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A flexible lag definition for experimental variogram calculation 被引量:3
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作者 Cuba Miguel 《Mining Science and Technology》 EI CAS 2011年第2期207-211,共5页
Inferring the experimental variogram used in geostatistics commonly relies on the method-of-moments approach.Ideally,the available data-set used for calculating the experimental variogram should be drawn from a regula... Inferring the experimental variogram used in geostatistics commonly relies on the method-of-moments approach.Ideally,the available data-set used for calculating the experimental variogram should be drawn from a regular pattern.However,in practice the available data-set is typically sampled over a sparse pattern at irregularly spaced locations.Hence,some binning of the variogram cloud is required to obtain fair estimates of the experimental variogram.Grouping of the variogram data pairs as a result of conventional binning depends on parameters such as the main anisotropic directions and a regular definition of the lag vectors.These parameters are not based on the configuration of the variogram data pairs in the variogram cloud but on a segment of it that is arbitrarily predefined.Therefore,the conventional experimental variogram estimation approach is biased because of the strict configuration of the bins over the variogram cloud.In this paper,a new method of estimating experimental variograms is proposed.Lag vectors and their tolerances are decided in the proposed method from information in the variogram cloud:they are not influenced by any predefined directions.The proposed methodology is a well-founded,practicable and easy-to-automate approach for experimental variogram calculation using an irregularly sampled data-set.Comparison of results from the new method to those from the traditional approach is very encouraging. 展开更多
关键词 GEOSTATISTICS variogram cloud Experimental variogram variogram modeling Self-organizing-map
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VARIOGRAM无偏估计类探讨
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作者 陈励 《云南师范大学学报(自然科学版)》 2000年第6期1-5,共5页
Variogram是空间数据分析中的一个重要参数。本文给出了 VARIOGRAM的一个无偏估计类。用之和传统估计作比较 。
关键词 variogram 无偏估计类 方差 数理统计
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Characterizing Landscape Spatial Heterogeneity in Multisensor Images with Variogram Models
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作者 QIU Bingwen ZENG Canying +3 位作者 CHENG Chongcheng TANG Zhenghong GAO Jianyang SUI Yinpo 《Chinese Geographical Science》 SCIE CSCD 2014年第3期317-327,共11页
Most evaluation of the consistency of multisensor images have focused on Normalized Difference Vegetation Index (NDVI) products for natural landscapes, often neglecting less vegetated urban landscapes. This gap has ... Most evaluation of the consistency of multisensor images have focused on Normalized Difference Vegetation Index (NDVI) products for natural landscapes, often neglecting less vegetated urban landscapes. This gap has been filled through quantifying and evaluating spatial heterogeneity of urban and natural landscapes from QuickBird, Satellite pour l'observation de la Terre (SPOT), Ad- vanced Spacebome Thermal Emission and Reflection Radiometer (ASTER) and Landsat Thematic Mapper (TM) images with variogram analysis. Instead of a logarithmic relationship with pixel size observed in the corresponding aggregated images, the spatial variability decayed