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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.
151

The Effects Of Early Postnatal Ethanol Intoxication On Retina Ganglion Cell Morphology And The Development Of Retino-geniculate Projections In Mice

Dursun, Ilknur 01 February 2010 (has links) (PDF)
Experimental and clinical data have documented the adverse effects of perinatal ethanol intoxication on peripheral organs and the central nervous system. There is little known, however, about potential damaging effects of perinatal ethanol on the developing visual system. The purpose of this study was to examine the effects of neonatal ethanol intoxication on RGC morphology, estimate the total number of neurons in RGC layer and dorsolateral geniculate nucleus (dLGN), and on the eye-specific fiber segregation in the dLGN), in YFP and C57BL/6 mice pups. Ethanol (3 g/kg/day) was administered by intragastric intubation throughout postnatal days (PD) 3-20 or 3-10. Intubation control (IC) and untreated control (C) groups were included. Blood alcohol concentration (BAC) was measured in separate groups of pups on PD3, PD10, and PD20 at 4 different time points, 1, 1.5, 2 and 3 h after the second intubation. Numbers neurons in the RGCs and dLGN were quantified on PD10, PD20 using unbiased stereological procedures. The RGC images were taken using a confocal microscope and images were traced using Neurolucida software. On PD9, intraocular injections of cholera toxin-
152

A Prestress Based Approach To Rotor whirl

Pradeep, M 09 1900 (has links)
Rotordynamics is an important area in mechanical engineering. Many machines contain rotating parts. It is well known that rotating components can develop large amplitude lateral vibrations near certain speeds called critical speeds. This large amplitude vibration is called rotor whirl. This thesis is about rotor whirl. Conventional treatments in rotordynamics use what are called gyroscopic terms and treat the rotor as a one-dimensional structure (Euler-Bernoulli or Timoshenko) with or without rigid masses added to them. Gyroscopic terms are macroscopic inertial terms that arise due to tilting of spinning cross-sections. This approach, while applicable to a large class of industrially important rotors, is not applicable to a general rotor geometry. In this thesis we develop a genuine continuum level three dimensional formulation for rotordynamics that can be used for many arbitrarily shaped rotors. The key insight that guides our formulation is that gyroscopic terms are macroscopic manifestations of the prestress induced due to spin of the rotor. Using this insight, we develop two modal projection techniques for calculating the critical speed of arbitrarily shaped rotors. These techniques along with our prestress based formulation are the primary contributions of the thesis. In addition, we also present two different nonlinear finite element based implementations of our formulation. One is a laborious load-stepping based calculation performed using ANSYS (a commercially available finite element package). The other uses our nonlinear finite element code. The latter two techniques are primarily developed to provide us with an accurate answer for comparison with the results obtained using the modal projection methods. Having developed our formulation and the subsequent modal projection approximations, we proceed to validation. First, we analytically study several examples whose solutions can be easily obtained using routine methods. Second, we consider the problem of a rotating cylinder under axial loads. We use a semi-analytical approach for this problem and offer some insights into the role played by the chosen kinematics for our virtual work calculations. The excellent match with known results obtained using Timoshenko theory validates the accuracy of our formulation. Third, we consider several rotors of arbitrary shape in numerical examples and show that our modal projection methods accurately estimate the critical speeds of these rotors. After validation, we consider efficiency. For axisymmetric rotor geometries, we implement our formulation using harmonic elements. This reduces the dimension of our problem from three to two and considerable savings in time are obtained. Finally, we apply our formulation to describe asynchronous whirl and internal viscous damping phenomena in rotors.
153

