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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.
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Inertial Electrostatic Confinement (IEC) fusion is a technique that uses electrostatic fields to confine and heat ions in order to achieve nuclear fusion. This is achieved by using a metal grid as the cathode to create the confining electrostatic well. There have been unpublished suggestions that the materials and geometry of the cathode have an effect on the fusion rate. A systematic experimental study is carried out on a range of non-standard cathode geometries and materials in an IEC fusion device under low energy conditions to challenge the commonly accepted notion that a more highly transparent grid is the most efficient means of fusion neutron production. A number of hollow cathode geometries were exposed to a range of different pressures, voltages, and currents, which were compared to an IEC grid under the same conditions. The cathode surface temperature and ion energy distribution in the plasma were used to correlate the fusion rate associated with the temperature and plasma properties. It was found that the hollow cathodes operating under the abnormal discharge conditions produced more neutrons than an IEC grid. A model using ambipolar diffusion and sheath terms was developed. A study into the material dependence of the cathodes was performed using stainless steel as the control group. Graphite was found to produce an order of magnitude more neutrons than stainless steel. A model was presented that showed a qualitative trend for all metallic samples that correlated with the experimental results. However the anomalous results from graphite proved to be more elusive. Finally, a cathode that combined both the most efficient geometry and material was studied. The graphite biconical cathode was found to have a higher fusion rate than the sum of its parts. This study represents the first of its kind focusing on the effects of material and cathode geometry under low energy discharge conditions on the neutron production rate.
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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.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>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.<br>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.
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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.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2005.<br>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.
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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.
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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.
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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.
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Existing residential and small commercial buildings now represent the greatest opportunity to improve building energy efficiency. Building energy simulation analysis is becoming increasingly important because the analysis results can assist the decision makers to make decisions on improving building energy efficiency and reducing environmental impacts. However, manually measuring as-is conditions of building envelops including geometry and thermal value is still a labor-intensive, costly, and slow process. Thus, the primary objective of this research was to automatically collect and extract the as-is geometry and thermal data of the building envelope components and create a gbXML-based building geometry model.
In the proposed methodology, a rapid and low-cost data collection hardware system was designed by integrating 3D laser scanners and an infrared (IR) camera. Secondly, several algorithms were created to automatically recognize various components of building envelope as objects from collected raw data. The extracted 3D semantic geometric model was then automatically saved as an industry standard file format for data interoperability. The feasibility of the proposed method was validated through three case studies.
The contributions of this research include 1) a customized low-cost hybrid data collection system development to fuse various data into a thermal point cloud; 2) an automatic method of extracting building envelope components and its geometry data to generate gbXML-based building geometry model. The broader impacts of this research are that it could offer a new way to collect as is building data without impeding occupants’ daily life, and provide an easier way for laypeople to understand the energy performance of their buildings via 3D thermal point cloud visualization.
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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.
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Une compréhension profonde du transport du plasma au bord d'un réacteur à fusion par confinement magnétique est obligatoire pour gérer l'extraction de puissance. Dans les dispositifs de fusion de nouvelle génération, des limites technologiques contraignent le flux de chaleur maximal au divertor. Pour une puissance d'échappement donnée le flux de chaleur maximal est déterminé par l'amplitude de l'empreinte du plasma au mur. Les profils de flux de chaleur au divertor peuvent être paramétrés par deux échelles de longueur du transport. Nous remettons en question l'interprétation actuelle de ces deux échelles de longueur en étudiant l'impact de la géométrie du divertor sur l'échappement. En particulier, un élargissement des profils de flux de chaleur avec la longueur de la jambe du divertor externe est diagnostiqué. Des efforts de modélisation ont montré que les simulations diffusives reproduisent les profils expérimentaux de flux de chaleur pour les plasmas à jambes courtes. Inversement, l'étalement du flux de chaleur pour une longe jambe du divertor est reproduit par un modèle turbulent, soulignant l'importance de la turbulence aussi dans le divertor. Ces résultats remettent en question l'interprétation de la largeur du flux de chaleur comme grandeur liée a la main SOL uniquement. Les configurations magnétiques avec une longe jambe du divertor mettent en évidence l'importance du transport asymétrique dans le divertor. Nous concluons que le transport dans la main SOL et celui dans le divertor ne sont pas à découpler et nous soulignons l'importance de la géométrie magnétique sur le transport turbulent avec l'avantage potentiel d'un inattendu étalement du dépôt de puissance<br>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
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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.
