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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.
101

Factors Related to the Timing of Intestinal Stoma Closure and Outcomes after the Surgery

Wu, Chin-Yu 05 February 2011 (has links)
Patients of stoma caused by the colorectal disease or trauma are increasing and most of the patients are keen to have their stoma closed as early as possible to lower the burdens in their life. However, stoma often associated with complications such as wound. The interval between constructing and closing of stoma is still controversial. This study will figure out a way to predict an appropriate timing of stoma closure to get better outcome by using NHI database, from January 1, 2007 to December 31, 2008, in Taiwan. In 463 stoma closure patients, mean age: 65.94 years, ratio of male to female: 1.66, 70.19% Colostomy, 29.81% Ileostomy, mean timing: 156.73 days, mean length of stay: 10.81 days, mean fees: 57,698.06 TWD, only one death in hospital, 35 readmission within 30 days after discharged; with £\ = 0.05 level, the timing is significant in comorbidity, primary diagnosis; the outcomes are associated with the timing of stoma closure, comorbidity, patients¡¦ age and gender, hospital ownership and physician annual volume. Through this study, a perfect timing of stoma closure should be determined by the characteristics of patient and physician. Physicians could predict the timing through the stratified analysis and well organize the resource of hospital to improve the quality of medical care.
102

Simulation of nonlinear internal wave based on two-layer fluid model

Wu, Chung-lin 25 August 2011 (has links)
The main topic of this research is the simulation of internal wave interaction by a two-dimensional numerical model developed by Lynett & Liu (2002) of Cornell University, then modified by Cheng et al. (2005). The governing equation includes two-dimensional momentum and continuity equation. The model uses constant upper and lower layer densities; hence, these factors as well as the upper layer thickness. Should be determined before the simulation. This study discusses the interface depth and the density according to the buoyancy frequency distribution, the EOF, and the eigen-value based on the measured density profile. Besides, a method based on the two-layer KdV equation and the KdV of continuously-stratified fluid. By minimize the difference of linear celeriy, nonlinear and dispersion terms, the upper layer thicknes can also be determined. However, the interface will be much deeper than the depth of max temperature drop in the KdV method if the total water depth is bigger than 500 meters. Thus, the idealization buoyancy frequency formula proposed by Vlasenko et al. (2005) or Xie et al. (2010) are used to modify the buoyancy frequency. The internal wave in the Luzon Strait and the South China Sea are famous and deserves detailed study. We use the KdV method to find the parameters in the two fluid model to speed up the simulation of internal wave phenomena found in the satellite image.
103

Stratified flow and turbulence over an abrupt sill /

Klymak, Jody Michael. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 147-153).
104

Folding of stratigraphic layers in ice domes /

Jacobson, Herbert Paul. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 104-108).
105

Outcrop analysis of ooid grainstones in the Permian Grayburg Formation, Shattuck Escarpment, New Mexico

