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	Provedor de dados Bragantia (2) Autor Carvalho,José Ruy Porto de (2) González,Antonio Paz (2) Vieira,Sidney Rosa (2) Ceddia,Marcos Bacis (1) Palavra-chave Scale of variation (2) Semivariograms (2) Stationarity (2) Topography (2) Tipo do documento Info:eu-repo/semantics/article (2) Ano 2010 (2) País Brazil (2) Idioma Inglês (2)		Ordenar por:  Relevância Autor Título Ano Registros recuperados: 2 Primeira ... 1 ... Última Jack knifing for semivariogram validation Bragantia Vieira,Sidney Rosa; Carvalho,José Ruy Porto de; González,Antonio Paz. The semivariogram function fitting is the most important aspect of geostatistics and because of this the model chosen must be validated. Jack knifing may be one the most efficient ways for this validation purpose. The objective of this study was to show the use of the jack knifing technique to validate geostatistical hypothesis and semivariogram models. For that purpose, topographical heights data obtained from six distinct field scales and sampling densities were analyzed. Because the topographical data showed very strong trend for all fields as it was verified by the absence of a sill in the experimental semivariograms, the trend was removed with a trend surface fitted by minimum square deviation. Semivariogram models were fitted with different... Tipo: Info:eu-repo/semantics/article Palavras-chave: Semivariograms; Stationarity; Topography; Scale of variation. Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052010000500011 Detrending non stationary data for geostatistical applications Bragantia Vieira,Sidney Rosa; Carvalho,José Ruy Porto de; Ceddia,Marcos Bacis; González,Antonio Paz. The use of geostatistics requires at least that the intrinsic hypothesis be satisfied. The presence of a trend in the data invalidates this hypothesis. One of the ways of solving this problem is by subtracting a function fitted to the original data and working with the residuals. This technique also represents a change to a smaller scale of the variability and surface roughness. This paper describes the detrending technique of subtracting a trend surface fitted by the least squares method and discusses the results using topographical data as examples. The objective is to show how the detrending technique works for different scales and degrees of trend and how to interpret the results. It is shown that the simplest the surfaces fitted that does the work of... Tipo: Info:eu-repo/semantics/article Palavras-chave: Semivariograms; Stationarity; Topography; Scale of variation. Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052010000500002 Registros recuperados: 2 Primeira ... 1 ... Última

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