The objective of this thesis is to develop a nondestructive evaluation method that could accurately locate and size damage in structures. The method is to be based on pre-damage and post-damage strain energies of beam and column elements. The method should apply to 1-D as well as 2-D and 3-D structures with single or multiple damage locations. To achieve the objectives listed above, the following four tasks are addressed: (1) the development of the theoretical foundations of the nondestructive evaluation theory; (2) the validation of the accuracy of the theory using exact structural deformational data generated from the static analysis of F. E. models in SAP2000; (3) the validation of the practical feasibility of the theory using approximated structural deformational data generated from the modal analyses of F.E. models in SAP2000; and (4) the application of the methodology to an existing structure. The numerical simulations of damage indicate that the proposed NDE method can clearly locate damage in the structures and provide an accurate quantitative value of damage severities, even when only a few lower frequencies and mode shapes are known. The field data analysis results indicate that the developed NDE method can locate damage and provide conservative values for damage severity estimations.

Modificações neurosensoriais, decorrentes de complicações relacionadas a tratamentos odontológicos, estão entre as principais causas de litígio envolvendo cirurgiões-dentistas. Um dos nervos mais acometidos nestes casos é o nervo lingual. Entre os inconvenientes apontados nas queixas judiciais estão as dificuldades na articulação dos sons da fala nessas situações. Neste contexto, o objetivo desse estudo foi verificar se há dano à função fonética resultante da ausência de sensibilidade unilateral da língua induzida por anestesia do nervo lingual. Participaram do estudo 10 sujeitos voluntários, brasileiros, do sexo masculino, com idade entre 21 e 27 anos. Foram realizadas as análises perceptual e acústica das falas gravadas antes e depois da anestesia do nervo lingual. Além disso, os sujeitos da pesquisa responderam a um questionário com o objetivo de avaliar o nível de desconforto e dificuldade na produção da fala. Após assinatura do TCLE e avaliação clínica e fonoaudiológica, os sujeitos foram divididos em dois grupos. As gravações consistiram em conjuntos de vogais e palavras. Para o segundo grupo, a leitura de um texto foi acrescentada para o estudo da fala encadeada. Para a análise perceptual foram observados os comportamentos das falas em relação à inteligibilidade, ao pitch, loudness e co-articulação. Para o segundo grupo, a fala encadeada foi analisada quanto ao ritmo, fluidez, co-articulação e velocidade de produção. Não foram observadas quaisquer diferenças nos parâmetros perceptivo auditivos definidos para o estudo. Para a análise acústica, realizou-se o estudo de cinco vogais isoladas e da fricativa sibilante /s/. Foram extraídos e comparados os valores dos dois primeiros formantes das vogais /a, / , /i/, / e /u/. Foi possível observar que, apesar de existirem diferenças nos valores absolutos dos formantes, eles se mantiveram em faixas de freqüências características das vogais faladas nos dois momentos e, além disso, nenhum indivíduo relatou qualquer dificuldade em relação à produção das vogais. Os parâmetros escolhidos para análise comparativa da consoante sibilante /s/ foram: a localização do pico espectral de maior amplitude, o coeficiente de assimetria, o coeficiente de curtose e o centro de gravidade. As análises demonstraram que os padrões desses parâmetros também foram mantidos após a aplicação da anestesia. Ademais, não foram encontradas diferenças estatisticamente significantes entre os dois momentos, para os parâmetros analisados. Apesar de 03 sujeitos (30%) relatarem dificuldades na produção de determinados fonemas, as análises das gravações de suas falas demonstraram não haver nenhuma diferença significativa entre os dois momentos. O presente trabalho ofereceu informações importantes a respeito de técnicas que podem ser utilizadas nas perícias envolvendo o dano fonético. Ficando claro que é preciso uma interpretação criteriosa dos resultados apresentados, especialmente nas análises acústicas. Os resultados encontrados permitem concluir que não houve dano fonético resultante da inibição funcional unilateral do nervo lingual para o grupo pesquisado. / Sensorineural changes due to complications related to dentistry treatments are between the main litigation causes involving dentists. One of the most affected nerves in these situations is the lingual nerve. Speech changes are related as a complication in these cases. The purpose of this study was to analyze the possible phonetic damage resulting from lingual nerve sensorial alterations induced by anesthesia. The study group consisted of 10 men, aged between 21 and 27 years. Perceptual and acoustic analyses of the speech samples recorded before and after the lingual nerve anesthesia were performed. Moreover, the subjects