Dissertations / Theses on the topic 'Geometry fusion'
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Builth-Williams, Joseph Douglas. "Geometrically and Reflectively Enhanced Embedded Fusion." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/23256.
JUNIOR, ANTONIO CESAR PINHO BRASIL. "HEAT TRANSFER DURING THE FUSION IN A VERTICAL CYLINDRICAL GEOMETRY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1985. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33303@1.
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Uma análise experimental é desenvolvida para avaliação da transferência de calor durante a fusão ao redor de um cilindro isotérmico vertical imerso em um meio de mudança de fase. A posição e forma da interface sólido-líquido é determinada como função do tempo, para diferentes temperaturas do cilindro. A relação altura/diâmetro é de cinco, para comparação com resultados já existentes. A faixa de Número de Stefan investigado foi de 0,017 a 0,33 o que equivale a uma faixa de Número Rayleigh de 7x10 elevado a quarta potência a 2x10 elevado a sexta potência. Os dados obtidos foram utilizados para a determinação dos números de Nusselt locais na interface e médios para a superfície do cilindro. A dependência da massa fundida com o tempo foi também determinada, parametrizada por Rayleigh. Soluções do problema de fusão sem os efeitos de convecção natural (Problema tipo STEFAN) foram obtidos via método de elementos finitos e estes resultados foram comparados com os dados experimentais obtidos. Isto permitiu a determinação do tempo quando os efeitos de convecção natural tornam-se importantes. Comparações com resultados numéricos publicados, para a mesma condição física, foram desenvolvidas obtendo excelentes concordâncias.
An experimental investigation was performed to determine heat transfer coefficients during the outward melting of a phase-change material (PCM),maintained at its fusion temperature, around an isothermal cylinder positioned vertically. The position and shape of the Solid-liquid interface were determined as a function of time, for diferent temperatures of the cylinder. The ratio height-to-diameter of the cylinder was chosen to be five, in order to allow comparisons with available results. The Stefan number range investigated was 0,017 - 0,33 corresponding to a Rayleigh number variation from 7x10 to the fourth power to 2x10 to the sixth power. The data obtained was used in the determination of local Nusselt numbers for the interface and average Nusselt numbers for cylinder surface. The dependence of the molten mass on time was also determined, for several combinations of the relevant parameters. Solutions of the axisymmetric melting problem without natural convection effects (Stefan-like problem) were obtained via finite-element analysis. These numerical results were compared with the experimental data, which permitted the determination of times when the natural convection effects in the liquid region become of importance. The experimental data were compared with the results of an available numerical analysis of the same physical situation, and excellent agreement was obtained.
Durbin, Samuel Glen. "Dynamics and free-surface geometry of turbulent liquid sheets." Available online, Georgia Institute of Technology, 2005:, 2005. http://etd.gatech.edu/theses/available/etd-03032005-095517/unrestricted/Durbin%5FSamuel%5FG%5F200505%5Fphd.pdf.
Minami Yoda, Committee Co-Chair ; Said I. Abdel-Khalik, Committee Co-Chair ; S. Mostafa Ghiaasiaan, Committee Member ; Cyrus K. Aidun, Committee Member ; Donald R. Webster, Committee Member ; Ralph W. Moir, Committee Member. Includes bibliographical references.
Abdullah, Ramli Bin. "Bond behaviour of fusion bonded epoxy coated reinforcement : influence of bar rib geometry." Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/805.
Aguilar, Quiñones Valeria. "Impact of Viral Geometry and Cellular Lipid Environment on Virus-Endosome Fusion Kinetics." Thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-446545.
Wang, Chao. "Point clouds and thermal data fusion for automated gbXML-based building geometry model generation." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54008.
Gallo, Alberto. "Impact of the plasma geometry on the divertor power exhaust in a magnetic fusion reactor." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0001/document.
A deep understanding of plasma transport at the edge of a magnetically confined fusion device is mandatory for a sustainable and controlled handling of the power exhaust. In the next-generation fusion device ITER, technological limits constrain the peak heat flux on the divertor. For a given exhaust power the peak heat flux is determined by the extent of the plasma footprint on the wall. Heat flux profiles at the divertor targets of X-point configurations can be parametrized by using two length scales for the transport of heat in SOL. In this work, we challenge the current interpretation of these two length scales by studying the impact of divertor geometry modifications on the heat exhaust. In particular, a significant broadening of the heat flux profiles at the outer divertor target is diagnosed while increasing the length of the outer divertor leg. Modelling efforts showed that diffusive simulations well reproduce the experimental heat flux profiles for short-legged plasmas. Conversely, the broadening of the heat flux for a long divertor leg is reproduced by a turbulent model, highlighting the importance of turbulent transport not only in the main SOL but also in the divertor. These results question the current interpretation of the heat flux width as a purely main SOL transport length scale. In fact, long divertor leg magnetic configurations highlighted the importance of asymmetric divertor transport. We therefore conclude that main SOL and divertor SOL transport cannot be arbitrarily disentangled and we underline the importance of the divertor magnetic geometry in enhancing asymmetric turbulent transport with the potential benefit of an unexpected power spreading
Gallo, Alberto. "Impact of the plasma geometry on the divertor power exhaust in a magnetic fusion reactor." Electronic Thesis or Diss., Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0001.
