Le rendu en temps réel repose sur des compromis entre la performance et le réalisme. Un de ces compromis est de représenter des matériaux plus minces tels que les tissus comme étant infiniment minces pour économiser mémoire et temps de rendu. Par contre, cette perte de dimension prive la surface de propriétés essentielles à certains effets visuels. Dans ce mémoire, nous présentons une méthode pour simuler les effets de l’épaisseur sur des surfaces semi-transparentes en utilisant des textures composées de texels opaques et transparents. Nous analysons les trous formés par les texels transparents et nous conservons de l’information sur les contours des trous dans une structure hiérarchique compatible avec la méthode de filtrage de textures par MIP map. Nous dérivons des équations représentant la proportion de lumière passant dans un trou avec des murs intérieurs en fonction de l’angle incident des rayons de lumière. Nous combinons ces équations avec l’information conservée pour calculer un terme de transparence à différents niveaux de détail en temps réel. / Real-time rendering is built upon compromises between performance and realism. One such compromise is to represent thinner materials like textile as infinitely thin in order to save on memory and rendering time. However, this loss of dimension robs the surface of properties key to some visual effects. In this thesis, we present a method to simulate the effects of thickness on semi-transparent surfaces using textures consisting of opaque and transparent texels. We analyze holes formed by transparent texels and store information about the contours of the holes in a hierarchical structure compatible with the filtering method of MIP mapping. We derive equations representing the proportion of light passing through a hole as a function of the incident angle of light. The proportions of texel top, texel side wall, and hole are computed accurately. We combine these equations with the information stored to compute a transparency term at different levels of detail in real time.

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[pt] Este trabalho teve como objetivo propor um sistema construtivo misto eficiente e econômico para edificações. Foram concebidos dois detalhes de ligação semi-rígida mista, o primeiro para colunas de extremidade, e o segundo para colunas intermediárias, executados no eixo de maior inércia da coluna. A ligação de extremidade motivou o desenvolvimento de um novo elemento de ligação: o conector T-rib. Sua principal função é transmitir a resultante das barras de armadura de flexão nas regiões de momento negativo para a mesa das colunas de extremidade. O presente trabalho também envolveu uma investigação de dois modelos para ligações semi-rígidas: o modelo analítico simplificado de Kishi-Chen, [CHEN93], e o modelo mecânico do Anexo J do EUROCODE3, [EURO98], gerando duas alternativas para modelos semi-rígidos mistos. O primeiro modelo de cálculo, desenvolvido a partir do modelo de Kishi e Chen, [CHEN93], permite o cálculo dos dois detalhes de ligação citados anteriormente. O segundo modelo proposto foi concebido a partir da incorporação das contribuições do conector T-rib, das cantoneiras de alma e das barras de armadura existentes nos dois detalhes de ligação citados anteriormente, já que o modelo original do EUROCODE3, não considera estas componentes. Uma calibração dos modelos propostos foi executada a partir de uma comparação com valores obtidos experimentalmente no presente trabalho. Uma solução alternativa para conectores de cisalhamento de vigas mistas de concreto e aço também foi desenvolvida. Esta solução consistiu na adaptação do conector de cisalhamento perfobond rib utilizado em pontes mistas para uso em edificações correntes. Esta investigação resultou na criação de um novo layout para este tipo de ensaio. Este novo ensaio permitiu a determinar a contribuição dos cilindros de concreto e barras de armadura nos furos do conector perfobond rib e aferiu, pela primeira vez na literatura, a fórmula de resistência ao cisalhamento para este conector proposta por Oguejiofor e Hosain, [OGUE94]. Para caracterizar os possíveis estados de ruína do conector T-rib uma série de seis ensaios foi executada. Esta etapa de trabalho compreendeu o desenvolvimento de um novo tipo de ensaio de arrancamento projetado especialmente para esta investigação. Para avaliar o desempenho global do sistema construtivo proposto foi construído e ensaiado um pórtico plano semi-rígido misto em escala real, executado de modo a permitir a aferição do comportamento real das ligações, do comportamento do conjunto das viga-mistas e das vigas- colunas da estrutura. Este ensaio permitiu a determinação de curva carga versus. Rotação, uma estimativa dos esforços máximos de flexão nas ligações, etc. / [en] This work focused on the development of an efficient and economic composite building system. This was accomplished by the conception of two new composite major axis connection details for external and intermediate columns. The external column connection detail motivated