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Une compréhension profonde du transport du plasma au bord d'un réacteur à fusion par confinement magnétique est obligatoire pour gérer l'extraction de puissance. Dans les dispositifs de fusion de nouvelle génération, des limites technologiques contraignent le flux de chaleur maximal au divertor. Pour une puissance d'échappement donnée le flux de chaleur maximal est déterminé par l'amplitude de l'empreinte du plasma au mur. Les profils de flux de chaleur au divertor peuvent être paramétrés par deux échelles de longueur du transport. Nous remettons en question l'interprétation actuelle de ces deux échelles de longueur en étudiant l'impact de la géométrie du divertor sur l'échappement. En particulier, un élargissement des profils de flux de chaleur avec la longueur de la jambe du divertor externe est diagnostiqué. Des efforts de modélisation ont montré que les simulations diffusives reproduisent les profils expérimentaux de flux de chaleur pour les plasmas à jambes courtes. Inversement, l'étalement du flux de chaleur pour une longe jambe du divertor est reproduit par un modèle turbulent, soulignant l'importance de la turbulence aussi dans le divertor. Ces résultats remettent en question l'interprétation de la largeur du flux de chaleur comme grandeur liée a la main SOL uniquement. Les configurations magnétiques avec une longe jambe du divertor mettent en évidence l'importance du transport asymétrique dans le divertor. Nous concluons que le transport dans la main SOL et celui dans le divertor ne sont pas à découpler et nous soulignons l'importance de la géométrie magnétique sur le transport turbulent avec l'avantage potentiel d'un inattendu étalement du dépôt de puissance<br>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
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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.
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This study retrofitted a Diagnostic Classification Model (DCM) known as the Fusion model onto non-diagnostic test data from of the University of Chicago School Mathematics Project (UCSMP) Algebra and Geometry Readiness test post-test used with Transition Mathematics (Third Edition, Field-Trial Version). The test contained 24 multiple-choice middle school math items, and was originally given to 95 advanced 6th grade and 293 7th grade students. The use of these test answers for this study was an attempt to show that by using cognitive diagnostic analysis techniques on test items not constructed for that purpose, highly predictable multidimensional cognitive attribute profiles for each test taker could be obtained. These profiles delineated whether a given test taker was a master or non-master for each attribute measured by the test, thus allowing detailed diagnostic feedback to be disseminated to both the test takers and their teachers.
The full version of the non-compensatory Fusion model, specifically, along with the Arpeggio software package, was used to estimate test taker profiles on each of the four cognitive attributes found to be intrinsic to the items on this test, because it handled both slips and guesses by test takers and accounted for residual skills not defined by the four attributes and twenty-four items in the Q-matrix. The attributes, one or more of which was needed to correctly answer an item, were defined as: Skills— those procedures that students should master with fluency; e.g., multiplying positive and negative numbers; Properties—which deal with the principles underlying the mathematics concepts being studied, such as being able to recognize and use the Repeated-Addition Property of Multiplication; Uses—which deal with applications of mathematics in real situations ranging from routine "word problems" to the development and use of mathematical models, like finding unknowns in real situations involving multiplication; and, Representations—which deal with pictures, graphs, or objects that illustrate concepts.
Ultimately, a Q-matrix was developed from the rating of four content experts, with the attributes needed to answer each item clearly delineated. A validation of this Q-matrix was obtained from the Fusion model Arpeggio application to the data as test taker profiles showed which attributes were mastered by each test taker and which weren’t. Masters of the attributes needed to be acquired to successfully answer a test item had a proportion-correct difference from non-masters of .44, on average. Regression analysis produced an R-squared of .89 for the prediction of total scores on the test items by the attribute mastery probabilities obtained from the Fusion model with the final Q-matrix. Limitations of the study are discussed, along with reasons for the significance of the study.
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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.
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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.
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L'augmentation des données dans divers domaines présente un besoin essentiel de techniques avancées pour fusionner et interpréter ces informations. Avec une emphase particulière sur la compilation de données géospatiales, cette intégration est cruciale pour débloquer de nouvelles perspectives à partir des données géographiques, améliorant notre capacité à cartographier et analyser les tendances qui s'étendent à travers différents lieux et environnements avec plus d'authenticité et de fiabilité. Les techniques existantes ont progressé dans l'adresse de la fusion des données ; cependant, des défis persistent dans la fusion et l'harmonisation des données de différentes sources, échelles et modalités. Cette recherche présente une enquête complète sur les défis et les solutions dans l'alignement et la fusion des cartes vectorielles, se concentrant sur le développement de méthodes qui améliorent la précision et l'utilisabilité des données géospatiales. Nous avons exploré et développé trois méthodologies distinctes pour l'alignement des cartes vectorielles polygonales : ProximityAlign, qui excelle en précision dans les agencements urbains; l'Alignement Basé sur l'Apprentissage Profond du Flux Optique, remarquable pour son efficacité ; et l'Alignement Basé sur la Géométrie Épipolaire, efficace dans les contextes riches en données. De plus, notre étude s'est penchée sur l'alignement des cartes de géometries linéaires, soulignant l'importance d'un alignement précis et du transfert d'attributs des éléments, pointant vers le développement de bases de données géospatiales plus riches et plus informatives en adaptant l'approche ProximityAlign pour des géometries linéaires telles que les traces de failles et les réseaux routiers. L'aspect fusion de notre recherche a introduit un pipeline sophistiqué pour fusionner des géométries polygonales en se basant sur le partitionnement d'espace, l'optimisation non convexe de la structure de données de graphes et les opérations géométriques pour produire une carte fusionnée fiable qui harmonise les cartes vectorielles en entrée, en maintenant leur intégrité géométrique et topologique. En pratique, le cadre développé a le potentiel d'améliorer la qualité et l'utilisabilité des données géospatiales intégrées, bénéficiant à diverses applications telles que la planification urbaine, la surveillance environnementale et la gestion des catastrophes. Cette étude avance non seulement la compréhension théorique dans le domaine mais fournit également une base solide pour des applications pratiques dans la gestion et l'interprétation de grands ensembles de données géospatiales<br>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
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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.