A deep understanding of plasma transport at the edge of a magnetically confined fusion device is mandatory for a sustainable and controlled handling of the power exhaust. In the next-generation fusion device ITER, technological limits constrain the peak heat flux on the divertor. For a given exhaust power the peak heat flux is determined by the extent of the plasma footprint on the wall. Heat flux profiles at the divertor targets of X-point configurations can be parametrized by using two length scales for the transport of heat in SOL. In this work, we challenge the current interpretation of these two length scales by studying the impact of divertor geometry modifications on the heat exhaust. In particular, a significant broadening of the heat flux profiles at the outer divertor target is diagnosed while increasing the length of the outer divertor leg. Modelling efforts showed that diffusive simulations well reproduce the experimental heat flux profiles for short-legged plasmas. Conversely, the broadening of the heat flux for a long divertor leg is reproduced by a turbulent model, highlighting the importance of turbulent transport not only in the main SOL but also in the divertor. These results question the current interpretation of the heat flux width as a purely main SOL transport length scale. In fact, long divertor leg magnetic configurations highlighted the importance of asymmetric divertor transport. We therefore conclude that main SOL and divertor SOL transport cannot be arbitrarily disentangled and we underline the importance of the divertor magnetic geometry in enhancing asymmetric turbulent transport with the potential benefit of an unexpected power spreading
Fay, Robert H. "Application of the Fusion Model for Cognitive Diagnostic Assessment with Non-diagnostic Algebra-Geometry Readiness Test Data." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7285.
Walker, Joseph R. "Multi-Sensor Approach to Determine the Effect of Geometry on Microstructure in Additive Manufacturing." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1558900598369986.
Cherif, Mohamed Abderrazak. "Alignement et fusion de cartes géospatiales multimodales hétérogènes." Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ5002.
The surge in data across diverse fields presents an essential need for advanced techniques to merge and interpret this information. With a special emphasis on compiling geospatial data, this integration is crucial for unlocking new insights from geographic data, enhancing our ability to map and analyze trends that span across different locations and environments with more authenticity and reliability. Existing techniques have made progress in addressing data fusion; however, challenges persist in fusing and harmonizing data from different sources, scales, and modalities.This research presents a comprehensive investigation into the challenges and solutions in vector map alignment and fusion, focusing on developing methods that enhance the precision and usability of geospatial data. We explored and developed three distinct methodologies for polygonal vector map alignment: ProximityAlign, which excels in precision within urban layouts but faces computational challenges; the Optical Flow Deep Learning-Based Alignment, noted for its efficiency and adaptability; and the Epipolar Geometry-Based Alignment, effective in data-rich contexts but sensitive to data quality. Additionally, our study delved into linear feature map alignment, emphasizing the importance of precise alignment and feature attribute transfer, pointing towards the development of richer, more informative geospatial databases by adapting the ProximityAlign approach for linear features like fault traces and road networks. The fusion aspect of our research introduced a sophisticated pipeline to merge polygonal geometries relying on space partitioning, non-convex optimization of graph data structure, and geometrical operations to produce a reliable fused map that harmonizes input vector maps, maintaining their geometric and topological integrity.In practice, the developed framework has the potential to improve the quality and usability of integrated geospatial data, benefiting various applications such as urban planning, environmental monitoring, and disaster management. This study not only advances theoretical understanding in the field but also provides a solid foundation for practical applications in managing and interpreting large-scale geospatial datasets
Narra, Sneha Prabha. "Melt Pool Geometry and Microstructure Control Across Alloys in Metal Based Additive Manufacturing Processes." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/914.
Grosjean, Alex. "Impact of geometry and shaping of the plasma facing components on hot spot generation in tokamak devices." Electronic Thesis or Diss., Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0556.
