Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2009. / Includes bibliographical references (p. 73-78).

Orientador: Pedro Luiz Toledo de Arruda Lourenção / Resumo: Introdução: O diagnóstico da Doença de Hirschsprung (DH) realizado através de biópsias de reto possui alta sensibilidade e especificidade, mas é invasivo, com riscos de complicações. Desta forma, exames de triagem, menos invasivos, servem para indicar quais pacientes devem ser submetidos às biópsias. A identificação da zona de transição (ZT) ao enema opaco permite identificar a transição entre o segmento espástico agangliônico e o cólon dilatado, determinando a extensão da zona agangliônica. Essa análise é subjetiva e relacionada a resultados falsos positivos. Pochaczevsky e Leonidas (1975) propuseram o uso do índice retossigmóide (IRS) ≤ 1,0 (maior diâmetro do reto/ maior diâmetro do sigmóide) para o diagnóstico da DH. O IRS apresenta como vantagem a obtenção de uma medida objetiva e numérica, que pode ser utilizada em conjunto com a identificação da ZT. Após mais de 60 anos de sua descrição inicial e apesar do uso cotidiano na prática clínica, os poucos estudos sobre a capacidade diagnóstica do enema opaco na DH apresentam resultados divergentes. Objetivo: Avaliar a acurácia e aplicabilidade do enema opaco na investigação diagnóstica da DH, pela determinação da ZT e do IRS, comparando seus resultados com os das biópsias de reto. Pacientes e Métodos: Foi realizado um estudo retrospectivo e comparativo, incluindo 43 pacientes submetidos à biópsia de reto para investigação diagnóstica de DH, entre 2010 e 2015, que haviam realizado também enema opaco. Os exames r... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction: The diagnosis of Hirschsprung's disease (HD) performed by rectal biopsies has high sensitivity and specificity, but is invasive, with risks of complications. In this way, less invasive screening tests are used to indicate which patients should undergo biopsies. The identification of the transition zone (TZ) by barium enema allows to identify the transition between the aganglionic spastic segment and the dilated colon, determining the extension of the aganglionic zone. This analysis is subjective and related to false positive results. Pochaczevsky and Leonidas (1975) proposed the use of the rectosigmoid index (RSI) ≤ 1.0 (greater diameter of the rectum / larger diameter of the sigmoid) for the diagnosis of HD. The RSI has the advantage of obtaining an objective and numerical measure, which can be used in conjunction with the TZ identification. After more than 60 years of its initial description and despite daily use in clinical practice, the few studies on the diagnostic capacity of barium enema in HD show divergent results. Objective: To evaluate the accuracy and applicability of the barium enema in the diagnostic investigation of HD, by determining the ZT and the RSI, comparing its results with those of the rectal biopsies. Patients and methods: A retrospective and comparative study was conducted, including 43 patients submitted to rectal biopsy for diagnostic investigation of DH, between 2010 and 2015, who had also performed barium enema. The contrasted radiol... (Complete abstract click electronic access below) / Mestre

Despite challenges with poor emissions and fuel economy, gasoline two stroke engines continue to be developed for a number of applications. The primary reasons for the choice of a gasoline two stroke engine includes its low cost, mechanical simplicity and high specific power output. Some applications for the gasoline two stroke engine include small capacity motorcycles and scooters, off road recreational vehicles, hand held power tools and unmanned aerial vehicles. New technologies, which are already mature in four stroke engines, are now being applied to two stroke engines. Such technologies include direct fuel injection, electronic engine management and exhaust gas after treatment. To implement these new technologies computation models are being continuously developed to improve the design process of engines. Multi-dimensional computational fluid dynamics modelling is now commonly applied to engine research and development, it is a powerful tool that can give great insight into the thermofluid working of an engine. Multi-dimensional tools are however computationally expensive and quasi-dimensional modelling methods are often better suited for the analysis of an engine, for example in transient engine simulation. This thesis reports the development of a new quasi-dimensional combustion model for a loop scavenged two stroke engine. The model differs from other quasi-dimensional models available in the literature as it accounts for a bulk motion of the flame front due to the tumble motion created by the loop scavenge process. In this study the tumble motion is modelled as an ellipsoid vortex and the size of the vortex is defined by the combustion chamber height and a limiting elliptical aspect ratio. The limiting aspect ratio has been observed in experimental square piston compression machines and optical engines. The new model also accounts for a wrinkled flame brush thickness and its effects on the interaction between flame front and combustion chamber. The new combustion model has been validated against experimental engine tests in which the flame front propagation was measured using ionization probes. The probes were able determine the flame front shape, the bulk movement of the flame front due to tumble and also the wrinkled flame brush thickness.

