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Made available in DSpace on 2015-05-14T12:17:13Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 9184343 bytes, checksum: fdcc9bd6eaff2c0eeac333df2ba9f163 (MD5) Previous issue date: 2014-08-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Brazilian semiarid presents a biotic and abiotic framework still little known scientifically, which ends up favoring the occurrence of environmental degradation, hallmark the set of existing landscapes, particularly in their areas of increased climatic dryness. This work was conducted in the municipality of Cabaceiras-PB, known as the least rainfall in Brazil, where there are also serious environmental impacts due to the occurrence of some natural processes and primarily through the use and occupation of land by agricultural and extractive activities, from beginning of the occupation of their territory. The overall objective of the research was to analyze the existing level of environmental degradation in the city, with the specific objectives, perform the physical-geographic diagnosis, analyze the vulnerability of landscape units associated with socioeconomic activities and analyze the relationship between historical and socioeconomic process use and occupation of land with environmental degradation. The methodology was based on geosystemic and ecodynamic theories, as well as the concepts and processes causing environmental degradation. For methodological procedures, geoprocessing and remote sensing, accompanied by field work to validate the responses were used. As results, it was concluded that the municipality is predominantly in a medium level of stability and vulnerability, prevailing morphogenesis on pedogenesis and 32.36% of the study area was considered degraded, in view of the loss of biomass between the periods of 1989 and 2005. From the standpoint of shares that can contain the degradation and improve environmental quality currently found, we sought to highlight some guidelines and existing public assistance programs, which, being well executed, can solve or at least ameliorate the situation. / O semiárido brasileiro apresenta um quadro biótico e abiótico ainda pouco conhecido cientificamente, o que acaba favorecendo a ocorrência de degradação ambiental, característica marcante no conjunto de paisagens existentes, particularmente em suas zonas de maior secura climática. Esse trabalho foi realizado no município de Cabaceiras-PB, conhecido como o de menor pluviosidade do Brasil, onde também existem sérios impactos ambientais devido a ocorrência de alguns processos naturais e principalmente através do uso e ocupação da terra por atividades agropecuárias e extrativistas, desde o início do processo de ocupação de seu território. O objetivo geral da pesquisa foi analisar o nível de degradação ambiental existente no município, tendo por objetivos específicos, realizar o diagnóstico físico-geográfico, analisar a vulnerabilidade das unidades de paisagem associadas às atividades socioeconômicas e analisar a relação do processo histórico e socioeconômico de uso e ocupação da terra com a degradação ambiental. A metodologia foi fundamentada nas Teorias Geossistêmica e Ecodinâmica, como também nos conceitos e processos causadores da degradação ambiental. Para os procedimentos metodológicos, foram utilizadas técnicas de geoprocessamento e sensoriamento remoto, acompanhadas de trabalhos de campo para validação das respostas obtidas. Como resultados, concluiu-se que o município se encontra, predominantemente, em um nível de estabilidade e vulnerabilidade média, prevalecendo a morfogênese sobre a pedogênese e que 32,36% da área de estudo foi considerada como degradada, tendo em vista a perda de biomassa entre os períodos de 1989 e 2005. Do ponto de vista das ações passíveis de conter a degradação e melhorar a qualidade ambiental encontrada atualmente, buscou-se destacar algumas diretrizes e programas de intervenções públicas existentes, as quais, sendo bem executadas, podem solucionar ou ao menos amenizar a situação existente.

Les technologies actuellement utilisées pour les moteurs diesel conduisent à la dégradation accélérée des constituants chimiques des lubrifiants, notamment des additifs non polymériques de type antioxydants, anti-usures, modificateurs de friction et de détergence.Nos travaux visent à identifier la nature des modifications chimiques de ces additifs au cours du fonctionnement moteur. Ainsi, un protocole analytique a été établi afin d’étudier qualitativement et quantitativement ces familles dans les lubrifiants.Ce protocole a ensuite été utilisé pour l’analyse d’huiles vieillies lors de tests sur banc moteur et d’essais réalisés en laboratoire. L'évolution de la composition chimique des lubrifiants, la nature des produits de dégradation formés, et les processus d'altération impliqués ont ainsi été étudiés, et des modèles cinétiques de la dégradation de chaque famille d’additifs ont été établis.Il ressort de notre étude que les processus mis en jeu dans l’altération des additifs en laboratoire ne reproduisent pas ceux existant lors du fonctionnement moteur, ce qui laisse envisager le développement d'expériences de laboratoire mieux adaptées. / Current technologies used for diesel engines lead to an accelerated degradation of the non-polymeric additives from lubricants, such as antioxidants, antiwear, friction modifiers and detergency additives.Our work intends to identify the nature of the chemical modifications undergone by such additives during engine functioning. In this respect, an analytical protocol has been developed in order to investigate qualitatively and quantitatively these compound families in engine oils. Following this, the analytical methodology has then been used to study oils altered during engine bench tests and laboratory experiments. Thus, the evolution of the chemical composition, the nature of the degradation products and the alteration processes have been considered. Furthermore, kinetic models have been established for each family of additives.It appears from this study that the processes implied in the alteration of the additives during laboratory tests do not reproduce those existing while engine running. Further laboratory experiments are needed in order to develop tests mimicking more closely the conditions occurring during engine functioning.

