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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

Models and Inference for Multivariate Spatial Extremes

Vettori, Sabrina 07 December 2017 (has links)
The development of flexible and interpretable statistical methods is necessary in order to provide appropriate risk assessment measures for extreme events and natural disasters. In this thesis, we address this challenge by contributing to the developing research field of Extreme-Value Theory. We initially study the performance of existing parametric and non-parametric estimators of extremal dependence for multivariate maxima. As the dimensionality increases, non-parametric estimators are more flexible than parametric methods but present some loss in efficiency that we quantify under various scenarios. We introduce a statistical tool which imposes the required shape constraints on non-parametric estimators in high dimensions, significantly improving their performance. Furthermore, by embedding the tree-based max-stable nested logistic distribution in the Bayesian framework, we develop a statistical algorithm that identifies the most likely tree structures representing the data's extremal dependence using the reversible jump Monte Carlo Markov Chain method. A mixture of these trees is then used for uncertainty assessment in prediction through Bayesian model averaging. The computational complexity of full likelihood inference is significantly decreased by deriving a recursive formula for the nested logistic model likelihood. The algorithm performance is verified through simulation experiments which also compare different likelihood procedures. Finally, we extend the nested logistic representation to the spatial framework in order to jointly model multivariate variables collected across a spatial region. This situation emerges often in environmental applications but is not often considered in the current literature. Simulation experiments show that the new class of multivariate max-stable processes is able to detect both the cross and inner spatial dependence of a number of extreme variables at a relatively low computational cost, thanks to its Bayesian hierarchical representation. These innovative methods and models are implemented to study the concentration maxima of various air pollutants and how these are related to extreme weather conditions for a number of sites in California, one of the most populated and polluted states of the US. As a result, we provide comprehensive measures of air quality that can be used by communities and policymakers worldwide to better assess and manage the health, environmental and financial impacts of air pollution extremes.
2

Modification of native and waste starch by depolymerization and cationization:utilization of modified starch in binding of heavy metal ions from an aqueous solution

Lappalainen, K. (Katja) 17 November 2015 (has links)
Abstract Starch is one of the most abundant polysaccharides found in nature and is widely utilized in various fields of industry. Due to the complex structure of native starch it is insoluble in most organic solvents and needs modification prior utilization. In this study, ionic liquids (ILs), modern green chemistry alternatives for common solvents were used as reaction media in starch modification. At first various starch species were depolymerized in 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) with p-TsOH as a catalyst. Microwave activation or conventional bath heating were used as heating methods while HPLC-ELSD was used as an analytical method. All studied starch species depolymerized similarly into water-soluble starch oligomers while microwave activation shortened the depolymerization time considerably compared to oil bath heating. Barley starch was chosen for further experiments, in which various ILs were studied as potential media for starch dissolution and depolymerization. Results suggested that both the anion and the cation part of the IL had an effect on the dissolution and depolymerization of barley starch. After the depolymerization reactions, the depolymerized barley starch was further modified by cationization. [AMIM]Cl was used as the reaction media, microwave activation as the heating method while HPLC-ELSD, 1H NMR and elemental analysis were used as analytical methods. The modified products had DS values from 0.2 to 0.5 depending on the reaction conditions. The products were studied as potential binding agents for heavy metal ions which showed that moderately substituted modified starch (DS 0.4) could be used to bind Cu(II), Fe(III) and Zn(II) ions from an aqueous solution. Finally, potato peel waste was studied as an alternative starch source to produce cationized starch for wastewater purification. Peel waste was pre-treated by alkaline depolymerization after which it was cationized in a water solution to produce cationized products with DS from 0 to 0.35. The cationized peel waste products were studied preliminary as binding agents for Cu(II) ions from a water solution using ICP-OES as an analytical method. The results suggested that when the molar ratio between cationized waste starch and copper was 3:1, cationized waste starch was an effective binding agent for copper ions. / Tiivistelmä Tärkkelys on yksi yleisimmistä luonnossa esiintyvistä polysakkarideista. Sitä hyödynnetään useilla eri teollisuuden aloilla. Monimutkaisen rakenteensa vuoksi tärkkelys on liukenematon useimpiin orgaanisiin liuottimiin ja veteen, minkä vuoksi sitä täytyy modifioida ennen käyttöä. Tässä väitöstutkimuksessa tärkkelyksen modifioinnissa käytettiin ionisia nesteitä reaktioväliaineena. Tutkimuksen alussa eri tärkkelyslajeja depolymeroitiin 1-allyyli-3-metyyli-imidatsoliumkloridissa ([AMIM]Cl) katalyyttinä p-TsOH. Mikroaaltoaktivointia ja haudekuumennusta käytettiin vaihtoehtoisina lämmitysmenetelminä. Reaktion edistymistä ja tuotteiden muodostumista tutkittiin HPLC-ELSD -menetelmällä. Eri tärkkelyslajit depolymeroituivat samankaltaisesti vesiliukoisiksi, lyhytketjuisiksi tärkkelysoligomeereiksi. Mikroaaltoaktivointi lyhensi reaktioaikaa haudekuumennukseen verrattuna. Tutkimuksen seuraavassa vaiheessa tutkittiin ohratärkkelyksen liukoisuutta ja depolymeroitumista eri ionisissa nesteissä. Tulosten perusteella ionisen nesteen sekä anioni- että kationiosa vaikuttivat tärkkelyksen liukenemiseen. Depolymeroidun ohratärkkelyksen modifiointitutkimuksia jatkettiin [AMIM]Cl:ssa kationisoinnilla. Lämmitysmenetelmänä käytettiin mikroaaltoaktivointia. Tuotteet tutkittiin käyttäen alkuaineanalyysiä sekä HPLC-ELSD- että 1H NMR-tekniikoita. Kationisoitujen tuotteiden substituutioaste (DS) vaihteli reaktio-olosuhteista riippuen välillä 0.2–0.5. Saatuja tuotteita tutkittiin raskasmetalli-ionien sitomisessa vesiliuoksesta. Havaittiin, että kohtalaisesti substituoitu (DS 0.4) modifioitu tärkkelys sitoi Cu(II)-, Fe(III)- ja Zn(II)-ioneja vesiliuoksesta. Tutkimuksen loppuosassa tutkittiin perunan kuorijätettä vaihtoehtoisena tärkkelyslähteenä kationisoidun tärkkelyksen valmistamisessa. Kuorijäte esikäsiteltiin kuumentamalla se emäksisessä etanoliliuoksessa, minkä jälkeen sille suoritettiin kationisointi vesiliuoksessa. Kationisten tuotteiden substituutioasteet vaihtelivat välillä 0–0.35. Tuotteiden soveltuvuutta Cu(II)-ionien sitomiseen vesiliuoksesta tutkittiin ICP-OES -menetelmän avulla. Alustavien tulosten mukaan kationisoitu jätetärkkelys sitoi kupari-ioneja vedestä, kun tärkkelyksen ja kuparin moolisuhde oli 3:1.
3