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There is growing interest in using additive manufacturing for various alloy systems and industrial applications. However, existing process development and part qualification techniques, both involve extensive experimentation-based procedures which are expensive and time-consuming. Recent developments in understanding the process control show promise toward the efforts to address these challenges. The current research uses the process mapping approach to achieve control of melt pool geometry and microstructure in different alloy systems, in addition to location specific control of microstructure in an additively manufactured part. Specifically, results demonstrate three levels of microstructure control, starting with the prior beta grain size control in Ti-6Al-4V, followed by cell (solidification structure) spacing control in AlSi10Mg, and ending with texture control in Inconel 718. Additionally, a prediction framework has been presented, that can be used to enable a preliminary understanding of melt pool geometry for different materials and process conditions with minimal experimentation. Overall, the work presented in this thesis has the potential to reduce the process development and part qualification time, enabling the wider adoption and use of additive manufacturing in industry.
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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.
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Cette thèse s’inscrit en support du projet ITER, sur l’étude du comportement thermique de prototypes de CFP dans des tokamaks supraconducteurs : EAST et WEST. Ces prototypes correspondent à un enchaînement de monoblocs de tungstène le long d’un tube de refroidissement, séparés par des interstices (0.5 mm), qui permet d’extraire la chaleur de ces composants. L’introduction de ces interstices entre monoblocs (toroïdaux) ou entre barres de monoblocs (poloïdaux), implique que le bord poloïdal peut être exposé aux lignes de champ avec une incidence quasi-normale. Un échauffement local très important est attendu sur une fine bande latérale de la surface supérieure de chaque monobloc, qui peut être accentué dans le cas où les composants sont désalignés. Nous proposons dans ce travail d’étudier l’impact de deux géométries (arête vive et chanfrein) de ces composants ainsi que de leurs désalignements sur la génération de points chauds locaux, à l’aide de diagnostics embarqués (TC/FBG), et d’une caméra infrarouge très haute résolution (~0.1 mm/pixel), dont l’émissivité varie en fonction de la longueur d’onde, de la température, et de l’état de surface, qui évolue au contact du plasma, lors des différentes campagnes expérimentales. Les sondes de Langmuir permettront de mesurer la température du plasma, et par conséquent d’estimer les rayons de Larmor des ions, qui pourront jouer un rôle important dans la distribution locale du flux de chaleur autour des bords poloïdaux et toroïdaux. Les travaux menés ici, montrent la cohérence entre les calculs prédictifs et les résultats expérimentaux et appuient la décision d'ITER de biseauter les MBs pour protéger leurs bords d'attaque<br>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
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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.
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For several years, there has been a remarkable increase in efforts to develop an autonomous car. Autonomous car systems combine various techniques of recognizing the environment with the help of the sensors and could drastically bring down the number of accidents on road by removing human conduct errors related to driver inattention and poor driving choices. In this research thesis, an algorithm for jointly ego-vehicle motion and road geometry estimation for Advanced Driver Assistance Systems (ADAS) is developed. The measurements are obtained from the inertial sensors, wheel speed sensors, steering wheel angle sensors, and camera. An Unscented Kalman Filter (UKF) is used for estimating the states of the non-linear system because UKF estimates the state in a simplified way without using complex computations. The proposed algorithm has been tested on a winding and straight road. The robustness and functioning of our algorithm have been demonstrated by conducting experiments involving the addition of noise to the measurements, reducing the process noise covariance matrix, and increasing the measurement noise covariance matrix and through these tests, we gained more trust in the working of our tracker. For evaluation, each estimated parameter has been compared with the reference signal which shows that the estimated signal matches the reference signal very well in both scenarios. We also compared our joint algorithm with individual ego-vehicle and road geometry algorithms. The results clearly show that better estimates are obtained from our algorithm when estimated jointly instead of estimating separately.