Chan, Man Leung Dunco. / Thesis submitted in: Nov 2008. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 87-91). / Abstracts in English and Chinese. / Abstract --- p.2 / 摘要 --- p.3 / Acknowledgement --- p.4 / Content --- p.5 / List of figures --- p.6 / Chapter Chapter 1 --- Introduction --- p.9 / Chapter 1.1 --- Background --- p.9 / Chapter 1.2 --- Prior work --- p.11 / Chapter 1.3 --- Objectives --- p.13 / Chapter 1.4 --- Proposed method --- p.16 / Chapter 1.5 --- Thesis outline --- p.18 / Chapter Chapter 2 --- Axial curve-pair deformation --- p.19 / Chapter 2.1 --- Axial deformation technique --- p.20 / Chapter 2.1.1 --- Representing objects in axial space --- p.21 / Chapter 2.1.2 --- Defining the frame --- p.23 / Chapter 2.2 --- Axial curve-pair deformation technique --- p.24 / Chapter 2.2.1 --- Framing the curve-pair --- p.25 / Chapter 2.2.2 --- Construction of orientation curve --- p.26 / Chapter 2.2.3 --- Manipulation of the axial curve-pair --- p.28 / Chapter Chapter 3 --- Dynamic axial curve-pair based deformation --- p.32 / Chapter 3.1 --- The dynamic mass spring model --- p.34 / Chapter 3.1.1 --- Dynamic NURBS curve --- p.35 / Chapter 3.1.2 --- Dynamic Free-form deformation --- p.37 / Chapter 3.1.3 --- Dynamic Axial Curve-pair deformation --- p.38 / Chapter 3.2 --- The dynamic mass spring model --- p.41 / Chapter 3.2.1 --- Curve-pair Fitting --- p.41 / Chapter 3.2.2 --- Construction of dynamic curve-pair --- p.44 / Chapter 3.2.3 --- The three-degree torsional spring --- p.48 / Chapter 3.2.4 --- Conserving feature in a twisting deformation --- p.50 / Chapter 3.2.5 --- Comparison of mass spring model --- p.51 / Chapter 3.3 --- Internal and external forces --- p.54 / Chapter 3.3.1 --- Tensile stress --- p.54 / Chapter 3.3.2 --- Torsional stress --- p.55 / Chapter 3.3.3 --- External forces --- p.59 / Chapter 3.4 --- Equations of motion --- p.60 / Chapter 3.5 --- System solver --- p.63 / Chapter 3.6 --- Hierarchical representation --- p.67 / Chapter 3.7 --- Collision detection --- p.72 / Chapter Chapter 4 --- Implementation and experimental result --- p.75 / Chapter 4.1 --- Comparison with original mass-spring system --- p.76 / Chapter 4.2 --- Comparison with dynamic free form deformation --- p.77 / Chapter 4.3 --- Comparison with the axial curve-pair deformation --- p.78 / Chapter 4.4 --- Shape restoring power --- p.80 / Chapter 4.5 --- Applications --- p.81 / Chapter Chapter 5 --- Conclusion --- p.84 / Reference --- p.86

Graphene and structurally similar 2-dimensional (2d) materials such as transition metal dichalcogenides (TMDs) and black phosphorus (BP) hold enormous potential for the next generation optoelectronics and photonics. Pairing 2d materials with printing is an emerging cost-effective large-scale device fabrication strategy. However, the current inks are far from ideal to support reproducible device fabrication. In addition, the instability of BP in ambient limits its applications. In this thesis, I present formulation of 2d material inks for inkjet printing for optoelectronic and photonic applications. To begin with, I produce mono- and few-layer 2d material flakes via ultrasonic assisted liquid phase exfoliation. This allows one-step formulation of a polymer stabilised graphene ink. For TMDs and BP, I design a binary solvent carrier for binder-free ink formulation. I show that these 2d material inks have optimal fluidic properties, drying dynamics and interaction with substrates for spatially uniform, highly controllable and print-to-print consistent large-scale printing on untreated substrates. In particular, the rapid ink drying at low temperatures leads to minimal oxidation of BP during ambient printing; the printed BP with passivation retains a stability over one month. On this basis, the printed graphene is employed as active sensing layer in CMOS integrated humidity sensors and as counter-electrodes in dye-sensitised solar cells, while the printed TMDs and BP are used to develop nonlinear photonic devices (i.e. saturable absorbers for femtosecond pulsed laser generation) and visible to near-infrared photodetectors (e.g. MoS$_2$ and BP/graphene/silicon hybrid photodetectors). Beyond inkjet printing, I present an ink formulation of commercial graphene nanoplatelets for roll-to-roll flexographic press ($\sim$100 m min$^{−1}$ printing speed). This allows hundreds of conductive electronic circuits to be printed in a minute for capacitive touchpads. Though I investigate only graphene, TMDs and BP, the ink formulation strategies can be effortlessly transferred to other 2d materials such as boron nitride, MXenes and mica. In addition to the demonstrated applications, printing of 2d materials can be potentially exploited to fabricate devices such as transistors, light emitters, energy storage conversion, and biosensors. This significantly expands the prospect of printable 2d material optoelectronics and photonics.

