Dissertations / Theses on the topic 'Conformal change of metric'
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Jones, Miranda Rose. "Conformal deformation of a conic metric." Thesis, Wichita State University, 2011. http://hdl.handle.net/10057/3996.
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The problem studied here focuses on a compact manifold M without boundary in which the Riemannian metric g is on Λ = M – {p1, p2,…,pκ}. Near the pi 's, g has a particular type of singularity in which locally M = (0, δ)x × Ywhere Y is a Riemannian manifold with metric h. Calculation techniques involving Christoffel symbols, scalar curvature, and the Lapalacian of the manifold are used to reduce the Yamabe equation to a system of partial differential equations. After assuming that a function u > 0 satisfying the Yamabe equation exists, the most singular partial differential equation is solved using integration techniques to find necessary conditions on Y and h. Also studied in this paper are the conditions on Y and h for which M is already a manifold with constant scalar curvature.Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Mathematics and Statistics.
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ANSELLI, ANDREA. "PHI-CURVATURES, HARMONIC-EINSTEIN MANIFOLDS AND EINSTEIN-TYPE STRUCTURES." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/703786.
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The aim of this thesis is to study the geometry of a Riemannian manifold M, with a special structure, called Einstein-type structure, depending on 3 real parameters, a smooth map phi into a target Riemannian manifold N, and a smooth function, called potential function, on M itself. We will occasionally let some of the parameters be smooth functions. The setting generalizes various previously studied situations:, Ricci solitons, almost Ricci-solitons, Ricci-harmonic solitons, quasi-Einstein manifolds and so on. By taking a constant potential function those structures reduces to harmonic-Einstein manifolds, that are a generalization of Einstein manifolds. The main ingredient of our analysis is the study of certain modified curvature tensors on M related to the map phi, called phi-curvatures, obtaining, for instance, their transformation laws under a conformal change of metric, and to develop a series of results for harmonic-Einstein manifolds that parallel those obtained for Einstein manifolds some times ago and also in the very recent literature. Einstein-type structures may be obtained, for some special values of the parameters involved, by a conformal deformation of a harmonic-Einstein manifold or even as the base of a warped product harmonic-Einstein manifold. The latter fact applies not only in the Riemannian but also in the Lorentzian setting and thus some Einstein-type structures are connected with solutions of the Einstein field equations, which are of particular interest in General Relativity. The main result of the thesis is the locally characterization, via a couple of integrability conditions and mild assumptions on the potential function, of Einstein-type structures with vanishing phi-Bach curvature (in the direction of the potential) as a warped product with harmonic-Einstein base and with an open real interval as fibre, extending in a very non trivial way a recent result for Bach flat Ricci solitons. Moreover the map phi depends only on the base of the warped product and not on the fibre . We also consider rigidity, triviality and non-existence results, both in the compact and non-compact cases. This is done via integral formulas and, in the non-compact case, via analytical tools, like the weak maximum principle and the classical results of Obata, Tashiro, Kanai.
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Ruth, Harry Leonard Jr. "Conformal densities and deformations of uniform loewner metric spaces." Cincinnati, Ohio : University of Cincinnati, 2008. http://www.ohiolink.edu/etd/view.cgi?ucin1210203872.
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Thesis (Ph.D.)--University of Cincinnati, 2008.Committee/Advisors: David Herron PhD (Committee Chair), David Minda PhD (Committee Member), Nageswari Shanmugalingam PhD (Committee Member). Title from electronic thesis title page (viewed Sep.3, 2008). Keywords: conformal density; uniform spaces; Loewner; quasisymmetry; quasiconofrmal. Includes abstract. Includes bibliographical references.
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RUTH, HARRY LEONARD JR. "Conformal Densities and Deformations of Uniform Loewner Metric Spaces." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1210203872.
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Simsir, Muazzez Fatma. "Conformal Vector Fields With Respect To The Sasaki Metric Tensor Field." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605857/index.pdf.
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On the tangent bundle of a Riemannian manifold the most natural choice of metric tensor field is the Sasaki metric. This immediately brings up the question of infinitesimal symmetries associated with the inherent geometry of the tangent bundle arising from the Sasaki metric. The elucidation of the form and the classification of the Killing vector fields have already been effected by the Japanese school of Riemannian geometry in the sixties. In this thesis we shall take up the conformal vector fields of the Sasaki metric with the help of relatively advanced techniques.
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Julian, Poranee K. "Geometric Properties of the Ferrand Metric." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353088820.
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Istrati, Nicolina. "Conformal structures on compact complex manifolds." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC054/document.