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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.
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La détection de personnes dans les vidéos est un défi bien connu du domaine de la vision par ordinateur avec un grand nombre d'applications telles que le développement de systèmes de surveillance visuels. Même si les détecteurs monoculaires sont plus simples à mettre en place, ils sont dans l’incapacité de gérer des scènes complexes avec des occultations, une grande densité de personnes ou des scènes avec beaucoup de profondeur de champ menant à une grande variabilité dans la taille des personnes. Dans cette thèse, nous étudions la détection de personnes multi-vues et notamment l'utilisation de cartes d'occupation probabilistes créées en fusionnant les différentes vues grâce à la connaissance de la géométrie du système. La détection à partir de ces cartes d'occupation amène cependant des fausses détections (appelées « fantômes ») dues aux différentes projections. Nous proposons deux nouvelles techniques afin de remédier à ce phénomène et améliorer la détection des personnes. La première utilise une déconvolution par un noyau dont la forme varie spatialement tandis que la seconde est basée sur un principe de validation d’hypothèse. Ces deux approches n'utilisent volontairement pas l'information temporelle qui pourra être réintroduite par la suite dans des algorithmes de suivi. Les deux approches ont été validées dans des conditions difficiles présentant des occultations, une densité de personnes plus ou moins élevée et de fortes variations dans les réponses colorimétriques des caméras. Une comparaison avec d'autres méthodes de l’état de l'art a également été menée sur trois bases de données publiques, validant les méthodes proposées pour la surveillance d'une gare et d'un aéroport<br>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
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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.
Full textAbstract:
Facial expression is an important channel of human social communication. Facial expression recognition (FER) aims to perceive and understand emotional states of humans based on information in the face. Building robust and high performance FER systems that can work in real-world video is still a challenging task, due to the various unpredictable facial variations and complicated exterior environmental conditions, as well as the difficulty of choosing a suitable type of feature descriptor for extracting discriminative facial information. Facial variations caused by factors such as pose, age, gender, race and occlusion, can exert profound influence on the robustness, while a suitable feature descriptor largely determines the performance.
Most present attention on FER has been paid to addressing variations in pose and illumination. No approach has been reported on handling face localization errors and relatively few on overcoming facial occlusions, although the significant impact of these two variations on the performance has been proved and highlighted in many previous studies. Many texture and geometric features have been previously proposed for FER. However, few comparison studies have been conducted to explore the performance differences between different features and examine the performance improvement arisen from fusion of texture and geometry, especially on data with spontaneous emotions. The majority of existing approaches are evaluated on databases with posed or induced facial expressions collected in laboratory environments, whereas little attention has been paid on recognizing naturalistic facial expressions on real-world data.
This thesis investigates techniques for building robust and high performance FER systems based on a number of established feature sets. It comprises of contributions towards three main objectives: (1) Robustness to face localization errors and facial occlusions. An approach is proposed to handle face localization errors and facial occlusions using Gabor based templates. Template extraction algorithms are designed to collect a pool of local template features and template matching is then performed to covert these templates into distances, which are robust to localization errors and occlusions.
(2) Improvement of performance through feature comparison, selection and fusion. A comparative framework is presented to compare the performance between different features and different feature selection algorithms, and examine the performance improvement arising from fusion of texture and geometry. The framework is evaluated for both discrete and dimensional expression recognition on spontaneous data.
(3) Evaluation of performance in the context of real-world applications. A system is selected and applied into discriminating posed versus spontaneous expressions and recognizing naturalistic facial expressions. A database is collected from real-world recordings and is used to explore feature differences between standard database images and real-world images, as well as between real-world images and real-world video frames.
The performance evaluations are based on the JAFFE, CK, Feedtum, NVIE, Semaine and self-collected QUT databases. The results demonstrate high robustness of the proposed approach to the simulated localization errors and occlusions. Texture and geometry have different contributions to the performance of discrete and dimensional expression recognition, as well as posed versus spontaneous emotion discrimination. These investigations provide useful insights into enhancing robustness and achieving high performance of FER systems, and putting them into real-world applications.
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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.