This PhD falls within ITER project support, aiming to study the thermal behavior of ITER-like PFC prototypes in two superconducting tokamaks: EAST (Hefei) and WEST (Cadarache). These prototypes correspond to castellated tungsten monoblocks placed along a cooling tube with small gaps (0.5 mm) between them, called plasma-facing units, to extract the heat from the components. The introduction of gaps between monoblocks (toroidal) and plasma-facing units (poloidal), to relieve the thermomechanical stresses in the divertor, implies that poloidal leading edges may be exposed to near-normal incidence angle. A local overheating is expected in a thin lateral band at the top of each monoblocks, which can be enhanced when the neighboring components are misaligned. In this work, we propose to study the impact of two geometries (sharp and chamfered LEs) of these components, as well as their misalignments on local hot spot generation, by means of embedded diagnostics (TC/FBG), and a submillimeter infrared system (~0.1 mm/pixel), whose emissivity varies with wavelength, and the temperature, but above all, the surface state of the component, which evolves under plasma exposure, during the experimental campaigns. The divertor Langmuir probes measure the plasma temperature, and thus estimate the ion Larmor radius that may play a role in the local heat flux distribution around poloidal and toroidal edges. The results presented in this thesis, confirming the modelling predictions by experimental measurements, support the final decision by ITER to include 0.5 mm toroidal beveling of monoblocks on the vertical divertor targets to protect poloidal leading edges from excessive heat flux
Asghar, Jawaria. "Jointly Ego Motion and Road Geometry Estimation for Advanced Driver Assistance Systems." Thesis, Linköpings universitet, Reglerteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-179491.
Mehmood, Muhammad Owais. "Détection de personnes pour des systèmes de videosurveillance multi-caméra intelligents." Thesis, Ecole centrale de Lille, 2015. http://www.theses.fr/2015ECLI0016/document.
People detection is a well-studied open challenge in the field of Computer Vision with applications such as in the visual surveillance systems. Monocular detectors have limited ability to handle occlusion, clutter, scale, density. Ubiquitous presence of cameras and computational resources fuel the development of multi-camera detection systems. In this thesis, we study the multi-camera people detection; specifically, the use of multi-view probabilistic occupancy maps based on the camera calibration. Occupancy maps allow multi-view geometric fusion of several camera views. Detection with such maps create several false detections and we study this phenomenon: ghost pruning. Further, we propose two novel techniques in order to improve multi-view detection based on: (a) kernel deconvolution, and (b) occupancy shape modeling. We perform non-temporal, multi-view reasoning in occupancy maps to recover accurate positions of people in challenging conditions such as of occlusion, clutter, lighting, and camera variations. We show improvements in people detections across three challenging datasets for visual surveillance including comparison with state-of-the-art techniques. We show the application of this work in exigent transportation scenarios i.e. people detection for surveillance at a train station and at an airport
Zhang, Ligang. "Towards spontaneous facial expression recognition in real-world video." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/53199/1/Ligang_Zhang_Thesis.pdf.
Laribi, Elias. "Modélisation numérique de l'impact de la géométrie magnétique sur le plasma de bord des tokamaks." Electronic Thesis or Diss., Aix-Marseille, 2021. http://www.theses.fr/2021AIXM0298.
This phD work has shown that, in a limiter configuration, the elongation of magnetic surfaces has a stabilizing effect with respect to the edge plasma turbulence. This leads to a reduction of the edge plasma width when the elongation increases. Regarding triangularity, this phD work revealed that its effects on the edge plasma were weaker than those of elongation. A better understanding of these trends has been possible thanks to a theoretical work on a simplified interchange model. This work has also revealed the importance of the magnetic field spatial variability on the poloidal size of turbulent structures and therefore on the radial turbulent fluxes. In a second step, the study of a divertor configuration with one X point has shown that the the magnetic field spatial variability was so important that it could be one of the reasons that explain the enhancement of the low field side ballooned nature of edge plasma turbulence in a divertor geometry. Still concerning the divertor geometry, this phD also revealed that the internal material receives more heat compared to the external material when the toroidal magnetic field is oriented in the direct direction (= magnetic drift of the ions pointing towards the X point). A possible explanation of this observation is the existence of a significant plasma circulation from the low field side to the high field side at the X point that we observed in this configuration. Finally, we were able to confirm that one way to improve this heat flux distribution on the walls was to merge two X points perfectly (= ideal snowflake proposed in 2007 by Ryutov and Sukhanovsky)
Crambes, Christine. "Deux approches du processus de fusion (a) etude experimentale de la fusion d'un bloc de solide sous une geometrie verticale (b) etude du volcanisme tibetain." Paris 7, 2000. http://www.theses.fr/2000PA077050.
Hasting, William. "Geometric Effects of Free-Floating Technique on Alloy 718 Parts Produced via Laser-Powder Bed Fusion." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613751580039925.
Molinier, Rémi. "Cohomology with twisted coefficients of the geometric realization of linking systems." Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCD021/document.
