Made available in DSpace on 2014-06-11T19:22:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-02-03Bitstream added on 2014-06-13T20:48:35Z : No. of bitstreams: 1 furtado_mb_me_botfca.pdf: 393078 bytes, checksum: def48bccd2c07da6fc33ce1966be2848 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A cultura do milho constitui um dos principais insumos para o segmento produtivo, porém, a sua produtividade é considerada baixa devido a inúmeros fatores que ainda precisam ser estudados, dentro os quais pode-se citar materiais genéticos adequados a cada região, densidade de semeadura, manejo do solo, dentre outros. Assim, com o objetivo de avaliar o desempenho de cultivares de milho com composições genéticas distintas, cultivadas em espaçamento reduzido, com variação no número de plantas por unidade de área, em sistemas de preparo de solo que variaram a intensidade e a profundidade de mobilização, realizou-se a presente pesquisa. O experimento foi desenvolvido na Fazenda Experimental Lageado da Faculdade de Ciências Agronômicas/UNESP-Campus de Botucatu, no ano agrícola de 2003/2004. O delineamento experimental utilizado foi o de parcela sub-subdividida, com 8x2x3 e quatro repetições, sendo os fatores de variações oito maneiras de preparo de solo, dois cultivares de milho e três populações de plantas. Os tratamentos com preparo de solo utilizados foram: T1- plantio direto em todas as safras; T2- arado de disco em todas as safras, trabalhando à profundidade de 0,20 a 0,25 m; T3- grade pesada em todas as safras, trabalhando à profundidade de 0,15 a 0,18 m; T4- escarificador em todas as safras, trabalhando à profundidade de 0,35 m; T5- arado de disco em duas safras sendo o escarificador na terceira safra, trabalhando à profundidade de 0,20 a 0,25 m; e T6- grade pesada em duas safras e arado de disco na terceira safra, T7- grade pesada em duas safras e escarificador na terceira safra, e T8- grade pesada na primeira safra, escarificador na segunda e arado de disco na terceira safra. O preparo secundário do solo foi feito com a passagem por duas vezes de grade niveladora trabalhando à profundidade de 0,10 a 0,13 m em todos os tratamentos, excetuando-se o plantio direto... / The corn crop is one of the mail materials to the productive segment. However, the productivity is considered low due to many different factors which need to be better studied, like genetic materials appropriated to each region, density sowing, soil tillage, among others. The objective of this study was the evaluation of the performance with corn cultivars a different genetic composition. These plants were planted in a reduced row width , with a variation in number of plants number by unit of area, in soil tillage systems that changed both the intensity and the deph of mobilization. The experiment was carried out in the Experimental Lageado Farm of the Agronomic Science College, UNESP-Botucatu-SP in 2003/2004. The experimental design used was the randomized blocks in split-splitplot, with 8x2x3 and four repetitions. The variation factors were 8 ways soil evaluation, two corn cultivars and three plant populations. The treatment with soil tillage used were:T1-no tillage in every harvest; T2-disc plowing in every harvest, working in depth of 0,20 to 0,25 m; T3- heavy harrowing in every harvest ,working in depth of 0,15 to 0,18 m; T4- chisel plow in every harvest, working in depth of 0,35 m; T5- disc plowing in twice harvest and chisel plow in the third, working in depth of 0,20 to 0,25 m; T6- heavy harrowing in twice harvest and disc plowing in the third; T7- heavy harrowing in twice harvest and chisel plow in the third, and T8- heavy harrowing in the first harvest, chisel plow in the second and disc plowing in the third, working in depth of 0,15 to 0,18 m. The secondary soil tillage was done passing the material twice by the level harrowing working in depth of 0, 10 to 0,13 m in every treatment, except the no tillage. The corn cultivars used were: The hybrid AG9010 and the variety AL34 and the populations were of 50000, 70000 and 100.000 plants.ha-1...(Complete abstract click electronic access below)

