Дисертації з теми "Energy curvature"
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Ligo, Richard G. "Conformal transformations, curvature, and energy." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5550.
Повний текст джерелаVikström, Anton. "Curvature-Induced Energy Band Tilting in Finite-Length Carbon Nanotubes." Thesis, Umeå universitet, Institutionen för fysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-49673.
Повний текст джерелаEnergibandstrukturen för kolnanorör ges av tvärsnitt av grafens Dirac-koner nära K- och K'-punkterna. Medelst andra ordningens störningsteori och en tight-binding-modell med närmaste-granne-approximationen härleds de kurvaturinducerade korrektionerna till den grafenbaserade effektiva modellen. Utöver det redan kända Dirac-punkt-skiftet så visas kurvaturen orsaka inte bara en förvrängning av Dirac-konen, liktydigt med en mild kompression och en korrektion till den övergripande fermihastigheten, utan också en lutning av Dirac-konen och de associerade nanorörsenergibanden. Denna lutning resulterar i en hastighetsasymmetri för vänster- och högergående vågor och två olika sorters excitationer, vilket tillåter för varierande degeneration i samma prov. Tidigare experiment har visat oregelbundenheter i nivådegenerationen och bör omprövas i denna kontext.
Venkataraman, Kartik. "Animating skin with wrinkles using curvature evolution and energy minimization /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2008. http://uclibs.org/PID/11984.
Повний текст джерелаKuyrukcu, Halil. "Kaluza-klein Reduction Of Higher Curvature Gravity Models." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611748/index.pdf.
Повний текст джерелаVincent, Aaron. "Curvature spectra and nongaussianities in the Roulette Inflation model of the early universe." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21998.
Повний текст джерелаNous etudions le modele d'inflation de type "Roulette", un modele base sur la relaxation de modules de Kahler sur une variete Calabi-Yau, ayant un terme cinetique non-trivial et provenant de la theorie des cordes de Type IIB, dans le contexte de la compactification a grand volume. Nous demontrons que l'influence des perturbations d'entropie peuvent compter pour jusqu'a 90% de Ps(k) a l'echelle de COBE. Nous demontrons que le resultat effectif provenant de la theorie a un seul champ surestime ns; un calcul complet predit un spectre decale vers le rouge 0.92 < ns < 0.98. Nous calculons finalement la non-gaussianite des perturbations adiabatiques resultant de leur evolution a l'exterieur du rayon de Hubble, et arrivons a des predictions de fNL ≪ 1, ce qui ne serait pas mesurable par les observations des prochaines annees. Toutefois, s'il s'avere possible de detecter un bispectre dependant du nombre d'onde k, ceci servirait d'excellent moyen de diff´erentier divers modeles d'inflation.
Khoo, Bee Jin. "An experimental examination of ideas in the curvature elasticity of lyotropic liquid crystals." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244046.
Повний текст джерелаLutman, Alberto. "Impact of the wakefields and of an initial energy curvature on a Free Electron Laser." Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3678.
Повний текст джерелаFor an X-ray free electron laser (FEL), a high-quality electron bunch with low emittance, high peak current and energy is needed. During the phases of acceleration, bunch compression and transportation, the electron beam is subject to radio frequency curvature and to wakefields effects. Thus, the energy profile of the electron beam can present a parabolic profile, which has important electromagnetic effects on the FEL process. The quality of the electron beam is also degraded by the interaction with the low-gap undulator vacuum chamber. In our work we first analyze this interaction, deriving a formula to evaluate the longitudinal and the transversal wakefields for an elliptical cross section vacuum chamber, obtaining accurate results in the short range. Subsequently within the Vlasov-Maxwell one-dimensional model, we derive the Green functions necessary to evaluate the radiation envelope, having as initial conditions both an energy chirp and curvature on the electrons and eventually an initial bunching, which is useful to treat the harmonic generation FEL cascade configuration. This allows to study the impact of the elecron beam energy profile on the FEL performance. Using the derived Green functions we discuss FEL radiation properties such as bandwidth, frequency shift, frequency chirp and velocity of propagation. Finally, we propose a method to achieve ultra-short FEL pulses using a frequency chirp on the seed laser and a suitable electron energy profile.
