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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.
31

Seismic stratigraphy and fluid flow in the Taranaki and Great South Basins, offshore New Zealand

Chenrai, Piyaphong January 2016 (has links)
This study utilises seismic data to improve understanding of the subsurface fluid flow behaviour in the Taranaki and Great South Basins offshore New Zealand. The aim of this study is to characterise fluid flow features and to investigate their genesis, fluid origins and implications for subsurface fluid plumbing system by integrating seismic interpretation and 3D petroleum systems modelling techniques. After an early phase studying Pliocene pockmarks in the Taranaki Basin, this study has been focused on the subsurface fluid plumbing system and on the fluid expulsion history in the Great South Basin. The Taranaki Basin lies on the west coast and offshore of the North Island, New Zealand. The seismic interpretation revealed that paleo-pockmark formation in the study area relates to fluid escape due to a rapid sediment loading environment in a distal fan setting. Seismic analysis rules out any links between the paleo-pockmarks and faulting. The relationship between paleo-pockmark occurrence and fan depositional thickness variations suggests that pore-water expulsion during overburden progradation is the most likely cause of the paleo-pockmarks. The rapid sediment loading generated overpressure which was greatest on the proximal fan due to a lateral gradient in overburden pressure. Fluids were consequently forced towards the fan distal parts where, eventually, the pore pressure exceeded the fracture gradient of the seal. The Great South Basin lies off the southern coast of the South Island of New Zealand and is located beneath the modern shelf area. Evidence for past and present subsurface fluid flow in this basin is manifested by the presence of numerous paleo-pockmarks, seabed pockmarks, polygonal fault systems, bright spots and bottom simulating reflections (BSR), all of which help constrain aspects of the overburden plumbing system and may provide clues to deeper hydrocarbon prospectivity in this frontier region. The various types of fluid flow features observed in this study are interpreted to be caused by different fluid origins and mechanisms based on evidences from seismic interpretation in the study area. The possible fluid origins which contribute to fluid flow features in the Great South Basin are compactional pore water as well as biogenic and thermogenic hydrocarbons. Using 3D seismic attribute analysis it was possible to highlight the occurrence of these features, particularly polygonal faults and pockmarks, which tend to be hosted within fine-grained sequences. Paleo- and present-day fluid flow features were investigated using 3D basin and petroleum systems modelling with varying heat flow scenarios. The models predict that thermogenic gas is currently being generated in mid-Cretaceous sedimentary sequences and possibly migrates along tectonic faults and polygonal faults feeding present-day pockmarks at the seabed. The models suggest that biogenic gas was the main fluid source for the Middle Eocene paleo-pockmarks and compactional pore fluid may be the main fluid contributor to the Late Eocene paleo-pockmarks. Different heat flow scenarios show that only mid-Cretaceous source rocks have reached thermal maturity in the basin, whilst Late Cretaceous and Paleocene source rocks would be largely immature. The observations and interpretations provided here contribute to the ongoing discussion on basin de-watering and de-gassing and the fluid contributors involved in pockmark formation and the use of pockmarks as a potential indicator of hydrocarbon expulsion. It is clear from this study that seismically-defined fluid flow features should be integrated into petroleum systems modelling of frontier and mature exploration areas in order to improve our understanding on fluid phases, their migration routes, timings and eventual expulsion history.
32

Desenvolvimento de projeto gráfico para interface de usuário de software de modelagem tridimensional : uma abordagem ergonômica