Com a crescente utilização de vigas mistas de aço e concreto em obras civis e devido à insuficiência de estudos relativos ao seu comportamento estrutural, investigações aprofundadas são necessárias para suprir as carências e aperfeiçoar o tema. Um fenômeno familiar na literatura de estruturas mistas é a distribuição não uniforme de tensões ao longo da largura da laje de concreto, denominado shear lag na literatura inglesa. Na análise e projeto de estruturas compostas, deflexões, tensões e resistência são tipicamente obtidas utilizando-se o conceito de largura efetiva, na qual o efeito shear lag é contabilizado indiretamente, substituindo a largura real da laje, por uma largura apropriadamente reduzida. Sem dispor de análises numéricas exatas para o dimensionamento prático, é necessário que códigos normativos forneçam métodos simplificados para a avaliação da largura efetiva minimizando perdas de precisão. Diante disso, no presente trabalho, procedimentos numéricos para a avaliação da largura efetiva, encontrados na literatura técnica, foram estudados e implementados ao modelo matemático em elementos finitos disponível no CEMACOM/PPGEC/UFRGS, capaz de representar com confiabilidade estruturas mistas. Comprovando-se a eficácia do modelo numérico em captar o efeito do shear lag, a resposta de uma viga mista biengastada, representando um vão intermediário de uma ponte contínua, submetida a um carregamento em longo prazo, e considerando-se os fenômenos reológicos do concreto de fluência e retração, além do comportamento não-linear devido a fissuração, é obtida e comparada à fórmulas estipuladas nas principais normas de projeto e em metodologias desenvolvidas por pesquisadores. Falhas potenciais nos códigos de projeto atuais foram evidenciadas, necessitando-se de adicionais estudos paramétricos experimentais e numéricos para a comprovação dos resultados. / With the increasing use of steel-concrete composite beams in bridges and buildings more investigations related to this topic are necessary to fill the needs and improve the subject. A familiar phenomenon in the literature of composite structures is the non-uniform distribution of stresses along the width of the concrete slab, called shear lag. In the analysis and design of composite beams, deflections, stresses, and strengths are typically obtained by utilizing the concept of effective width, in which shear lag effects are accounted for indirectly, by replacing the actual slab width by an appropriately reduced width. Without having exact numerical analysis for design, it is necessary that the design codes provide simplified methods for evaluating this effective width, minimizing losses of accuracy. In this work, numerical procedures for the evaluation of effective width, found in the specialized literature, were studied and implemented in the mathematical finite element model available in CEMACOM/PPGEC/UFRGS. This computational code is capable of representing the behavior of steel-concrete composite beams and is capable of capturing the shear lag effect. The response of a single span composite beam with fixed ends, representing an intermediate span of a continuous girder bridge, subject to long-term loading, and considering both rheological phenomena of concrete, such as creep and shrinkage, besides the non-linear behavior due to cracking, is obtained and compared to the stipulated formulas in the main code provisions and in the developed methodologies by some researchers. Potential failures in the current design codes were evidenced, requiring additional experimental and numerical parametric studies to prove the results.

Este estudo avaliou o posicionamento de caninos superiores permanentes em relação à largura do arco dentário superior e ao espaço na região anterior em pacientes na fase da dentadura mista. Foram analisados radiografias panorâmicas e modelos de estudo pré-tratamento de pacientes sem caninos deslocados (n = 68; 34 do gênero masculino; 34 do gênero feminino). A amostra foi dividida em idade e gênero. A largura do arco dentário e o espaço na região anterior entre os incisivos permanentes foram medidos. A posição e a inclinação do canino na radiografia panorâmica foram avaliadas em relação à linha mediana. Os resultados deste estudo mostram que não houve diferenças no posicionamento dos caninos permanentes em relação às variáveis analisadas. A média da angulação do canino superior em relação à linha mediana foi 6,2o e 10o para o gênero feminino e 9,2o e 11o para o masculino, respectivamente para o lado direito e esquerdo. / This study investigated the correlation between maxillary dental arch width, anterior space and the position of canines in patients during the mixed-dentition stage. Pretreatment Panoramic radiographs and dental casts were evaluated of randomly selected patients in the mixed dentition without maxillary canines displaced (n = 68; male, 34; female, 34). This sample was matched according to sex and age. Arch widths between the maxillary canines deciduous and anterior space between permanent incisors were measured and recorded. The position and inclination of canine on panoramic radiography was investigated. The results of this study showed that there are similarities in the position of the permanent canines in all cases and in both gender. The average of the canine\'s angulation to the mid-sagital plane was 6,2o and 10o for female and 9,2o and 11o for male, respectively to the right and left side.