and the spatial structures decomposed more slowly and complexly with spatial resolution for real multisensor im- ages. As the spatial resolution increased, the proportion of spatial variability of the smaller spatial structure decreased quickly and only a larger spatial structure was observed at very coarse scales. Compared with visible band, greater spatial variability was observed in near infrared band for both densely and less densely vegetated landscapes. The influence of image size on spatial heterogeneity was highly dependent on whether the empirical sernivariogram reached its sill within the original image size. When the empirical semivariogram did not reach its sill at the original observation scale, spatial variability and mean characteristic length scale would increase with image size; otherwise they might decrease. This study could provide new insights into the knowledge of spatial heterogeneity in real multisen- sor images with consideration of their nominal spatial resolution, image size and spectral bands. 展开更多
关键词 variogram modeling spatial heterogeneity characteristic scale multisensor image
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A Method to Integrate Geological Knowledge in Variogram Modeling of Facies: A Case Study of a Fluvial Deltaic Reservoir
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作者 Margaret Akoth Oloo Congjiao Xie 《International Journal of Geosciences》 2018年第6期337-353,共17页
Variograms are important tools in the spatial distribution of facies and petrophysical properties. Due to the scarcity of subsurface well data, both spatially and quantity wise, variograms representing the data tend t... Variograms are important tools in the spatial distribution of facies and petrophysical properties. Due to the scarcity of subsurface well data, both spatially and quantity wise, variograms representing the data tend to have a lot of uncertainties. In order to reduce uncertainty in variograms, well data can be supplemented with the geological knowledge of the reservoir. This has been demonstrated by various authors in previous works. In their paper “Methodology to Incorporate Geological Knowledge in Variogram Modeling,” A. Bahar and M. Kelkar introduced a methodology to incorporate geological knowledge by studying the energy level of the depositional environment and grain texture. They used these two attributes to determine the relative distance of continuity of the lithofacies and incorporated it in the variogram modeling. In this paper, we introduce another attribute that determines the continuity of lithofacies;the accommodation or deposition space. For illustration purpose, two sets of facies models were constructed: The first using subsurface well data only and the second using well data and geological information of the reservoir. The two sets of models showed significant variation in the property distribution. The first set gave a more random appearance of the facies distribution while the second set gave a more realistic depiction of the depositional environment of the reservoir. We concluded that other than the grain size and the energy level of the depositional environment, another important determinant for continuity in variograms is the knowledge of the depositional space. Incorporating the knowledge of the depositional environment enabled a more accurate estimation of the variogram parameters. This resulted in an improvement in the accuracy of the model. 展开更多