The aim of this work is to study the cohomology with twisted coefficients of the geometric realization of linking systems. More precisely, if (S, Ƒ, ℒ) is a p-local finite group, we work on the cohomology H*(\ℒ\, M) of the geometric realization of ℒ with coefficients in a Z(p)[π₁(\ℒ\)]-module M and its links with the Ƒᶜ-stables H*(Ƒᶜ, M) ⊆ H*(S, M) trough the inclusion of BS in \ℒ\. After we give the definition of Ƒᶜ-stable elements , we study the endomorphism of H*(S, M) induced by an Fc-characteristic (S, S)-biset and we show that, if the action is nilpotent- and we assume an hypothesis, we have a natural isomorphism H*(\ℒ\, M) ≌ H* (Fᶜ;M). Secondly, we look at p-solvable actions of π₁(\ℒ\) on M through the notion of p-local subgroups of index a power of p or prime to p. If the action factors through a p'-group, we show that there si also a natural isomorphism. We then work on extending this to any-p-solvable action and we get some positive answer then the p-local finite groupis realizable. Theses leads to the conjecture that it is true for any-p-local finite group and any-p-solvable actions. We also give some tools to study this conjecture on examples. We look at products of p-local finite groups with Kunneth Formula and linking system which can be decomposed in a way which behaves well with Mayer-Vietoris long exact sequence. Finally, we study essential subgroups of wreath productsby Cp. We finish with some examples which illustrate that, in general, we cannot hope an isomorphism between H*(\ℒ\, M) and H*(Ƒᶜ, M)
Benea, Claudia-Roxana. "Morphing Structures : An exploration of the fusion between marbled coating and triaxial weave." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-15746.
Godineau, Kévin. "Optimisation du pilotage de chaînes opto-mécaniques pour l'exécution de trajectoires en fabrication additive par fusion laser sur lit de poudre." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN019.
In metal additive manufacturing by laser powder bed fusion, the geometry and mechanical characteristics of the produced parts are generated during the manufacturing process. These two aspects are greatly influenced by the laser spot trajectories, and by the control of the energy provided to the powder locally. The numerical control system, whose purpose is to generate instructions to be sent to actuators, has therefore a significant impact on the quality of the parts produced.This work proposes to study the local impact of the operations carried out in the numerical control on both the trajectories executed and the energy provided to the material. In the literature, few studies have addressed these aspects in additive manufacturing. For this reason, an experimental platform is implemented and used to analyze and better understand the operations currently implemented in industrial numerical controls.First, a mathematical model representative of the machine geometry is established. This model converts the laser spot trajectories into instructions for actuators. The model developed is used to improve the calibration step of the machines. Once the system is calibrated, the instructions sent to the actuators are studied. The various processes carried out in the industrial numerical control are analysed, limitations are highlighted and several proposals for improvements are implemented. All these developments are then used to precisely control the energy supplied to the material in the case of certain trajectories adapted to the process. The scientific developments proposed in these works are all validated experimentally on an additive manufacturing machine or on the test bench developed. The work carried out makes it possible to envisage many perspectives concerning the improvement of the treatments carried out inside the numerical control in additive manufacturing
Arezki, Yassir. "Algorithmes de références 'robustes' pour la métrologie dimensionnelle des surfaces asphériques et des surfaces complexes en optique." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN058.
Aspheres and freeform surfaces are a very challenging class of optical elements. Their application has grown considerably in the last few years in imaging systems, astronomy, lithography, etc. The metrology for aspheres is very challenging, because of the high dynamic range of the acquired information and the traceability to the SI unit meter. Metrology should make use of the infinite norm; (Minimum Zone Method or Min-Max method) to calculate the envelope enclosing the points in the dataset by minimizing the difference between the maximum deviation and the minimum deviation between the surface and the dataset. This method grows in complexity as the number of points in the dataset increases, and the involved algorithms are non-deterministic. Despite the fact that this method works for simple geometries (lines, planes, circles, cylinders, cones and spheres) it is still a major challenge when used on complex geometries (asphere and freeform surfaces). Therefore, the main objective is to address this key challenge about the development of Min-Max fitting algorithms for both aspherical and freeform surfaces as well as least squares fitting algorithms, in order to provide robust reference algorithms for the large community involved in this domain. The reference algorithms to be developed should be evaluated and validated on several reference data (softgauges) that will be generated using reference data generators
Pal, Anibrata. "Multi-objective optimization in learn to pre-compute evidence fusion to obtain high quality compressed web search indexes." Universidade Federal do Amazonas, 2016. http://tede.ufam.edu.br/handle/tede/5128.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The world of information retrieval revolves around web search engines. Text search engines are one of the most important source for routing information. The web search engines index huge volumes of data and handles billions of documents. The learn to rank methods have been adopted in the recent past to generate high quality answers for the search engines. The ultimate goal of these systems are to provide high quality results and, at the same time, reduce the computational time for query processing. Drawing direct correlation from the aforementioned fact; reading from smaller or compact indexes always accelerate data read or in other words, reduce computational time during query processing. In this thesis we study about using learning to rank method to not only produce high quality ranking of search results, but also to optimize another important aspect of search systems, the compression achieved in their indexes. We show that it is possible to achieve impressive gains in search engine index compression with virtually no loss in the final quality of results by using simple, yet effective, multi objective optimization techniques in the learning process. We also used basic pruning techniques to find out the impact of pruning in the compression of indexes. In our best approach, we were able to achieve more than 40% compression of the existing index, while keeping the quality of results at par with methods that disregard compression.
