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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.
1

Joule heating as a smart approach in enhancing early strength development of mineral-impregnated carbon-fibre composites (MCF) made with geopolymer

Junger, Dominik, Liebscher, Marco, Zhao, Jitong, Mechtcherine, Viktor 04 March 2023 (has links)
The article at hand presents a novel approach to accelerating the early strength development of mineralimpregnated carbon-fibre composites (MCF) by electrical Joule heating. MCF were produced with a metakaolin-based geopolymer suspension and subsequently cured using Ohmic heating under systemically varied voltages and durations. The MCF produced were characterised in respect of their mechanical and morphological properties. Threepoint-bending and uniaxial tension tests yielded significant enhancement of MCF mechanical properties due to curing within only a few hours. Thermogravimetric analysis (TGA), mercury intrusion porosimetry (MIP), environmental scanning electron microscope (ESEM) as well as micro-computed tomography (μCT) confirmed advanced geopolymerisation by the electrical heating process and a strong sensitivity to parameter selection. After only two hours of resistance heating MCF could demonstrate tensile strength of up to 2800 MPa, showing the great potential for applying the Joule effect as a possibility to enhance the strength development of geopolymer-based MCF. Moreover, the applied method offers a huge potential to manufacture automated fast out-of-oven cured MCF with a variety of shapes and dimensions.
2

Causas múltiplas de morte: formas de apresentação e métodos de análise / Multiple causes of death: presentation forms and methods of analysis

Santo, Augusto Hasiak 17 March 1989 (has links)
RESUMO As informações sobre a mortalidade são tradicionalmente uma importante fonte de dados para estudos epidemiológicos, demográficos e para o planejamento em saúde. As estatísticas de mortalidade por causa são usualmente apresentadas segundo a causa básica de morte; a cada óbito corresponde uma só causa. Este método tem sofrido criticas devido a algumas de suas limitações, principalmente em relação às doenças crônicas quando, geralmente, estão presentes várias causas no momento da morte e apenas a básica é selecionada. As estatísticas de mortalidade segundo as causas múltiplas de morte se apresentam como um método alternativo para o estudo das causas de morte. A introdução dos computadores permitiu o desenvolvimento nos Estados Unidos de um sistema automático para classificar além da causa básica todos os demais diagnósticos mencionados nos atestados de óbito. Esse sistema, denominado ACME (Automated Classification of Medical Entities) amplia muito as possibilidades do uso das estatísticas de mortalidade e desde 1983 vem sendo utilizado no processamento de dados sobre os óbitos ocorridos no Estado de São Paulo. O presente trabalho discute a potencialidade do uso das causas múltiplas de morte para o estudo da mortalidade e apresenta algumas formas para a tabulação e a análise destas estatísticas exemplificadas com o arquivo de dados sobre os óbitos ocorridos em 1983 no Estado de São Paulo. Por meio da análise do número de diagnósticos informados na declaração de óbito mostrou-se um número médio maior dos mesmos em relação aos achados em trabalhos acadêmicos realizados com óbitos de períodos anteriores. 0 estudo das menções de todos os diagnósticos permitiu evidenciar a importância relativa maior de certas causas selecionadas como causa básica menos frequentemente. A análise das associações das causas de morte mostrou a importância do inter-relacionamento das doenças na determinação de morte e sugeriu outros usos das causas múltiplas. A distribuição conjunta das causas externas de morte com os dados sobre a natureza da lesão e a análise desta última segundo o sexo e a idade apresentam-se como nova perspectiva para a compreensão das mortes violentas. O levantamento e a discussão de questões metodológicas sugerem novas áreas de investigação para o estudo das causas múltiplas de morte / SUMMARY Informations about mortality are traditionally an important source of data for epidemiologic and demographic studies as well as for health planning. Mortality statistics based on causes have been derived from the underlying cause of death, implying that for each dead person only one cause is presented. These statistics have been criticised on account of their limitations, mainly when chronic diseases are considered and several causes are responsible for the death. Multiple cause mortality statistics represent an alternative method for the study of causes of death. The advent of computers made possible, in the United States, the development of an automated system for selecting the underlying cause of death as well as for coding all the reported conditions on the death certificate. This system, called ACME (Automated Classification of Medical Entities), greatly enlarges the possibilities of mortality statistics and it is used since 1983 to produce mortality data in the State of São Paulo. This thesis discusses the potential use of multiple cause of death for mortality studies and present some ways of its tabulations and analysis through examples which use the data file of death that occurred in 1983 in the State of São Paulo. The tabulation of the number of different diagnoses reported on the death certificate showed that its median number has increased when compared with the results of academic studies undertaken in other periods of time. The study of all mentions of the reported diagnoses depicted the greater importance of some causes of death infrequently selected as the underlying cause of death. The analysis of associations of causes of death revealed the importance of the combination of diseases to the determination of the death and allowed suggestions for other applications of multiple cause data. The cross tabulation of external causes of death with data related to the nature of injury and the analysis of the nature of injury by age and sex enhance new perspectives for the description and understanding of violent deaths. Methodological questions raised and discussed in this thesis suggest new areas of investigation for the study of multiple causes of death
3

