Covariance Matrix
Mostrando 1-12 de 68 artigos, teses e dissertações.
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1. Assessment of Covariance Selection Methods in High-Dimensional Gaussian Graphical Models
ABSTRACT The covariance selection in Gaussian graphical models consists in selecting, based on a sample of a multivariate normal vector, all those pairs of variables that are conditionally dependent given the remaining variables. This problem is equivalent to estimate the graph identifying the nonzero elements on the off-diagonal entries of the precision mat
Trends in Computational and Applied Mathematics. Publicado em: 2022
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2. MULTILEVEL NONLINEAR MIXED-EFFECTS MODEL AND MACHINE LEARNING FOR PREDICTING THE VOLUME OF Eucalyptus SPP. TREES
ABSTRACT Volumetric equations is one of the main tools for quantifying forest stand production, and is the basis for sustainable management of forest plantations. This study aimed to assess the quality of the volumetric estimation of Eucalyptus spp. trees using a mixed-effects model, artificial neural network (ANN) and support-vector machine (SVM). The datab
CERNE. Publicado em: 2020-03
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3. Considering the impact of observation error correlation in ensemble square-root Kalman filter
Abstract Data assimilation has been developed into an effective technology that can utilize a large number of multi-source unconventional data. It cannot only provide the initial field for the ocean numerical prediction model, but also construct the ocean reanalysis datasets and provide the design basis for the ocean observation plan. In data assimilation, t
Braz. j. oceanogr.. Publicado em: 02/12/2019
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4. SITE INDEX FOR PROSOPIS ALBA PLANTATIONS IN THE SEMI-ARID CHACO THROUGH MIXED MODELS
ABSTRACT The classification of sites through curves of Site Index allows to predict the yield of the planted forests at a certain age of the stand and to plan cultural treatments. The goal of this research was to compare linear and non-linear models of fixed effects vs. mixed non-linear models to estimate the site index in plantations of Prosopis alba var Gr
CERNE. Publicado em: 09/09/2019
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5. Principal Component Analysis and Factor Analysis: differences and similarities in Nutritional Epidemiology application
RESUMO: Introdução: Métodos estatísticos de análise multivariada, tais como Análise de Componentes Principais e Análise Fatorial, têm sido cada vez mais utilizados nos estudos em Epidemiologia Nutricional, no entanto equívocos quanto à escolha e aplicação dos métodos são observados. Objetivos: Os objetivos deste estudo são comparar e apres
Rev. bras. epidemiol.. Publicado em: 29/07/2019
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6. Repeatability of morpho-agronomic characters of Theobroma grandiflorum fruits
Resumo Este trabalho teve como objetivos estimar coeficientes de repetibilidade, determinar o número mínimo de frutos necessários para seleção de genótipos e estimar coeficientes de correlação fenotípica entre caracteres morfoagronômicos de frutos de cupuaçuzeiros. Foram avaliados 22 genótipos de um sistema agroflorestal implantado no município
Rev. Bras. Frutic.. Publicado em: 11/04/2019
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7. Longitudinal data assessment of global stability index in kale leaves
ABSTRACT Kale plants are usually sold “in natura” in street markets and malls. Kale leaves can have their appearance compromised by dehydration and discoloration due to increased post-harvest time exposure. We aimed to analyze the Global Stability Index (GSI) in kale accessions by means of repeated measurement analysis and curve grouping as a complementa
Sci. agric. (Piracicaba, Braz.). Publicado em: 2016-02
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8. Four-way data analysis within the linear mixed modelling framework
Cultivars have to be evaluated under different crop management systems across agro-ecosystems and years using multi-environment trials (MET) before releasing them to the market. Frequently, data collected in METs are arranged according to cultivar (G), management (M), location, (L) and year (Y) combinations in a four-way G x M x L x Y data table that is high
Sci. agric. (Piracicaba, Braz.). Publicado em: 2015-10
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9. ON HYPOTHESIS TESTS FOR COVARIANCE MATRICES UNDER MULTIVARIATE NORMALITY
In this paper we proposed a new statistical test for testing the covariance matrix in one population under multivariate normal assumption. In general, the proposed and the likelihood-ratio tests resulted in larger values of estimated powers than VMAX for bivariate and trivariate cases. VMAX was not sensitive to general changes in the covariance (correlation)
Pesqui. Oper.. Publicado em: 2015-04
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10. State estimation of chemical engineering systems tending to multiple solutions
A well-evaluated state covariance matrix avoids error propagation due to divergence issues and, thereby, it is crucial for a successful state estimator design. In this paper we investigate the performance of the state covariance matrices used in three unconstrained Extended Kalman Filter (EKF) formulations and one constrained EKF formulation (CEKF). As bench
Braz. J. Chem. Eng.. Publicado em: 2014-09
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11. Genetic parameters and trends of morphometric traits of GIFT tilapia under selection for weight gain
The main factor considered in breeding programs for fish is growth, which can be assessed in terms of a gain in either weight or body measurements. This study was undertaken to evaluate the morphometric traits of GIFT strain tilapia (Oreochromis sp.) selected for weight gain. The data set used contained information on 6,650 animals. The genetic values of 8,5
Sci. agric. (Piracicaba, Braz.). Publicado em: 2014-08
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12. Repeatability of agronomic characters in Brachiaria brizantha cultivars
This experiment was carried out with the objectives of determining repeatability coefficients, the number of harvests necessary to increase accuracy and the genotypic stability of yield characteristics in Brachiaria brizantha cultivars in the northeast region of Brazil in the period from July 2009 to March 2011. The experimental design used was completely ra
R. Bras. Zootec.. Publicado em: 2013-01