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Dans cette thèse on s’intéresse à deux types de structures conformes non-dégénérées sur une variété complexe compacte donnée. La première c’est une forme holomorphe symplectique twistée (THS), i.e. une deux-forme holomorphe non-dégénérée à valeurs dans un fibré en droites. Dans le deuxième contexte, il s’agit des métriques localement conformément kähleriennes (LCK). Dans la première partie, on se place sur un variété de type Kähler. Les formes THS généralisent les formes holomorphes symplectiques, dont l’existence équivaut à ce que la variété admet une structure hyperkählerienne, par un théorème de Beauville. On montre un résultat similaire dans le cas twisté, plus précisément: une variété compacte de type kählerien qui admet une structure THS est un quotient fini cyclique d’une variété hyperkählerienne. De plus, on étudie sous quelles conditions une variété localement hyperkählerienne admet une structure THS. Dans la deuxième partie, les variétés sont supposées de type non-kählerien. Nous présentons quelques critères pour l’existence ou non-existence de métriques LCK spéciales, en terme du groupe de biholomorphismes de la variété. En outre, on étudie le problème d’irréductibilité analytique des variétés LCK, ainsi que l’irréductibilité de la connexion de Weyl associée. Dans un troisième temps, nous étudions les variétés LCK toriques, qui peuvent être définies en analogie avec les variétés de Kähler toriques. Nous montrons qu’une variété LCK torique compacte admet une métrique de Vaisman torique, ce qui mène à une classification de ces variétés par le travail de Lerman. Dans la dernière partie, on s’intéresse aux propriétés cohomologiques des variétés d’Oeljeklaus-Toma (OT). Plus précisément, nous calculons leur cohomologie de de Rham et celle twistée. De plus, on démontre qu’il existe au plus une classe de de Rham qui représente la forme de Lee d’une métrique LCK sur un variété OT. Finalement, on détermine toutes les classes de cohomologie twistée des métriques LCK sur ces variétésIn this thesis, we are concerned with two types of non-degenerate conformal structures on a given compact complex manifold. The first structure we are interested in is a twisted holomorphic symplectic (THS) form, i.e. a holomorphic non-degenerate two-form valued in a line bundle. In the second context, we study locally conformally Kähler (LCK) metrics. In the first part, we deal with manifolds of Kähler type. THS forms generalise the well-known holomorphic symplectic forms, the existence of which is equivalent to the manifold admitting a hyperkähler structure, by a theorem of Beauville. We show a similar result in the twisted case, namely: a compact manifold of Kähler type admitting a THS structure is a finite cyclic quotient of a hyperkähler manifold. Moreover, we study under which conditions a locally hyperkähler manifold admits a THS structure. In the second part, manifolds are supposed to be of non-Kähler type. We present a few criteria for the existence or non-existence for special LCK metrics, in terms of the group of biholomorphisms of the manifold. Moreover, we investigate the analytic irreducibility issue for LCK manifolds, as well as the irreducibility of the associated Weyl connection. Thirdly, we study toric LCK manifolds, which can be defined in analogy with toric Kähler manifolds. We show that a compact toric LCK manifold always admits a toric Vaisman metric, which leads to a classification of such manifolds by the work of Lerman. In the last part, we study the cohomological properties of Oeljeklaus-Toma (OT) manifolds. Namely, we compute their de Rham and twisted cohomology. Moreover, we prove that there exists at most one de Rham class which represents the Lee form of an LCK metric on an OT manifold. Finally, we determine all the twisted cohomology classes of LCK metrics on these manifolds
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Champion, Daniel James. "Mobius Structures, Einstein Metrics, and Discrete Conformal Variations on Piecewise Flat Two and Three Dimensional Manifolds." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/145313.
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Spherical, Euclidean, and hyperbolic simplices can be characterized by the dihedral angles on their codimension-two faces. These characterizations analyze the Gram matrix, a matrix with entries given by cosines of dihedral angles. Hyperideal hyperbolic simplices are non-compact generalizations of hyperbolic simplices wherein the vertices lie outside hyperbolic space. We extend recent characterization results to include fully general hyperideal simplices. Our analysis utilizes the Gram matrix, however we use inversive distances instead of dihedral angles to accommodate fully general hyperideal simplices.For two-dimensional triangulations, an angle structure is an assignment of three face angles to each triangle. An angle structure permits a globally consistent scaling provided the faces can be simultaneously scaled so that any two contiguous faces assign the same length to their common edge. We show that a class of symmetric Euclidean angle structures permits globally consistent scalings. We develop a notion of virtual scaling to accommodate spherical and hyperbolic triangles of differing curvatures and show that a class of symmetric spherical and hyperbolic angle structures permit globally consistent virtual scalings.The double tetrahedron is a triangulation of the three-sphere obtained by gluing two congruent tetrahedra along their boundaries. The pentachoron is a triangulation of the three-sphere obtained from the boundary of the 4-simplex. As piecewise flat manifolds, the geometries of the double tetrahedron and pentachoron are determined by edge lengths that gives rise to a notion of a metric. We study notions of Einstein metrics on the double tetrahedron and pentachoron. Our analysis utilizes Regge's Einstein-Hilbert functional, a piecewise flat analogue of the Einstein-Hilbert (or total scalar curvature) functional on Riemannian manifolds.A notion of conformal structure on a two dimensional piecewise flat manifold is given by a set of edge constants wherein edge lengths are calculated from the edge constants and vertex based parameters. A conformal variation is a smooth one parameter family of the vertex parameters. The analysis of conformal variations often involves the study of degenerating triangles, where a face angle approaches zero. We show for a conformal variation that remains weighted Delaunay, if the conformal parameters are bounded then no triangle degenerations can occur.
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Gonzalez, Marco A. "A new change propagation metric to assess software evolvability." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44607.
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The development of software-intensive systems faces many challenges; one of the most important from an economic perspective is to reduce their maintenance costs. This thesis proposes a modified change propagation metric as a tool to assist the analysis of evolvability and maintainability of a software system and to ultimately support the reduction of its maintenance cost.
The technical complexity of software systems has a great impact on their ability to make increased functionality and adaptability to the environment possible. One approach to understand and master the complexity of large software systems, varying from thousands to millions of lines of source code, is through software architecture. This study examines a sample of software systems from the dependencies of their static structural view. The dependencies and their importance are expressed as a design structure matrix (DSM) that is used as an indicator to reflect the strength of dependence and connection among the different modules.