Causas múltiplas de morte: formas de apresentação e métodos de análise / Multiple causes of death: presentation forms and methods of analysis

Augusto Hasiak Santo 17 March 1989 (has links)
RESUMO As informações sobre a mortalidade são tradicionalmente uma importante fonte de dados para estudos epidemiológicos, demográficos e para o planejamento em saúde. As estatísticas de mortalidade por causa são usualmente apresentadas segundo a causa básica de morte; a cada óbito corresponde uma só causa. Este método tem sofrido criticas devido a algumas de suas limitações, principalmente em relação às doenças crônicas quando, geralmente, estão presentes várias causas no momento da morte e apenas a básica é selecionada. As estatísticas de mortalidade segundo as causas múltiplas de morte se apresentam como um método alternativo para o estudo das causas de morte. A introdução dos computadores permitiu o desenvolvimento nos Estados Unidos de um sistema automático para classificar além da causa básica todos os demais diagnósticos mencionados nos atestados de óbito. Esse sistema, denominado ACME (Automated Classification of Medical Entities) amplia muito as possibilidades do uso das estatísticas de mortalidade e desde 1983 vem sendo utilizado no processamento de dados sobre os óbitos ocorridos no Estado de São Paulo. O presente trabalho discute a potencialidade do uso das causas múltiplas de morte para o estudo da mortalidade e apresenta algumas formas para a tabulação e a análise destas estatísticas exemplificadas com o arquivo de dados sobre os óbitos ocorridos em 1983 no Estado de São Paulo. Por meio da análise do número de diagnósticos informados na declaração de óbito mostrou-se um número médio maior dos mesmos em relação aos achados em trabalhos acadêmicos realizados com óbitos de períodos anteriores. 0 estudo das menções de todos os diagnósticos permitiu evidenciar a importância relativa maior de certas causas selecionadas como causa básica menos frequentemente. A análise das associações das causas de morte mostrou a importância do inter-relacionamento das doenças na determinação de morte e sugeriu outros usos das causas múltiplas. A distribuição conjunta das causas externas de morte com os dados sobre a natureza da lesão e a análise desta última segundo o sexo e a idade apresentam-se como nova perspectiva para a compreensão das mortes violentas. O levantamento e a discussão de questões metodológicas sugerem novas áreas de investigação para o estudo das causas múltiplas de morte / SUMMARY Informations about mortality are traditionally an important source of data for epidemiologic and demographic studies as well as for health planning. Mortality statistics based on causes have been derived from the underlying cause of death, implying that for each dead person only one cause is presented. These statistics have been criticised on account of their limitations, mainly when chronic diseases are considered and several causes are responsible for the death. Multiple cause mortality statistics represent an alternative method for the study of causes of death. The advent of computers made possible, in the United States, the development of an automated system for selecting the underlying cause of death as well as for coding all the reported conditions on the death certificate. This system, called ACME (Automated Classification of Medical Entities), greatly enlarges the possibilities of mortality statistics and it is used since 1983 to produce mortality data in the State of São Paulo. This thesis discusses the potential use of multiple cause of death for mortality studies and present some ways of its tabulations and analysis through examples which use the data file of death that occurred in 1983 in the State of São Paulo. The tabulation of the number of different diagnoses reported on the death certificate showed that its median number has increased when compared with the results of academic studies undertaken in other periods of time. The study of all mentions of the reported diagnoses depicted the greater importance of some causes of death infrequently selected as the underlying cause of death. The analysis of associations of causes of death revealed the importance of the combination of diseases to the determination of the death and allowed suggestions for other applications of multiple cause data. The cross tabulation of external causes of death with data related to the nature of injury and the analysis of the nature of injury by age and sex enhance new perspectives for the description and understanding of violent deaths. Methodological questions raised and discussed in this thesis suggest new areas of investigation for the study of multiple causes of death
4

