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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.
211

Biomechanical Modeling of Manual Wheelchair Propulsion:Force Capability Investigation for Improved Clinical Fitting Procedures

Koehler, Amy 25 September 2017 (has links)
No description available.
212

Exploring the Time-Based Resource-Sharing Model of Working Memory Through Computational Modeling

Glavan, Joseph 19 June 2017 (has links)
No description available.
213

Structural Analysis of Soft-Hard Material Interface in an Ant Neck Joint

Owino, Vivianne January 2013 (has links)
No description available.
214

Tumor priming enhances particle delivery to and transport in solid tumors

Lu, Dan 14 July 2006 (has links)
No description available.
215

Design and Synthesis of Metal Oxide Nanomaterials and Study of Their Electronic Properties for Energy Conversion via Dye-sensitized Solar Cells

Natu, Gayatri 28 August 2012 (has links)
No description available.
216

Time in Mind: Understanding the Role of Episodic Future Thinking in Intertemporal Choice

Kinley, Isaac January 2024 (has links)
Humans and other animals systematically discount the value of future rewards as a function of their delay, and individual differences in the steepness of this ``delay discounting'' are predictive of a range of important real-world outcomes. Episodic future thinking, the mental simulation of episodes in the personal future, is one means by which to curb delay discounting. This thesis seeks to contribute to our understanding of how this effect occurs. The account that predominates in the literature is that episodic future thinking simulates the experience of future rewards, enabling their undiscounted value to be appreciated in the present. This thesis takes this account as a starting point, formalizing it in a mathematical model and carrying out several experimental studies to test its predictions. We find that key predictions are not borne out and develop an alternative account in which simulated experience plays a less central role. / Thesis / Doctor of Philosophy (PhD) / Pursuing our goals for the future usually means sacrificing immediate gratification, yet we often make decisions that are not in our best interest over the long term. This is because we assign lower subjective value to future rewards the further they are from the present. Individuals differ in how much they devalue future rewards, and these differences are related to many real-world outcomes. Our tendency to devalue future rewards is reduced when we vividly imagine the future in a process called ``episodic future thinking,'' and this thesis seeks to understand how this effect occurs. The most obvious explanation would seem to be that episodic future thinking ``simulates'' the experience of future rewards and allows us to recognize their value in the present. However, using results from several experimental studies, I argue that this may not be the best explanation after all, and I develop an alternative.
217

Análisis comparativo de estabilidad de taludes mediante las ecuaciones de equilibrio límite: método de morgenstern-price, spencer, sarma