XXII Ciclo
1980
Melo, Marcelo Ferreira de. "Funcionais paramÃtricos elÃpticos em variedades riemannianas." Universidade Federal do CearÃ, 2009. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=4102.
Повний текст джерелаConselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Neste trabalho, consideramos funcionais paramÃtricos elÃpticos como generalizaÃÃes naturais para o clÃssico funcional Ãrea. Calculamos a primeira variaÃÃo de tais funcionais e, a partir da equaÃÃo de Euler-Lagrange, definimos a curvatura mÃdia anisotrÃpica de uma hipersuperfÃcie imersa em uma variedade Riemanniana como generalizaÃÃo natural da curvatura mÃdia usual. Em seguida, estabelecemos a fÃrmula da segunda variaÃÃo e classificamos as hipersuperfÃcies rotacionalmente simÃtricas que possuem curvatura mÃdia anisotrÃpica constante. A fim de compreender a estabilidade dos exemplo rotacionais,deduzimos a primeira e a segunda fÃrmulas de Minkowski. AlÃm disso, no contexto anisotrÃpico, apresentamos as equaÃÃes fundamentais de Weingarten, Codazzi e Gauss e, por fim, estudamos a harmonicidade da aplicaÃÃo de Gauss.
It is stated that critical points of a parametric elliptic functional in a Riemannian manifold are hypersurfaces with prescrebed anisotropic mean curvature. We prove that the anisotropic Gauss map of surfaces immersed in Euclidean space with constant anisotropic mean curvature is a harmonic map. In the case of rotatioally invariat functionals in some homogeneous three-dimensional ambients, we present a abridged version of a existence result for constant anisotropic mean curvature surfaces as cylinders, spheres, tori and annuli corresponding to the anisotropic analogs of onduloids and nodoids. In the Euclidean case M = R3, examples of stable critical points are provided by the Wulff shapes associated to functional F. Paralleling the case of constant curvature mean spheres, a characterization of Wulff shapes is provided, which answers affirmatively a question posed by M. Koiso and B. Parmer in [13].
Abdellatif, Ahmad Fouad Abdalwahab [Verfasser]. "On metric-affine gravitational theories with a Lagrangian quadratic in the curvature and the energy-momentum problem / Ahmad Fouad Abdalwahab Abdellatif." Greifswald : Universitätsbibliothek Greifswald, 2012. http://d-nb.info/1019426683/34.
Повний текст джерелаFilho, Francisco de Assiss Benjamim. "A partial answer to the CPE conjecture, diameter estimates and manifolds with constant energy." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14748.
Повний текст джерелаConselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Esta tese està dividida em quatro partes. Na primeira delas estudaremos pontos crÃticos do funcional curvatura escalar total restrito ao espaÃo das mÃtricas de curvatura escalar constante e volume unitÃrio. Provaremos que sob certas condiÃÃes integrais convenientes os pontos crÃticos de tal funcional sÃo variedades de Einstein provando assim a conjectura dos pontos crÃticos neste caso. Na segunda parte, veremos duas estimativas para o primeiro autovalor do Laplaciano de uma variedade compacta com curvatura de Ricci limitada por baixo por uma constante. As estimativas que obtemos melhoram a estimativa correspondente provada por Li e Yau (1980). Na terceira parte, estamos interessados em estimar o diÃmetro de hipersuperfÃcies mÃnimas da esfera. A estimativa que encontramos depende apenas do primeiro autovalor do Laplaciano da hipersuperfÃcie considerada. Para superfÃcies imersas na esfera de dimensÃo trÃs, obtemos uma estimativa ligeiramente melhor do que a obtida no caso de dimensÃo alta. Na Ãltima parte, introduzimos o conceito de variedade de energia constante e provamos que a esfera e o toro sÃo as Ãnicas superfÃcies que tÃm energia constante. Em dimensÃo mais alta a situaÃÃo à bem diferente uma vez que o produto de uma esfera por qualquer variedade compacta tem energia constante. Entretanto, se impusermos uma condiÃÃo sobre a curvatura de Ricci, à possÃvel caracterizar a esfera tambÃm neste caso. Em seguida, aplicamos as informa-ÃÃes obtidas ao estudo de hipersuperfÃcies da esfera provando alguns resultados de rigidez desde que a hipersuperfÃcie tenha energia constante.