the creation of a new connection element: the T-rib connector. The main purpose of this element is to transmit the reinforcement bars forces directly to the external columns in negative moment regions The present study also comprehended an nvestigation of two semi-rigid connections design models:the simplified analytical model of Kishi-Chen, [CHEN93], and the Eurocode 3 mechanical model,[EURO98], leading to further developments in both structural models. The first proposal extends the Kishi-Chen model, [CHEN93], for the external and intermediate columns connections investigated in this work. The second proposal incorporated the contributions of the T-rib connector, the web angles and the reinforcement bars on the EUROCODE3 model, since they were not originally taken into account. Both model were calibrated against the experimental results produced in the present investigation. An alternative solution for composite beams shear connectors was also developed. This solution consisted of an adaptation of the perfobond rib shear connector, generally used in composite bridges, to residential or commercial building construction. This investigation resulted in the development of a new test layout for the required experiments. These experiments enabled the determination of the individual contribution of the concrete dowels and reinforcement bars used in the perfobond rib connector holes. As far as it is known, these tests enable the calibration and evaluation V of each individual term of the perfobond rib resistance formula proposed by Oguejiofor and Hosain, [OGUE94]. A set of six tests was also made to characterise the T-Rib connector ultimate limit states. This procedure also required the development of a new pullout test procedure and layout especially designed for this purpose. To evaluate the global performance of the proposed building system a full-scale composite semi-rigid portal frame was built and tested up to collapse. The experimental programme provided information on real structural behaviour where the influence of connections, beam as beam column behaviour ads second order efectswere full investigated. This experimental research enabled the determination of: load versus rotation curves, an estimation of the maximum connection s bending forces, etc. / [es] Este trabajo tiene como objetivo proponer un sistema constructivo mixto eficiente y económico para edificaciones. Fueron concebidos dos detalles de llamada semi-rígida-mixta, el primero para columnas de extremidad, y el segundo para columnas intermediárias, ejecutados en el eje de mayor inercia de la columna. La llamada de extremidad motivó el desarrollo de un nuevo elemento de llamada: el conector T rib. Su principal función es transmitir la resultante de las barras de armadura de flexión en las regiones de momento negativo para la mesa de las columnas de extremidad. Este trabajo también investiga dos modelos para conexiones semi rígidas: el modelo analítico simplificado de Kishi Chen, [CHEN93], y el modelo mecánico del Anexo J del EUROCODE3, [EURO98], generando dos alternativas para modelos semi rígidos mixtos. El primer modelo de cálculo, desarrollado la partir del modelo de Kishi y Chen, [CHEN93], permite el cálculo de los dos detalles de llamada citados anteriormente. El segundo modelo propuesto fue concebido a partir de la incorporación de las contribuciones del conector T rib, de las esquineras de alma y de las barras de armadura existentes en los dos detalles de llamada citados anteriormente, ya que el modelo original del EUROCODE3, no considera estas componentes. Los modelos propuestos fueron calibrados a partir de una comparación con valores obtenidos experimentalmente en el presente trabajo. Una solución alternativa para conectores de cisallamento de vigas mixtas de concreto y acero también fue desarrollada. Esta solución consistió en la adaptación del conector de cisallamento perfobond rib utilizado en puentes mixtas para uso en edificaciones corrientes. Esta investigación tuvo como resultado la creación de un nuevo layout para este tipo de ensayo. Este nuevo ensayo permitio determinar la contribución de los cilindros de concreto y barras de armadura en las perforaciones del conector perfobond rib y ajustó, por primera vez en la literatura, la fórmula de resistencia al cisallamento para este conector propuesta por Oguejiofor y Hosain, [OGUE94]. Para caracterizar los posibles estados de ruina del conector T rib, se ejecutó una série de seis ensayos. Esta etapa del trabajo comprendió el desarrollo de un nuevo tipo de ensayo de arranque proyectado especialmente para esta investigación. Para evaluar el desempeño global del sistema constructivo propuesto, fue construido un pórtico plano semirígido mixto en escala real, ejecutado de tal modo que permita el ajuste del comportamiento real de las conexiones, del comportamiento del conjunto de las viga mixtas y de las vigas columnas de la extructura. Este ensayo permitió la determinación de curva carga versus Rotación, una estimativa de los esfuerzos máximos de flexión en las conexiones, etc.

