• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • 2
  • 1
  • 1
  • Tagged with
  • 9
  • 9
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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.
1

The dielectric properties of solid biofuels

Paz, Ana Marta January 2010 (has links)
The use of bioenergy has been increasing due to efforts in fossil fuels replacement. Modern bioenergy technologies aim for high efficiency and low pollution levels, which increases the need for methods for the on-line characterization of biofuels. Dielectric methods have been identified as useful for the sensing of solid biofuels because they allow for rapid, nonhazardous, nondestructive, and bulk determination of material properties. The dielectric properties describe the interaction between the material and the electromagnetic waves. Dielectric properties are intrinsic of the materials and can therefore be used for the development of prediction models that can be applied regardless of the measurement technique. The study of the dielectric properties is also important as it improves the understanding of the dielectric behavior of the materials. This thesis focuses on the dielectric properties of solid biofuels and their use in the characterization of these materials. The work presented includes the development of new methods permitting the determination of the dielectric properties of solid biofuels with large particle size (waveguide method), broadband measurement of the dielectric properties (coaxial-line probe), and the use of a previously developed method for the accurate determination of the dielectric properties (free-space method). The results includes the dielectric properties of solid biofuels and their dependence on parameters such as frequency, moisture, density, and temperature. This thesis also presents semi-theoretical models for the determination of moisture content, which obtained a RMSEP of 4% for moisture contents between 34 and 67%, and an empirical model that resulted in a RMSEC of 0.3% for moisture contents between 4 and 13%. Finally, this thesis includes measurements of the influence of salt content on the dielectric properties and a discussion of its use for estimation of the ash content of solid biofuels. 
2

Estimação do teor de cinzas da camada I do carvão do leão através da reflectância utilizando a teoria Kubelka-Munk

Jesus, Leandro Gustavo Mendes de January 2014 (has links)
O principal parâmetro de avaliação da qualidade de carvões para uso na geração de energia termoelétrica é o percentual de cinzas. Em uma planta de beneficiamento, saber o percentual de cinzas da alimentação, concentrado e rejeito é de suma importância para os ajustes nos equipamentos de concentração. No caso do carvão da camada I1 do depósito mineral do Leão a janela de tempo entre o ponto mais adequado para amostragem e o fim da campanha de beneficiamento não propicia que se conheça o teor de cinzas da alimentação do processo de beneficiamento. Em virtude disso, este trabalho tem como objetivo de fornecer uma estimativa confiável do teor de cinzas da alimentação para propiciar a aplicação na planta de beneficiamento. Para esse intento utilizou-se a teoria de Kubelka-Munk que por meio de sua expressão matemática transforma a reflectância em uma grandeza aditiva que propicia a estimativa das porcentagens de matéria orgânica e mineral contida no carvão devido a diferença de reflectância entre esses materiais. Como resultado final foram gerados diversos modelos com intuito de verificar qual deles se adaptava melhor aos dados. Por fim, foi possível concluir que há possibilidade de estimar o teor de cinzas de carvão por meio da reflectância e com confiabilidade de 96,78% que toda a leitura agrega um erro máximo de ± 5% para o melhor modelo. / The main parameter in quality evaluation of coals employed in power generation is the ash content. In a beneficiation plant, knowing the ash content of the feed, concentrate an tailings is mandatory to set up the concentration equipment. In the case of the I1 coal seam of Leão’s deposit the time window between sampling routine and beneficiation routine does not allow to know the feed ash content before the beneficiation process. By this reason, this work aims to provide a reliable estimative of the feed ash content to propitiate its application in the beneficiation plant. For this purpose it was used Kubelka-Munk’s theory that, by using a mathematic expression, transforms reflectance into a additive quantity which allows to estimate mineral and organic matter present in coal by the difference of reflectance between these materials. As result, it was generated several models in order to analyze which one is better suited to the data. Finally, as a conclusion, it is possible to infer the ash content of coal by reflectance with confidence of 96,78% that all measure brings up a maximum error of ± 5% for the best model.
3

Estimação do teor de cinzas da camada I do carvão do leão através da reflectância utilizando a teoria Kubelka-Munk