Becerra Carrillo, Edgar Alonso January 2024 (has links)
Esta investigación tiene por finalidad Comparar las ecuaciones de equilibrio limite Morgenstern-Price, Spencer, Sarma aplicado a la estabilidad del talud del cerro Chalpón, distrito de Motupe y buscar una solución de estabilización del talud, el factor de seguridad del talud se obtendrá mediante el modelado en el software Slide, los datos que el software necesita son el perfil topográfico del talud, la cohesión, ángulo de fricción y peso específico de los materiales que lo conforman, para encontrar estos datos se debe hacer algunos ensayos de laboratorio cómo el ensayo de corte, el ensayo de peso específico y el ensayo de compresión de la roca. Se clasifico el macizo rocoso mediante índices de Bieniawski (R.M.R) con índices desde 47% hasta 63% mientras índice de calidad “Q” (Q de Barton) oscilo entre 0.325 a 2.375. Se elaboró 6 perfiles y cada perfil con 3 escenarios, de los cuales 4 perfiles tuvieron un factor de seguridad menor a 1.3, y se optó por las soluciones de estabilidad para el perfil “B” usar material de relleno (afirmado), para el perfil “C” se consideró 7 micropilotes de 5 m con diámetro de 13 cm distribuidos cada 1.5 m transversal y en el eje longitudinal estás distribuido cada 1 m, para perfil de “D” también necesita un muro de contención, y se debe rellenar como se muestra en el detalle con afirmado de las mismas características que el perfil C, para el perfil E se necesita 9 micropilotes de 13 cm de diámetro y 4 m de longitud y en el eje longitudinal estás distribuido cada 1 m, todos los micro pilotes serán clavados perpendicular al terreno. La solución beneficiará a que no haya deslizamientos de rocas ni de terrenos, lo que hará mantener su forma del cerro, evitando así el movimiento de tierra o escombros debido a deslizamientos. / The purpose of this research is to compare the equations of limit equilibrium Morgenstern-Price, Spencer, Sarma applied to the stability of the slope of Chalpon hill, district of Motupe and to look for a solution of slope stabilization, the safety factor of the slope will be obtained by modeling in the Slide software, The data that the software needs are the topographic profile of the slope, the cohesion, friction angle and specific weight of the materials that conform it, to find these data some laboratory tests must be done how the shear test, the specific weight test and the rock compression test. The rock massif was classified by means of Bieniawski indexes (R.M.R) with indexes from 47% to 63% while quality index "Q" (Barton's Q) ranged between 0.325 to 2.375. Six profiles were elaborated and each profile with three scenarios, of which four profiles had a safety factor lower than 1.3, and stability solutions were chosen for profile "B" using backfill material, for profile "C" 7 micropiles of 5 m with a diameter of 13 cm were considered, distributed every 1.5 m transversely and in the axis of the profile "C". 5 m transverse and in the longitudinal axis you are distributed every 1 m, for profile "D" also needs a retaining wall, and should be filled as shown in the detail with affirmed of the same characteristics as profile C, for profile E is needed 9 micropiles of 13 cm in diameter and 4 m in length and in the longitudinal axis you are distributed every 1 m, all micro piles will be nailed perpendicular to the ground. The solution will benefit that there will be no sliding of rocks or land, which will maintain the shape of the hill, thus avoiding the movement of earth or debris due to landslides.
218

An in-situ visualization approach for parallel coupling and steering of simulations through distributed shared memory files / Une approche de visualisation in-situ pour le couplage parallèle et le pilotage de simulations à travers des fichiers en mémoire distribuée partagée

Soumagne, Jérôme 14 December 2012 (has links)
Les codes de simulation devenant plus performants et plus interactifs, il est important de suivre l'avancement d'une simulation in-situ, en réalisant non seulement la visualisation mais aussi l'analyse des données en même temps qu'elles sont générées. Suivre l'avancement ou réaliser le post-traitement des données de simulation in-situ présente un avantage évident par rapport à l'approche conventionnelle consistant à sauvegarder—et à recharger—à partir d'un système de fichiers; le temps et l'espace pris pour écrire et ensuite lire les données à partir du disque est un goulet d'étranglement significatif pour la simulation et les étapes consécutives de post-traitement. Par ailleurs, la simulation peut être arrêtée, modifiée, ou potentiellement pilotée, conservant ainsi les ressources CPU.Nous présentons dans cette thèse une approche de couplage faible qui permet à une simulation de transférer des données vers un serveur de visualisation via l'utilisation de fichiers en mémoire. Nous montrons dans cette étude comment l'interface, implémentée au-dessus d'un format hiérarchique de données (HDF5), nous permet de réduire efficacement le goulet d'étranglement introduit par les I/Os en utilisant des stratégies efficaces de communication et de configuration des données. Pour le pilotage, nous présentons une interface qui permet non seulement la modification de simples paramètres, mais également le remaillage complet de grilles ou des opérations impliquant la régénérationde grandeurs numériques sur le domaine entier de calcul d'être effectués. Cette approche, testée et validée sur deux cas-tests industriels, est suffisamment générique pour qu'aucune connaissance particulière du modèle de données sous-jacent ne soit requise. / As simulation codes become more powerful and more interactive, it is increasingly desirable to monitor a simulation in-situ, performing not only visualization but also analysis of the incoming data as it is generated. Monitoring or post-processing simulation data in-situ has obvious advantage over the conventional approach of saving to—and reloading data from—the file system; the time and space it takes to write and then read the data from disk is a significant bottleneck for both the simulation and subsequent post-processing steps. Furthermore, the simulation may be stopped, modified, or potentially steered, thus conserving CPU resources. We present in this thesis a loosely coupled approach that enables a simulation to transfer data to a visualization server via the use of in-memory files. We show in this study how the interface, implemented on top of a widely used hierarchical data format (HDF5), allows us to efficiently decrease the I/O bottleneck by using efficient communication and data mapping strategies. For steering, we present an interface that allows not only simple parameter changes but also complete re-meshing of grids or operations involving regeneration of field values over the entire computational domain to be carried out. This approach, tested and validated on two industrial test cases, is generic enough so that no particular knowledge of the underlying model is required.
219

Compartimentação de edifí­cios para a segurança contra incêndio. / Building compartmentation for the fire safety.

