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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Développement d'essais pour évaluer la thixotropie et la robustesse des bétons autoplaçants

Naji, Siwar January 2009 (has links)
Bien que les connaissances sur les bétons autoplaçants (BAP) soient suffisantes pour permettre leur utilisation, certains paramètres mal exploités, tels que la thixotropie et la robustesse, restent à améliorer. Le premier objectif de ce mémoire est d'établir un protocole expérimental faisable sur chantier, pour mesurer la restructuration du béton, due au phénomène de la thixotropie. Durant la première partie de ce travail, cinq dispositifs expérimentaux ont été testés sur deux mortiers de bétons équivalents, et en second lieu, sur deux bétons autoplaçants. Les analyses sont basées sur la répétabilité et sur des corrélations entre les résultats de ces dispositifs avec ceux du rhéomètre. Les meilleurs essais empiriques, qui ont montré des erreurs relatives faibles et de très bonnes relations, tels que la palette portative, l'étalement au cylindre et le plan incliné, sont employés par la suite, pour étudier la robustesse des bétons autoplaçants. Dans la deuxième partie du mémoire, l'objectif consiste à étudier la robustesse de plusieurs bétons, vis-à-vis de la variation de l'humidité du sable et du dosage en superplastifiant, tout en analysant leurs propriétés pertinentes. En effet, nous avons adopté une méthode pour classer huit BAP, en matière de robustesse, confectionnés avec plusieurs combinaisons d'agents colloïdaux et de superplastifiants (PNS et PCP). Des analyses statistiques nous ont permis de sélectionner les meilleures propriétés étudiées, qui montrent une très bonne concordance de classement des bétons étudiés selon la robustesse. À partir de ces résultats, on a pu démontrer que l'essai de la palette portative est aussi adéquat pour déterminer la robustesse des BAP. En ce qui concerne l'effet des agents colloïdaux sur la robustesse, une classification a été faite, identifiant quatre catégories différentes. Les agents colloïdaux à base de polysaccharide, utilisés dans les bétons à base de polynaphtalène, qui permettent à ces derniers de développer une plus grande robustesse, appartiennent à la classe I. Un autre agent de viscosité de même famille appartient à la classe II, mais il confère au béton une robustesse moins importante. L'amidon modifié, qui offre aux BAP une tolérance moyenne aux changements de la quantité d'eau dans les mélanges se rapporte à la classe III. Enfin, le dérivé de cellulose, qui ne permet pas au BAP de développer une moindre robustesse, est catégorisé dans la classe IV. Une confirmation du même ordre de robustesse avec deux BAP différents a été prouvée durant la deuxième phase de cette partie, en modifiant le dosage de superplastifiant de «10 % par rapport au mélange de référence. La robustesse de ces deux bétons autoplaçants répond du même degré, tant à la variation de l'humidité de sable qu'à la variation de dosage de superplastifiant.
12

Home

Saunders-Spearman, Meagan 17 April 2013 (has links)
Fiction collection centered around an African-American family living in Hanover, Virginia.
13

On Rank-invariant Methods for Ordinal Data

Yang, Yishen January 2017 (has links)
Data from rating scale assessments have rank-invariant properties only, which means that the data represent an ordering, but lack of standardized magnitude, inter-categorical distances, and linearity. Even though the judgments often are coded by natural numbers they are not really metric. The aim of this thesis is to further develop the nonparametric rank-based Svensson methods for paired ordinal data that are based on the rank-invariant properties only. The thesis consists of five papers. In Paper I the asymptotic properties of the measure of systematic disagreement in paired ordinal data, the Relative Position (RP), and the difference in RP between groups were studied. Based on the findings of asymptotic normality, two tests for analyses of change within group and between groups were proposed. In Paper II the asymptotic properties of rank-based measures, e.g. the Svensson’s measures of systematic disagreement and of additional individual variability were discussed, and a numerical method for approximation was suggested. In Paper III the asymptotic properties of the measures for paired ordinal data, discussed in Paper II, were verified by simulations. Furthermore, the Spearman rank-order correlation coefficient (rs) and the Svensson’s augmented rank-order agreement coefficient (ra) were compared. By demonstrating how they differ and why they differ, it is emphasized that they measure different things. In Paper IV the proposed test in Paper I for comparing two groups of systematic changes in paired ordinal data was compared with other nonparametric tests for group changes, both regarding different approaches of categorising changes. The simulation reveals that the proposed test works better for small and unbalanced samples. Paper V demonstrates that rank invariant approaches can also be used in analysis of ordinal data from multi-item scales, which is an appealing and appropriate alternative to calculating sum scores.
14