Jesus, Leandro Gustavo Mendes de January 2014 (has links)
O principal parâmetro de avaliação da qualidade de carvões para uso na geração de energia termoelétrica é o percentual de cinzas. Em uma planta de beneficiamento, saber o percentual de cinzas da alimentação, concentrado e rejeito é de suma importância para os ajustes nos equipamentos de concentração. No caso do carvão da camada I1 do depósito mineral do Leão a janela de tempo entre o ponto mais adequado para amostragem e o fim da campanha de beneficiamento não propicia que se conheça o teor de cinzas da alimentação do processo de beneficiamento. Em virtude disso, este trabalho tem como objetivo de fornecer uma estimativa confiável do teor de cinzas da alimentação para propiciar a aplicação na planta de beneficiamento. Para esse intento utilizou-se a teoria de Kubelka-Munk que por meio de sua expressão matemática transforma a reflectância em uma grandeza aditiva que propicia a estimativa das porcentagens de matéria orgânica e mineral contida no carvão devido a diferença de reflectância entre esses materiais. Como resultado final foram gerados diversos modelos com intuito de verificar qual deles se adaptava melhor aos dados. Por fim, foi possível concluir que há possibilidade de estimar o teor de cinzas de carvão por meio da reflectância e com confiabilidade de 96,78% que toda a leitura agrega um erro máximo de ± 5% para o melhor modelo. / The main parameter in quality evaluation of coals employed in power generation is the ash content. In a beneficiation plant, knowing the ash content of the feed, concentrate an tailings is mandatory to set up the concentration equipment. In the case of the I1 coal seam of Leão’s deposit the time window between sampling routine and beneficiation routine does not allow to know the feed ash content before the beneficiation process. By this reason, this work aims to provide a reliable estimative of the feed ash content to propitiate its application in the beneficiation plant. For this purpose it was used Kubelka-Munk’s theory that, by using a mathematic expression, transforms reflectance into a additive quantity which allows to estimate mineral and organic matter present in coal by the difference of reflectance between these materials. As result, it was generated several models in order to analyze which one is better suited to the data. Finally, as a conclusion, it is possible to infer the ash content of coal by reflectance with confidence of 96,78% that all measure brings up a maximum error of ± 5% for the best model.
4

Estimação do teor de cinzas da camada I do carvão do leão através da reflectância utilizando a teoria Kubelka-Munk

Jesus, Leandro Gustavo Mendes de January 2014 (has links)
O principal parâmetro de avaliação da qualidade de carvões para uso na geração de energia termoelétrica é o percentual de cinzas. Em uma planta de beneficiamento, saber o percentual de cinzas da alimentação, concentrado e rejeito é de suma importância para os ajustes nos equipamentos de concentração. No caso do carvão da camada I1 do depósito mineral do Leão a janela de tempo entre o ponto mais adequado para amostragem e o fim da campanha de beneficiamento não propicia que se conheça o teor de cinzas da alimentação do processo de beneficiamento. Em virtude disso, este trabalho tem como objetivo de fornecer uma estimativa confiável do teor de cinzas da alimentação para propiciar a aplicação na planta de beneficiamento. Para esse intento utilizou-se a teoria de Kubelka-Munk que por meio de sua expressão matemática transforma a reflectância em uma grandeza aditiva que propicia a estimativa das porcentagens de matéria orgânica e mineral contida no carvão devido a diferença de reflectância entre esses materiais. Como resultado final foram gerados diversos modelos com intuito de verificar qual deles se adaptava melhor aos dados. Por fim, foi possível concluir que há possibilidade de estimar o teor de cinzas de carvão por meio da reflectância e com confiabilidade de 96,78% que toda a leitura agrega um erro máximo de ± 5% para o melhor modelo. / The main parameter in quality evaluation of coals employed in power generation is the ash content. In a beneficiation plant, knowing the ash content of the feed, concentrate an tailings is mandatory to set up the concentration equipment. In the case of the I1 coal seam of Leão’s deposit the time window between sampling routine and beneficiation routine does not allow to know the feed ash content before the beneficiation process. By this reason, this work aims to provide a reliable estimative of the feed ash content to propitiate its application in the beneficiation plant. For this purpose it was used Kubelka-Munk’s theory that, by using a mathematic expression, transforms reflectance into a additive quantity which allows to estimate mineral and organic matter present in coal by the difference of reflectance between these materials. As result, it was generated several models in order to analyze which one is better suited to the data. Finally, as a conclusion, it is possible to infer the ash content of coal by reflectance with confidence of 96,78% that all measure brings up a maximum error of ± 5% for the best model.
5

Determinação de conteúdo para geração de língua natural baseada em personalidade / Content planning for natural language generation based on personality