answered a questionnaire to discuss the level of discomfort and difficulty in speaking. The informers were divided into two groups. The recording consisted of a combination of vowels and words. A text reading was added for the second group. Perceptual analyses studied the behavior of the intelligibility, pitch, loudness and co-articulation. For the second group, the pace, fluidity, co-articulation and production speed were evaluated. There were no differences in perceptive parameters defined for the study. The acoustic analyses of isolated vowels /a/, / , /i/, / , /u/ were performed. The first two formant frequencies values were analyzed. It was possible to observe that, despite of the differences in absolute values of formants, they were located in bands of frequencies that are characteristics of the vowels spoken, in both moments. In addition, none of the subjects reported any difficulty in produce vowel sounds. The parameters chosen for acoustic analysis of /s/ sound were: location of the greater spectral peak, skewness, kurtosis and center of gravity. The analyses showed that the patterns of these parameters were maintained after the application of the anesthesia. Moreover, when the two moments were compared, no statistically significant differences for the parameters analyzed were found. Three subjects (30%) reported difficulties in the production of certain phonemes, but the analysis of their records did not show any significant difference between the two moments. This study provides important information about techniques that can be used in phonetic damage investigation. A careful interpretation of the results presented by acoustic analyses in these cases is necessary. It can be concluded that there was no phonetic damage resulting from the unilateral inhibition of the lingual nerve function for the enrolled group.

Modificações neurosensoriais, decorrentes de complicações relacionadas a tratamentos odontológicos, estão entre as principais causas de litígio envolvendo cirurgiões-dentistas. Um dos nervos mais acometidos nestes casos é o nervo lingual. Entre os inconvenientes apontados nas queixas judiciais estão as dificuldades na articulação dos sons da fala nessas situações. Neste contexto, o objetivo desse estudo foi verificar se há dano à função fonética resultante da ausência de sensibilidade unilateral da língua induzida por anestesia do nervo lingual. Participaram do estudo 10 sujeitos voluntários, brasileiros, do sexo masculino, com idade entre 21 e 27 anos. Foram realizadas as análises perceptual e acústica das falas gravadas antes e depois da anestesia do nervo lingual. Além disso, os sujeitos da pesquisa responderam a um questionário com o objetivo de avaliar o nível de desconforto e dificuldade na produção da fala. Após assinatura do TCLE e avaliação clínica e fonoaudiológica, os sujeitos foram divididos em dois grupos. As gravações consistiram em conjuntos de vogais e palavras. Para o segundo grupo, a leitura de um texto foi acrescentada para o estudo da fala encadeada. Para a análise perceptual foram observados os comportamentos das falas em relação à inteligibilidade, ao pitch, loudness e co-articulação. Para o segundo grupo, a fala encadeada foi analisada quanto ao ritmo, fluidez, co-articulação e velocidade de produção. Não foram observadas quaisquer diferenças nos parâmetros perceptivo auditivos definidos para o estudo. Para a análise acústica, realizou-se o estudo de cinco vogais isoladas e da fricativa sibilante /s/. Foram extraídos e comparados os valores dos dois primeiros formantes das vogais /a, / , /i/, / e /u/. Foi possível observar que, apesar de existirem diferenças nos valores absolutos dos formantes, eles se mantiveram em faixas de freqüências características das vogais faladas nos dois momentos e, além disso, nenhum indivíduo relatou qualquer dificuldade em relação à produção das vogais. Os parâmetros escolhidos para análise comparativa da consoante sibilante /s/ foram: a localização do pico espectral de maior amplitude, o coeficiente de assimetria, o coeficiente de curtose e o centro de gravidade. As análises demonstraram que os padrões desses parâmetros também foram mantidos após a aplicação da anestesia. Ademais, não foram encontradas diferenças estatisticamente significantes entre os dois momentos, para os parâmetros analisados. Apesar de 03 sujeitos (30%) relatarem dificuldades na produção de determinados fonemas, as análises das gravações de suas falas demonstraram não haver nenhuma diferença significativa entre os dois momentos. O presente trabalho ofereceu informações importantes a respeito de técnicas que podem ser utilizadas nas perícias envolvendo o dano fonético. Ficando claro que é preciso uma interpretação criteriosa dos resultados apresentados, especialmente nas análises acústicas. Os resultados encontrados permitem concluir que não houve dano fonético resultante da inibição funcional unilateral do nervo lingual para o grupo pesquisado. / Sensorineural changes due to complications related to dentistry treatments are between the main