多维观测的矩阵参数建模与加权最小二乘估计     

刘志平  朱丹彤  余航  李思达 《大地测量与地球动力学》2018,38(8):862-867

针对常规向量参数法多维观测建模与平差效率低的问题，分析指出多维观测矩阵参数建模条件应满足不同观测维度的参数独立且个数相等特点（简称独立同构特征），进而利用该建模条件、Kronecker积运算性质和加权最小二乘原理提出矩阵参数建模与加权最小二乘估计方法。该方法顾及不同观测维互相关性，增大系数阵稠密度，降低法矩阵阶数，从而有效提高了建模与平差计算效率。空间直线和GPS站坐标时序模型计算结果均表明，向量参数法和矩阵参数法平差结果相同，但后者具有更高的存储与计算效率。  相似文献   

Method for determining weight matrix for resolving three-dimensional surface deformation using Multi-LOS D-InSAR technology     

《International Journal of Applied Earth Observation and Geoinformation》2020

Three-dimensional surface deformation is resolved using deformations obtained from multiple line of sight differential interferometry synthetic aperture radar (multi-LOS D-InSAR). However, the random model is susceptible to both accidental errors (such as errors due to noises) and system errors (such as orbital errors and topographic errors). To solve this problem, we present a weight-determining method based on high-precision global positioning system (GPS) observations. Specifically, the precision of multi-LOS D-InSAR deformation observations is evaluated based on high-precision GPS deformation observations from the same period. Then, by considering the influence of system errors and accidental errors on the deformation of a pixel observed by multi-LOS D-InSAR, a combined fitting model associated with the positions and elevations of a pixel is built. Finally, the precision of deformations from multi-LOS D-InSAR is evaluated pixel-by-pixel by using the built model. As a result, the weights of observations in the model for resolving three-dimensional surface deformation using multi-LOS D-InSAR can be determined. We verify the feasibility and precision of the weight-determining method through a simulation experiment and a real data experiment, respectively. The verification results show that the proposed weight-determining method based on high-precision GPS observations provides higher reliability for the resolved three-dimensional surface deformation.  相似文献   

基于本质矩阵的无人机影像精确匹配     

葛义攀  王晓红 《测绘通报》2020,(8):55

无人机影像以其低成本、获取容易、信息量大等优点得到了广泛的应用。影像匹配是影像数据处理的重要环节，常用影像匹配的方法存在误匹配多或剔除大量正确匹配的问题。LMedS算法比其他稳健方法更严格，"5点算法"得到的本质矩阵可用于匹配点对共面的场景。本文使用LMedS算法结合"5点算法"求解本质矩阵作为剔除误差的模型，同时利用ORB算法提取速度快的特点，构建了一种精准同时兼顾了效率的匹配方法。本文对该算法开展了试验研究，并与其他常规算法进行比较。试验结果表明，本文算法保留的匹配点数数量多，分布较均匀，适用于多种场景，是一种有效、快速精准的影像匹配算法。  相似文献   

非均匀介质全局广义R/T递推传播矩阵法二维SH地震波模拟研究          下载免费PDF全文

刘彬  荣棉水  孙伟家  黄建平  巴振宁 《地球物理学报》2021,64(2):525-536

地球深部圈层及沉积盆地是一种分区非均匀介质系统,其中不规则地层边界(含起伏地表)对地震波的主要特征有显著影响,而地层的随机非均匀性则主要影响地震波的散射和衰减特征.为了精确刻画不规则地层边界对地震波的反射、透射效应以及非均质体散射引起的地震波衰减效应,全局广义R/T递推传播矩阵法(GGRTM)被提出并逐步发展成为继有限元和有限差分方法之后的另一种复杂介质高精度地震波传播半解析求解方法.在已有的此类方法中,不规则边界均匀地层GGRTM法的优势在于对不规则地层边界的反射和透射效应的准确模拟,而非均质地层薄板化GGRTM法则能准确描述非均质体散射对地震波衰减的影响.本文吸收这两种已有方法的优势,提出了一种考虑非均匀介质、不规则边界的全局广义R/T递推传播矩阵混合方法,并将其用于对边界不规则、层内非均质的复杂模型的二维SH波场模拟.随后在本文方法与边界元法对比研究的基础上讨论了方法的模拟精度.研究结果表明本文提出的混合法是一种解决复杂模型高精度地震模拟的有效方法.  相似文献   

Attribute trajectory analysis: a framework to analyse attribute changes using trajectory analysis techniques     

Long Zhang  Nico Van de Weghe 《International journal of geographical information science》2018,32(5):1043-1059

Trajectory analysis has attracted growing attention in the research field of geography. Beyond traditional moving object trajectories, another type of trajectory exists in which the coordinates are object attributes rather than geographical coordinates. In this paper, a framework to analyse these so-called attribute trajectories is proposed that uses four techniques typically employed in the analysis of moving object trajectories: the Reeb graph, the similarity matrix, the convoy and the mega-convoy. The Reeb graph provides the ability to visualise the temporal dynamics of attribute similarities. The similarity matrix is a supplement of the Reeb graph whose purpose is to visualise the pairwise similarities among the attributes. Moreover, the similarity matrix forms a basis for clustering. The convoy highlights objects whose attributes remain similar for a sufficiently long period. The mega-convoy reduces the number of convoys and reveals their evolutionary histories by merging overlapping convoys. A small real-world meteorological dataset is used as an example to illustrate the attribute trajectory analysis framework and the techniques. This paper aims to form a starting point for applying trajectory analysis techniques in many research fields.  相似文献   