关键词 Geological Knowledge DEPOSITIONAL Environment Energy Level variogram
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ENHANCING GROUND RESOLUTION OF TM6 BASED ON MULTI-VARIATE REGRESSION MODEL AND SEMI-VARIOGRAM FUNCTION
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作者 MA Hongchao LI Deren 《Geo-Spatial Information Science》 2001年第1期43-49,共7页
It is well known that Landsat TM images are the most widely used remote sensing data in various fields.Usually,it has 7 different electromagnetic spectrum bands,among which the sixth one has much lower ground resoluti... It is well known that Landsat TM images are the most widely used remote sensing data in various fields.Usually,it has 7 different electromagnetic spectrum bands,among which the sixth one has much lower ground resolution compared with the other six bands.Nevertheless,it is useful in the study of rock spectrum reflection,geothermal resources exploration,etc.To improve the ground resolution of TM6 to the level as that of the other six bands is a problem .This paper presents an algorithm based on the combination of multivariate regression model with semivariogram function which can improve the ground resolution of TM6 by "fusing" the data of other six bands.It includes the following main steps: (1) testing the correlation between TM6 and one of TM15,7.If the correlation coefficient between TM6 and another one is greater than a given threshold value,then select the band to the regression analysis as an argument.(2) calculating the size of the template window within which some parameters needed by the regression model will be calculated; (3) replacing the original pixel values of TM6 by those obtained by regression analysis; (4) using image entropy as a measurement to evaluate the quality of the fused image of TM6.The basic mechanism of the algorithm is discussed and the V C ++ program for implementing this algorithm is also presented.A simple application example is given in the last part of this paper,showing the effectiveness of the algorithm. 展开更多
关键词 multi-variate regression model semi-variogram FUNCTION image fusion TEMPLATE WINDOW V C++ PROGRAMMING
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Variogram Analyses of Soil Characters in Glacial Moraine Landscapes
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作者 Adzemi Mat Arshad Mustika Edi Armanto +1 位作者 Juergen Lamp Elisa Wildayana 《Journal of Environmental Science and Engineering(A)》 2012年第12期1308-1316,共9页
The objective of this research is to analyze variogram analyses of soil characters in Glacial Moraine Landscapes. The research site is located in sloping landscapes, Kuehren, North Germany. The survey method was detai... The objective of this research is to analyze variogram analyses of soil characters in Glacial Moraine Landscapes. The research site is located in sloping landscapes, Kuehren, North Germany. The survey method was detailed using maps with scales of 1:5,000. Soil sampling was performed by soil pits and borings and completely analyzed in laboratory. Collected data were evaluated by geostatistics program for spatial soil variability analyses. The variogram models show that spatial soil variability ranges between 70-120 m (mean: 85 m). Effective distances of sampling are calculated at around 50 m. The range values of soil characters are proportional with the range of elevation (range: 70 m, effective distance: 40 m). The relief determines mainly the spatial variability of soil characters. 展开更多