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Ce travail de thèse a montré que, dans une configuration limiteur, l’élongation des surfaces magnétiques a un effet stabilisant vis-à-vis de la turbulence dans le plasma de bord, ce qui conduit à une diminution de la largeur du plasma de bord quand l’élongation augmente. En ce qui concerne la triangularité, cette thèse a montré que ses effets sur le plasma de bord étaient plus faibles que ceux de l’élongation. Un travail théorique sur un modèle simplifié d'interchange a permis de comprendre ces tendances. Ces travaux ont également mis en lumière l'importance de la variabilité spatiale du champ magnétique sur la taille poloïdale des structures turbulentes et donc sur les flux turbulents radiaux qui en découlent. Dans un second temps, l’étude d’une configuration divertor à un point X nous a permis de voir que la variabilité spatiale du champ magnétique était telle qu'elle pourrait être une des causes du renforcement du caractère ballonné côté faible champ de la turbulence en géométrie divertor. Toujours en géométrie divertor, cette thèse a également montré que davantage de chaleur était déposée sur le matériau interne par rapport au matériau externe lorsque le champ magnétique toroïdal est orienté dans le sens direct (= dérive magnétique des ions vers le point X). Cela peut s'expliquer par l'existence d'une circulation importante de plasma du côté faible champ vers le côté fort champ au niveau du point X que l’on a observée dans cette configuration. Enfin, on a pu confirmer qu’une manière d’améliorer cette répartition des flux de chaleur sur les parois consiste à faire coïncider parfaitement deux points X (= snowflake idéal proposée en 2007 par Ryutov et Soukhanovski)<br>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)
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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.
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Cette these s'articule en deux parties et traite du processus de fusion. La partie a est une etude experimentale de mecanique des fluides, et la partie b est une etude geophysique du volcanisme tibetain. La partie a decrit l'experimentation de la fusion sous une geometrie verticale, dans laquelle est etudie le lien entre la fusion d'un bloc de solide soumis a un gradient vertical de temperature et la convection naturelle qui se developpe dans le fluide obtenu. Du fait de la non-adiabaticite sur les surfaces superieure et inferieure du bloc, trois regimes de fusion differents apparaissent : 1- domine par la conduction, 2- avec une seule echelle de convection (grande echelle), 3- avec deux echelles de convection (grande et petite echelle) et avec des corrugations. Le demarrage de la fusion pour ces trois regimes est controle par le parametre b qui depend des conditions de temperature aux limites du systeme. Pour des valeurs de b inferieures a 2. 6, il apparait un temps seuil t0 a partir duquel la convection de grande echelle se developpe. Dans la partie b, le volcanisme tibetain, qui s'est mis en place a la surface d'une croute epaissie et thermiquement perturbee suite a la collision inde-asie, semble resulter d'un melange entre les magmas mantellique et crustal. La fusion crustale est occasionnee par l'injection dans la croute de magmas provenant du manteau. Elle s'opere le long des parois de fissures verticales, ou dykes, remplies de magma. Les conditions aux limites thermiques des experiences sont similaires a celles de la croute tibetaine : un gradient thermique et un chauffage vertical. Pour la croute tibetaine, b est toujours inferieur a 2. 6. Un melange efficace entre deux magmas ne se fait qu'a partir du moment ou le magma crustal convecte naturellement. Or le temps seuil t0 calcule est inferieur au temps de remontee estime d'un seul dyke a travers la croute tibetaine, ainsi la convection peut se mettre en place et le melange peut se faire.
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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.
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Molinier, Rémi. "Cohomology with twisted coefficients of the geometric realization of linking systems." Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCD021/document.
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Nous présentons une étude de la cohomologie à coefficients tordus de la réalisation géométrique des systèmes de liaison. Plus précisément, si (S, Ƒ, ℒ) est un groupe fini p-local, nous travaillons sur la cohomologie H*(\ℒ\, M) de la réalisation géométrique de ℒ, avec un Z(p)[π₁(\ℒ\)]-module M en coefficients, et ses liens avec les éléments Fᶜ-stables H* (Ƒᶜ, M) ⊆ H*(S, M) à travers l’inclusion de BS dans \ℒ\. Après avoir donné la définition des éléments Ƒᶜ-stables, nous étudions l’endomorphisme de H*(S, M) induit par un (S, S)-bi-ensemble Ƒᶜ-caractéristique et nous montrons que sous certaine hypothèse et si l’action est nilpotent, alors on a un isomorphisme naturel H*(\ℒ\, M) ≌ H* (Ƒᶜ,M). Ensuite, nous regardons les actions p-résolubles à travers la notion de sous-groupe p-local d’index premier à p ou une puissance de p. Nous montrons que si l’action de π₁(\ℒ\) sur M se factorise par un p'-groupe alors on a aussi un isomorphisme naturel. Pour une action p-résoluble plus général, nous obtenons un résultat dans le cas des systèmes réalisables. Ces résultats nous conduisent à la conjecture qu’on a un isomorphisme naturel pour tout groupe fini p-local et toute action p-résoluble. Nous donnons quelque outils pour étudier cette conjecture. Nous travaillons sur les produits de groupes finis p-locaux avec la formule de Kunneth et les systèmes de liaison que se décomposent bien vis-à-vis de la suite exacte longue de Mayer-Vietoris. Finalement, nous étudions les sous-groupes essentiels d’un produit couronné par Cp. Nous finissons par des exemples qui soulignent, qu’en général, on ne peut espérer un isomorphisme entre H*(\ℒ\, M) et H*(Ƒᶜ, M)<br>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)
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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.