In this thesis, we propose a “modified change propagation” metric as a set of incremental improvements over the original Propagation Cost (PC) metric proposed by MacCormack (2008). Our improved metric uses dependencies weighted with strength to convey more information about the incidence of strongly connected relationships and it discounts weak dependencies. Moreover the original propagation metrics considered that the system should be acyclical; but we found that in practice a very few real systems are exempt of cycles. Furthermore, if cyclic dependencies are heavy rather than weak then these cycles should be treated differently. Finally, our metric is normalized to minimize the effect of both change in the total depth of the dependency graph, and increases in the size of the code.
Our modified change propagation metric can help software designers assess the maintainability of a software system at design time and over a proposed release sequence by comparing change propagation measures for different designs of software architecture. For instance, after refactoring. We validated our metric both on a system developed at UBC, and on several large open-source repositories for which we were able to obtain long release histories.
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Xu, Chao. "Non-conformal geometry on noncommutative two tori." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1566225527101998.
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Hai, Pham Minh, and Yasushi Yamaguchi. "CHARACTERIZING THE URBAN GROWTH OF HANOI, NAGOYA, AND SHANGHAI CITY USING REMOTE SENSING AND SPATIAL METRICS." IEEE, 2008. http://hdl.handle.net/2237/12105.
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Stone, Matthew Lee Cole. "Using design-based change orders as a lessons learned metric in university dormitory construction." Thesis, [Tuscaloosa, Ala. : University of Alabama Libraries], 2009. http://purl.lib.ua.edu/2158.
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Amacha, Inas. "Flot de Yamabe avec courbure scalaire prescrite." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0109/document.
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Cette thèse est consacrée à l'étude d'une famille des flots géométriques associés au problème de la courbure scalaire prescrite sur une variété riemannienne compacte. Plus précisément, si on désigne par (M,g0) une variété riemannienne compacte de dimension n≥3, et si F∈C∞ (M) est une fonction donnée, le problème de la courbure scalaire prescrite consiste à trouver une métrique g conforme à g0 telle que F soit sa courbure scalaire. Ce problème est équivalent à la résolution de l'EDP suivante :-4 (n-1)/(n-2) ∆u+R0 u=Fu((n+2)/(n-2 )) , u>0 , (E), Où R0 est la courbure scalaire de la métrique initiale g0 et ∆ est le laplacien associé à g0. Il s'agit d'une équation elliptique non-linéaire dont la difficulté principale provient du terme u((n+2)/(n-2 )). Hormis le cas de la sphère standard Sn , tous les travaux consacrés à l'étude de l'équation (E) sont basés sur la méthode variationnelle. Dans cette thèse, on développe une autre approche basée sur l'étude d'une famille de flots géométriques qui permet, entre autres, de résoudre l'équation (E). La question dépend bien entendu de la métrique initiale g0 et en particulier du signe de sa courbure scalaire R0. Les flots introduits sont des flots de gradient associés à deux fonctionnelles distinctes dépendant du signe de R0. La première partie de cette thèse est consacrée au cas R0<0 et dans la deuxième partie on traite le cas R0>0. Dans les deux cas, on démontre l'existence globale du flot et on étudie son comportement asymptotique à l'infiniThis thesis is devoted to the study of a family of geometric flows associated with the prescribed scalar curvature problem. More precisely, if we denote by (M,g0) a compact riemannian manifold with dimension n≥3, and if F∈C∞ (M) is a given function, the prescribed scalar curvature problem consists of finding a conformal metric g to g0 such that F is its scalar curvature. This problem is equivalent to the resolution of the following PDE : -4 (n-1)/(n-2) ∆u+R0 u=Fu((n+2)/(n-2 )) , u>0 , (E), Where R0 is the scalar curvature of the initial metric g0 and ∆ is the laplacian associated with g0.It is a nonlinear elliptic equation, whose the main difficulty comes from the term u((n+2)/(n-2 )). Apart from the case of the standard sphere Sn all the works that study the equation (E) are based on the variational method. In this thesis, we develop another approach based on the study of a family of geometric flows which allows to solve equation (E).The flows introduced are gradient flows associated with two distinct functional functions depending on the sign of R0.The first part of this thesis is devoted to the case R0<0 and in the second part we treat the case R0>0. In both cases, our aim is to proof the global existence of the flow and study its asymptotic behavior at infinity
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Mohanty, Sudeshna. "Evaluation Methods for Assessing Change in Vibration Response with Variation in Engine Mounting Configuration." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553251616841952.
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Levihn, Fabian. "Investments, system dynamics, energy management and policy : a solution to the metric problem of bottom-up supply curves." Doctoral thesis, KTH, Hållbarhet och industriell dynamik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161904.