关键词 variogram analyses soil characters glacial moraine landscapes
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Imaging Analysis of Trabecular Bone Texture Based on the Initial Slope of Variogram of Ultra-Distal Radius Digital X-Ray Imaging: Effects on Bone Mineral Density and Age
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作者 Jianfeng Chen Qifeng Ying 《Open Journal of Radiology》 2022年第3期78-85,共8页
Background: When applied to trabecular bone X-ray images, a method for analyzing trabecular bone texture based on the initial slope of variogram (ISV) was used to assess the trabecular bone health. Methodology: Data f... Background: When applied to trabecular bone X-ray images, a method for analyzing trabecular bone texture based on the initial slope of variogram (ISV) was used to assess the trabecular bone health. Methodology: Data from more than two hundred subjects were retrospectively studied. For each subject, a DXA (GE Lunar Prodigy) scan of the forearm was performed, and bone mineral density (BMD) value was measured at the location of ultra-distal radius, X-ray digital image of the same forearm was taken on the same day, and ISV value over the same location of ultra-distal radius was calculated. Pearson’s correlation coefficients were calculated to examine the correlation between BMD and ISV of the trabecular bones located at the same ultra-distal radius. ISV values changed with subjects’ age were also reported. Results: The results show that ISV value was highly correlated with the DXA-measured BMD of the same trabecular bone located at the ultra-distal radius. The correlation coefficient between ISV and BMD with the 95% confident was 0.79 ± 0.09. They also demonstrated that the age-related changes in trabecular bone health and differentiated age patterns in males and females, respectively. The results showed that the decrease in BMD was accompanied by a decrease in the initial slope of variogram (ISV). Conclusions: This study suggests that ISV might be used to quantitatively evaluate trabecular health for osteoporosis and bone disease diagnosis. 展开更多
关键词 Trabecular Bone Texture Digital X-Ray Image Bone Mineral Density Ultra-Distal Radius Initial Slope of variogram
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Applications of variogram modeling to electrical resistivity data for the occurrence and distribution of saline groundwater in Domail Plain,northwestern Himalayan fold and thrust belt,Pakistan
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作者 Asam FARID Perviez KHALID +2 位作者 Khan Zaib JADOON Muhammad Asim IQBAL Muhammad SHAFIQUE 《Journal of Mountain Science》 SCIE CSCD 2017年第1期158-174,共17页
This paper studies electrical resistivity dataset acquired for a groundwater study in the Domail Plain in the northwestern Himalayan section of Pakistan. Through a combination of geostatistical analysis,geophysical in... This paper studies electrical resistivity dataset acquired for a groundwater study in the Domail Plain in the northwestern Himalayan section of Pakistan. Through a combination of geostatistical analysis,geophysical inversion and visualization techniques,it is possible to re-model and visualize the single dimension resistivity data into 2D and 3D space.The variogram models are utilized to extend the interpretation of the data and to distinguish individual lithologic units and the occurrence of saline water within the subsurface. The resistivity data has been calibrated with the lithological logs taken from the