This thesis is divided into four parts. In the first one we study the critical points of the total scalar curvature functional restricted to the space of metrics with constant scalar curvature and volume one. We shall prove that under certain suitable integral conditions the critical points of such functional are Einstein manifolds proving this way the critical point equation conjecture in this case. In the second part, we will provide an estimate for the first eigenvalue of the Laplacian of a compact manifolds with Ricci curvature bounded from below by a constant. The estimate we obtain improves the corresponding estimate proved by Li and Yau (1980). In the third part, we are interested in to estimate the diameter of minimal hypersurfaces of the sphere. The estimate we get depends only on the first eigenvalue of the Laplacian of the considered hypersurface. For immersed surfaces on the three dimensional sphere, we obtain an estimate slightly better than the one obtained in the case of higher dimension. In the last part, we introduce the concept of manifolds with constant energy and prove that the sphere and the torus are the only compact surfaces that have constant energy. For higher dimension, the situation is very different sine the product of the sphere with any compact manifold has constant energy. Nevertheless, if we impose a condition over the Ricci curvature it is possible to characterize the sphere also in this case. After that, we apply the informations obtained to the study of hypersurfaces of the sphere proving some rigidity results provided that the hypersurfaces has constant energy.
Chung, Hesson. "Curvature elastic energy analysis and simultaneous calorimetry and time-resolved x-ray diffraction of hydrated lipid and cholesterol-containing systems: lamellar and cubic mesophases /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487856906256823.
Повний текст джерелаSaroka, Vasil. "Theory of optical and THz transitions in carbon nanotubes, graphene nanoribbons and flat nanoclusters." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/28863.
Повний текст джерелаYahia-Cherif, Safir. "Robustesse des estimations des contraintes de l'énergie noire avec les futurs grands relevés cosmologiques." Electronic Thesis or Diss., Toulouse 3, 2020. http://www.theses.fr/2020TOU30327.
Повний текст джерелаSince the discovery of the acceleration of the expansion of the universe at the end of the 90s, the LambdaCDM model describing the properties of the universe with only six parameters, remains to this day in agreement with current observations. The discovery of the accelerating expansion of the universe revealed the existence of a new dark component of the universe: dark energy which constitutes 70% of the total density of the universe. In recent years, many experiments have been proposed with the aim of studying cosmic acceleration, and this thanks to various cosmological probes. For example the grouping of galaxies, supernovae, weak and strong gravitational lensing, the cosmic microwave background or clusters of galaxies. In order to quantify the performance of cosmological probes, the Dark Energy Task Force (DETF) defined a figure of merit metric as inversely proportional to the contour area given by the dark energy parameters omega 0, and omega a derived from the Chevallier-Polarski-Linder parametrization. We are currently entering an era of high precision with large Generation IV cosmological surveys: Euclid, DESI, LSST, and W-FIRST. Predicting the constraints and the factor of merit that a future experiment will bring (forecasts) has now become one of the main concerns of scientists, because in addition to predicting the performance of future surveys, forecasts help in their design. This work aims to provide quantitative estimates of the binding power of some main Generation IV statements (Euclid, DESI, and LSST) within the framework of the LambdaCDM model, but also for its extensions (models relaxing the dark energy parameters, and modified gravity models). This work also focuses on the numerical aspect of the statistical approaches used in the forecasts and presents methods ensuring the robustness of the results via analyzes of stability, convergence, and thanks to the comparisons between different possible approaches (Fisher formalism, and Monte-Carlo Markov-Chain). In this thesis, we show that performing cross-correlations between different cosmological probes considerably improves the figure of merit, in particular for Euclid, the gain being less important for LSST. However, the comparison of the readings shows that LSST will potentially be the Generation IV survey that will provide the greatest figure of merit, unlike DESI, which will be the least efficient survey. We also highlight that the multi-tracer analysis carried out on the different populations that DESI will observe does not allow a considerable gain on the constraints and the figure of merit if we compare to a simple single-tracer analysis
Tuken, Ahmet. "Quantifying Seismic Design Criteria For Concrete Buildings." Phd thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/12604907/index.pdf.
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Piovano, Paulo. "Evolution and Regularity Results for Epitaxially Strained Thin Films and Material Voids." Research Showcase @ CMU, 2012. http://repository.cmu.edu/dissertations/96.