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Today, issues such as climate change and increased competition for scarce resources puts pressure on society and firms to transform. Change is not easily managed though, especially not when relating to production or consumption of energy carriers such as district heating or electric power. These systems do not only have strong dynamics internally, but dynamics between multiple technological systems must sometimes be considered to effectively manage response and strategies in relation to change. During the early 1980s, an optimisation model founded on an expert-based approach was developed based on the partial equilibrium model to enable the evaluation of different actions to reach a target. This model — often referred to as marginal abatement cost curve (MACC) or conservation supply curve (CSC) — is used by academia, industry and policymakers globally. The model is applied for causes such as energy conservation and waste management, but also within the climate change context for optimising CO2 reductions and governmental policy. In this context, the model is used by actors such as the Intergovernmental Panel on Climate Change (IPCC), International Energy Agency (IEA) and World Bank, and by the consultancy firm McKinsey & Company, who use it extensively in different analysis. This model has many drawbacks in relation to managing interdependencies between different options, but more specifically the metric used for ranking options with a negative marginal cost has a design flaw leading to biased results. As a solution Pareto optimisation has been suggested, but is problematic given the dynamics within and between energy systems. The purpose of this compilation dissertation is to improve the ability for industry and policymakers to effectively manage change and reach set targets. In particular it develops our knowledge of how to account for option interdependency within and between technological systems. Furthermore, the ranking problem relating to expert-based least cost integrated planning is addressed. This dissertation also provides policy and managerial implications relating to the issues of energy conservation, CO2 abatement, and SOx and NOx reduction in relation to the district heating system in Stockholm. Implications are also provided for the interaction with other systems such as the Nordic electric power system.Klimatfrågan och konkurrens om knappa resurser medför ett förändringstryck på nationer och företag. Att hantera förändringar har aldrig varit enkelt, vilket är tydligt bland företag inom energisektorn såsom el och fjärrvärmeproducenter. Energisystemen dessa företag är del av har stark intern dynamik, men även dynamik mellan olika energisystem är vanligt. Detta måste tas i beaktande när strategier och planer för att hantera förändring utformas. Under början av 1980-talet skapades en optimeringsmodell baserad på den nationalekonomiska jämviktsmodellen för att kunna utvärdera olika specifika möjligheter att nå ett mål, t.ex. energibesparingar. Denna modell, som idag ofta benämns MACC (Marginal Abatement Cost Curves) eller CSC (Concervation Supply Curves), används idag av akademin, industrin och myndigheter inom områden så som energibesparingar, minskade CO2-utsläpp, sophantering och design av ekonomiska policyinstrument. De icke-akademiska användarna inkluderar FNs klimatorgan IPCC, IEA och Världsbanken. Även konsultfirman McKinsey&Company använder modellen regelbundet i olika studier. Tyvärr har modellen många begräsningar när det kommer till att hantera dynamiker mellan de specifika åtgärder som identifierats för att nå ett mål. Den allvarligast begränsningen utgörs dock av ett optimeringsfel som leder till felaktiga slutsatser om prioriteringen mellan de åtgärder som har en negativ marginalkostnad. Som en lösning på detta problem har pareto-optimering föreslagits, vilket denna avhandling dock visar är problematiskt på grund av de dynamiker som finns inom och mellan energisystem. Det övergripande syftet med denna avhandling är att förbättra möjligheten att hantera förändringar och nå uppsatta mål. Specifikt diskuteras hur beroenden mellan olika åtgärder för att nå det satta målet kan hanteras. Avhandlingen adresser även problemet att prioritera mellan åtgärder med negativ marginalkostnad. Utöver detta bidrar avhandlingen med praktiska implikationer för politiker, myndigheter och företag involverade i fjärrvärmeproduktion i Stockholm. Slutsatser dras kring energibesparingar och minskade utsläpp av CO2, SOx och NOx. Praktiska implikationer ges även för hur system som detta fjärrvärmesystem samverkar och interagerar med det nordiska elsystemet.
QC 20150414
Investments in energy efficiency and climate change abatement: revising marginal cost curves as an optimization model
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Angelo, Neide Pizzolato. "Uma abordagem para a detecção de mudanças em imagens multitemporais de sensoriamento remoto empregando Support Vector Machines com uma nova métrica de pertinência." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/111856.
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Esta tese investiga uma abordagem não supervisionada para o problema da detecção de mudanças em imagens multiespectrais e multitemporais de sensoriamento remoto empregando Support Vector Machines (SVM) com o uso dos kernels polinomial e RBF e de uma nova métrica de pertinência de pixels. A proposta metodológica está baseada na diferença das imagens-fração produzidas para cada data. Em imagens de cenas naturais essa diferença nas frações de solo e vegetação tendem a apresentar uma distribuição simétrica próxima à origem. Essa caracteristica pode ser usada para modelar as distribuições normais multivariadas das classes mudança e não-mudança. O algoritmo Expectation-Maximization (EM) é implementado com a finalidade de estimar os parâmetros (vetor de médias, matriz de covariância e probabilidade a priori) associados a essas duas distribuições. A seguir, amostras aleatórias e normalmente distribuidas são extraídas dessas distribuições e rotuladas segundo sua pertinência em uma das classes. Essas amostras são então usadas no treinamento do classificador SVM. A partir desta classificação é estimada uma nova métrica de pertinência de pixels. A metodologia proposta realiza testes com o uso de conjuntos de dados multitemporais de imagens multiespectrais Landsat-TM que cobrem a mesma cena em duas datas diferentes. A métrica de pertinência proposta é validada através de amostras de teste controladas obtidas a partir da técnica Change Vetor Analysis, além disso, os resultados de pertinência obtidos para a imagem original com essa nova métrica são comparados aos resultados de pertinência obtidos para a mesma imagem pela métrica proposta em (Zanotta, 2010). Baseado nos resultados apresentados neste trabalho que mostram que a métrica para determinação de pertinência é válida e também apresenta resultados compatíveis com outra técnica de pertinência publicada na literatura e considerando que para obter esses resultados utilizou-se poucas amostras de treinamento, espera-se que essa métrica deva apresentar melhores resultados que os que seriam apresentados com classificadores paramétricos quando aplicado a imagens multitemporais e hiperespectrais.This thesis investigates a unsupervised approach to the problem of change detection in multispectral and multitemporal remote sensing images using Support Vector Machines (SVM) with the use of polynomial and RBF kernels and a new metric of pertinence of pixels. The methodology is based on the difference-fraction images produced for each date. In images of natural scenes. This difference in the fractions of bare soil and vegetation tend to have a symmetrical distribution close to the origin. This feature can be used to model the multivariate normal distributions of the classes change and no-change. The Expectation- Maximization algorithm (EM) is implemented in order to estimate the parameters (mean vector, covariance matrix and a priori probability) associated with these two distributions. Then random and normally distributed samples are extracted from these distributions and labeled according to their pertinence to the classes. These samples are then used in the training of SVM classifier. From this classification is estimated a new metric of pertinence of pixel. The proposed methodology performs tests using multitemporal data sets of multispectral Landsat-TM images that cover the same scene at two different dates. The proposed metric of pertinence is validated via controlled test samples obtained from Change Vector Analysis technique. In addition, the results obtained at the original image with the new metric are compared to the results obtained at the same image applying the pertinence metric proposed in (Zanotta, 2010). Based on the results presented here showing that the metric of pertinence is valid, and also provides results consistent with other published in the relevant technical literature, and considering that to obtain these results was used a few training samples, it is expected that the metric proposed should present better results than those that would be presented with parametric classifiers when applied to multitemporal and hyperspectral images.