Andrade, Thiago Menezes de 12 June 2018 (has links)
Os métodos para se projetar um edifício com segurança adequada para a situação de incêndio são pouco estudados e aplicados no Brasil. Essa falta de estudo é ainda mais visível quando nos deparamos com o assunto compartimentação, tópico pouco desenvolvido e ainda não normatizado pela ABNT. A compartimentação, especialmente a vertical, é fundamental para a segurança à vida, pois minimiza a propagação do incêndio entre pavimentos de edifícios. Para validar os procedimentos normatizados de dimensionamento de estruturas em situação de incêndio é necessário considerar que as edificações são compartimentadas. Atualmente as exigências sobre compartimentação são apresentadas apenas em Instruções Técnicas do Corpo de Bombeiros, variando de estado para estado. Neste trabalho é apresentado um estudo sobre a compartimentação, uma análise de sua influência na segurança contra incêndio das edificações e a comparação da visão do assunto em países de quatro continentes distintos. Após um estudo comparativo entre a visão e normatização do Brasil, Portugal, Inglaterra, Hong Kong e Estados Unidos foram realizadas simulações computacionais com base na teoria dos volumes finitos e da fluidodinâmica computacional de forma a se tentar verificar de forma mais aprofundada a influência das exigências de compartimentação na real propagação de um incêndio. Por fim, o principal foco deste trabalho é demonstrar que é possível utilizar a Dinâmica dos Fluidos Computacionais (CFD) de maneira a auxiliar o estudo do incêndio, e possibilitar uma análise mais aprofundada do assunto. / Methods for designing a building with adequate fire safety are poorly studied and applied in Brazil. This lack of study is even more present in the compartmentation subject, much-undeveloped topic and not yet standardized by ABNT. The compartmentation, especially the vertical, is critical to life safety, since it minimizes the spread of fire between building floors, and to validate the standardized procedures for structures in fire situation, because an important hypothesis of design methods is the vertical compartmentation. Currently the requirements of compartmentation are only present in the Technical Instructions of the States Fire Department, varying from state to state. This paper presents a study on compartmentation, its influence on the fire safety of buildings and a comparison of the vision of some countries of four different continents on this subject. After a comparative study of the vision and standardization between countries such as Brazil, Portugal, England, Hong Kong and the United States, computer simulation based on the theory of the finite volumes and computational fluid dynamics were carried out in order to try to check thoroughly the influence of compartmentation requirements in a real fire spread. Ultimately, the main focus of this work is to demonstrate that the Computational Fluid Dynamics (CFD) can be used in order to assist the study of fire, in order to allow a more in-depth analysis of the subject.
220

Teores de água e solutos no solo: desempenho e sensibilidade do modelo Hydrus-1D / Water and solutes contents in soil: performance and sensitivity of Hydrus-1D model

