نتایج جستجو برای: and exponential variograms

تعداد نتایج: 16835200  

ژورنال: علوم آب و خاک 2004
جهانگرد محمدی, , فایز رئیسی گهرویی, ,

Knowledge of the spatial dependency of soil properties, sensitive to grazing systems, is important from an ecosystem protection point of view. In the current study, geostatistical methods and fractal concepts have been used in order to characterize the impact of long-term grazing exclusion on the spatial variability of some soil chemical parameters including organic matter, total nitrogen, avai...

2005
Luben D. Dimov Jim L. Chambers Brian Roy Lockhart

Sustainable forest management and conservation require understanding of underlying basic structural and competitive relationships. To gain insight into these relationships, we analyzed spatial continuity of tree basal area (BA) and crown projection area (CPA) on twelve 0.64-ha plots in four mixed bottomland hardwood stands in Louisiana, Arkansas, and Mississippi. Variogram range indicated that ...

Journal: :Remote Sensing 2014
Muhammad Kamal Stuart R. Phinn Kasper Johansen

Understanding the relationship between the size of mangrove structural features and the optimum image pixel size is essential to support effective mapping activities in mangrove environments. This study developed a method to estimate the optimum image pixel size for accurately mapping mangrove features (canopy types and features (gaps, tree crown), community, and cover types) and tested the app...

2003
M. J. Pyrcz

The spatial continuity of the variables we model in geostatistics is dependent on the modelling and reproduction of the variogram. The variogram defines the relationship between variability (or geologic distance) and the lag distance (or Euclidian distance). As the magnitude of the lag separation vector increases, we typically expect the variogram to also increase. This is generally observed. T...

2014
P. Chernyavskiy C. M. Hudac D. L. Molfese D. B. Marx

Electroencephalography (EEG) is an important tool in neuroscience used to study the electrical brain responses following traumatic brain injuries (TBI), with the goal of clinical diagnosis and assessment. It is widely recognized that EEG produces inherently spatio-temporal data; however, the use of analytical methods that explicitly account for auto-correlation in both space and time have been ...

2017
Jay M. Ver Hoef Noel A. Cressie Ronald P. Barry

Models for spatial autocorrelation and cross-correlation depend on the distance and direction separating two locations, and are constrained so that for all possible sets of locations, the covariance matrices implied from the models remain nonnegative-definite. Based on spatial correlation, optimal linear predictors can be constructed that yield complete maps of spatial fields from incomplete an...

2002
R. M. Lark A. Papritz

It is not simple to model cross and auto-variograms to describe the covariation of two or more soil properties, since the models that are fitted must meet certain constraints. These constraints are most readily met by fitting a linear model of coregionalization (LMCR). This presents practical problems. Not all combinations of authorized variogram functions constitute a LMCR. This paper presents...

1994
Michel GRZEBYK

Comparing different scales in space or time the correlation between regionalized quantities can change substantially. Coregionalization models incorporate a description of the variation and covariation of a set of variables at different characteristic scales either in space or in time. Such models can be used as a device to explore the structure of multivariate spatial or temporal data in the f...

Journal: :caspian journal of environmental sciences 2014
f. karandish a. shahnazari

the present study was carried out to evaluate three interpolation methods including weighted moving average (wma) with the power of 2 and 3, kriging and cokriging methods. data of 23 wells in mazandaran province were collected in fall and spring 2006. seven parameters including electrical conductivity (ec), ph, total dissolved solids (tds), sodium adsorption ratio (sar), total hardness (th), ch...

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