Máquinas de busca web para a web indexam grandes volumes de dados, lidando com coleções que muitas vezes são compostas por dezenas de bilhões de documentos. Métodos aprendizagem de máquina têm sido adotados para gerar as respostas de alta qualidade nesses sistemas e, mais recentemente, há métodos de aprendizagem de máquina propostos para a fusão de evidências durante o processo de indexação das bases de dados. Estes métodos servem então não somente para melhorar a qualidade de respostas em sistemas de busca, mas também para reduzir custos de processamento de consultas. O único método de fusão de evidências em tempo de indexação proposto na literatura tem como foco exclusivamente o aprendizado de funções de fusão de evidências que gerem bons resultados durante o processamento de consulta, buscando otimizar este único objetivo no processo de aprendizagem. O presente trabalho apresenta uma proposta onde utiliza-se o método de aprendizagem com múltiplos objetivos, visando otimizar, ao mesmo tempo, tanto a qualidade de respostas produzidas quando o grau de compressão do índice produzido pela fusão de rankings. Os resultados apresentados indicam que a adoção de um processo de aprendizagem com múltiplos objetivos permite que se obtenha melhora significativa na compressão dos índices produzidos sem que haja perda significativa na qualidade final do ranking produzido pelo sistema.
Miranda, Marilene Moussa. "A experiência norte-americana de fusão da aritmética, álgebra e geometria e sua apropriação pela educação matemática brasileira." Pontifícia Universidade Católica de São Paulo, 2003. https://tede2.pucsp.br/handle/handle/11170.
This dissertation is a study on the North American experiment of merging subjects such as Arithmetic, Algebra and Geometry, and the influence of this experiment over the Mathematic education in Brazil. We have analyzed a few changes occurred in the secondary school in North America between 1890 and 1930, and also how Professor Euclides Roxo used that initiative as he presented his proposal for a change in the curriculum of the D. Pedro II Secondary School, creating the subject of Mathematics. We finally make a comparative analyzes of the proposals on the teaching of Mathematics both in Brazil and in the USA. In our conclusion, we justify the lack of success of both proposals, in two different contexts, whose purpose was to merge the different branches of Mathematic for teaching
O trabalho estuda a experiência norte-americana de fusão da Aritmética, Álgebra e Geometria e sua influência na Educação Matemática Brasileira. São analisadas algumas modificações ocorridas no ensino secundário norte-americano, durante o período compreendido entre 1890 a 1930, e o modo como o professor Euclides Roxo apropria-se dessas iniciativas ao apresentar sua proposta de alteração na seriação do curso secundário do Colégio Pedro II criando a disciplina Matemática. Ao final é feito um estudo comparativo das propostas para o ensino de Matemática nos EUA e no Brasil concluindo por justificar o fracasso dessas duas reformas, em contextos diferentes, que visavam fundir os ramos matemáticos para o ensino
Ordoñez, Mosquera Miguel Eduardo. "Aplicação da fusão de dados na medição de superfícies regulares e forma livre." reponame:Repositório Institucional da UnB, 2012. http://repositorio.unb.br/handle/10482/12559.