Ballarini, Dorothy Silveira January 2009 (has links)
Esta dissertação apresenta um framework de desenvolvimento de uma interface gráfica de usuário para um sistema de modelagem poligonal tridimensional, a partir de critérios ergonômicos que atendam os requisitos fundamentais de usabilidade. A pesquisa foi especialmente orientada a satisfazer principalmente as necessidades individuais dos diferentes perfis de usuários que fazem uso de aplicações similares. Para isto, foram estudados conceitos pertinentes às áreas de Ergonomia, Usabilidade e Interação Humano-Computador. Isto permitiu obter estratégias que podem ser utilizadas durante o estágio de concepção de uma interface de usuário, a fim de promover e garantir a ergonomia de um sistema em estágios anteriores à sua implementação, economizando recursos e prevenindo possíveis problemas de usabilidade. Um dos aspectos fundamentais do protótipo proposto nesta dissertação é a sua adaptabilidade, onde um dos benefícios da utilização deste tipo de recurso é a capacidade de reduzir a complexidade durante o aprendizado de um sistema por usuários novatos, selecionando informações essenciais e indicando as próximas ações possíveis, já que o sistema proposto baseia-se nos resultados de passos anteriores. A técnica de avaliação desta interface gráfica utiliza uma lista de verificação (checklist) ergonômica, que é escolhida por suas características adequadas às delimitações do projeto de pesquisa. / This dissertation aims the development of a non-functional prototype for a graphical user interface of a 3D polygonal modeling system based on ergonomic criteria that meet the basic requirements of usability. The research was specifically targeted to meet the individual needs of customers who make use of similar applications. For this purpose, relevant concepts of Ergonomics, Usability and Human-Computer Interaction were studied. It allowed this research to obtain strategies that can be used during the design stage of a user interface in order to promote and ensure the software ergonomics at stages prior to implementation, saving resources, preventing possible usability problems. One of the key aspects of the proposed prototype is its adaptability, and one of its benefits of this feature is the ability to reduce the learning complexity of the system for novice users, by selecting key information and indicating the next possible actions, since the proposed system is based on results of previous steps. The ergonomics evaluation of this graphical interface was made using a checklist, which was chosen for being appropriate to this research. The results confirm the usability of the User Interface, thus validating the use of this proposal as a development framework.
33

Desenvolvimento de projeto gráfico para interface de usuário de software de modelagem tridimensional : uma abordagem ergonômica

Ballarini, Dorothy Silveira January 2009 (has links)
Esta dissertação apresenta um framework de desenvolvimento de uma interface gráfica de usuário para um sistema de modelagem poligonal tridimensional, a partir de critérios ergonômicos que atendam os requisitos fundamentais de usabilidade. A pesquisa foi especialmente orientada a satisfazer principalmente as necessidades individuais dos diferentes perfis de usuários que fazem uso de aplicações similares. Para isto, foram estudados conceitos pertinentes às áreas de Ergonomia, Usabilidade e Interação Humano-Computador. Isto permitiu obter estratégias que podem ser utilizadas durante o estágio de concepção de uma interface de usuário, a fim de promover e garantir a ergonomia de um sistema em estágios anteriores à sua implementação, economizando recursos e prevenindo possíveis problemas de usabilidade. Um dos aspectos fundamentais do protótipo proposto nesta dissertação é a sua adaptabilidade, onde um dos benefícios da utilização deste tipo de recurso é a capacidade de reduzir a complexidade durante o aprendizado de um sistema por usuários novatos, selecionando informações essenciais e indicando as próximas ações possíveis, já que o sistema proposto baseia-se nos resultados de passos anteriores. A técnica de avaliação desta interface gráfica utiliza uma lista de verificação (checklist) ergonômica, que é escolhida por suas características adequadas às delimitações do projeto de pesquisa. / This dissertation aims the development of a non-functional prototype for a graphical user interface of a 3D polygonal modeling system based on ergonomic criteria that meet the basic requirements of usability. The research was specifically targeted to meet the individual needs of customers who make use of similar applications. For this purpose, relevant concepts of Ergonomics, Usability and Human-Computer Interaction were studied. It allowed this research to obtain strategies that can be used during the design stage of a user interface in order to promote and ensure the software ergonomics at stages prior to implementation, saving resources, preventing possible usability problems. One of the key aspects of the proposed prototype is its adaptability, and one of its benefits of this feature is the ability to reduce the learning complexity of the system for novice users, by selecting key information and indicating the next possible actions, since the proposed system is based on results of previous steps. The ergonomics evaluation of this graphical interface was made using a checklist, which was chosen for being appropriate to this research. The results confirm the usability of the User Interface, thus validating the use of this proposal as a development framework.
34

Polohová a výšková detekce části vodního toku Ostřice v k.ú. Horní Planá. / Planimetry and altitude detection in the part of the stream Ostřice in the cadastral region Horní Planá.