available boreholes. As such the alluvial system of the Domail Plain has formed during episodes of local tectonic activity with fluvial erosion and depositionyielding coarse sediments with high electrical resistivities near to the mountain ranges and finer sediments with medium to low electrical resistivities which tend to settle in the basin center. Thus a change is depositional setting happened from basin lacustrine environment to flash flooding during the Himalayan orogeny. The occurrence of rock salt in the northern mountains has imparted a great influence on the groundwater quality of the study area. The salt is dissolved by water which infiltrates into the subsurface through the water channels. Variogram aided gridding of resistivity data helps to identify the occurrence and distribution of saline water in the subsurface. 展开更多
关键词 Inversion Domail Resistivity variogram Gridding
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A Yield Mapping Procedure Based on Robust Fitting Paraboloid Cones on Moving Elliptical Neighborhoods and the Determination of Their Size Using a Robust Variogram
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作者 Martin Bachmaier 《Positioning》 2010年第1期27-41,共15页
The yield map is generated by fitting the yield surface shape of yield monitor data mainly using paraboloid cones on floating neighborhoods. Each yield map value is determined by the fit of such a cone on an elliptica... The yield map is generated by fitting the yield surface shape of yield monitor data mainly using paraboloid cones on floating neighborhoods. Each yield map value is determined by the fit of such a cone on an elliptical neighborhood that is wider across the harvest tracks than it is along them. The coefficients of regression for modeling the paraboloid cones and the scale parameter are estimated using robust weighted M-estimators where the weights decrease quadratically from 1 in the middle to zero at the border of the selected neighborhood. The robust way of estimating the model parameters supersedes a procedure for detecting outliers. For a given neighborhood shape, this yield mapping method is implemented by the Fortran program paraboloidmapping.exe, which can be downloaded from the web. The size of the selected neighborhood is considered appropriate if the variance of the yield map values equals the variance of the true yields, which is the difference between the variance of the raw yield data and the error variance of the yield monitor. It is estimated using a robust variogram on data that have not had the trend removed. 展开更多
关键词 Precision Agriculture Yield Mapping GPS Elliptical Neighborhood PARABOLOID Weighted Regression Redescending M-estimate Robust variogram
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Down-scaling LUCC based on the histo-variogram 被引量:3
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作者 ZHANG Hao CAO ChunXiang +3 位作者 LI GuoPing YANG Hua LI XiaoWen QIN Jun 《Science China(Technological Sciences)》 SCIE EI CAS 2009年第5期1348-1353,共6页