Pinho, Roque Emmanuel da Costa de 15 January 2010 (has links)
A preocupação com o destino de produtos químicos e água, aplicados ao solo, tem motivado vários pesquisadores a desenvolverem e aplicarem modelos teóricos, objetivando descrever os processos físicos envolvidos no transporte desses produtos no perfil do solo. Nesse sentido, a presente pesquisa teve como objetivo a aplicação do modelo Hydrus-1D para simulação do movimento da água e dos íons nitrato e potássio, em condições de laboratório, utilizando-se para tal colunas segmentadas preenchidas com dois tipos de solo não-saturado (Latossolo Vermelho Amarelo e Nitossolo Vermelho), bem como avaliar o desempenho e sensibilidade do referido modelo. Para a obtenção dos parâmetros de transporte de cada soluto, foram elaboradas as curvas de distribuição de efluentes (Breakthrough Curves BTC). Os parâmetros de transporte obtidos e as condições de contorno de cada ensaio foram inseridos no modelo Hydrus- 1D para realização das simulações. O desempenho do modelo foi avaliado com base nos parâmetros estatísticos: erro máximo, erro absoluto médio, raiz quadrada do erro médio normalizado, coeficiente de massa residual, coeficiente de determinação, eficiência e índice de concordância de Willmott. A sensibilidade do modelo foi avaliada conforme o método proposto por McCuen e Snyder (1986) e a análise foi aplicada aos parâmetros: fluxo de entrada, condutividade hidráulica do solo saturado, teor de água na saturação, alfa e n (parâmetros de ajuste da curva de retenção), coeficiente de distribuição e dispersividade. Os resultados experimentais mostraram que o deslocamento do íon nitrato acompanhou a frente de molhamento e em relação ao potássio, observou-se uma maior retenção nas camadas superficiais da coluna de solo, para ambos os solos. Pôde-se concluir que o modelo Hydrus-1D foi eficiente para simulações de deslocamento de potássio e água para ambos os solos estudados e mediante a utilização do modelo de equilíbrio para o transporte de solutos no solo, o modelo Hydrus-1D não foi eficiente para simular o deslocamento de nitrato, para ambos os solos. Os procedimentos experimentais para estimativa de parâmetros de transporte, como as curvas de distribuição de efluentes, foram suficientes para descrever a movimentação de potássio no solo, gerando informações de entrada precisas para os modelos de simulação. Para a simulação do deslocamento do íon nitrato, concluiu-se que o modelo Hydrus-1D requer um processo experimental mais detalhado, sendo necessária a estimativa de um maior número de parâmetros de transporte. Em relação à análise de sensibilidade, ao simular os teores de potássio e água no solo, o modelo apresentou maior sensibilidade aos parâmetros teor de água na saturação e fluxo de entrada da solução. Tais parâmetros, portanto, precisam ser determinados com maior precisão. Houve baixa sensibilidade aos parâmetros condutividade hidráulica do solo saturado e dispersividade, para ambos os solos estudados. / The concern about the fate of chemical products and water, applied to the soil, has been motivating several researchers to develop and apply theoretical models, aiming to describe the physical processes involved in the transport of those products in soil profile. The present research had as objective the application of the model Hydrus- 1D for water and solute (nitrate and potassium) simulation profile, in laboratory conditions, using soil columns filled with two types of unsaturated soil (Oxisol (Haplustox) and Hapludox), as well to evaluate the acting and sensitivity of the model. The transport parameters were obtained for each solute by breakthrough curves (BTCs). The transport parameters obtained and the boundary conditions were inserted in the Hydrus-1D model to realize the simulations. The acting of the Hydrus-1D model was evaluated using the statistical indicators: maximum error, mean absolute error, normalized root mean-square error, coefficient of residual mass, determination coefficient, efficiency and Willmott concordance index. The model sensitivity was evaluated by the method proposed by McCuen and Snyder (1986) and applied to the parameters: input flow, soil saturated hydraulic conductivity, water content (saturation point), alpha and n (soil water retention curve parameters), distribution coefficient and dispersivity. The obtained results, experimentally, showed the nitrate displacement following the wetting front and, in relation to the potassium ion, a larger retention was observed at the superficial soil columns layers. Therefore, was possible to conclude that Hydrus-1D model was efficient for both water and potassium displacement simulations, for both studied soils and by the balance model for solute transport in soil, the Hydrus- 1D model was not efficient to simulate the nitrate displacement in both soils. The experimental procedures to estimate transport parameters, by the BTCs, were enough to describe the potassium movement in soil, generating input information necessary to the model simulation. To the simulation of the nitrate displacement, was possible to conclude that the model Hydrus-1D requests a more detailed experimental process, being necessary the estimate of a larger number of transport parameters. In relation to the sensitivity analysis of the Hydrus-1D model, when simulated the content of potassium and water at the soil columns, was observed that the model shows more sensitivity about to the parameters: water content (saturation point) and input flow. This parameters need to be estimated with more precision. There was a low sensitivity to the parameters soil saturated hydraulic conductivity and dispersivity for both studied soils.

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