Sabiia Seb
PortuguêsEspañolEnglish
Embrapa
        Busca avançada

Botão Atualizar


Botão Atualizar

Ordenar por: RelevânciaAutorTítuloAnoImprime registros no formato resumido
Registros recuperados: 4
Primeira ... 1 ... Última
Imagem não selecionada

Imprime registro no formato completo
Advanced spectral analysis and cross correlation based on the empirical mode decomposition: application to the environmental time series ArchiMer
Ben Ismail, Dhouha Kbaier; Lazure, Pascal; Puillat, Ingrid.
Abstract—In marine sciences, time series are often nonlinear and nonstationary. Adequate and specific methods are needed to analyze such series. In this paper, an application of the Empirical Mode Decomposition method (EMD) associated to the Hilbert Spectral Analysis (HSA) is presented. Furthermore, EMD based Time Dependent Intrinsic Correlation (TDIC) analysis is applied to consider the correlation between two nonstationary time series. Four temperature time series obtained from automatic measurements in nearshore waters of the Réunion island are considered, recorded every ten minutes from July 2011 to January 2012. The application of the EMD on these series and the estimation of their power spectra using the HSA are illustrated. The authors identify...
Tipo: Text Palavras-chave: Augmented Dickey-Fuller tests; Cross correlation; Empirical mode decomposition (EMD); Hilbert spectral analysis (HSA); Hilbert-Huang transform (HHT); Stationarity; Time-dependent intrinsic correlation (TDIC); Time series; Wavelets.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00270/38077/36205.pdf
Imagem não selecionada

Imprime registro no formato completo
Application of Hilbert-Huang decomposition to temperature and currents data in the Réunion island ArchiMer
Kbaier-ben Ismail, Dhouha; Lazure, Pascal; Puillat Felix, Ingrid.
In marine sciences, time series are often nonlinear and nonstationary. Their analysis faces new challenges and thus requires the implementation of adequate and specific methods. We use the Hilbert-Huang Transform (HHT) for the spectral analysis of high frequency sampled time series in near shore waters of the Réunion island, located in the Indian Ocean 700 km east of Madagascar. We focus particularly on automatic measurements of sea level fluctuations, temperature records and current data sets at four different stations in the island. We look at the contribution of different Intrinsic Mode Functions (IMFs) obtained by the Empirical Mode Decomposition (EMD) and also compare the Hilbert spectra with the wavelet spectra. The inertial wave and several...
Tipo: Text Palavras-chave: Cross correlation; Empirical mode decomposition (EMD); Hilbert spectral analysis (HSA); Hilbert-Huang transform (HHT); Stationarity; Time-dependent intrinsic correlation (TDIC); Time series; Wavelets.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00383/49392/49822.pdf
Imagem não selecionada

Imprime registro no formato completo
Relaciones contemporáneas y rezagadas entre variables físicoquimicas y biológicas en la Ciénaga Grande de Santa Marta, Caribe colombiano OceanDocs
Zea, S.; Giraldo-H., R.; Mancera-P., J.E.; Martínez-C., J..
A partir de datos disponibles de cuatro estaciones de muestreo de la Ciénaga Grande de Santa Marta (Mar Caribe, Colombia), se exploraron las correlaciones cruzadas, contemporáneas y rezagadas en el tiempo, entre series quincenales de variables "biológicas" (clorofila a, producción primaria) y "fisicoquímicas" (salinidad, transparencia, nutrientes inorgánicos, nitrógeno y fósforo totales, feopigmentos, proteínas del seston). En contraste con análisis previos, el volver estacionarias las series (media y varianza constantes) eliminó variaciones de tendencia y magnitud asociadas con el clima, y enfatizó variaciones a una escala de semanas. Como resultado, cambios en la producción primaria no se relacionaron ni con los cambios contemporáneos en biomasa de...
Tipo: Journal Contribution Palavras-chave: Cross correlation; Primary production; Coastal lagoons; Primary production; Coastal lagoons; Http://aims.fao.org/aos/agrovoc/c_34329; Http://aims.fao.org/aos/agrovoc/c_1697.
Ano: 1998 URL: http://hdl.handle.net/1834/3304
Imagem não selecionada

Imprime registro no formato completo
Selecting statistical models to study the relationship between soybean yield and soil physical properties Rev. Bras. Ciênc. Solo
Oliveira,Marcio Paulo de; Tavares,Maria Hermínia Ferreira; Uribe-Opazo,Miguel Angel; Timm,Luis Carlos.
Statistical models allow the representation of data sets and the estimation and/or prediction of the behavior of a given variable through its interaction with the other variables involved in a phenomenon. Among other different statistical models, are the autoregressive state-space models (ARSS) and the linear regression models (LR), which allow the quantification of the relationships among soil-plant-atmosphere system variables. To compare the quality of the ARSS and LR models for the modeling of the relationships between soybean yield and soil physical properties, Akaike's Information Criterion, which provides a coefficient for the selection of the best model, was used in this study. The data sets were sampled in a Rhodic Acrudox soil, along a spatial...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Autocorrelation; Cross correlation; Linear regression; State-space model; Soil and plant properties.
Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832011000100009
Registros recuperados: 4
Primeira ... 1 ... Última
 

Empresa Brasileira de Pesquisa Agropecuária - Embrapa
Todos os direitos reservados, conforme Lei n° 9.610
Política de Privacidade
Área restrita

Embrapa
Parque Estação Biológica - PqEB s/n°
Brasília, DF - Brasil - CEP 70770-901
Fone: (61) 3448-4433 - Fax: (61) 3448-4890 / 3448-4891 SAC: https://www.embrapa.br/fale-conosco

Valid HTML 4.01 Transitional