KOHOUT, Jaromír January 2009 (has links)
This thesis is focused on using selected geodetic methods for tracing a part of the river Ostřice, located in cadastral area of Horní Planá, district Český Krumlov. The objective of this work is to identify, demarcate and trace a file of fixed points setting river polygonal traverse and their further usage as a base for determining the stream longitudinal section. The theoretical part contains information about the minor control and geodetic activities done within it and related to this thesis. The practical part consists of service area{\crq}s characteristic, procedures description and elaboration of results including their graphic exemplification.
35

Desenvolvimento de projeto gráfico para interface de usuário de software de modelagem tridimensional : uma abordagem ergonômica

Ballarini, Dorothy Silveira January 2009 (has links)
Esta dissertação apresenta um framework de desenvolvimento de uma interface gráfica de usuário para um sistema de modelagem poligonal tridimensional, a partir de critérios ergonômicos que atendam os requisitos fundamentais de usabilidade. A pesquisa foi especialmente orientada a satisfazer principalmente as necessidades individuais dos diferentes perfis de usuários que fazem uso de aplicações similares. Para isto, foram estudados conceitos pertinentes às áreas de Ergonomia, Usabilidade e Interação Humano-Computador. Isto permitiu obter estratégias que podem ser utilizadas durante o estágio de concepção de uma interface de usuário, a fim de promover e garantir a ergonomia de um sistema em estágios anteriores à sua implementação, economizando recursos e prevenindo possíveis problemas de usabilidade. Um dos aspectos fundamentais do protótipo proposto nesta dissertação é a sua adaptabilidade, onde um dos benefícios da utilização deste tipo de recurso é a capacidade de reduzir a complexidade durante o aprendizado de um sistema por usuários novatos, selecionando informações essenciais e indicando as próximas ações possíveis, já que o sistema proposto baseia-se nos resultados de passos anteriores. A técnica de avaliação desta interface gráfica utiliza uma lista de verificação (checklist) ergonômica, que é escolhida por suas características adequadas às delimitações do projeto de pesquisa. / This dissertation aims the development of a non-functional prototype for a graphical user interface of a 3D polygonal modeling system based on ergonomic criteria that meet the basic requirements of usability. The research was specifically targeted to meet the individual needs of customers who make use of similar applications. For this purpose, relevant concepts of Ergonomics, Usability and Human-Computer Interaction were studied. It allowed this research to obtain strategies that can be used during the design stage of a user interface in order to promote and ensure the software ergonomics at stages prior to implementation, saving resources, preventing possible usability problems. One of the key aspects of the proposed prototype is its adaptability, and one of its benefits of this feature is the ability to reduce the learning complexity of the system for novice users, by selecting key information and indicating the next possible actions, since the proposed system is based on results of previous steps. The ergonomics evaluation of this graphical interface was made using a checklist, which was chosen for being appropriate to this research. The results confirm the usability of the User Interface, thus validating the use of this proposal as a development framework.
36

Ray Tracing Non-Polygonal Objects: Implementation and Performance Analysis using Embree

