基于改进的向后-向前选择法粗差定位与估值算法     

柴双武  杨晓琴 《大地测量与地球动力学》2019,39(5):538-543

对传统的向后-向前选择法粗差定位方法进行改进，即在原有基础上加入对平差模型的整体检验，计算统计量的相关系数，通过对偏相关系数的检验来定位统计量相关的粗差观测值。通过模拟粗差算例证明，该算法能够准确定位多维粗差，有效改善粗差定位转移的现象，且粗差估值结果比较可靠。  相似文献   

Phase equilibrium modelling of the amphibolite to granulite facies transition in metabasic rocks (Ivrea Zone,NW Italy)     

Barbara E. Kunz  Richard W. White 《Journal of Metamorphic Geology》2019,37(7):935-950

The development of thermodynamic models for tonalitic melt and the updated clinopyroxene and amphibole models now allow the use of phase equilibrium modelling to estimate P–T conditions and melt production for anatectic mafic and intermediate rock types at high‐T conditions. The Permian mid‐lower crustal section of the Ivrea Zone preserves a metamorphic field gradient from mid amphibolite facies to granulite facies, and thus records the onset of partial melting in metabasic rocks. Interlayered metabasic and metapelitic rocks allows the direct comparison of P–T estimates and partial melting between both rock types with the same metamorphic evolution. Pseudosections for metabasic compositions calculated in the Na₂O–CaO–K₂O–FeO–MgO–Al₂O₃–SiO₂–H₂O–TiO₂–O (NCKFMASHTO) system are presented and compared with those of metapelitic rocks calculated with consistent end‐member data and a–x models. The results presented in this study show that P–T conditions obtained by phase equilibria modelling of both metabasic and metapelitic rocks give consistent results within uncertainties, allowing integration of results obtained for both rock types. In combination, the calculations for both metabasic and metapelitic rocks allows an updated and more precisely constrained metamorphic field gradient for Val Strona di Omegna to be defined. The new field gradient has a slightly lower dP/dT which is in better agreement with the onset of crustal thinning of the Adriatic margin during the Permian inferred in recent studies.  相似文献   

非等间距GM(1,1)模型的总体最小二乘算法及其病态问题     

陶武勇  花向红  鲁铁定  陈西江  张伟 《大地测量与地球动力学》2019,39(1):45-50

在非等间距GM(1,1)模型中，系数矩阵中有无误差的常数项和有误差的随机项，并且系数矩阵与观测向量误差同源，即系数矩阵与观测向量中有相同的元素存在，这些相同元素应该有相同的改正数，为此本文推导了一种适合非等间距GM(1,1)模型求解的总体最小二乘算法。同时，考虑到非等间距GM(1,1)模型中存在病态问题时影响总体最小二乘计算结果的稳定性，提出对系数矩阵常数列乘以某一常数的方法，以改善病态问题。  相似文献   

不等式约束Partial EIV模型的WHP拟牛顿修正解法及其精度评定的SUT法     

王乐洋  邹传义  吴璐璐 《大地测量与地球动力学》2019,39(6):648-653

提出一种确定不等式约束Partial EIV模型解及精度评定的新方法，在总体最小二乘准则下，将附有不等式约束的Partial EIV模型转换为标准最优化问题。采取WHP拟牛顿修正的SQP方法求解，并利用SUT法对参数估值进行精度评定，可以减小迭代次数、提高收敛速度，且精度评定方法简单有效。  相似文献   

加权EIV模型的经典最小二乘算法     

谢建  龙四春 《大地测量与地球动力学》2019,39(5):544-546

采用GHM方法将EIV模型在最优解处线性化，得到解的近似方差。然后，将EIV模型表达成与Gauss-Markov模型相似的形式，利用标准最小二乘理论推导EIV模型的解及近似方差矩阵，得到与已有算法等价的结论。最后，推导观测值估值和残差的统计性质，建立起一整套EIV模型参数估计和精度评定的体系。  相似文献   

New constraints on granulite facies metamorphism and melt production in the Lewisian Complex,northwest Scotland          下载免费PDF全文

Yves Feisel  Richard W. White  Richard M. Palin  Tim E. Johnson 《Journal of Metamorphic Geology》2018,36(6):799-819

In this study, we investigate the metamorphic history of the Assynt and Gruinard blocks of the Archean Lewisian Complex, northwest Scotland, which are considered by some to represent discrete crustal terranes. For samples of mafic and intermediate rocks, phase diagrams were constructed in the Na₂O–CaO–K₂O–FeO–MgO–Al₂O₃–SiO₂–H₂O–TiO₂–O₂ (NCKFMASHTO) system using whole‐rock compositions. Our results indicate that all samples equilibrated at similar peak metamorphic conditions of ~8–10 kbar and ~900–1,000°C, consistent with field evidence for in situ partial melting and the classic interpretation of the central region of the Lewisian Complex as representing a single crustal block. Melt‐reintegration modelling was employed in order to estimate probable protolith compositions. Phase equilibria calculated for these modelled undepleted precursors match well with those determined for a subsolidus amphibolite from Gairloch in the southern region of the Lewisian Complex. Both subsolidus lithologies exhibit similar phase relations and potential melt fertility, with both expected to produce orthopyroxene‐bearing hornblende granulites, with or without garnet, at the conditions inferred for the Badcallian metamorphic peak. For fully hydrated protoliths, prograde melting is predicted to first occur at ~620°C and ~9.5 kbar, with up to 45% partial melt predicted to form at peak conditions in a closed‐system environment. Partial melts calculated for both compositions between 610 and 1,050°C are mostly trondhjemitic. Although the melt‐reintegrated granulite is predicted to produce more potassic (granitic) melts at ~700–900°C, the modelled melts are consistent with the measured compositions of felsic sheets from the central region Lewisian Complex.  相似文献   