Education through Maps : The Challenges of Knowing and Understanding the World

Hennerdal, Pontus January 2015 (has links)
The overall purpose of this thesis is to study, in relation to geography education and with a historical perspective, the challenges of knowing and understanding the world. The cases are all from Sweden. In the first paper, educational ideas in the nineteenth and early twentieth centuries are studied, and the results indicate that some of the previously criticised educational ideas that were perceived as resulting from the ideas of nineteenth century regional geography in fact can be observed in earlier centuries and were criticised during the nineteenth century. In the second paper, school children’s ability to locate geographical names on outline maps is compared with children’s ability to complete the same task 45 years earlier. A total of 1,124 students were included in the latter study, and the results were compared with those from a study of 1,200 students from the same town conducted in 1968. The results raise questions regarding the picture of the continuous decline in children’s school results and show, for example, that children today are better at locating continents on a world map. The final paper identifies a new aspect of map reading difficulties. These difficulties in map reading are increasingly important in our global society, i.e., how the edges of the world map cohere. The paper shows that many map readers, children and adults, respond according to the idea of linear peripheral continuity, which indicates that the proposed continuation is along the straight line that continues tangentially to the original route when it crosses the edge. In general, this understanding leads to incorrect interpretations of the continuation of world maps. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Accepted.</p>
154

Comparaisons de projections des niveaux d'incapacité de la population canadienne de 65 ans et plus en 2031

Bellehumeur, Patrick 01 1900 (has links)
Le vieillissement de la population canadienne prévisible dans les prochaines années entrainera d’importants changements au point de vue social. L’un d’eux est l’augmentation fulgurante du nombre d’aînés en état d’incapacité. Utilisant le modèle de microsimulation LifePaths, cette recherche compare deux projections, ayant des méthodologies différentes, du nombre d’individus en incapacité de 65 ans et plus vivant en ménage privé en 2031. La première méthode utilise le module d’incapacité de LifePaths pour générer les individus en incapacité tandis que la seconde méthode utilise plutôt une régression logistique ordonnée pour les obtenir. Les projections du nombre d’individus en état d’incapacité des deux méthodes nous permettent une comparaison entre ces résultats. Suite à l’élaboration de tableaux et de graphiques permettant de tracer un portait de la situation, cette recherche essaie de démystifier les sources possibles à l’origine de ces différences. Les résultats montrent d’importantes différences entre les projections, spécifiquement pour les individus en état d’incapacité sévère. De plus, lorsqu’on s’intéresse aux variables d’intérêts, on remarque que les différences de projections d’effectifs sont importantes chez les hommes et les gens mariés. Par contre, lorsque les proportions sont analysées, c’est plutôt le groupe d’âges 80 ans et plus ainsi que les projections pour la province du Québec qui créent problème. Ces différences sont attribuables aux caractéristiques d’un modèle de microsimulation, aux populations de départ ainsi qu’aux paramètres définis. Les résultats démontrés dans cette recherche mettent en garde sur les travaux étudiant le nombre d’individus en incapacité dans le futur. Nos deux méthodes ayant des résultats différents, nous ne pouvons pas conclure avec certitude quelle sera la situation dans le futur. / Population ageing in Canada in the forth coming years will bring important changes from the social viewpoint. One of them will be the increasing number of disabled older people. Using the microsimulation Lifepaths model, the study compares two projections, each having a different methodology, of the number of disabled individuals aged 65 and over and living in the community in 2031. The projections were produced using different methodologies. The first method uses the disability module of Lifepaths to generate those disabled older population while the second method uses an ordered logistic regression model. Then, we compare the results between the methods. Furthermore, this research paper attempts to identify the possible causes leading to the differences with appropriate graphs and tables. The results show important differences between the projections, especially for the number of severe disabled individuals. We note important difference for men and married people. Also the age groupe 80 years and older and the projection for de province of Quebec is problematic.These could be the attributed to the characteristics of a microsimulation model, the population at the base as well as the defined parameters. Both methods have different results, we cannot conclude what will be the situation in the future.
155

Méthode des réseaux en analyse de données, application à l'analyse de concordance