Parker, John Alexandre 01 November 2013 (has links)
Ooid grainstone reservoir architecture remains poorly understood, particularly because of sedimentologic and stratigraphic heterogeneities that are innate to grainstone body development. Understanding of Geospatial relationships and recovery of hydrocarbons from these significant reservoir facies can be improved with access to outcrop analog information from well exposed examples. Object-based models and other modern subsurface reservoir models are considered superior methods for portraying realistic sediment distributions. These models, however, are highly dependent on input data describing sediment-body geometry for faithful template generation. Such input data are notably rare in carbonate systems. Maps generated from modern depositional patterns give a first approximation of areal distribution, but they are not as useful for understanding final preserved stratigraphic thickness and internal facies, sedimentary structure, and grain-type patterns. For this purpose, studies of exceptional outcrops are required. The 18 km long oblique-dip-oriented wall of the Shattuck Escarpment provides such a unique exposure of Permian-age grainstones. The Shattuck Escarpment in the Guadalupe Mountains provides an oblique-dip profile that exposes a near-complete middle Permian Grayburg mixed clastic-carbonate shelf succession of three high-frequency sequences which contain 30 high-frequency cycles. Particularly important for this study are the four cycles that display full updip to downdip extents of ooid grainstone tidal bar and tidal delta objects. The data from the Shattuck wall presented in this paper focusses on the transgressive portion of the upper Grayburg, or G12 high-frequency sequence (HFS), located 5 km landward of the time-equivalent shelf margin. This interval is an analog for productive fields along the northwest shelf of the Delaware Basin and on the eastern flank of the Central Basin Platform. The goal of this project is to understand the sedimentology and facies/cycle architectural variability of tidally influenced shelf crest ooid grainstones of the Grayburg Formation. Comparing this outcrop data to modern grainstone deposits allows the reader to understand the small-scale and large-scale sedimentologic and architectural patterns in analogous subsurface ooid grainstone reservoirs. Spatial analysis of these cycles was carried out using measured sections and GigaPan (high resolution photomosaic) data. Petrophysical (Porosity and Permeability) data was collected from three separate vertical core plug transects approximately 1 km apart with a vertical resolution of 30 cm. Cycle-set-scale grainstone complexes up to 6m thick extend at least 4.25 km along depositional dip and show variations in permeability between 6-400 mD and porosities between 8-20% within the lower portions of the grainstone complex. / text
106

Merit Making, Money and Motherhood : Women's Experiences of Commercial Surrogacy in Thailand

Nilsson, Elina January 2015 (has links)
This thesis explores transnational commercial surrogacy in the context of Thailand, with the specific purpose to examine Thai women’s motives and experiences of being a surrogate mother. The study is based on two months of fieldwork in Bangkok between June and August 2014 during which interviews were conducted with eleven former, current or future surrogate mothers. The analysis take a postcolonial feminist approach, and draw upon theory of motherhood, intimate labor and stratified reproduction. The study shows how the women’s account of why they want to become a surrogate mother is influenced by contemporary cultural and moral values regarding motherhood and womanhood. By being a surrogate mother they live up to the ideal role of the nurturing mother and the dutiful daughter. Furthermore, the women’s experiences of the pregnancy and their position in the arrangement is characterized by worry, uncertainty, and mistrust. This is partly due to how their rights and opinions are deemed less significant than those of the intended parents. The women are also severely limited in their say over various aspects of the pregnancy. Even though the surrogate mothers have made conscious decisions without being persuaded by family or friends, the study shows that they are still in an exposed position within an arrangement that is characterized by uneven power relations. This is further shown by locating the surrogate mothers’ stories and experiences in relation to other stakeholders and within the larger context of commercial surrogacy in Thailand, as well as on a global level.
107

DYNAMICS OF INTERNAL SOLITARY WAVE AND BOTTOM BOUNDARY INTERACTION

AGHSAEE, PAYAM 10 January 2012 (has links)
The breaking of internal solitary waves (ISWs) of depression shoaling upon a uniformly sloping boundary in a smoothed two-layer density field was investigated using high-resolution two-dimensional simulations. The simulations were performed for a wide range of boundary slopes S∈[0.01,0.3] and wave slopes. Over steep slopes (S≥0.1), three distinct breaking processes were observed; surging, plunging and collapsing breakers which are associated with reflection, convective instability and boundary layer separation, respectively. Over mild slopes (S≤0.05), nonlinearity varies gradually and the wave fissions into a train of waves of elevation after it passes through the turning point where solitary waves reverse polarity. The dynamics of each breaker type were investigated and the predominance of a particular mechanism was associated with a relative developmental timescale. The breaker type was characterized in wave slope S_w versus S space and the reflection coefficient (R), modeled as a function of the internal Iribarren number, was in agreement with other studies. The same 2D model was applied to investigate boundary layer separation-driven global instability, which is shown to play an important role in breaking of shoaling ISWs. The simulations were conducted with waves propagating over a flat bottom and shoaling over relatively mild (S=0.05) and steep (S=0.1) slopes. Combining the results over flat and sloping boundaries, a unified criterion for vortex shedding is proposed, which depends on the momentum thickness Reynolds number and the non-dimensionalized ISW-induced pressure gradient at the point of separation. The criterion is generalized to a form that may be readily computed from field data and compared to published laboratory and field observations. During vortex shedding, the bed shear stress, vertical velocity and near-bed Reynolds stress were elevated, implying potential for sediment re-suspension. Laboratory experiments were also performed to study three-dimensionality (3D) of global instability. Our results agree with previous laboratory experiments, using the proposed pressure gradient parameter and Reynolds number. The 3D effects prevent the vortices from ascending as high as they do in 2D simulations. The instabilities were not able to re-suspend sediments with 20 µm median diameters, which suggests applying lighter sediments, as finer sediments will be cohesive and dynamically different. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-12-23 15:03:29.76
108