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The purpose of this study is to investigate the effects of a marbled coating applied on a triaxial woven structure. Although both of these techniques are traditionally used for many years, they are nowadays utilized in innovative ways, the marbling being applied on a large variety of surfaces such as wooden floors or ceramics and the triaxial weave being used as a hi-tech material for sports or in the automotive industry and having applications in diverse fields, from art to architecture. Their fusion, however, is a topic that has yet to be thoroughly explored, which makes for the motive of this thesis work, as an opening has been observed for the exploration of the expressive power of their combination. The experimental approach that has been taken towards this exploration will determine how the marbling effect may contribute to the visual expression of the structure. Multiple cycles of experiments have been conducted in an attempt to understand the behaviour of the chosen materials and their combination, the effect that various colour combinations have and the best possible pairings between the elements. The organic marbling combined with the geometric triaxial weave proved to generate the most powerful visual expression and the clearest result out of all the experiments. Thus five experimental textiles were developed in order to illustrate different aspects of this complex relationship, where the marbling would affect the visual expression of the structure by either enhancing or concealing the structural aspect and the contrast between the graphic element and the organic one would be a constant presence throughout the work. This work pushes the boundaries of conventional textile design and through the application of a textile thinking to unconventional materials a different type of expression is born. By mixing a limited amount of variables in multiple ways, a large range of visual effects may be achieved.
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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.
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En fabrication additive métallique par fusion laser sur lit de poudre, la géométrie et les caractéristiques mécaniques des pièces produites sont générées au cours de la fabrication. Ces deux aspects sont grandement influencés par les trajectoires du spot laser et par la maîtrise de l'énergie apportée à la poudre localement. La commande numérique dont le rôle est de générer les consignes à envoyer aux actionneurs a donc un impact conséquent sur la qualité des pièces produites.Ces travaux proposent d'étudier l'impact des traitements effectués dans la commande numérique sur les trajectoires réalisées et sur l'énergie apportée à la matière. Dans la littérature, peu de travaux traitent de ces aspects en fabrication additive. C'est pourquoi une plateforme expérimentale est mise en œuvre et utilisée afin d'analyser et de mieux comprendre les opérations actuellement implémentées dans les commandes numériques industrielles.Un modèle mathématique représentatif de la géométrie de la machine est d'abord établi. Ce modèle permet de convertir les trajectoires du spot laser en consigne pour les actionneurs. Le modèle développé est utilisé afin d'améliorer l'étape de calibration des machines. Une fois le système calibré, les consignes envoyées aux actionneurs sont étudiées. Les différents traitements effectués dans la commande numérique industrielle sont analysés, des limitations sont mises en évidence et plusieurs propositions d'améliorations sont implémentées. Tous ces développements sont ensuite utilisés afin de maîtriser finement l'énergie apportée à la matière dans le cas de certaines trajectoires adaptées au procédé. Les développements scientifiques proposés dans ces travaux sont tous validés expérimentalement sur une machine de fabrication additive ou sur le banc d'essai développé. Les travaux effectués permettent d'envisager de nombreuses perspectives concernant l'amélioration des traitements réalisés dans la commande numérique en fabrication additive<br>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
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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.
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Les formes asphériques et les surfaces complexes sont une classe très avancée d'éléments optiques. Leur application a considérablement augmenté au cours des dernières années dans les systèmes d'imagerie, l'astronomie, la lithographie, etc. La métrologie de ces pièces est très difficile, en raison de la grande gamme dynamique d'information acquise et la traçabilité à l'unité SI mètre. Elle devrait faire usage de la norme infinie; (Méthode de zone minimum ou la méthode Min-Max) pour calculer l'enveloppe entourant les points dans le jeu de données en réduisant au minimum la différence entre l'écart maximum et l'écart minimal entre la surface et l'ensemble de données. Cette méthode a une grande complexité en fonction du nombre de points, enplus, les algorithmes impliqués sont non-déterministes. Bien que cette méthode fonctionne pour des géométries simples (lignes, plans, cercles, cylindres, cônes et sphères), elle est encore un défi majeur lorsqu' utilisée pour des géométries complexes (asphérique et surfaces complexes). Par conséquent, l'objectif de la thèse est le développement des algorithmes d'ajustement Min-Max pour les deux surfaces asphériques et complexes, afin de fournir des algorithmes de référence robustes pour la grande communauté impliquée dans ce domaine. Les algorithmes de référence à développer devraient être évalués et validés sur plusieurs données de référence (Softgauges) qui seront générées par la suite<br>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
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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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Previous issue date: 2016-04-19<br>CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>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.<br>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.
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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.