In remote sensing applications,accurate extraction of land type area after classification is very impor-tant.But for images of land use/cover change(LUCC) obtained from the special spatial resolution re-mote sensing d... In remote sensing applications,accurate extraction of land type area after classification is very impor-tant.But for images of land use/cover change(LUCC) obtained from the special spatial resolution re-mote sensing data,it will be of great significance to obtain the land type area information with higher resolution by making use of spatial distribution characteristcs information of the land type itself first and further scaling-down in a given scale threshold on the basis of the existing spatial resolution data.An explicit expression of the relationship between the measurement scale,global fractal dimension and the land type area corresponding to different measurement scales is obtained on the research basis of the authors' histo-variogram using the standardized area index(SAI).A good attempt has been made to obtain the land type area information with higher resolution by merely using the spatial distribution characteristcs information of the land type in the image itself and further scaling-down in a given scale threshold on the basis of the existing spatial resolution data. 展开更多
关键词 histo-variogram scaling-down scale effect LUCC
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Analysis of variograms with various sample sizes from a multispectral image 被引量:1
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作者 Huihui Zhang Yubin Lan +4 位作者 Ronald E.Lacey Yanbo Huang W.Clint Hoffmann D.Martin G.C.Bora 《International Journal of Agricultural and Biological Engineering》 SCIE EI CAS 2009年第4期62-69,共8页
Variogram plays a crucial role in remote sensing application and geostatistics.It is very important to estimate variogram reliably from sufficient data.In this study,the analysis of variograms computed on various samp... Variogram plays a crucial role in remote sensing application and geostatistics.It is very important to estimate variogram reliably from sufficient data.In this study,the analysis of variograms computed on various sample sizes of remotely sensed data was conducted.A 100×100-pixel subset was chosen randomly from an aerial multispectral image which contains three wavebands,Green,Red and near-infrared(NIR).Green,Red,NIR and Normalized Difference Vegetation Index(NDVI)datasets were imported into R software for spatial analysis.Variograms of these four full image datasets and sub-samples with simple random sampling method were investigated.In this case,half size of the subset image data was enough to reliably estimate the variograms for NIR and Red wavebands.To map the variation on NDVI within the weed field,ground sampling interval should be smaller than 12 m.The information will be particularly important for Kriging and also give a good guide of field sampling on the weed field in the future study. 展开更多
关键词 variogram multispectral image GEOSTATISTICS
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河流床面粗糙程度的度量方法研究 被引量:1
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作者 祁芸泉 蔡暾 杨克君 《水利水电技术(中英文)》 北大核心 2024年第1期103-112,共10页
【目的】河流床面的粗糙程度是河流动力学中重要的研究内容。【方法】用统计分析法来量化河流床面的粗糙程度,在不考虑河床宏观起伏的前提下,用非均匀天然沙人工铺制初始粗糙床面,并逐渐增大流量使床面粗化,粗化完成后依托激光扫描技术... 【目的】河流床面的粗糙程度是河流动力学中重要的研究内容。【方法】用统计分析法来量化河流床面的粗糙程度,在不考虑河床宏观起伏的前提下,用非均匀天然沙人工铺制初始粗糙床面,并逐渐增大流量使床面粗化,粗化完成后依托激光扫描技术获得试验床面的精确数字高程。基于统计理论探究在不同来水条件下,粗化后河流床面表层的结构特性并利用床面高程统计参数及变异函数满足的理论模型建立新的床面粗糙程度度量方法。【结果】结果显示:曼宁糙率n与中值粒径的拟合关系一般,相关系数为0.649。n与标准差、众数及偏度拟合关系良好,与峰度拟合关系相对较差。n与三种变异函数球状模型典型参数都呈现出较好的相关性,剖面平均变异函数块金值与基台值和n的拟合关系优秀,相关系数均在0.89以上。【结论】结果表明:代表粒径法在某些时刻是可以用于表述床面粗糙特性的,高程数据的标准差随水流强度的增加而严格增大的特性和其众数随水流结构的增大而严格减小的特性使它们成为量化床面粗糙程度的优良指标。偏度和峰度的单调趋势使其作为床面粗糙程度的衡量指标也成为可能。块金值与基台值可以作为床面粗糙程度的表征指标。此次研究用统计法探讨了度量河流床面粗糙程度的方法,对粗糙程度的度量有一定启示。 展开更多
关键词 床面粗糙程度 统计参数 曼宁糙率 变异函数 球状模型 水力特性
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基于深度学习的变差函数自动拟合方法研究
