This work focuses on the development of a reliable numerical model for investigating the bone-conduction of sound in the human head. The main challenge of the problem is the lack of fundamental knowledge regarding the transmission of acoustic energy through non-airborne pathways to the cochlea. I employed a fully coupled model based on the acoustic/elastic interaction problem with a detailed resolution of the cochlea region and its interface with the skull and the air pathways. The problem was simulated via hp-finite element approximation, employing a hybrid mesh (tetrahedral, prismatic and pyramidal elements) to better capture the geometrical features of the head. The numerical results thus obtained provide an insight into this fundamental, long standing research problem. / text

Hannover, Univ., Diss., 2004.

No description available.

No description available.

Users are often frustrated when a touch screen monitor inaccurately records their touches. Enlarging touch sensitive regions improves touch accuracy, but few specific guidelines are available in the literature. A controlled field experiment determined the effect of target location and visual target size on user accuracy and empirically derived quantitative guidelines for determining touch target size based. on target location. The experiment was conducted in a grocery store using a piezo-electric monitor in a public access kiosk. Participants pressed the screen as target squares appeared one at a time. Visual target size, horizontal viewing location, and screen sector of target were varied. X and Y offset between the target center and the touch location were recorded. Results showed Significant differences caused by target sector in X offsets among columns and in Y offsets among rows, but no differences caused by target size. Results showed that persons tended to touch below the target, with touch distance increasing as the location of the target moved down the screen. To a lesser extent, persons tended to touch toward the sides of the screen. Using collected data for each of nine screen sectors, graphs were prepared showing the relationship between touch target size and expected accuracy under harsh conditions. These empirically derived, quantitative guidelines will help designers plan for the worst case and create screens that decrease user errors and frustration. / Master of Science

This research was part of a program sponsored by the Army Electronics Research and Development Command. The program goals are to develop a generic input/output device based on a 4- x 8-in electroluminescent flat panel display coupled with a touch sensitive input device. The primary purpose of this dissertation was to evaluate the six major manufacturers' implementation of the three most common technologies for touch screens. The evaluation was based on operator performance. The three technologies represented in the research were IR beam matrix switches, conductive membrane switches, and transparent capacitance switches. A secondary goal of the research was to establish a link between measurable hardware parameters of any touch sensitive device (TSO) and operator performance. These parameters were then used to build models of operator performance under a variety of conditions. The primary goal of technology evaluation was approached through two experiments based on two generic types of tasks typical of current and expected TSD applications. These experiments compared six different TSDs from different manufacturers across varying conditions of lighting, viewing angle, and touch target dimensions. The secondary goal of TSD performance modeling was accomplished through careful measurement of many image quality and touch sensing characteristics of the six TSDs and subsequent construction of stepwise linear regression models of user performance. These models were built using the performance data collected in the first part of the evaluation. Results from the performance comparison revealed that across tasks and conditions, one device of the IR beam technology was found to be the best performer. Another device of the same technology was equivalent in reading aspects of performance but inferior with respect to touch inputting performance. This performance difference was hypothesized to be due to differences between these two devices in touch sensor parallax. The linear regression modeling effort resulted in the identification of several hardware parameters which are important to TSD user performance. Additionally, models of performance under specific conditions were developed which accounted for most of the variation observed in the performance data. / Ph. D.