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A reconstrução tridimensional é uma tarefa que envolve diferentes etapas como definição da estratégia de medição, aquisição de dados, registro, implementação, modelagem Computer-Aided Design (CAD) e ajuste e determinação da incerteza de medição. Nesta tarefa, as relações de conexão entre os pontos (coordenadas x, y e z) que compõem a amostra não são conhecidas, principalmente quando a nuvem de pontos está contaminada com interferências desconhecidas, inerentes ao processo de medição. Um aspecto que influencia a qualidade dos dados é a calibração do instrumento de medição, sendo que a determinação da incerteza permite estabelecer a qualidade do modelo representativo do objeto. O emprego de mais de um instrumento para a coleta dos dados de coordenadas permite obter uma precisão maior do modelo através de medições localizadas com instrumento de maior resolução e menor incerteza. Porém, isto exige uma atenção especial ao procedimento de fusão dos dados, antes do ajuste do modelo CAD. Esta dissertação aborda a técnica para modelar superfícies de objetos tridimensionais e executar o procedimento de fusão dos dados obtidos com dois diferentes instrumentos de medição. A avaliação do modelo foi feito através da determinação da incerteza de medição, associada às diferentes fontes de erros neste processo. _______________________________________________________________________________________ ABSTRACT
Three-dimensional reconstruction is a task that involves different steps as the definition of measurement strategy, data acquisition, registration, implementation, modeling Computer-Aided Design (CAD), adjustment and determination of measurement uncertainty. In this task, the relations among data points (coordinates x, y,z) in the sample are not known, especially when the point cloud is contaminated with noise, inherent to the measurement process. One aspect that influences the quality of data is the calibration of the measuring instrument and the determination of the uncertainty allows the establishment of the quality of the model representing the object. The use of more than one instrument to coordinate data capture allows the increase of the model precision, as in the case of localized measurements with a higher resolution and reduced uncertainty instrument. However, this requires special attention to the data fusion procedure, before the adjustment of the CAD model. This work discusses the technique for three-dimensional modeling of object surfaces and the procedure for merging the data obtained with two different measuring instruments. The evaluation of the model was made by determining the uncertainty of the measurement, associated to the various sources of error in this process.
Chi, Wenjun. "MRI image analysis for abdominal and pelvic endometriosis." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:27efaa89-85cd-4f8b-ab67-b786986c42e3.
"The Fusion of Multimodal Brain Imaging Data from Geometry Perspectives." Doctoral diss., 2020. http://hdl.handle.net/2286/R.I.62817.
Dissertation/Thesis
Doctoral Dissertation Computer Science 2020
Zangi, Ronen. "Phase transitions in a confined geometry /." 1999. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:9943142.
"Binocular geometry and camera motion directly from normal flows." Thesis, 2009. http://library.cuhk.edu.hk/record=b6074789.
On determining the ego-motion of a camera, there have been many previous works as well. However, again, most of the works require to track distinct features in the image stream or to infer the full optical flow field from the normal flow field. Different from the traditional works, utilizing no motion correspondence nor the epipolar geometry, a new method is developed that operates again on the normal flow data directly. The method has a number of features. It can employ the use of every normal flow data, thus requiring less texture from the image scene. A novel formulation of what the normal flow direction at an image position has to offer on the camera motion is given, and this formulation allows a locus of the possible camera motion be outlined from every data point. With enough data points or normal flows over the image domain, a simple voting scheme would allow the various loci intersect and pinpoint the camera motion.
On determining the relative geometry of two cameras, there already exist a number of calibration techniques in the literature. They are based on the presence of either some specific calibration objects in the imaged scene, or a portion of the scene that is observable by both cameras. However, in active vision, because of the "active" nature of the cameras, it could happen that a camera pair do not share much or anything in common in their visual fields. In the first part of this thesis, we propose a new solution method to the problem. The method demands image data under a rigid motion of the camera pair, but unlike the existing motion correspondence-based calibration methods it does not estimate the optical flows or motion correspondences explicitly. Instead it estimates the inter-camera geometry from the monocular normal flows. Moreover, we propose a strategy on selecting optimal groups of normal flow vectors to improve the accuracy and efficiency of the estimation.
The relative motion between a camera and the imaged environment generally induces a flow field in the image stream captured by the camera. The flow field, which is about motion correspondences of the various image positions over the image frames, is referred to as the optical flows in the literature. If the optical flow field of every camera can be made available, the motion of a camera can be readily determined, and so can the relative geometry of two cameras. However, due to the well-known aperture problem, directly observable at any image position is generally not the full optical flow, but only the component of it that is normal to the iso-brightness contour of the intensity profile at the position. The component is widely referred to as the normal flow. It is not impossible to infer the full flow field from the normal flow field, but then it requires some specific assumptions about the imaged scene, like it is smooth almost everywhere etc.
This thesis aims at exploring how the above two fundamental tasks can be tackled by operating on the normal flow field directly. The objective is, without the full flow inferred explicitly in the process, and in turn no specific assumption made about the imaged scene, the developed methods can be applicable to a wider set of scenes. The thesis consists of two parts. The first part is about how the inter-camera geometry of two cameras can be determined from the two monocular normal flow fields. The second part is about how a camera's ego-motion can be determined by examining only the normal flows the camera observes.