<p dir="ltr">Traditional methods of behavior classification on videos of mice often rely on manually annotated datasets, which can be labor-intensive and resource-demanding to create. This research aims to address the challenges of behavior classification in mouse studies by leveraging an algorithmic framework employing self-supervised learning techniques capable of analyzing unlabeled datasets. This research seeks to develop a novel approach that eliminates the need for extensive manual annotation, making behavioral analysis more accessible and cost-effective for researchers, especially those in laboratories with limited access to annotated datasets.</p>

För att öka välmående och effektiviteten i ett företags arbete är det viktigt att anställda har en god ergonomi. Ett sätt att åstadkomma detta är att göra en ergonomistudie där fokus ligger på att analysera rörelser som utövas och bidra med lösningar som underlättar arbetet. Uppackningen av inhalator komponenter i luftslussar på AstraZeneca Site Respiratory sker för närvarande helt manuellt. Vilket är en bidragande orsak till skador i axlar, rygg, nacke, handleder och fingrar hos flera anställda. Syftet är att analysera olika semi-automatiserade hjälpmedel som underlättar arbetsmomentet ergonomiskt. För att få en klar syn över problemet har semistrukturerade intervjuer och observationer gjorts på AstraZeneca tillsammans med en genomgående litteraturstudie för att finna tidigare implementationsmetoder i liknande studier. Dessa intervjuer och litterära rapporter har använts för att ta fram ett svar på rapportens frågeställningar: (1) Vilka hjälpmedel finns det för att underlätta uppackning med tunga lyft och drag? (2) Vilka hjälpmedel för uppackning kan ergonomiskt avlasta personalen? Fyra olika hjälpmedel togs fram med metoden. I resultatet presenterades en vakuumlyftare, cobot, ett invändigt plastmembran och en säkerhetskniv. I slutsatsen framgick det att hjälpmedlen ergonomiskt kan avlasta personalen och förebygga olika typer av skador. Genom fortsatta studier av problemet kan en helautomatiserad lösning analyseras. / To enhance well-being and efficiency in a company's operations, it is essential for employees to have good ergonomics. One way to achieve this is to do an ergonomics study where the focus is on analyzing the movements that are performed and contributing solutions that make work easier. Currently, the unpacking of inhaler components in airlocks at AstraZeneca Site Respiratory is done entirely manually. This is a contributing factor to injuries in the shoulders, back, neck, wrists, and fingers of several employees. The aim is to analyze various semi-automated aids that ergonomically ease the task. To gain a clear understanding of the problem, semi-structured interviews and observations were conducted at AstraZeneca, along with a comprehensive literature review to find previous implementation methods in similar studies. These interviews and literary reports have been used to answer the report’s research questions:(1) What aids are there to facilitate unpacking with heavy lifting and pulling?(2) What unpacking aids can ergonomically relieve the staff?Four different aids were developed using the method. The results presented a vacuum lifter, cobot, an internal plastic membrane, and a safety knife. The conclusion indicated that these aids can ergonomically relieve the staff and prevent various types of injuries. Through continued studies of the problem, a fully automated solution can be analyzed.