Materiais empregados em polos petroquímicos têm sofrido exigências cada vez mais criteriosas em relação as suas condições de trabalho e desempenho em campo e, atualmente, a liga metálica mais utilizada para a confecção de tubos centrifugados para aplicação nesses locais de trabalho é a liga de aço inoxidável HP modificada com microadições (HPNb-MA). Esses materiais, cuja microestrutura na condição bruta de fundição é composta por uma matriz austenítica com carbonetos de cromo e nióbio nos contornos dos grãos e que apresentam propriedades paramagnéticas em temperatura ambiente, são empregados em polos petroquímicos por apresentarem excelentes propriedades mecânicas em temperaturas elevadas, além de considerável resistência a carburização e perda de massa por oxidação. Visando melhores desempenhos e maiores durabilidades, as microadições são realizadas de maneira intencional e controlada durante o processo de centrifugação. Entre elas, os elementos pertencentes as terras raras têm apresentado resultados satisfatórios em relação a melhorias em propriedades mecânicas em temperatura ambiente e em temperaturas elevadas. O presente trabalho busca padronizar a microadição de ítrio e titânio na liga em estudo, realizando comparações com um material similar cuja composição química se diferencia apenas pela não adição de terras raras durante a confecção dos tubos. Análises comparativas e estatísticas foram realizadas com o intuito de se determinar qual amostra obteria o melhor desempenho em campo. Como parâmetros, foram adotados ensaios de análise química, propriedades mecânicas em temperatura ambiente e temperaturas elevadas, ruptura por fluência, macrografia, microscopia eletrônica de varredura, raios-X, MET, carburização e oxidação. Em paralelo, foi desenvolvido um equipamento capaz de quantificar o nível de carburização dos materiais em estudo em função de alterações das propriedades ferromagnéticas dessas ligas metálicas quando expostas a ambientes carburizantes e com elevadas temperaturas, utilizando para isso, resultados obtidos a partir de simulações laboratoriais e amostras obtidas diretamente de fornos de pirólise. / Materials used in petrochemical poles have undergone increasingly demanding requirements regarding their working conditions and performance in the field. Today, the most used metal alloy for the manufacture of centrifugally cast tubes applied in these work places is the HP stainless steel alloy, modified with micro-addition (HPNb-MA). These materials, which microstructure in as-cast condition is made of an austenitic array of chromium and niobium carbides contouring the grains, exhibit paramagnetic properties at room temperature. They are employed in the petrochemical poles because of its excellent mechanical properties at elevated temperatures, in addition to considerable resistance to carburization and mass loss by oxidation. Aiming for a better performance and longer durability, the micro-addition is carried out in an intentional and controlled way during the centrifugation process. Between them, the elements belonging to rare earths have presented satisfactory results regarding to improvements in its mechanical properties at room temperature and at elevated temperatures. The present work seeks to standardize the micro-addition process of yttrium and titanium in the alloy under study, making comparisons with a similar material which chemical composition differs only by not adding rare earths during the tubes manufacture. Comparative and statistics analysis were carried out with the intent of determining which sample would attain the best performance in the field. Chemical analysis tests, mechanical properties at room temperature and at elevated temperatures, creep rupture, macrography, scanning electron microscopy, X-ray, TEM, carburization and oxidation were adopted as parameters. In parallel, an equipment capable of quantifying the carburization level of the materials under study was developed. These levels are measured in function of changes in the ferromagnetic properties of these metallic alloys when exposed to carburizing and high temperature environments. The equipment makes use of results obtained from laboratory simulations and samples obtained directly from pyrolysis furnaces.

A predição de estruturas de proteínas (Protein Structure Prediction PSP) é um problema computacionalmente complexo. Para tratar esse problema, modelos simplificados de proteínas, como o Modelo HP, têm sido empregados para representar as conformações e Algoritmos Evolutivos (AEs) são utilizados na busca por soluções adequadas para PSP. Entretanto, abordagens utilizando AEs muitas vezes não tratam adequadamente as soluções geradas, prejudicando o desempenho da busca. Neste trabalho, é apresentada uma formulação multiobjetivo para PSP em Modelo HP, de modo a avaliar de forma mais robusta as conformações produzidas combinando uma avaliação baseada no número de contatos hidrofóbicos com a distância entre os monômeros. Foi adotado o Algoritmo Evolutivo Multiobjetivo em Tabelas (AEMT) a fim de otimizar essas métricas. O algoritmo pode adequadamente explorar o espaço de busca com pequeno número de indivíduos. Como consequência, o total de avaliações da função objetivo é significativamente reduzido, gerando um método para PSP utilizando Modelo HP mais rápido e robusto / Protein Structure Prediction (PSP) is a computationally complex problem. To overcome this drawback, simplified models of protein structures, such as the HP Model, together with Evolutionary Algorithms (EAs) have been investigated in order to find appropriate solutions for PSP. EAs with the HP Model have shown interesting results, however, they do not adequately evaluate potential solutions by using only the usual metric of hydrophobic contacts, hamming the performance of the algorithm. In this work, we present a multi-objective approach for PSP using HP Model that performs a better evaluation of the solutions by combining the evaluation based on the number of hydrophobic contacts with the distance among the hydrophobic amino acids. We employ a Multi-objective Evolutionary Algorithm based on Sub-population Tables (MEAT) to deal with these two metrics. MEAT can adequately explore the search space with relatively low number of individuals. As a consequence, the total assessments of the objective function is significantly reduced generating a method for PSP using HP Model that is faster and more robust