Carlie, Michael January 2016 (has links)
Free-form surfaces and implicit surfaces must be tessellated before being rendered with rasterization techniques. However ray tracing provides the means to directly render such objects without the need to first convert into polygonal meshes. Since ray tracing can handle triangle meshes as well, the question of which method is most suitable in terms of performance, quality and memory usage is addressed in this thesis. Bézier surfaces and NURBS surfaces along with basic algebraic implicit surfaces are implemented in order to test the performance relative to polygonal meshes approximating the same objects. The parametric surfaces are implemented using an iterative Newtonian method that converges on the point of intersection using a bounding volume hierarchy that stores the initial guesses. Research into intersecting rays with parametric surfaces is surveyed in order to find additional methods that speed up the computation. The implicit surfaces are implemented using common direct algebraic methods. All of the intersection tests are implemented using the Embree ray tracing API as well as a SIMD library in order to achieve interactive framerates on a CPU. The results show that both Bézier surfaces and NURBS surfaces can achieve interactive framerates on a CPU using SIMD computation, with Bézier surfaces coming close to the performance of polygonal counterparts. The implicit surfaces implemented outperform even the simplest polygonal approximations.
37

Polygonal models from range scanned trees

Qiu, Li January 2009 (has links)
3D Models of botanical trees are very important in video games, simulation, virtual reality, digital city modeling and other fields of computer graphics. However, since the early days of computer graphics, the modeling of trees has been challenging, because of the huge dynamical range between its smallest and largest structures and their geometrical complexity. Trees are also ubiquitous which makes it even hard to model them in a realistic way, Current techniques are limited in that they model a tree either in a rule-based way or in an approximated way. These methods emphasize appearance while sacrificing its real structure. Recent development in range scanners are making 3D aquisition feasible for large and complex objects. This report presents the semi-automatic technique developed for modeling laser-scanned trees. First, the user draws a few strokes on the depth image plane generated from the dataset. Branches are then extracted through the 2D Curve detection algorithm originally developed. Afterwards, those short branches are connected together to generate the skeleton of the tree by forming a Minimum Spanning Tree (MST). Finally, the geometry of the tree skeleton is produced using allometric rules for branch thickness and branching angles.
38

Vers un efficace détecteur de trait : Les coins de contour et ses applications / Toward an efficient feature detector : Edge corners and its applications

Al Nachar, Rabih 06 November 2014 (has links)
Nous proposons dans cette thèse un nouveau détecteur de « Coins » de contour dans une image. Ces coins sont les sommets de la ligne polygonale approximant le contour. Ils peuvent appartenir ou non au contour. Ils correspondent à une déviation importante de la direction de ce contour. Aussi, ils sont répétables en présence de transformations affines ou similitudes et sont robustes au bruit présent aux frontières d'une image. Grâce à cette répétabilité, les coins sont utilisés dans une application de reconnaissance de la forme.Les coins peuvent être classés selon leur force. Ainsi sous ensemble de ces coins,appelé "Coins Dominants", peuvent être extraits formant les sommets du polygone« minimal » qui représente le contour, pour un nombre de segments donné. Deux applications, basées sur les Coins/Coins Dominants du contour ont été réalisées : La première est une application de recalage d’images où de nouvelles primitives invariantes constituées de quatre "Coins Dominants" du contour ont été proposées. La seconde application est la reconnaissance des caractères dans une image déformée où les coins du contour des caractères ont été utilisés dans un processus de segmentation / reconnaissance simultané. / In this thesis, a new feature detector is proposed. The new features are edgecorners located on the contours of a studied image. These points are edge pointswhere a deviation in the edge direction occurs. In addition, they are repeatable versussimilarity, affine transformations and also robust to noise at the boundaries of theobject's image. Due to their repeatability, these corners are used in a shape recognitionapplication. Also, a smaller set of corners called "Dominant Corners" or "DCs" isextracted form the original set of corners using a new proposed polygonalapproximation algorithm. These DCs form the vertices of a polygon that bestapproximate their contour. Two applications using the edge corners are alsodeveloped. The first one is an image registration application that forms invariantprimitives using the DCs. The second application is a word recognition applicationwhere the edge corners located on the characters contours are used in a simultaneoussegmentation/recognition process to recognize the characters in a deformed wordimage.
39