Tests of Bivariate Stochastic Order

Liu, Yunfeng 28 September 2011 (has links)
The purpose of this thesis is to compare rank-based tests of bivariate stochastic order. Given two bivariate distributions $F$ and $G$, the general problem we are dealing with is to test $H_0: F=G$ against $H_1:F<G$, where $F$ and $G$ are independent continuous distributions on $\Re ^2$. (``$F<G$" means that $F(x)\leq G(x)~\forall x\in \Re^2$, and $\exists x\in \Re^2$ such that $F(x)< G(x)$.). In particular, we will analyze three analogues of the one-dimensional Mann-Whitney-Wilcoxon test in two dimensions. Two of the test statistics are new; we call them the Kendall and Spearman statistics. We will then show the asymptotic distributions and carry out empirical comparisons of the Kendall, Spearman and the third two-dimensional Mann-Whitney-Wilcoxon statistics.
15

Tests of Bivariate Stochastic Order

Liu, Yunfeng 28 September 2011 (has links)
The purpose of this thesis is to compare rank-based tests of bivariate stochastic order. Given two bivariate distributions $F$ and $G$, the general problem we are dealing with is to test $H_0: F=G$ against $H_1:F<G$, where $F$ and $G$ are independent continuous distributions on $\Re ^2$. (``$F<G$" means that $F(x)\leq G(x)~\forall x\in \Re^2$, and $\exists x\in \Re^2$ such that $F(x)< G(x)$.). In particular, we will analyze three analogues of the one-dimensional Mann-Whitney-Wilcoxon test in two dimensions. Two of the test statistics are new; we call them the Kendall and Spearman statistics. We will then show the asymptotic distributions and carry out empirical comparisons of the Kendall, Spearman and the third two-dimensional Mann-Whitney-Wilcoxon statistics.
16

Tests of Bivariate Stochastic Order

Liu, Yunfeng 28 September 2011 (has links)
The purpose of this thesis is to compare rank-based tests of bivariate stochastic order. Given two bivariate distributions $F$ and $G$, the general problem we are dealing with is to test $H_0: F=G$ against $H_1:F<G$, where $F$ and $G$ are independent continuous distributions on $\Re ^2$. (``$F<G$" means that $F(x)\leq G(x)~\forall x\in \Re^2$, and $\exists x\in \Re^2$ such that $F(x)< G(x)$.). In particular, we will analyze three analogues of the one-dimensional Mann-Whitney-Wilcoxon test in two dimensions. Two of the test statistics are new; we call them the Kendall and Spearman statistics. We will then show the asymptotic distributions and carry out empirical comparisons of the Kendall, Spearman and the third two-dimensional Mann-Whitney-Wilcoxon statistics.
17

Padr?es espaciais e temporais da fenologia de tr?s esp?cies arb?reas na regi?o do Alto Jequitinhonha