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Previous issue date: 2003-12-16<br>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<br>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
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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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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia,
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2012_MiguelEduardoOrdonezMosquera.pdf: 8023732 bytes, checksum: 35d1c7594de0590e117992f16dcad7f5 (MD5)<br>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<br>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.
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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.
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Endometriosis is an oestrogen-dependent gynaecological condition defined as the presence of endometrial tissue outside the uterus cavity. The condition is predominantly found in women in their reproductive years, and associated with significant pelvic and abdominal chronic pain and infertility. The disease is believed to affect approximately 33% of women by a recent study. Currently, surgical intervention, often laparoscopic surgery, is the gold standard for diagnosing the disease and it remains an effective and common treatment method for all stages of endometriosis. Magnetic resonance imaging (MRI) of the patient is performed before surgery in order to locate any endometriosis lesions and to determine whether a multidisciplinary surgical team meeting is required. In this dissertation, our goal is to use image processing techniques to aid surgical planning. Specifically, we aim to improve quality of the existing images, and to automatically detect bladder endometriosis lesion in MR images as a form of bladder wall thickening. One of the main problems posed by abdominal MRI is the sparse anisotropic frequency sampling process. As a consequence, the resulting images consist of thick slices and have gaps between those slices. We have devised a method to fuse multi-view MRI consisting of axial/transverse, sagittal and coronal scans, in an attempt to restore an isotropic densely sampled frequency plane of the fused image. In addition, the proposed fusion method is steerable and is able to fuse component images in any orientation. To achieve this, we apply the Riesz transform for image decomposition and reconstruction in the frequency domain, and we propose an adaptive fusion rule to fuse multiple Riesz-components of images in different orientations. The adaptive fusion is parameterised and switches between combining frequency components via the mean and maximum rule, which is effectively a trade-off between smoothing the intrinsically noisy images while retaining the sharp delineation of features. We first validate the method using simulated images, and compare it with another fusion scheme using the discrete wavelet transform. The results show that the proposed method is better in both accuracy and computational time. Improvements of fused clinical images against unfused raw images are also illustrated. For the segmentation of the bladder wall, we investigate the level set approach. While the traditional gradient based feature detection is prone to intensity non-uniformity, we present a novel way to compute phase congruency as a reliable feature representation. In order to avoid the phase wrapping problem with inverse trigonometric functions, we devise a mathematically elegant and efficient way to combine multi-scale image features via geometric algebra. As opposed to the original phase congruency, the proposed method is more robust against noise and hence more suitable for clinical data. To address the practical issues in segmenting the bladder wall, we suggest two coupled level set frameworks to utilise information in two different MRI sequences of the same patients - the T2- and T1-weighted image. The results demonstrate a dramatic decrease in the number of failed segmentations done using a single kind of image. The resulting automated segmentations are finally validated by comparing to manual segmentations done in 2D.
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"The Fusion of Multimodal Brain Imaging Data from Geometry Perspectives." Doctoral diss., 2020. http://hdl.handle.net/2286/R.I.62817.
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abstract: The rapid development in acquiring multimodal neuroimaging data provides opportunities to systematically characterize human brain structures and functions. For example, in the brain magnetic resonance imaging (MRI), a typical non-invasive imaging technique, different acquisition sequences (modalities) lead to the different descriptions of brain functional activities, or anatomical biomarkers. Nowadays, in addition to the traditional voxel-level analysis of images, there is a trend to process and investigate the cross-modality relationship in a high dimensional level of images, e.g. surfaces and networks.
In this study, I aim to achieve multimodal brain image fusion by referring to some intrinsic properties of data, e.g. geometry of embedding structures where the commonly used image features reside. Since the image features investigated in this study share an identical embedding space, i.e. either defined on a brain surface or brain atlas, where a graph structure is easy to define, it is straightforward to consider the mathematically meaningful properties of the shared structures from the geometry perspective.
I first introduce the background of multimodal fusion of brain image data and insights of geometric properties playing a potential role to link different modalities. Then, several proposed computational frameworks either using the solid and efficient geometric algorithms or current geometric deep learning models are be fully discussed. I show how these designed frameworks deal with distinct geometric properties respectively, and their applications in the real healthcare scenarios, e.g. to enhanced detections of fetal brain diseases or abnormal brain development.<br>Dissertation/Thesis<br>Doctoral Dissertation Computer Science 2020
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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.
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"Binocular geometry and camera motion directly from normal flows." Thesis, 2009. http://library.cuhk.edu.hk/record=b6074789.