Mineral-impregnated carbon fiber (MCF) reinforcements based on geopolymer

Zhao, Jitong 29 February 2024 (has links)
Carbon concrete composites (C³) hold promise as a material class for constructing lightweight, durable, and sustainable structures. State-of-the-art carbon fiber-reinforced polymer (CFRP) reinforcement comprises infinite multifilament bundles embedded in a polymeric matrix, en-suring adequate load transfer and process robustness, yet it undergoes considerable degrada-tion under elevated temperatures or harsh service conditions. Instead, the success of mineral-impregnated carbon fibers (MCFs) stems from their structural flexibility, inherent heat re-sistance, and outstanding compatibility with cementitious substrates. Geopolymers (GPs) have recently emerged as a viable coating alternative due to a unique combination of many advantages, e.g., sustainability, source diversity, long early-age processing time, synthesis by controlled low-temperature activation and a wide range of temperature resistance. This work aims to develop and test fast-setting MCF composites and associated processing technologies, which hold significant importance for industrial applications and structural fire safety. As a result of the novelty of mineral impregnation technology, challenges regarding the process chain and mixture must be mastered to explore the full material potential before the technology is translated to key markets. The introductory chapter offers a comprehensive review of fiber-reinforced geopolymer (FRG) systems in response to temperature influences. The concept development is grounded in a systematic investigation of several interrelated, critical processing aspects of GP impregnation, focusing on processing quality and strength evolution. This investigation is conducted alongside an automated and continuous impregna-tion technology. Findings from numerous experiments revealed that targeted thermal curing profoundly influ-enced the mechanical properties and microstructure of the GP matrices and resulting MCFs. Hereby, rapid setting and high early-age strength of MCF, comparable to conventional CFRPs, were achieved within the first several hours of heat curing. The ability of aluminosili-cate particles to penetrate a dense fiber bundle was studied by applying fly ash (FA) with a systematically varied particle size distribution. Thereby, the max. particle size close to the same range of diameter of individual filament proved to be the most efficient, improving both the mechanical performance of MCF and its bond to concrete. Furthermore, an experimental campaign on the role of fiber sizing agents in processing quality and final composite perfor-mance was conducted. The respective impregnation quality and quantity were comprehen-sively explained by varied yarn spreading behavior and wettability, resulting in apparent dif-ferences in filament-matrix morphology and mechanical performance of MCF. To achieve high shape stability, packing density, and tailor-bond characteristics, the effect of surface pro-filing and prototypical winding technology on MCF was investigated. Finally, the bond quality of the MCF was validated through yarn pull-out tests in GP concrete at elevated temperatures and compared with available CFRP. These tests generated parame-ters related to bond behavior, which were then used to construct a three-dimensional numeri-cal model. Based on proper parametric calibrations, good agreement between numerical and experimental characterizations was achieved to predict the material's performance for future applications.:1 Introduction 1 1.1 Motivation 1 1.2 Objectives of the thesis 5 1.3 Thesis structure 7 2 Publications 11 2.1 A review of the role of elevated temperatures on the mechanical properties of fiber-reinforced geopolymer (FRG) composites 12 2.2 Development and testing of fast curing, mineral-impregnated carbon fiber (MCF) reinforcements based on metakaolin-made geopolymers 37 2.3 Mineral-impregnated carbon-fiber (MCF) composites made with differently sized fly-ash geopolymers for durable light weight and high temperature applications. 50 2.4 Role of sizing agent on the microstructure morphology and mechanical properties of mineral-impregnated carbon-fiber (MCF) reinforcement made with geopolymers 66 2.5 Effect of surface profiling on the mechanical properties and bond behaviour of mineral-impregnated, carbon-fibre (MCF) reinforcement based on geopolymer 80 2.6 Temperature-dependent pull-out behavior of geopolymer concrete reinforced with polymer- or mineral-impregnated carbon fiber composites: an experimental and numerical study. 