Projeto Educativo E Político-Pedagógico Da Escola De Ensino Médio: Tradições E Contradições Na Gestão E Na Formação Para O Trabalho / The Midlle Schoool Educational and Politic Pedagogic Project: traditions and contradictions in the managment and formation for work.

RAMOS, Jeannette Filomeno Pouchain January 2009 (has links)
RAMOS, Jeannette Filomeno Pouchain. Projeto educativo e político-pedagógico da escola De ensino médio: tradições e contradições na gestão e na formação para o trabalho. 2009. 245f. Tese (Doutorado em Educação) – Universidade Federal do Ceará, Faculdade de Educação, Programa de Pós-Graduação em Educação Brasileira, Fortaleza-CE, 2009. / Submitted by Maria Josineide Góis (josineide@ufc.br) on 2012-07-09T11:46:49Z No. of bitstreams: 1 2009_Tese_JFPRamos.pdf: 2192405 bytes, checksum: 71c4d8335d8c1d60c3331ea87534ab26 (MD5) / Approved for entry into archive by Maria Josineide Góis(josineide@ufc.br) on 2012-07-13T11:18:44Z (GMT) No. of bitstreams: 1 2009_Tese_JFPRamos.pdf: 2192405 bytes, checksum: 71c4d8335d8c1d60c3331ea87534ab26 (MD5) / Made available in DSpace on 2012-07-13T11:18:44Z (GMT). No. of bitstreams: 1 2009_Tese_JFPRamos.pdf: 2192405 bytes, checksum: 71c4d8335d8c1d60c3331ea87534ab26 (MD5) Previous issue date: 2009 / The Brazilian education, founded by the logic submission of the educational project from the Jesuits, and the influences from the French, English and Americans, passed on to be considered a national problem with the proclamation of the republic in 1980. The attempt to regulate and to consolidate the social function propaedeutics, which denies the work, the industrialization who demanded the instrumental education for work and the reestablishment of the democracy in the state which reorganized the flexible production and impose the formation of a new type of worker (KUENZER, 1998) presents contradictories movements. In agreement with transformation the scientific technical conception of organization adopted participative democratic mechanism. Recognizing the contradiction in keeping distinct types of logic and the tendency of the liberal logic over the social logic, the challenger of the work management is to reverse this premise. As an alternative to the educational middle class project, the polytechnic education proposes to overcome the dual structure and history by omni lateral formation (SAVIANI, 2003). The elementary and middle school should be guided by the work as an excellent base for education (PISTRAK, 2005). The school, known as the work product of man, should be linked to school life as a social transformation combined with school education with material production and to promote self and social emancipation. In context, the general objective is to analyze the experience of reorganizing the educational work in creation of the politic pedagogic project of middle school, identifying perspectives, limits, possibilities, and resistances. The specifics objectives are to examine the evolution of the educational project in the social politic and economic history of Brazil, highlighting the management of school work and the formation of the young for work; analyze fundamentals, intentions and practices which guide the politic pedagogic project and identify and analyze the limits, possibilities and ways of group resistances in the management project. We choose as a theoretical methodological referential the Critic Theory and the method with materialistic history base. As instruments of qualitative and quantitative data collection we applied questionnaires, semi-structures interviews and focal groups. Among hypothesis should public school follow the educational project of middle class or should it follow the lines of vocational extent, instrumental; to attend to middle class project of the popular sector? The hard format of school has accomplished changes in the lines of directions? The politic pedagogic project working at Liceu do Maracanaú establish four pillars which reorganize the work in the school bearing in mind the full formation of the young. This school thinks, conceives and evaluates opposition to the others schools; it breaks with the traditional format of the work organization. The multiples intelligences are understood as principles, the project of work is the means to transformation of popular knowledge to the scientific knowledge with practice and social application of ideas in development of competencies and abilities, as means an half-yearly organizational and the evaluation as the learning observation. Scientific initiation in middle level education attends the