Pg回折波的上地壳三维层析成象

提出利用人工地震Ｐｇ回折波走时重建区域上地壳三维速度分布的方法。正问题利用经典最小二乘迭代求解垂向速度梯度模型的参数值及相应走时残差。反问题采用泛函空间的最小二乘准则来实现。对速度不需要预先进行参数化处理，可以计算反演区内任意点的速度值。数值计算结果表明了该方法的可靠性。处理了滦县地震区人工地震Ｐｇ走时资料，获得了该区上地壳顶部的三维速度分布。     

A test sensitive to extreme hidden periodicities

A modified version of the widely used Kolmogorov-Smirnov (K-S) test of null hypothesis is constructed, that a given time series is Gaussian white noise, against the alternative hypothesis that the time series contains an added or multiplicative deterministic-periodic component of unspecified frequency. The usual KS test is treated as a special case. The proposed test is more powerful than the ordinary K-S test in detecting extreme (low or high) hidden periodicities. Computational procedure necessary for implementation are also given.     

Statistical regression applied to borehole strain measurements data analysis

Summary In mining and geotechnical engineering, it is usually necessary to carry out field measurements in order to obtain information. Parameters are often measured indirectly and calculated based on certain relationships to the measured quantities. More often, the number of measurements taken is greater than the minimum required, in order to increase the reliability of results. However, some data points are less reliable than others for reasons such as measurement errors; a solution which best fits the measurement data is obtained accordingly. As a result, there is a residual or a difference between the individual quantities measured and those predicted from the best-fit solution. This brings about a question of how big a residual is acceptable for a solution to be reliable. It is also important to know whether the data point with the largest residual is the most erroneous, whether those data points with large residuals should be deleted and how many of them should be deleted. Standard deviation may provide a measure of the data divergence but it is questionable if this parameter can be used as a measure of the reliability of solution. In order to solve these problems, the author has done extensive study in this area, especially as part of geotechnical data analysis. In this paper, the statistical multiple regression method is introduced to analyse the measurement data. The method is applied to the analysis ofin situ stress measurement and can be easily adopted to analyse data from other field measurements and laboratory tests. An example is included which illustrates the analysis procedure and shows the advantages of the method.     

北斗系统精密卫星钟差精度评价

针对目前北斗卫星导航系统尚未形成统一的事后轨道和钟差产品的现状,该文提出了一种较为全面的北斗卫星导航系统精密卫星钟差精度评价方法,从钟差拟合残差标准差和天跳变等方面对北斗系统事后精密卫星钟差的精度进行了评价。使用相同方法对2013年全年、2014年上半年的北斗系统精密卫星钟差产品进行了评价,以此来分析定轨策略调整对卫星钟差的影响。结果表明,武汉大学分析中心解算的北斗系统精密卫星钟差产品的精度为分米级,大部分卫星的钟差精度优于0.2m,且定轨策略调整后倾斜地球同步轨道/中地球轨道卫星钟差产品的精度有小幅度提升;定轨策略调整前卫星钟差天跳变在0.2~0.5m间,但是调整后钟差天跳变显著增大,变化范围为2~3m,建议在实际应用中对其加以慎重处理。     

Robust methods for assessing the accuracy of linear interpolated DEM

Methods for assessing the accuracy of a digital elevation model (DEM) with emphasis on robust methods have been studied in this paper. Based on the squared DEM residual population generated by the bi-linear interpolation method, three average-error statistics including (a) mean, (b) median, and (c) M-estimator are thoroughly investigated for measuring the interpolated DEM accuracy. Correspondingly, their confidence intervals are also constructed for each average error statistic to further evaluate the DEM quality. The first method mainly utilizes the student distribution while the second and third are derived from the robust theories. These innovative robust methods possess the capability of counteracting the outlier effects or even the skew distributed residuals in DEM accuracy assessment. Experimental studies using Monte Carlo simulation have commendably investigated the asymptotic convergence behavior of confidence intervals constructed by these three methods with the increase of sample size. It is demonstrated that the robust methods can produce more reliable DEM accuracy assessment results compared with those by the classical t-distribution-based method. Consequently, these proposed robust methods are strongly recommended for assessing DEM accuracy, particularly for those cases where the DEM residual population is evidently non-normal or heavily contaminated with outliers.     

多点支撑托管架支撑下的海洋管道铺设中的静力分析

本文以实际工程中点支撑托管架支撑下的海洋管道为分析对象,采用Ｂ样条函数分段拟合了从张紧器到海床间整段管道在铺设时的空间曲线,利用样条函数配点法求解管道的平衡微分方程,得到了管道在铺设过程中所必须的数据。本方法适用性好,理论简明,求解快,精度高。     

Application of teleseismic tomography to the study of shallow structure beneath Shizigou in the western Qaidam basin

Teleseismic body wave traveltime tomography is used to inverse the three-dimensional seismic velocity structure beneath Shizigou in the western Qaidam basin.The travel time are picked from the continuous observation data on a small seismic array of stations deployed during 2004-2007.The tomographic results obtained indicate that a NW-trending low velocity anomaly just beneath the target region insert northeastwards with a high dip angle.In the north, northeast and east of the low velocity anomaly, some high...     

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建立华北及西北地区垂线变化试验监测网的意义和可行性

本文介绍了天文时间和纬度观测资料的残差值在天体测量仪器周围一定范围内的地震发生前夕出现短期异常波动的现象,及不同地区天体测量仪器的观测残差与地震关系的特征,认为地方铅垂线的震前异常变化是造成天文时纬观测资料的残差值出现异常波动的主要原因.相关的研究结果曾两次获得中国科学院科技进步奖.本文还论述了该现象发展成为有效的短期地震前兆的可能性和目前该研究面临的情况,及利用天体测量仪器监测垂线变化及对其开展深入研究的意义.讨论了利用一定数量的天体测量仪器组建试验观测网对认识什么构造区带上的什么类型的地震更容易使处于何种构造区带上的时纬仪器提前出现残差异常,异常特征和时间提前量出现差别的主要原因是什么,异常与地震三要素的定量或半定量的关系,以及优化观测和提取有效信息的方法的必要性.讨论了组建观测网所需观测仪器的性能,简要介绍了中国科学院国家天文台与山东科技大学测绘学院合作试制的新仪器的特征.再次提出了在多震的华北、西北地区组建试验观测网的建议,讨论了组网的意义、可行性和有关问题.     

顾及星间单差残差的GPS斜路径水汽含量估计

基于精密单点定位(precise point positioning,PPP)技术,对海上动态GPS斜路径水汽含量(SWV)估计进行研究。在现有计算方法的基础上,提出了顾及星间单差残差的SWV提取方法。利用渤海湾船载动态GPS测量数据和同步气象观测数据,对新方法的有效性进行了验证。结果表明,相对于MM5模式积分水汽结果,采用新方法计算的SWV值的RMS为1.2mm,比传统“非差残差法”减小了1mm。