稳健的回光反射平面靶心定位算法     

付永健  李宗春  何华 《地球信息科学学报》2018,20(4):422-429

针对因回光反射平面标靶点云数据缺失或冗余而难以准确计算靶心坐标的问题,本文提出一种基于距离标靶重心最远点的边缘点提取和靶心定位算法。首先,进行点云数据预处理,先人工大概选取出标靶点云所在位置,并根据回光反射强度信息提取出标靶点云,对标靶点云进行粗差剔除、投影以及坐标旋转等工作;然后,进行边缘点提取,应用所提的边缘点提取算法对投影到二维平面的标靶点云进行边缘点提取;最后,进行靶心定位,先应用抗差最小二乘对边缘点进行拟合计算圆心坐标,然后将其旋转回三维空间作为靶心坐标计算值。实验结果表明,本文提出的边缘点提取算法能高效、准确地提取出标靶边缘点,比文献[12]中的边缘点提取算法节约了大量时间,并且应用所提取出的边缘点能稳健地计算出靶心坐标,与基准值的偏差在亚毫米以内,优于文献[11]、[12]算法靶心计算精度,有效地解决了残缺或冗余的回光反射平面标靶点云靶心定位问题。  相似文献   

二次曲面与最小二乘配置的组合模型在GPS高程异常拟合中的应用     

吕建伟  张志华  张新秀  刘祖昱 《测绘通报》2020,(5):127

在工程实践应用中，为了有效利用GPS高程数据，减少对传统水准测量的依赖，提高GPS高程异常的拟合精度便显得十分重要。为此，本文在介绍二次曲面拟合和最小二乘配置拟合基本原理分析、算法过程推导的基础上，提出了一种新的高程异常拟合方法。首先在二次曲面拟合的基础上，计算得到原始观测数据与拟合数据之间的残差序列，然后采用最小二乘配置模型对包括二次曲面拟合模型误差的综合误差进行优化减弱，最后得到新的高程异常。通过实例，将二次曲面拟合法，最小二乘配置法与文中提出的新方法进行比较分析。结果表明：新的组合方法的拟合预测精度要明显优于最小二乘配置及二次曲面拟合。  相似文献   

A New Retracking Technique for Brown Peaky Altimetric Waveforms     

Fukai Peng 《Marine Geodesy》2018,41(2):99-125

A new Brown-Peaky (BP) retracker has been developed for peaky waveforms that usually appear within ～10 km to the coastline. The main feature of the BP is that it fits peaky waveforms using the Brown model without introducing a peak function. The retracking strategy first detects the peak location and width of a waveform using an adaptive peak detection method, and then estimates retracking parameters using a weighted least squares (WLS) estimator. The WLS assigns a downsized weight to corrupted waveform gates, but an equal weight to other normal waveform gates. The BP retracker has been applied to 4-year Jason-1 waveform (2002–2006) in two Australian coastal zones. The results retracked by BP, MLE4 and ALES retrackers have been validated against tide-gauge observations located at Burnie, Lorne and Broome. The comparison results show that three retrackers have similar performance over open oceans with the correlation coefficient (～0.7) and RMSE (～13 cm) between altimetric and tide-gauge sea levels for distance >7 km offshore. The main improvement of BP retracker occurs for distance ≤7 km to the coastline, where validation results indicate that data retracked by BP are more accurate (15–21 cm) than those by ALES (16–24 cm) and MLE4 (19–37 cm).  相似文献   

杭州湾中部实测波浪特性分析   总被引：1，自引：0，他引：1  

杨斌  杨忠良  叶钦  张俊彪  施伟勇 《海洋工程》2018,36(3):96-103

利用杭州湾中部一年实测波浪资料,分析该地区的波参数统计变化特性,采用最小二乘法拟合得出相关参数之间的关系式,并统计分析了频谱特性。结果表明:杭州湾中部以小浪和轻浪为主,在各月分布较为均匀,年平均周期为2.97 s;最大一次波浪过程为冷空气影响所致,影响强度大于台风莫拉克;常浪向分布在东北至东南向,其中又以小浪出现较多,对应的波周期以2~4 s为主;强浪向主要分布在西北和东北方向,对应的波周期主要分布在3~5 s;多数特征波参数之间相关关系较好;由谱分析得知风浪占多数,且以单峰为主。研究结果可为相关工程和理论研究提供基础资料。  相似文献