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Carrasco, Piaggio Matias. "Jauge conforme des espaces métriques compacts." Phd thesis, Université de Provence - Aix-Marseille I, 2011. http://tel.archives-ouvertes.fr/tel-00645284.
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L'objet principal de cette thèse est l'étude de la dimension conforme Ahlfors régulière ($\dim_{AR}X$) d'un espace métrique $X$. C'est un invariant numérique par quasisymétrie, introduit par P.\,Pansu, permettant la classification à quasi-isométrie près des espaces homogénes de courbure négative. Elle joue actuellement un rôle important en théorie géométrique des groupes et en dynamique conforme. A partir d'une suite de recouvrements d'un espace métrique compact $\left(X,d\right)$, on construit des distances de dimension contrôlée appartenant à la jauge conforme (Ahlfors régulière). On peut ainsi caractériser toutes les métriques de la jauge á homéomorphismes bi-Lipschitz prés. On montre comment calculer $\dim_{AR}X$ á partir de modules combinatoires en considérant un exposant critique $Q_N$. Comme conséquence de l'égalité $\dim_{AR}X=Q_N$, on obtient un critère général de dimension $1$. Les conditions sont données en termes de points de coupure locale de $X$. On donne par ailleurs des applications de ces résultats aux bords des groupes hyperboliques et aux ensembles de Julia des fractions rationnelles semihyperboliques.
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Michel, Benoît. "Invariants asymptotiques en géométrie conforme et géométrie CR." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20111/document.
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Cette thèse étudie l'utilisation de certains invariants asymptotiques en géométrie conforme et géométrie CR.La première partie est consacrée à la géométrie conforme. Nous calculons les premiers termes du développement asymptotique de la fonction de Green des opérateurs GJMS au voisinage de la diagonale, pour un facteur conforme normal au sens de Lee et Parker. Nous montrons que le terme constant de ce développement est covariant sous un changement de facteur conforme normal. Nous le rattachons à un invariant à l'infini de type masse ADM d'une métrique non compacte obtenue par projection stéréographique.La deuxième partie est consacrée à la géométrie CR. Nous calculons les premiers termes du développement asymptotique de la fonction de Green de l'opérateur de Yamabe CR au voisinage de sa singularité,dans le cas CR sphérique, et en dimension 3 dans une carte CR-normale au sens de Jerison et Lee, lorsque la constante de Yamabe-CR est strictement positive. Nous montrons la covariance pseudo-conforme du terme constant sous les changements de cartes respectivement CR-sphériques et CR-normales.La troisième partie donne une explication formelle à une annulation algébrique sur laquelle repose la définition de plusieurs invariants à l'infini de type masse ADM, qui n'avait pu jusqu'à présent qu'être constatée par un calcul directIn this thesis we study the use of some asymptotic invariants in conformal and CR geometry.The first chapter is devoted to conformal geometry. We compute an asymptotic expansion ofthe Green function of GJMS operators near the diagonal, for a normal conformal factorin the sense of Lee and Parker. We show that the constant term in this expansion is covariant through achange of normal conformal factor. We relate it to an invariant at infinity of the type of the ADM massof a non-compact metric obtained by some kind of stereographic projection.In the second chapter we study CR geometry. We compute the first terms of the asymptotic expansion of the Greenfunction of the Yamabe-CR operator near its singularity, when the Yamabe-CR constant is positive, in the CR-sphericalcase, and in dimension 3 in a CR-normal chart in the sense of Jerison and Lee.We show the pseudo-conformal covariance of the constant term in this asymptotic expansion through a change of spherical chart andof CR-normal chart respectively.In the third chapter we give a formal explanation to an algebraic cancellationon which the defintion of some invariants at infinity such as the ADM mass relies
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SILVA, VAGNER VIANA. "INDICATOR AND METRIC FOR ASSESSING THE DEGREE OF COMMITMENT OF LARGE CONSUMERS OF ELECTRICITY ACCORDING TO INTERNATIONALLY AGREED RECOMMENDATIONS TOWARDS SUSTAINABILITY AND MITIGATIONS AND ADAPTATION OF CLIMATE CHANGE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=24962@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
A dissertação tem por objetivo avaliar o grau de comprometimento de grandes consumidores de energia elétrica com preceitos da sustentabilidade e do preocupante fenômeno das mudanças climáticas. No contexto do comprometimento da política brasileira com o desenvolvimento sustentável, o trabalho revê os principais acordos e recomendações internacionais que visam a mitigação e adaptação às mudanças climáticas e sustentabilidade como subsídios metodológicos à construção de um questionário estruturado. O questionário foi aplicado junto aos grandes clientes da concessionária de energia elétrica do Rio de Janeiro, que atende 4,1 milhões de consumidores na média e alta tensão (68 porcento da população e 66 porcento do PIB do segundo estado economicamente mais desenvolvido do país). A pesquisa de campo realizada permitiu identificar, na visão das organizações participantes, as ações de sustentabilidade e as medidas empresariais de adaptação e mitigação do fenômeno estudado. À luz das melhores práticas e diretrizes internacionais, foi proposto um indicador e uma métrica para avaliar o grau de comprometimento à essas práticas e tendências. Os resultados da pesquisa, estratificados por classes de consumidores, permitem avaliar, com base nos consumos de energia, o preocupante nível de emissões de gases efeito estufa (tCO2eq) que resultam da geração da energia elétrica consumida pelos clientes da concessionária. Não obstante mais de 90 porcento das organizações terem considerado a sustentabilidade como oportunidade de negócios e diferencial competitivo para viabilizar nichos de mercado, os resultados da pesquisa indicam que, na média, é preocupante o baixo grau de comprometimento dos grandes usuários de energia elétrica com as medidas desejáveis de restrição às emissões.