litigation causes involving dentists. One of the most affected nerves in these situations is the lingual nerve. Speech changes are related as a complication in these cases. The purpose of this study was to analyze the possible phonetic damage resulting from lingual nerve sensorial alterations induced by anesthesia. The study group consisted of 10 men, aged between 21 and 27 years. Perceptual and acoustic analyses of the speech samples recorded before and after the lingual nerve anesthesia were performed. Moreover, the subjects answered a questionnaire to discuss the level of discomfort and difficulty in speaking. The informers were divided into two groups. The recording consisted of a combination of vowels and words. A text reading was added for the second group. Perceptual analyses studied the behavior of the intelligibility, pitch, loudness and co-articulation. For the second group, the pace, fluidity, co-articulation and production speed were evaluated. There were no differences in perceptive parameters defined for the study. The acoustic analyses of isolated vowels /a/, / , /i/, / , /u/ were performed. The first two formant frequencies values were analyzed. It was possible to observe that, despite of the differences in absolute values of formants, they were located in bands of frequencies that are characteristics of the vowels spoken, in both moments. In addition, none of the subjects reported any difficulty in produce vowel sounds. The parameters chosen for acoustic analysis of /s/ sound were: location of the greater spectral peak, skewness, kurtosis and center of gravity. The analyses showed that the patterns of these parameters were maintained after the application of the anesthesia. Moreover, when the two moments were compared, no statistically significant differences for the parameters analyzed were found. Three subjects (30%) reported difficulties in the production of certain phonemes, but the analysis of their records did not show any significant difference between the two moments. This study provides important information about techniques that can be used in phonetic damage investigation. A careful interpretation of the results presented by acoustic analyses in these cases is necessary. It can be concluded that there was no phonetic damage resulting from the unilateral inhibition of the lingual nerve function for the enrolled group.

The objective of this study is to model material removal with cutting tool in the case of the machining of Titanium alloy (Ti-6Al-4V) and to bring a multi-physic comprehension of chip formation and the tool/workpiece interaction by adopting finite element approaches and methodologies. For that, the present contribution begins by a macroscopic modeling of the orthogonal cutting process. The cut material behavior considered is supposed based on JC law. Moreover, in order to simulate properly the chip genesis, the material fracture energy concept is adopted for controlling the material damage evolution. This allows capturing the shear strain localization and consequently the chip segmentation for a given set of cutting parameters. The frictional contact model considers the influence of temperature on the limiting shear stress at the tool/chip interface. As a result, this reliable model has the capability to simulate the cutting process even with high coefficient of friction and with large cutting edge radius. The parametric study carried out by referring to this model shows a very interesting corroboration with experimental results. In a second step, the present research work presents a material microstructure-level cutting model (MML cutting model) for cutting simulation. The crystal plasticity theory is adopted for modeling the cutting of the Titanium alloy Ti-6Al-4V in orthogonal case. In this model, the grains of the studied material are explicitly considered, and their orientation angles and slip system strength anisotropy are considered as the main source of the microstructure heterogeneity in the cutting material. To simulate the material degradation process, the continuum intra-granular damage and discrete cohesive zone inter-granular damage models are developed, wherein the zero thickness cohesive elements are implemented to simulate the bond between grain interfaces. The material model is validated by a comparison of compression tests from literature. Finally, simulation results demonstrate the possibility to capture the influence of the microstructure on the material removal in terms of chip formation. It is demonstrated that the grain orientation angle plays an important role for the chip segmentation and its periodicity during the cutting process. This certainly can affect the evolution of the cutting force. Additionally, the surface integrity is discussed based on the MML cutting model for different cutting speeds and feed rates. Indeed, a parametric study shows that the surface integrity is seriously affected by the machining parameters, and the affected region is limited within three layer grains for the present MML cutting model.