Changes in the productivity of temperate forests have important implications for atmospheric carbon dioxide (CO2) concentrations, and many efforts have focused on methods to monitor both gross and net primary productivity in temperate forests. Remotely sensed vegetation indices provide spatially extensive measures of vegetation activity, and the Enhanced Vegetation Index (EVI) has been widely linked to photosynthetic activity of vegetation. Networks of tree ring width (TRW) chronologies provide ground-based estimates of annual net carbon (C) uptake in forests, and time series of EVI and TRW may capture common productivity signals. Robust correlations between mean TRW and EVI may enhance spatial extrapolations of TRW-based productivity estimates, ultimately improving understanding of spatio-temporal variability in forest productivity. The research presented in this thesis investigates potential empirical relationships between networks of TRW chronologies and time series of Landsat EVI and Landsat-based phenological metrics in the Northeast United States. We hypothesized that mean TRW is positively correlated with mean monthly EVI during the growing season, EVI integrated over the growing season, and growing season length. Results indicate that correlations between TRW and EVI are largely not significant in this region. The complex response of tree growth to a variety of limiting climatic factors in temperate forests may decouple measures of TRW growth and canopy reflectance. However, results also indicate that there may be important lag effects in which EVI affects mean TRW during the following year. These findings may improve understanding of links between C uptake and growth of tree stems over large spatial scales.

Sprinters are always looking for an improvement in their time, from the gun going off until the finish. An effective start can lead to reaching top velocity sooner and a decreased finish time. New developments in starting blocks, more specifically the width of the starting block pedal, has allowed for variation in foot placement in the blocks. With the ability to change how wide an athlete can place their feet in the blocks, this study looked at trying to find an optimum spacing for college level sprinters. Thirteen Male College Sprinters (mean age = 23.08 years) participated in this study. Subjects self selected their longitudinal block spacing with 3 different lateral positions being tested. In position 1, the feet were placed as narrow as was allowed by the starting block, simulating the width of a traditional set of blocks. Position 2 was defined by the hip width of the individual, distance between right ASIS to left ASIS. Position 3 was the preferred foot width of the subject as determined by completing a vertical jump. Measurements of peak force on the blocks at the time of the start as well as time to 10 m were taken. Neither peak force nor time to 10 m were different between conditions (p = .887, p = .135). The normal condition, position 1 (20cm), was measured to be the narrowest width with position 3 (mean = 37.6cm) being the widest in all subjects. The use of wider pedals on starting blocks is a fairly new idea in track and field, and is something that many athletes have not had the chance to practice with. Since the older style of starting blocks only allowed for a narrow stance that is what track athletes have become accustomed to and could possibly explain why there was no significant difference seen between the 3 starting positions. More research should be done after a time of adaptation to the new starting blocks by the athletes.

