrodynamical gravitational wave detection, is the scheme of optimality of the gravitational wave detection on which the ASTROD is concentrated. Its spacecraft orbits form a triangular array close to an equilateral triangle in the vicinity of the solar-terrestrial Lagrangian points L₃, L₄ and L₅. The length of the interference arm is about 2.6 × 10⁸ km and the detectable wavelength of the gravitational wave is 52 times larger than that detected by the LISA (Laser Interferometer Space Antenna). In this article, the design and optimization method of the ASTROD-GW orbit are summarized. After the orbit is optimized, the variation in the arm length difference (which can be called the interference difference in laser interferometry) within 10 years is in the order of magnitude of 10⁻⁴ AU. The Doppler velocities in the three arm length directions are smaller than 4 m/s, and all of them are less than that required by the LISA. Therefore the laser ranging techniques developed by the LISA can be applied to the ASTROD-GW.     

基于CHAMP卫星星历反演地球重力场的两种方法

根据模拟的CHAMP卫星星历,分别采用基于牛顿运动定律的数值微分法和基于能量守恒定律的能量守恒法建立观测方程,恢复出50阶次的重力位系数。同时,考虑到CHAMP卫星位置、速度和加速度存在的误差,分析了这两种方法对各项精度指标的敏感程度,并比较了这两种方法的优缺点。     

Tectonic vs. gravitational morphostructures in the central Eastern Alps (Italy): Constraints on the recent evolution of the mountain range

Deep-seated gravitational slope deformations (DSGSDs) influence landscape development in tectonically active mountain ranges. Nevertheless, the relationships among tectonics, DSGSDs, and topography are poorly known. In this paper, the distribution of DSGSDs and their relationships with tectonic structures and active processes, surface processes, and topography were investigated at different scales. Over 100 DSGSDs were mapped in a 5000 km² sector of the central Eastern Alps between the Valtellina, Engadine and Venosta valleys. Detailed lineament mapping was carried out by photo-interpretation in a smaller area (about 750 km²) including the upper Valtellina and Val Venosta. Fault populations were also analysed in the field and their mechanisms unravelled, allowing to identify different structural stages, the youngest being consistent with the regional pattern of the ongoing crustal deformation. Finally, four DSGSD examples have been investigated in detail by geological and 2D geomechanical modelling.DSGSDs affect more than 10% of the study area, and mainly cluster in areas where anisotropic fractured rock mass and high local relief occur. Their onset and development is subjected to a strong passive control by mesoscopic and major tectonic features, including regional nappe boundaries as well as NW–SE, N–S and NE–SW trending recent brittle structures. The kinematic consistency between these structures and the pattern of seismicity suggests that active tectonics may force DSGSDs, although field evidence and numerical models indicate slope debuttressing related to deglaciation as a primary triggering mechanism.     

琼东南盆地北礁凹陷多边形断层发育特征及成因

基于高精度三维地震解释和相干属性分析,发现琼东南盆地北礁凹陷三维区中新统三亚组、梅山组、黄流组发育大量多边形断层。梅山组顶面发育呈近EW向展布的长条形丘和丘间底流水道,其上方分别发育近EW向(多边形)断层密集带和近SN向横截水道(多边形)断层。北部泥岩区,丘规模越大,断层密集带越宽,断层密集带主要分布在黄流组下部和梅山组上段地层中,横截底流水道断层向上延伸较短,向下延伸至梅山组或三亚组,而梅山组至三亚组多边形断层逐渐呈现多边形形态。西南部砂岩区,黄流组底部断层密集带和横截水道断层比北部规模小,延伸短,梅山组下段发育近NE向横截浊积水道砂岩断层和近NW向平行浊积水道边界断层,其规模更小。重力扩展可以很好地解释黄流组断层密集带和横截底流水道断层的形成,梅山组和三亚组的多边形断层是超压水力破裂的结果,同时大颗粒砂岩抑制多边形断层的形成。在我国首次发现断层密集带和横截水道断层,该类断层对油气运移、识别强振幅地质体和丘形反射成因具有重要的意义。     

Gravitational potential energy of the Sun

Summary The gravitational potential energy of the Sun and its corresponding internal energy have been estimated on the basis of the standard model of the Sun's internal structure. It is demonstrated that the principal moment of inertia of the Sun, computed from the model, does not fit the hydrostatic equilibrium limit.     

利用CHAMP卫星星历恢复引力位模型的模拟研究

对CHAMP卫星星历恢复引力位模型的精度，使用3种方法和不同积分弧长作了模拟计算，结果表明，采用正则化方法并扩展积分弧长将有助于提高解算法系数的精度，预期CHAMP卫星观测将使现有引力位模型低阶位系数的精度提高1－2个数量级。     

海洋非潮汐变化对时变重力场的影响

基于全球海洋数值模式，估计了海水质量非潮汐变化对低阶地球引力场季节性变化的贡献。激发模型预测的大气、地表水、海洋潮汐和非潮汐变化对引力场的组合影响被用来与卫星激光测距(SLR)的观测值进行比较。结果表明，在季节性变化时问尺度上，为克服海洋数值模式的体积守恒近似而采用的质量守恒改正对△J2具有较明显的影响，对△J3的影响可以忽略，SLR观测的△J2周年和半年振幅介于海洋、地表水、大气(IB)和(NIB)的组合结果之间。     

高低跟踪方式卫星重力观测的状态空间描述

当前的重力卫星任务除了本身特有的观测方式外，都采用了高低卫卫跟踪的观测方式。为研究高低卫卫跟踪观测系统的时变行为和获取重力场信息的能力，文中运用描述时变系统的状态空间模型方法，根据附加参数的类型，建立了3种状态空间模型，并对系统的可观测性从解析法的角度进行了分析。结果表明，对于单一的高低卫卫跟踪观测系统，引力系数的可观测性实际上是不成立的，根据一次任务只能建立引力系数的一组约束条件。