Ramos, Ricelli Moreira Silva 25 June 2018 (has links)
O presente trabalho aborda a determinação de conteúdo na fase de planejamento do documento no pipeline de Geração de Língua Natural (GLN) usando fatores de personalidade do modelo dos Cinco Grandes Fatores (CGF). O principal objetivo deste trabalho é gerar modelos computacionais de determinação de conteúdo baseados nos fatores de personalidade CGF. O trabalho aplicará técnicas já existentes de GLN para determinação de conteúdo, levando em conta os fatores de personalidade mapeados pelo modelo CGF. São utilizados os conceitos descritos por substantivos e os conceitos descritos por adjetivos relacionados aos substantivos na tarefa de descrição de cenas para a determinação de conteúdo. As principais contribuições desse trabalho são uma investigação de se e como a determinação de conteúdo de descrições textuais é influenciada pela personalidade do autor, além de entregar um modelo de determinação de conteúdo baseado em personalidade para os conceitos em que o trabalho foi aplicado, entre outras entregas. É apresentado o embasamento teórico com os conceitos fundamentais de GLN, e mais especificamente de determinação de conteúdo, foco dessa pesquisa. Além disso, são apresentados os modelos de personalidade humana, com destaque ao modelo CGF e inventários CGF, utilizados para a coleta de dados e execução dessa proposta. São apresentados também os principais trabalhos relacionados à GLN e modelo CGF, mesmo que não tratem especificamente da influência dos CGF na determinação de conteúdo. Um experimento para coleta do córpus utilizado na pesquisa é descrito, e também os modelos para determinação de conteúdo no âmbito de conceitos representando entidades visuais e seus predicados, assim como a avaliação desses modelos. Por fim, são apresentadas as conclusões obtidas com os modelos desenvolvidos e experimentos realizados / The present research approaches the content determination in the document planning phase of the Natural Language Generation (NLG) pipeline using personality factors of the Big Five Factor (BFF) model. The main objective of this research is to generate computational models of content determination based on the BFF personality factors. This research will apply existing NLG models to the content determination, taking into account the personality factors mapped by the BFF model. The concepts described by nouns and the concepts described by adjectives related to nouns in the task of describing scenes for content determination are used. The main contributions of this research are an investigation of if and how the content determination of textual descriptions is influenced by the personality of the author, in addition to providing a personality-based content determination model for the concepts in which the research was applied, among others deliveries. This document presents the theoretical basis and the fundamental NLG concepts, and more specifically the concept of content determination, which is the focus of this research. In addition, human personality models are presented, with emphasis on the BFF model and BFF inventories, used both for data collection and development of this proposal. The main studies related to NLG and the BFF model, even if they do not specifically address the influence of BFF in content determination, are also presented. An experiment for collecting the corpus used in the research is described, also the models to determine content in the scope of concepts representing visual entities and their predicates, as well as an evaluation of these models. Finally, the conclusions obtained with the developed models and experiments are presented
6

Determinação de conteúdo para geração de língua natural baseada em personalidade / Content planning for natural language generation based on personality

Ricelli Moreira Silva Ramos 25 June 2018 (has links)
O presente trabalho aborda a determinação de conteúdo na fase de planejamento do documento no pipeline de Geração de Língua Natural (GLN) usando fatores de personalidade do modelo dos Cinco Grandes Fatores (CGF). O principal objetivo deste trabalho é gerar modelos computacionais de determinação de conteúdo baseados nos fatores de personalidade CGF. O trabalho aplicará técnicas já existentes de GLN para determinação de conteúdo, levando em conta os fatores de personalidade mapeados pelo modelo CGF. São utilizados os conceitos descritos por substantivos e os conceitos descritos por adjetivos relacionados aos substantivos na tarefa de descrição de cenas para a determinação de conteúdo. As principais contribuições desse trabalho são uma investigação de se e como a determinação de conteúdo de descrições textuais é influenciada pela personalidade do autor, além de entregar um modelo de determinação de conteúdo baseado em personalidade para os conceitos em que o trabalho foi aplicado, entre outras entregas. É apresentado o embasamento teórico com os conceitos fundamentais de GLN, e mais especificamente de determinação de conteúdo, foco dessa pesquisa. Além disso, são apresentados os modelos de personalidade humana, com destaque ao modelo CGF e inventários CGF, utilizados para a coleta de dados e execução dessa proposta. São apresentados também os principais trabalhos relacionados à GLN e modelo CGF, mesmo que não tratem especificamente da influência dos CGF na determinação de conteúdo. Um experimento para coleta do córpus utilizado na pesquisa é descrito, e também os modelos para determinação de conteúdo no âmbito de conceitos representando entidades visuais e seus predicados, assim como a avaliação desses modelos. Por fim, são apresentadas as conclusões obtidas com os modelos desenvolvidos e experimentos realizados / The present research approaches the content determination in the document planning phase of the Natural Language Generation (NLG) pipeline using personality factors of the Big Five Factor (BFF) model. The main objective of this research is to generate computational models of content determination based on the BFF personality factors. This research will apply existing NLG models to the content determination, taking into account the personality factors mapped by the BFF model. The concepts described by nouns and the concepts described by adjectives related to nouns in the task of describing scenes for content determination are used. The main contributions of this research are an investigation of if and how the content determination of textual descriptions is influenced by the personality of the author, in addition to providing a personality-based content determination model for the concepts in which the research was applied, among others deliveries. This document presents the theoretical basis and the fundamental NLG concepts, and more specifically the concept of content determination, which is the focus of this research. In addition, human personality models are presented, with emphasis on the BFF model and BFF inventories, used both for data collection and development of this proposal. The main studies related to NLG and the BFF model, even if they do not specifically address the influence of BFF in content determination, are also presented. An experiment for collecting the corpus used in the research is described, also the models to determine content in the scope of concepts representing visual entities and their predicates, as well as an evaluation of these models. Finally, the conclusions obtained with the developed models and experiments are presented
7