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作者 赵丽芳 喻思羽 李少华 《物探与化探》 CAS 2024年第5期1359-1367,共9页
变差函数是量化空间相关性的重要工具,现有变差函数拟合方法存在拟合结果不稳定现象。针对现有方法的不足,本文提出一种基于深度学习的变差函数自动拟合方法,以提高自动拟合的精度与稳定性。实验变差函数的拟合本质是一种非线性优化问题... 变差函数是量化空间相关性的重要工具,现有变差函数拟合方法存在拟合结果不稳定现象。针对现有方法的不足,本文提出一种基于深度学习的变差函数自动拟合方法,以提高自动拟合的精度与稳定性。实验变差函数的拟合本质是一种非线性优化问题,即实现实验变差函数与理论变差函数之间的匹配度最优化。新方法采用多组参数值不同的理论变差函数生成大量训练数据集并进行深度神经网络训练学习,最后采用训练模型完成实验变差函数自动拟合。多组实验结果表明,基于深度神经网络的强大拟合能力,新方法拟合稳定性、计算效率均优于最小二乘法,为地质统计学中变差函数自动拟合提供了新思路。 展开更多
关键词 变差函数 自动拟合 深度学习 地质统计学
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考虑地震事件内空间相关性的区域概率地震危险性分析
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作者 丁佳伟 吕大刚 曹正罡 《工程力学》 EI CSCD 北大核心 2024年第S01期117-128,共12页
一次地震事件不同地点的地震动强度参数与结构响应参数之间是空间相关的,相关的地震效应将导致地震损失急剧集中与积累,从而造成灾难性事件,但是现有的区域尺度地震风险评估并没有考虑地震动的空间相关性。该文采用地统计学方法表征地... 一次地震事件不同地点的地震动强度参数与结构响应参数之间是空间相关的,相关的地震效应将导致地震损失急剧集中与积累,从而造成灾难性事件,但是现有的区域尺度地震风险评估并没有考虑地震动的空间相关性。该文采用地统计学方法表征地震事件内地震动强度参数的空间相关性,提出了理论半变异函数的几何稳健估计方法,并采用加权最小二乘法实现对短距离空间相关性的准确高效评估。以新潟越冲地震为例,基于指数半变异函数模型,采用加权最小二乘法对几何稳健估计半变异函数值进行拟合,得到了PGA、PGV和0 s~10 s谱加速度的空间相关性函数,提出了变程b值的预测模型,结果表明:相比于短周期谱加速度,长周期谱加速度的空间相关性衰减速率更小,且在T=0.45 s处存在拐点。将所开发的空间相关性模型应用于区域概率地震危险性分析,采用Monte Carlo方法实现了空间相关随机场的区域地震动强度参数的模拟,改进了传统区域地震危险性分析的方法,发现绝大多数情况下考虑空间相关性的年超越概率大于未考虑空间相关性的年超越概率,表明考虑空间相关性对于建筑群落及基础设施风险评估、韧性城市建设等具有重要的指导意义。 展开更多
关键词 事件内残差 空间相关性 几何稳健估计 加权最小二乘法 半变异函数 区域危险性分析
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基于最小数据集的三江平原黑土地土壤质量评价——以黑龙江宝清县平原区为例
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作者 何金宝 赵建 +2 位作者 刘洪博 刘博文 孔繁鹏 《地质通报》 CAS CSCD 北大核心 2024年第10期1841-1854,共14页
土壤质量评价是实施精细化农业生产和土地科学管理的关键。对不同土地利用方式下的土壤质量进行评估并对其空间分布进行绘制,可以为优化土地利用空间布局,客观准确评价土壤质量和科学管理土地资源提供依据。以黑龙江宝清县平原区黑土地... 土壤质量评价是实施精细化农业生产和土地科学管理的关键。对不同土地利用方式下的土壤质量进行评估并对其空间分布进行绘制,可以为优化土地利用空间布局,客观准确评价土壤质量和科学管理土地资源提供依据。以黑龙江宝清县平原区黑土地土壤为研究对象,综合选取31项评价指标作为全数据集(TDS),采用主成分分析(PCA)和相关性分析方法,确定不同土地利用类型的土壤质量评价的最小数据集(MDS)。利用地统计学方法,基于普通克里格插值法绘制土壤质量的空间分布图。结果表明,不同土地利用方式下的土壤质量存在明显差异,土壤质量整体表现为,草地>林地>旱地>水田。半变异函数为高斯函数的模型最适合预测土壤质量的空间分布。土壤质量在空间分布上呈现一定的规律性,越靠近北部挠力河流域,质量越好,大部分土壤质量处于中上水平,生产潜力较大。 展开更多
关键词 黑土地 土地利用类型 最小数据集 地统计学 半变异函数
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Key parameter optimization and analysis of stochastic seismic inversion 被引量:11
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作者 黄哲远 甘利灯 +2 位作者 戴晓峰 李凌高 王军 《Applied Geophysics》 SCIE CSCD 2012年第1期49-56,115,116,共10页
Stochastic seismic inversion is the combination of geostatistics and seismic inversion technology which integrates information from seismic records, well logs, and geostatistics into a posterior probability density fu... Stochastic seismic inversion is the combination of geostatistics and seismic inversion technology which integrates information from seismic records, well logs, and geostatistics into a posterior probability density function (PDF) of subsurface models. The Markov chain Monte Carlo (MCMC) method is used to sample the posterior PDF and the subsurface model characteristics can be inferred by analyzing a set of the posterior PDF samples. In this paper, we first introduce the stochastic seismic inversion theory, discuss and analyze the four key parameters: seismic data signal-to-noise ratio (S/N), variogram, the posterior PDF sample number, and well density, and propose the optimum selection of these parameters. The analysis results show that seismic data S/N adjusts the compromise between the influence of the seismic data and geostatistics on the inversion results, the variogram controls the smoothness of the inversion results, the posterior PDF sample number determines the reliability of the statistical characteristics derived from the samples, and well density influences the inversion uncertainty. Finally, the comparison between the stochastic seismic inversion and the deterministic model based seismic inversion indicates that the stochastic seismic inversion can provide more reliable information of the subsurface character. 展开更多