We have tested the methods on both synthetic image data and real image sequences. Experimental results show that the developed methods are effective in determining inter-camera geometry and camera motion from normal flow fields.
Yuan, Ding.
Adviser: Ronald Chung.
Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: .
Thesis submitted in: October 2008.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2009.
Includes bibliographical references (leaves 121-131).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts in English and Chinese.
School code: 1307.
Mishra, Saurabh. "Tailoring weld geometry and composition in fusion welding through convective mass transfer calculations." 2006. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1208/index.html.
Lin, Cheng Xue, and 林承學. "Biomechanical Study of Solid Pedicle Screws on Spinal Fusion Surgery: Effects of Screw Geometry and Bone Quality." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/uguy9n.
長庚大學
醫療機電工程研究所
104
Background: Robust fixation of pedicle screws remains challenge for Orthopedist. Previous studies have demonstrated that numerous factors such as screw types (perforation or expansion), screw designs (thread, thread pitch, shaft diameter) are related to screw anchoring strength. However, literatures addressing the influence of screw design including outer/inner diameter shape (cylindrical/ cylindrical, cylindrical/conical, conical/conical) and thread type (square or V-thread) on the screw fixation strength is lacking. Therefore, the aim of this study is to explore the mechanical performance of the aforementioned screws in two-fold: (1) Effect of bone quality on screw fixation strength; (2) Association among pilot-hole size, screw insertion torque and screw fixation strength. Methods: Two types of synthetic bones (test blocks, 20 pcf and 30 pcf) were used to mimic human vertebral bones with different densities. Six kinds of pedicle screws were recruited. These include three different outer diameter shape/core diameter shape (conical/conical, cylindrical/conical and cylindrical/cylindrical) equipped with two different thread types (square or V-thread). Each screw was inserted into test blocks prepared with different diameters of pilot holes (2.7mm, 3.2mm and 3.7mm). During screw insertion, the insertion torque was measured simultaneously using a torque gauge. Following specimens preparation, screw pullout tests were then conducted using MTS testing machine. Results: (1). Regardless of bone quality, V-shape groups have higher pullout strength as compared to square-shape groups. Additionally, V-type pedicle screws with cylindrical/conical shape exhibited the highest pullout strength among groups (p < 0.05). (2). No significant association was found between thread type (V- or Square) and insertion torque. (3). For screw with identical thread type (V- or Square), screws with a smaller pilot hole let to an increase in insertion torque and pullout strength. (4). Enlargement of pilot hole significantly reduced pullout strength, particularly for screw with a 3.3 mm pilot hole. Conclusion: We concluded that V-type pedicle screws with cylindrical/conical shape presented the most robust fixation under circumstance of screws prepared with higher bone density and smaller pilot hole.
Tseng, Chin-Yuan, and 曾勁源. "Geometric Constraint Image Feature Tracking and Sensor Fusion Technique with Visual-IMU Information." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/97924361167654124183.
國立交通大學
電控工程研究所
103
This dissertation includes three kinds of applications with visual inertial sensor information in 1) image feature tracking, 2) anchor location estimation in wireless sensor networks (WSN), and 3) visual-IMU odometer. In image feature tracking, the epipolar geometry is an important constraint to limit the feature moving area. In this dissertation, the following property is explored: the optical flow vector of the static feature point lies on the epipolar line of cameras with pure translation. For monocular camera motion, the epipolar line then becomes a scan line for feature searching. A constraint feature selection method by using the direction of the epipolar line to filter unstable feature points is proposed. The geometric constraints have no relation to the scene structure or the ratio of the inlier/outlier feature points. To realize the proposed idea, an inertial measurement unit (IMU) is needed to give the rotational information among camera poses. We propose an IMU aided geometric constraint (IGC) feature tracking algorithm. The IGC feature tracking algorithm provides a strength geometric constraint during the feature tracking procedure, and the tracking complexity is . Beyond the geometric constraints, the verification of the tracking result becomes very simple. We propose two kinds of sensor fusion algorithm in anchor node location estimation in wireless sensor network and visual-IMU odometer by using IMU-camera device. In anchor node location estimation, we combined camera trajectory estimation algorithm with a human walking model to realize a scaled visual odometry. Instead of double integration of acceleration, the scale factor from the walking speed estimation uses only the acceleration information of the body. The loosely-coupled approach fuses the RSSI data and attitude of VO to provide an accurate motion trajectory and anchor node locations simultaneously. In visual-IMU odometer, the proposed method uses multi-state constraint Kalman-filter and geometrical constraints of the trifocal tensor and pure translation geometry. The multi-state constraint Kalman filter can fuse the information from the camera and IMU, and the trifocal tensor and pure translation geometric constraints can provide a reliable static feature selection without scene reconstruction. The experiment of the feature tracking includes the latent aperture problem, repeated pattern problem and low texture problem, and also concludes the trajectory estimation results and analysis of locating anchors in WSN and visual-IMU odometer. The experiment results show the effectiveness and robustness of the proposed method.