Master of Science / Department of Civil Engineering / Hayder A. Rasheed / The structural deterioration of aging infrastructure systems is becoming an increasingly important issue worldwide. To compound the issue, economic strains limit the resources available for repair or replacement of such systems. Over the past several decades, structural health monitoring (SHM) has proved to be a cost-effective method for detection and evaluation of damage in structures. Visual inspection and condition rating is one of the most commonly applied SHM techniques, but the effectiveness of this method suffers due to its reliance on the availability and experience of qualified personnel performing largely qualitative damage evaluations. The artificial neural network (ANN) approach presented in this study attempts to augment visual inspection methods by developing a crack-induced damage quantification model for reinforced concrete bridge girders that requires only the results of limited field measurements to operate. Simply-supported three-dimensional reinforced concrete T-beams with varying geometric, material, and cracking properties were modeled using Abaqus finite element (FE) analysis software. Up to five cracks were considered in each beam, and the ratios of stiffness between cracked and healthy beams with the same geometric and material parameters were measured at nine equidistant nodes along the beam. Two feedforward ANNs utilizing backpropagation learning algorithms were then trained on the FE model database with beam properties serving as inputs for both neural networks. The outputs for the first network consisted of the nodal stiffness ratios, and the sole output for the second ANN was a health index parameter, computed by normalizing the area under the stiffness ratio profile over the span length of the beam. The ANNs achieved excellent prediction accuracies with coefficients of determination (R²) exceeding 0.99 for both networks. Additional FE models were created to further assess the networks’ prediction capabilities on data not utilized in the training process. The ANNs displayed good prediction accuracies (R² > 0.8) even when predicting damage levels in beams with geometric, material, and cracking parameters dissimilar from those found in the training database. A touch-enabled user interface was developed to allow the ANN models to be utilized for on-site damage evaluations. The results of this study indicate that application of ANNs with FE modeling shows great promise in SHM for damage evaluation.

Submitted by (edna.saturno@ufrpe.br) on 2016-11-24T16:49:55Z No. of bitstreams: 1 Jose Wagner da Silva Melo.pdf: 723569 bytes, checksum: 2dc5e4f230cd491babe7d343568a8d62 (MD5) / Made available in DSpace on 2016-11-24T16:49:55Z (GMT). No. of bitstreams: 1 Jose Wagner da Silva Melo.pdf: 723569 bytes, checksum: 2dc5e4f230cd491babe7d343568a8d62 (MD5) Previous issue date: 2010-06-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Aceria guerreronis Keifer (Acari: Eriophyidae) is widespread in most coconut growing regions of the Americas and Africa and it has been established rapidly in some major producing countries in Asia. It is considered a major coconut pest in the world. Several studies have being carried out to obtain information to control this pest. This study aimed to: (I) investigate the damage intensity of A. guerreronis on coconut fruits in the field under different conditions: (i) plants with removed bunches; (ii) bunches with the distal portion of the spikelets removed; (iii) bunches monthly sprayed with Abamectina (9g/ha); (iv) and control plants; and (II) studing the foraging behavior of the predatory mites Neoseiulus baraki (Athias-Henriot) and Proctolaelaps bickley Bram, evaluating the ability of the predators to identify and differentiate odors from parts of coconut plants infested or not by the eriophyid using Y-tube olfactometer and “T” arenas. The removal of spikelet had no effect the damage level of new bunches emitted bythe plant, but delayed the damage intensity of A. guerreronis in about 1 month. After the removal of all bunches, the intensity of damage was restored in two months to the new bunches emitted. Chemical control with Abamectin, on monthly based application, kept the A. guerreronis intensity of damage at low levels. In olfactometer tests both predators were able to distinguish between the infested plant parts and the air stream. The predators preferred infested parts over their respectivenon-infested ones, and among the infested plant parts, the spikelets promoted greater attraction to predators. In arena tests both predators preferred epidermis’s disc of coconut fruits infested with A. guerreronis over other sources. The results showed that both predators are able locating A. guerreronis by olfactory stimuli. / Aceria guerreronis Keifer (Acari: Eriophyidae) está disseminado nas principais áreas de produção de coco nas Américas e África e tem se estabelecido rapidamente em alguns dos principais países produtores da Ásia. É considerada uma das principais pragas do coqueiro no mundo. Atualmente, vários estudos estão sendo conduzidos para a obtenção de informações necessárias para auxiliar no controle dessa praga. Os objetivos deste trabalho foram: (I) investigar a intensidade de dano de A. guerreronis em frutos de coqueiro no campo sob diferentes condições: (i) plantas com cachos removidos; (ii) cachos com a porção distal das espiguetas removidas; (iii) cachos pulverizados mensalmente com Abamectina (9g/ha); (iv) plantas sem alterações nos cachos; e (II) estudar o comportamento de forrageamento dos ácaros predadores Neoseiulusbaraki (Athias-Henriot) e