Дисертації з теми "Synthetic Geometries"
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Sciannandrone, Daniele. "Acceleration and higher order schemes of a characteristic solver for the solution of the neutron transport equation in 3D axial geometries." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112171/document.
Анотація:
Le sujet de ce travail de thèse est l’application de la méthode de caractéristiques longues (MOC) pour résoudre l’équation du transport des neutrons pour des géométries à trois dimensions extrudées. Les avantages du MOC sont sa précision et son adaptabilité, le point faible était la quantité de ressources de calcul requises. Ce problème est même plus important pour des géométries à trois dimensions ou le nombre d’inconnues du problème est de l’ordre de la centaine de millions pour des calculs d’assemblage.La première partie de la recherche a été dédiée au développement des techniques optimisées pour le traçage et la reconstruction à-la-volé des trajectoires. Ces méthodes profitent des régularités des géométries extrudées et ont permis une forte réduction de l’empreinte mémoire et une réduction des temps de calcul. La convergence du schéma itératif a été accélérée par un opérateur de transport dégradé (DPN) qui est utilisé pour initialiser les inconnues de l’algorithme itératif and pour la solution du problème synthétique au cours des itérations MOC. Les algorithmes pour la construction et la solution des opérateurs MOC et DPN ont été accélérés en utilisant des méthodes de parallélisation à mémoire partagée qui sont le plus adaptés pour des machines de bureau et pour des clusters de calcul. Une partie importante de cette recherche a été dédiée à l’implémentation des méthodes d’équilibrage la charge pour améliorer l’efficacité du parallélisme. La convergence des formules de quadrature pour des cas 3D extrudé a aussi été explorée. Certaines formules profitent de couts négligeables du traitement des directions azimutales et de la direction verticale pour accélérer l’algorithme. La validation de l’algorithme du MOC a été faite par des comparaisons avec une solution de référence calculée par un solveur Monte Carlo avec traitement continu de l’énergie. Pour cette comparaison on propose un couplage entre le MOC et la méthode des Sous-Groupes pour prendre en compte les effets des résonances des sections efficaces. Le calcul complet d’un assemblage de réacteur rapide avec interface fertile/fissile nécessite 2 heures d’exécution avec des erreurs de quelque pcm par rapport à la solution de référence.On propose aussi une approximation d’ordre supérieur du MOC basée sur une expansion axiale polynomiale du flux dans chaque maille. Cette méthode permet une réduction du nombre de mailles (et d’inconnues) tout en gardant la même précision.Toutes les méthodes développées dans ce travail de thèse ont été implémentées dans la version APOLLO3 du solveur de transport TDTThe topic of our research is the application of the Method of Long Characteristics (MOC) to solve the Neutron Transport Equation in three-dimensional axial geometries. The strength of the MOC is in its precision and versatility. As a drawback, it requires a large amount of computational resources. This problem is even more severe in three-dimensional geometries, for which unknowns reach the order of tens of billions for assembly-level calculations.The first part of the research has dealt with the development of optimized tracking and reconstruction techniques which take advantage of the regularities of three-dimensional axial geometries. These methods have allowed a strong reduction of the memory requirements and a reduction of the execution time of the MOC calculation.The convergence of the iterative scheme has been accelerated with a lower-order transport operator (DPN) which is used for the initialization of the solution and for solving the synthetic problem during MOC iterations.The algorithms for the construction and solution of the MOC and DPN operators have been accelerated by using shared-memory parallel paradigms which are more suitable for standard desktop working stations. An important part of this research has been devoted to the implementation of scheduling techniques to improve the parallel efficiency.The convergence of the angular quadrature formula for three-dimensional cases is also studied. Some of these formulas take advantage of the reduced computational costs of the treatment of planar directions and the vertical direction to speed up the algorithm.The verification of the MOC solver has been done by comparing results with continuous-in-energy Monte Carlo calculations. For this purpose a coupling of the 3D MOC solver with the Subgroup method is proposed to take into account the effects of cross sections resonances. The full calculation of a FBR assembly requires about 2 hours of execution time with differences of few PCM with respect to the reference results.We also propose a higher order scheme of the MOC solver based on an axial polynomial expansion of the unknown within each mesh. This method allows the reduction of the meshes (and unknowns) by keeping the same precision.All the methods developed in this thesis have been implemented in the APOLLO3 version of the neutron transport solver TDT
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Saccaro, Ludovica. "Vers l'évaluation du risque des anévrismes de l'aorte abdominale par modélisation géométrique et simulations hémodynamiques d'ordre réduit." Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0025.
Анотація:
Cette thèse se concentre sur une pathologie spécifique affectant la section abdominale de l'aorte, connue sous le nom d'anévrisme de l'aorte abdominale (AAA). Un anévrisme implique un affaiblissement persistant et localisé de la paroi du vaisseau, entraînant des élargissements et des renflements, provoquant une recirculation et une turbulence du flux sanguin.Notre thèse expose une méthodologie pour la modélisation géométrique des anévrismes abdominaux. Le processus comprend l'acquisition d'images de scanners CT, la reconstruction de la géométrie 3D de l'aorte et l'isolation de l'anévrisme. La phase de modélisation commence par l'identification et l'approximation de la ligne médiane du vaisseau aortique à l'aide de fonctions B-spline. La paroi aortique est ensuite partitionnée et profilée à l'aide de séries de Fourier.Pour évaluer son efficacité, la technique développée est appliquée à un ensemble de données de scanners CT de patients. Les reconstructions obtenues à partir des scans sont également présentées comme des exemples détaillant chaque étape de la procédure. De plus, une évaluation quantitative et la logique derrière les paramètres de modélisation sont expliquées. Ensuite, en tant que première application, la modélisation est intégrée à un processus de registration pour le diagnostic clinique et le suivi.La procédure de modélisation géométrique développée est utilisée dans un pipeline pour des simulations hémodynamiques et une évaluation des risques, en utilisant une approche de modélisation d'ordre réduit pour construire un espace de solution. Des simulations, utilisant des géométries paramétrées, sont réalisées dans des conditions réalistes, et des indicateurs de risque sont calculés et liés à la représentation géométrique à l'aide d'une fonction interpolante à base radiale. Enfin, des prédictions sur les indicateurs de risque sont obtenues pour une géométrie inconnue. Les résultats, bien que prometteurs, pourront être améliorés en augmentant de manière appropriée l'ensemble de données initial.Pour remédier à la pénurie mentionnée de données cliniques, nous avons élaboré un flux de travail automatisé pour générer des géométries synthétiques. Cette approche permet l'identification de paramètres géométriques pertinents et implique l'apprentissage automatique pour générer une population virtuelle de patients cohérente avec les données d'origine. En plus d'améliorer la capacité prédictive des modèles réduits, la méthode peut également être appliquée de manière prospective pour des essais in silico et des études impliquant des populations virtuelles de patientsThis thesis focuses on a specific pathology affecting the abdominal section of the aorta, known as abdominal aortic aneurysm (AAA). An aneurysm involves a persistent and localized weakening of the vessel wall, leading to enlargements and bulges, causing recirculation and turbulence of blood flow.Our thesis outlines a methodology for geometric modeling of abdominal aneurysms. The process involves acquiring CT images, reconstructing the aorta 3D geometry, and isolating the aneurysm. The modeling phase begins by identifying and approximating the centerline of the aortic vessel using B-spline functions. The aortic wall is then partitioned and profiled using Fourier series.To evaluate its effectiveness, the developed technique is applied to a dataset of CT scans from patients. Reconstructions obtained from the scans are also presented as examples to detail each step of the procedure. In addition, a quantitative evaluation and rationale behind modeling parameters are explained. Then, as a first application, the modeling is integrated into a registration process for clinical diagnosis and follow-up.The geometrical modeling procedure developed is used in a pipeline for hemodynamic simulations and risk assessment, employing a reduced-order modeling approach to construct a reduced solution space. Simulations, utilizing parameterized geometries, are conducted under realistic conditions, and risk indicators are computed and linked to the geometrical representation using Radial Basis Functions interpolant. Finally, predictions on risk indicators are obtained for an unknown geometry. The results, despite being promising, can be further improved by appropriately augmenting the initial dataset.To address the aforementioned scarcity of clinical data, we devised an automated workflow for generating synthetic geometries. This approach allows for the identification of relevant geometry parameters and involves machine learning to generate a virtual patient population consistent with the original data. In addition to improving the predictive capability of reduced models, the method can also be applied prospectively for in-silico trials and studies involving virtual patient populations
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Isgro, Francesco. "Geometric methods for video sequence analysis and applications." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/495.