In the context of global concerns related to climate change due to the alarming and unprecedented growth of greenhouse gas (GHG) emissions, the present study evaluates the commitment to emissions restrictions among large users of electricity produced by a utility company that serves 4.1 million consumers (68 percent of the population and 66 percent of the gross internal product for the second most economically developed Brazilian state), based on the proposed metrics and indicator. The present work reviews the primary international agreements and recommendations that aim to mitigate and adapt to climate change and sustainability, in light of the Brazilian commitment to the policy of sustainable development. A survey was developed for the participating organisations, which were classified by economic sector, to expose them to 18 issues that reflect worldwide guidelines on emission constraints. Based on their total energy consumption, the survey discusses the worrying level of GHG emissions (tonnes of equivalent carbon dioxide, tCO2eq) associated with the generation of the electricity consumed by the largest utility company customers. Although over 90 percent of the organisations considered sustainability to be both a business opportunity and a competitive differential that enables niche markets, the results of the present study indicated a low degree of commitment to the desired emission restrictions from the larger electricity consumers, on average.
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TEIXEIRA, MONTEIRO ANTONIO MANUEL. "ASSESSMENT OF ECOLOGICAL CONDITIONS OF PERMANENT MEADOWS IN THE ITALIAN ALPS: LOSS, BIODIVERSITY AND REMOTE SENSING CHANGE DETECTION." Doctoral thesis, Università degli Studi di Milano, 2011. http://hdl.handle.net/2434/152908.
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The monitoring of ecological condition of grasslands ecosystems in the
European Alps is a main issue for mountain regions, since the abandonment of
traditional and sustainable management practices has exposed grassland habitat
to significant impacts in a context of global environmental change.
The present research project was focused in assessment of the state of
permanent meadows in the lowlands of Valtellina Valley (80 km2), Italian Alps,
during the timeframe 1980-2000. In specific, it quantified the land use/land
cover changes and identified main drivers behind permanent meadows loss;
characterized the relationship between biodiversity in the meadows and the
spatial-environmental conditions in the landscape and by last evaluated the use
of satellite remote sensing data for fast change detection in landscape. To
achieve such aims, the research project was organized in three different
approaches presented in the four chapters of this thesis.
Concerning the quantification of the land use/land cover and identification of
main drivers behind permanent meadows loss, the results show a strong
decrease in meadows (-18.5%) in a context of agricultural land decrease and
human settlements increase. This was the land cover type with highest loss and
conversion rate during the study period. Meadows were converted to human
settlements (urban, industrial and roads), other agriculture uses (cultivation,
orchard, vineyard), bushland and uncultivated land. Meadows loss occurred
mainly in soils with good land capability, low slope, exposed to south and in
proximity of roads, urban settlements and bushland. Densities of urban,
industrial and bushland and land capability were the only significant drivers for
meadows loss, while distance to meadow edge, meadows density, distance to
roads and soil degradation were the only significant drivers for meadows
preservation.
Concerning the characterization of the relationship between biodiversity in the
meadows and the spatial-environmental conditions in the landscape, the results
evidenced that species richness and Shannon indices were best explained by
regressive models including changes occurred in spatial environmental
heterogeneity from 1980 to 2000. Species richness was negatively related to
strong decrease in meadows habitat area and recent urban area, while Shannon
index was positively related to the increase in landscape diversity. In contrast,
species evenness was better explained by regressive model including recent
spatial environmental heterogeneity and positively related to increase ineastness in the study area, and negatively affected both by the area of woody
and soil pH (KCl).
Concerning the evaluation of the use of satellite remotely sensing data for land
cover mapping and change detection in landscape, the results show that the
hybrid approach for land cover classification based of Landsat imagery was
highly accurate. Image differencing is the technique which best detect changes
in landscape as well as in urban, meadow and bush land. The accuracy of
change detection was moderate.