Two different sets of problems are addressed in this thesis. The first one is on partially observed semi-Markov Games (POSMG) and the second one is on semi-Markov modulated financial market model. In this thesis we study a partially observable semi-Markov game in the infinite time horizon. The study of a partially observable game (POG) involves three major steps: (i) construct an equivalent completely observable game (COG), (ii) establish the equivalence between POG and COG by showing that if COG admits an equilibrium, POG does so, (iii) study the equilibrium of COG and find the corresponding equilibrium of original partially observable problem. In case of infinite time horizon game problem there are two different payoff criteria. These are discounted payoff criterion and average payoff criterion. At first a partially observable semi-Markov decision process on general state space with discounted cost criterion is studied. An optimal policy is shown to exist by considering a Shapley’s equation for the corresponding completely observable model. Next the discounted payoff problem is studied for two-person zero-sum case. A saddle point equilibrium is shown to exist for this case. Then the variable sum game is investigated. For this case the Nash equilibrium strategy is obtained in Markov class under suitable assumption. Next the POSMG problem on countable state space is addressed for average payoff criterion. It is well known that under this criterion the game problem do not have a solution in general. To ensure a solution one needs some kind of ergodicity of the transition kernel. We find an appropriate ergodicity of partially observed model which in turn induces a geometric ergodicity to the equivalent model. Using this we establish a solution of the corresponding average payoff optimality equation (APOE). Thus the value and a saddle point equilibrium is obtained for the original partially observable model. A value iteration scheme is also developed to find out the average value of the game. Next we study the financial market model whose key parameters are modulated by semi-Markov processes. Two different problems are addressed under this market assumption. In the first one we show that this market is incomplete. In such an incomplete market we find the locally risk minimizing prices of exotic options in the Follmer Schweizer framework. In this model the stock prices are no more Markov. Generally stock price process is modeled as Markov process because otherwise one may not get a pde representation of price of a contingent claim. To overcome this difficulty we find an appropriate Markov process which includes the stock price as a component and then find its infinitesimal generator. Using Feynman-Kac formula we obtain a system of non-local partial differential equations satisfied by the option price functions in the mildsense. .Next this system is shown to have a classical solution for given initial or boundary conditions. Then this solution is used to have a F¨ollmer Schweizer decomposition of option price. Thus we obtain the locally risk minimizing prices of different options. Furthermore we obtain an integral equation satisfied by the unique solution of this system. This enable us to compute the price of a contingent claim and find the risk minimizing hedging strategy numerically. Further we develop an efficient and stable numerical method to compute the prices. Beside this work on derivative pricing, the portfolio optimization problem in semi-Markov modulated market is also studied in the thesis. We find the optimal portfolio selections by optimizing expected utility of terminal wealth. We also obtain the optimal portfolio selections under risk sensitive criterion for both finite and infinite time horizon.

Dans un contexte de test multiple, nous considérons un modèle de mélange semi-paramétrique avec deux composantes. Une composante est supposée connue et correspond à la distribution des p-valeurs sous hypothèse nulle avec probabilité a priori p. L'autre composante f est nonparamétrique et représente la distribution des p-valeurs sous l'hypothèse alternative. Le problème d'estimer les paramètres p et f du modèle apparaît dans les procédures de contrôle du taux de faux positifs (``false discovery rate'' ou FDR). Dans la première partie de cette dissertation, nous étudions l'estimation de la proportion p. Nous discutons de résultats d'efficacité asymptotique et établissons que deux cas différents arrivent suivant que f s'annule ou non surtout un intervalle non-vide. Dans le premier cas (annulation surtout un intervalle), nous présentons des estimateurs qui convergent \`{a} la vitesse paramétrique, calculons la variance asymptotique optimale et conjecturons qu'aucun estimateur n'est asymptotiquement efficace (i.e atteint la variance asymptotique optimale). Dans le deuxième cas, nous prouvons que le risque quadratique de n'importe quel estimateur ne converge pas à la vitesse paramétrique. Dans la deuxième partie de la dissertation, nous nous concentrons sur l'estimation de la composante inconnue nonparamétrique f dans le mélange, en comptant sur un estimateur préliminaire de p. Nous proposons et étudions les propriétés asymptotiques de deux estimateurs différents pour cette composante inconnue. Le premier estimateur est un estimateur à noyau avec poids aléatoires. Nous établissons une borne supérieure pour son risque quadratique ponctuel, en montrant une vitesse de convergence nonparamétrique classique sur une classe de Holder. Le deuxième estimateur est un estimateur du maximum de vraisemblance régularisée. Il est calculé par un algorithme itératif, pour lequel nous établissons une propriété de décroissance d'un critère. De plus, ces estimateurs sont utilisés dans une procédure de test multiple pour estimer le taux local de faux positifs (``local false discovery rate'' ou lfdr). / In a multiple testing context, we consider a semiparametric mixture model with two components. One component is assumed to be known and corresponds to the distribution of p-values under the null hypothesis with prior probability p. The other component f is nonparametric and stands for the distribution under the alternative hypothesis. The problem of estimating the parameters p and f of the model appears from the false discovery rate control procedures. In the first part of this dissertation, we study the estimation of the proportion p. We discuss asymptotic efficiency results and establish that two different cases occur whether f vanishes on a non-empty interval or not. In the first case, we exhibit estimators converging at parametric rate, compute the optimal asymptotic variance and conjecture that no estimator is asymptotically efficient (i.e. attains the optimal asymptotic variance). In the second case, we prove that the quadratic risk of any estimator does not converge at parametric rate. In the second part of the dissertation, we focus on the estimation of the nonparametric unknown component f in the mixture, relying on a preliminary estimator of p. We propose and study the asymptotic properties of two different estimators for this unknown component. The first estimator is a randomly weighted kernel estimator. We establish an upper bound for its pointwise quadratic risk, exhibiting the classical nonparametric rate of convergence over a class of Holder densities. The second estimator is a maximum smoothed likelihood estimator. It is computed through an iterative algorithm, for which we establish a descent property. In addition, these estimators are used in a multiple testing procedure in order to estimate the local false discovery rate.