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Coulter, Stewart. "Representation of geometric constraints in parametric synthesis." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/17982.
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Bresolin, Nadia Roberta Quaini. "GEOMETRIA SINTÉTICA: INVESTIGAÇÃO SOBRE O USO DE UM SOFTWARE DE GEOMETRIA DINÂMICA COMO MEIO PARA DEMONSTRAÇÕES VISUAIS." Centro Universitário Franciscano, 2016. http://www.tede.universidadefranciscana.edu.br:8080/handle/UFN-BDTD/594.
Анотація:
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This research aimed to investigate how the GeoGebra software can provide the development of creative, intuitive and visual abilities in the statement of theorems of synthetic geometry. The research was carried out with five students of the first year of high school in a state school of Rio Grande do Sul. This is a qualitative research carried out in the computer lab; data collection was obtained through the records of the constructions carried out by students and analyzed existing protocols in the software itself. The investigative activities, developed in workshop mode, consisted of four specific theorems of plane geometry, chosen at random and feasible to be offered to students of elementary school. The research results showed that the activities provided through the GeoGebra software, the development of creativity, the use of intuitive thinking and visualization as a way of analyzing the operation of ideas in the formulation of conjectures, which contributed to the construction of theorems, providing meaningful learning. Also, it indicates synthetic geometry as a way to perform logical statements of theorems, developing reasoning skills and justifications. In turn, the results showed that the use of GeoGebra software, used in construction, was key to achieving the goals in the research.
Este trabalho de pesquisa teve como objetivo investigar de que forma o software GeoGebra pode proporcionar o desenvolvimento de habilidades criativas, intuitivas e visuais na demonstração de teoremas de Geometria Sintética. A investigação foi realizada com cinco alunas do primeiro ano do Ensino Médio de uma Escola Estadual do Rio Grande do Sul. Trata-se de uma pesquisa de cunho qualitativo realizada em laboratório de informática; a coleta de dados foi obtida pelos registros das construções realizadas pelas estudantes e analisados os protocolos existentes no próprio software. As atividades investigativas, desenvolvidas na modalidade de oficina, consistiram de quatro teoremas específicos de Geometria Plana, escolhidos aleatoriamente e viáveis de serem propostos aos estudantes da escola básica. Os resultados da investigação demonstraram que as atividades propostas oportunizaram, por meio do software GeoGebra, o desenvolvimento da criatividade, o uso do pensamento intuitivo e a visualização como forma de analisar a exploração de ideias na formulação de conjecturas, o que contribuiu para a construção dos teoremas, propiciando uma aprendizagem significativa. Além disso, indica Geometria Sintética como uma forma de realizar demonstrações lógicas de teoremas, desenvolvendo habilidades de argumentação e justificativas. Por sua vez, os resultados mostraram que o uso do software GeoGebra, utilizado nas construções, foi fundamental para atingir os objetivos propostos na pesquisa.
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Duersch, Michael Israel. "Backprojection for Synthetic Aperture Radar." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4060.
Анотація:
Synthetic aperture radar (SAR) is a type of radar capable of high-resolution coherent imaging. In order to produce coherent imagery from raw SAR data, an image formation algorithm is employed. The various image formation algorithms have strengths and weaknesses. As this work shows, time-domain backprojection is one algorithm whose strengths are particularly well-suited to use at low-altitudes. This work presents novel research in three areas regarding time-domain backprojection. The first key contribution of this work is a detailed analysis of SAR time-domain backprojection. The work derives a general form of backprojection from first principles. It characterizes the sensitivities of backprojection to the various inputs as well as error sources and performance characteristics. This work then shows what situations are particularly well-suited to use of the backprojection algorithm, namely regimes with turbulent motion and wide variation in incidence angle across the range swath (e.g., low-altitude, airborne SAR).The second contribution of this work is an analysis of geometric signal correlation for multi-static, sometimes termed multiple-input and multiple-output (MIMO), imaging. Multi-static imaging involves forming multiple images using different combinations of transmitters and receivers. Geometric correlation is a measure of how alike observations of a target are from different aspect angles. This work provides a novel model for geometric correlation which may be used to determine the degree to which multi-static images are correlated. This in turn determines their applicable use: operating in the highly correlated regime is desirable for coherent processing whereas operating in a lower-correlation regime is desirable for obtaining independent looks. The final contribution of this work is a novel algorithm for interferometry based on backprojected data. Because of the way backprojected images are formed, they are less suited to traditional interferometric methods. This work derives backprojection interferometry and compares it to the traditional method of interferometry. The sensitivity and performance of backprojection interferometry are shown, as well as where backprojection interferometry offers superior results. This work finds that backprojection interferometry performs better with longer interferometric baseline lengths or systems with large measurement error in the baseline length or angle (e.g., low-altitude, airborne SAR).
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Morelli, Alessandra. "Synthesis of metal based interlocked architectures : spanning through oxidation states, geometries and coordination motifs." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/12685.
Анотація:
Efficient synthetic methods have been developed for catenates and rotaxanes based on tetrahedral and trigonal bipyrimidal metal complexes using the metal-bis-phenanthroline synthon pioneered in Strasbourg. The aim of this project was to investigate the possibility to synthesise mechanically interlocked architecture using metals with higher oxidation states, different geometries and higher coordination motifs. Chapter Two describes the synthesis of a general ligand system for rotaxane complexes of ions that prefer octahedral coordination – the commonest ligand geometry amongst transition metals but up to now a rare coordination mode for rotaxanes. Simple mixing of the components at room temperature is sufficient to assemble a broad range of octahedrally coordinated metal-[2]rotaxanes in excellent yields. The reactions have few, if any, by products and proceed under thermodynamic control in the absence of a catalyst or any other external reagents. Chapter Three reports the template-directed synthesis of a [2]catenate and a [2]rotaxane by a clipping approach around trivalent octahedral cobalt ions. Chapter Four reports the design and investigation of the synthesis of pentacoordinate rotaxane about divalent zinc and cadmium metals and of tetracoordinate rotaxane about divalent palladium. A clipping approach as well as a threading-and-capping approach were considered for both geometries, leading to interesting results involving the kinetics and thermodynamics of each complex. Zinc was suitable for the self-assembling of the macrocycle about the metal-thread complex but failed to hold the unstoppered thread in place to undergo capping reaction; cadmium on the contrary yielded rotaxane upon threading approach but lead to the formation of more thermodynamically stable hexacoordinate catenate upon ligand self-assembly via clipping approach. Palladium did not promote any self-organization towards the assembly of the macrocycle via clipping approach about the preformed thread.
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Ciobotarescu, Simona. "Synthesis, molecular modeling and photochromic behaviour of polysiloxanes containing azo-groups with different geometries." Thesis, Angers, 2020. http://bu.univ-angers.fr/Contact.
Анотація:
La présente thèse représente une étude complexe des azopolysiloxanes photosensibles et rejoint les techniques théoriques et expérimentales. Le thème tourne autour du phénomène de transport de masse des azopolymères induit par la photoisomérisation des azobenzènes. La conversion transt – cis de l'azobenzène et de ses dérivés est un processus réversible actionné par la lumière, qui permet le réarrangement de la matière environnante au niveau nano et micro. Cette propriété est exploitée pour fabriquer des réseaux de relief de surface (SRG) avec caractéristiques géométriques specifiques. Les présentes études visent à comprendre ce mécanisme complexe, sujet à une grande controverse parmi les différents groupes de recherche. Les paramètres qui contrôlent le processus sont traités et analysés. L'étude expérimentale comprend la synthèse et la caractérisation de quatre azopolysiloxanes qui sont ensuite analysés pour leur capacité d'obtenir des SRG. Le comportement photochromique est évalué par des expériments d'irradiation à différentes intensités lumineuses, en présence ou l'absence d'une lumière d'assistance qui devrait intensifier l'isomérisation. La simulation informatique se concentre sur la diffusion des molécules dans le système: une molécule de type azobenzène (moteur moléculaire) diluée dans le milieu hôte. Des calculs de modélisation moléculaire sont effectués pour des moteurs de différentes longueurs et avec différents temps d'isomérisation (isomérisation rapide ou lente) afin de définir la relation entre ces paramètres et la diffusion. Fournir des informations expérimentales et théoriques sur les azopolymères, est trop important pour comprendre la formation de SRGThe herein thesis represents a complex study of photosensitive azopolysiloxanes and rejoins both theoretical and experimental techniques. The theme revolves around the azopolymer’s mass transport phenomenon induced by the photoisomerization of azobenzenes. Trans- to cis conversion of azobenzene and its derivatives is a reversible light actuated process that enables the rearrangement of surrounding matter at nano and micro level. This property is exploited to fabricate surface relief gratings (SRG) with certain geometrical features. The present studies are directed to comprehension of this complex mechanism, subject to great controversial among different research groups. The parameters that control the process are addressed and analyzed. Experimental study comprises the synthesis and characterization of four azopolysiloxanes which are then analyzed for the capacity to obtain SRG. Photochromic behaviour is evaluated through irradiation experiments at different light intensity, in the presence or absence of an assistance light that supposedly intensifies isomerization. Computer simulation focuses on diffusion of the molecules in the system: one azobenzene – like molecule (molecular motor) diluted in the host medium. Molecular modeling calculations are performed for motors with different lengths and with various isomerization times (fast or slow isomerization) in order to define the relation between these parameters and diffusion. Providing experimental and theoretical info on azopolymers is part of the SRG formation insight
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Oliveira, Júnior José William de. "Três pontos de vista sobre cônicas." Mestrado Profissional em Matemática, 2018. http://ri.ufs.br/jspui/handle/riufs/9321.