Fe同位素的MC-ICP-MS测试方法   总被引：4，自引：0，他引：4  

侯可军  秦燕  李延河 《地球学报》2012,33(6):885-892

过渡族元素同位素研究是新兴的研究领域和国际研究前沿, 是同位素地球化学研究的热点。本研究利用Neptune型多接收等离子质谱(MC-ICP-MS), 采用标准-样品-标准交叉校正和以Cu为内标的方法对仪器的质量歧视进行校正, 对浓度效应、基质效应、干扰元素扣除和测试的长期重现性进行了检验, 建立了高精度的Fe同位素测试技术。这两种校正方法对实验室标准HSP I Fe在一段时间内δ56Fe和δ57Fe的测试结果分别为0.08‰(2SD)和0.14‰(2SD)分析精度达到国际同类实验室水平, 测试结果在误差范围内与文献值完全一致。  相似文献   

新型常压热解离化学电离装置的研制及应用   总被引：1，自引：1，他引：0  

欧阳永中  韩京  鲍廷义  贾滨  李超  汪志成 《岩矿测试》2012,31(1):64-70

为了克服常压热解离化学电离装置(TDCI)热源控制不稳定、背景干扰较大、实验重现性相对较差等问题。文章在前期研究的基础上,分别对仪器各组成部件进行优化和改进,研制出能够根据待测物的热稳定性、极性、挥发性、熔点等性质,能够对仪器的温度、加热时间、加速电压等仪器参数连续、精确可调的新型常压热解电离源实验装置,并进行了优化和表征。与原研制的TDCI实验装置相比,新型TDCI电离装置的高压调节和温度控制的连续性和精确度以及热源的稳定性得到了极大的提高。高压调节的最小刻度从原来的1 V减小到0.1 V,温度控制系统的调控精确由原来的±5℃减小到±1℃。采用新型TDCI-MS技术,在常压和无需样品预处理的条件下,实现了实际样品可乐中痕量兴奋剂可卡因和牛奶中弱极性物质三聚氰胺的快速检测,单个样品检测时间都小于30 s,检出限低,可卡因和三聚氰胺的最低检出限分别为1.12×10^-12 g/mL和2.62×10^-11 g/mL,重现性好,相对标准偏差(RSD)为4.61%~9.80%,优于原TDCI电离装置的检测结果,完全满足实际样品的检测需要。由于其具有独立稳定的加热装置,与表面解吸常压电离源相比,本仪器装置更适于难挥发性化合物的快速分析。  相似文献   

Ability to detect and locate gross errors on DEM matching algorithm     

《International Journal of Digital Earth》2013,6(1):72-82

Abstract

Digital elevation model (DEM) matching techniques have been extended to DEM deformation detection by substituting a robust estimator for the least squares estimator, in which terrain changes are treated as gross errors. However, all existing methods only emphasise their deformation detecting ability, and neglect another important aspect: only when the gross error can be detected and located, can this system be useful. This paper employs the gross error judgement matrix as a tool to make an in-depth analysis of this problem. The theoretical analyses and experimental results show that observations in the DEM matching algorithm in real applications have the ability to detect and locate gross errors. Therefore, treating the terrain changes as gross errors is theoretically feasible, allowing real DEM deformations to be detected by employing a surface matching technique.  相似文献   

稀疏存储的显式有限元三角网格地震波数值模拟及其PML吸收边界条件   总被引：8，自引：7，他引：1       下载免费PDF全文

刘有山  滕吉文  刘少林  徐涛 《地球物理学报》2013,56(9):3085-3099

有限元法是复杂介质地震模拟的有力工具,它能比较客观地反映地震波的传播,比较细致地再现地震图像.但是,为了获得较精确的结果,有限元法模拟地震波的传播需要的网格点数多,具有计算量大和消耗内存多的缺点.针对上述缺点,本文对刚度矩阵采用压缩存储行(CSR)格式,以减少计算量并节省内存;采用集中质量矩阵得到对角的质量矩阵以提高有限元法(显式有限元)的计算效率;时间离散采用保能量的Newmark算法以提高有限元法的计算精度;采用变分形式(弱形式)的PML吸收边界条件对人工截断边界进行处理.通过与高精度的数值方法--谱元法的数值试验的对比表明,上述方法的引入可使有限元法在计算精度和计算效率方面均可取得比较显著的改进.为了获得相当的计算精度,相比于7阶谱元法,显式有限元法需要更精细的网格.然而,显式有限元法的计算速度比前者快近2倍,而内存需求仅为谱元法的1/4~1/6.  相似文献   

Mapping Cyberspace: Visualizing,Analysing and Exploring Virtual Worlds     

《The Cartographic journal》2013,50(2):117-122

Abstract

With the development of computer technologies such as the Internet and reality, the notion of cyberspace has been emerging and it has been increasingly studied by researchers in various disciplines involving the computer sciences, sociology, geography, and cartography. Cybermaps, as special maps for cyberspace, have been produced and used as a tool for understanding various aspects of cyberspace virtual worlds. Virtual worlds can be distinguished in many ways from the physical world we live in. Because of these distinctions, it is a big challenge for cartographers to offer some clarification. This paper addressed various mapping issues such as visualizing, analysing and exploring cyberspace from different aspects.  相似文献