Dans cette thèse, nous nous intéressons à l’amélioration des performances numériques dela méthode Galerkin Discontinu en Domaine Temporel (GDDT), afin de valoriser son emploi industrielpour des problèmes de propagation d’ondes électromagnétiques. Pour ce faire, nous cherchons à réduire lenombre d’éléments des maillages utilisés en appliquant une stratégie de h-déraffinement/p-enrichissement.Dans un premier temps, nous montrons que si ce type de stratégie permet d’améliorer significativementl’efficacité numérique des résolutions dans un cadre conforme, son extension aux maillages non-conformespeut s’accompagner de contre-performances rédhibitoires limitant fortement leur intérêt pratique. Aprèsavoir identifié que ces dernières sont causées par le traitement des termes de flux non-conformes, nousproposons une méthode originale de condensation afin de retrouver des performances avantageuses. Cellecise base sur une redéfinition des flux non-conformes à partir d’un opérateur de reconstruction de traces,permettant de recréer une conformité d’espaces, et d’un produit scalaire condensé, assurant un calculapproché efficace. La stabilité et la consistance du schéma GDDT ainsi défini sont établies sous certainesconditions portant sur ces deux quantités. Dans un deuxième temps, nous détaillons la construction desopérateurs de trace et des produits scalaires associés. Nous proposons alors des flux condensés pourplusieurs configurations non-conformes, et validons numériquement la convergence du schéma GDDT résultant.Puis, nous cherchons à concevoir un algorithme de h-déraffinement/p-enrichissement automatisé,dans le but de générer des maillages hp minimisant les coûts de calcul du schéma. Ce processus est traduitsous la forme d’un problème d’optimisation combinatoire sous plusieurs contraintes de natures trèsdiverses. Nous présentons alors un algorithme de post-maillage basé sur un parcours efficace de l’arbrede recherche des configurations admissibles, associé à un processus de déraffinement hiérarchique. Enfin,nous mettons en œuvre la chaîne de calcul développée sur plusieurs cas-tests d’intérêt industriel, etévaluons son apport en termes de performances numériques. / This thesis is devoted to improving the numerical efficiency of the Discontinuous Galerkinin Time Domain (DGDT) method, in order to enhance its suitability for industrial use. One can noticethat, in an hp-conforming context, increasing correlatively the approximation order and the mesh sizeis a powerful strategy to reduce numerical costs. However, in complex geometries, the mesh can beconstrainted by the presence of small-scale inner elements, leading to hp-nonconforming configurationswith hanging nodes. The first issue we are dealing with is related to the nonconforming fluxes involvedin these configurations, whose high computational costs can deter the use of hp-coarsening strategies.In order to recover a satisfactory performance level, an original flux-lumping technique is set up. Thistechnique relies on recasting hybrid fluxes into conforming ones, and is performed by introducing twoingredients : a reconstruction operator designed to map traces from each side of a nonconforming interfaceinto the same functional space, and a lumped scalar product granting efficient integral computations.The resulting DGTD scheme is then proved to be stable and consistent, under some assumptions on thelatter two elements. Subsequently, we develop a lumped flux construction routine, and show numericalconvergence results on basic hybrid configurations. In a second part, we implement an automated strategyaiming at generating efficient hp-nonconforming meshes, well-suited to the previous DGDT scheme. To doso, a post-meshing process is formalized into a constrained optimization problem. We then put forward aheuristic hp-coarsening algorithm, based on a hierarchical coarsening approach coupled with an efficientsearch over the feasible configuration tree. Lastly, we present several numerical examples related toelectromagnetic wave propagation problems, and evaluate computational cost improvements.

Submitted by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2015-06-02T12:16:09Z No. of bitstreams: 1 arquivototal.pdf: 1083776 bytes, checksum: 399c5b22353566747d56756453686cc3 (MD5) / Approved for entry into archive by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2015-06-02T12:55:19Z (GMT) No. of bitstreams: 1 arquivototal.pdf: 1083776 bytes, checksum: 399c5b22353566747d56756453686cc3 (MD5) / Made available in DSpace on 2015-06-02T12:55:19Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1083776 bytes, checksum: 399c5b22353566747d56756453686cc3 (MD5) Previous issue date: 2014-08-26 / This research has as object of study the teaching of Financial Mathematics, with the aid of a tool: the Financial Calculator HP 12C, preparing citizens able to manage their own budgets and the labor market. Preliminary concepts concerning the theme are presented, followed by examples in context, pointing out the main factors that facilitate the understanding of each content. Being approached through practical applications, which makes learning easier, and increases motivation and students' interest. / Este trabalho de pesquisa tem como escopo o ensino da Matemática Financeira, com o auxílio de uma ferramenta: a calculadora financeira HP 12C, preparando cidadãos capazes de administrar suas próprias finanças e para o mercado de trabalho. Apresenta conceitos preliminares ao tema, seguido de exemplos contextualizados, apontando os principais fatores, que facilitam a compreensão em cada conteúdo. Sendo tratado através de aplicações práticas, que facilita a aprendizagem, motivação e interesse do aluno.