Анотація:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESIn the present work, we tried to investigate the conics in the synthetic, analytical and projective contexts, as well as to know some applications and properties of these curves. In the synthetic approach, it was emphasized a lithe of the historical aspects, the works made by Apollonius and Dandelin, a characterization for tangent and normal lines and re ecting properties. In the analytical approach, the Cartesian, polar and parametric equations were described, as well as the applications in the Kepler Laws. In the projective approach, the concepts of projective plane, projective point, projective line and projective applications were used to give meaning to the conic in the projective universe, in addition the Theorews of Pascal and Brianchon were demonstrated.
No presente trabalho, procurou-se investigar as cônicas nos contextos sintético, analítico e projetivo, bem como conhecer algumas aplicações e propriedades dessas curvas. Na abordagem sintética, foram enfatizados um pouco do aspecto histórico, os trabalhos feitos por Apolônio e Dandelin, uma caracterização para retas tangentes e normais e as propriedades refletoras. Na abordagem analítica, foram descritas as equações cartesianas, polares e paramétricas, como também as aplicações nas Leis de Kepler. Na abordagem projetiva, foram trabalhados os conceitos de plano projetivo, ponto projetivo, reta projetiva e aplicações projetivas para dar significado as cônicas no universo projetivo, além disso foram demonstrados os teoremas de Pascal e Brianchon.
São Cristóvão, SE
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Mukesh, Jain Prakhyaa. "A Synthesis of Geometry and Light." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/101967.
Анотація:
The poetics of an architecture of a moment is explored through design of a contemplative room (wherin the geometric transformation of a cubic base to a cone) demonstrates the rhythmn and proportion of the construction of the room and the relative motion of the sun in the space. The relationship of the sun rays on the walls of the room passing through a reflecting pool are shown using demonstrative and constructive means of descriptive geometry as both the design generator and poetic expression.The composition of the buildings reveals the play of light on form.Master of Architecture
An exploration to understand the relationship of architecture and the material sensible world. The work seeks to reveal that through the tangible architectural strategies of form, structure, material and light, the intangible qualities of architecture are defined.
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Lal, Mithun. "Synthetic environment for machine learning experiments." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/236035/2/Mithun%2BLal%2BThesis%282%29.pdf.
Анотація:
This thesis addresses the problem of data scarcity in human deep-learning applications. Automated estimation of human shape and pose from an image is challenging. It is even more difficult to map the identified human pixels onto a 3D model. Existing deep-learning models learn to map manually labelled human pixels in 2D images onto human surface, which is prone to human error, and the sparsity of annotated data leads to sub-optimal results. We solve this problem by generating realistic artificial human video data to train 2D-3D human mapping models and show promising results when compared to models trained on real data.
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Mercier, Patrick H. J. "Crystal chemistry of natural and synthetic trioctahedral micas: Exploring the limits of geometric crystal chemical models." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/29032.
Анотація:
Seventy-five synthetic powder trioctahedral mica samples (between Mg, Co, Ni, and Fe end members, with different degrees of oxidation, vacancy and Al/Si contents, and including an OH/F substitution series) were studied by room-temperature powder X-ray diffraction. The iron-bearing samples were studied by 57Fe Mossbauer spectroscopy. Subsets of the samples were also characterized by scanning electron microscopy combined with energy dispersive spectroscopy, optical microscopy, X-ray fluorescence spectroscopy, and gas chromatography. Lattice parameters (refined under the 1M stacking polytype, space group C2/m) were determined for all powder samples and iron site populations ([4]Fe 3+, [6]Fe2+, and [6]Fe 2+) were obtained from Mossbauer spectroscopy.
The relation (c/a)cosbeta* = 113 was found to hold exactly (within experimental error) for all synthetic powders whereas it does not hold in general for synthetic and natural 1M single-crystals. The above relation is predicted to hold for geometric home-octahedral sheets (having equal M1 and M2 site bond lengths) and not to hold for geometric meso-octahedral sheets (having unequal M1 and M2 site bond lengths). The counter-rotation of the M2 site of 1M single-crystals exactly (within experimental error) follows the geometric meso-octahedral sheet model, which, assuming a uniform octahedral sheet height and site-specific M1 and M2 bond lengths, predicts site-specific flattening angles and a counter-rotation angle for the M2 site which is uniquely determined by the bond length difference between the M1 and M2 sites. A geometric meso-octahedral 2:1 layer silicate was shown to require corrugated tetrahedral sheets composed of bond-distorted tetrahedra. Key geometric meso-octahedral distortions in 1M single-crystals were identified and elucidated: (i) intra-layer top-bottom displacements within a TOT layer; and (ii) a tetrahedral bending angle between the apical bond and the pyramidal base formed by the three basal bonds. Plots of lattice parameter b versus average-octahedral-bond-length allowed the following distinction to be made: Unoxidized divalent synthetic solid solution series tend to evolve along constant flattening-angle lines whereas trivalent octahedral cation and vacancy bearing natural single-crystals and synthetic powders follow trends with varying flattening angles. We found that the bond length of a given interlayer cationic species monotonously increases as the tetrahedral rotation angle alpha decreases in trioctahedral-1 M single-crystals. An upper limit of tetrahedral rotation of alpha = 9.5° was demonstrated to occur in trioctahedral-1M K-rich micas having an <AlSi3> sheet, for both synthetic powders and natural single-crystals.
Other attempts at applying geometric crystal chemical models and at identifying structure-chemical relationships from structural refinement data will benefit from the perspective of our more complete and systematic approach based on pursuing simple geometrical models using 'regular' coordination polyhedrons and characteristic cation-specific bond lengths up to the limit beyond which such models are shown to necessarily breakdown because of unavoidable 'non-regular' polyhedral distortions. (Abstract shortened by UMI.)
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Allison, Morgan Charles. "Chemistry of Layered AB3Si2Sn7O16 Stannides." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/20154.
Анотація:
The AB3Si2Sn7O16 phases (sg: P3 ̅m1) are a series of layered semiconductor oxides built from sheets of oxygen-linked A(SnO)6 octahedra and 3d transition metal rich tin-centred kagomé lattices separated by SiO4 tetrahedra. Oxide materials possessing novel geometrically frustrated architectures such as the triangular arrangement of ising spins in the kagomé lattice has garnered considerable recent interest from the materials science field due to the observation of quantum spin liquid states. These states are of interest to scientists, as they will help to connect the gap in understanding between the electronic ground states of matter and crystal structure. In a more practical sense, they are also interesting as they are among the most promising candidates for the building blocks of quantum computers. The novel architecture of SiO4-separated tin and transition metal rich layers in the AB3Si2Sn7O16 structure promises to allow for the synthesis of a significant number of chemically tuneable geometrically-frustrated oxides, however, only limited information on the crystal chemistry of this structure type exists which in turn hinders practical investigation of the links between structure and material properties. This investigation helps to bridge this gap by detailing the changes in chemical and magnetic behaviour as different sites in the tin-oxide framework are systematically substituted by different third, fourth and fifth row elements. Determination of the changes in the final structures and elemental composition will be determined using a combination of powder diffraction measurements and magnetic probes.
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Chen, Kuan-Hao. "Creating Extended Landau Levels of Large Degeneracy with Photons." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1542878428843845.