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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnologico / Made available in DSpace on 2016-01-08T16:48:45Z (GMT). No. of bitstreams: 1 81185.pdf: 2346116 bytes, checksum: 5a03735b7707061d9b0c603e7a13bb1a (MD5) Previous issue date: 1990 / O presente trabalho apresenta uma metodologia para a solução de escoamentos bi-dimensionais sobre corpos de geometrias arbitrárias, em coordenadas generalizadas usando variáveis co-localizadas. O uso de variáveis co-localizadas não tem recebido a adequada atenção dos analistas numéricos que usam volumes finitos devido as dificuldades inerentes ao acoplamento pressão-velocidades presente nas equações de Navier-Stokes. Se por um lado o uso de variáveis desencontradas introduz o adequado acoplamento entre a pressão e a velocidade para escoamentos incompressíveis, introduz também a necessidade de diferentes volumes de controle para as variáveis dependentes. Para situações tridimensionais, empregando-se coordenadas generalizadas, isto acarreta o armazenamento de um grande número de informações geometricas para cada volume de controle, o que torna inviável o uso de variáveis desencontradas. Associada ao maior armazenamento está a necessidade de um número maior de operações algébricas, como por exemplo, no cálculo dos fluxos mássicos nas interfaces do volume de controle, ocasionando um maior tempo de computação. Neste trabalho é desenvolvido um modelo numérico empregando variáveis co-localizadas que apresenta excelente desempenho quando comparado com o modelo que emprega variáveis desencontradas. O modelo emprega uma linearização do tipo Newton-Raphson para o fluxo de massa, o que permite resolver problemas para escoamentos de alta e baixa velocidades. Para a validação do modelo são analisados problemas bi-dimensionais em coordenadas cartesianas e generalizadas. Em coordenadas cartesianas são analisados os problemas do escoamento a baixa velocidade na região de entrada de um duto constituído de placas paralelas e o problema do escoamento supersônico sobre um anteparo plano, enquanto que em coordenadas generalizadas são analisados os problemas de escoamento sobre o perfil NACA 0012, sobre a parte frontal do VLS, sobre um cone, sobre uma cunha e sobre a região do VLS onde se encontram os boosters, admitindo uma situação bi-dimensional.

Dissertação (mestrado profissional) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Métodos e Gestão em Avaliação, Florianópolis, 2015. / Made available in DSpace on 2016-05-24T17:41:13Z (GMT). No. of bitstreams: 1 338285.pdf: 2513554 bytes, checksum: fdded9a350387a19f94cadf3fa640b4d (MD5) Previous issue date: 2015 / No presente estudo utilizou-se uma modelagem multidimensional do Exame Nacional do Ensino Médio (ENEM), por meio da Teoria da Resposta ao Item multidimensional (TRIM) com o objetivo de melhor compreender o aprendizado do avaliado. O ENEM (1998-2008) era um exame interdisciplinar estruturado por cinco competências expressas por 21 habilidades. Assim, por ser uma avaliação em que não podemos, a priori, considerar unidimensional, realizou-se uma análise da dimensionalidade e interpretação de suas dimensões. Inicialmente foi analisado o conjunto de 63 itens da prova amarela do ENEM 2001 em uma amostra de 10.000 respondentes. Nessa fase foi abordada a dimensionalidade da prova e a escolha do modelo que melhor se ajustava aos dados. Em seguida, foi ajustado um modelo multidimensional da TRI, com cinco dimensões, e foi feita uma relação das competências da prova do ENEM com os fatores, por meio da analise dos itens da prova. Nesta relação ficou evidenciada uma relação mais expressiva das cinco competências com somente três dimensões. Por último, foi feita uma comparação dos avaliados que acertaram 40, 50 e 60 itens na prova, através da analise da porcentagem do número de acerto em cada competência e escores, estimados por meio dos modelos multidimensionais da TRI, em cada uma das cinco dimensões, com a finalidade de interpretar o desempenho desses avaliados.<br> / Abstract : In the present study we used a multi-dimensional modeling of the National Examination of Secondary Education (ENEM), through multidimensional item response theory (MIRT) in order to better understand the learning assessed. The ENEM (1998-2008) was an interdisciplinary examination structured for five competencies expressed by 21 skills. So, being an assessment, we can not, a priori, to consider one-dimensional, there was an analysis of dimensionality and interpretation of its dimensions. Initially we analyzed the set of 63 items Yellow proof of ENEM 2001 on a sample of 10,000 respondents. In this phase it addressed the dimensionality of proof and choosing the model that best fit the data. Then a multidimensional model of TRI was adjusted with five dimensions, and was made a list of ENEM proof competencies with the factors through the analysis of the test items. This relationship was evidenced a more significant relationship of the five competencies with only three dimensions. Finally, a comparison of the assessed was made that hit 40, 50 and 60 items in the race through the analysis of the percentage of the hit number in each jurisdiction and scores, estimated by the multidimensional IRT models in each of the five dimensions in order to interpret the performance of these reviews.

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