This master’s thesis deals with the problematics of influence of ionizing radiation on semiconductor devices and their properties. The aim of the thesis is to analyze the different types of radiation that can occur in the areas of application of these components. In the second part, the degradation processes are explored, with emphasis on the influence caused by the radiation dose. Also, the displacement damage and SEE effects are described, but just slightly, because they are not part of this work. The third part describes the device design process and harmful effects, that have to be considered during the design phase. In the forth and the fifth parts of this work were done modeling of radiation effects (influence of dose rate, Single-Event Upset and Total Ionizing Dose) in PSpice program and was carried out the possibility of designing a simple dosimeter with silicon diode. In conclusion, the results of the thesis are summarized and evaluated.

The diploma thesis introduces the reader to the problems of chemical sensors and the basics of degradation processes in materials of animal origin. It describes some types of sensors and their principles. Atmel ATmega328 microprocessor, its parameters and programming are described. In the next part of the thesis there is a proposal and production of equipment for monitoring of degradation processes in materials of animal origin. Sample sof chicken and milk were mesuared. From these measurements, the gas concentration values were determined, where samples can be considered suitable for consumation.

This work deals with issues of thin films, their behaviour in different enviroments and protection of theese films against unwanted degradation processes. Metal thin films are made by special physical or chemical methods in the presence of vacuum. Deposition is performed on properly cleaned substrate made of different materials, for example glass, ceramics or another metal. Theese films degrades under the influence of moisture, heat and other. There are several types of films on different bases made to prevent thin films against degradation.