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Meng, Jian. "A geometric theory for synthesis, analysis and design of sub-6 DoF parallel manipulators /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?ECED%202007%20MENGJ.
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Zebin, Su. "DESIGN, SYNTHESIS, AND SELF-ASSEMBLY OF GIANT SHAPE AMPHIPHILES WITH PRECISELY CONTROLLED COMPOSITIONS, INTERACTIONS, AND GEOMETRIES VIA A MOLECULAR LEGO APPROACH." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1572887748730283.
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ANDRUSKI, STEPHEN WALTER. "I. GEOMETRIC EFFECTS IN SULFUR LONE-PAIR INTERACTIONS. II. SYNTHETIC USES OF SULFOXIMINES, SULFOXIDES AND HEMITHIOKETALS WITH STEREOCHEMICAL CONTROL." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184042.
Анотація:
An X-ray crystal analysis of l,8-Bis(methylthio)naphthalene (1.1) revealed that the molecule has a geometry in which the naphthalene ring is twisted to place the 1,8- substituents symmetrically above and below the naphthalene plane. The methyl groups are rotated out of the naphthalene plane. X-ray crystal analysis of Naphtho [1, 8-b, c] -1, 5- dithiocin (1.2) showed that naphthalene ring is twisted as in 1.1, however the disposition of the sulfurs above and below the plane is unsymmetrical. The aliphatic portion of the molecule is in a chair-like conformation. Comparison of these two structures indicates that the bond asymmetry across the naphthalene ring is due largely to bond stretching to relieve steric overcrowding. MNDO calculations on 1.1 and 1.2 give HOMO's which are predominantly naphthalene in character. Our MNDO eigenvalues for 1.1 and naphtho[l,8-d,e]-l,3-dithiin (2.1) correlate well with their PES ionization potentials. We predict an ionization potential of -7.60-7.76eV for 1.2. Reduction of the ethylene hemithioketal of norcamphor is shown to proceed with heterolysis of the carbon-oxygen bond and hydride attack on the resulting thionium ion occurring from the sterically less hindered exo face of the norbornane moiety. The stereochemistry of the resulting substituted norbornanes (3.4 and 3.5) is proved to be endo. In the reduction of N-phthalimido sulfoximines to sulfoxides with hydrazine in ethanol, a species is formed which gives reduction of certain unsaturated compounds. The reducing species is shown not to be diimide. Formation of 1,1-diazene is a possible explanation for the experimental results. The cycloaddition of (±)-S-2'-thienyl-S-vinyl-Nphthalimidosulfoximine ((±)-5.1g) with cyclopentadiene proceeds in good yield, however asymmetric induction in the resulting adducts is negligible. This strongly indicates that steric factors are controlling the asymmetric induction in this cycloaddition. (±)-Thiochromone-l-oxide (±)-5.8) and (±)-N-phthalimido-l-imino-4-thiochromone-l-oxide (±)- 5.6) are shown to undergo Diels-Alder reactions with cyclopentadiene in good yields giving only endo products with good diastereoselectivity. The diastereoselectivity of the reaction of (±)-5.8 with cyclopentadiene is shown to increase when the reaction is run at -78° with AlCl₃ as a catalyst. These results can be interpreted on the basis of approach of the diene on the less hindered face of the more reactive conformer.
18
Robbeloth, Michael Christopher. "Recognition of Incomplete Objects based on Synthesis of Views Using a Geometric Based Local-Global Graphs." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1557509373174391.
19
Shiping, Liu. "Synthetic notions of curvature and applications in graph theory." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-102197.
Анотація:
The interaction between the study of geometric and analytic aspects of Riemannian manifolds and that of graphs is a very amazing subject. The study of synthetic curvature notions on graphs adds new contributions to this topic. In this thesis, we mainly study two kinds of synthetic curvature notions: the Ollivier-Ricci cuvature on locally finite graphs and the combinatorial curvature on infinite semiplanar graphs.
In the first part, we study the Ollivier-Ricci curvature. As known in Riemannian geometry, a lower Ricci curvature bound prevents geodesics from diverging too fast on average. We translate this Riemannian idea into a combinatorial setting using the Olliver-Ricci curvature notion. Note that on a graph, the analogue of geodesics starting in different directions, but eventually approaching each other again, would be a triangle. We derive lower and upper Ollivier-Ricci curvature bounds on graphs in terms of number of triangles, which is sharp for instance for complete graphs. We then describe the relation between Ollivier-Ricci curvature and the local clustering coefficient, which is an important concept in network analysis introduced by Watts-Strogatz.
Furthermore, positive lower boundedness of Ollivier-Ricci curvature for neighboring vertices imply the existence of at least one triangle. It turns out that the existence of triangles can also improve Lin-Yau\'s curvature dimension inequality on graphs and then produce an implication from Ollivier-Ricci curvature lower boundedness to the curvature dimension inequality.
The existence of triangles prevents a graph from being bipartite. A finite graph is bipartite if and only if its largest eigenvalue equals 2. Therefore it is natural that Ollivier-Ricci curvature is closely related to the largest eigenvalue estimates. We combine Ollivier-Ricci curvature notion with the neighborhood graph method developed by Bauer-Jost to study the spectrum estimates of a finite graph. We can always obtain nontrivial estimates on a non-bipartite graph even if its curvature is nonpositive. This answers one of Ollivier\'s open problem in the finite graph setting.
In the second part of this thesis, we study systematically infinite semiplanar graphs with nonnegative combinatorial curvature. Unlike the previous Gauss-Bonnet formula approach, we explore an Alexandrov approach based on the observation that the nonnegative combinatorial curvature on a semiplanar graph is equivalent to nonnegative Alexandrov curvature on the surface obtained by replacing each face by a regular polygon of side length one with the same facial degree and gluing the polygons along common edges.
Applying Cheeger-Gromoll splitting theorem on the surface, we give a metric classification of infinite semiplanar graphs with nonnegative curvature. We also construct the graphs embedded into the projective plane minus one point. Those constructions answer a question proposed by Chen.
We further prove the volume doubling property and Poincare inequality which make the running of Nash-Moser iteration possible. We in particular explore the volume growth behavior on Archimedean tilings on a plane and prove that they satisfy a weak version of relative volume comparison with constant 1.
With the above two basic inequalities in hand, we study the geometric function theory of infinite semiplanar graphs with nonnegative curvature. We obtain the Liouville type theorem for positive harmonic functions, the parabolicity. We also prove a dimension estimate for polynomial growth harmonic functions, which is an extension of the solution of Colding-Minicozzi of a conjecture of Yau in Riemannian geometry.
20
Beck, Joseph A. "Stochastic Mistuning Simulation of Integrally Bladed Rotors using Nominal and Non-Nominal Component Mode Synthesis Methods." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1278600105.
21
Posser, Gracieli. "Dimensionamento de portas lógicas usando programação geométrica." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/29571.