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Active vision systems are about mobile platform equipped with one or more than one cameras. They perceive what happens in their surroundings from the image streams the cameras grab. Such systems have a few fundamental tasks to tackle---they need to determine from time to time what their motion in space is, and should they have multiple cameras, they need to know how the cameras are relatively positioned so that visual information collected by the respective cameras can be related. In the simplest form, the tasks are about finding the motion of a camera, and finding the relative geometry of every two cameras, from the image streams the cameras collect.<br>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.<br>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.<br>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.<br>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.<br>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.<br>Yuan, Ding.<br>Adviser: Ronald Chung.<br>Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: .<br>Thesis submitted in: October 2008.<br>Thesis (Ph.D.)--Chinese University of Hong Kong, 2009.<br>Includes bibliographical references (leaves 121-131).<br>Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.<br>Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.<br>Abstracts in English and Chinese.<br>School code: 1307.
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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.
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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.
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碩士<br>長庚大學<br>醫療機電工程研究所<br>104<br>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.
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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.
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博士<br>國立交通大學<br>電控工程研究所<br>103<br>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.
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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.
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"Fusing scattered images with multiresolution point-based model." 2003. http://library.cuhk.edu.hk/record=b5891582.
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Lee Keung Tat.<br>Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.<br>Includes bibliographical references (leaves 81-86).<br>Abstracts in English and Chinese.<br>Abstract --- p.i<br>Acknowledgments --- p.iii<br>Chapter 1 --- Introduction --- p.1<br>Chapter 1.1 --- Motivation --- p.1<br>Chapter 1.2 --- Contribution --- p.3<br>Chapter 1.3 --- Previous Work --- p.5<br>Chapter 1.4 --- Thesis Organization --- p.9<br>Chapter 2 --- Overview --- p.10<br>Chapter 3 --- Data Acquisition --- p.14<br>Chapter 3.1 --- Acquiring the Surface Model --- p.14<br>Chapter 3.2 --- Camera Calibration --- p.16<br>Chapter 3.3 --- Capturing Image with Camera Pose --- p.18<br>Chapter 3.3.1 --- Fastrack --- p.19<br>Chapter 3.3.2 --- Tracking the Camera Pose --- p.21<br>Chapter 3.3.3 --- Calibrating the Tracking System --- p.23<br>Chapter 3.4 --- Summary --- p.32<br>Chapter 4 --- Data Fusion --- p.33<br>Chapter 4.1 --- Converting Surface Model to Point-Based Model --- p.33<br>Chapter 4.2 --- Registering the Radiance Values onto the Point-Based Model --- p.36<br>Chapter 4.3 --- Scattered Data Fitting --- p.40<br>Chapter 4.3.1 --- Spherical Delaunay Triangulation --- p.41<br>Chapter 4.3.2 --- Hierarchical Spherical Triangulation --- p.46<br>Chapter 4.3.3 --- Interpolation --- p.49<br>Chapter 4.4 --- Data Compression --- p.50<br>Chapter 4.5 --- Summary --- p.52<br>Chapter 5 --- Multiresolution Point-Based Representation and Rendering --- p.53<br>Chapter 5.1 --- Multiresolution Point-Based Representation --- p.55<br>Chapter 5.1.1 --- Construction --- p.57<br>Chapter 5.2 --- Rendering --- p.62<br>Chapter 5.2.1 --- Culling --- p.63<br>Chapter 5.2.2 --- Drawing the Node --- p.66<br>Chapter 5.3 --- Summary --- p.68<br>Chapter 6 --- Experimental Results --- p.69<br>Chapter 6.1 --- Tested Objects --- p.69<br>Chapter 6.2 --- Evaluation --- p.70<br>Chapter 6.3 --- Summary --- p.78<br>Chapter 7 --- Conclusion --- p.79<br>Chapter 7.1 --- Summary --- p.79<br>Chapter 7.2 --- Future Direction --- p.80<br>Bibliography --- p.81
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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.
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The aim of the thesis is to develop a method to identify driving lanes based on aerial images and existing spatial data. The proposed method uses up to date available data in which it identifies road surface marking (RSM). Polygons classified as RSM are further processed to obtain their vector line representation as the first partial result. While processing RSM vectors further, borders of driving lanes are modelled as the second partial result. Furthermore, attempts were done to be able to automatically distinguish between solid and broken lines for a higher amount of information contained in the resulting dataset. Proposed algorithms were tested in 20 case study areas and results are presented further in this thesis. The overall correctness as well as the positional accuracy proves effectivity of the method. However, several shortcomings were identified and are discussed as well as possible solutions for them are suggested. The text is accompanied by more than 70 figures to offer a clear perspective on the topic. The thesis is organised as follows: First, Introduction and Literature review are presented including the problem background, author's motivation, state of the art and contribution of the thesis. Secondly, technical and legal requirements of RSM are presented as well as theoretical concepts and...
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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.
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碩士<br>國立臺灣大學<br>土木工程學研究所<br>94<br>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.
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Cai, Chenghui. "Information-driven Sensor Path Planning and the Treasure Hunt Problem." Diss., 2008. http://hdl.handle.net/10161/626.
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