关键词 stochastic seismic inversion signal-to-noise ratio variogram posterior probability distribution sample number well density
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北京市近郊区土壤镍的空间结构及分布特征 被引量:75
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作者 郑袁明 陈同斌 +4 位作者 陈煌 吴泓涛 周建利 罗金发 黄泽春 《地理学报》 EI CSCD 北大核心 2003年第3期470-476,共7页
通过对北京市近郊区349处土壤的取样调查,利用地统计学方法研究了北京市土壤中镍的空间结构和分布特征。结果显示,镍的空间结构性较好,具有明显的可迁性特点,块金效应所占的比例较大;实验变异函数可用指数模型拟合,利用所得模型进行克... 通过对北京市近郊区349处土壤的取样调查,利用地统计学方法研究了北京市土壤中镍的空间结构和分布特征。结果显示,镍的空间结构性较好,具有明显的可迁性特点,块金效应所占的比例较大;实验变异函数可用指数模型拟合,利用所得模型进行克立格插值得到土壤镍含量的分布图,发现北京市土壤中,镍的含量分布具有明显的西北低而东南高的趋势。与北京市土壤镍含量的背景值进行对比,全市土壤并不存在非常严重的镍污染,其空间分布主要受成土母质制约;但是人类活动、风向、河流等人文和自然条件对镍的空间结构和分布格局也有一定程度的影响。 展开更多
关键词 土壤 空间结构 地统计学 变异函数 克立格插值
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珠三角区域PM_(2.5)时空变异特征 被引量:64
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作者 徐伟嘉 何芳芳 +1 位作者 李红霞 钟流举 《环境科学研究》 EI CAS CSSCI CSCD 北大核心 2014年第9期951-957,共7页
珠三角区域PM2.5污染严重,以2012年9月─2013年8月62个大气监测站的PM2.5联网数据为基础,采用地统计学方法定性、定量分析了该区域ρ(PM2.5)的时空变异特征.定性分析结果表明,基底效应在0.12~0.30之间,相应ρ(PM2.5)变异属于以结构性... 珠三角区域PM2.5污染严重,以2012年9月─2013年8月62个大气监测站的PM2.5联网数据为基础,采用地统计学方法定性、定量分析了该区域ρ(PM2.5)的时空变异特征.定性分析结果表明,基底效应在0.12~0.30之间,相应ρ(PM2.5)变异属于以结构性变异为主的Ⅰ、Ⅱ类,对应的空间自相关程度为强、较强,说明珠三角区域的ρ(PM2.5)分布差异主要由区域结构所致.定量分析结果表明:1空间自相关距离受气象因素影响,随方向和时间在51~85 km之间变化,东西方向的影响距离(75~85 km)最大.2ρ(PM2.5)在南北方向的变异幅度指数(0.34~0.70)和变异速度指数〔0.14~0.38μg(m3·km)〕在各方向中均为最大;而东北─西南方向的2个指标则均为最小,其中变异幅度指数为0.25~0.42,变异速度指数在0.13~0.34μg(m3·km)之间,即南北方向的ρ(PM2.5)变化大于其他方向.3综合异质指数介于0.14~0.54之间,说明ρ(PM2.5)总体保持在中等异质水平.鉴于珠三角区域ρ(PM2.5)的空间变异特征,在进行监测站布设时,矩形网格相较于方形网格更适合于对该区域地理空间进行划分,其中网格的长为东西方向平均空间自相关距离(78 km)的2倍,宽为南北方向平均空间自相关距离(56 km)的2倍. 展开更多
关键词 PM2.5 时空变异 变差函数 地统计学 异质性
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长江水系沉积物重金属含量空间分布特征研究——地统计学方法 被引量:183
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作者 张朝生 章申 何建邦 《地理学报》 EI CSSCI CSCD 北大核心 1997年第2期184-192,共9页
本文利用地统计学方法研究了长江水系沉积物11种重金属元素含量的空间分布特征。采用变异函数定量描述空间分布结构特征和克立格法进行最优插值,并制作出含量分布图。结果表明:所研究的重金属在长江水系沉积物中均有显著的空间结构... 本文利用地统计学方法研究了长江水系沉积物11种重金属元素含量的空间分布特征。采用变异函数定量描述空间分布结构特征和克立格法进行最优插值,并制作出含量分布图。结果表明:所研究的重金属在长江水系沉积物中均有显著的空间结构性特点,其变异函数均可用有块金效应的球状模型进行拟合。多数元素变异函数的变程在1000km左右,这种长距离的变程与分布图上同性质斑块平均距离相当。在约500km以上,多数元素的变异函数表现出一定的方向性特点,大多在NE~SW或NW~SE向相关较好,此方向性与含量的空间分布走向一致。 展开更多
关键词 地统计学 空间分布 沉积物 重金属 长江 水系
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地质统计反演之随机地震反演方法——以苏丹M盆地P油田为例 被引量:62
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作者 李方明 计智锋 +2 位作者 赵国良 吴昌吉 李志明 《石油勘探与开发》 SCIE EI CAS CSCD 北大核心 2007年第4期451-455,共5页
随机地震反演是地质统计反演方法的重要组成部分,是地震反演与序贯模拟的结合。在随机地震反演过程中,首先统计随机变量的直方图分布,计算随机变量的变差函数,确定随机变量在不同方向上的变程;然后,针对每一种实现,在地震道位置根据计... 随机地震反演是地质统计反演方法的重要组成部分,是地震反演与序贯模拟的结合。在随机地震反演过程中,首先统计随机变量的直方图分布,计算随机变量的变差函数,确定随机变量在不同方向上的变程;然后,针对每一种实现,在地震道位置根据计算出来的反射系数人为合成地震道,比较合成道与原始地震道之间的误差,达到要求的精度后输出反演结果。以苏丹M盆地北部P油田为例,对波阻抗及测井数据进了直方图分析、变差图分析及相关性分析。用模拟退火方法对研究区全区的波阻抗体以及部分地区的密度体进行随机地震反演后发现,随机地震反演的波阻抗体与密度体反演剖面分辨率较高,甚至浅层薄砂体在反演结果上都有很好的反映,砂泥岩厚度的横向变化情况也刻画得非常好。结论表明,随机地震反演为油田开发阶段的地震反演提供了一种新的思路。 展开更多
关键词 地质统计反演 随机地震反演 变差函数 相关性分析
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