Анотація:
Neste trabalho é desenvolvida uma ferramenta de dimensionamento de portas lógicas para circuitos integrados, utilizando técnicas de otimização de problemas baseadas em Programação Geométrica (PG). Para dimensionar as portas lógicas de um circuito, primeiramente elas são modeladas usando o modelo de chaves RC e o atraso é calculado usando o modelo de Elmore, que produz funções posinomiais possibilitando a resolução do problema por programação geométrica. Para cada porta é utilizado um fator de escala que multiplica a largura dos seus transistores, onde as variáveis que representam os fatores de escala são as variáveis de otimização do problema. O dimensionador de portas desenvolvido neste trabalho é para circuitos CMOS e é parametrizável para diversas tecnologias de fabricação CMOS. Além disso, a otimização pode ser feita de duas maneiras, minimizando o atraso restringindo a área do circuito ou, minimizando a área e restringindo o atraso do circuito. Para testar o dimensionador de portas foram consideradas duas tecnologias de fabricação diferentes, 45nm e 350nm, onde os resultados foram comparados com o dimensionamento fornecido em uma típica biblioteca de células. Para a tecnologia de 45nm, o dimensionamento de portas minimizando o atraso, fornecido pelo método proposto neste trabalho, obteve uma redução, em média, de 21% no atraso, mantendo a mesma área e potência do dimensionamento fornecido pela biblioteca de standard cells. Após, fez-se uma otimização de área, ainda considerando a tecnologia de 45nm, onde o atraso é restrito ao valor encontrado na minimização de atraso. Essa otimização secundária resultou em uma redução média de 28,2% em área e 27,3% em potência, comparado aos valores dados pela minimização de atraso. Isso mostra que, ao fazer a minimização de atraso seguida da minimização de área, ou vice-versa, encontra-se o menor atraso e a menor área para o circuito, onde uma otimização não impede a outra. As mesmas otimizações foram feitas para a tecnologia de 350nm, onde o dimensionamento de portas considerando a minimização de atraso obteve uma redução, em média, de 4,5% no atraso, mantendo os valores de consumo de potência e área semelhantes aos valores dados pelo dimensionamento fornecido em uma biblioteca comercial de células em 350nm. A minimização de área, feita em seguida, restringindo o atraso ao valor dado pela minimização de atraso foi capaz de reduzir a área em 29,9%, em média, e a potência em 28,5%, em média.In this work a gate sizing tool is developed using problem optimization techniques based on Geometric Programming. To size the gates in a circuit, first, the logic gates are modeled using the RC switch model and the delay is calculated using Elmore delay model, which produces posynomial functions, enabling the problem solution by geometric programming. For each port a scale factor is set that multiplies the transistors width, where the variables that represent the scale factors are the problem optimization variables. Gate sizing developed in this work is for CMOS circuits and is configurable to several CMOS manufacturing technologies. Moreover, the optimization can be done in two ways, minimizing delay restricting area or by minimizing area restricting circuit delay. In this work, gate sizing tests were made considers two different technologies, 45nm and 350nm, where the results were compared with the sizing available in a typical standard-cell library. For 45nm technology, the gate sizing proposed in this work considering delay minimization, obtained a reduction, in average, of 21% in delay, keeping the same area and power values of the sizing provided by standard-cells library. After, it was made an area optimization restricting delay to the value found at delay minimization. This optimization allowed an average reduction of 28.2% in area and 27.3% in power consumption, compared to the values obtained by delay minimization. This shows that by making the minimization of delay followed by the minimization of area, the smallest delay and the smallest area for the circuit is found, where an optimization does not prevent the other. The same optimizations were made for 350nm technology, where gate sizing considering delay minimization achieved a reduction, on average, of 4.5% in delay, keeping power consumption and area values similar to the values given using the sizes found in a commercial standard-cell library in 350nm. The area minimization, restricting delay to the value given by delay minimization, was able to reduce the area in 29.9% and power at 28.5%, on average.
22
Tong, Yuxuan. "Four-bar Linkage Synthesis for a Combination of Motion and Path-point Generation." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1366643444.
23
Wang, Hongqing Vincent. "A Unit Cell Approach for Lightweight Structure and Compliant Mechanism." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7561.
Анотація:
Cellular structures are present from the atomic level all the way up to patterns found in human skeleton. They are prevailing structures in the nature and known for their excellent mechanical, thermal, and acoustic properties. Two typical types of cellular structures, lightweight structures and compliant mechanisms, are investigated. Lightweight structures are rigid and designed to reduce weight, while increasing strength and stiffness. Compliant mechanisms are designed to transform motions and forces. Most available artificial lightweight structures are patterns of primitives. However, the performance of lightweight structures can be enhanced by using adaptive cellular structures with conformal strut orientations and sizes, like the trabeculae in femoral bone. Bending, torsion, and nonlinear behaviors of compliant mechanisms have not been sufficiently studied.
In order to design adaptive cellular structures, a new unit cell, the unit truss is proposed. The unit truss approach facilitates the design of adaptive cellular structures for enhanced mechanical properties via geometric modeling, finite element analysis, shape optimization, and additive fabrication. Four research questions, which address representation, structural analysis, design synthesis, and manufacturing respectively, are raised and answered. Unit truss enables representation and mechanics analysis for adaptive cellular structures. A synthesis method using engineering optimization algorithms is developed to systematically design adaptive cellular structure. Two examples, graded cellular structure for prosthesis and compliant mechanism for morphing wings, are studied to test the unit truss approach.
24
Aimedee, Marie Fidèle. "Synthesis and Control of Reconfigurable mechanisms." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22641/document.
Анотація:
Cette thèse aborde principalement trois grands aspects tels que la systématisation et l'analyse structurale, la modélisation géométrique et cinématique et les stratégies de contrôle. La première partie de la thèse est consacrée à l'élaboration d'une approche pour la systématisation des mécanismes reconfigurables selon leurs paramètres structuraux tels que la mobilité, la connectivité, la redondance et l’hyperstatisme. Ces paramètres nous permettent de comprendre les mécanismes et de les systématiser selon leur type de mouvement ; le mécanisme peut être isostatique ou hyperstatique, redondant ou non-redondant, avec ou sans mobilités internes, etc. Afin de résoudre les problèmes pratiques de modélisation, contrôle, simulation et développement du robot, les paramètres structuraux sont nécessaires. Différents types de singularités sont systématisés et analysés en tenant compte de paramètres structuraux. En plus, pour connaître les positions et les orientations relatives des membres du robot, nous avons besoin de calculer le modèle géométrique. Nous utilisons la méthode du Système de Coordonnées Voyageur pour déterminer la position et l'orientation des membres à chaque instant. Pour connaître les vitesses linéaires et angulaires des membres, nous devons formuler les équations cinématiques pour le robot étudié. La partie contrôle est dédiée à l'élaboration de stratégies de génération de trajectoire et de contrôle, sur la base de la redondance d’actionnement. La difficulté dans la commande est de développer une loi de contrôle avancée pour la synchronisation de plusieurs actionneurs afin d'avoir une transition fluide d'un mode d'assemblage à un autre, ceci sans endommager le robot. Le choix des liaisons actionnées joue également un rôle essentiel en garantissant une haute performance et la contrôlabilité du mécanisme au passage par les configurations singulières. Dans cette thèse, nous nous concentrons sur le mécanisme à une seule boucle fermée de type 8-bar afin d’illustrer les développements réalisés dans les trois parties mentionnées ci-dessus. Il a été démontré que ce mécanisme présente une capacité intéressante de reconfiguration. Il dispose de deux degrés de mobilité dans une configuration générale, mais a besoin d'au moins cinq moteurs pour être entièrement contrôlés dans toutes les configurations singulièresThis thesis mainly addresses three major aspects such as systematization and structural analysis, geometric and kinematic formulation and control strategies. The first part of the thesis is dedicated to the development of a systematization approach for reconfigurable mechanisms with respect to their structural parameters such as mobility, connectivity, redundancy and number of overconstraints. These parameters help us to understand the mechanism and to systematize it according to type of motion, whether the mechanism is overconstrained or non-overconstraint, redundant or non-redundant, with/without internal mobilites, etc. To resolve the practical problems of modeling, control, simulation and development of the robot, the structural parameters are required. Various types of singularities are also systematized and analyzed by taking into account the structural parameters. Further to know the relative location of robot links, we need to compute the geometric model. We use Travel Coordinate System method to determine the position and orientation of links at each instant. To find out the linear and angular velocities of links, we need to formulate the kinematic equations for the robot under consideration. The control part is dedicated to the development of trajectory generation and control strategies, based on actuation redundancy. The challenging task is to develop an advanced control law in order to synchronize several actuators to have a smooth transition from one assembly mode to another without causing wear and tear to the robot. Choice of actuated joints also plays a vital role in ensuring high performance and controllability of the mechanism when crossing singular configurations. In this thesis we focus on the 8-bar single loop mechanism to illustrate the developments achieved in the three parts mentioned above. It has been shown that, this mechanism exhibits an interesting capacity to reconfigure. It has two degrees of mobility in a general configuration but needs at least five motors to be fully controlled in all singular configurations
25
Bár, Filip. "Infinitesimal models of algebraic theories." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267026.
Анотація:
Smooth manifolds have been always understood intuitively as spaces that are infinitesimally linear at each point, and thus infinitesimally affine when forgetting about the base point. The aim of this thesis is to develop a general theory of infinitesimal models of algebraic theories that provides us with a formalisation of these notions, and which is in accordance with the intuition when applied in the context of Synthetic Differential Geometry. This allows us to study well-known geometric structures and concepts from the viewpoint of infinitesimal geometric algebra. Infinitesimal models of algebraic theories generalise the notion of a model by allowing the operations of the theory to be interpreted as partial operations rather than total operations. The structures specifying the domains of definition are the infinitesimal structures. We study and compare two definitions of infinitesimal models: actions of a clone on infinitesimal structures and models of the infinitesimalisation of an algebraic theory in cartesian logic. The last construction can be extended to first-order theories, which allows us to define infinitesimally euclidean and projective spaces, in principle. As regards the category of infinitesimal models of an algebraic theory in a Grothendieck topos we prove that it is regular and locally presentable. Taking a Grothendieck topos as a base we study lifts of colimits along the forgetful functor with a focus on the properties of the category of infinitesimally affine spaces. We conclude with applications to Synthetic Differential Geometry. Firstly, with the help of syntactic categories we show that the formal dual of every smooth ring is an infinitesimally affine space with respect to an infinitesimal structure based on nil-square infinitesimals. This gives us a good supply of infinitesimally affine spaces in every well-adapted model of Synthetic Differential Geometry. In particular, it shows that every smooth manifold is infinitesimally affine and that every smooth map preserves this structure. In the second application we develop some basic theory of smooth loci and formal manifolds in naive Synthetic Differential Geometry using infinitesimal geometric algebra.