interests of the school, highlighting the talents, improving the indicators and presenting results. This project is contradictory because the fundamentals and practice pedagogic reassures the principles of the traditional format and the process of schooling. This way the study confirms that is possible reorganize the work and this is done by the politic pedagogic project (PPP). Faced with the new demands the schools find themselves in a cross road and their functionality is placed at doubt. As a result of this, we point out the crises of education, formation of young and the society. It is necessary to invest in the contradictions of the system and take possession of them to construct another, the opposite and reverse. It is up to the intellectuals and educators to do their job. / A educação brasileira, permeada pela lógica da submissão do projeto educativo dos jesuítas, das influências francesas, inglesas e dos Estados Unidos da América, passa a ser considerada como problema nacional com a Proclamação da República em 1890. As tentativas de regulamentação e consolidação da função social propedêutica, que nega o trabalho, a industrialização que demandou a educação instrumental para o trabalho e a redemocratização do Estado que reorganizou a produção em flexível e impõe a formação do novo tipo de trabalhador (KUENZER, 1998) apresentam movimentos contraditórios. Em consonância com estas transformações a concepção técnico-científica de organização adota mecanismos democráticos-participativos. Como alternativa ao projeto educativo burguês, a educação politécnica propõe superar a dualidade estrutural e histórica por meio da formação omnilateral (SAVIANI, 2003). A escola fundamental e média deve guiar-se pelo trabalho como base excelente da educação (PISTRAK, 2005), portanto, deve vincular a vida escolar com a transformação social combinando educação escolar com produção material e promover a auto-emancipação e a emancipação social. Neste contexto, o objetivo geral é analisar a experiência de reorganização do trabalho educativo na constituição do projeto político-pedagógico da escola de ensino médio, identificando perspectivas, limites, possibilidades e resistências. Os objetivos específicos são examinar a evolução do projeto educativo na história sociopolítica e econômica do Brasil, destacando a gestão do trabalho escolar e a formação do jovem para o trabalho; analisar os fundamentos, intencionalidades e práticas que norteiam o projeto político-pedagógico e identificar e analisar os limites, possibilidades e formas de resistência coletiva na gestão do projeto. Optamos como referencial teórico-metodológico pela Teoria Crítica e pelo método de base materialista-histórica. Como instrumento de coleta de dados quantitativos e qualitativos foram aplicados questionários, grupos focais e entrevistas semiestruturadas. Entre os questões levantadas destacamos se escola pública deve seguir o projeto educativo da burguesia – propedêutica – ou deve se pautar na dimensão profissionalizante, instrumental, por atender ao projeto burguês para o setor popular? A escola mineralizada tem conseguido ressignificar diretrizes? O projeto político-pedagógico (PPP) em curso no Liceu do Maracanaú estabelece quatro pilares que reorganizam o trabalho na escola tendo em vista a formação integral do jovem. Esta escola pensa concebe e avalia e na contramão da maioria das escolas, rompe com o formato tradicional de organização do trabalho. As inteligências múltiplas são compreendidas como princípio, os projetos de trabalho como meio para a transformação do saber popular para o saber científico com aplicação prática e social dos conteúdos no desenvolvimento de competências e habilidades, a organização semestral como meio e a avaliação como monitoramento da aprendizagem. A iniciação cientifica destaca os talentos, melhora os indicadores e apresenta resultados. Este projeto é contraditório, pois os fundamentos e a prática pedagógica reafirmam os princípios liberais e o processo de escolarização excludente. Deste modo, o estudo confirma que é possível reorganizar o trabalho e este se concretiza por intermédio do PPP. Diante destas novas demandas, as escolas se encontram numa encruzilhada e sua funcionalidade é colocada em dúvida. Como prognóstico, apontamos o aprofundamento da crise da educação, da formação do jovem e da sociedade. Urge investir nas contradições inerentes ao sistema, apropriar-se delas para construção do outro, do contrário. Cabe, portanto, aos intelectuais e educadores cumprirem com a sua tarefa.

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