94 3 Summary and Outlook 108 3.1 Summary of the research work 108 3.2 Outlook 113 References 119 Appendix A IV Appendix B VI / Der Verbundwerkstoff Carbonbeton ist eine vielversprechende Materialklasse für den Bau von leichtgewichtigen, langlebigen und nachhaltigen Strukturen. Hochmoderne Bewehrungen aus Carbonfaser-verstärkte Kunststoffen (CFK) werden durch die Imprägnierung von Endlos-faserbündeln mit einer Polymermatrix hergestellt, was ausreichende Lastübertragungskapazi-tät und Prozessrobustheit gewährleistet, und jedoch durch hohe Temperaturen oder raue Um-gebungen erheblich zerstört wird. Stattdessen resultiert der Erfolg mineralimprägnierter Car-bonfasern (MCFs) aus ihrer strukturellen Flexibilität, inhärenten Wärmebeständigkeit und hervorragenden Kompatibilität mit zementären Substraten. Geopolymere (GPs) haben sich kürzlich als praktikable Beschichtungsalternative herausgestellt, aufgrund einer einzigartigen Kombination vieler Vorteile, wie Nachhaltigkeit, Quellenvielfalt, ausreichendes Verarbei-tungsfenster, Synthese durch kontrollierte thermische Aktivierung bei niedrigen Temperatu-ren und Hitzebeständigkeit. Die vorliegende Arbeit zielt auf die Entwicklung und Erprobung schnell abbindender MCF-Verbundwerkstoffe und zugehöriger Verarbeitungstechnologien ab, was für industrielle An-wendungen und den baulichen Brandschutz von großer Bedeutung ist. Aufgrund der Neuar-tigkeit der mineralischen Imprägnierungstechnologie müssen Herausforderungen in Bezug auf die Prozesskette und Mischung gemeistert werden, um das volle Materialpotenzial zu erkunden, bevor die Technologie auf Schlüsselmärkte übertragen wird. Dementsprechend gibt das einleitende Kapitel einen umfassenden Überblick über faserverstärkte Geopolymer (FRG)-Systeme unter Temperatureinwirkung. Das Entwicklungskonzept baut auf einer sy-stematischen Untersuchung mehrerer zusammenhängender, wichtiger Verarbeitungsaspekte der GP-Imprägnierung in Bezug auf Verarbeitungsqualität und Festigkeitsentwicklung von der Mikro- bis zur Makroskala und in Verbindung mit einer automatisierten und kontinuierli-chen Fertigungstechnologie auf. Ergebnisse zahlreicher Experimente zeigten, dass gezielte Wärmehärtung die mechanischen Eigenschaften und Mikrostruktur der GP-Matrizen und resultierenden MCFs nachhaltig be-einflußt. Hierdurch wurde eine schnelle Aushärtung und hohe Festigkeit von MCF innerhalb der ersten Stunden der Wärmebehandlung erreicht, und zwar vergleichbar mit konventionel-len CFRPs. Die Eindringfähigkeit von Aluminosilikatpartikeln in ein dichtes Faserbündel wurde durch die Anwendung von Flugasche (FA) mit systematisch variierter Partikelgrößen-verteilung untersucht. Dabei erwies sich die maximale Partikelgröße, die nahe dem Durch-messer einzelner Filamente liegt, als am effizientesten. Sie verbesserte sowohl die mechani-sche Leistung von MCF als auch seine Bindung an Beton. Darüber hinaus wurde eine expe-rimentelle Kampagne zur Rolle der Faserschlichte auf die Verarbeitungsqualität und die end-gültige Verbundleistung durchgeführt. Die jeweilige Imprägnierungsqualität wurde umfas-send durch ein unterschiedliches Spreizungsverhalten und Benetzbarkeit des Garns erklärt, was zu deutlichen Unterschieden in der Filament-Matrix-Verteilung und mechanischen Ei-genschaften von MCF führte. Zur Verbesserung der Formstabilität, Packungsdichte und ge-zielten Abstimmung der Verbundeigenschaften im Beton wurde der Effekt der Oberflächen-profilierung und prototypischen Wickeltechnik auf MCF untersucht. Schließlich wurde die Verbundqualität der MCF durch den Garnauszugversuch in GP-Beton bei erhöhten Temperaturen validiert und mit einer verfügbaren CFK-Bewehrung verglichen. Diese Tests generierten auf das Verbundverhalten bezogene Parameter, die dann zur Formu-lierung eines dreidimensionalen numerischen Modells verwendet wurden. Durch angemesse-ne parametrische Kalibrierungen wurde eine gute Übereinstimmung zwischen numerischen und experimentellen Charakterisierungen erreicht, um die Leistung des Materials für zukünf-tige Anwendungen vorherzusagen.:1 Introduction 1 1.1 Motivation 1 1.2 Objectives of the thesis 5 1.3 Thesis structure 7 2 Publications 11 2.1 A review of the role of elevated temperatures on the mechanical properties of fiber-reinforced geopolymer (FRG) composites 12 2.2 Development and testing of fast curing, mineral-impregnated carbon fiber (MCF) reinforcements based on metakaolin-made geopolymers 37 2.3 Mineral-impregnated carbon-fiber (MCF) composites made with differently sized fly-ash geopolymers for durable light weight and high temperature applications. 50 2.4 Role of sizing agent on the microstructure morphology and mechanical properties of mineral-impregnated carbon-fiber (MCF) reinforcement made with geopolymers 66 2.5 Effect of surface profiling on the mechanical properties and bond behaviour of mineral-impregnated, carbon-fibre (MCF) reinforcement based on geopolymer 80 2.6 Temperature-dependent pull-out behavior of geopolymer concrete reinforced with polymer- or mineral-impregnated carbon fiber composites: an experimental and numerical study. 94 3 Summary and Outlook 108 3.1 Summary of the research work 108 3.2 Outlook 113 References 119 Appendix A IV Appendix B VI
5