Vliv oxidu barnatého na tvorbu a vlastnosti portlandského slínku / The influence of barium oxide on the formation and properties of portland clinker

Zezulová, Anežka January 2014 (has links)
Portland clinker is thanks to its large-scale production a continuously studied topic. Clinker, or Portland cement, is used for construction purposes, or for insulation and special applications. One of these special applications could be shielding of different types of radiation by making use of the content of barium ions. The present master’s thesis examines the influence of barium oxide on the formation and properties of Portland clinker, which could be, by incorporation of barium ions into the system, used as a binder for buildings resistant to various types of radiation. Barium sulfate and barium carbonate were added to the raw meal in order to prepare clinkers with different content of barium oxide. The effect of barium on the formation of clinker phases was studied (by XRD – Rietveld analysis and by the microscopic point integration), as well as the effects on the variations of temperature of the phase formation (TG-DTA) and the rate of alite formation under isothermal conditions. Furthermore, the ability of barium to become a part of clinker minerals was studied by SEM with EDS, and the solubility of barium phases by ICP-OES. The hydration of clinker minerals containing barium was studied by isothermal calorimetry.
8

ETUDE DE LA REACTIVITE DES LAITIERS DE HAUT-FOURNEAU DANS LES CIMENTS DE TYPE CEM III STUDY OF THE BLAST-FURNACE SLAG REACTIVITY IN CEM III/B CEMENTS

Vanhamme, Géraldine G B B 23 February 2011 (has links)
En Europe, suite à la fermeture de nombreux sites sidérurgiques, une utilisation croissante de laitiers de haut-fourneau d’origine et d’âge variés voit le jour depuis plusieurs années. Cette évolution conduit à une diversification de la composition chimique et minéralogique des laitiers. Connaître l’influence de ces caractéristiques sur la réactivité des laitiers utilisés en substitution du clinker dans les ciments de haut-fourneau (CEM III) devient, dès lors, primordial pour assurer les performances de tels ciments. Dans ce contexte, le présent travail a pour but d’investiguer l’influence de la composition chimique et de l’âge des laitiers sur leur réactivité tant par des essais physico-mécaniques que par une caractérisation physico-chimique et minéralogique de CEM III/B à différentes échéances d’hydratation. L’effet néfaste du vieillissement des laitiers est clairement mis en exergue et son impact diffère selon la composition chimique de départ du laitier. Les ions aluminium engendrent une accélération de l’hydratation et une amélioration des résistances physico-mécaniques à jeune âge mais, à long terme, ils conduisent à une perte de ces dernières. Concernant l’influence des ions titane dans les laitiers, la tendance générale observée est une diminution des performances physico-mécaniques. Sur base de ces résultats, une évaluation de la représentativité de moyens accélérés d’estimation de la réactivité des laitiers est effectuée. Il est mis en évidence que seules les mesures de résistances physico-mécaniques classiques permettent d’évaluer correctement la réactivité des différents laitiers. Une évaluation de la détermination de la teneur en constituants de CEM III/B par la méthode Rietveld est menée par comparaison avec la méthode de dissolution sélective de la norme EN 196-4 et le dosage des constituants par pesée. Moyennant une utilisation adaptée de cette méthode, les résultats obtenus à l’aide de celle-ci sont très encourageants. In Europe, following the closure of many steel plants, an increased use of blast furnace slag (BFS) of various age and origin was born for several years. This evolution leads to a diversification of the chemical and mineralogical composition of the BFS. Knowing the influence of these characteristics on the reactivity of slag used in substitution of clinker in blast-furnace cement (CEM III) becomes, therefore, crucial to ensure the performance of such cements. In this context, this work aims to investigate the influence of chemical composition and age of BFS on their reactivity by both physico-mechanical and physico-chemical and mineralogical characterization of CEM III/B at different times of hydration. The adverse effect of ageing of BFS is clearly highlighted and its impact varies depending on the chemical composition of the BFS. Aluminum ions generate an acceleration of the hydration and improve mechanical strength at early age, but at long term, they lead to a loss of the strength. Regarding the influence of titanium ions in the BFS, the general trend is a decrease of the physical and mechanical performance. Based on these results, an assessment of the representativeness of accelerated means of estimating, the BFS reactivity is done. It is emphasized that only measures of physical and conventional mechanical strength can accurately assess the reactivity of different BFS. An evaluation of the determination of the amount of CEM III/B components by the Rietveld method is based upon comparison with the selective dissolution method from the EN 196-4 norm and components determination by weight. Through appropriate use of this method, the results obtained are very encouraging.
9