Tricot, Jean-Marie 29 June 1990 (has links) (PDF)
Dans les différents domaines de la statistique descriptive, les données se présentent sous forme de nuages de points; sur ceux-ci, on est souvent amené à faire des études de proximité ou, plus généralement, de similarité, permettant de faire des analyses de structure. Il en est ainsi en analyse de concordance où il s'agit d'apprécier le degré d'accord entre d observateurs évaluant le même ensemble de n sujets au moyen d'une échelle de valeurs possibles prises par une variable (on peut généraliser le problème à plusieurs variables).
156

Short-Term Enrollment Projections Based on Traditional Time Series Analysis

Brooks, Dorothy Lynn 12 1900 (has links)
The problem of this study was to make short-term projections of student semester credit hour enrollments, at each of two state universities of comparable size, based on traditional time series analysis. 1. The first purpose of the study was to identify the cyclical component of deseasonalized enrollment data. 2. The second purpose was to determine a cyclical economic indicator having a high correlation with the cyclical component of the enrollment data. The selected economic indicator was used in establishing explanatory equations for projecting enrollment. 3. The third purpose was to compare projected 1979- 1980 academic year enrollment figures obtained from explanatory equations for each institution with actual enrollment figures of each institution for that year. 4. The fourth purpose was to compare the explanatory equations developed for the two institutions and the projections of student semester credit hour enrollments they yielded. 5. The fifth purpose was to discuss enrollment projections for each institution and the uses of enrollment projections in planning.
157

Developing whole-life cost models for retrofit options in office buildings

Tokede, Olubukola O. January 2016 (has links)
Office retrofit building projects have become a subject of increased attention among building researchers in the United Kingdom, and in many economically advanced nations. Existing whole-life costing models have however, not proven to be robust enough to deal with these retrofit building scenarios. There is a growing body of evidence that conceptual modifications in the mechanics of whole-life cost modelling, could facilitate improvements in the long-term cost assessment of buildings. Recent research has made a case for the existence of revocability and disruption, in the appraisal of retrofit building investments. Revocability, connotes the potential for variability, in the future cost projections of a building over its estimated life. Disruption relates to the diminished building use, or unusability, over a period of implementing a retrofit initiative. Existing whole-life cost models have however, not recognised the implications of revocability and disruption in their framework. This study conducts an investigation into the whole-life costing of office retrofit building projects, and develops a Fuzzy New-Generation Whole-life Costing approach. Two office retrofit building projects are adopted, to appraise the identified issues in the whole-life costing framework. A number of building configuration permutations (BCPs) constituting different retrofit options, are developed in both projects. The potential implication of revocability and disruption, are evaluated based on probability and fuzzy logic principles respectively. Sensitivity analysis is applied to discount rate assumptions over the estimated lives, of the projects considered. The Spearman's rank correlation coefficient is used in analysing the ranking results of selected projects. This provided an assessment of the relative preference of BCPs in the projects. Results from the case studies show 1) disruption issues account for up to 12% of initial capital costs; 2) revocability accounts for up to 35% of initial capital cost, over a 20-year life; up to 119%, over a 60-year life; 3) up to 2% underestimation in the whole-life cost, over a 20-year life; and up to 45% underestimation, over a 60-year period, in the SPACE project; 4) up to 9% underestimation in the whole-life cost, over a 20-year life; and up to 53% underestimation, over a 60-year life, in the MS project.
158

Simulação estocástica dos impactos das mudanças climáticas sobre as demandas de água para irrigação na região noroeste do Rio Grande do Sul