Development and testing of fast curing, mineral-impregnated carbon fiber (MCF) reinforcements based on metakaolin-made geopolymers

Zhao, Jitong, Liebscher, Marco, Michel, Albert, Junger, Dominik, Trindade, Ana Carolina Constâncio, Silva, Fláviode Andrade, Mechtcherine, Viktor 28 November 2022 (has links)
Mineralisch getränkte Carbonfasern (MCF) stellen eine vielversprechende Alternative zu herkömmlichen Stahlbewehrung in Beton dar. Für eine effiziente industrielle Herstellung von MCF muss eine ausreichende Verarbeitungszeit für die Imprägniersuspension gewährleistet sein. In der vorliegenden Untersuchung wurde zu diesem Zweck ein aus Metakaolin hergestelltes Geopolymer (GP) entwickelt und getestet. Die Tränkung von Carbonfasergarnen wurde kontinuierlich und automatisiert durchgeführt. Anschließend wurden die MCF bei 75 °C wärmebehandelt, um die Reaktionsprozesse zu beschleunigen. Die mechanische Leistung von MCF nahm im Verlauf des Aushärtungsprozesses von 2 auf 8 Stunden allmählich zu, was auf das größere Ausmaß der Geopolymerisation zurückzuführen ist. Bei einer solchen verlängerten Aushärtung zeigten thermogravimetrische und mikroskopische Analysen zwar eine stärkere 'reagierte' Mikrostruktur, aber auch einen höheren Gehalt an Hohlräumen. Nach 8-stündigen Erhitzen erreichten die Zugfestigkeit und der Young-Modul von MCF 2960 MPa bzw. 259 GPa, bezogen auf die Garnquerschnittsfläche.:Abstract Schlagwörter 1. Einleitung 2. Experimentelles Programm 2.1. Materialien 2.2. Herstellung von MCF 2.3. Testen der Geopolymermatrix 2.4. Mechanische Prüfung von MCF 2.5. Morphologische Charakterisierung 3. Ergebnisse und Diskussion 3.1. Charakterisierung der Geopolymermatrix 3.2. Hergestellte MCF mit Geopolymer und Wärmebehandlung bei 75 °C. 3.3. Chemische und morphologische Analyse 4. Schlussfolgerung Erklärung des konkurrierenden Interesses Literaturen / Mineral-impregnated, carbon fiber composites (MCF) are a promising alternative to conventional concrete reinforcements. For the efficient industrial production of MCF, sufficient processing time for the impregnation suspension must be ensured. In the present investigation, a metakaolin-made geopolymer (GP) has been developed and tested for this purpose. The impregnation of carbon-fiber yarns was performed continuously and automated. Subsequently, the MCF were heat-treated at 75 °C to accelerate the reaction processes. The mechanical performance of MCF gradually increased in the advancement of the curing process from 2 to 8 h, which is attributed to the greater extent of geopolymerization. In such extended curing, thermogravimetric and microscopic analysis showed indeed a more “reacted” microstructure but also a higher content of voids. After heating for 8 h, the tensile strength and Young's modulus of MCF reached 2960 MPa and 259 GPa, respectively, when related to the yarn cross-sectional area.:Abstract Schlagwörter 1. Einleitung 2. Experimentelles Programm 2.1. Materialien 2.2. Herstellung von MCF 2.3. Testen der Geopolymermatrix 2.4. Mechanische Prüfung von MCF 2.5. Morphologische Charakterisierung 3. Ergebnisse und Diskussion 3.1. Charakterisierung der Geopolymermatrix 3.2. Hergestellte MCF mit Geopolymer und Wärmebehandlung bei 75 °C. 3.3. Chemische und morphologische Analyse 4. Schlussfolgerung Erklärung des konkurrierenden Interesses Literaturen