This thesis concludes that the conflict by land in locations densely occupied by
other land cover types with good land capability is the major threat to
meadows and avoidance of fragmentation may be a good strategy for its
preservation. The meadows habitat needs a well-designed landscape and
farming planning, which should account the economic value of the ecosystem
services provided by this habitat. In addition, to conserve plant diversity in
meadows it is necessary to avoid loss of meadows habitat, maintain landscape
diversity and execute a sustainable meadow management.
Remotely sensed imagery can be a reliable source of information for alps,
although particular attention should be made to the image pre-processing and
classification, as well as, to minimize topography effects in spectral
information.
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Kourganoff, Mickaël. "Géométrie et dynamique des espaces de configuration." Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL1049/document.
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Cette thèse est divisée en trois parties. Dans la première, on étudie des systèmes articulés (mécanismes formés de tiges rigides) dont l'espace ambiant n'est pas le plan, mais diverses variétés riemanniennes. On étudie la question de l'universalité des mécanismes : cette notion correspond à l'idée que toute courbe serait tracée par un sommet d'un mécanisme, et que toute variété différentiable serait l'espace de configuration d'un mécanisme. On étend les théorèmes d'universalité au plan de Minkowski, au plan hyperbolique et enfin à la sphère.Toute surface dans R^3 peut être aplatie selon l'axe des z, et la surface aplatie s'approche d'une table de billard dans R^2. Dans la seconde partie, on montre que, sous certaines hypothèses, le flot géodésique de la surface converge localement uniformément vers le flot de billard. De plus, si le billard est dispersif, les propriétés chaotiques du billard remontent au flot géodésique : on montre qu'il est alors Anosov. En appliquant ce résultat à la théorie des systèmes articulés, on obtient un nouvel exemple de systèmes articulé Anosov, comportant cinq tiges.Dans la troisième partie, on s'intéresse aux variétés munies de connexions localement métriques, c'est-à-dire de connexions qui sont localement des connexions de Levi-Civita de métriques riemanniennes ; on donne dans ce cadre un analogue du théorème de décomposition de De Rham, qui s'applique habituellement aux variétés riemanniennes. Dans le cas où une telle connexion préserve une structure conforme, on montre que cette décomposition comporte au plus deux facteurs ; de plus, lorsqu'il y a exactement deux facteurs, l'un des deux est l'espace euclidien R^q. La démonstration des résultats de cette partie passe par l'étude des feuilletages munis d'une structure de similitude transverse. Sur ces feuilletages, on montre un résultat de rigidité qui peut être vu indépendamment des autres: ils sont soit transversalement plats, soit transversalement riemanniensThis thesis is divided into three parts. In the first part, we study linkages (mechanisms made of rigid rods) whose ambiant space is no longer the plane, but various Riemannian manifolds. We study the question of the universality of linkages: this notion corresponds to the idea that every curve would be traced out by a vertex of some linkage, and that any differentiable manifold would be the configuration space of some linkage. We extend universality theorems to the Minkowski plane, the hyperbolic plane, and finally the sphere.Any surface in R^3 can be flattened with respect to the z-axis, and the flattened surface gets close to a billiard table in R^2. In the second part, we show that, under some hypotheses, the geodesic flow of the surface converges locally uniformly to the billiard flow. Moreover, if the billiard is dispersing, the chaotic properties of the billiard also apply to the geodesic flow: we show that it is Anosov in this case. By applying this result to the theory of linkages, we obtain a new example of Anosov linkage, made of five rods.In the third part, we first consider manifolds with locally metric connections, that is, connections which are locally Levi-Civita connections of Riemannian metrics; we give in this framework an analog of De Rham's decomposition theorem, which usually applies to Riemannian manifolds. In the case such a connection also preserves a conformal structure, we show that this decomposition has at most two factors; moreover, when there are exactly two factors, one of them is the Euclidean space R^q. The proofs of the results of this part use foliations with transverse similarity structures. On these foliations, we give a rigidity theorem of independant interest: they are either transversally flat, or transversally Riemannian
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Briquet, Rafael. "Folheações infinitesimalmente polares." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/45/45131/tde-05052011-115816/.
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O objetivo central desta dissertação é apresentar as folheações infinitesimalmente polares, fornecendo uma demonstração para o teorema que as caracteriza. Seguimos a abordagem original encontrada em Lytchak e Thorbergsson [25], de 2010. Diretamente da definição e do teorema principal obtem-se dois exemplos: folheações polares e folheações riemannianas singulares de codimensão 1 ou 2. Dedicamos especial atenção a um terceiro exemplo: folheações sem pontos horizontalmente conjugados. A demonstração deste resultado utiliza resultados obtidos anteriormente pelos mesmos autores em 2007, Lytchak e Thorbergsson [24]. Abordamos também, brevemente, as implicações do teorema caracterizador (que é um resultado local) sobre o quociente global de uma folheação infinitesimalmente polar. Variedades com folheações infinitesimalmente polares podem ser encaradas como um objeto que apresenta aspectos clássicos do teorema do toro maximal para grupos de Lie compactos, em um contexto mais amplo.The present work aims at introducing infinitesimally polar foliations -- as defined by Lytchak and Thorbergsson [25] -- providing a proof for the classification theorem. Polar foliations and low codimension singular Riemannian foliations are two immediate examples. A third example is given by foliations without horizontally conjugate points. The proof of this assertion relies on previous results established by the same authors in Lytchak and Thorbergsson [24]. The classification theorem for infinitesimally polar foliations is a local result; we also derive from it some global consequences on the quotient space of such foliations. Infinitesimally polar foliations may be regarded as a generalised setting where one can find characteristic features from the maximal torus theorem for compact Lie groups.