Aplicabilidade dos conceitos de competência do escoamento e de capacidade de transporte às correntes de turbidez

Buffon, Patricia January 2018 (has links)
Os conceitos de competência do escoamento e de capacidade de transporte foram desenvolvidos para escoamentos fluviais e acabam sendo transferidos para a modelagem de correntes de turbidez. No entanto, não é claro até que ponto o estabelecimento de analogias entre o ambiente fluvial e as correntes de turbidez pode ser realizado. Nesse contexto, o principal objetivo deste trabalho foi avaliar os conceitos de competência e de capacidade nas correntes de turbidez. O estudo foi desenvolvido experimentalmente, em um canal de inclinação variável de 4 m de comprimento, 40 cm de altura e 12 cm de largura. Um leito móvel foi construído em um trecho intermediário do canal utilizando sedimento - carvão mineral (ρ = 1405 kgm³) - com tamanho areia média. No total, 30 simulações de correntes de turbidez contínuas foram realizadas, utilizando o mesmo sedimento, porém com tamanho areia muito fina. Foram simuladas três declividades diferentes (6%, 0,3% e 0,015%), vazões de injeção entre 15 e 25 lmin, concentrações iniciais variando entre 0,03% e 5,5% e a duração dos ensaios ficou compreendida entre 3 e 30 min. O levantamento do perfil longitudinal do leito móvel, antes e após o ensaio, foi realizado e todo o sedimento foi coletado. Três quantidades distintas de sedimento foram quantificadas: a quantidade depositada antes do leito móvel, a quantidade depositada no leito móvel e a quantidade depositada depois do leito móvel. O cálculo da eficiência de transporte das correntes de turbidez no trecho do leito móvel, bem como das suas descargas sólidas, foi realizado. Também foram realizadas análises granulométricas do sedimento depositado antes e após do leito móvel. Por fim, parâmetros do fluxo foram obtidos (altura e velocidade) através de análises visuais e números adimensionais clássicos do transporte sólido em canais abertos foram avaliados. A partir da interpretação dos dados, conclui-se que os conceitos de competência do escoamento e de capacidade de transporte não foram capazes de refletir o diâmetro característico do sedimento transportado pelas correntes simuladas e a capacidade máxima de transporte desses fluxos, como normalmente ocorre em escoamentos fluviais. A relação entre a eficiência de transporte desses fluxos e a descarga sólida dos mesmos indicou que a partir de uma região a eficiência tornou-se invariante. Essa relação possui curvas com tendência logarítmica e as suas assíntotas ocorreram em valores de eficiência da ordem de 50% (inclinação de 6%) e de 40% (inclinações de 0,3% e 0,015%). A relação entre o diâmetro característico do sedimento depositado depois do leito e antes do leito indicou uma diminuição de cerca de 18% no tamanho dos grãos depositados a jusante. / The modeling of turbidity currents uses the concepts of competence and flow capacity that have been developed based on river hydraulics. However, the analogies between the fluvial environment and turbidity currents are not very clear. The main purpose of this study was to evaluate the competence and flow capacity of turbidity currents. The study was performed using an experimental channel 4 m long, 40 cm high, and 12 cm wide with variable slope. A mobile bed of medium sand-size - mineral coal (ρ=1405 kgm³) - was constructed in an intermediate area of the channel. In total, 30 simulations of continuous turbidity currents were performed and the sediment used in the turbidity currents was very fine sand-size mineral coal. The simulations were accomplished considering three different channel slopes (6%, 0.3% e 0.015%); injection discharge varied between 15 and 25 l/min, and initial volumetric concentrations varied between 0.03% and 5.5%. The simulations lasted between 3 and 30 minutes. The longitudinal profile of the mobile bed was analyzed before and after each simulation, and all the sediment was collected at the end. Three different amounts of sediment were quantified: the amount of sediment deposited before, on, and after the mobile bed. Based on this data, both the transport efficiency and solid discharge of the turbidity current on the mobile bed were determined. Particle-size distribution of the deposited sediment before and after the mobile bed was also carried out. Finally, flow parameters were obtained (high and velocity) considering visual evaluation and the classical dimensional numbers in sediment transport in open channel flows were analyzed. The data interpretation revealed that the competence and flow capacity parameters were not able to reflect the grain diameter transported by the simulated currents and a maximum flow capacity of these flows, as usually is observed in fluvial flows. The relation between the transport efficiency and solid discharge of these flows demonstrated that after a certain point, the efficiency became constant. This relation resulted in log trend curves with asymptotes located at efficiency values of approximately 50% (6% slope) and 40% (0.3% and 0.015% slopes). The characteristic diameter of the sediment deposited after the mobile bed presented a reduction of 18% when compared to the sediment deposited before the mobile bed.
109