26
Lehnen, Matheus Vicenzo. "Caracterização fluidodinâmica e térmica de jatos sintéticos." Universidade do Vale do Rio dos Sinos, 2012. http://www.repositorio.jesuita.org.br/handle/UNISINOS/4318.
Анотація:
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Matheus Vicenzo Lehnen.pdf: 7507080 bytes, checksum: 1036a30adcb3840ea0e5fcb545f29987 (MD5)Made available in DSpace on 2015-07-08T14:34:31Z (GMT). No. of bitstreams: 1 Matheus Vicenzo Lehnen.pdf: 7507080 bytes, checksum: 1036a30adcb3840ea0e5fcb545f29987 (MD5) Previous issue date: 2012-05
Milton Valente
Nos dias atuais, os componentes eletrônicos estão cada vez mais potentes e com mais dispositivos integrados e há a necessidade de uma dissipação térmica mais eficiente. Os atuais ventiladores e dissipadores de calor usando ar como fluido de trabalho estão ficando obsoletos. Por este motivo, torna-se necessário o desenvolvimento de um sistema mais eficiente. Existem três técnicas principais em estudo nesta área: resfriamento líquido, trocadores de calor compostos por microcanais e jatos sintéticos como transmissores de quantidade de movimento ao fluido. Entretanto, a análise em pequena escala encontra limitações experimentais de modo que uma abordagem por Dinamica de Fluidos Computacional (Computational Fluid Dynamics – CFD) é mais recomendável para caracterizar e validar o desempenho dos jatos sintéticos. O objetivo principal deste trabalho é realizar uma análise fluidodinâmica de jatos sintéticos e caracterizar a troca térmica de jatos sintéticos colidindo sobre uma superfície aquecida, através de simulação numérica. A flexibilidade da aproximação numérica também possibilita o estudo da sensibilidade do design a vários parâmetros físicos e geométricos, tais como o número de Reynolds, a frequência do atuador, o número de Prandtl, a distância da placa aquecida ao orifício da cavidade, o formato do orifício do atuador, a profundidade da cavidade e a espessura da placa do orifício. Os resultados caracterizam o efeito dos parâmetros físicos e geométricos de interesse na formação do jato e na dissipação térmica. O conhecimento agregado neste estudo permitiu determinar uma correlação para o número de Nusselt em função da frequência adimensional – o número de Strouhal – do número de Reynolds, do número de Prandtl e da distância adimensional da superfície aquecida ao orifício. Assim, é possível prever o comportamento de tais jatos sobre a superfície aquecida, e assim contribuir para os atuais estudos nesta linha de pesquisa. Os resultados apresentados tem então aplicação em estudos posteriores, de maior complexidade de design com atuadores combinados com trocadores de calor de aletas, coolers e micro canais, resultando em avanços na área de resfriamento de microchips.
Current electronic components are becoming ever more potent and densly integrated, which requires further increases in the efficiency of heat dissipation. With current fan-based heat dissipation techniques with air as the working fluid becoming outdated, there is a pressing need to develop more eficient methods to cope with demand. So far, three techniques have been the primary focus of studies in this area: liquid cooling, microchannel heat exchangers and synthetic jets used to promote increased momentum transfer. Analysis of such devices at the small physical scale of electronic components is somewhat problematic in experimental form so that a computational fluid dynamics (CFD) approach is recommended. The main objective of this study is thus to utilize a CFD approach to establish the performance characteristics of a synthetic jet impacting against a heated surface. The flexibility of a numerical approach also allows the examination of the sensibility of the design with respect to several physycal and geometric parameters such as Reynolds number, pulsing frequency, jet orifice shape and size, cavity size and distance between the heated surface and the device. Such results, provide insight in the effect of physical and geometric parameters in the jet formation and heat dissipation. The combined knowledge of this study allowed the development of a practical correlation for the Nusselt number based on the Strouhal number (normalized pulsing frequency), Reynolds number, Prandtl number and the distance between the heated surface and the synthetic jet. This result allows improved predictions of a jet impacting against a heated surface and, consequently, adds an important contribution to other studies in this area. It is expected that the results presented here will be the starting point for further work, in which increasingly complex geometries such as actuators combined with heat exchangers equipped with fins, coolers or microchannels are examined to further improve the knowledge in the field of electronic cooling.
27
Van, Meter David S. III. "Synthesis and Characterization of Surface-Confined Ionic Liquid Stationary Phases for High Performance Liquid Chromatography." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1227275073.
28
Beck, Joseph A. "Fundamental Understanding of Blisk Analytical Response." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1367848915.
29
Antoine, Mathieu. "Les techniques algorithmiques du codage Octree appliquées à l'analyse de volumes tridimensionnels de données numériques." Grenoble 1, 1988. http://www.theses.fr/1988GRE10042.
Анотація:
Les principales techniques d'exploitation des donnees numeriques sur ordinateur sont introduites. Une methodologie d'analyse par synthese d'image et ses differentes mises en oeuvre algorithmiques sont decrites. Dans une deuxieme partie, il est presente l'etude d'un codage particulier des donnees : le codage octree. Son adaptation a la manipulation de volumes numeriques est discutee
30
Braschi, Cécilia. "Espaces construits : abstraction et synthèse des arts au Brésil, autour des revues d'André Bloc (1930-1960)." Thesis, Paris 1, 2019. http://www.theses.fr/2019PA01H036.
Анотація:
Cette thèse étudie les revues d’art et d’architecture en tant que lieux de construction discursive et instruments privilégiés de circulation transnationale. Elle prend comme cas d’étude les relations entre les scènes française et brésilienne dans la période 1930-1960, portant une attention particulière aux transformations qui suivent la fin de la Seconde Guerre mondiale, à la fois dans la production artistique et critique, dans la représentation réciproque des deux contextes culturels et dans la négociation de leur place dans le nouvel ordre géopolitique. Largement diffusées en Amérique du Sud, les revues fondées par André Bloc sont étroitement liées à son action militante en faveur de la synthèse des arts et de l’abstraction géométrique. Perçues en France, en époque de reconstruction, comme les moteurs d’un grand renouveau humaniste et universaliste, abstraction et synthèse des arts sont aussi au cœur des revues brésiliennes nées au début des années 1950, vouées à définir les qualités d’un art national authentique et moderne. Au gré des divers enjeux qui animent les deux scènes culturelles, une perspective décentrée et postoccidentaliste permet de mettre en lumière les acceptions différentes que le même vocabulaire théorique recouvre en Europe et en Amérique latine, contribuant à l’élaboration de récits de l’art et de l’architecture brésiliens divergents mais interdépendants. Espaces « construits », les revues se font ainsi le miroir de nouvelles cartographies, susceptibles de repenser les relations centre(s)-périphérie(s), là où les différents discours sur l’art et l’architecture préfigurent autant de modèles esthétiques, sociaux et politiquesThis dissertation investigates art and architecture journals as spaces of discursive construction and as privileged instruments of transnational circulation. Its focus are the relations between the Brazilian and French scenes from 1930 to 1960, with particular emphasis on the transformations undergone after the end of the Second World War, both in artistic and critical production, in the reciprocal representation of two different cultural contexts and in the negotiation of their places within the new geopolitical order. Widely distributed in South America, André Bloc’s journals are closely linked to his militancy in favour of the synthesis of the arts and of geometric abstraction. During post-war reconstruction in France, abstraction and synthesis of the arts are perceived as the driving forces of a great humanist and universalist renewal, and they are simultaneously at the core of the Brazilian journals launched in the early 1950s, which were engaged in defining the qualities of an authentic and modern national art. Following the various stakes at play in these two cultural scenes, a decentralized and post-Occidentalist perspective brings to light the different meanings attributed in Europe and in Latin America to the same theoretical vocabulary, contributing to the formulation of diverse but mutually dependent narratives concerning Brazilian art and architecture. As “constructed” spaces, the journals mirror new cartographies which furnish the basis for rethinking the relations between centre(s) and periphery(ies), while different discourses about art and architecture prefigure as many aesthetic, social and political models
31
Bordairon, Marc. "Dimensionnement des massifs en sol renforcé par géosynthétiques." Grenoble INPG, 1986. http://www.theses.fr/1986INPG0113.