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Ferfache, Anouar Abdeldjaoued. "Les M-estimateurs semiparamétriques et leurs applications pour les problèmes de ruptures." Thesis, Compiègne, 2021. http://www.theses.fr/2021COMP2643.
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Dans cette thèse, nous nous intéressons principalement aux modèles semiparamétriques qui ont reçu beaucoup d’intérêt par leur excellente utilité scientifique et leur complexité théorique intrigante. Dans la première partie, nous considérons le problème de l’estimation d’un paramètre dans un espace θ de Banach, en maximisant une fonction critère qui dépend d’un paramètre de nuisance inconnu h, éventuellement de dimension infinie. Nous montrons que le bootstrap m out of n, dans ce cadre général, est consistant sous des conditions similaires à celles requises pour la convergence faible des M-estimateurs non-réguliers. Dans ce cadre délicat, des techniques avancées seront nécessaires pour faire face aux estimateurs du paramètre de nuisance à l’intérieur des fonctions critères non régulières. Nous étudions ensuite le bootstrap échangeable pour les Z-estimateurs. L’ingrédient principal est l’utilisation originale d’une identité différentielle qui s’applique lorsque la fonction critère aléatoire est linéaire en termes de mesure empirique. Un grand nombre de schémas de rééchantillonnage bootstrap apparaissent comme des cas particuliers de notre étude. Des exemples d’applications de la littérature sont présentes pour illustrer la généralité et l’utilité de nos résultats. La deuxième partie est consacrée aux modèles statistiques semiparamétriques de ruptures multiples. L’objectif principal de cette partie est d’étudier les propriétés asymptotiques des M-estimateurs semiparamétriques avec des fonctions critères non lisses des paramètres d’un modèle de rupture multiples pour une classe générale de modèles dans lesquels la forme de la distribution peut changer de segment en segment et dans lesquels, éventuellement, il y a des paramètres communs à tous les segments. La consistance des M-estimateurs semi-paramétriques des points de rupture est établie et la vitesse de convergence est déterminée. La normalité asymptotique des M-estimateurs semiparamétriques des paramètres est établie sous des conditions générales. Nous étendons enfin notre étude au cadre des données censurées. Nous étudions les performances de nos méthodologies pour des petits échantillons à travers des études de simulationsIn this dissertation we are concerned with semiparametric models. These models have success and impact in mathematical statistics due to their excellent scientific utility and intriguing theoretical complexity. In the first part of the thesis, we consider the problem of the estimation of a parameter θ, in Banach spaces, maximizing some criterion function which depends on an unknown nuisance parameter h, possibly infinite-dimensional. We show that the m out of n bootstrap, in a general setting, is weakly consistent under conditions similar to those required for weak convergence of the non smooth M-estimators. In this framework, delicate mathematical derivations will be required to cope with estimators of the nuisance parameters inside non-smooth criterion functions. We then investigate an exchangeable weighted bootstrap for function-valued estimators defined as a zero point of a function-valued random criterion function. The main ingredient is the use of a differential identity that applies when the random criterion function is linear in terms of the empirical measure. A large number of bootstrap resampling schemes emerge as special cases of our settings. Examples of applications from the literature are given to illustrate the generality and the usefulness of our results. The second part of the thesis is devoted to the statistical models with multiple change-points. The main purpose of this part is to investigate the asymptotic properties of semiparametric M-estimators with non-smooth criterion functions of the parameters of multiple change-points model for a general class of models in which the form of the distribution can change from segment to segment and in which, possibly, there are parameters that are common to all segments. Consistency of the semiparametric M-estimators of the change-points is established and the rate of convergence is determined. The asymptotic normality of the semiparametric M-estimators of the parameters of the within-segment distributions is established under quite general conditions. We finally extend our study to the censored data framework. We investigate the performance of our methodologies for small samples through simulation studies
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Leite, Natacha Violante Gomes. "Thermal history of the universe with dark energy component induced by conformal fluctuations of the metric." Master's thesis, 2013. http://hdl.handle.net/10316/36263.
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Haláček, Jakub. "Struktura černoděrových prostoročasů." Master's thesis, 2011. http://www.nusl.cz/ntk/nusl-303924.
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Holubová, Markéta. "Změna třídního klimatu po odchodu žáků na osmiletá gymnázia." Doctoral thesis, 2018. http://www.nusl.cz/ntk/nusl-379250.
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The aim of the dissertation is to compare the psychosocial climate of the classes between the 5th and 6th grades of Czech elementary school. In the train of pupils' leaving into the high- tracked schools there are significant organizational changes in the classes of the 6th grade. This theme includes the phenomenon of the early tracking, when some pupils can leave the mainstream of education (elementary school) and start attending the high-tracked schools (multi-year gymnasium). The aim of our study is to contribute to the research, that with the departure of students into high-tracked schools the psychosocial climate in the classes of the 6th grade unequivocally exacerbates. We are also interested in which specific students are accepted into high-tracked schools, and whether they are effective classroom leaders and socio- metric stars. In our study, we also find out the classroom positions of students who are continuously educated in the 5th and 6th grades of the elementary schools and their classmates, who have come as new students into the classes of the 6th grade. In the theoretical section we introduce the foreign and domestic researches which were conducted on the association between tracking and classroom climate. The empirical part inquiries into a detailed analysis of quantitative research...