Proctolaelaps bickleyi Bram (Acari: Phytoseiidae, Ascidae), avaliando a capacidade desses predadores de identificar e diferenciar odores provenientes de diferentes partes de plantas de coqueiro infestadas ou não pelo eriofídeo em olfatômetro do tipo “Y” e em arenas do tipo “T”. Os resultados demonstraram que a retirada da porção distal da espigueta não apresentou efeito sobre a intensidade de dano de A. guerreronis nos novos cachos emitidos, no entanto a retardou em aproximadamente 1 mês. Após a retirada de todos os cachos da planta aintensidade de dano foi restabelecida em dois meses para os cachos novos emitidos. O controle químico com Abamectina, em aplicações mensais, proporcionou a manutenção dos danos de A. guerreronis em baixos níveis de intensidade. Os predadores mostraram-se capazes de distinguir entre partes de plantas infestadas por A. guerreronis e a corrente de ar. Os predadores também preferiram as partes infestadas das plantas a suas respectivas partes não infestadas, e dentre as partes da planta infestada, as espiguetas propiciaram maior atração aos predadores. Nos testes em arena tipo “T”, ambos predadores preferiram discos de epiderme de frutos de coqueiro infestados com A. guerreronis às outras fontes. Os resultados demonstram que ambos predadores são capazes de localizar A. guerreronis através de estímulos olfativos.

Diversos estudos realizados nas últimas duas décadas sugerem que plantios florestais comerciais têm sido apontados como catalisadores da regeneração natural em seu sub-bosque, contribuindo para a conservação da biodiversidade. Com a finalidade de obter uma visão multifacetada sobre as condições da regeneração natural efetuou-se o estudo sobre a sua composição formada em um antigo talhão de Eucalyptus citriodora Hook com mais de 60 anos e quais os impactos imediatos ocasionados nesse sub-bosque com a retirada de alguns indivíduos de eucalipto. O estudo foi realizado em 10.000 m², aplicando o censo das árvores de eucalipto. Para o levantamento da regeneração natural, foram amostradas 20 parcelas de 10 x 10 m, com área amostral de 2.000 m². Os indivíduos foram identificados e medidos a partir do DAP (diâmetro na altura de 1,30 m do solo) em 3 classes de diâmetro: Classe 1: Indivíduos com DAP 5,0 cm, Classe 2: Indivíduos 1 cm < 5,0 cm e Classe 3: Contagem dos indivíduos > 0,50 cm de altura. O reconhecimento do subbosque foi necessário para serem compilados com literaturas semelhantes e considerando a deficiência de estudos sobre danos causados na regeneração natural e na dinâmica do dossel sob plantios florestais comerciais, os objetivos deste trabalho foram: identificar, qualificar e quantificar os danos imediatos causados pela exploração florestal sobre a estrutura da regeneração no momento da derrubada dos eucaliptos, com a finalidade de gerar informações básicas a respeito da determinação de impactos imediatos e a diferenciação do índice de área foliar (IAF) ocorrido nas clareiras formadas. A estimativa foi realizada através do Índice de Área Foliar Real (m² folha m-2 solo) coletados com o aparelho LAI-2000 antes e depois da derrubada. Para a medição dos impactos, foi calculada a quantidade de área basal e volume que foram explorados. As análises mostraram que os danos causados não possuíram relação direta com a quantidade de área basal retirada e sim em relação ao volume. Quanto à variação do IAF as análises estatísticas mostraram que as mudanças de valores pela perda de dossel foram significativas após a derrubada. / Researchers conducted over the past two decades suggest that commercial forest plantations have been singled out as catalysts of natural regeneration in their understory, contributing to biodiversity conservation. With the purpose of obtaining a multi-faceted vision about the conditions of natural regeneration, study on its composition formed in an ancient plot of Eucalyptus citriodora Hook with more than 60 years and which the immediate impacts caused in the understory with the withdrawal of some individuals of eucalyptus. The study was conducted in 10,000 square meters, where the census was conducted of eucalyptus trees. For the survey of natural regeneration, we sampled 20 plots os 10 x 10m, with sampling area of 2000 m². The individuals were identified and measured from the DBH (diameter at height of 1.30 m above the ground) in 3 diameter classes: Class 1: Individuals with DBH 5.0 cm; Class 2: Individuals 1 cm and 5.0 cm; and Class 3: count of 0.50 cm tall individuals. The recognition of the understory was required to be compiled with similar literatures and considering the lack of studies on damage caused in natural regeneration and the dynamic in canopy of commercial forest plantations, the goals of this work were: identify, qualify and quantify the immediate damage caused by forestry exploitation on the structure of the regeneration at the time of the eucalyptus felling, with the purpose of generate basic information about the immediate impact determination and the distinction of leaf area index (LAI) occurred in clearings formed. The estimate was accomplished through the Actual Leaf Area index (m2 of leaf per m2 of soil) collected with LAI-2000 before and after the removal of the trees. For measure the impacts, was calculated the amount of basal area and volume that were explored, ranging between treatments in 0.13 m² and 3.37 m³. The analyses showed that the damage caused had no direct relation with the amount of basal area withdrawal and had direct relation to the volume. About the IAF variation, the statistical analyses showed that the values change for the loss of canopy were significant after the removal of the trees.