Анотація:
Calcul des massifs de soutenement en terre renforcee par des nappes horizontales de geosynthetiques. Analyse detaillee d'une nouvelle "methode double blocs" et formalisee par une geometrie quelconque et des sollicitations diverses. Surface de glissement polygonale. Etude de l'influence de certains parametres (hauteur, sol, inclinaison du parement) sur le dimensionnement en vue de l'elaboration d'abaques de dimensionnement de massifs en sol renforce que l'on presente. Comparaison avec des methodes d'equilibre limite a surface de glissement circulaire. Resume des principales methodes traditionnelles pour des massifs a parements verticaux. Application de ces methodes sur des ouvrages de soutenement construits dans le departement de l'isere
32
Zamboj, Michal. "Syntetická projektivní geometrie." Doctoral thesis, 2018. http://www.nusl.cz/ntk/nusl-392456.
Анотація:
A synthetic approach to the construction of projective geometry, its methods and selected results are given in the proposed thesis. The main historical drawbacks of the original proof of Chasles's theorem for non-developable ruled surfaces and von Staudt's formalization of projective geometry are commented. The corre- sponding theoretical background is elaborated on visual demonstrations with the accent to interrelations of classical synthetic, axiomatic and analytic points of view. Synthetic methods of projective geometry and their mixture with analytic methods are described on examples including numerous alternative proofs and generalizations of some theorems. A method of four-dimensional visualization is introduced in details. Elementary constructions of images of points, lines, planes and 3-spaces are followed by models of polychora, their sections and shadows. Chasles's theorem is proven for non-developable ruled quadrics on synthetic vi- sualizations, then generalized and proven within the pure projective framework for algebraic surfaces. The synthetic classification of regular quadrics is derived from descriptive geometry constructions of sections of four-dimensional cones and analytically verified in the projective extension of the real space. An integral part of the thesis is a...
33
Sung, Cheng-Lun, and 宋正倫. "Geometric Recursive Pattern Synthesis." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/762y2b.
Анотація:
碩士國立臺北科技大學
資訊工程系
106
This study propose a Geometric Recursive Pattern Synthesis system, using the Planetary Surround Model to draw closed symmetrical geometric patterns. The system is based on HTML and Javascript. Users can quickly generate all kinds of geometric recursive patterns by adjusting different parameters. Then arrange, combine, color the generated patterns to create a perfect pattern work with personal style. In addition to the pattern synthesis, the generating process of the Planetary Surround Model can also be understood through animation playback.
34
AlMeraj, Zainab. "Synthesis and evaluation of geometric textures." Thesis, 2013. http://hdl.handle.net/10012/7872.
Анотація:
Two-dimensional geometric textures are the geometric analogues of raster (pixel-based) textures and consist of planar distributions of discrete shapes with an inherent structure.
These textures have many potential applications in art, computer graphics, and cartography.
Synthesizing large textures by hand is generally a tedious task. In raster-based synthesis, many algorithms have been developed to limit the amount of manual effort required. These algorithms take in a small example as a reference and produce larger similar textures using a wide range of approaches.
Recently, an increasing number of example-based geometric synthesis algorithms have been proposed. I refer to them in this dissertation as Geometric Texture Synthesis (GTS) algorithms. Analogous to their raster-based counterparts, GTS algorithms synthesize arrangements that ought to be judged by human viewers as “similar” to the example inputs.
However, an absence of conventional evaluation procedures in current attempts demands an inquiry into the visual significance of synthesized results.
In this dissertation, I present an investigation into GTS and report on my findings from three projects. I start by offering initial steps towards grounding texture synthesis techniques more firmly with our understanding of visual perception through two psychophysical studies. My observations throughout these studies result in important visual cues used by people when generating and/or comparing similarity of geometric arrangements as well a set of strategies adopted by participants when generating arrangements.
Based on one of the generation strategies devised in these studies I develop a new geometric synthesis algorithm that uses a tile-based approach to generate arrangements. Textures synthesized by this algorithm are comparable to the state of the art in GTS and provide an additional reference in subsequent evaluations.
To conduct effective evaluations of GTS, I start by collecting a set of representative examples, use them to acquire arrangements from multiple sources, and then gather them into a dataset that acts as a standard for the GTS research community. I then utilize this dataset in a second set of psychophysical studies that define an effective methodology for comparing current and future geometric synthesis algorithms.
35
Zambanini, Robert A. "Computer-aided tolerance analysis and synthesis tolls for slot/slider geometries /." Diss., 2000. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9982880.
36
Giansanti, Andrea. "Structural classification of proteins based on a synthetic geometric representation." Doctoral thesis, 2012. http://hdl.handle.net/11573/917613.
37
Rauch, Rene. "G-SOMO : an oversampling approach based on self-organized map oversampling and geometric SMOTE." Master's thesis, 2019. http://hdl.handle.net/10362/63811.
Анотація:
Dissertation presented as the partial requirement for obtaining a Master's degree in Data Science and Advanced AnalyticsTraditional supervised machine learning classifiers are challenged to learn highly skewed data distributions as they are designed to expect classes to equally contribute to the minimization of the classifiers cost function. Moreover, the classifiers design expects equal misclassification costs, causing a bias for underrepresented classes. Thus, different strategies to handle the issue are proposed by researchers. The modification of the data set managed to establish since the procedure is generalizable to all classifiers. Various algorithms to rebalance the data distribution through the creation of synthetic instances were proposed in the past. In this paper, we propose a new oversampling algorithm named G-SOMO, a method that is inspired by our previous research. The algorithm identifies optimal areas to create artificial data instances in an informed manner and utilizes a geometric region during the data generation to increase variability and to avoid correlation. Our experimental setup compares the performance of G-SOMO with a benchmark of effective oversampling methods. The oversampling methods are repeatedly validated with multiple classifiers on 69 datasets. Different metrics are used to compare the retrieved insights. To aggregate the different performances over all datasets, a mean ranking is introduced. G-SOMO manages to consistently outperform competing oversampling methods. The statistical significance of our results is proven.
38
Lin, Cheng-Yuan, and 林慶源. "Geometric Processing of Synthetic Aperture Radar Image Of Remotely Sensed Data." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/43295042889517684056.
Анотація:
碩士國立交通大學
控制工程系
84
Synthetic Aperture Radar (SAR) is an active microwave remote sensing systemregardless of the influence of weather and the time of detecting. It is a very important source of remote sensing data using SAR to acquire the high-resolution on imagery for general or military purposes. Due to the fact that the land changes rapidly and the cost is increased, the use of effective measuring techniques to survey the land has become more significant. This paper focuses on the precise determination of the satellite orbit parameters from the MPH (MainProduct Header) documented by ERS-1. The main features developed here is for the geometric calibraction of the remote sensing imagery, which contributes to thesatellite orbit precision. Furthermore, affer the preciser orbit parameters aredecided, the resampling imagery makes registration with the relief map. As acomplementary information, the data of the land can be appropriately justifed.
39
Heftler, Christopher Scott. "Kant’s analytic-geometric revolution : ostensive judgment as algebraic time–state relation in the Critique of pure reason." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-12-4950.
Анотація:
In the Critique of Pure Reason, Kant defends the mathematically deterministic world of physics by arguing that its essential features arise necessarily from innate forms of intuition and rules of understanding through combinatory acts of imagination. Knowing is active: it constructs the unity of nature by combining appearances in certain mandatory ways. What is mandated is that sensible awareness provide objects that conform to the structure of ostensive judgment: “This (S) is P.”
Sensibility alone provides no such objects, so the imagination compensates by combining passing point-data into “pure” referents for the subject-position, predicate-position, and copula. The result is a cognitive encounter with a generic physical object whose characteristics—magnitude, substance, property, quality, and causality—are abstracted as the Kantian categories. Each characteristic is a product of “sensible synthesis” that has been “determined” by a “function of unity” in judgment.