BATISTA, Leidiane Priscilla de Paiva. Saberes Etnoictiológicos dos Pescadores Artesanais nos Açudes do Alto Rio Acaraú, Ceará, Brasil. 2012. 102 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências e Tecnologia, Programa de Pós-Graduação em Desenvolvimento e Meio Ambiente-PRODEMA, Fortaleza-CE, 2012. / Submitted by guaracy araujo (guaraa3355@gmail.com) on 2016-05-03T16:43:04Z No. of bitstreams: 1 2012_dis_ lppbatista.pdf: 14346238 bytes, checksum: cd0e7a424d9c932b857183e761c3733b (MD5) / Approved for entry into archive by guaracy araujo (guaraa3355@gmail.com) on 2016-05-03T16:46:23Z (GMT) No. of bitstreams: 1 2012_dis_ lppbatista.pdf: 14346238 bytes, checksum: cd0e7a424d9c932b857183e761c3733b (MD5) / Made available in DSpace on 2016-05-03T16:46:23Z (GMT). No. of bitstreams: 1 2012_dis_ lppbatista.pdf: 14346238 bytes, checksum: cd0e7a424d9c932b857183e761c3733b (MD5) Previous issue date: 2012 / The ethnoictiology to describe and use the knowledge of fishermen, by studies that show that they are carriers of bio-ecological knowledge about fish they catch. Thus, the objective was to compare the knowledge of fishermen of public dams Araras and Edson Queiroz (Middle Acaraú River Basin, Ceará) with the scientific literature. With this end, we selected a representative population for each of these reservoirs. Therefore, there is the Ilha de Esaú, for the dam Araras, and Vila São Cosme, to Edson Queiroz. Were performed participant observation, semi-structured interviews, visual stimulus, and guided fishing tours of these populations. Twenty fishermen were interviewed in Vila Sao Cosme and twenty-four on the Ihla de Esaú The interviews aspects ethnoecological of the main fish species caught by fishermen. Were cited twenty ethnospecies fish and shrimp as captured in the reservoirs. Among these, the most important, economically, are cará-tilapia [Oreochromis niloticus (Linnaeus, 1758) and Tilapia rendalli (Boulenger, 1897)], curimatã [(Prochilodus brevis (Steindachner, 1874)], pescada [Plagiossion squamossimus (Heckel, 1840)], piau (Leporinus sp.),traíra (Hoplias brasiliensis e H. malabaricus) and tucunaré [Cichla cf. ocellaris (Bloch; Schneider, 1801)]. In the classification of fishes, fishemen used morphological and ethological aspects, presenting several ethnospecies with generic names and few with binomial names. In your diet, these populations consume fish as the main source of animal protein, with social and cultural restrictions. As for ethnoictiology, it is concluded that the fishermen have consistent knowledge about the general ecology, trophic and reproductive of fishes captured. Therefore, the consistency of the knowledge of fishermen on the Ilha de Esaú and Vila São Cosme, this knowledge can contribute to future scientific studies and be incorporated in the preparation of management plans and sustainable management of water resources and fisheries in the middle region Acaraú. / A etnoictiologia busca descrever e valorizar os conhecimentos dos pescadores artesanais, através de estudos que evidenciam que estes são portadores de conhecimentos bioecológicos acerca dos peixes que capturam. Desta forma, objetivou-se comparar os conhecimentos etnoictiológicos dos