Повний текст джерелаHussain, Jakir. "Three Essays on the Measurement of Productivity." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36194.
Повний текст джерелаCifuentes, Quintero Jenny Alexandra. "Development of a new technique for objective assessment of gestures in mini-invasive surgery." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0056/document.
Повний текст джерелаOne of the most difficult tasks in surgical education is to teach students what is the optimal magnitude of forces and torques to guide the instrument during operation. This problem becomes even more relevant in the field of Mini Invasive Surgery (MIS), where the depth perception is lost and visual field is reduced. In this way, the evaluation of surgical skills involved in this field becomes in a critical point in the learning process. Nowadays, this assessment is performed by expert surgeons observation in different operating rooms, making evident subjectivity issues in the results depending on the trainer in charge of the task. Research works around the world have focused on the development of the automated evaluation techniques, that provide an objective feedback during the learning process. Therefore, first part of this thesis describe a new method of classification of 3D medical gestures based on biomechanical models (kinematics). This new approach analyses medical gestures based on the smoothness and quality of movements related to the tasks performed during the medical training. Thus, gesture classification is accomplished using an arc length parametrization to compute the curvature for each trajectory. The advantages of this approach are mainly oriented towards time and location independence and problem simplification. The study included several gestures that were performed repeatedly by different subjects; these data sets were acquired, also, with three different devices. Second part of this work is focused in a classification technique based on kinematic and dynamic data. In first place, an empirical expression between movement geometry and kinematic data is used to compute a different variable called the affine velocity. Experiments carried out in this work show the constant nature of this feature in basic medical gestures. In the same way, results proved an adequate classification based on this computation. Parameters found in previous experiments were taken into account to study movements more complex. Likewise, affine velocity was used to perform a segmentation of pick and release tasks, and the classification stage was completed using an energy computation, based on dynamic data, for each segment. Final experiments were performed using six video cameras and an instrumented laparoscope. The 3-D position of the end effector was recorded, for each participant, using the OptiTrack Motive Software and reflective markers mounted on the laparoscope. Force and torque measurements, on the other hand, were acquired using force and torque sensors attached to the instrument and located between the tool tip and the handle of the tool in order to capture the interaction between participant and the manipulated material. Results associated to these experiments present a correlation between the energy values and the surgical skills of the participants involved in these experiments
Cobo, Rafael Figueiredo. "O escalar de curvatura e a energia livre de Frank." Universidade Estadual de Londrina. Centro de Ciências Exatas. Programa de Pós-Graduação em Física, 2014. http://www.bibliotecadigital.uel.br/document/?code=vtls000193093.
Повний текст джерелаIn this work it is shown that the elastic constants are connected by a relation obtained from the calculation of the scalar curvature of a nematic liquid crystal with a not homogeneous director field, and the relationship between the scalar and the Free Energy of Frank. The relationship between the calculated elastic constants provides a theoretical result that has a constant feature, from experimental data for K11, K22 and K33 was possible to realize a graphic record allowing a study of the relationship found. This analysis showed that the relationship for the elastic constants have a close behavior to the theoretical value expected when near to the phase transition liquid-isotropic However, this behavior does not occur throughout the nematic mesophase, yet, this result is still expressive, seen that was found a relation that connects the elastic constants obtained from geometric parameters, which excludes the need of an additional hypothesis about the interactions between the constituents of the sample.
Chillara, Venkata Siva Chaithanya. "Multifunctional Laminated Composites for Morphing Structures." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524104865278235.
Повний текст джерелаLaadhari, Aymen. "Modélisation numérique de la dynamique des globules rouges par la méthode des fonctions de niveau." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00598251.
Повний текст джерелаGamero, Alessandra Costa 1981. "Desempenho operacional de um subsolador de hastes com curvatura lateral ("Paraplow"), em função de diferentes velocidades de deslocamento e profundidades de trabalho /." Botucatu : [s.n.], 2008. http://hdl.handle.net/11449/90467.