La durabilité et la fiabilité sont deux facteurs clés dont la maîtrise est essentielle en vue de l’utilisation des composites à matrice céramique (CMC) pour des applications aéronautiques. Il est nécessaire pour cela de pouvoir estimer la durée de vie des structures en service. Cela requiert de quantifier l’endommagement mais aussi d’identifier les différents mécanismes qui en sont à l’origine. Il est donc indispensable d’une part de caractériser les matériaux et de définir les indicateurs d’endommagement les plus adaptés. D’autre part, l’utilisation ou le développement de modèles doivent permettre l’estimation de la durée de vie restante à partir de l’analyse des événements précurseurs associés à la croissance de l’endommagement. L’Emission Acoustique (EA) est une technique qui permet de répondre à cette problématique. En effet, les mécanismes d’endommagement s’accompagnent de libération d’énergie sous forme d’ondes élastiques transitoires. Leur détection, communément appelée émission acoustique, permet de suivre en temps réel le développement de l’endommagement du matériau. Ce moyen est mis en œuvre dans cette thèse qui comporte deux volets complémentaires. Le premier volet porte sur l’identification de la signature acoustique des différents mécanismes impliqués dans l’endommagement des composites à matrice céramique, en vue de permettre une caractérisation fine de la croissance de l’endommagement et de fournir des indicateurs pour la prévision de la rupture. Le second volet porte sur l’estimation de la durée de vie restante sous sollicitation de fatigue statique, à partir de l’émission acoustique en utilisant l’énergie des sources d’EA comme mesure de l’endommagement. Les travaux réalisés dans cette thèse montrent l’apport de l’EA pour l’analyse du comportement mécanique et la prévision de la durée de vie des CMC. Dans le premier volet, la caractérisation robuste des sources d’EA rend possible le suivi en temps réel de l’apparition de chaque mécanisme d’endommagement grâce à une analyse multivariable. Dans le second volet, deux indicateurs, calculables en temps réel, permettent d’identifier deux phases reproductibles dans le comportement des CMC sollicités en fatigue statique, à partir de la libération d’énergie des sources d’EA. La prévision en temps réel de la durée de vie restante est envisageable grâce à la détection de la seconde phase et à la modélisation, par une loi de type puissance, de la libération d’énergie associée. / Ceramic matrix composites (CMCs) are candidates for use in aeronautical applications for which durability and reliability are key factors. Beyond damage characterization, the current objective is to predict structures lifetime in service conditions. This requires quantifying damage evolution and identifying the various damage mechanisms that are involved. Therefore, it is necessary to characterize materials and define suitable damage indicators. The use or development of models would then allow the evaluation of remaining lifetime based on the analysis of precursory events. In this context, Acoustic Emission (AE) is a suitable technique. Indeed, damage mechanisms release energy in the form of transient elastic waves. Their recording, named Acoustic Emission, allows monitoring material damage growth. This technique is used in this work, which is composed of two complementary parts. The first part aims at identifying the acoustic signature of mechanisms involved in damaging of ceramic matrix composites. This would allow an accurate characterization of damage evolution and would provide indicators for rupture prediction. The second part focuses on the evaluation of remaining lifetime under static fatigue loading based on the energy of AE sources as a measure of damage. The following work shows the contribution of acoustic emission for the analysis of mechanical behaviour and lifetime prediction of CMCs. In the first part, a robust characterization of AE sources and the use of multivariate analysis allow monitoring the growth of each damage mechanism. In the second part, two reproducible phases in the behaviour of CMCs under static fatigue are identified on the AE sources energy release by two real-time indicators. The detection of the second phase and modelling of associated energy release by a power law would allow real-time prediction of the remaining lifetime.