The application of electrochemical methods for the characterization of colloidal quantum dots (QDs) attracts considerable attention as these methods may allow for monitoring of some crucial parameters, such as energetic levels of conduction and valence bands as well as surface traps and ligands under real conditions of colloidal solution. In the present work we extend the applications of cyclic voltammetry (CV) to in situ monitoring of degradation processes of water-soluble CdTe QDs. This degradation occurs under lowering of pH to the values around 5, i.e. under conditions relevant to bioimaging applications of these QDs, and is accompanied by pronounced changes of their photoluminescence. Observed correlations between characteristic features of CV diagrams and the fluorescence spectra allowed us to propose mechanisms responsible for evolution of the photoluminescence properties as well as degradation pathway of CdTe QDs at low pH.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The practice of irrigated agriculture represents an increase of agricultural productivity, especially for areas with water deficit. Lands are frequently characterized erroneously which, coupled with lacking conservation measures, imposes serious consequences for the environment. In reality, any land use and intensive soil management when carried out unsustainably, can result in degradation processes. This study aims to provide subsidies for a conservationist planning in the Irrigated Perimeter of Mirorós, based on the rational use of land and adequate soil management. The perimeter is located in a semi-arid region of Bahia State (Brazil), municipality of Ibipeba, micro-region of Irecê. The following methods were adopted to evaluate the perimeter: evaluation of the edapho-climatic land potential, evaluation of the land potential for irrigation, determination of rates of land use adequacy as well as the use of indicators of soil quality for two kinds of land use (with and without irrigation). Thereby it was possible to define priority areas for intervention regarding land use and soil management (projected for conservation, recovery or recovery/preservation) and to identify the main susceptibilities for degradation processes or for improvements in soil quality, which have proven fundamental for conservationist planning strategies. The results showed that irrigated agriculture resulting in changes in the classification of land and greater impairment of soil quality, especially due to the susceptibility to the processes of compaction, salinisation and sodification, when compared to other uses without irrigation. On the other hand, the irrigated soils showed greater susceptibility to improvements in fertility and acidification. In fact, the negative effects as well as the improvements in soil quality were noted, in a smaller scale, in soils with other usage without irrigation. In general, the land of the perimeter in Mirorós possesses the potential for general agricultural use or for irrigated agriculture, but there is urgent need for interventions in soil management, including necessities of conservation or priority conservation. Additional interventions in usage are needed in areas that are being used in excess of their potential, resulting in the recovery/priority preservation of these areas. Furthermore, there are existing demands for interventions both in usage and management, resulting in areas that are priority for recovery. The proposed methods can be considered essential tools for the conservation of the natural resources in the study area, contributing towards sustainability in an agricultural environment. / A prática da agricultura irrigada representa um incremento da produtividade agrícola, principalmente para regiões com deficiência de água. No entanto, muitas vezes, a classificação das terras ocorre de forma incorreta, aliada à falta de medidas de conservação, o que tem imposto sérias conseqüências ambientais. Na realidade, qualquer uso da terra e manejo intensivo do solo, quando de maneira não sustentável, pode acarretar em processos de degradação. Este trabalho objetiva fornecer subsídios ao planejamento conservacionista, no Perímetro Irrigado de Mirorós, com base no uso racional das terras e manejo adequado do solo. Esse perímetro está localizado no semi-árido baiano, município de Ibipeba, microrregião de Irecê (BA). Para tanto, são adotadas a Avaliação do Potencial Edafoclimático das Terras e a Avaliação do Potencial das Terras para Irrigação, são determinadas as taxas de adequação do uso das terras, além da utilização de indicadores de qualidade do solo para dois tipos de usos das terras (com irrigação e sem irrigação). Com isso, houve possibilidade de definir áreas prioritárias de intervenção quanto ao uso das terras e manejo do solo (destinadas para Conservação, Recuperação ou Recuperação/Preservação) e identificar as principais suscetibilidades aos processos de degradação ou às melhorias na qualidade dos solos, as quais se mostraram fundamentais como estratégias para o planejamento conservacionista. Os resultados mostraram que a agricultura irrigada vem causando mudanças nas classificações das terras e maior comprometimento da qualidade do solo, sobretudo pela suscetibilidade aos processos de compactação, de salinização e de sodificação, em relação aos outros usos sem irrigação. Por outro lado, os solos irrigados se destacaram pela suscetibilidade às melhorias na fertilidade e na acidificação. Na verdade, os efeitos negativos, assim como melhorias na qualidade do solo, também foram notados nos solos com outros usos sem irrigação, porém de modo menos acentuado. Em geral, as terras do Perímetro de Mirorós possuem potencialidades para a agricultura geral ou para a agricultura irrigada, mas há urgência, especialmente, em intervenções no manejo, com necessidades de Conservação ou Conservação Prioritária. Além disso, há exigências de intervenções no uso, implicando na Recuperação/Preservação Prioritária de áreas que estejam sendo utilizadas acima do seu potencial, como também de intervenções no uso e manejo, ou seja, na Recuperação Prioritária. Os métodos propostos podem ser considerados ferramentas essenciais para a conservação dos recursos naturais na área de estudo e contribuir para o alcance da sustentabilidade no meio agrícola.