6

L'encadrement juridique de la gestion électronique des données médicales. / Legal framework for the electronic management of medical data

Etien-Gnoan, N'Da Brigitte 18 December 2014 (has links)
La gestion électronique des données médicales consiste autant dans le simple traitement automatisé des données personnelles que dans le partage et l'échange de données relatives à la santé. Son encadrement juridique est assuré, à la fois, par les règles communes au traitement automatisé de toutes les données personnelles et par celles spécifiques au traitement des données médicales. Cette gestion, même si elle constitue une source d'économie, engendre des problèmes de protection de la vie privée auxquels le gouvernement français tente de faire face en créant l'un des meilleurs cadres juridiques au monde, en la matière. Mais, de grands chantiers comme celui du dossier médical personnel attendent toujours d'être réalisés et le droit de la santé se voit devancer et entraîner par les progrès technologiques. Le développement de la télésanté bouleverse les relations au sein du colloque singulier entre le soignant et le soigné. L'extension des droits des patients, le partage de responsabilité, l'augmentation du nombre d'intervenants, le secret médical partagé constituent de nouveaux enjeux avec lesquels il faut, désormais compter. Une autre question cruciale est celle posée par le manque d'harmonisation des législations augmentant les risques en cas de partage transfrontalier de données médicales / The electronic management of medical data is as much in the simple automated processing of personal data in the sharing and exchange of health data . Its legal framework is provided both by the common rules to the automated processing of all personal data and those specific to the processing of medical data . This management , even if it is a source of economy, creates protection issues of privacy which the French government tries to cope by creating one of the best legal framework in the world in this field. However , major projects such as the personal health record still waiting to be made and the right to health is seen ahead and lead by technological advances . The development of e-health disrupts relationships within one dialogue between the caregiver and the patient . The extension of the rights of patients , sharing responsibility , increasing the number of players , the shared medical confidentiality pose new challenges with which we must now count. Another crucial question is posed by the lack of harmonization of legislation increasing the risks in cross-border sharing of medical

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