基于移动曲面模型的GPS高程拟合

移动曲面模型具有连续性函数模型和离散性函数模型的双重特征,是GPS高程拟合模型中一个比较有应用优势的模型。推导出了该模型的一般形式,并用该模型进行了一个实例计算,效果良好。     

半参数平差模型参数的两步估计

考虑半参数平差模型L=Bx+S+Δ,xεRd,S为未知回归参数,为未知Borel函数。本文首先利用自然样条函数法,找到符合条件的非参数自然样条插值函数。其次利用偏残差法并综合最小二乘法,导出了参数和非参数的解算公式,讨论了窗宽参数的选取方法。在本文的最后,将这种估计方法应用到重力场的计算中,说明了利用半参数平差模型估计参数的有效性。     

南北地震带现今应变特征及地震危险性分析

基于1999～2007期、2009～2013期及2013～2016期GPS速度场数据,利用最小二乘配置方法解算南北地震带附近区域应变率参数,对比应变率变化并分析变化原因。结合研究时段内M_W6.0以上地震的震中分布,分析应变率参数与地震分布的相关关系;再结合地震地质,分析研究区内主要断层的地震危险性。结果显示,青藏高原近期存在加速扩展特征,其东北缘存在明显的介质性质横向不均匀特征,M_W6.0以上地震与应变率的大小存在相关关系;研究区内的地震危险区分别为祁连山中段危险区、玛沁-玛曲危险区、安宁河-小江断裂系危险区及红河断裂带中南段危险区。     

基于Cook距离的协方差函数拟合点优选

进行最小二乘配置中的协方差函数拟合时,选取的拟合点应尽可能反映该区域的异常位的实际情况。提出基于Cook距离的协方差函数拟合点优选,计算所有拟合点的Cook距离,剔除拟合模型中的强扰动点,再进行协方差函数拟合。结合GPS高程拟合实例分析,文中方法可以有效提高高程拟合精度,并且通过Cook距离可以对拟合点进行精简和检出拟合点中误差较大点或粗差点。     

An improved geopositioning model of QuickBird high resolution satellite imagery by compensating spatial correlated errors

A lot of studies have been done for correcting the systematic biases of high resolution satellite images (HRSI), which is a fundamental work in the geometric orientation and the geopositioning of HRSI. All the existing bias-corrected models eliminate the biases in the images by expressing the biases as a function of some deterministic parameters (i.e. shift, drift, or affine transformation models), which is indeed effective for most of the commercial high resolution satellite imagery (i.e. IKONOS, GeoEye-1, WorldView-1/2) except for QuickBird. Studies found that QuickBird is the only one that needs more than a simple shift model to absorb the strong residual systematic errors. To further improve the image geopositioning of QuickBird image, in this paper, we introduce space correlated errors (SCEs) and model them as signals in the bias-corrected rational function model (RFM) and estimate the SCEs at the ground control points (GCPs) together with the bias-corrected parameters using least squares collocation. With these estimated SCEs at GCPs, we then predict the SCEs at the unknown points according to their stochastic correlation with SCEs at the GCPs. Finally, we carry out geopositioning for these unknown points after compensating both the biases and the SCEs. The performance of our improved geopositioning model is demonstrated with a stereo pair of QuickBird cross-track images in the Shanghai urban area. The results show that the SCEs exist in HRSI and the presented geopositioning model exhibits a significant improvement, larger than 20% in both latitude and height directions and about 2.8% in longitude direction, in geopositioning accuracy compared to the common used affine transformation model (ATM), which is not taking SCEs into account. The statistical results also show that our improved geopositioning model is superior to the ATM and the second polynomial model (SPM) in both accuracy and reliability for the geopositioning of HRSI.     

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A multi-subwaveform parametric retracker of the radar satellite altimetric waveform and recovery of gravity anomalies over coastal oceans

The quality of satellite radar altimetric data is very important in studies of geodesy,geophysics,and oceanography.Over coastal oceans,altimeter waveforms are contaminated by the terrain and physical environments so that the accuracy of altimeter data is lower than that over open oceans.Here we develop a new multi-subwaveform parametric retracker(MSPR) to improve the quality of altimeter data for the recovery of gravity anomaly in coastal oceans.The least squares collocation method is used to recover the residual gravity anomaly over the coastal water from altimetric data.The waveform data records from Geosat/GM around Taiwan Island are practically retracked with MSPR.When compared with the Taiwan geoid height,the results retracked by MSPR are more accurate than those retracked by the well-known β-5-parmeter method and from the geophysical data records(GDRs).The gravity anomalies over Taiwan coastal waters are calculated from the retracked altimeter data with the least squares collocation.When we compared gravity anomalies computed using altimeter GDRs with the ship-borne gravity data over Taiwan coastal ocean,we found that the results from retracked data are more accurate than those from GDRs.     

节理岩体力学性能不确定性分析方法研究

基于连续介质损伤力学框架,通过损伤张量和有效应力来描述节理岩体的力学性能,自主研发了基于损伤力学模型的有限元程序（CD-FEM）,用于节理岩体等效力学性能研究。同时,采用Karhunen-Loeve（K-L）展开来分解随机输入场,用混沌多项式来表示随机输出场,采用概率配点法生成配点,再由连续损伤有限元分析系统CD-FEM求解确定性方程组,最终得到输出域的统计数据,从而提出了一种将随机分析与基于连续损伤力学模型的数值分析方法解耦进行节理岩体不确定性力学行为分析的方法。利用该方法,对一典型节理岩体在加载条件下的力学行为进行不确定性分析,并与蒙特卡罗方法进行对比,结果表明,所提方法的计算量大大减少,极大地提高了节理岩体力学性能不确定性分析的效率,可应用于对节理岩体在不同载荷条件下的不确定性进行分析。     

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汶川地震前龙门山断裂带闭锁程度和滑动亏损分布研究

利用1999—2007期GPS水平速度场数据,采用Defnode负位错反演程序估算了龙门山断裂在汶川地震前的闭锁程度和滑动亏损分布,结合龙门山断裂带附近地表水平应变率场结果,综合分析了震前地壳变形特征.反演结果表明,震前龙门山断裂中北段处于完全闭锁状态,闭锁深度达到21 km(闭锁比例0.99)左右,垂直断层方向的挤压滑动亏损速率约为2.2 mm/a,平行断层方向的右旋滑动亏损速率约为4.6 mm/a.龙门山断裂南段只有地表以下12 km闭锁程度较高(闭锁比例0.99),垂直断层方向滑动亏损速率约为1.4 mm/a,平行断层方向滑动亏损速率约为4.6 mm/a;在12~16 km处闭锁比例约为0.83,垂直断层方向滑动亏损速率约为1.2 mm/a,平行断层方向滑动亏损速率约为3.8 mm/a;在16~21 km处闭锁比例约为0.75,垂直断层方向滑动亏损速率约为1.1 mm/a,平行断层方向滑动亏损速率约为3.5 mm/a.在21~24 km处整条断裂均逐步转变为蠕滑.上述反演结果与区域应变计算获得的龙门山断裂带中北段整体应变积累速率较低、南段应变积累速率较高相一致,均表明中北段闭锁程度高、南段闭锁程度稍低,该特征可以较好地解释汶川地震时从震中向北东向单向破裂现象.