pescadores artesanais dos açudes públicos Araras e Edson Queiroz (bacia do médio rio Acaraú-CE) com a literatura científica. Com este fim, selecionou-se uma população representativa para cada um destes açudes. Assim, tem-se a Ilha de Esaú, para o açude Araras, e Vila São Cosme, para o Edson Queiroz. Foram realizadas observação participante, entrevistas semiestruturadas, estímulo visual e turnês-guiadas com pescadores destas populações. Foram entrevistados vinte pescadores na Vila São Cosme e vinte e quatro na Ilha de Esaú. As entrevistas abordaram aspectos etnoecológicos das principais espécies de peixes capturadas pelos pescadores. Foram citadas vinte etnoespécies de peixes e uma de camarão como sendo capturadas nos açudes. Dentre estas, as mais importantes, economicamente, foram: cará-tilápia (Oreochromis niloticus Linnaeus, 1758 e Tilapia rendalli Boulenger, 1897), curimatã (Prochilodus brevis Steindachner, 1874), pescada, (Plagiossion squamossimus Heckel, 1840), piau (Leporinus sp.), traíra (Hoplias brasiliensis e H. malabaricus Bloch, 1794) e tucunaré (Cichla cf. ocellaris Bloch; Schneider, 1801). Na classificação da ictiofauna, os pescadores utilizam aspectos morfológicos e etológicos, apresentando várias etnoespécies com nomes genéricos e poucas com nomes binomiais. Em sua dieta, estas populações consomem peixes, como principal fonte de proteína animal, havendo restrições por caráter social e cultural. Quanto à etnoictiologia, conclui-se que os pescadores possuem conhecimentos consistentes sobre a ecologia geral, trófica e reprodutiva da ictiofauna capturada, vivenciando empiricamente muitas das informações presentes na literatura acadêmica. Logo, pela consistência dos saberes dos pescadores da Ilha de Esaú e da Vila São Cosme, estes conhecimentos podem contribuir para futuros estudos científicos e ser incorporados na elaboração de planos de gestão e manejo sustentável dos recursos hídricos e pesqueiros da região média do Acaraú.

Made available in DSpace on 2015-05-15T11:46:09Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 652579 bytes, checksum: a75e379418567b71eed4fc021cfeeae6 (MD5) Previous issue date: 2011-08-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / We start studing semi-stable solutions for the equation u = f(u) in a smooth and bounded domain of Rn, 2 n 4. The presented result is a L1 boundedness, which holds for all semi-stable positive solution and all non-linearity f. We also show a approach about the case u = f(u) in the unitary ball of Rn. The results obtained are Lq and Wk;q estimates for semi-stable radial solutions u 2 H1 0 , the proof of a boundedness if n 9 and, in case that g is increasing and convex, u 2 W3;2 in all dimension n. / Começamos estudamos soluções semi-estáveis para a equação u = f(u) em um domínio suave limitado do Rn, 2 n 4. O resultado apresentado é uma limitação L1 a qual vale para toda solução positiva semi-estável e toda nãolinearidade f. Mostramos também uma abordagem sobre o caso u = f(u) na bola unitária do Rn. Os resultados obtidos são estimativas em Lq e Wk;q para soluções semi-estáveis radiais u 2 H1 0 , a prova de uma limitação se n 9 e, no caso em que g é crescente e convexa, u 2 W3;2 em toda dimensão n.