Understanding the possibility of such determination by judgment is the chief difficulty for any rehabilitative reconstruction of Kant’s theory. I will show that Kant conceives of figurative synthesis as an act of line-drawing, and of the functions of unity as rules for attending to this act. The subject-position refers to substance, identified as the objective time-continuum; the predicate-position, to quality, identified as the continuum of property values (constituting the second-order type named by the predicate concept). The upshot is that both positions refer to continuous magnitudes, related so that one (time-value) is the condition of the other (property-value).
Kant’s theory of physically constructive grammar is thus equivalent to the analytic-geometric formalism at work in the practice of mathematical physics, which schematizes time and state as lines related by an algebraic formula. Kant theorizes the subject–predicate relation in ostensive judgment as an algebraic time–state function. When aimed towards sensibility, “S is P” functions as the algebraic relation “t → ƒ(t).”text
40
Shiping, Liu. "Synthetic notions of curvature and applications in graph theory." Doctoral thesis, 2012. https://ul.qucosa.de/id/qucosa%3A11816.
Анотація:
The interaction between the study of geometric and analytic aspects of Riemannian manifolds and that of graphs is a very amazing subject. The study of synthetic curvature notions on graphs adds new contributions to this topic. In this thesis, we mainly study two kinds of synthetic curvature notions: the Ollivier-Ricci cuvature on locally finite graphs and the combinatorial curvature on infinite semiplanar graphs.
In the first part, we study the Ollivier-Ricci curvature. As known in Riemannian geometry, a lower Ricci curvature bound prevents geodesics from diverging too fast on average. We translate this Riemannian idea into a combinatorial setting using the Olliver-Ricci curvature notion. Note that on a graph, the analogue of geodesics starting in different directions, but eventually approaching each other again, would be a triangle. We derive lower and upper Ollivier-Ricci curvature bounds on graphs in terms of number of triangles, which is sharp for instance for complete graphs. We then describe the relation between Ollivier-Ricci curvature and the local clustering coefficient, which is an important concept in network analysis introduced by Watts-Strogatz.
Furthermore, positive lower boundedness of Ollivier-Ricci curvature for neighboring vertices imply the existence of at least one triangle. It turns out that the existence of triangles can also improve Lin-Yau\''s curvature dimension inequality on graphs and then produce an implication from Ollivier-Ricci curvature lower boundedness to the curvature dimension inequality.
The existence of triangles prevents a graph from being bipartite. A finite graph is bipartite if and only if its largest eigenvalue equals 2. Therefore it is natural that Ollivier-Ricci curvature is closely related to the largest eigenvalue estimates. We combine Ollivier-Ricci curvature notion with the neighborhood graph method developed by Bauer-Jost to study the spectrum estimates of a finite graph. We can always obtain nontrivial estimates on a non-bipartite graph even if its curvature is nonpositive. This answers one of Ollivier\''s open problem in the finite graph setting.
In the second part of this thesis, we study systematically infinite semiplanar graphs with nonnegative combinatorial curvature. Unlike the previous Gauss-Bonnet formula approach, we explore an Alexandrov approach based on the observation that the nonnegative combinatorial curvature on a semiplanar graph is equivalent to nonnegative Alexandrov curvature on the surface obtained by replacing each face by a regular polygon of side length one with the same facial degree and gluing the polygons along common edges.
Applying Cheeger-Gromoll splitting theorem on the surface, we give a metric classification of infinite semiplanar graphs with nonnegative curvature. We also construct the graphs embedded into the projective plane minus one point. Those constructions answer a question proposed by Chen.
We further prove the volume doubling property and Poincare inequality which make the running of Nash-Moser iteration possible. We in particular explore the volume growth behavior on Archimedean tilings on a plane and prove that they satisfy a weak version of relative volume comparison with constant 1.
With the above two basic inequalities in hand, we study the geometric function theory of infinite semiplanar graphs with nonnegative curvature. We obtain the Liouville type theorem for positive harmonic functions, the parabolicity. We also prove a dimension estimate for polynomial growth harmonic functions, which is an extension of the solution of Colding-Minicozzi of a conjecture of Yau in Riemannian geometry.
41
Kreslová, Iva. "Analytický a syntetický přístup k řešení metrických úloh v prostoru." Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-404938.
Анотація:
The diploma thesis deals with metric tasks in space, using synthetic and analytical geometry. In addition to explaining the different approaches, there is a set of examples to practice. The solution of the examples is part of the Portal of High School Mathematics (Portál středoškolské matematiky), where we can and analytical solutions, synthetic numerical solutions and synthetic constructional solutions.
42
Bartlett, Malcolm Alan. "Synthesis and characterisation of novel oxovanadium(IV) Schiff base complexes: A study of their electronic spectral properties, peroxide binding affinities, DFT-calculated geometries and spectra, and cytotoxicity towards human carcinoma cells." Thesis, 2012. http://hdl.handle.net/10413/8894.
Анотація:
A series of five, tetradentate Schiff-base ligands were synthesised and chelated to vanadyl to form
oxovanadium(IV) complexes. The ligands, 4,4’-{benzene-1,2-diylbis[nitrilo(1E)phen-1-yl-1ylidene]}-
dibenzene-1,3-diol (H2L1), 4,4’-{ethane-1,2-diylbis[nitrilo(1E)phenyl-1-yl-1-ylidene]}dibenzene-1,3-diol
(H2L2), 4,4’-{propane-1,2-diylbis[nitrilo(1E)phen-1-yl-1-ylidene]}dibenzene-1,3-diol (H2L3), 4,4’-{(2-
hydroxypropane-1,3-diyl)bis[nitrilo(1E)phen-1-yl-1-ylidene]}dibenzene-1,3-diol (H2L4) and 4,4’-{2,2-
dimethylpropane-1,3-diyl)bis-[nitrilo(1E)phen-1-yl-1-ylidene]}-dibenzene-1,3-diol (H2L5), characterised by
TOF-MS, IR, electronic absorption, 1H and 13C NMR spectroscopy. The ligand H2L5 was also characterised
by XRD. The ligands were shown to have a bis-zwitterionic structure in the solid state, and possibly also in
solution. Complexes were characterised by Elemental Analysis, TOF-MS, IR, electronic absorption spectra,
EPR and 51V NMR spectroscopy. They form mononuclear complexes, with one ligand binding a single
vanadyl ion.
EPR spectroscopy was performed on both the powdered form and solutions of the complexes. All the
complexes displayed axial symmetry, with increasing distortion from an ideal square pyramidal geometry
as the size and bulk of the central chelate ring was increased. Isotropic g0 values suggest solvent
interaction with the vanadium ion for the coordinating solvent DMSO. Additional distortion on the
coordination geometry, presumably from the benzyl groups of the compounds, causes the isotropic
hyperfine coupling constants to be greater than expected.
Furthermore, the ability of the complexes to bind peroxide species was investigated by following the
addition of H2O2 to the complexes using 51V NMR spectroscopy to observe shielding changes at the
vanadium nucleus, and 1H NMR spectroscopy to monitor the bulk magnetic susceptibility, via a modified
Evan’s NMR method. Similar experiments were done with sodium hydroxide for comparison. As expected,
the oxoperoxovanadium(V) complexes were more stable than their progenitor oxovanadium(IV)
complexes. Additionally, increasing the distortion from the ideal pseudo square-pyramidal coordination
geometry for the vanadyl ion resulted in a greater increase in the apparent stability of the peroxocomplexes.
This latter effect is further enhanced by the addition of a hydrogen-bonding group in close
proximity to the vanadium nucleus.
DFT calculations of the optimized geometries, natural bond orbitals, electronic absorption and infra-red
frequencies were performed for both the ligands and the complexes; nuclear magnetic resonance
calculations were performed for the ligands as well. The B3LYP/6-311G (d,p) and B3LYP/LANL2DZ level of
theories were used for the ligands and complexes respectively, except for electronic transitions, which
were calculated using TD-SCF methods for both ligands and complexes. Calculated and experimental
results were compared where possible, and showed reasonable agreement for all calculations performed.
The exception to this was for the NMR calculations for the ligands, which were poorly simulated.
Finally, the in vitro biological activity of the complexes was evaluated for cytotoxicity against the human
tumour cell lines: A549, U251, TK-10 and HT29, via an MTT assay. All complexes showed promising
anticancer activity, as evidenced by their low IC50 values for the cell lines A549, U251 and TK-10, which are
in general, lower than that observed for cisplatin. They did, however, express negligible activity against
the HT29 colon adenocarcinoma cell line; showing an apparent selectivity for certain cell lines. These
oxovanadium(IV) complexes, thus warrant further evaluation as chemotherapeutic agents.Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.