Повний текст джерелаBanca: Elcio Hiroyoshi Yano
Banca: Paulo Roberto Arbex Silva
Resumo: A compactação do solo afeta o desenvolvimento das plantas, bem como pode interferir nos níveis de produtividade das culturas. Com o intuito de diminuir o grau de compactação do solo, operações de manejo, como a subsolagem, que visam o rompimento da camada subsuperficial compactada, são realizadas. Este trabalho teve como objetivo estudar o desempenho operacional de um subsolador de hastes com curvatura lateral ("paraplow"), operando a diferentes velocidades de deslocamento do trator e profundidades de trabalho, bem como, avaliar o consumo energético demandado na operação. O experimento foi conduzido na Fazenda Experimental Lageado, pertencente à Faculdade de Ciências Agronômicas - Campus de Botucatu/UNESP, no ano de 2007. O solo da área experimental foi classificado como Nitossolo Vermelho Distroférrico, textura muito argilosa. O delineamento experimental utilizado foi em blocos casualizados e esquema fatorial 3 x 2, com quatro repetições. Os tratamentos foram compostos da combinação de três velocidades de deslocamento definidas em função do escalonamento de marchas do trator utilizado (A1, A2 e B1) e duas profundidades de trabalho do equipamento utilizado para a mobilização do solo (0,25 e 0,35 m). Foram avaliados os dados referentes à mobilização do solo, patinagem dos rodados, capacidade de campo, consumo de combustível, força e potência na barra de tração do trator. Os resultados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey a 5% de probabilidade. Osresultados obtidos permitiram chegar às seguintes conclusões: a) Após a regulagem em condições estáticas, o subsolador manteve as profundidades da subsolagem durante a operação em condições de campo; b) a velocidade de deslocamento não apresentou efeito significativo sobre a área de solo mobilizado; c) a velocidade de deslocamento e a capacidade de campo... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The soil compactness affects the development of the plants, as well as it can interferes in the levels of productivity of the crops. Some soil management operations, like the subsoiling, aims at the breakage of the soil compacted layer. Those operations are made with the purpose to reduce the soil compactness. This research had the objective of studying the operational performance of a subsoiler with a lateral bending (paraplow), operating to different displacement speeds and depths of work, as well as, valuing the demanded energetic consumption in the operation. The experiment carried out in the Experimental Farm Lageado, Agronomic Sciences College in the¨Julio de Mesquita Filho" University (UNESP) - Botucatu Campus /UNESP, in the year of 2007. The soil of experimental area was classified like "Nitossolo Vermelho Distroférrico", very clay texture. The experimental design was in 3x2 factorial scheme using randomized blocks with four replications. The treatments were composed of the combination of three displacement speeds defined in function of the scheduling of marches of the tractor (A1, A2 and B1) and two work depths of the equipment used for the mobilization of the soil (0,25 and 0,35 m). The works depths were obtained by changing the height of the support of the wheel of the subsoiler, There were valued the data referring to the mobilization of the soil, tractor wheel slip, capacity of field, fuel consumption , strength and power at the bar of traction of the tractor. The results were subjected to variance analysis and the averages compared by Tukey test at 5 % of probability. The gotten results had allowed to arrive at the following conclusions: a) After adjustment in static conditions, the subsoiler maintained the depths of the subsoiling during the operation in field conditions; b) the speed of displacement did not present significant effect on the mobilized area;... (Complete abstract click electronic access below)
Mestre
Gamero, Alessandra Costa [UNESP]. "Desempenho operacional de um subsolador de hastes com curvatura lateral (“Paraplow”), em função de diferentes velocidades de deslocamento e profundidades de trabalho." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/90467.
Повний текст джерелаCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A compactação do solo afeta o desenvolvimento das plantas, bem como pode interferir nos níveis de produtividade das culturas. Com o intuito de diminuir o grau de compactação do solo, operações de manejo, como a subsolagem, que visam o rompimento da camada subsuperficial compactada, são realizadas. Este trabalho teve como objetivo estudar o desempenho operacional de um subsolador de hastes com curvatura lateral (“paraplow”), operando a diferentes velocidades de deslocamento do trator e profundidades de trabalho, bem como, avaliar o consumo energético demandado na operação. O experimento foi conduzido na Fazenda Experimental Lageado, pertencente à Faculdade de Ciências Agronômicas - Campus de Botucatu/UNESP, no ano de 2007. O solo da área experimental foi classificado como Nitossolo Vermelho Distroférrico, textura muito argilosa. O delineamento experimental utilizado foi em blocos casualizados e esquema fatorial 3 x 2, com quatro repetições. Os tratamentos foram compostos da combinação de três velocidades de deslocamento definidas em função do escalonamento de marchas do trator utilizado (A1, A2 e B1) e duas profundidades de trabalho do equipamento utilizado para a mobilização do solo (0,25 e 0,35 m). Foram avaliados os dados referentes à mobilização do solo, patinagem dos rodados, capacidade de campo, consumo de combustível, força e potência na barra de tração do trator. Os resultados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey a 5% de probabilidade. Osresultados obtidos permitiram chegar às seguintes conclusões: a) Após a regulagem em condições estáticas, o subsolador manteve as profundidades da subsolagem durante a operação em condições de campo; b) a velocidade de deslocamento não apresentou efeito significativo sobre a área de solo mobilizado; c) a velocidade de deslocamento e a capacidade de campo...