Macedo, Beatriz Brites. "Metal based additive manufacturing: Characterization of geometric distortion of powder bed fusion parts after heat treatment." Master's thesis, 2019. https://hdl.handle.net/10216/119269.
"Fusing scattered images with multiresolution point-based model." 2003. http://library.cuhk.edu.hk/record=b5891582.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.
Includes bibliographical references (leaves 81-86).
Abstracts in English and Chinese.
Abstract --- p.i
Acknowledgments --- p.iii
Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Motivation --- p.1
Chapter 1.2 --- Contribution --- p.3
Chapter 1.3 --- Previous Work --- p.5
Chapter 1.4 --- Thesis Organization --- p.9
Chapter 2 --- Overview --- p.10
Chapter 3 --- Data Acquisition --- p.14
Chapter 3.1 --- Acquiring the Surface Model --- p.14
Chapter 3.2 --- Camera Calibration --- p.16
Chapter 3.3 --- Capturing Image with Camera Pose --- p.18
Chapter 3.3.1 --- Fastrack --- p.19
Chapter 3.3.2 --- Tracking the Camera Pose --- p.21
Chapter 3.3.3 --- Calibrating the Tracking System --- p.23
Chapter 3.4 --- Summary --- p.32
Chapter 4 --- Data Fusion --- p.33
Chapter 4.1 --- Converting Surface Model to Point-Based Model --- p.33
Chapter 4.2 --- Registering the Radiance Values onto the Point-Based Model --- p.36
Chapter 4.3 --- Scattered Data Fitting --- p.40
Chapter 4.3.1 --- Spherical Delaunay Triangulation --- p.41
Chapter 4.3.2 --- Hierarchical Spherical Triangulation --- p.46
Chapter 4.3.3 --- Interpolation --- p.49
Chapter 4.4 --- Data Compression --- p.50
Chapter 4.5 --- Summary --- p.52
Chapter 5 --- Multiresolution Point-Based Representation and Rendering --- p.53
Chapter 5.1 --- Multiresolution Point-Based Representation --- p.55
Chapter 5.1.1 --- Construction --- p.57
Chapter 5.2 --- Rendering --- p.62
Chapter 5.2.1 --- Culling --- p.63
Chapter 5.2.2 --- Drawing the Node --- p.66
Chapter 5.3 --- Summary --- p.68
Chapter 6 --- Experimental Results --- p.69
Chapter 6.1 --- Tested Objects --- p.69
Chapter 6.2 --- Evaluation --- p.70
Chapter 6.3 --- Summary --- p.78
Chapter 7 --- Conclusion --- p.79
Chapter 7.1 --- Summary --- p.79
Chapter 7.2 --- Future Direction --- p.80
Bibliography --- p.81
Růžička, Jakub. "Automatizované odvození geometrie jízdních pruhů na základě leteckých snímků a existujících prostorových dat." Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-414961.
Cheng, Chieh-Chung, and 鄭傑中. "Geometric Inference of Building Roof Reconstruction by Fusing LiDAR Data Set and Aerial Photographs." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/94991780336278440361.
國立臺灣大學
土木工程學研究所
94
The advent of LiDAR technique has opened up many possibilities for the purpose of object/surface reconstruction. The direct geo-referencing of 3-D laser point towards surface or terrain apparently outperforms photogrammetric method by employing at least two overlapping images in the data acquisition favor. It is, however, still inevitable to see some weaker characteristics of LiDAR system as compared to photogrammetric relatively high ground resolution and richer radiometric content revealed from the images. Therefore, fusion of above two data sets by utilizing mutual strengths for the purpose of reconstructing spatial information can be certainly optimistic and foreseen. The designed steps of building roof reconstruction are carried out by: (1). Hypothesizing 3-D building boundaries from LiDAR data set by edge detection; (2). Constructing the topological relationship of 3-D building boundaries; (3). Back-projecting hypothesized 3-D building boundaries onto the associated photos; (4). Validation of building boundaries by imposing 3-D geometric inference among intersected conjugate lines of candidates found in the images; (5). Merging and adjusting building boundaries. The results show that the proposed system offers more robust and satisfactory building reconstruction result as compared to the situation when only single data set is attempted.
Cai, Chenghui. "Information-driven Sensor Path Planning and the Treasure Hunt Problem." Diss., 2008. http://hdl.handle.net/10161/626.