Made available in DSpace on 2015-04-11T14:03:04Z (GMT). No. of bitstreams: 1 Daniel Pereira de Oliveira.pdf: 1962605 bytes, checksum: 022c425ec0a87d2146c7cae3f274903b (MD5) Previous issue date: 2006-03-03 / In the current days, the Internet has become the largest information repository available. However, this huge variety of information is mostly represented in textual format and it necessarily requires human intervention to be effectively used. On the other hand, there exists a large set of Web pages that are in fact composed of collections of implicit data objects. For instance, on-line catalogs, digital libraries and e-commerce Web sites in general. Extracting the contents of these pages and identifying the structure of the data objects available allow for more sophisticated forms of processing besides hyperlink browsing and keyword-based searching. The task of extracting data from Web pages is usually executed by specialized programs called wrappers. In the present work we propose and evaluate a new approach to the wrapper development problem. In this approach, the user is only responsible for providing examples for the atomic items that constitute the objects of interest. Based on these examples, our method automatically generates expressions for extracting other atomics items similar to those presented as example and infers a plausible and meaningful structure to organize them. Our method for generating extraction expression uses techniques inherited from solutions for the multiple string alignment problem. The method is able to produce good extraction expressions that can be easily encoded as regular expressions. Inferring a meaningful structure for the objects whose atomic values were extracted is the task of the HotCycles algorithm, that were previously proposed and which we have revised and extended in this work. The algorithm assembles an adjacency graph for these atomic values, and executes a structural analysis over this graph, looking for patterns that resemble structural constructs such as tuples and lists. From such constructs, a complex object type can be assigned to the extracted data. The experiments carried out using 21 collections of real Web pages have demonstrated the feasibility of our extraction method, reaching 94% of effectiveness using no more than 10 examples for each attribute. The HotCycles algorithm was able to infer a meaningful structure for the objects present in all used collections. Its effectiveness, combined with our atom extraction method, reached 97% of structures correctly inferred, also using no more than 10 examples per attribute. The association of these two methods has demonstrated to be extremely feasible. The high number of correctly inferred structures together with the high precision and recall values of the extraction process demonstrates that this new approach is indeed a promising one. / Hoje em dia a Web se apresenta como o maior repositório de informações da humanidade. Contudo, essa imensa gama de informação é formada principalmente por conteúdo textual e necessariamente requer interpretação humana para se tornar útil. Por outro lado, existe uma grande quantidade de páginas na Web que são, na verdade, formadas por um conjunto implícito de objetos. Isso ocorre, por exemplo, em páginas oriundas de sites de catálogos on-line, bibliotecas digitais e comércio eletrônico em geral. A extração desse conteúdo e a identificação da estrutura dos objetos disponíveis permite uma forma mais sofisticada de processamento além da tradicional navegação por hiperlinks e consultas por palavras-chave. A tarefa de extrair dados de páginas Web é executada por progamas chamados extratores ou wrappers. Neste trabalho propomos uma nova abordagem para o desenvolvimento de extratores. Nessa abordagem o usuário se restringe a fornecer exemplos de treinamento para os atributos que constituem os objetos de interesse. Baseado nesses exemplos, são gerados automaticamente padrões para extrair dados inseridos em contextos similares áqueles fornecidos como exemplos. Em seguida, esses dados são automaticamente organizados segundo uma estrutura plausível. Nosso método de geração de padrões de extração utiliza técnicas herdadas de soluções para o problema do alinhamento múltiplo de seqüências. O método é capaz de produzir padrões de extração que podem ser facilmente transformados em expressões regulares. A tarefa de inferir uma estrutura plausível para os objetos extraídos é realizada pelo algoritmo HotCycles, que foi previamente proposto e que foi revisto e ampliado neste trabalho. O algoritmo constrói um grafo de adjacências para esses dados, e realiza nele, uma análise estrutural em busca de padrões que indiquem construtores estruturais como tuplas e listas. A partir de tais construtores, é associado um tipo aninhado aos dados que foram extraídos da página. Experimentos realizados em 21 coleções de páginas reais da Web demonstram a viabilidade do método de extração de valores atômicos, obtendo um desempenho superior a 94% e utilizando no máximo 10 exemplos de treinamento por atributo. O algoritmo HotCycles foi capaz de inferir uma estrutura plausível para os objetos em todas as coleções utilizadas. Seu desempenho combinado com o método de extração de valores atômicos chegou a 97% de estruturas corretamente inferidas com a utilização também até 10 exemplos por atributo. A combinação desses dois métodos demonstrou-se extremamente viável. Os altos índices de estruturas corretamente inferidas juntamente com os elevados índices de precisão e revocação do processo de extração demonstram que esta é sem dúvida uma abordagem promissora.