捷联惯性导航系统重力扰动影响分析

通过EGM2008地球重力场球谐模型生成某区域重力扰动图,建立重力扰动情况下捷联惯性导航系统误差模型,仿真验证重力扰动的水平分量对捷联惯性导航误差的影响,结果表明：重力扰动的水平分量引起的捷联惯性导航系统的水平位置与速度误差以舒拉周期进行振荡,重力扰动为12.5×10 ^-5 ms ^-2时,位置误差达160 m。     

不同模型下地震位错理论的对比 及其应用进展综述

对半空间和球位错理论在理论和应用研究方面的进展进行了综合评述, 讨论了地震位错理论在海啸方面的相关研究进展和位错理论与粒子群算法结合在断层反演方面的研究进展, 对比分析了不同位错模型的优缺点, 总结了位错模型在应用中的影响因素. 本文认为不同位错理论的应用受地球分层的影响最大, 其次是重力、 曲率的影响, 而受地形、 震源深度及断层倾角等因素的影响则较小, 在实际应用中应予以综合考虑.      

融合BDS/GPS/GLONASS反演全球电离层特性研究

融合BDS/GPS/GLONASS三系统,采用载波相位平滑伪距观测值和球谐函数建立电离层延迟改正模型,并进行全球电离层反演实验。结果表明,电离层延迟格网值与IGS各分析中心最终产品对比,精度均在4 TECu以内,均值为0.675 TECu。〖JP2〗与基准站GNSS实测TEC比较,差值的均值在5 TECu以内。对计算得到的频间偏差月综合产品进行外符合精度和稳定性分析表明,GPS精度优于GLONASS,而BDS稳定性较差。     

球近似地形改正的研究分析

本文视大地水准面为球面,以计算点向径为半径,将地形分为布格球壳和球面粗糙地形,分别给出球坐标下对地面重力值的地形改正公式,并与局部地形和布格板对重力改正的计算值进行比较。结果表明,球近似粗糙地形改正与局部地形改正之间存在差异,平坦地区差异较小,在地形高超过1 000 m的山区,差异在05 mGal以上。球近似粗糙地形影响计算,易于扩展积分范围,比局部地形改正更能体现精细信息,并符合地球实际形状。布格球壳和布格板改正计算值趋势相近,幅度存在明显差异。     

Gravitational effect of distant Earth relief within the territory of former Czechoslovakia

We analyzed the gravitational effect of topography and bathymetry beyond the angular distance of approximately 1.5 degrees (referred to as the distant relief effect or DRE), and its impact on measured gravity values in the region of the former Czechoslovakia. Our work was strongly motivated by the contents of the pioneering contribution of outstanding Czech geophysicists Miloš Pick, Jan Pícha and Vincenc Vyskočil, which appeared at the turn of the 1950’s and 1960’s. Our numerical calculations were based upon the direct evaluation of the gravitational effects of compartments of a spherical layer, while the respective heights and depths were obtained from the 2 × 2 minutes digital elevation model (DEM) ETOPO2, taking into consideration also the influence of distant bathymetry. Our results are in close agreement with, but not identical to, those of the above cited authors. We also analyzed the influence of the grid cell size of the involved DEM upon the calculation results. We introduced an approximation of the analyzed effect, based on a simple linear relationship between the calculation point height, the DRE and its vertical gradient (VGDRE). Since when calculated at zero elevation the involved quantities DRE and VGDRE are smooth functions of latitude and longitude and can be easily interpolated, the approximation gives acceptable results in terms of desired accuracy of several μGal (1 μGal = 10⁻⁸ m/s²). In general, we can state that within the territories of the Czech and Slovak Republics the studied distant relief effect has negligible impact upon local gravity survey data. However, when applied to regional gravity studies, there could be a question of its possible influence in the form of a quasilinear W-E trend ranging approximately from −106.6 to −102.5 mGal within the territory of former Czechoslovakia. If we wanted to correct for this phenomenon, we should subtract this negative quantity from the standard Bouguer anomalies as they have been defined in the recent geophysical literature, thereby considerably increasing their values. But, instead of straightforward correcting the Bouguer anomalies for DRE only, we would rather recommend to wait until after the crustal and even lithospheric effects have been studied more carefully based upon the present day independent knowledge about the deep seated sources of those effects.     

2003～2008年中国东部土壤相对湿度的冠谐分析

利用2003～2008年在京津冀地区观测的146个观测站点土壤相对湿度资料,建立了年变化趋势球冠谐模型。球冠极点为东经115°,北纬38°,球冠半径为5°,球冠模型最高展开至8阶。根据模型,计算并分析了该球冠内土壤相对湿度在10cm、20cm和50cm深度年变化趋势空间分布特征。     

Study on the Dynamic Process of the Onset of South China Sea Summer Monsoon

By using the NCEP/NCAR reanalysis data from 1958 to 1997, we first looked into the atmospheric flow conditions in the one month immediately prior to the onset of the South China Sea summer monsoon （SCSSM） each year. A monthly-averaged zonal basic flow of 40-yr composite was then calculated. The stability of Rossby wave in the basic flow was studied based on the spherical barotropic vorticity equation. Furthermore, the spectral function expansion method was adopted to define and compute the evolvement of a developing wave packet. The results indicate that there exists barotropic instability of spherical Rossby wave in the climatically-averaged flow field before the SCSSM onset. The instability is triggered by the westerly jet stream in the Southern Hemisphere, and the strongest instable perturbation lies to the south of the westerly jet stream. The peak of the developing spherical Rossby wave packet propagates from mid and high latitudes to low latitudes, though not crossing the equator, spurring the cumulus convection in the tropical zones. The eruption of the cumulus convection and its spread to monsoon regions help to speed up the adjustment of the general circulation and the SCSSM onset. It is concluded that elements that contribute to the SCSSM onset are on global scale, albeit the onset itself looks like a local phenomenon.     

关于裂纹柱壳韧性断裂的研究

本文基于实验结果,利用壳单元有限元方法,对周向壁穿裂纹圆柱壳在不同初始裂纹长度条件下的弯曲韧性断裂进行了模拟,计算了裂纹尖端张开位移（ＣＴＯＤ）的裂纹起裂临界值以及裂纹连续扩展条件下裂纹尖端张开角度（ＣＴＯＡ）Ｒ曲线,考察了这些断裂参数作为材料特性的适用性。     

大气环流模式中非对流云的尺度分析

利用曾庆存的球面泛函空间方法,进行了非对流云的尺度分析,结果是:（1）对于高云,局地变化项、凝结项、平流项和垂直湍流项都是重要的;（2）对于中云除垂直平流比水平平流重要之外,其余结果与高云一样;（3）对于雨层云,凝结与局地变化是重要的;（4）对于海性层云和层积云,局地变化和垂直湍流项是重要的。以上结果对于设计大气环流模式很有参考价值。     

口径40cm天体照相仪改正镜设计

紫台口径４０ｃｍ（Ｆ／７ ．５） 双筒天体照相仪,一镜筒改用ＣＣＤ 接收器。本文设计了双分离透镜改正镜,符合ＣＣＤ 的光谱响应。试验结果表明,成象质量明显提高。