Magalh?es, Mariana Rodrigues 26 July 2013 (has links)
Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-07T11:11:35Z No. of bitstreams: 2 mariana_carolina_magalhaes.pdf: 2267644 bytes, checksum: d8a5e80ce31e3ecca7f32cb94d6d755b (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-07T11:12:01Z (GMT) No. of bitstreams: 2 mariana_carolina_magalhaes.pdf: 2267644 bytes, checksum: d8a5e80ce31e3ecca7f32cb94d6d755b (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-07T11:12:17Z (GMT) No. of bitstreams: 2 mariana_carolina_magalhaes.pdf: 2267644 bytes, checksum: d8a5e80ce31e3ecca7f32cb94d6d755b (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Made available in DSpace on 2015-01-07T11:12:17Z (GMT). No. of bitstreams: 2 mariana_carolina_magalhaes.pdf: 2267644 bytes, checksum: d8a5e80ce31e3ecca7f32cb94d6d755b (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Previous issue date: 2013 / Este trabalho teve como objetivo estudar o comportamento de tr?s esp?cies do Cerrado em tr?s ?reas distintas com base na rela??o com as condi??es meteorol?gicas e utilizar Redes Neurais Artificiais (RNAs) para prever a ocorr?ncia de eventos fenol?gicos. As esp?cies Caryocar brasiliense, Bowdichia virgilioides e Plathymenia reticulata foram selecionadas devido ao seu potencial em recuperar ?reas degradadas e multiprodutos. Os locais de estudo para a sazonalidade foram os munic?pios de Diamantina (DIA), S?o Gon?alo do Rio Preto (SGRP) e Itamarandiba (ITA) e para as RNAs foram DIA e ITA. Foram selecionados 12 indiv?duos de cada esp?cies em cada local. As visitas fenol?gicas foram realizadas quinzenalmente entre 2008 e 2011, sendo registradas as fenofases seguindo a escala de Fournier. Os dados meteorol?gicos foram fornecidos pelas Esta??es Climatol?gicas Principais de Diamantina e Itamarandiba. Para a rela??o entre as vari?veis meteorol?gicas e eventos fenol?gicos utilizou-se correla??es de Spearman (rs) e estat?stica circular para testar a ocorr?ncia de sazonalidade. As fenofases referentes ? folhagem e ?s fases reprodutivas foram quantificadas pelo do ?ndice de atividade. Nas tr?s ?reas os eventos relacionados ? folhagem e flora??o das tr?s esp?cies apresentaram sincronia e as fenofases referentes ? frutifica??o apresentaram sincronia para a Bowdichia virgilioides e Plathymenia reticulata, j? o Caryocar brasiliense apresentou sincronia entre DIA e SGRP. A maioria dos eventos apresentaram sazonalidade pelo menos para um dos per?odos estudados. As esp?cies apresentaram rela??o com as vari?veis meteorol?gicas, sendo que os intervalos parciais apresentaram tend?ncia diferente dos per?odos totais demostrando ? necessidade de uma s?rie hist?rica mais longa. Para a an?lise das RNAs, os dados referentes ?s fases reprodutivas foram processados para obten??o da estimativa atual e futura dos valores referentes ? porcentagem dos eventos fenol?gicos reprodutivos. As redes apresentaram-se como um grande apoio no estudo da fenologia, uma vez que com um banco de dados menor que tr?s anos os valores estimados foram muito pr?ximos dos observados principalmente quando utilizada uma fenofase por rede. A estimativa futura indicou a possibilidade de previs?o de eventos fenol?gicos possuindo apenas dados meteorol?gicos. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Ci?ncia Florestal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2013. / ABSTRACT This study aimed to understand the behavior of three species of the Cerrado in three distinct areas based on the relationship between meteorological conditions and use Artificial Neural Networks (ANN) to predict the occurrence of phenological events. The species Caryocar brasiliense, Bowdichia virgilioides and Plathymenia reticulata were selected because of their potential to recover degraded areas and multiproducts. The study locations for seasonality were the cities of Diamantina (DIA), S?o Gon?alo do Rio Preto (SGRP) and Itamarandiba (ITA) and for ANN were DIA and ITA. We selected 12 individuals of each species at each site. The phenological visits were every two weeks between 2008 and 2011 and the were registered phenophases following scale Fournier. Meteorological data were provided by Climatological Stations Main Diamantina and Itamarandiba. For the relationship between the meteorological variables and phenological events used Spearman correlations (rs) and circular statistics to test the occurrence of seasonality. The stages refer to the foliage and the reproductive phases were quantified using the activity index. In the three areas the events related foliage and flowering of three species presented synchrony and phenophases related to fruiting presented synchrony for Bowdichia virgilioides and Plathymenia reticulata, already the Caryocar brasiliense presented synchrony between the DIA and SGRP. Most events presented seasonality in the at least one of the study periods. The species presented relationship with meteorological variables studied, and the partial ranges presented different tendency of total periods demonstrating the need for a longer time series. For the analysis of the ANN, the data relating to reproductive phases of the studied species were processed to obtain estimates of current and future values ??for the percentage of reproductive phenological events. The networks presented as a lot of support in the study of phenology, because with a database of less than three years, the estimated values ??were very close to those observed especially when used one phenophase by network. The estimated future indicated the possibility of predicting phenological events having only meteorological data.
18