Etude de la réactivité des alitiers du haut-fourneau dans les ciments de type CEM III / Study of the blast-furnace slag reactivity in CEM III/B cements

Vanhamme, Géraldine 23 February 2011 (has links)
En Europe, suite à la fermeture de nombreux sites sidérurgiques, une utilisation croissante de laitiers de haut-fourneau d’origine et d’âge variés voit le jour depuis plusieurs années. Cette évolution conduit à une diversification de la composition chimique et minéralogique des laitiers. Connaître l’influence de ces caractéristiques sur la réactivité des laitiers utilisés en substitution du clinker dans les ciments de haut-fourneau (CEM III) devient, dès lors, primordial pour assurer les performances de tels ciments.<p><p>Dans ce contexte, le présent travail a pour but d’investiguer l’influence de la composition chimique et de l’âge des laitiers sur leur réactivité tant par des essais physico-mécaniques que par une caractérisation physico-chimique et minéralogique de CEM III/B à différentes échéances d’hydratation. L’effet néfaste du vieillissement des laitiers est clairement mis en exergue et son impact diffère selon la composition chimique de départ du laitier. Les ions aluminium engendrent une accélération de l’hydratation et une amélioration des résistances physico-mécaniques à jeune âge mais, à long terme, ils conduisent à une perte de ces dernières. Concernant l’influence des ions titane dans les laitiers, la tendance générale observée est une diminution des performances physico-mécaniques.<p><p>Sur base de ces résultats, une évaluation de la représentativité de moyens accélérés d’estimation de la réactivité des laitiers est effectuée. Il est mis en évidence que seules les mesures de résistances physico-mécaniques classiques permettent d’évaluer correctement la réactivité des différents laitiers.<p><p>Une évaluation de la détermination de la teneur en constituants de CEM III/B par la méthode Rietveld est menée par comparaison avec la méthode de dissolution sélective de la norme EN 196-4 et le dosage des constituants par pesée. Moyennant une utilisation adaptée de cette méthode, les résultats obtenus à l’aide de celle-ci sont très encourageants.<p><p><p>In Europe, following the closure of many steel plants, an increased use of blast furnace slag (BFS) of various age and origin was born for several years. This evolution leads to a diversification of the chemical and mineralogical composition of the BFS. Knowing the influence of these characteristics on the reactivity of slag used in substitution of clinker in blast-furnace cement (CEM III) becomes, therefore, crucial to ensure the performance of such cements. <p><p>In this context, this work aims to investigate the influence of chemical composition and age of BFS on their reactivity by both physico-mechanical and physico-chemical and mineralogical characterization of CEM III/B at different times of hydration. The adverse effect of ageing of BFS is clearly highlighted and its impact varies depending on the chemical composition of the BFS. Aluminum ions generate an acceleration of the hydration and improve mechanical strength at early age, but at long term, they lead to a loss of the strength. Regarding the influence of titanium ions in the BFS, the general trend is a decrease of the physical and mechanical performance.<p><p>Based on these results, an assessment of the representativeness of accelerated means of estimating, the BFS reactivity is done. It is emphasized that only measures of physical and conventional mechanical strength can accurately assess the reactivity of different BFS. <p><p>An evaluation of the determination of the amount of CEM III/B components by the Rietveld method is based upon comparison with the selective dissolution method from the EN 196-4 norm and components determination by weight. Through appropriate use of this method, the results obtained are very encouraging.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Page generated in 0.1045 seconds