Diversos estudos realizados nas últimas duas décadas sugerem que plantios florestais comerciais têm sido apontados como catalisadores da regeneração natural em seu sub-bosque, contribuindo para a conservação da biodiversidade. Com a finalidade de obter uma visão multifacetada sobre as condições da regeneração natural efetuou-se o estudo sobre a sua composição formada em um antigo talhão de Eucalyptus citriodora Hook com mais de 60 anos e quais os impactos imediatos ocasionados nesse sub-bosque com a retirada de alguns indivíduos de eucalipto. O estudo foi realizado em 10.000 m², aplicando o censo das árvores de eucalipto. Para o levantamento da regeneração natural, foram amostradas 20 parcelas de 10 x 10 m, com área amostral de 2.000 m². Os indivíduos foram identificados e medidos a partir do DAP (diâmetro na altura de 1,30 m do solo) em 3 classes de diâmetro: Classe 1: Indivíduos com DAP 5,0 cm, Classe 2: Indivíduos 1 cm < 5,0 cm e Classe 3: Contagem dos indivíduos > 0,50 cm de altura. O reconhecimento do subbosque foi necessário para serem compilados com literaturas semelhantes e considerando a deficiência de estudos sobre danos causados na regeneração natural e na dinâmica do dossel sob plantios florestais comerciais, os objetivos deste trabalho foram: identificar, qualificar e quantificar os danos imediatos causados pela exploração florestal sobre a estrutura da regeneração no momento da derrubada dos eucaliptos, com a finalidade de gerar informações básicas a respeito da determinação de impactos imediatos e a diferenciação do índice de área foliar (IAF) ocorrido nas clareiras formadas. A estimativa foi realizada através do Índice de Área Foliar Real (m² folha m-2 solo) coletados com o aparelho LAI-2000 antes e depois da derrubada. Para a medição dos impactos, foi calculada a quantidade de área basal e volume que foram explorados. As análises mostraram que os danos causados não possuíram relação direta com a quantidade de área basal retirada e sim em relação ao volume. Quanto à variação do IAF as análises estatísticas mostraram que as mudanças de valores pela perda de dossel foram significativas após a derrubada. / Researchers conducted over the past two decades suggest that commercial forest plantations have been singled out as catalysts of natural regeneration in their understory, contributing to biodiversity conservation. With the purpose of obtaining a multi-faceted vision about the conditions of natural regeneration, study on its composition formed in an ancient plot of Eucalyptus citriodora Hook with more than 60 years and which the immediate impacts caused in the understory with the withdrawal of some individuals of eucalyptus. The study was conducted in 10,000 square meters, where the census was conducted of eucalyptus trees. For the survey of natural regeneration, we sampled 20 plots os 10 x 10m, with sampling area of 2000 m². The individuals were identified and measured from the DBH (diameter at height of 1.30 m above the ground) in 3 diameter classes: Class 1: Individuals with DBH 5.0 cm; Class 2: Individuals 1 cm and 5.0 cm; and Class 3: count of 0.50 cm tall individuals. The recognition of the understory was required to be compiled with similar literatures and considering the lack of studies on damage caused in natural regeneration and the dynamic in canopy of commercial forest plantations, the goals of this work were: identify, qualify and quantify the immediate damage caused by forestry exploitation on the structure of the regeneration at the time of the eucalyptus felling, with the purpose of generate basic information about the immediate impact determination and the distinction of leaf area index (LAI) occurred in clearings formed. The estimate was accomplished through the Actual Leaf Area index (m2 of leaf per m2 of soil) collected with LAI-2000 before and after the removal of the trees. For measure the impacts, was calculated the amount of basal area and volume that were explored, ranging between treatments in 0.13 m² and 3.37 m³. The analyses showed that the damage caused had no direct relation with the amount of basal area withdrawal and had direct relation to the volume. About the IAF variation, the statistical analyses showed that the values change for the loss of canopy were significant after the removal of the trees.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19299号 / 工博第4096号 / 新制||工||1631(附属図書館) / 32301 / 京都大学大学院工学研究科建築学専攻 / (主査)教授 中島 正愛, 教授 川瀬 博, 教授 竹脇 出 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM