Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 28 for “"variogram"”.
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Nonparametric modeling of dependencies for spatial interpolation
… dependency can be represented by an underlying covariogram, variogram, or generalized covariogram. Estimating this function in a nonparametric way is the theme of this thesis. If the function can be found accurately, then kriging is the optimal linear interpolation technique. A nev,· technique for …
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Variability Structure Estimation: The Role of Sample Support
… variability description. The experimental point variogram and the experimental histogram are the two most widely used statistical measures of variability structure. For a given spatial domain, it is often difficult to accurately estimate the point variogram due to sampling costs and limited …
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Variability structure estimation: The role of sample support
… variability description. The experimental point variogram and the experimental histogram are the two most widely used statistical measures of variability structure. For a given spatial domain, it is often difficult to accurately estimate the point variogram due to sampling costs and limited …
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Analysis of distribution maps from bird atlas data: dissimilarities between species, continuity within ranges and smoothing of distribution maps
… from The Atlas of Southern African Birds. The variogram, developed in geostatistics, estimates this spatial autocorrelation. The classical variogram estimator, however, is dependent on the scale of measurement and assumes that the data are intrinsically stationary. The bird atlas distribution …
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Multiscale decomposition of spatial lattice data for hotspot prediction
… surface. Herein, we extend the estimation of a variogram to spatial lattice data. In order to increase the number of data points from only the centroids of each spatial unit (representative points), multiple points are simulated in an appropriate way to represent the continuous nature of the …
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Topics in interpolation and smoothing of spatial data
… inappropriate in certain respects. The semi-variogram plays a central role in geostatistical work. In both of the applications considered here, the raw semi-variogram is 'contaminated' by error, but the error variance varies widely between data points, so that the spatial autocorrelation …
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Biga Yarımadası (Batı Anadolu)'ndaki değerli metallere ait dere sediman jeokimyası verilerinin modellenmesi
… Modelleme çalışmaları için elementlerin variogram fonksiyonları hesaplanmış, deneysel variogramları çizilmistir. İki boyutlu verilerde dört ana yönde hesaplama yapılmış ve bölgesel degiskenin izotrop oldugu varsayılmıstır. Daha sonra, bulunan deneysel variogramlara küresel model …
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Spatial modeling for periodic surfaces in manufacturing
… this paper, we propose a Bessel-based periodic variogram model, which enables kriging, a geostatistical interpolation method, to achieve accurate interpolation performance for common periodic surfaces. In addition, parameters of the proposed model provide valuable insights for the …
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Spatial accumulation patterns of snow water equivalent in the southern Rocky Mountains
… at a domain of 757 km. This study used variogram analysis for SWE data from 90 long-term SNOTEL stations to determine if a physical distance exists at which snow accumulation patterns across the southern Rocky Mountains vary abruptly. The concurrent accumulation period from SNOTEL …
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Geomechanical Reservoir Model Calibration and Uncertainty Assessment from Microseismic Data
… fractures. We also investigate the effect of variogram model uncertainty in the EnKF performance and propose a modified EnKF algorithm to handle the uncertainty in variogram parameters. We also develop a computationally efficient data assimilation procedure by employing a pseudo forecast …
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Rainfall redistribution and change of water quality in tropical forest canopies : patterns and persistence
… particular those of large events, require robust variogram estimation if one wants to avoid outlier removal. This finding is important because all geostatistical throughfall studies that have been published so far analyzed their data using the classical, non-robust variogram estimator.
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Spatial and temporal variability of the soil saturated hydraulic conductivity in gradients of disturbance
… data, including exploratory data analysis and variogram estimation techniques; I subsequently evaluated the results in terms of spatial prediction uncertainty. Concerning the exploratory data analysis, my main results were: 1) Gaussian uni- and bivariate distributions of the log-transformed …
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Surface forcing of the North Atlantic: accuracy and variability
… in<br/>terms of random errors using a semi-variogram analysis and a range of variogram<br/>models. The data quality and sampling are then taken into account using optimal<br/>interpolation (OI) to grid the observations, producing daily mean fields and uncertainty<br/>estimates. These are …
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Spatial Patterns in a 40-year-old Slash Pine (Pinus elliottii Engelm.) Forest in the Coastal Plain of South Carolina
… tests, canonical correlation analysis, variogram modeling and kriging. The average range of spatial autocorrelation for the forest floor variables was >45 m, while that for soil variables was 12 m. Woody stem basal area exhibited spatial autocorrelation at ranges of less than 12 m, and …
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The effect of locational uncertainty in geostatistics
… on the spatial lag, the covariance function, the variogram, and optimal spatial prediction (aka, kriging). We show that the basic methodology of kriging adjusted for locational error is the same as kriging without locational error;We also develop a hierarchical Bayesian model to incorporate …
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Implementation and comparative analysis of supervised machine learning methods for domain modeling and grade estimation techniques
… always hold true, and common practices, such as variogram interpretations, and data filtering, can introduce errors early in the modeling process. Supervised Machine learning (ML) offers a promising alternative, capable of handling complex data sets for domain analysis and grade estimation. This …
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Spatial variability of hydraulic properties as affected by physical properties of selected soil types in South Africa
… to generate spatial variability maps and semi variograms. The University of Venda Experimental farm had lesser spatial variability with coefficient of variation ranging from 9.6 to 33.4%. The spatial variability of soil was very low confirmed by contour maps depicting slightly homogeneity. …
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Evaluating Spatial Variability of Precipitation in Kentucky with Exploratory Data Analysis
… were classified based on percentiles of the variogram cloud. The data were condensed into distance bins for analysis and used for calculation of the indices. A Short Range Index (SRI) and Long Range Index (LRI) were calculated for each month. The indices were then analyzed through the use of …
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A geo-cellular model of a multiphase hydrocarbon field incorporating fault-seal analysis : Bredasdorp Basin, South Africa
… reservoir parameters were modelled using a variogram except in the case of water saturation, which was modelled using a J function equation. The volumetrics were assigned per fault block. Using a recovery factor of 75% for gas and 11% for oil, the calculated total recoverable hydrocarbons …
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