The soil compactness affects the development of the plants, as well as it can interferes in the levels of productivity of the crops. Some soil management operations, like the subsoiling, aims at the breakage of the soil compacted layer. Those operations are made with the purpose to reduce the soil compactness. This research had the objective of studying the operational performance of a subsoiler with a lateral bending (paraplow), operating to different displacement speeds and depths of work, as well as, valuing the demanded energetic consumption in the operation. The experiment carried out in the Experimental Farm Lageado, Agronomic Sciences College in the¨Julio de Mesquita Filho” University (UNESP) – Botucatu Campus /UNESP, in the year of 2007. The soil of experimental area was classified like “Nitossolo Vermelho Distroférrico”, very clay texture. The experimental design was in 3x2 factorial scheme using randomized blocks with four replications. The treatments were composed of the combination of three displacement speeds defined in function of the scheduling of marches of the tractor (A1, A2 and B1) and two work depths of the equipment used for the mobilization of the soil (0,25 and 0,35 m). The works depths were obtained by changing the height of the support of the wheel of the subsoiler, There were valued the data referring to the mobilization of the soil, tractor wheel slip, capacity of field, fuel consumption , strength and power at the bar of traction of the tractor. The results were subjected to variance analysis and the averages compared by Tukey test at 5 % of probability. The gotten results had allowed to arrive at the following conclusions: a) After adjustment in static conditions, the subsoiler maintained the depths of the subsoiling during the operation in field conditions; b) the speed of displacement did not present significant effect on the mobilized area;... (Complete abstract click electronic access below)
Benjamim, Filho Francisco de Assis. "Uma resposta parcial para a conjectura CPE, estimativas de diâmetro e variedades com energia constante." reponame:Repositório Institucional da UFC, 2015. http://www.repositorio.ufc.br/handle/riufc/13041.
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This thesis is divided into four parts. In the first one we study the critical points of the total scalar curvature functional restricted to the space of metrics with constant scalar curvature and volume one. We shall prove that under certain suitable integral conditions the critical points of such functional are Einstein manifolds proving this way the critical point equation conjecture in this case. In the second part, we will provide an estimate for the first eigenvalue of the Laplacian of a compact manifolds with Ricci curvature bounded from below by a constant. The estimate we obtain improves the corresponding estimate proved by Li and Yau (1980). In the third part, we are interested in to estimate the diameter of minimal hypersurfaces of the sphere. The estimate we get depends only on the first eigenvalue of the Laplacian of the considered hypersurface. For immersed surfaces on the three dimensional sphere, we obtain an estimate slightly better than the one obtained in the case of higher dimension. In the last part, we introduce the concept of manifolds with constant energy and prove that the sphere and the torus are the only compact surfaces that have constant energy. For higher dimension, the situation is very different sine the product of the sphere with any compact manifold has constant energy. Nevertheless, if we impose a condition over the Ricci curvature it is possible to characterize the sphere also in this case. After that, we apply the informations obtained to the study of hypersurfaces of the sphere proving some rigidity results provided that the hypersurfaces has constant energy.