Avaliação de uma Classe de Coe cientes de Correlação sob Normalidade Bivariada

Xavier, Cleber Martins 19 February 2014 (has links)
Submitted by Etelvina Domingos (etelvina.domingos@ufpe.br) on 2015-03-12T19:15:11Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Cleber Martins Xavier.pdf: 17520287 bytes, checksum: d1c8c426b43447666fa634742f058bf5 (MD5) / Made available in DSpace on 2015-03-12T19:15:11Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Cleber Martins Xavier.pdf: 17520287 bytes, checksum: d1c8c426b43447666fa634742f058bf5 (MD5) Previous issue date: 2014-02-19 / CAPES / O coe ciente de correlação é uma medida que permite mensurar a dependência entre duas variáveis. Na literatura estatística existem diversos coe cientes de correlação, como por exemplo o de Pearson (Pearson, 1931 e Pearson, 1932), Kendall (Kendall, 1938) e Spearman (Spearman, 1904) que são usados sob diferentes condições dos dados. Nesta dissertação discutimos sobre o coe ciente de correlação generalizado proposto por Chinchilli et al. (2005), o qual é obtido através de estat ísticas U. Este coe ciente tem como casos especiais o coe ciente de correlação de Pearson e de Kendall. Neste trabalho foram desenvolvidos estudos de simulação a m de avaliar o comportamento do coe ciente de correlação generalizado em pequenas e grandes amostras e sob diferentes cenários que incluem amostras normais bivariadas, amostras bivariadas contaminadas e perturbadas. Por m, utilizando um banco de dados real de microarrays usamos o coe ciente de correlação generalizado na construção de uma rede de relevância.
19

Tests of Bivariate Stochastic Order

Liu, Yunfeng January 2011 (has links)
The purpose of this thesis is to compare rank-based tests of bivariate stochastic order. Given two bivariate distributions $F$ and $G$, the general problem we are dealing with is to test $H_0: F=G$ against $H_1:F<G$, where $F$ and $G$ are independent continuous distributions on $\Re ^2$. (``$F<G$" means that $F(x)\leq G(x)~\forall x\in \Re^2$, and $\exists x\in \Re^2$ such that $F(x)< G(x)$.). In particular, we will analyze three analogues of the one-dimensional Mann-Whitney-Wilcoxon test in two dimensions. Two of the test statistics are new; we call them the Kendall and Spearman statistics. We will then show the asymptotic distributions and carry out empirical comparisons of the Kendall, Spearman and the third two-dimensional Mann-Whitney-Wilcoxon statistics.
20

Nonparametric Tests for Umbrella Alternatives in Stratified Datasets

Larock, Josh 15 August 2023 (has links)
This thesis considers the problem of hypothesis testing for umbrella alternatives when there are two groups, or strata, of observations. The proposed methods extend a previously established general framework of hypothesis testing based on rankings to stratified datasets by first aligning the strata. The tests based on the Spearman and Kendall distances between ranking vectors lead to the traditional aligned-rank tests and new methods which account for “misalignment” under the alternative hypothesis. Asymptotic null distributions and simulation studies are given for the Spearman distance. Diagnostic tools for the misalignment issue are illustrated alongside the proposed tests on a dataset of IQ scores of coma patients. Extensions to three or more strata and ”adaptive” tests are provided as future research directions.

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