In recent years, the general interest in the safety of dams and reservoirs has grown appreciably. This research describes the application and design of labyrinth weirs to improve the performance of existing reservoirs and also to be used for the construction of new dams. The parameters that can affect the performance of labyrinth weirs are discussed. Tests were conducted on normal linear weirs with four different crest shapes to determine the rate of change of discharge coefficient when each type of weir is used. It is found that weirs with rounded-crest shape can pass more flow than other types of weirs when they are subjected to the same total operating head. Two design charts are developed for labyrinth weirs with rounded-crest shape with HT/P ratio ranges from 0.15 to 0.5 and 0.5 to 1.0. The areas of application of labyrinth weirs, design procedure, different cases of design, and a design example are given. In addition, the performance of labyrinth weirs when the structure placed in an angle to the approaching flow (inclined labyrinth weirs) was tested.

Power electronics have a significant role in modern electrical devices, for instance, hybrid electric vehicles. Power electronics are the technology in between the source and the load circuits and can convert the power from dc to ac or from dc to ac. There are also many types of dc-dc converters, like such as boost and buck converters, which exhibit switching ripple behavior. A boost converter increases the output voltage (with respect to the input voltage) and reduces the output current. A buck converter decreases the output voltage and increases the output current. Many models are used to predict the behavior of the boost and buck converters. The detailed (DET), state-space averaged (SSA), and generalized averaging method (GAM) models are capable of predicting the average behavior of dc-dc converters. For DET and GAM models, the rippling behavior can also be predicted. These models differ in terms of required run time, existence of constant equilibrium points, and accuracy. The DET model has a long run time and does not have constant equilibrium, but it is very accurate. The SSA technique is a mathematical and time-invariant model that capable of describing the behavior of a dc-dc boost converters. It can derive the small signal ac equations of a switching converter and is used to illustrate the average behavior of any linear or nonlinear system in converters. The SSA does not take extensive runtime simulation and has constant equilibrium points, and can be applied to continuous, discrete and sample data systems. The GAM model can predict the average and ripple behavior in power electronic systems and has constant equilibrium and fast run time. However, it has a numerical stability issue. The integrator stabilized multifrequency averaging (ISMFA) model is employed to solve the stability issue in the GAM model, but it is a complicated dynamic method and has restrictions in its process. In the present study, a simplified but stable GAM model is introduced to predict the average and ripple behavior of boost dc-dc converters and to overcome the limitations of other methods. In this work, the stabilized GAM model has been used for a dc-dc boost converters. The stability of the proposed model is analyzed. The performance of the improved GAM model is compared with the DET, SSA, and GAM models. The results show that the stabilized GAM model is stable with the additional poles created by the GAM assignable by parameter choice. The new GAM model predicts the same results as the existing GAM method without the underlying stability concerns. The stabilized GAM model exhibits constant ii equilibrium point and requires significantly lower run times than the DET model, but it is also able to predict the ripple performance of the converter. The stabilized GAM model does not take a long run time, is less complicated, has fewer restrictions, has constant equilibrium and internal stability, and has more straightforward implementation than other models, like the ISMFA model. It represents a suitable alternative to DET models when high accuracy simulations are desired without long simulation run times.

In this thesis, the metastable states are studied. The work focuses on a theoretical model of one or two metastable states decaying into a continuum of states which is bounded from below. We examine the time evolution of such systems and how it is affected by the energy of the metastable state(s) and by the position of the poles of the scattering matrix in the complex plane. We also look closely at the spectral line shape. Numerical integration of a system of differential equations is used for solving the problem of the time evolution and spectral line shape while Freshbach-Fano projection operator formalism is used for finding the position of the poles. The results are compared with first order perturbation theory and with semi-analytical formula obtained from adiabatic elimination of the continuum. The last part of the thesis is dedicated to an application of the model on neon-helium-neon cluster. 1

The alluvial forms of the rivers that drain the Colorado Plateau are a product of the water and sediment load that tributaries deliver to the trunk streams. Where the Green and Colorado Rivers cross structural barriers, narrow canyons have been incised. In the steep terrain adjacent to many of these canyons debris flows occur in the catchment basins of tributaries and deliver coarse sediment to the mainstem river corridor. Over time, debris flow deposits have aggraded in trunk stream valleys and created landforms known as debris fans. The sizes of these debris fans are related to the accommodation space available for fan formation. Lithologic variation in the layer-cake stratigraphy of the Colorado Plateau has led to varying valley widths. Tributary catchment, debris fan, depositional site, and mainstem river characteristics are examined over the 156-kilometer reach of the Green River through Desolation and Gray Canyons. Desolation and Gray Canyons provide some of the widest valley widths and resultant debris fan areas on the Colorado Plateau.