Melo, Tirzah Moreira de January 2015 (has links)
Esta tese foi desenvolvida para avaliar os impactos das mudanças climáticas ao longo deste século sobre as demandas futuras de água para irrigação da soja na região Noroeste do Estado do Rio Grande do Sul sob uma abordagem estocástica e considerando diferentes projeções de modelos climáticos para o período de 2011-2100, comparando com o passado (1961-1990). As demandas de água para irrigação da soja (IWR) foram obtidas por simulação com o modelo SWAP. O aspecto estocástico desta avaliação foi conduzido pela incorporação da variabilidade espacial da condutividade hidráulica do solo (Ksat) e dos parâmetros da curva de retenção de água no solo (CR). Inicialmente, foi realizada uma análise estocástica destes atributos físico-hidráulicos na bacia do Arroio Donato (1,1 Km2), a qual serviu de área representativa dos solos e do uso do solo da região Noroeste. Foi empregada a técnica de simulação sequencial Gaussiana (SSG) para geração de 100 campos aleatórios de cada variável. Os resultados revelaram maiores incertezas para Ksat e o parâmetro α da CR e permitiu identificar que a grande heterogeneidade espacial e temporal das variáveis analisadas pode estar associada a fatores tais como clima, manejo e cobertura do solo, erros de amostragem, adensamento da malha amostral e também ao grau de compactação do solo. Em seguida foi feita uma investigação para detectar mudanças nos padrões de temperatura (T) e precipitação (P) na região Noroeste do RS (~65.000 Km2) pelo uso de diferentes modelos climáticos de circulação geral e regional (MCGs e MCRs, respectivamente). Sete distintas localizações na região foram consideradas, para as quais há dez diferentes projeções climáticas destes modelos. Adicionalmente, também foram investigadas a frequência e a intensidade de eventos de precipitação extrema utilizando-se de índices de eventos extremos. As projeções indicam um aumento na média anual de temperatura de quase 3ºC até o final do século, bem como um aumento na precipitação anual. Também foi realizada uma análise sazonal de T e P, a qual demonstrou que os maiores aumentos de temperatura são projetados para o inverno e início da primavera e, portanto, não coincidem com os meses de verão da principal cultura da região (soja). De posse das informações anteriores, o modelo SWAP foi utilizado para estimar as demandas de água para irrigação da soja (IWR), sem considerar perdas devido à eficiência de qualquer método de irrigação. Foram feitos também testes de hipóteses sobre as séries de IWR simuladas e os resultados suportam a premissa de que IWR a curto prazo (2025s) não será estatisticamente diferente do período base (1961-1990). Por outro lado, as IWR em 2055s e 2085s rejeitam esta hipótese. Por fim, avaliou-se a influência da distribuição espacial da condutividade hidráulica saturada (Ksat) e dos parâmetros do modelo da curva de retenção de água no solo (α, n e sat) sobre as demandas futuras de água para a irrigação da soja (IWR), segundo uma abordagem estocástica. Os valores simulados pelo método geoestatístico de simulação sequencial Gaussiana foram utilizados como dados de entrada no modelo SWAP. Como dados meteorológicos foram consideradas apenas as projeções do modelo climático regional ETA 20 e ETA 40 CTRL, bem como as projeções dadas pelo modelo climático global HADCM3 nas sete localizações na região. As estimativas obtidas pelo método estocástico foram então comparadas com as estimativas de IWR obtidas sem considerar a variabilidade espacial dos atributos físico-hidráulicos do solo. Os resultados indicaram grande variabilidade espacial dos valores de IWR. Além disso, observou-se que as menores incertezas de IWR foram obtidas a partir das projeções do modelo de melhor resolução espacial, o ETA 20, enquanto o modelo HADCM3 revelou as maiores diferenças entre os períodos futuros e o período atual (base). Os resultados também demonstraram que a maior incerteza é devido aos modelos climáticos, pois a abordagem estocástica praticamente não agregou incerteza aos valores de IWR simulados anteriormente. Por fim, as séries de IWR obtidas pela abordagem determinística e estocástica foram comparadas pelo teste de hipóteses de Kolmogorov-Smirnov, o qual comprovou que as séries só não diferem a curto prazo (2025s) e que, portanto, a variabilidade espacial do solo não pode ser negligenciada nas estimativas desta variável. / This Thesis has been developed to assess the impacts of climate change throughout this century on future water demands for soybean irrigation in the Northwest region of Rio Grande do Sul under a stochastic approach and considering different projections of climate models for the period 2011-2100, compared to the past (1961-1990). The water demands for irrigation (IWR) were obtained by simulation with the SWAP model. The stochastic aspect of this evaluation was conducted by incorporating the spatial variability of the saturated hydraulic conductivity (Ksat) and the parameters of the soil water retention curve (CR). Initially, a stochastic analysis of soil physical-hydraulic attributes (Ksat and CR parameters) in the Donato basin (1,1 Km2) was carried out. This basin served as a representative area of soils and land uses of the Northwest region. The Sequential Gaussian Simulation (SSG) technique was used to generate 100 random fields of each variable. The results revealed greater uncertainty for Ksat and for α parameter of the CR and identified that the large spatial and temporal heterogeneity of the variables may be associated with factors such as climate, management and land cover, sampling error, spatial density of the sampling grid and also the degree of soil compaction. After, an investigation was made to detect changes in temperature (T) and precipitation (P) patterns in the Northwest region of RS (~65.000 Km2) by using different global and regional circulation models (GCM and RCM, respectively). Seven distinct locations in the region were considered, for which there are ten different climate projections of these models. Additionally, it was also investigated the frequency and intensity of extreme rainfall events using extreme event indices. Projections indicate an increase in average annual temperature of almost 3 °C by the end of this century, as well as an increase in annual precipitation. It was also performed a seasonal analysis of T and P, which showed that the largest temperature increases are projected for the winter and early spring and, therefore, do not coincide with the summer months the main crop in the region (soy). Making use of the above information, the SWAP model was applied to estimate the water demand for soybean irrigation (IWR), excluding losses due to the efficiency of any method of irrigation. A hypothesis test for the simulated IWR series and the results supports the premise that in short-term IWR (2025s) is not statistically different from base period (1961-1990). On the other hand, IWR in 2055s and 2085s reject this hypothesis. Finally, the influence of the spatial distribution of the saturated hydraulic conductivity (Ksat) and the parameters of the soil water retention curve (α, sat and n) on IWR was evaluated, according to a stochastic approach. The simulated values form the geostatistical method of Sequential Gaussian Simulation (SGS) were used as input data in the SWAP model. Input data of meteorological information were provided by the projections of regional climate model ETA 20 and ETA 40 CTRL, as well as the projections given by global climate model HADCM3 for the seven locations in the region. Estimates obtained by the stochastic method were then compared with the IWR estimates obtained without considering the spatial variability of physical and hydraulic soil properties. The results indicated large spatial variability of IWR values. Furthermore, it was observed that the smallest uncertainties of IWR were obtained from the projections with better spatial resolution, the ETA 20 model, while the HADCM3 model revealed the highest differences between future periods and the current period (baseline). The results also showed that the greatest uncertainties are probably due to climate models, since the stochastic approach did not add uncertainties to the IWR values simulated previously. Finally, the series of IWR obtained by stochastic and deterministic approaches were compared by the hypothesis test of Kolmogorov-Smirnov, which proved that only the series in the short term (2025s) differ, and, therefore, the soil spatial variability may not be neglected when estimating this variable.
159