Aplicabilidade dos conceitos de competência do escoamento e de capacidade de transporte às correntes de turbidez

Buffon, Patricia January 2018 (has links)
Os conceitos de competência do escoamento e de capacidade de transporte foram desenvolvidos para escoamentos fluviais e acabam sendo transferidos para a modelagem de correntes de turbidez. No entanto, não é claro até que ponto o estabelecimento de analogias entre o ambiente fluvial e as correntes de turbidez pode ser realizado. Nesse contexto, o principal objetivo deste trabalho foi avaliar os conceitos de competência e de capacidade nas correntes de turbidez. O estudo foi desenvolvido experimentalmente, em um canal de inclinação variável de 4 m de comprimento, 40 cm de altura e 12 cm de largura. Um leito móvel foi construído em um trecho intermediário do canal utilizando sedimento - carvão mineral (ρ = 1405 kgm³) - com tamanho areia média. No total, 30 simulações de correntes de turbidez contínuas foram realizadas, utilizando o mesmo sedimento, porém com tamanho areia muito fina. Foram simuladas três declividades diferentes (6%, 0,3% e 0,015%), vazões de injeção entre 15 e 25 lmin, concentrações iniciais variando entre 0,03% e 5,5% e a duração dos ensaios ficou compreendida entre 3 e 30 min. O levantamento do perfil longitudinal do leito móvel, antes e após o ensaio, foi realizado e todo o sedimento foi coletado. Três quantidades distintas de sedimento foram quantificadas: a quantidade depositada antes do leito móvel, a quantidade depositada no leito móvel e a quantidade depositada depois do leito móvel. O cálculo da eficiência de transporte das correntes de turbidez no trecho do leito móvel, bem como das suas descargas sólidas, foi realizado. Também foram realizadas análises granulométricas do sedimento depositado antes e após do leito móvel. Por fim, parâmetros do fluxo foram obtidos (altura e velocidade) através de análises visuais e números adimensionais clássicos do transporte sólido em canais abertos foram avaliados. A partir da interpretação dos dados, conclui-se que os conceitos de competência do escoamento e de capacidade de transporte não foram capazes de refletir o diâmetro característico do sedimento transportado pelas correntes simuladas e a capacidade máxima de transporte desses fluxos, como normalmente ocorre em escoamentos fluviais. A relação entre a eficiência de transporte desses fluxos e a descarga sólida dos mesmos indicou que a partir de uma região a eficiência tornou-se invariante. Essa relação possui curvas com tendência logarítmica e as suas assíntotas ocorreram em valores de eficiência da ordem de 50% (inclinação de 6%) e de 40% (inclinações de 0,3% e 0,015%). A relação entre o diâmetro característico do sedimento depositado depois do leito e antes do leito indicou uma diminuição de cerca de 18% no tamanho dos grãos depositados a jusante. / The modeling of turbidity currents uses the concepts of competence and flow capacity that have been developed based on river hydraulics. However, the analogies between the fluvial environment and turbidity currents are not very clear. The main purpose of this study was to evaluate the competence and flow capacity of turbidity currents. The study was performed using an experimental channel 4 m long, 40 cm high, and 12 cm wide with variable slope. A mobile bed of medium sand-size - mineral coal (ρ=1405 kgm³) - was constructed in an intermediate area of the channel. In total, 30 simulations of continuous turbidity currents were performed and the sediment used in the turbidity currents was very fine sand-size mineral coal. The simulations were accomplished considering three different channel slopes (6%, 0.3% e 0.015%); injection discharge varied between 15 and 25 l/min, and initial volumetric concentrations varied between 0.03% and 5.5%. The simulations lasted between 3 and 30 minutes. The longitudinal profile of the mobile bed was analyzed before and after each simulation, and all the sediment was collected at the end. Three different amounts of sediment were quantified: the amount of sediment deposited before, on, and after the mobile bed. Based on this data, both the transport efficiency and solid discharge of the turbidity current on the mobile bed were determined. Particle-size distribution of the deposited sediment before and after the mobile bed was also carried out. Finally, flow parameters were obtained (high and velocity) considering visual evaluation and the classical dimensional numbers in sediment transport in open channel flows were analyzed. The data interpretation revealed that the competence and flow capacity parameters were not able to reflect the grain diameter transported by the simulated currents and a maximum flow capacity of these flows, as usually is observed in fluvial flows. The relation between the transport efficiency and solid discharge of these flows demonstrated that after a certain point, the efficiency became constant. This relation resulted in log trend curves with asymptotes located at efficiency values of approximately 50% (6% slope) and 40% (0.3% and 0.015% slopes). The characteristic diameter of the sediment deposited after the mobile bed presented a reduction of 18% when compared to the sediment deposited before the mobile bed.
110