Composants de systèmes de sûreté nucléaire sont en général très fiable, ce qui conduit à une difficulté de modéliser leurs comportements de dégradation et d'échec en raison de la quantité limitée de données disponibles. Par ailleurs, la complexité de cette tâche de modélisation est augmentée par le fait que ces systèmes sont souvent l'objet de multiples processus concurrents de dégradation et que ceux-ci peut être dépendants dans certaines circonstances, et influencé par un certain nombre de facteurs externes (par exemple la température, le stress, les chocs mécaniques, etc.).Dans ce cadre de problème compliqué, ce travail de thèse vise à développer un cadre holistique de modèles et de méthodes de calcul pour l'analyse basée sur la fiabilité et la maintenance d'optimisation des systèmes de sûreté nucléaire en tenant compte des connaissances disponibles sur les systèmes, les comportements de dégradation et de défaillance, de leurs dépendances, les facteurs influençant externes et les incertitudes associées.Les contributions scientifiques originales dans la thèse sont:(1) Pour les composants simples, nous intégrons des chocs aléatoires dans les modèles de physique multi-états pour l'analyse de la fiabilité des composants qui envisagent dépendances générales entre la dégradation et de deux types de chocs aléatoires.(2) Pour les systèmes multi-composants (avec un nombre limité de composants):(a) un cadre de modélisation de processus de Markov déterministes par morceaux est développé pour traiter la dépendance de dégradation dans un système dont les processus de dégradation sont modélisées par des modèles basés sur la physique et des modèles multi-états; (b) l'incertitude épistémique à cause de la connaissance incomplète ou imprécise est considéré et une méthode volumes finis est prolongée pour évaluer la fiabilité (floue) du système; (c) les mesures d'importance de l'écart moyen absolu sont étendues pour les composants avec multiples processus concurrents dépendants de dégradation et soumis à l'entretien; (d) la politique optimale de maintenance compte tenu de l'incertitude épistémique et la dépendance de dégradation est dérivé en combinant schéma volumes finis, évolution différentielle et non-dominée de tri évolution différentielle; (e) le cadre de la modélisation de (a) est étendu en incluant les impacts des chocs aléatoires sur les processus dépendants de dégradation.(3) Pour les systèmes multi-composants (avec un grand nombre de composants), une méthode d'évaluation de la fiabilité est proposé considérant la dépendance dégradation en combinant des diagrammes de décision binaires et simulation de Monte Carlo pour réduire le coût de calcul. / Components of nuclear safety systems are in general highly reliable, which leads to a difficulty in modeling their degradation and failure behaviors due to the limited amount of data available. Besides, the complexity of such modeling task is increased by the fact that these systems are often subject to multiple competing degradation processes and that these can be dependent under certain circumstances, and influenced by a number of external factors (e.g. temperature, stress, mechanical shocks, etc.). In this complicated problem setting, this PhD work aims to develop a holistic framework of models and computational methods for the reliability-based analysis and maintenance optimization of nuclear safety systems taking into account the available knowledge on the systems, degradation and failure behaviors, their dependencies, the external influencing factors and the associated uncertainties.The original scientific contributions of the work are: (1) For single components, we integrate random shocks into multi-state physics models for component reliability analysis, considering general dependencies between the degradation and two types of random shocks. (2) For multi-component systems (with a limited number of components):(a) a piecewise-deterministic Markov process modeling framework is developed to treat degradation dependency in a system whose degradation processes are modeled by physics-based models and multi-state models; (b) epistemic uncertainty due to incomplete or imprecise knowledge is considered and a finite-volume scheme is extended to assess the (fuzzy) system reliability; (c) the mean absolute deviation importance measures are extended for components with multiple dependent competing degradation processes and subject to maintenance; (d) the optimal maintenance policy considering epistemic uncertainty and degradation dependency is derived by combining finite-volume scheme, differential evolution and non-dominated sorting differential evolution; (e) the modeling framework of (a) is extended by including the impacts of random shocks on the dependent degradation processes.(3) For multi-component systems (with a large number of components), a reliability assessment method is proposed considering degradation dependency, by combining binary decision diagrams and Monte Carlo simulation to reduce computational costs.

Nano-particle aerosols are one of the major types of air pollutants in the urban indoor and outdoor environments. Therefore, determination of mechanisms of formation, dispersion, evolution, and transformation of combustion aerosols near the major source of this type of air pollution - busy roads and road networks - is one of the most essential and urgent goals. This Thesis addresses this particular direction of research by filling in gaps in the existing physical understanding of aerosol behaviour and evolution. The applicability of the Gaussian plume model to combustion aerosols near busy roads is discussed and used for the numerical analysis of aerosol dispersion. New methods of determination of emission factors from the average fleet on a road and from different types of vehicles are developed. Strong and fast evolution processes in combustion aerosols near busy roads are discovered experimentally, interpreted, modelled, and statistically analysed. A new major mechanism of aerosol evolution based on the intensive thermal fragmentation of nano-particles is proposed, discussed and modelled. A comprehensive interpretation of mutual transformations of particle modes, a strong maximum of the total number concentration at an optimal distance from the road, increase of the proportion of small nano-particles far from the road is suggested. Modelling of the new mechanism is developed on the basis of the theory of turbulent diffusion, kinetic equations, and theory of stochastic evaporation/degradation processes. Several new powerful statistical methods of analysis are developed for comprehensive data analysis in the presence of strong turbulent mixing and stochastic fluctuations of environmental factors and parameters. These methods are based upon the moving average approach, multi-variate and canonical correlation analyses. As a result, an important new physical insight into the relationships/interactions between particle modes, atmospheric parameters and traffic conditions is presented. In particular, a new definition of particle modes as groups of particles with similar diameters, characterised by strong mutual correlations, is introduced. Likely sources of different particle modes near a busy road are identified and investigated. Strong anti-correlations between some of the particle modes are discovered and interpreted using the derived fragmentation theorem. The results obtained in this thesis will be important for accurate prediction of aerosol pollution levels in the outdoor and indoor environments, for the reliable determination of human exposure and impact of transport emissions on the environment on local and possibly global scales. This work will also be important for the development of reliable and scientifically-based national and international standards for nano-particle emissions.