Esta tese está dividida em quatro partes. Na primeira delas estudaremos pontos críticos do funcional curvatura escalar total restrito ao espaço das métricas de curvatura escalar constante e volume unitário. Provaremos que sob certas condições integrais convenientes os pontos críticos de tal funcional são variedades de Einstein provando assim a conjectura dos pontos críticos neste caso. Na segunda parte, veremos duas estimativas para o primeiro autovalor do Laplaciano de uma variedade compacta com curvatura de Ricci limitada por baixo por uma constante. As estimativas que obtemos melhoram a estimativa correspondente provada por Li e Yau (1980). Na terceira parte, estamos interessados em estimar o diâmetro de hipersuperfícies mínimas da esfera. A estimativa que encontramos depende apenas do primeiro autovalor do Laplaciano da hipersuperfície considerada. Para superfícies imersas na esfera de dimensão três, obtemos uma estimativa ligeiramente melhor do que a obtida no caso de dimensão alta. Na última parte, introduzimos o conceito de variedade de energia constante e provamos que a esfera e o toro são as únicas superfícies que têm energia constante. Em dimensão mais alta a situação é bem diferente uma vez que o produto de uma esfera por qualquer variedade compacta tem energia constante. Entretanto, se impusermos uma condição sobre a curvatura de Ricci, é possível caracterizar a esfera também neste caso. Em seguida, aplicamos as informações obtidas ao estudo de hipersuperfícies da esfera provando alguns resultados de rigidez desde que a hipersuperfície tenha energia constante.
Meunier, Elisa. "Symétries, courants et holographie des spins élevés." Phd thesis, Université François Rabelais - Tours, 2012. http://tel.archives-ouvertes.fr/tel-00797863.
Повний текст джерелаHUANG, CHIH-FENG, and 黃志峰. "Innovative Design of Cassegrain Solar Concentrator System Utilizing Petzval Curvature to Enhance the Efficiency of Sunlight Energy." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/39296268835746354910.
Повний текст джерела國立臺灣科技大學
電子工程系
94
The applications of solar energy have received a great attention because of the energy crisis and the respect to the environmental thinking. However, the photoelectric energy transform is high cost but low efficiency. To solve this problem, holographic optical elements (HOEs) are used with Petzval Curvature applied to enhance the efficiency of sunlight concentration in the solar cell energy transforming system. This research presents the sunlight concentration performance improvement by applying Petzval Curvature on HOEs used with solar cells. A flashlight is used on a convex lens to simulate the parallel sunlight source. With a 60 to 120 degrees angle, the CdS set, which is positioned by Petzval Curvature, is placed within an effective focal length behind the convex lens. This study measures the energy distribution by testing the placed CdS with software simulation analysis. The research shows the performance of sunlight concentration is improved about 9% if the solar cells can be positioned based on Petzval Curvature. The advantages of applying Petzval Curvature are simple and low cost, which shows its potential on more applications.
VILLANI, MATTIA. "THE DARK SECTOR AS A METROLOGY EFFECT effects of the trace of the extrinsic curvature of 3-space on the dark side of the universe." Doctoral thesis, 2015. http://hdl.handle.net/2158/1088155.
Повний текст джерелаChang, Hung-Chih, and 張宏誌. "The Blank Optimum Design of a Cylindrical Cup Drawing and the Springback Prediction of Double-Curvature Surfaces Stamping Using Energy Method." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/75215386038019775112.
Повний текст джерела國立高雄應用科技大學
模具工程系碩士班
95
In this study, the energy method is adopted to obtain the optimum blank design of a cylindrical cup deep drawing and predict the springback of a stamped part with double curvatures. A systematic design method of sheet metal forming process is finally developed. Both of the energy method and uniform deformation theory are adopted to create the bound of initial blank design, a fourth-order Bezier curve is created automatically to describe this blank profile. The Taguchi method has been applied to study the effect of the design parameters including the control points of Bezier curve and the anisotropy of material. The integration of FEM simulation and the Golden section method updates the control points of Bezier curve to obtain the final optimum blank profile. The springback of a double curvature stamped part is also studied via the proposed energy method considering the average normal anisotropy of material. The strain distributions are obtained via the minimization of energy consumption, the elastoplastic strain and stress analysis is followed to predict the springback of product. The effect of anisotropy on the springback is also discussed. The experiments of a cylindrical cup deep drawing and a double curvature part stamping are carried out. The strain and deformed geometry results of experiment and prediction are in good agreement. It shows the proposed method and the developed system are feasible and applicable. The developed image processing system is also capable of measuring product dimensions in an acceptable accuracy. The research results have demonstrated the proposed methods and the developed systems are capable of doing the integration of blank design, process analysis, and quality control of sheet metal forming.