Álgebras estandarmente estratificadas e álgebras quase-hereditárias / Standardly stratified algebras and quasi-hereditary algebras

Paula Andrea Cadavid Salazar 28 November 2007 (has links)
Sejam K um corpo algebricamente fechado, A uma K-álgebra básica conexa de dimensão finita sobre K e ê=(e_1,e_2,... ,e_n) um conjunto completo de idempotentes ortogonais, primitivos e ordenados de A. O conjunto dos módulos estandares é o conjunto Delta ={ D_1, ..., D_n }, onde D_i é o quociente maximal do A-módulo projetivo P_i com fatores de composição simples S_j, com j\\leq i, F(Delta) é a subcategoria plena de mod A dos módulos têm uma Delta-filtração. Se A_A esta em F(Delta) diz-se que A é uma álgebra estandarmente estratificada. Se, além disso, para cada elemento em Delta vale que End_A(D_i) é isomorfo a K diz-se que A é uma álgebra álgebra quase-hereditária. Nesta dissertação estudamos as propriedades de F(Delta), especialmente quando A é estandarmente estratificada, e algumas condições necessárias e suficientes para que A seja quase-hereditária. / Let K be an algebraically closed field, A a basic, connected, finite dimensional K-algebra and ê=(e_1,e_2,...,e_n) a complete set of ordered primitive orthogonal idempotents of A. The set of standard modules is the set Delta={D_1, ..., D_n}, where D_i is the maximal factor submodule of P_i whose composition factors are isomorphic to S_j, for j\\leq i. We denote by F(Delta) the full subcategory of mod A containing the modules which are filtered by modules in Delta. If iA_A is in F(Delta) we say that A is standardly stratified. Moreover, if End_A(D_i) is isomorphic with K, for each element in Delta we say that A is quasi hereditary. In this work we study the properties of the category F(Delta), especially when A is stardardly stratified, and some necessary and sufficient conditions to A be quasi hereditary.

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