Analýza polygonálních modelů pomocí neuronových sítí / Analysis of Polygonal Models Using Neural Networks

Dronzeková, Michaela January 2020 (has links)
This thesis deals with rotation estimation of 3D model of human jaw. It describes and compares methods for direct analysis od 3D models as well as method to analyze model using rasterization. To evaluate perfomance of proposed method, a metric that computes number of cases when prediction was less than 30° from ground truth is used. Proposed method that uses rasterization, takes  three x-ray views of model as an input and processes it with convolutional network. It achieves best preformance, 99% with described metric. Method to directly analyze polygonal model as a sequence uses attention mechanism to do so and was inspired by transformer architecture. A special pooling function was proposed for this network that decreases memory requirements of the network. This method achieves 88%, but does not use rasterization and can process polygonal model directly. It is not as good as rasterization method with x-ray display, byt it is better than rasterization method with model not rendered as x-ray.  The last method uses graph representation of mesh. Graph network had problems with overfitting, that is why it did not get good results and I think this method is not very suitable for analyzing plygonal model.
40

Combinatorial Models for DNA Rearrangements in Ciliates

Angeleska, Angela 20 May 2009 (has links)
Motivated by genome rearrangements that take place in some species of ciliates we introduce a combinatorial model for these processes based on spatial graphs. This model builds up on two earlier models for pointer-guided DNA recombination (intramolecular model introduced in [22, 23] and intermolecular model introduced in [35, 36]) and is influenced by a molecular model for RNA guided DNA recombination (introduced in [2]). Despite their differences, the intermolecular and intramolecular model formalize the recombination events through rewriting operations applied on formal words. Both models predict the same set of molecules as a result of correct rearrangement. Here, we give an algorithm that for an input of scrambled gene structure outputs a set of strings which represents the expected set of molecules after complete assembly. Moreover, we prove that both the set of all realistic words (words that model a possible gene structure) and the set of all nonrealistic words are closed under the rewriting operations in the intramolecular model. We investigate spatial graphs that consist of 4-valent rigid vertices, called assembly graphs. An assembly graph can be seen as a representation of DNA molecule during certain recombination processes, in which 4-valent vertices represent molecular alignment of the recombination sites. We introduce a notion of polygonal path in assembly graph as a model for a single gene. Polygonal paths are defined as paths that make “90◦ -turn” at each vertex of the assembly graph and define smoothing of the vertices visited by the paths. Such vertex smoothing models a homologous DNA recombination. We investigate the minimal number of polygonal paths that visit all vertices of a given graph exactly once, called assembly number. We prove that for every positive integer n there is assembly graph with assembly number n. We also study the relationship between the number of vertices in assembly graph and its assembly number. One of the results is that every assembly graph with assembly number n has at least 3n − 2 vertices. In addition, we show that there is an embedding in three dimensional space of each assembly graph with a given set of polygonal paths, such that smoothing of vertices with respect to the polygonal paths results in unlinked circles. We study the recombination strategies by subsets of vertices. Such a subset is called a successful set if smoothing of all vertices from the set with respect to a polygonal path results in a graph that contains the polygonal path in a single component. We characterize the successful sets in a given assembly graph by a notion of complementary polygonal path. Furthermore, we define a smoothing strategy in assembly graph relative to a polygonal path as a sequence of successful sets which model a successive DNA recombinations for correct gene assembly. Recent experimental results suggest that there might be different pathways for unscrambling a gene. These results lead to a mathematical model for gene recombination that builds upon the intermolecular model. We introduce assembly words as a formalization of a set of linear and circular DNA molecules. Assembly words are partially ordered, so that any linearly ordered subset models a pathway for gene rearrangement. We suggest two different pathways for unscrambling of the actin I gene in O.Trifallax and we prove that they are the only theoretically possible pathways.

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