Ce travail de thèse explore l’excitation électrique de micro-OLEDs en régime d’impulsion afin d’évaluer la possibilité d’atteindre le seuil laser dans les diodes laser organiques qui restent encore à démontrer. Ils’agit d’identifier des solutions scientifiques et techniques ouvrant la voie vers des densités d’excitations électriques équivalentes aux seuils laser observés en pompage optique. Dans la littérature, les seuils les plus bas sont équivalents à des densités de courant entre 0.72 et 4kA/cm² si on suppose une efficacité quantique externe de 1%. De telles densités de courant imposent un régime d’excitation électrique impulsionnel pour s’affranchir des risques de destructions par effet thermique et des pertes par annihilation singulet-triplet dès lors que l’on travaille avec des durées d’impulsion de l’ordre de la nanoseconde. Et pour espérer des réponses électriques et optiques efficaces à de telles durées d’impulsions, il est proposé ici de combiner l’électronique hyperfréquence et l’optoélectronique organique. A cet effet, un modèle électrique équivalent de l’OLED permettant d’accéder à son temps de réponse en mode tout-ou-rien est développé. De plus, des électrodes spécifiques sont dimensionnées et structurées sous forme de lignes coplanaires d’impédance caractéristique 50Ω afin de maîtriser l’impédance du circuit d’excitation et d’assurer le transfert du maximum d’énergie de l’impulsion d’excitation vers celui-ci. Après dépôts de l’hétéro-structure organique basée sur le système hôte-dopant Alq3:DCM, les composants ainsi réalisés sont caractérisés électriquement et optiquement avec différentes techniques par analyse vectorielle, en régime continu et en régime d’impulsion. En régime d’impulsion de très courtes durées (2.5~20ns) et à faible taux de répétition (100Hz), des temps de réponse de 330ps etdes densités de courant maximales entre 4 et 6kA/cm² ont été mesurés alors que le maximum de luminance culmine à 4.11x10⁶ cd/m². / This thesis explores the pulsed electrical excitation of micro-OLEDs in order to evaluate the possibility of reaching the laser threshold in organic laser diodes that have not yet be demonstrated. The main goal is the identification of the scientific and technical solutions towards high electrical excitation current densities equivalent to the laser thresholds observed under optical pumping. In the literature, the lowest reported thresholds are equivalent to current densities between 0.72 and 4kA/cm², assuming an external quantum efficiency of 1%. Such current densities imply a pulsed electrical excitation regime to prevent the risks of device breakdown by Joule heating effects and to avoid losses by excitons annihilation processes, as long as the pulses duration are in nanosecond range. To expect efficient electrical and optical responses to such pulse durations, it is suggested to combine microwave electronics and organic optoelectronics. For this purpose, an equivalent electrical model of the organic light emitting device, allowing access to its on-off mode time response, is developed. Additionally, specific electrodes are designed and patterned in the coplanar waveguide configuration with characteristic impedance of 50Ω, inorder to control the impedance of the excitation circuit and to ensure the maximum energy transfer of the excitation pulse to the device. After deposition of organic hetero-structure based on the Alq3:DCM host-guest system, the device is characterized electrically and optically with different techniques by vector network analysis, in continuous mode and in pulse mode. In pulse excitation regime with very short pulses durations (2.5~20ns) and low repetition rate (100Hz), time response of 330ps and maximum current densities between 4 and 6kA/cm² are recorded while the maximum of luminance peaks at 4.11x10⁶ cd/m².