[en] INVERSION OF GEOPHISYCS PARAMETERS IN THREE DIMENSIONS FROM SEISMIC REFLECTION DATA BY HYBRID GENETIC ALGORITHMS / [pt] INVERSÃO DE PARÂMETROS GEOFÍSICOS EM TRÊS DIMENSÕES A PARTIR DE DADOS DE REFLEXÃO SÍSMICA POR ALGORITMOS GENÉTICOS HÍBRIDOS

SAMUEL GUSTAVO HUAMAN BUSTAMANTE 27 February 2009 (has links)
[pt] Este trabalho tem por objetivo investigar um método para auxiliar na quantificação de características sísmicas do subsolo. O modelo sísmico bidimensional de reflexão usa a equação Normal Move Out (NMO), para calcular os tempos de trânsito das ondas sísmicas, tipo P, refletidas em camadas isotrópicas e inclinadas. Essa equação usa a velocidade raiz quadrática média RMS como valor representativo das velocidades intervalares das camadas unidas. No processo de inversão para múlltiplas camadas, as velocidades RMS representam o problema principal para estimar as velocidades intervalares. Conseqüentemente, o método proposto estima sequencialmente os parâmetros do modelo sísmico, para resolver esse problema a partir dos tempos de trânsito com Algoritmos Genéticos Híbridos (algoritmo genético e algoritmo Nelder Mead Simplex). Os tempos de trânsito são sintéticos e a estimação de parâmetros é tratada como um problema de minimização. Com o método proposto foi obtido um alto grau de exatidão, além de reduzir o tempo de computação em 98,4 % em comparação com um método de estimação simultânea de parâmetros. Para aliviar a complexidade e a demora na geração de um modelo em três dimensões se contrói um modelo sísmico em três dimensões formado com modelos bidimensionais, sob cada unidade retangular da malha de receptores do levantamento sísmico, para camadas isotrópicas curvadas, com variações suaves das pendentes e sem descontinuidades. Os modelos bidimensionais formam polígonos que representam as superfícies de interface que são projetadas sob os retângulos da malha. Dois conjuntos de superfícies poligonais são gerados para auxiliar na localização das camadas. / [en] The objective of the present work is to investigate a method to help in the quantification of seismic characteristics underground. The two-dimensional seismic model of reflection employs the equation Normal Move Out (NMO) to calculate the travel times of P waves reflected on inclined and isotropic layers. This equation uses the root mean square velocity as a representative value of the joined layers velocities. At the inversion process, for multiple layers, the root mean square velocities are the main problem to estimate the layer velocities. Consequently, to solve that problem, the proposed method estimates sequentially the parameters of the seismic model using travel times and the Hybrid Genetic Algorithms (Genetic algorithm and the Nelder Mead Simplex algorithm). The travel times are synthetic and the estimation of parameters is treated as a minimization problem. With proposed method was obtained high grade of accurate, and the reduction of 98.4 % of computing time when it was compared to a simultaneous parameters estimation method. For decreasing the complexity and the delay to generate the models in three dimensions is proposed the construction of a three-dimensional seismic model formed with two-dimensional models, under every rectangular cell of the mesh of receptors of the seismic survey, for curved isotropic layers with soft variations in the gradient and without discontinuities. The two-dimensional models form polygons that represent the surfaces of interfaces that are designed under the rectangles of the surface or soil. Two sets of polygonal surfaces are generated to help at the geometric localization of layers.
160

The Zambezi River Basin: Water Resources Management : Energy-Food-Water nexus approach

Sainz, Gabriel January 2018 (has links)
The energy-food-water nexus is of fundamental significance in the goal towards sustainable development. The Zambezi River Basin, situated in southern Africa, currently offers vast water resources for social and economic development for the eight riparian countries that constitute the watershed. Hydropower generation and agriculture are the main water users in the watershed with great potential of expansion, plus urban water supply materialise the largest consumers of this resource. Climate and social changes are pressuring natural resources availability which might show severe alterations due to enhances in the variability of precipitation patterns. This study thus examines the present water resources in the transboundary basin and executes low and high case future climate change incited scenarios in order to estimate the possible availability of water for the period 2060-2099 by performing water balances. Along with projections of water accessibility, approximations on water demands from the main consumer sectors are performed. Results show an annual positive balance for both projected scenarios due to an increase in precipitation during the wet season. They also present a severe increase in overall temperature for the region contributing to a strong increase in evapotranspiration. Projections further inform of an acute increase in water demand for irrigation and urban supply, nevertheless, evaporation from hydropower storage reservoirs continues to exceed water with drawals in volume. Acknowledging the uncertainty contained in this report allows a broader offer of recommendations to be considered when planning for future developments with a sustainable approach. Improvement of hydrological collection systems in the Zambezi basin is indispensable to accomplish a deeper and cohesive understanding of the watershed waterresources. Cooperation and knowledge communication between riparian countries seems to be the right beginning towards social and economic sustainable development for the Zambezi River Basin.

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